Sample records for a-synuclein affects dopamine

  1. Dopamine induces soluble α-synuclein oligomers and nigrostriatal degeneration

    PubMed Central

    Mor, Danielle E.; Tsika, Elpida; Mazzulli, Joseph R.; Gould, Neal S.; Kim, Hanna; Daniels, Malcolm J.; Doshi, Shachee; Gupta, Preetika; Grossman, Jennifer L.; Tan, Victor X.; Kalb, Robert G.; Caldwell, Kim A.; Caldwell, Guy A.; Wolfe, John H.; Ischiropoulos, Harry

    2018-01-01

    Parkinson’s disease is defined by the loss of dopaminergic neurons in the substantia nigra and formation of Lewy body inclusions containing aggregated α-synuclein. Efforts to explain dopamine neuron vulnerability are hindered by the lack of dopaminergic cell death in α-synuclein transgenic mice. To address this, we manipulated dopamine levels in addition to α-synuclein expression. Nigra-targeted expression of mutant tyrosine hydroxylase with enhanced catalytic activity increased dopamine without damaging neurons in non-transgenic mice. In contrast, raising dopamine in mice expressing human A53T mutant α-synuclein induced progressive nigrostriatal degeneration and reduced locomotion. Dopamine elevation in A53T mice increased levels of potentially toxic α-synuclein oligomers, resulting in conformationally and functionally modified species. Moreover, in genetically tractable C. elegans models expression of α-synuclein mutated at the site of interaction with dopamine prevented dopamine-induced toxicity. The data suggest a unique mechanism linking two cardinal features of Parkinson’s disease, dopaminergic cell death and α-synuclein aggregation. PMID:28920936

  2. Dopamine induces soluble α-synuclein oligomers and nigrostriatal degeneration.

    PubMed

    Mor, Danielle E; Tsika, Elpida; Mazzulli, Joseph R; Gould, Neal S; Kim, Hanna; Daniels, Malcolm J; Doshi, Shachee; Gupta, Preetika; Grossman, Jennifer L; Tan, Victor X; Kalb, Robert G; Caldwell, Kim A; Caldwell, Guy A; Wolfe, John H; Ischiropoulos, Harry

    2017-11-01

    Parkinson's disease (PD) is defined by the loss of dopaminergic neurons in the substantia nigra and the formation of Lewy body inclusions containing aggregated α-synuclein. Efforts to explain dopamine neuron vulnerability are hindered by the lack of dopaminergic cell death in α-synuclein transgenic mice. To address this, we manipulated both dopamine levels and α-synuclein expression. Nigrally targeted expression of mutant tyrosine hydroxylase with enhanced catalytic activity increased dopamine levels without damaging neurons in non-transgenic mice. In contrast, raising dopamine levels in mice expressing human A53T mutant α-synuclein induced progressive nigrostriatal degeneration and reduced locomotion. Dopamine elevation in A53T mice increased levels of potentially toxic α-synuclein oligomers, resulting in conformationally and functionally modified species. Moreover, in genetically tractable Caenorhabditis elegans models, expression of α-synuclein mutated at the site of interaction with dopamine prevented dopamine-induced toxicity. These data suggest that a unique mechanism links two cardinal features of PD: dopaminergic cell death and α-synuclein aggregation.

  3. Atomic force microscopy based nanoassay: a new method to study α-Synuclein-dopamine bioaffinity interactions

    NASA Astrophysics Data System (ADS)

    Corvaglia, Stefania; Sanavio, Barbara; Sorce, Barbara; Bosco, Alessandro; Sabella, Stefania; Pompa, Pierpaolo; Scoles, Giacinto; Casalis, Loredana

    2015-03-01

    Intrinsically Disordered Proteins (IDPs) are characterized by the lack of well-defined 3-D structure and show high conformational plasticity. For this reason, they are a strong challenge for the traditional characterization of structure, supramolecular assembly and biorecognition phenomena. We show here how the fine tuning of protein orientation on a surface turns useful in the reliable testing of biorecognition interactions of IDPs, in particular α-Synuclein. We exploited atomic force microscopy (AFM) for the selective, nanoscale confinement of α-Synuclein on gold to study the early stages of α-Synuclein aggregation and the effect of small molecules, like dopamine, on the aggregation process. Capitalizing on the high sensitivity of AFM topographic height measurements we determined, for the first time in the literature, the dissociation constant of dopamine- α-Synuclein adducts.

  4. Atomic force microscopy based nanoassay: a new method to study α-Synuclein-dopamine bioaffinity interactions

    NASA Astrophysics Data System (ADS)

    Corvaglia, Stefania; Sanavio, Barbara; Hong Enriquez, Rolando P.; Sorce, Barbara; Bosco, Alessandro; Scaini, Denis; Sabella, Stefania; Pompa, Pier Paolo; Scoles, Giacinto; Casalis, Loredana

    2014-06-01

    Intrinsically Disordered Proteins (IDPs) are characterized by the lack of well-defined 3-D structure and show high conformational plasticity. For this reason, they are a strong challenge for the traditional characterization of structure, supramolecular assembly and biorecognition phenomena. We show here how the fine tuning of protein orientation on a surface turns useful in the reliable testing of biorecognition interactions of IDPs, in particular α-Synuclein. We exploited atomic force microscopy (AFM) for the selective, nanoscale confinement of α-Synuclein on gold to study the early stages of α-Synuclein aggregation and the effect of small molecules, like dopamine, on the aggregation process. Capitalizing on the high sensitivity of AFM topographic height measurements we determined, for the first time in the literature, the dissociation constant of dopamine-α-Synuclein adducts.

  5. Dopamine and α-synuclein dysfunction in Smad3 null mice

    PubMed Central

    2011-01-01

    Background Parkinson's disease (PD) is characterized by dopaminergic neurodegeneration in the substantia nigra (SN). Transforming growth factor-β1 (TGF-β1) levels increase in patients with PD, although the effects of this increment remain unclear. We have examined the mesostriatal system in adult mice deficient in Smad3, a molecule involved in the intracellular TGF-β1 signalling cascade. Results Striatal monoamine oxidase (MAO)-mediated dopamine (DA) catabolism to 3,4-dihydroxyphenylacetic acid (DOPAC) is strongly increased, promoting oxidative stress that is reflected by an increase in glutathione levels. Fewer astrocytes are detected in the ventral midbrain (VM) and striatal matrix, suggesting decreased trophic support to dopaminergic neurons. The SN of these mice has dopaminergic neuronal degeneration in its rostral portion, and the pro-survival Erk1/2 signalling is diminished in nigra dopaminergic neurons, not associated with alterations to p-JNK or p-p38. Furthermore, inclusions of α-synuclein are evident in selected brain areas, both in the perikaryon (SN and paralemniscal nucleus) or neurites (motor and cingulate cortices, striatum and spinal cord). Interestingly, these α-synuclein deposits are detected with ubiquitin and PS129-α-synuclein in a core/halo cellular distribution, which resemble those observed in human Lewy bodies (LB). Conclusions Smad3 deficiency promotes strong catabolism of DA in the striatum (ST), decrease trophic and astrocytic support to dopaminergic neurons and may induce α-synuclein aggregation, which may be related to early parkinsonism. These data underline a role for Smad3 in α-synuclein and DA homeostasis, and suggest that modulatory molecules of this signalling pathway should be evaluated as possible neuroprotective agents. PMID:21995845

  6. Lrrk2 and alpha-synuclein are co-regulated in rodent striatum.

    PubMed

    Westerlund, Marie; Ran, Caroline; Borgkvist, Anders; Sterky, Fredrik H; Lindqvist, Eva; Lundströmer, Karin; Pernold, Karin; Brené, Stefan; Kallunki, Pekka; Fisone, Gilberto; Olson, Lars; Galter, Dagmar

    2008-12-01

    LRRK2, alpha-synuclein, UCH-L1 and DJ-1 are implicated in the etiology of Parkinson's disease. We show for the first time that increase in striatal alpha-synuclein levels induce increased Lrrk2 mRNA levels while Dj-1 and Uch-L1 are unchanged. We also demonstrate that a mouse strain lacking the dopamine signaling molecule DARPP-32 has significantly reduced levels of both Lrrk2 and alpha-synuclein, while mice carrying a disabling mutation of the DARPP-32 phosphorylation site T34A or lack alpha-synuclein do not show any changes. To test if striatal dopamine depletion influences Lrrk2 or alpha-synuclein expression, we used the neurotoxin 6-hydroxydopamine in rats and MitoPark mice in which there is progressive degeneration of dopamine neurons. Because striatal Lrrk2 and alpha-synuclein levels were not changed by dopamine depletion, we conclude that Lrrk2 and alpha-synuclein mRNA levels are possibly co-regulated, but they are not influenced by striatal dopamine levels.

  7. α-synuclein and synapsin III cooperatively regulate synaptic function in dopamine neurons.

    PubMed

    Zaltieri, Michela; Grigoletto, Jessica; Longhena, Francesca; Navarria, Laura; Favero, Gaia; Castrezzati, Stefania; Colivicchi, Maria Alessandra; Della Corte, Laura; Rezzani, Rita; Pizzi, Marina; Benfenati, Fabio; Spillantini, Maria Grazia; Missale, Cristina; Spano, PierFranco; Bellucci, Arianna

    2015-07-01

    The main neuropathological features of Parkinson's disease are dopaminergic nigrostriatal neuron degeneration, and intraneuronal and intraneuritic proteinaceous inclusions named Lewy bodies and Lewy neurites, respectively, which mainly contain α-synuclein (α-syn, also known as SNCA). The neuronal phosphoprotein synapsin III (also known as SYN3), is a pivotal regulator of dopamine neuron synaptic function. Here, we show that α-syn interacts with and modulates synapsin III. The absence of α-syn causes a selective increase and redistribution of synapsin III, and changes the organization of synaptic vesicle pools in dopamine neurons. In α-syn-null mice, the alterations of synapsin III induce an increased locomotor response to the stimulation of synapsin-dependent dopamine overflow, despite this, these mice show decreased basal and depolarization-dependent striatal dopamine release. Of note, synapsin III seems to be involved in α-syn aggregation, which also coaxes its increase and redistribution. Furthermore, synapsin III accumulates in the caudate and putamen of individuals with Parkinson's disease. These findings support a reciprocal modulatory interaction of α-syn and synapsin III in the regulation of dopamine neuron synaptic function. © 2015. Published by The Company of Biologists Ltd.

  8. Reynosin protects against neuronal toxicity in dopamine-induced SH-SY5Y cells and 6-hydroxydopamine-lesioned rats as models of Parkinson's disease: Reciprocal up-regulation of E6-AP and down-regulation of α-synuclein.

    PubMed

    Ham, Ahrom; Kim, Dong-Woo; Kim, Kyeong Ho; Lee, Sung-Jin; Oh, Ki-Bong; Shin, Jongheon; Mar, Woongchon

    2013-08-02

    Aggregation of α-synuclein (ASYN) is considered a major determinant of neuronal loss in Parkinson's disease (PD). E6-associated protein (E6-AP), an E3 ubiquitin protein ligase, has been known to promote the degradation of α-synuclein. The aim of this study was to assess the effects of the sesquiterpene lactone reynosin on dopamine (DA)-induced neuronal toxicity and regulation of E6-associated protein and α-synuclein proteins in both in vitro and in vivo models of Parkinson's disease. Usi"ng flow cytometry and western blot analysis, we determined that reynosin significantly protected both against cell death from dopamine-induced toxicity in human neuroblastoma SH-SY5Y cells and against the loss of tyrosine hydroxylase (TH)-positive cells in 6-hydroxydopamine (6-OHDA)-lesioned rats (a rodent Parkinson's disease model system). In addition, reynosin made up-regulation of E6-associated protein expression and down-regulation of the over-expression of α-synuclein protein in both dopamine-treated SH-SY5Y cells and 6-hydroxydopamine-lesioned rats. These results suggest that the protective effect of reynosin against dopamine-induced neuronal cell death may be due to the reciprocal up-regulation of E6-associated protein and down-regulation of α-synuclein protein expression. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Role of alpha-synuclein in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonism in mice.

    PubMed

    Schlüter, O M; Fornai, F; Alessandrí, M G; Takamori, S; Geppert, M; Jahn, R; Südhof, T C

    2003-01-01

    In humans, mutations in the alpha-synuclein gene or exposure to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produce Parkinson's disease with loss of dopaminergic neurons and depletion of nigrostriatal dopamine. alpha-Synuclein is a vertebrate-specific component of presynaptic nerve terminals that may function in modulating synaptic transmission. To test whether MPTP toxicity involves alpha-synuclein, we generated alpha-synuclein-deficient mice by homologous recombination, and analyzed the effect of deleting alpha-synuclein on MPTP toxicity using these knockout mice. In addition, we examined commercially available mice that contain a spontaneous loss of the alpha-synuclein gene. As described previously, deletion of alpha-synuclein had no significant effects on brain structure or composition. In particular, the levels of synaptic proteins were not altered, and the concentrations of dopamine, dopamine metabolites, and dopaminergic proteins were unchanged. Upon acute MPTP challenge, alpha-synuclein knockout mice were partly protected from chronic depletion of nigrostriatal dopamine when compared with littermates of the same genetic background, whereas mice carrying the spontaneous deletion of the alpha-synuclein gene exhibited no protection. Furthermore, alpha-synuclein knockout mice but not the mice with the alpha-synuclein gene deletion were slightly more sensitive to methamphetamine than littermate control mice. These results demonstrate that alpha-synuclein is not obligatorily coupled to MPTP sensitivity, but can influence MPTP toxicity on some genetic backgrounds, and illustrate the need for extensive controls in studies aimed at describing the effects of mouse knockouts on MPTP sensitivity.

  10. The Contribution of α-Synuclein Spreading to Parkinson's Disease Synaptopathy

    PubMed Central

    Faustini, Gaia; Missale, Cristina; Pizzi, Marina; Spano, PierFranco

    2017-01-01

    Synaptopathies are diseases with synapse defects as shared pathogenic features, encompassing neurodegenerative disorders such as Parkinson's disease (PD). In sporadic PD, the most common age-related neurodegenerative movement disorder, nigrostriatal dopaminergic deficits are responsible for the onset of motor symptoms that have been related to α-synuclein deposition at synaptic sites. Indeed, α-synuclein accumulation can impair synaptic dopamine release and induces the death of nigrostriatal neurons. While in physiological conditions the protein can interact with and modulate synaptic vesicle proteins and membranes, numerous experimental evidences have confirmed that its pathological aggregation can compromise correct neuronal functioning. In addition, recent findings indicate that α-synuclein pathology spreads into the brain and can affect the peripheral autonomic and somatic nervous system. Indeed, monomeric, oligomeric, and fibrillary α-synuclein can move from cell to cell and can trigger the aggregation of the endogenous protein in recipient neurons. This novel “prion-like” behavior could further contribute to synaptic failure in PD and other synucleinopathies. This review describes the major findings supporting the occurrence of α-synuclein pathology propagation in PD and discusses how this phenomenon could induce or contribute to synaptic injury and degeneration. PMID:28133550

  11. AAV1/2-induced overexpression of A53T-α-synuclein in the substantia nigra results in degeneration of the nigrostriatal system with Lewy-like pathology and motor impairment: a new mouse model for Parkinson's disease.

    PubMed

    Ip, Chi Wang; Klaus, Laura-Christin; Karikari, Akua A; Visanji, Naomi P; Brotchie, Jonathan M; Lang, Anthony E; Volkmann, Jens; Koprich, James B

    2017-02-01

    α-Synuclein is a protein implicated in the etiopathogenesis of Parkinson's disease (PD). AAV1/2-driven overexpression of human mutated A53T-α-synuclein in rat and monkey substantia nigra (SN) induces degeneration of nigral dopaminergic neurons and decreases striatal dopamine and tyrosine hydroxylase (TH). Given certain advantages of the mouse, especially it being amendable to genetic manipulation, translating the AAV1/2-A53T α-synuclein model to mice would be of significant value. AAV1/2-A53T α-synuclein or AAV1/2 empty vector (EV) at a concentration of 5.16 x 10 12 gp/ml were unilaterally injected into the right SN of male adult C57BL/6 mice. Post-mortem examinations included immunohistochemistry to analyze nigral α-synuclein, Ser129 phosphorylated α-synuclein and TH expression, striatal dopamine transporter (DAT) levels by autoradiography and dopamine levels by high performance liquid chromatography. At 10 weeks, in AAV1/2-A53T α-synuclein mice there was a 33% reduction in TH+ dopaminergic nigral neurons (P < 0.001), 29% deficit in striatal DAT binding (P < 0.05), 38% and 33% reductions in dopamine (P < 0.001) and DOPAC (P < 0.01) levels and a 60% increase in dopamine turnover (homovanilic acid/dopamine ratio; P < 0.001). Immunofluorescence showed that the AAV1/2-A53T α-synuclein injected mice had widespread nigral and striatal expression of vector-delivered A53T-α-synuclein. Concurrent staining with human PD SN samples using gold standard histological methodology for Lewy pathology detection by proteinase K digestion and application of specific antibody raised against human Lewy body α-synuclein (LB509) and Ser129 phosphorylated α-synuclein (81A) revealed insoluble α-synuclein aggregates in AAV1/2-A53T α-synuclein mice resembling Lewy-like neurites and bodies. In the cylinder test, we observed significant paw use asymmetry in the AAV1/2-A53T α-synuclein group when compared to EV controls at 5 and 9 weeks post injection (P

  12. Phthalocyanine tetrasulfonates affect the amyloid formation and cytotoxicity of alpha-synuclein.

    PubMed

    Lee, Eui-Nam; Cho, Hyun-Ju; Lee, Choong-Hwan; Lee, Daekyun; Chung, Kwang Chul; Paik, Seung R

    2004-03-30

    Alpha-synuclein is a pathological component of Parkinson's disease by constituting the filamentous component of Lewy bodies. Phthalocyanine (Pc) effects on the amyloidosis of alpha-synuclein have been examined. The copper complex of phthalocyanine tetrasulfonate (PcTS-Cu(2+)) caused the self-oligomerization of alpha-synuclein while Pc-Cu(2+) did not affect the protein, indicating that introduction of the sulfonate groups was critical for the selective protein interaction. The PcTS-Cu(2+) interaction with alpha-synuclein has occurred predominantly at the N-terminal region of the protein with a K(d) of 0.83 microM apart from the hydrophobic NAC (non-Abeta component of Alzheimer's disease amyloid) segment. Phthalocyanine tetrasulfonate (PcTS) lacking the intercalated copper ion also showed a considerable affinity toward alpha-synuclein with a K(d) of 3.12 microM, and its binding site, on the other hand, was located at the acidic C-terminus. These mutually exclusive interactions between PcTS and PcTS-Cu(2+) toward alpha-synuclein resulted in distinctive features on the kinetics of protein aggregation, morphologies of the final aggregates, and their in vitro cytotoxicities. The PcTS actually suppressed the fibrous amyloid formation of alpha-synuclein, but it produced the chopped-wood-looking protein aggregates. The aggregates showed rather low toxicity (9.5%) on human neuroblastoma cells (SH-SY5Y). In fact, the PcTS was shown to effectively rescue the cell death of alpha-synuclein overexpressing cells caused by the lactacystin treatment as a proteasome inhibitor. The anti-aggregative and anti-amyloidogenic properties of PcTS were also demonstrated with alcohol dehydrogenase, glutathione S-transferase, and amyloid beta/A4 protein under their aggregative conditions. The PcTS-Cu(2+), on the other hand, promoted the protein aggregation of alpha-synuclein, which gave rise to the fibrillar protein aggregates whose cytotoxicity became significant to 35.8%. Taken together, the

  13. DNA damage preceding dopamine neuron degeneration in A53T human α-synuclein transgenic mice.

    PubMed

    Wang, Degui; Yu, Tianyu; Liu, Yongqiang; Yan, Jun; Guo, Yingli; Jing, Yuhong; Yang, Xuguang; Song, Yanfeng; Tian, Yingxia

    2016-12-02

    Defective DNA repair has been linked with age-associated neurodegenerative disorders. Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by genetic and environmental factors. Whether damages to nuclear DNA contribute to neurodegeneration of PD still remain obscure. in this study we aim to explore whether nuclear DNA damage induce dopamine neuron degeneration in A53T human α-Synuclein over expressed mouse model. We investigated the effects of X-ray irradiation on A53T-α-Syn MEFs and A53T-α-Syn transgene mice. Our results indicate that A53T-α-Syn MEFs show a prolonged DNA damage repair process and senescense phenotype. DNA damage preceded onset of motor phenotype in A53T-α-Syn transgenic mice and decrease the number of nigrostriatal dopaminergic neurons. Neurons of A53T-α-Syn transgenic mice are more fragile to DNA damages. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Transcriptional profiling of striatal neurons in response to single or concurrent activation of dopamine D2, adenosine A(2A) and metabotropic glutamate type 5 receptors: focus on beta-synuclein expression.

    PubMed

    Canela, Laia; Selga, Elisabet; García-Martínez, Juan Manuel; Amaral, Olavo B; Fernández-Dueñas, Víctor; Alberch, Jordi; Canela, Enric I; Franco, Rafael; Noé, Véronique; Lluís, Carme; Ciudad, Carlos J; Ciruela, Francisco

    2012-10-25

    G protein-coupled receptor oligomerization is a concept which is changing the understanding of classical pharmacology. Both, oligomerization and functional interaction between adenosine A(2A,) dopamine D(2) and metabotropic glutamate type 5 receptors have been demonstrated in the striatum. However, the transcriptional consequences of receptors co-activation are still unexplored. We aim here to determine the changes in gene expression of striatal primary cultured neurons upon isolated or simultaneous receptor activation. Interestingly, we found that 95 genes of the total analyzed (15,866 transcripts and variants) changed their expression in response to simultaneous stimulation of all three receptors. Among these genes, we focused on the β-synuclein (β-Syn) gene (SCNB). Quantitative PCR verified the magnitude and direction of change in expression of SCNB. Since β-Syn belongs to the homologous synuclein family and may be considered a natural regulator of α-synuclein (α-Syn), it has been proposed that β-Syn might act protectively against α-Syn neuropathology. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Plasma α-synuclein and cognitive impairment in the Parkinson's Associated Risk Syndrome: A pilot study.

    PubMed

    Wang, Hua; Atik, Anzari; Stewart, Tessandra; Ginghina, Carmen; Aro, Patrick; Kerr, Kathleen F; Seibyl, John; Jennings, Danna; Jensen, Poul Henning; Marek, Kenneth; Shi, Min; Zhang, Jing

    2018-04-27

    Plasma total and nervous system derived exosomal (NDE) α-synuclein have been determined as potential biomarkers of Parkinson's disease (PD). To explore the utility of plasma α-synuclein in the prodromal phase of PD, plasma total and NDE α-synuclein were evaluated in baseline and 2-year follow-up samples from 256 individuals recruited as part of the Parkinson's Associated Risk Syndrome (PARS) study. The results demonstrated that baseline and longitudinal increases in total α-synuclein predicted progression of cognitive decline in hyposmic individuals with dopamine transporter (DAT) binding reduction. On the other hand, a longitudinal decrease in NDE α-synuclein predicted worsening cognitive scores in hyposmic individuals with DAT binding reduction. Finally, in individuals with faster DAT progression, decreasing NDE/total α-synuclein ratio was associated with a larger reduction in DAT from baseline to follow-up. These results suggest that, though underlying mechanisms remain to be defined, alterations in plasma total and NDE α-synuclein concentrations are likely associated with PD progression, especially in the aspect of cognitive impairment, at early stages of the disease. Copyright © 2018. Published by Elsevier Inc.

  16. Ca2+ is a key factor in α-synuclein-induced neurotoxicity

    PubMed Central

    Angelova, Plamena R.; Ludtmann, Marthe H. R.; Horrocks, Mathew H.; Negoda, Alexander; Cremades, Nunilo; Klenerman, David; Dobson, Christopher M.; Wood, Nicholas W.; Pavlov, Evgeny V.; Gandhi, Sonia

    2016-01-01

    ABSTRACT Aggregation of α-synuclein leads to the formation of oligomeric intermediates that can interact with membranes to form pores. However, it is unknown how this leads to cell toxicity in Parkinson's disease. We investigated the species-specific effects of α-synuclein on Ca2+ signalling in primary neurons and astrocytes using live neuronal imaging and electrophysiology on artificial membranes. We demonstrate that α-synuclein induces an increase in basal intracellular Ca2+ in its unfolded monomeric state as well as in its oligomeric state. Electrophysiology of artificial membranes demonstrated that α-synuclein monomers induce irregular ionic currents, whereas α-synuclein oligomers induce rare discrete channel formation events. Despite the ability of monomeric α-synuclein to affect Ca2+ signalling, it is only the oligomeric form of α-synuclein that induces cell death. Oligomer-induced cell death was abolished by the exclusion of extracellular Ca2+, which prevented the α-synuclein-induced Ca2+ dysregulation. The findings of this study confirm that α-synuclein interacts with membranes to affect Ca2+ signalling in a structure-specific manner and the oligomeric β-sheet-rich α-synuclein species ultimately leads to Ca2+ dysregulation and Ca2+-dependent cell death. PMID:26989132

  17. Alpha-synuclein: relating metals to structure, function and inhibition.

    PubMed

    McDowall, J S; Brown, D R

    2016-04-01

    Alpha-synuclein has long been studied due to its involvement in the progression of Parkinson's disease (PD), a common neurodegenerative disorder, although a consensus on the exact function of this protein is elusive. This protein shows remarkable structural plasticity and this property is important for both correct cellular function and pathological progression of PD. Formation of intracellular oligomeric species within the substantia nigra correlates with disease progression and it has been proposed that formation of a partially folded intermediate is key to the initiation of the fibrillisation process. Many factors can influence changes in the structure of alpha-synuclein such as disease mutations and interaction with metals and neurotransmitters. High concentrations of both dopamine and metals are present in the substantia nigra making this an ideal location for both the structural alteration of alpha-synuclein and the production of toxic oxygen species. The recent proposal that alpha-synuclein is a ferrireductase is important as it can possibly catalyse the formation of such reactive species and as a result exacerbate neurodegeneration.

  18. Geraniol attenuates α-synuclein expression and neuromuscular impairment through increase dopamine content in MPTP intoxicated mice by dose dependent manner.

    PubMed

    Rekha, Karamkolly R; Selvakumar, Govindasamy P; Santha, Karunanithi; Inmozhi Sivakamasundari, Ramu

    2013-11-01

    Parkinson's disease (PD) is characterized by progressive loss of dopamine (DA) neurons in the nigrostriatal system and by the presence of Lewy bodies (LB), proteinaceous inclusions mainly composed of filamentous α-synuclein (α-Syn) aggregates. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was adopted to generate PD models in C57BL/6 mice. In the present study, we investigated the effect of geraniol (GE) against α-Syn aggregation on MPTP induced mouse model of PD in dose dependant manner. When pretreatment of GE improved neuromuscular impairment, TH expressions and decreases α-Syn expressions in MPTP intoxicated PD mice by dose dependent manner. In addition, we confirmed that sub-chronic administration of MPTP in mice leads to permanent neuromuscular deficits and depletion of dopamine and its metabolites. Our results suggest that GE is beneficial for the treatment of PD associated with neuromuscular disability and LB aggregation. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  19. β-Synuclein suppresses both the initiation and amplification steps of α-synuclein aggregation via competitive binding to surfaces

    NASA Astrophysics Data System (ADS)

    Brown, James W. P.; Buell, Alexander K.; Michaels, Thomas C. T.; Meisl, Georg; Carozza, Jacqueline; Flagmeier, Patrick; Vendruscolo, Michele; Knowles, Tuomas P. J.; Dobson, Christopher M.; Galvagnion, Céline

    2016-11-01

    α-Synuclein is an intrinsically disordered protein that is associated with the pathogenesis of Parkinson’s disease through the processes involved in the formation of amyloid fibrils. α and β-synuclein are homologous proteins found at comparable levels in presynaptic terminals but β-synuclein has a greatly reduced propensity to aggregate and indeed has been found to inhibit α-synuclein aggregation. In this paper, we describe how sequence differences between α- and β-synuclein affect individual microscopic processes in amyloid formation. In particular, we show that β-synuclein strongly suppresses both lipid-induced aggregation and secondary nucleation of α-synuclein by competing for binding sites at the surfaces of lipid vesicles and fibrils, respectively. These results suggest that β-synuclein can act as a natural inhibitor of α-synuclein aggregation by reducing both the initiation of its self-assembly and the proliferation of its aggregates.

  20. Redistribution of DAT/α-Synuclein Complexes Visualized by “In Situ” Proximity Ligation Assay in Transgenic Mice Modelling Early Parkinson's Disease

    PubMed Central

    Bellucci, Arianna; Navarria, Laura; Falarti, Elisa; Zaltieri, Michela; Bono, Federica; Collo, Ginetta; Grazia, Maria; Missale, Cristina; Spano, PierFranco

    2011-01-01

    Alpha-synuclein, the major component of Lewy bodies, is thought to play a central role in the onset of synaptic dysfunctions in Parkinson's disease (PD). In particular, α-synuclein may affect dopaminergic neuron function as it interacts with a key protein modulating dopamine (DA) content at the synapse: the DA transporter (DAT). Indeed, recent evidence from our “in vitro” studies showed that α-synuclein aggregation decreases the expression and membrane trafficking of the DAT as the DAT is retained into α-synuclein-immunopositive inclusions. This notwithstanding, “in vivo” studies on PD animal models investigating whether DAT distribution is altered by the pathological overexpression and aggregation of α-synuclein are missing. By using the proximity ligation assay, a technique which allows the “in situ” visualization of protein-protein interactions, we studied the occurrence of alterations in the distribution of DAT/α-synuclein complexes in the SYN120 transgenic mouse model, showing insoluble α-synuclein aggregates into dopaminergic neurons of the nigrostriatal system, reduced striatal DA levels and an altered distribution of synaptic proteins in the striatum. We found that DAT/α-synuclein complexes were markedly redistributed in the striatum and substantia nigra of SYN120 mice. These alterations were accompanied by a significant increase of DAT striatal levels in transgenic animals when compared to wild type littermates. Our data indicate that, in the early pathogenesis of PD, α-synuclein acts as a fine modulator of the dopaminergic synapse by regulating the subcellular distribution of key proteins such as the DAT. PMID:22163275

  1. Induction of the Immunoproteasome Subunit Lmp7 Links Proteostasis and Immunity in α-Synuclein Aggregation Disorders.

    PubMed

    Ugras, Scott; Daniels, Malcolm J; Fazelinia, Hossein; Gould, Neal S; Yocum, Anastasia K; Luk, Kelvin C; Luna, Esteban; Ding, Hua; McKennan, Chris; Seeholzer, Steven; Martinez, Dan; Evans, Perry; Brown, Daniel; Duda, John E; Ischiropoulos, Harry

    2018-05-01

    Accumulation of aggregated α-synuclein into Lewy bodies is thought to contribute to the onset and progression of dopaminergic neuron degeneration in Parkinson's disease (PD) and related disorders. Although protein aggregation is associated with perturbation of proteostasis, how α-synuclein aggregation affects the brain proteome and signaling remains uncertain. In a mouse model of α-synuclein aggregation, 6% of 6215 proteins and 1.6% of 8183 phosphopeptides changed in abundance, indicating conservation of proteostasis and phosphorylation signaling. The proteomic analysis confirmed changes in abundance of proteins that regulate dopamine synthesis and transport, synaptic activity and integrity, and unearthed changes in mRNA binding, processing and protein translation. Phosphorylation signaling changes centered on axonal and synaptic cytoskeletal organization and structural integrity. Proteostatic responses included a significant increase in the levels of Lmp7, a component of the immunoproteasome. Increased Lmp7 levels and activity were also quantified in postmortem human brains with PD and dementia with Lewy bodies. Functionally, the immunoproteasome degrades α-synuclein aggregates and generates potentially antigenic peptides. Expression and activity of the immunoproteasome may represent testable targets to induce adaptive responses that maintain proteome integrity and modulate immune responses in protein aggregation disorders. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  2. [Targeted inactivation of gamma-synuclein gene affects anxiety and exploratory behaviour of mice].

    PubMed

    Kokhan, V S; Bolkunov, A V; Ustiugov, A A; Van'kin, G I; Shelkovnikova, T A; Redkozubova, O M; Strekalova, T V; Bukhman, V L; Ninkina, N N; Bachurin, S O

    2011-01-01

    Gamma(gamma)-synuclein is a member of synuclein family of cytoplasmic and predominantly neuronal proteins found only in vertebrates. Gamma-synuclein is abundant in axons and presynaptic terminals of neurons localized in brain regions involved in emotions, learning and memory. However, the role of gamma-synuclein in these brain functions was not previously assessed. We have demonstrated for the first time that the loss of gamma-synuclein results in a significant increase in the level of orientation response in novel environment and decrease in the level of state anxiety.

  3. DNA damage preceding dopamine neuron degeneration in A53T human α-synuclein transgenic mice

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Degui; Yu, Tianyu; Liu, Yongqiang

    Defective DNA repair has been linked with age-associated neurodegenerative disorders. Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by genetic and environmental factors. Whether damages to nuclear DNA contribute to neurodegeneration of PD still remain obscure. in this study we aim to explore whether nuclear DNA damage induce dopamine neuron degeneration in A53T human α-Synuclein over expressed mouse model. We investigated the effects of X-ray irradiation on A53T-α-Syn MEFs and A53T-α-Syn transgene mice. Our results indicate that A53T-α-Syn MEFs show a prolonged DNA damage repair process and senescense phenotype. DNA damage preceded onset of motor phenotype in A53T-α-Syn transgenicmore » mice and decrease the number of nigrostriatal dopaminergic neurons. Neurons of A53T-α-Syn transgenic mice are more fragile to DNA damages. - Highlights: • This study explore contribution of DNA damage to neurodegeneration in Parkinson's disease mice. • A53T-α-Syn MEF cells show a prolonged DNA damage repair process and senescense phenotype. • DNA damage preceded onset of motor phenotype in A53T-α-Syn transgenic mice. • DNA damage decrease the number of nigrostriatal dopaminergic neurons. • Neurons of A53T-α-Syn transgenic mice are more fragile to DNA damages.« less

  4. Psychostimulants affect dopamine transmission through both dopamine transporter-dependent and independent mechanisms

    PubMed Central

    dela Peña, Ike; Gevorkiana, Ruzanna; Shi, Wei-Xing

    2015-01-01

    The precise mechanisms by which cocaine and amphetamine-like psychostimulants exert their reinforcing effects are not yet fully defined. It is widely believed, however, that these drugs produce their effects by enhancing dopamine neurotransmission in the brain, especially in limbic areas such as the nucleus accumbens, by inducing dopamine transporter-mediated reverse transport and/or blocking dopamine reuptake though the dopamine transporter. Here, we present the evidence that aside from dopamine transporter, non-dopamine transporter-mediated mechanisms also participate in psychostimulant-induced dopamine release and contribute to the behavioral effects of these drugs, such as locomotor activation and reward. Accordingly, psychostimulants could increase norepinephrine release in the prefrontal cortex, the latter then alters the firing pattern of dopamine neurons resulting in changes in action potential-dependent dopamine release. These alterations would further affect the temporal pattern of dopamine release in the nucleus accumbens, thereby modifying information processing in that area. Hence, a synaptic input to a nucleus accumbens neuron may be enhanced or inhibited by dopamine depending on its temporal relationship to dopamine release. Specific temporal patterns of dopamine release may also be required for certain forms of synaptic plasticity in the nucleus accumbens. Together, these effects induced by psychostimulants, mediated through a non-dopamine transporter-mediated mechanism involving norepinephrine and the prefrontal cortex, may also contribute importantly to the reinforcing properties of these drugs. PMID:26209364

  5. Long-term oral kinetin does not protect against α-synuclein-induced neurodegeneration in rodent models of Parkinson's disease.

    PubMed

    Orr, Adam L; Rutaganira, Florentine U; de Roulet, Daniel; Huang, Eric J; Hertz, Nicholas T; Shokat, Kevan M; Nakamura, Ken

    2017-10-01

    Mutations in the mitochondrial kinase PTEN-induced putative kinase 1 (PINK1) cause Parkinson's disease (PD), likely by disrupting PINK1's kinase activity. Although the mechanism(s) underlying how this loss of activity causes degeneration remains unclear, increasing PINK1 activity may therapeutically benefit some forms of PD. However, we must first learn whether restoring PINK1 function prevents degeneration in patients harboring PINK1 mutations, or whether boosting PINK1 function can offer protection in more common causes of PD. To test these hypotheses in preclinical rodent models of PD, we used kinetin triphosphate, a small-molecule that activates both wild-type and mutant forms of PINK1, which affects mitochondrial function and protects neural cells in culture. We chronically fed kinetin, the precursor of kinetin triphosphate, to PINK1-null rats in which PINK1 was reintroduced into their midbrain, and also to rodent models overexpressing α-synuclein. The highest tolerated dose of oral kinetin increased brain levels of kinetin for up to 6 months, without adversely affecting the survival of nigrostriatal dopamine neurons. However, there was no degeneration of midbrain dopamine neurons lacking PINK1, which precluded an assessment of neuroprotection and raised questions about the robustness of the PINK1 KO rat model of PD. In two rodent models of α-synuclein-induced toxicity, boosting PINK1 activity with oral kinetin provided no protective effects. Our results suggest that oral kinetin is unlikely to protect against α-synuclein toxicity, and thus fail to provide evidence that kinetin will protect in sporadic models of PD. Kinetin may protect in cases of PINK1 deficiency, but this possibility requires a more robust PINK1 KO model that can be validated by proof-of-principle genetic correction in adult animals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. VPS35 in Dopamine Neurons Is Required for Endosome-to-Golgi Retrieval of Lamp2a, a Receptor of Chaperone-Mediated Autophagy That Is Critical for α-Synuclein Degradation and Prevention of Pathogenesis of Parkinson's Disease

    PubMed Central

    Tang, Fu-Lei; Erion, Joanna R.; Tian, Yun; Liu, Wei; Yin, Dong-Min; Ye, Jian; Tang, Baisha; Mei, Lin

    2015-01-01

    Vacuolar protein sorting-35 (VPS35) is essential for endosome-to-Golgi retrieval of membrane proteins. Mutations in the VPS35 gene have been identified in patients with autosomal dominant PD. However, it remains poorly understood if and how VPS35 deficiency or mutation contributes to PD pathogenesis. Here we provide evidence that links VPS35 deficiency to PD-like neuropathology. VPS35 was expressed in mouse dopamine (DA) neurons in substantia nigra pars compacta (SNpc) and STR (striatum)—regions that are PD vulnerable. VPS35-deficient mice exhibited PD-relevant deficits including accumulation of α-synuclein in SNpc-DA neurons, loss of DA transmitter and DA neurons in SNpc and STR, and impairment of locomotor behavior. Further mechanical studies showed that VPS35-deficient DA neurons or DA neurons expressing PD-linked VPS35 mutant (D620N) had impaired endosome-to-Golgi retrieval of lysosome-associated membrane glycoprotein 2a (Lamp2a) and accelerated Lamp2a degradation. Expression of Lamp2a in VPS35-deficient DA neurons reduced α-synuclein, supporting the view for Lamp2a as a receptor of chaperone-mediated autophagy to be critical for α-synuclein degradation. These results suggest that VPS35 deficiency or mutation promotes PD pathogenesis and reveals a crucial pathway, VPS35-Lamp2a-α-synuclein, to prevent PD pathogenesis. SIGNIFICANCE STATEMENT VPS35 is a key component of the retromer complex that is essential for endosome-to-Golgi retrieval of membrane proteins. Mutations in the VPS35 gene have been identified in patients with PD. However, if and how VPS35 deficiency or mutation contributes to PD pathogenesis remains unclear. We demonstrated that VPS35 deficiency or mutation (D620N) in mice leads to α-synuclein accumulation and aggregation in the substantia nigra, accompanied with DA neurodegeneration. VPS35-deficient DA neurons exhibit impaired endosome-to-Golgi retrieval of Lamp2a, which may contribute to the reduced α-synuclein degradation through

  7. Brain region-dependent differential expression of alpha-synuclein.

    PubMed

    Taguchi, Katsutoshi; Watanabe, Yoshihisa; Tsujimura, Atsushi; Tanaka, Masaki

    2016-04-15

    α-Synuclein, the major constituent of Lewy bodies (LBs), is normally expressed in presynapses and is involved in synaptic function. Abnormal intracellular aggregation of α-synuclein is observed as LBs and Lewy neurites in neurodegenerative disorders, such as Parkinson's disease (PD) or dementia with Lewy bodies. Accumulated evidence suggests that abundant intracellular expression of α-synuclein is one of the risk factors for pathological aggregation. Recently, we reported differential expression patterns of α-synuclein between excitatory and inhibitory hippocampal neurons. Here we further investigated the precise expression profile in the adult mouse brain with special reference to vulnerable regions along the progression of idiopathic PD. The results show that α-synuclein was highly expressed in the neuronal cell bodies of some early PD-affected brain regions, such as the olfactory bulb, dorsal motor nucleus of the vagus, and substantia nigra pars compacta. Synaptic expression of α-synuclein was mostly accompanied by expression of vesicular glutamate transporter-1, an excitatory presynaptic marker. In contrast, expression of α-synuclein in the GABAergic inhibitory synapses was different among brain regions. α-Synuclein was clearly expressed in inhibitory synapses in the external plexiform layer of the olfactory bulb, globus pallidus, and substantia nigra pars reticulata, but not in the cerebral cortex, subthalamic nucleus, or thalamus. These results suggest that some neurons in early PD-affected human brain regions express high levels of perikaryal α-synuclein, as happens in the mouse brain. Additionally, synaptic profiles expressing α-synuclein are different in various brain regions. © 2015 Wiley Periodicals, Inc.

  8. Serine 129 phosphorylation of membrane-associated α-synuclein modulates dopamine transporter function in a G protein–coupled receptor kinase–dependent manner

    PubMed Central

    Hara, Susumu; Arawaka, Shigeki; Sato, Hiroyasu; Machiya, Youhei; Cui, Can; Sasaki, Asuka; Koyama, Shingo; Kato, Takeo

    2013-01-01

    Most α-synuclein (α-syn) deposited in Lewy bodies, the pathological hallmark of Parkinson disease (PD), is phosphorylated at Ser-129. However, the physiological and pathological roles of this modification are unclear. Here we investigate the effects of Ser-129 phosphorylation on dopamine (DA) uptake in dopaminergic SH-SY5Y cells expressing α-syn. Subcellular fractionation of small interfering RNA (siRNA)–treated cells shows that G protein–coupled receptor kinase 3 (GRK3), GRK5, GRK6, and casein kinase 2 (CK2) contribute to Ser-129 phosphorylation of membrane-associated α-syn, whereas cytosolic α-syn is phosphorylated exclusively by CK2. Expression of wild-type α-syn increases DA uptake, and this effect is diminished by introducing the S129A mutation into α-syn. However, wild-type and S129A α-syn equally increase the cell surface expression of dopamine transporter (DAT) in SH-SY5Y cells and nonneuronal HEK293 cells. In addition, siRNA-mediated knockdown of GRK5 or GRK6 significantly attenuates DA uptake without altering DAT cell surface expression, whereas knockdown of CK2 has no effect on uptake. Taken together, our results demonstrate that membrane-associated α-syn enhances DA uptake capacity of DAT by GRKs-mediated Ser-129 phosphorylation, suggesting that α-syn modulates intracellular DA levels with no functional redundancy in Ser-129 phosphorylation between GRKs and CK2. PMID:23576548

  9. In vitro study of α-synuclein protofibrils by cryo-EM suggests a Cu(2+)-dependent aggregation pathway.

    PubMed

    Zhang, Hangyu; Griggs, Amy; Rochet, Jean-Christophe; Stanciu, Lia A

    2013-06-18

    The aggregation of α-synuclein is thought to play a role in the death of dopamine neurons in Parkinson's disease (PD). Alpha-synuclein transitions itself through an aggregation pathway consisting of pathogenic species referred to as protofibrils (or oligomer), which ultimately convert to mature fibrils. The structural heterogeneity and instability of protofibrils has significantly impeded advance related to the understanding of their structural characteristics and the amyloid aggregation mystery. Here, we report, to our knowledge for the first time, on α-synuclein protofibril structural characteristics with cryo-electron microscopy. Statistical analysis of annular protofibrils revealed a constant wall thickness as a common feature. The visualization of the assembly steps enabled us to propose a novel, to our knowledge, mechanisms for α-synuclein aggregation involving ring-opening and protofibril-protofibril interaction events. The ion channel-like protofibrils and their membrane permeability have also been found in other amyloid diseases, suggesting a common molecular mechanism of pathological aggregation. Our direct visualization of the aggregation pathway of α-synuclein opens up fresh opportunities to advance the understanding of protein aggregation mechanisms relevant to many amyloid diseases. In turn, this information would enable the development of additional therapeutic strategies aimed at suppressing toxic protofibrils of amyloid proteins involved in neurological disorders. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. Severely impaired hippocampal neurogenesis associates with an early serotonergic deficit in a BAC α-synuclein transgenic rat model of Parkinson's disease

    PubMed Central

    Kohl, Zacharias; Abdallah, Nada Ben; Vogelgsang, Jonathan; Tischer, Lucas; Deusser, Janina; Amato, Davide; Anderson, Scott; Müller, Christian P.; Riess, Olaf; Masliah, Eliezer; Nuber, Silke; Winkler, Jürgen

    2016-01-01

    Parkinson's disease (PD) is a multisystem disorder, involving several monoaminergic neurotransmitter systems resulting in a broad range of motor and non-motor symptoms. Pathological hallmarks of PD are the loss of dopaminergic neurons and the accumulation of alpha-synuclein, however also being present in the serotonergic raphe nuclei early in the disease course. The dysfunction of the serotonergic system projecting to the hippocampus might contribute to early non-motor symptoms such as anxiety and depression. The adult hippocampal dentate gyrus (DG), a unique niche of the forebrain continuously generating new neurons, may particularly present enhanced susceptibility towards accumulating alpha-synuclein levels. The underlying molecular mechanisms in the context of neuronal maturation and survival of new-born neurons are yet not well understood. To characterize the effects of overexpression of human full-length alpha-synuclein on hippocampal cellular and synaptic plasticity, we used a recently generated BAC alpha-synuclein transgenic rat model showing important features of PD such as widespread and progressive alpha-synuclein aggregation pathology, dopamine loss and age-dependent motor decline. At the age of four months, thus prior to the occurrence of the motor phenotype, we observed a profoundly impaired dendritogenesis of neuroblasts in the hippocampal DG resulting in severely reduced survival of adult new-born neurons. Diminished neurogenesis concurred with a serotonergic deficit in the hippocampus as defined by reduced levels of serotonin (5-HT) 1B receptor, decreased 5-HT neurotransmitter levels, and a loss of serotonergic nerve terminals innervating the DG/CA3 subfield, while the number of serotonergic neurons in the raphe nuclei remained unchanged. Moreover, alpha-synuclein overexpression reduced proteins involved in vesicle release, in particular synapsin-1 and Rab3 interacting molecule (RIM3), in conjunction with an altered ultrastructural architecture of

  11. A rationally designed six-residue swap generates comparability in the aggregation behavior of α-synuclein and β-synuclein.

    PubMed

    Roodveldt, Cintia; Andersson, August; De Genst, Erwin J; Labrador-Garrido, Adahir; Buell, Alexander K; Dobson, Christopher M; Tartaglia, Gian Gaetano; Vendruscolo, Michele

    2012-11-06

    The aggregation process of α-synuclein, a protein closely associated with Parkinson's disease, is highly sensitive to sequence variations. It is therefore of great importance to understand the factors that define the aggregation propensity of specific mutational variants as well as their toxic behavior in the cellular environment. In this context, we investigated the extent to which the aggregation behavior of α-synuclein can be altered to resemble that of β-synuclein, an aggregation-resistant homologue of α-synuclein not associated with disease, by swapping residues between the two proteins. Because of the vast number of possible swaps, we have applied a rational design procedure to single out a mutational variant, called α2β, in which two short stretches of the sequence in the NAC region have been replaced in α-synuclein from β-synuclein. We find not only that the aggregation rate of α2β is close to that of β-synuclein, being much lower than that of α-synuclein, but also that α2β effectively changes the cellular toxicity of α-synuclein to a value similar to that of β-synuclein upon exposure of SH-SY5Y cells to preformed oligomers. Remarkably, control experiments on the corresponding mutational variant of β-synuclein, called β2α, confirmed that the mutations that we have identified also shift the aggregation behavior of this protein toward that of α-synuclein. These results demonstrate that it is becoming possible to control in quantitative detail the sequence code that defines the aggregation behavior and toxicity of α-synuclein.

  12. Immunotherapy targeting α-synuclein protofibrils reduced pathology in (Thy-1)-h[A30P] α-synuclein mice.

    PubMed

    Lindström, Veronica; Fagerqvist, Therese; Nordström, Eva; Eriksson, Fredrik; Lord, Anna; Tucker, Stina; Andersson, Jessica; Johannesson, Malin; Schell, Heinrich; Kahle, Philipp J; Möller, Christer; Gellerfors, Pär; Bergström, Joakim; Lannfelt, Lars; Ingelsson, Martin

    2014-09-01

    Several lines of evidence suggest that accumulation of aggregated alpha-synuclein (α-synuclein) in the central nervous system (CNS) is an early pathogenic event in Parkinson's disease and other Lewy body disorders. In recent years, animal studies have indicated immunotherapy with antibodies directed against α-synuclein as a promising novel treatment strategy. Since large α-synuclein oligomers, or protofibrils, have been demonstrated to possess pronounced cytotoxic properties, such species should be particularly attractive as therapeutic targets. In support of this, (Thy-1)-h[A30P] α-synuclein transgenic mice with motor dysfunction symptoms were found to display increased levels of α-synuclein protofibrils in the CNS. An α-synuclein protofibril-selective monoclonal antibody (mAb47) was evaluated in this α-synuclein transgenic mouse model. As measured by ELISA, 14month old mice treated for 14weeks with weekly intraperitoneal injections of mAb47 displayed significantly lower levels of both soluble and membrane-associated protofibrils in the spinal cord. Besides the lower levels of pathogenic α-synuclein demonstrated, a reduction of motor dysfunction in transgenic mice upon peripheral administration of mAb47 was indicated. Thus, immunotherapy with antibodies targeting toxic α-synuclein species holds promise as a future disease-modifying treatment in Parkinson's disease and related disorders. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. The N-Terminal Residues 43 to 60 Form the Interface for Dopamine Mediated α-Synuclein Dimerisation

    PubMed Central

    Leong, Su Ling; Hinds, Mark G.; Connor, Andrea R.; Smith, David P.; Illes-Toth, Eva; Pham, Chi L. L.; Barnham, Kevin J.; Cappai, Roberto

    2015-01-01

    α-synuclein (α-syn) is a major component of the intracellular inclusions called Lewy bodies, which are a key pathological feature in the brains of Parkinson’s disease patients. The neurotransmitter dopamine (DA) inhibits the fibrillisation of α-syn into amyloid, and promotes α-syn aggregation into SDS-stable soluble oligomers. While this inhibition of amyloid formation requires the oxidation of both DA and the methionines in α-syn, the molecular basis for these processes is still unclear. This study sought to define the protein sequences required for the generation of oligomers. We tested N- (α-syn residues 43–140) and C-terminally (1–95) truncated α-syn, and found that similar to full-length protein both truncated species formed soluble DA:α-syn oligomers, albeit 1–95 had a different profile. Using nuclear magnetic resonance (NMR), and the N-terminally truncated α-syn 43–140 protein, we analysed the structural characteristics of the DA:α-syn 43–140 dimer and α-syn 43–140 monomer and found the dimerisation interface encompassed residues 43 to 60. Narrowing the interface to this small region will help define the mechanism by which DA mediates the formation of SDS-stable soluble DA:α-syn oligomers. PMID:25679387

  14. Treatment with Trehalose Prevents Behavioral and Neurochemical Deficits Produced in an AAV α-Synuclein Rat Model of Parkinson's Disease.

    PubMed

    He, Qing; Koprich, James B; Wang, Ying; Yu, Wen-bo; Xiao, Bao-guo; Brotchie, Jonathan M; Wang, Jian

    2016-05-01

    The accumulation of misfolded α-synuclein in dopamine (DA) neurons is believed to be of major importance in the pathogenesis of Parkinson's disease (PD). Animal models of PD, based on viral-vector-mediated over-expression of α-synuclein, have been developed and show evidence of dopaminergic toxicity, providing us a good tool to investigate potential therapies to interfere with α-synuclein-mediated pathology. An efficient disease-modifying therapeutic molecule should be able to interfere with the neurotoxicity of α-synuclein aggregation. Our study highlighted the ability of an autophagy enhancer, trehalose (at concentrations of 5 and 2% in drinking water), to protect against A53T α-synuclein-mediated DA degeneration in an adeno-associated virus serotype 1/2 (AAV1/2)-based rat model of PD. Behavioral tests and neurochemical analysis demonstrated a significant attenuation in α-synuclein-mediated deficits in motor asymmetry and DA neurodegeneration including impaired DA neuronal survival and DA turnover, as well as α-synuclein accumulation and aggregation in the nigrostriatal system by commencing 5 and 2% trehalose at the same time as delivery of AAV. Trehalose (0.5%) was ineffective on the above behavioral and neurochemical deficits. Further investigation showed that trehalose enhanced autophagy in the striatum by increasing formation of LC3-II. This study supports the concept of using trehalose as a novel therapeutic strategy that might prevent/reverse α-synuclein aggregation for the treatment of PD.

  15. Glycation potentiates α-synuclein-associated neurodegeneration in synucleinopathies.

    PubMed

    Vicente Miranda, Hugo; Szego, Éva M; Oliveira, Luís M A; Breda, Carlo; Darendelioglu, Ekrem; de Oliveira, Rita M; Ferreira, Diana G; Gomes, Marcos A; Rott, Ruth; Oliveira, Márcia; Munari, Francesca; Enguita, Francisco J; Simões, Tânia; Rodrigues, Eva F; Heinrich, Michael; Martins, Ivo C; Zamolo, Irina; Riess, Olaf; Cordeiro, Carlos; Ponces-Freire, Ana; Lashuel, Hilal A; Santos, Nuno C; Lopes, Luisa V; Xiang, Wei; Jovin, Thomas M; Penque, Deborah; Engelender, Simone; Zweckstetter, Markus; Klucken, Jochen; Giorgini, Flaviano; Quintas, Alexandre; Outeiro, Tiago F

    2017-05-01

    α-Synuclein misfolding and aggregation is a hallmark in Parkinson's disease and in several other neurodegenerative diseases known as synucleinopathies. The toxic properties of α-synuclein are conserved from yeast to man, but the precise underpinnings of the cellular pathologies associated are still elusive, complicating the development of effective therapeutic strategies. Combining molecular genetics with target-based approaches, we established that glycation, an unavoidable age-associated post-translational modification, enhanced α-synuclein toxicity in vitro and in vivo, in Drosophila and in mice. Glycation affected primarily the N-terminal region of α-synuclein, reducing membrane binding, impaired the clearance of α-synuclein, and promoted the accumulation of toxic oligomers that impaired neuronal synaptic transmission. Strikingly, using glycation inhibitors, we demonstrated that normal clearance of α-synuclein was re-established, aggregation was reduced, and motor phenotypes in Drosophila were alleviated. Altogether, our study demonstrates glycation constitutes a novel drug target that can be explored in synucleinopathies as well as in other neurodegenerative conditions. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Synucleins: are they two-edged swords?

    PubMed

    Surguchov, Andrei

    2013-02-01

    The synuclein family consists of three distinct highly homologous genes, α-synuclein, β-synuclein, and γ-synuclein, which have so far been found only in vertebrates. Proteins encoded by these genes are characterized by an acidic C-terminal region and five or six imperfect repeat motifs (KTKEGV) distributed throughout the highly conserved N-terminal region. Numerous data demonstrate that synucleins are implicated in two groups of the most devastating human disorders, i.e., neurodegenerative diseases (NDDs) and cancer. Mutations in the α-synuclein gene are associated with familial forms of Parkinson's disease (PD), and accumulation of α-synuclein inclusions is a hallmark of this disorder. In breast cancer, increased expression of γ-synuclein correlates with disease progression. Conversely, some results indicate that the members of the synuclein family may have a protective effect. How might these small proteins combine such controversial properties? We present evidence that synuclein's features are basically regulated by two mechanisms, i.e., posttranslational modifications (PTMs) and the level of their expression. We also discuss a new, emerging area of investigation of synucleins, namely, their role in the cell-to-cell propagation of pathology. Copyright © 2012 Wiley Periodicals, Inc.

  17. Alpha-synuclein Toxicity in the Early Secretory Pathway: How It Drives Neurodegeneration in Parkinsons Disease

    PubMed Central

    Wang, Ting; Hay, Jesse C.

    2015-01-01

    Alpha-synuclein is a predominant player in the pathogenesis of Parkinson's Disease. However, despite extensive study for two decades, its physiological and pathological mechanisms remain poorly understood. Alpha-synuclein forms a perplexing web of interactions with lipids, trafficking machinery, and other regulatory factors. One emerging consensus is that synaptic vesicles are likely the functional site for alpha-synuclein, where it appears to facilitate vesicle docking and fusion. On the other hand, the dysfunctions of alpha-synuclein are more dispersed and numerous; when mutated or over-expressed, alpha-synuclein affects several membrane trafficking and stress pathways, including exocytosis, ER-to-Golgi transport, ER stress, Golgi homeostasis, endocytosis, autophagy, oxidative stress, and others. Here we examine recent developments in alpha-synuclein's toxicity in the early secretory pathway placed in the context of emerging themes from other affected pathways to help illuminate its underlying pathogenic mechanisms in neurodegeneration. PMID:26617485

  18. Alpha-synuclein aggregation induced by brief ischemia negatively impacts neuronal survival in vivo: a study in [A30P]alpha-synuclein transgenic mouse

    PubMed Central

    Unal-Cevik, Isin; Gursoy-Ozdemir, Yasemin; Yemisci, Muge; Lule, Sevda; Gurer, Gunfer; Can, Alp; Müller, Veronica; Kahle, Philip J; Dalkara, Turgay

    2011-01-01

    Alpha-synuclein oligomerization and aggregation are considered to have a role in the pathogenesis of neurodegenerative diseases. However, despite numerous in vitro studies, the impact of aggregates in the intact brain is unclear. In vitro, oxidative/nitrative stress and acidity induce α-synuclein oligomerization. These conditions favoring α-synuclein fibrillization are present in the ischemic brain, which may serve as an in vivo model to study α-synuclein aggregation. In this study, we show that 30-minute proximal middle cerebral artery (MCA) occlusion and 72 hours reperfusion induce oligomerization of wild-type α-synuclein in the ischemic mouse brain. The nonamyloidogenic isoform β-synuclein did not form oligomers. Alpha-synuclein aggregates were confined to neurons and colocalized with ubiquitin immunoreactivity. We also found that 30 minutes proximal MCA occlusion and 24 hours reperfusion induced larger infarcts in C57BL/6(Thy1)-h[A30P]alphaSYN transgenic mice, which have an increased tendency to form synuclein fibrils. Trangenics also developed more selective neuronal necrosis when subjected to 20 minutes distal MCA occlusion and 72 hours reperfusion. Enhanced 3-nitrotyrosine immunoreactivity in transgenic mice suggests that oxidative/nitrative stress may be one of the mechanisms mediating aggregate toxicity. Thus, the increased vulnerability of transgenic mice to ischemia suggests that α-synuclein aggregates not only form during ischemia but also negatively impact neuronal survival, supporting the idea that α-synuclein misfolding may be neurotoxic. PMID:20877387

  19. Monomeric Alpha-Synuclein Exerts a Physiological Role on Brain ATP Synthase

    PubMed Central

    Ludtmann, Marthe H.R.; Angelova, Plamena R.; Ninkina, Natalia N.; Gandhi, Sonia

    2016-01-01

    Misfolded α-synuclein is a key factor in the pathogenesis of Parkinson's disease (PD). However, knowledge about a physiological role for the native, unfolded α-synuclein is limited. Using brains of mice lacking α-, β-, and γ-synuclein, we report that extracellular monomeric α-synuclein enters neurons and localizes to mitochondria, interacts with ATP synthase subunit α, and modulates ATP synthase function. Using a combination of biochemical, live-cell imaging and mitochondrial respiration analysis, we found that brain mitochondria of α-, β-, and γ-synuclein knock-out mice are uncoupled, as characterized by increased mitochondrial respiration and reduced mitochondrial membrane potential. Furthermore, synuclein deficiency results in reduced ATP synthase efficiency and lower ATP levels. Exogenous application of low unfolded α-synuclein concentrations is able to increase the ATP synthase activity that rescues the mitochondrial phenotypes observed in synuclein deficiency. Overall, the data suggest that α-synuclein is a previously unrecognized physiological regulator of mitochondrial bioenergetics through its ability to interact with ATP synthase and increase its efficiency. This may be of particular importance in times of stress or PD mutations leading to energy depletion and neuronal cell toxicity. SIGNIFICANCE STATEMENT Misfolded α-synuclein aggregations in the form of Lewy bodies have been shown to be a pathological hallmark in histological staining of Parkinson's disease (PD) patient brains. It is known that misfolded α-synuclein is a key driver in PD pathogenesis, but the physiological role of unfolded monomeric α-synuclein remains unclear. Using neuronal cocultures and isolated brain mitochondria of α-, β-, and γ-synuclein knock-out mice and monomeric α-synuclein, this current study shows that α-synuclein in its unfolded monomeric form improves ATP synthase efficiency and mitochondrial function. The ability of monomeric α-synuclein to enhance

  20. Alpha-synuclein aggregates activate calcium pump SERCA leading to calcium dysregulation.

    PubMed

    Betzer, Cristine; Lassen, Louise Berkhoudt; Olsen, Anders; Kofoed, Rikke Hahn; Reimer, Lasse; Gregersen, Emil; Zheng, Jin; Calì, Tito; Gai, Wei-Ping; Chen, Tong; Moeller, Arne; Brini, Marisa; Fu, Yuhong; Halliday, Glenda; Brudek, Tomasz; Aznar, Susana; Pakkenberg, Bente; Andersen, Jens Peter; Jensen, Poul Henning

    2018-05-01

    Aggregation of α-synuclein is a hallmark of Parkinson's disease and dementia with Lewy bodies. We here investigate the relationship between cytosolic Ca 2+ and α-synuclein aggregation. Analyses of cell lines and primary culture models of α-synuclein cytopathology reveal an early phase with reduced cytosolic Ca 2+ levels followed by a later Ca 2+ increase. Aggregated but not monomeric α-synuclein binds to and activates SERCA in vitro , and proximity ligation assays confirm this interaction in cells. The SERCA inhibitor cyclopiazonic acid (CPA) normalises both the initial reduction and the later increase in cytosolic Ca 2+ CPA protects the cells against α-synuclein-aggregate stress and improves viability in cell models and in Caenorhabditis elegans in vivo Proximity ligation assays also reveal an increased interaction between α-synuclein aggregates and SERCA in human brains affected by dementia with Lewy bodies. We conclude that α-synuclein aggregates bind SERCA and stimulate its activity. Reducing SERCA activity is neuroprotective, indicating that SERCA and down-stream processes may be therapeutic targets for treating α-synucleinopathies. © 2018 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

  1. Seeking a Mechanism for the Toxicity of Oligomeric α-Synuclein

    PubMed Central

    Roberts, Hazel L.; Brown, David R.

    2015-01-01

    In a number of neurological diseases including Parkinson’s disease (PD), α‑synuclein is aberrantly folded, forming abnormal oligomers, and amyloid fibrils within nerve cells. Strong evidence exists for the toxicity of increased production and aggregation of α-synuclein in vivo. The toxicity of α-synuclein is popularly attributed to the formation of “toxic oligomers”: a heterogenous and poorly characterized group of conformers that may share common molecular features. This review presents the available evidence on the properties of α-synuclein oligomers and the potential molecular mechanisms of their cellular disruption. Toxic α-synuclein oligomers may impact cells in a number of ways, including the disruption of membranes, mitochondrial depolarization, cytoskeleton changes, impairment of protein clearance pathways, and enhanced oxidative stress. We also examine the relationship between α-synuclein toxic oligomers and amyloid fibrils, in the light of recent studies that paint a more complex picture of α-synuclein toxicity. Finally, methods of studying and manipulating oligomers within cells are described. PMID:25816357

  2. O-GlcNAc modification blocks the aggregation and toxicity of the protein α-synuclein associated with Parkinson's disease

    NASA Astrophysics Data System (ADS)

    Marotta, Nicholas P.; Lin, Yu Hsuan; Lewis, Yuka E.; Ambroso, Mark R.; Zaro, Balyn W.; Roth, Maxwell T.; Arnold, Don B.; Langen, Ralf; Pratt, Matthew R.

    2015-11-01

    Several aggregation-prone proteins associated with neurodegenerative diseases can be modified by O-linked N-acetyl-glucosamine (O-GlcNAc) in vivo. One of these proteins, α-synuclein, is a toxic aggregating protein associated with synucleinopathies, including Parkinson's disease. However, the effect of O-GlcNAcylation on α-synuclein is not clear. Here, we use synthetic protein chemistry to generate both unmodified α-synuclein and α-synuclein bearing a site-specific O-GlcNAc modification at the physiologically relevant threonine residue 72. We show that this single modification has a notable and substoichiometric inhibitory effect on α-synuclein aggregation, while not affecting the membrane binding or bending properties of α-synuclein. O-GlcNAcylation is also shown to affect the phosphorylation of α-synuclein in vitro and block the toxicity of α-synuclein that was exogenously added to cells in culture. These results suggest that increasing O-GlcNAcylation may slow the progression of synucleinopathies and further support a general function for O-GlcNAc in preventing protein aggregation.

  3. Inflammation kinase PKR phosphorylates α-synuclein and causes α-synuclein-dependent cell death.

    PubMed

    Reimer, Lasse; Vesterager, Louise Buur; Betzer, Cristine; Zheng, Jin; Nielsen, Lærke Dalsgaard; Kofoed, Rikke Hahn; Lassen, Louise Berkhoudt; Bølcho, Ulrik; Paludan, Søren Riis; Fog, Karina; Jensen, Poul Henning

    2018-07-01

    Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy comprise a group of neurodegenerative diseases termed synucleinopathies. Synucleinopathie are, characterized by presence of inclusion bodies in degenerating brain cells which contain aggregated α-synuclein phosphorylated on Ser129. Although the inflammation-associated serine-threonine kinase, PKR (EIF2AK2), promotes cellular protection against infection, we demonstrate a pro-degenerative role of activated PKR in an α-synuclein-dependent cell model of multiple system atrophy, where inhibition and silencing of PKR decrease cellular degeneration. In vitro phosphorylation demonstrates that PKR can directly bind and phosphorylate monomeric and filamenteous α-synuclein on Ser129. Inhibition and knockdown of PKR reduce Ser129 phosphorylation in different models (SH-SY5Y ASYN cells, OLN-AS7 cells, primary mouse hippocampal neurons, and acute brain slices), while overexpression of constitutively active PKR increases Ser129 α-syn phosphorylation. Treatment with pre-formed α-synuclein fibrils, proteostatic stress-promoting MG-132 and known PKR activators, herpes simplex virus-1-∆ICP34.5 and LPS, as well as PKR inducer, IFN-β-1b, lead to increased levels of phosphorylated Ser129 α-synuclein that is completely blocked by simultaneous PKR inhibition. These results reveal a direct link between PKR and the phosphorylation and toxicity of α-synuclein, and they support that neuroinflammatory processes play a role in modulating the pathogenicity of α-synuclein. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. α-Synuclein Regulates Neuronal Cholesterol Efflux.

    PubMed

    Hsiao, Jen-Hsiang T; Halliday, Glenda M; Kim, Woojin Scott

    2017-10-19

    α-Synuclein is a neuronal protein that is at the center of focus in understanding the etiology of a group of neurodegenerative diseases called α-synucleinopathies, which includes Parkinson's disease (PD). Despite much research, the exact physiological function of α-synuclein is still unclear. α-Synuclein has similar biophysical properties as apolipoproteins and other lipid-binding proteins and has a high affinity for cholesterol. These properties suggest a possible role for α-synuclein as a lipid acceptor mediating cholesterol efflux (the process of removing cholesterol out of cells). To test this concept, we "loaded" SK-N-SH neuronal cells with fluorescently-labelled cholesterol, applied exogenous α-synuclein, and measured the amount of cholesterol removed from the cells using a classic cholesterol efflux assay. We found that α-synuclein potently stimulated cholesterol efflux. We found that the process was dose and time dependent, and was saturable at 1.0 µg/mL of α-synuclein. It was also dependent on the transporter protein ABCA1 located on the plasma membrane. We reveal for the first time a novel role of α-synuclein that underscores its importance in neuronal cholesterol regulation, and identify novel therapeutic targets for controlling cellular cholesterol levels.

  5. Brain propagation of transduced α-synuclein involves non-fibrillar protein species and is enhanced in α-synuclein null mice.

    PubMed

    Helwig, Michael; Klinkenberg, Michael; Rusconi, Raffaella; Musgrove, Ruth E; Majbour, Nour K; El-Agnaf, Omar M A; Ulusoy, Ayse; Di Monte, Donato A

    2016-03-01

    Aggregation and neuron-to-neuron transmission are attributes of α-synuclein relevant to its pathogenetic role in human synucleinopathies such as Parkinson's disease. Intraparenchymal injections of fibrillar α-synuclein trigger widespread propagation of amyloidogenic protein species via mechanisms that require expression of endogenous α-synuclein and, possibly, its structural corruption by misfolded conformers acting as pathological seeds. Here we describe another paradigm of long-distance brain diffusion of α-synuclein that involves inter-neuronal transfer of monomeric and/or oligomeric species and is independent of recruitment of the endogenous protein. Targeted expression of human α-synuclein was induced in the mouse medulla oblongata through an injection of viral vectors into the vagus nerve. Enhanced levels of intra-neuronal α-synuclein were sufficient to initiate its caudo-rostral diffusion that likely involved at least one synaptic transfer and progressively reached specific brain regions such as the locus coeruleus, dorsal raphae and amygdala in the pons, midbrain and forebrain. Transfer of human α-synuclein was compared in two separate lines of α-synuclein-deficient mice versus their respective wild-type controls and, interestingly, lack of endogenous α-synuclein expression did not counteract diffusion but actually resulted in a more pronounced and advanced propagation of exogenous α-synuclein. Self-interaction of adjacent molecules of human α-synuclein was detected in both wild-type and mutant mice. In the former, interaction of human α-synuclein with mouse α-synuclein was also observed and might have contributed to differences in protein transmission. In wild-type and α-synuclein-deficient mice, accumulation of human α-synuclein within recipient axons in the pons, midbrain and forebrain caused morphological evidence of neuritic pathology. Tissue sections from the medulla oblongata and pons were stained with different antibodies recognizing

  6. Applying chaperones to protein-misfolding disorders: molecular chaperones against α-synuclein in Parkinson's disease.

    PubMed

    Chaari, Ali; Hoarau-Véchot, Jessica; Ladjimi, Moncef

    2013-09-01

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by the accumulation of a protein called α-synuclein (α-syn) into inclusions known as lewy bodies (LB) within neurons. This accumulation is also due to insufficient formation and activity of dopamine produced in certain neurons within the substantia nigra. Lewy bodies are the pathological hallmark of the idiopathic disorder and the cascade that allows α-synuclein to misfold, aggregate and form these inclusions has been the subject of intensive research. Targeting these early steps of oligomerization is one of the main therapeutic approaches in order to develop neurodegenerative-modifying agents. Because the folding and refolding of alpha synuclein is the key point of this cascade, we are interested in this review to summarize the role of some molecular chaperones proteins such as Hsp70, Hsp90 and small heat shock proteins (sHsp) and Hsp 104. Hsp70 and its co-chaperone, Hsp70 and small heat shock proteins can prevent neurodegeneration by preventing α-syn misfolding, oligomerization and aggregation in vitro and in Parkinson disease animal models. Hsp104 is able to resolve disordered protein aggregates and cross beta amyloid conformers. Together, these chaperones have a complementary effect and can be a target for therapeutic intervention in PD. Published by Elsevier B.V.

  7. Cell Biology and Pathophysiology of α-Synuclein

    PubMed Central

    Burré, Jacqueline; Sharma, Manu; Südhof, Thomas C.

    2017-01-01

    α-Synuclein is an abundant neuronal protein that is highly enriched in presynaptic nerve terminals. Genetics and neuropathology studies link α-synuclein to Parkinson’s disease (PD) and other neurodegenerative disorders. Accumulation of misfolded oligomers and larger aggregates of α-synuclein defines multiple neurodegenerative diseases called synucleino-pathies, but the mechanisms by which α-synuclein acts in neurodegeneration are unknown. Moreover, the normal cellular function of α-synuclein remains debated. In this perspective, we review the structural characteristics of α-synuclein, its developmental expression pattern, its cellular and subcellular localization, and its function in neurons. We also discuss recent progress on secretion of α-synuclein, which may contribute to its interneuronal spread in a prion-like fashion, and describe the neurotoxic effects of α-synuclein that are thought to be responsible for its role in neurodegeneration. PMID:28108534

  8. Lysosomal response in relation to α-synuclein pathology differs between Parkinson's disease and multiple system atrophy.

    PubMed

    Puska, Gina; Lutz, Mirjam I; Molnar, Kinga; Regelsberger, Günther; Ricken, Gerda; Pirker, Walter; Laszlo, Lajos; Kovacs, Gabor G

    2018-06-01

    Intracellular deposition of pathologically altered α-synuclein mostly in neurons characterises Parkinson's disease (PD), while its accumulation predominantly in oligodendrocytes is a feature of multiple system atrophy (MSA). Recently a prion-like spreading of pathologic α-synuclein has been suggested to play a role in the pathogenesis of PD and MSA. This implicates a role of protein processing systems, including lysosomes, supported also by genetic studies in PD. However, particularly for MSA, the mechanism of cell-to-cell propagation of α-synuclein is yet not fully understood. To evaluate the significance of lysosomal response, we systematically compared differently affected neuronal populations in PD, MSA, and non-diseased brains using morphometric immunohistochemistry (cathepsin D), double immunolabelling (cathepsin D/α-synuclein) laser confocal microscopy, and immunogold electron microscopy for the disease associated α-synuclein. We found that i) irrespective of the presence of neuronal inclusions, the volume density of cathepsin D immunoreactivity significantly increases in affected neurons of the pontine base in MSA brains; ii) volume density of cathepsin D immunoreactivity increases in nigral neurons in PD without inclusions and with non-ubiquitinated pre-aggregates of α-synuclein, but not in neurons with Lewy bodies; iii) cathepsin D immunoreactivity frequently colocalises with α-synuclein pre-aggregates in nigral neurons in PD; iv) ultrastructural observations confirm disease-associated α-synuclein in neuronal and astrocytic lysosomes in PD; v) lysosome-associated α-synuclein is observed in astroglia and rarely in oligodendroglia and in neurons in MSA. Our observations support a crucial role for the neuronal endosomal-lysosomal system in the processing of α-synuclein in PD. We suggest a distinct contribution of lysosomes to the pathogenesis of MSA, including the possibility of oligodendroglial and eventually neuronal uptake of exogenous α-synuclein

  9. Genetic and pharmacological evidence that endogenous nociceptin/orphanin FQ contributes to dopamine cell loss in Parkinson's disease.

    PubMed

    Arcuri, Ludovico; Viaro, Riccardo; Bido, Simone; Longo, Francesco; Calcagno, Mariangela; Fernagut, Pierre-Olivier; Zaveri, Nurulain T; Calò, Girolamo; Bezard, Erwan; Morari, Michele

    2016-05-01

    To investigate whether the endogenous neuropeptide nociceptin/orphanin FQ (N/OFQ) contributes to the death of dopamine neurons in Parkinson's disease, we undertook a genetic and a pharmacological approach using NOP receptor knockout (NOP(-/-)) mice, and the selective and potent small molecule NOP receptor antagonist (-)-cis-1-methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol (SB-612111). Stereological unbiased methods were used to estimate the total number of dopamine neurons in the substantia nigra of i) NOP(-/-) mice acutely treated with the parkinsonian neurotoxin 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP), ii) naïve mice subacutely treated with MPTP, alone or in combination with SB-612111, iii) rats injected with a recombinant adeno-associated viral (AAV) vector overexpressing human mutant p.A53T α-synuclein, treated with vehicle or SB-612111. NOP(-/-) mice showed a 50% greater amount of nigral dopamine neurons spared in response to acute MPTP compared to controls, which was associated with a milder motor impairment. SB-612111, given 4 days after MPTP treatment to mimic the clinical condition, prevented the loss of nigral dopamine neurons and striatal dopaminergic terminals caused by subacute MPTP. SB-612111, administered a week after the AAV injections in a clinically-driven protocol, also increased by 50% both the number of spared nigral dopamine neurons and striatal dopamine terminals, and prevented accompanying motor deficits induced by α-synuclein. We conclude that endogenous N/OFQ contributes to dopamine neuron loss in pathogenic and etiologic models of Parkinson's disease through NOP receptor-mediated mechanisms. NOP receptor antagonists might prove effective as disease-modifying agents in Parkinson's disease, through the rescue of degenerating nigral dopamine neurons and/or the protection of the healthy ones. Copyright © 2016. Published by Elsevier Inc.

  10. Dopamine Precursor Depletion Influences Pain Affect Rather than Pain Sensation

    PubMed Central

    Schulz, Enrico; Baumkötter, Jochen; Ploner, Markus

    2014-01-01

    Pain is a multidimensional experience, which includes sensory, cognitive, and affective aspects. Converging lines of evidence indicate that dopaminergic neurotransmission plays an important role in human pain perception. However, the precise effects of dopamine on different aspects of pain perception remain to be elucidated. To address this question, we experimentally decreased dopaminergic neurotransmission in 22 healthy human subjects using Acute Phenylalanine and Tyrosine Depletion (APTD). During APTD and a control condition we applied brief painful laser stimuli to the hand, assessed different aspects of pain perception, and recorded electroencephalographic responses. APTD-induced decreases of cerebral dopaminergic activity did not influence sensory aspects of pain perception. In contrast, APTD yielded increases of pain unpleasantness. The increases of unpleasantness ratings positively correlated with effectiveness of APTD. Our finding of an influence of dopaminergic neurotransmission on affective but not sensory aspects of phasic pain suggests that analgesic effects of dopamine might be mediated by indirect effects on pain affect rather than by direct effects on ascending nociceptive signals. These findings contribute to our understanding of the complex relationship between dopamine and pain perception, which may play a role in various clinical pain states. PMID:24760082

  11. Novel One-step Immunoassays to Quantify α-Synuclein

    PubMed Central

    Bidinosti, Michael; Shimshek, Derya R.; Mollenhauer, Brit; Marcellin, David; Schweizer, Tatjana; Lotz, Gregor P.; Schlossmacher, Michael G.; Weiss, Andreas

    2012-01-01

    Familial Parkinson disease (PD) can result from α-synuclein gene multiplication, implicating the reduction of neuronal α-synuclein as a therapeutic target. Moreover, α-synuclein content in human cerebrospinal fluid (CSF) represents a PD biomarker candidate. However, capture-based assays for α-synuclein quantification in CSF (such as by ELISA) have shown discrepancies and have limited suitability for high-throughput screening. Here, we describe two sensitive, in-solution, time-resolved Förster's resonance energy transfer (TR-FRET)-based immunoassays for total and oligomeric α-synuclein quantification. CSF analysis showed strong concordance for total α-synuclein content between two TR-FRET assays and, in agreement with a previously characterized 36 h protocol-based ELISA, demonstrated lower α-synuclein levels in PD donors. Critically, the assay suitability for high-throughput screening of siRNA constructs and small molecules aimed at reducing endogenous α-synuclein levels was established and validated. In a small-scale proof of concept compound screen using 384 well plates, signals ranged from <30 to >120% of the mean of vehicle-treated cells for molecules known to lower and increase cellular α-synuclein, respectively. Furthermore, a reverse genetic screen of a kinase-directed siRNA library identified seven genes that modulated α-synuclein protein levels (five whose knockdown increased and two that decreased cellular α-synuclein protein). This provides critical new biological insight into cellular pathways regulating α-synuclein steady-state expression that may help guide further drug discovery efforts. Moreover, we describe an inherent limitation in current α-synuclein oligomer detection methodology, a finding that will direct improvement of future assay design. Our one-step TR-FRET-based platform for α-synuclein quantification provides a novel platform with superior performance parameters for the rapid screening of large biomarker cohorts and of

  12. Synaptic vesicle glycoprotein 2C (SV2C) modulates dopamine release and is disrupted in Parkinson disease.

    PubMed

    Dunn, Amy R; Stout, Kristen A; Ozawa, Minagi; Lohr, Kelly M; Hoffman, Carlie A; Bernstein, Alison I; Li, Yingjie; Wang, Minzheng; Sgobio, Carmelo; Sastry, Namratha; Cai, Huaibin; Caudle, W Michael; Miller, Gary W

    2017-03-14

    Members of the synaptic vesicle glycoprotein 2 (SV2) family of proteins are involved in synaptic function throughout the brain. The ubiquitously expressed SV2A has been widely implicated in epilepsy, although SV2C with its restricted basal ganglia distribution is poorly characterized. SV2C is emerging as a potentially relevant protein in Parkinson disease (PD), because it is a genetic modifier of sensitivity to l-DOPA and of nicotine neuroprotection in PD. Here we identify SV2C as a mediator of dopamine homeostasis and report that disrupted expression of SV2C within the basal ganglia is a pathological feature of PD. Genetic deletion of SV2C leads to reduced dopamine release in the dorsal striatum as measured by fast-scan cyclic voltammetry, reduced striatal dopamine content, disrupted α-synuclein expression, deficits in motor function, and alterations in neurochemical effects of nicotine. Furthermore, SV2C expression is dramatically altered in postmortem brain tissue from PD cases but not in Alzheimer disease, progressive supranuclear palsy, or multiple system atrophy. This disruption was paralleled in mice overexpressing mutated α-synuclein. These data establish SV2C as a mediator of dopamine neuron function and suggest that SV2C disruption is a unique feature of PD that likely contributes to dopaminergic dysfunction.

  13. Mechanisms of α-Synuclein Induced Synaptopathy in Parkinson's Disease

    PubMed Central

    Bridi, Jessika C.; Hirth, Frank

    2018-01-01

    Parkinson's disease (PD) is characterized by intracellular inclusions of aggregated and misfolded α-Synuclein (α-Syn), and the loss of dopaminergic (DA) neurons in the brain. The resulting motor abnormalities mark the progression of PD, while non-motor symptoms can already be identified during early, prodromal stages of disease. Recent studies provide evidence that during this early prodromal phase, synaptic and axonal abnormalities occur before the degenerative loss of neuronal cell bodies. These early phenotypes can be attributed to synaptic accumulation of toxic α-Syn. Under physiological conditions, α-Syn functions in its native conformation as a soluble monomer. However, PD patient brains are characterized by intracellular inclusions of insoluble fibrils. Yet, oligomers and protofibrils of α-Syn have been identified to be the most toxic species, with their accumulation at presynaptic terminals affecting several steps of neurotransmitter release. First, high levels of α-Syn alter the size of synaptic vesicle pools and impair their trafficking. Second, α-Syn overexpression can either misregulate or redistribute proteins of the presynaptic SNARE complex. This leads to deficient tethering, docking, priming and fusion of synaptic vesicles at the active zone (AZ). Third, α-Syn inclusions are found within the presynaptic AZ, accompanied by a decrease in AZ protein levels. Furthermore, α-Syn overexpression reduces the endocytic retrieval of synaptic vesicle membranes during vesicle recycling. These presynaptic alterations mediated by accumulation of α-Syn, together impair neurotransmitter exocytosis and neuronal communication. Although α-Syn is expressed throughout the brain and enriched at presynaptic terminals, DA neurons are the most vulnerable in PD, likely because α-Syn directly regulates dopamine levels. Indeed, evidence suggests that α-Syn is a negative modulator of dopamine by inhibiting enzymes responsible for its synthesis. In addition,

  14. Synaptic Regulator α-Synuclein in Dopaminergic Fibers Is Essentially Required for the Maintenance of Subependymal Neural Stem Cells.

    PubMed

    Perez-Villalba, Ana; Sirerol-Piquer, M Salomé; Belenguer, Germán; Soriano-Cantón, Raúl; Muñoz-Manchado, Ana Belén; Villadiego, Javier; Alarcón-Arís, Diana; Soria, Federico N; Dehay, Benjamin; Bezard, Erwan; Vila, Miquel; Bortolozzi, Analía; Toledo-Aral, Juan José; Pérez-Sánchez, Francisco; Fariñas, Isabel

    2018-01-24

    Synaptic protein α-synuclein (α-SYN) modulates neurotransmission in a complex and poorly understood manner and aggregates in the cytoplasm of degenerating neurons in Parkinson's disease. Here, we report that α-SYN present in dopaminergic nigral afferents is essential for the normal cycling and maintenance of neural stem cells (NSCs) in the brain subependymal zone of adult male and female mice. We also show that premature senescence of adult NSCs into non-neurogenic astrocytes in mice lacking α-SYN resembles the effects of dopaminergic fiber degeneration resulting from chronic exposure to 1-methyl-4-phenyl-1,2,3,6-tetra-hydropyridine or intranigral inoculation of aggregated toxic α-SYN. Interestingly, NSC loss in α-SYN-deficient mice can be prevented by viral delivery of human α-SYN into their sustantia nigra or by treatment with l-DOPA, suggesting that α-SYN regulates dopamine availability to NSCs. Our data indicate that α-SYN, present in dopaminergic nerve terminals supplying the subependymal zone, acts as a niche component to sustain the neurogenic potential of adult NSCs and identify α-SYN and DA as potential targets to ameliorate neurogenic defects in the aging and diseased brain. SIGNIFICANCE STATEMENT We report an essential role for the protein α-synuclein present in dopaminergic nigral afferents in the regulation of adult neural stem cell maintenance, identifying the first synaptic regulator with an implication in stem cell niche biology. Although the exact role of α-synuclein in neural transmission is not completely clear, our results indicate that it is required for stemness and the preservation of neurogenic potential in concert with dopamine. Copyright © 2018 the authors 0270-6474/18/380815-12$15.00/0.

  15. Mitochondrial dynamics in Parkinson's disease: a role for α-synuclein?

    PubMed Central

    Pozo Devoto, Victorio M.

    2017-01-01

    ABSTRACT The distinctive pathological hallmarks of Parkinson's disease are the progressive death of dopaminergic neurons and the intracellular accumulation of Lewy bodies enriched in α-synuclein protein. Several lines of evidence from the study of sporadic, familial and pharmacologically induced forms of human Parkinson's disease also suggest that mitochondrial dysfunction plays an important role in disease progression. Although many functions have been proposed for α-synuclein, emerging data from human and animal models of Parkinson's disease highlight a role for α-synuclein in the control of neuronal mitochondrial dynamics. Here, we review the α-synuclein structural, biophysical and biochemical properties that influence relevant mitochondrial dynamic processes such as fusion-fission, transport and clearance. Drawing on current evidence, we propose that α-synuclein contributes to the mitochondrial defects that are associated with the pathology of this common and progressive neurodegenerative disease. PMID:28883016

  16. Structural and functional properties of prefibrillar α-synuclein oligomers.

    PubMed

    Pieri, Laura; Madiona, Karine; Melki, Ronald

    2016-04-14

    The deposition of fibrillar alpha-synuclein (α-syn) within inclusions (Lewy bodies and Lewy neurites) in neurons and glial cells is a hallmark of synucleinopathies. α-syn populates a variety of assemblies ranging from prefibrillar oligomeric species to fibrils whose specific contribution to neurodegeneration is still unclear. Here, we compare the specific structural and biological properties of distinct soluble prefibrillar α-syn oligomers formed either spontaneously or in the presence of dopamine and glutaraldehyde. We show that both on-fibrillar assembly pathway and distinct dopamine-mediated and glutaraldehyde-cross-linked α-syn oligomers are only slightly effective in perturbing cell membrane integrity and inducing cytotoxicity, while mature fibrils exhibit the highest toxicity. In contrast to low-molecular weight and unstable oligomers, large stable α-syn oligomers seed the aggregation of soluble α-syn within reporter cells although to a lesser extent than mature α-syn fibrils. These oligomers appear elongated in shape. Our findings suggest that α-syn oligomers represent a continuum of species ranging from unstable low molecular weight particles to mature fibrils via stable elongated oligomers composed of more than 15 α-syn monomers that possess seeding capacity.

  17. Structural and functional properties of prefibrillar α-synuclein oligomers

    PubMed Central

    Pieri, Laura; Madiona, Karine; Melki, Ronald

    2016-01-01

    The deposition of fibrillar alpha-synuclein (α-syn) within inclusions (Lewy bodies and Lewy neurites) in neurons and glial cells is a hallmark of synucleinopathies. α-syn populates a variety of assemblies ranging from prefibrillar oligomeric species to fibrils whose specific contribution to neurodegeneration is still unclear. Here, we compare the specific structural and biological properties of distinct soluble prefibrillar α-syn oligomers formed either spontaneously or in the presence of dopamine and glutaraldehyde. We show that both on-fibrillar assembly pathway and distinct dopamine-mediated and glutaraldehyde-cross-linked α-syn oligomers are only slightly effective in perturbing cell membrane integrity and inducing cytotoxicity, while mature fibrils exhibit the highest toxicity. In contrast to low-molecular weight and unstable oligomers, large stable α-syn oligomers seed the aggregation of soluble α-syn within reporter cells although to a lesser extent than mature α-syn fibrils. These oligomers appear elongated in shape. Our findings suggest that α-syn oligomers represent a continuum of species ranging from unstable low molecular weight particles to mature fibrils via stable elongated oligomers composed of more than 15 α-syn monomers that possess seeding capacity. PMID:27075649

  18. α-Synuclein in Parkinson's Disease

    PubMed Central

    Stefanis, Leonidas

    2012-01-01

    α-Synuclein is a presynaptic neuronal protein that is linked genetically and neuropathologically to Parkinson's disease (PD). α-Synuclein may contribute to PD pathogenesis in a number of ways, but it is generally thought that its aberrant soluble oligomeric conformations, termed protofibrils, are the toxic species that mediate disruption of cellular homeostasis and neuronal death, through effects on various intracellular targets, including synaptic function. Furthermore, secreted α-synuclein may exert deleterious effects on neighboring cells, including seeding of aggregation, thus possibly contributing to disease propagation. Although the extent to which α-synuclein is involved in all cases of PD is not clear, targeting the toxic functions conferred by this protein when it is dysregulated may lead to novel therapeutic strategies not only in PD, but also in other neurodegenerative conditions, termed synucleinopathies. PMID:22355802

  19. Dopamine-dependent neurodegeneration in Drosophila models of familial and sporadic Parkinson's disease.

    PubMed

    Bayersdorfer, Florian; Voigt, Aaron; Schneuwly, Stephan; Botella, José A

    2010-10-01

    Parkinson's disease has been found to be caused by both, genetic and environmental factors. Despite the diversity of causes involved, a convergent pathogenic mechanism might underlie the special vulnerability of dopaminergic neurons in different forms of Parkinsonism. In recent years, a number of reports have proposed dopamine as a common player responsible in the loss of dopaminergic neurons independent of its etiology. Using RNAi lines we were able to generate flies with drastically reduced dopamine levels in the dopaminergic neurons. Combining these flies with a chemically induced Parkinson model (rotenone) and a familial form of Parkinson (mutant alpha-synuclein) we were able to show a strong reduction of neurotoxicity and a protection of the dopaminergic neurons when cellular dopamine levels were reduced. These results show that dopamine homeostasis plays a central role for the susceptibility of dopaminergic neurons to environmental and genetic factors in in vivo models of Parkinson disease. (c) 2010 Elsevier Inc. All rights reserved.

  20. Synthetic Proteins and Peptides for the Direct Interrogation of α-Synuclein Posttranslational Modifications

    PubMed Central

    Pratt, Matthew R.; Abeywardana, Tharindumala; Marotta, Nicholas P.

    2015-01-01

    α-Synuclein is the aggregation-prone protein associated with Parkinson’s disease (PD) and related neurodegenerative diseases. Complicating both its biological functions and toxic aggregation are a variety of posttranslational modifications. These modifications have the potential to either positively or negatively affect α-synuclein aggregation, raising the possibility that the enzymes that add or remove these modifications could be therapeutic targets in PD. Synthetic protein chemistry is uniquely positioned to generate site-specifically and homogeneously modified proteins for biochemical study. Here, we review the application of synthetic peptides and proteins towards understanding the effects of α-synuclein posttranslational modifications. PMID:26120904

  1. Mitochondrial dynamics in Parkinson's disease: a role for α-synuclein?

    PubMed

    Pozo Devoto, Victorio M; Falzone, Tomas L

    2017-09-01

    The distinctive pathological hallmarks of Parkinson's disease are the progressive death of dopaminergic neurons and the intracellular accumulation of Lewy bodies enriched in α-synuclein protein. Several lines of evidence from the study of sporadic, familial and pharmacologically induced forms of human Parkinson's disease also suggest that mitochondrial dysfunction plays an important role in disease progression. Although many functions have been proposed for α-synuclein, emerging data from human and animal models of Parkinson's disease highlight a role for α-synuclein in the control of neuronal mitochondrial dynamics. Here, we review the α-synuclein structural, biophysical and biochemical properties that influence relevant mitochondrial dynamic processes such as fusion-fission, transport and clearance. Drawing on current evidence, we propose that α-synuclein contributes to the mitochondrial defects that are associated with the pathology of this common and progressive neurodegenerative disease. © 2017. Published by The Company of Biologists Ltd.

  2. Dieldrin exposure induces oxidative damage in the mouse nigrostriatal dopamine system

    PubMed Central

    Hatcher, Jaime M.; Richardson, Jason R.; Guillot, Thomas S.; McCormack, Alison L.; Di Monte, Donato A.; Jones, Dean P.; Pennell, Kurt D.; Miller, Gary W.

    2007-01-01

    Numerous epidemiological studies have shown an association between pesticide exposure and an increased risk of developing Parkinson’s disease (PD). Here, we provide evidence that the insecticide dieldrin causes specific oxidative damage in the nigrostriatal dopamine (DA) system. We report that exposure of mice to low levels of dieldrin for 30 days resulted in alterations in dopamine-handling as evidenced by a decrease in dopamine metabolites, DOPAC (31.7% decrease) and HVA (29.2% decrease) and significantly increased cysteinyl-catechol levels in the striatum. Furthermore, dieldrin resulted in a 53% decrease in total glutathione, an increase in the redox potential of glutathione, and a 90% increase in protein carbonyls. α-Synuclein protein expression was also significantly increased in the striatum (25% increase). Finally, dieldrin caused a significant decrease in striatal expression of the dopamine transporter as measured by 3H-WIN 35,428 binding and 3H-dopamine uptake. These alterations occurred in the absence of dopamine neuron loss in the substantia nigra pars compacta. These effects represent the ability of low doses of dieldrin to increase the vulnerability of nigrostriatal dopamine neurons by inducing oxidative stress and suggest that pesticide exposure may act as a promoter of PD. PMID:17291500

  3. Structural Effects of Two Camelid Nanobodies Directed to Distinct C-Terminal Epitopes on α-Synuclein.

    PubMed

    El-Turk, Farah; Newby, Francisco N; De Genst, Erwin; Guilliams, Tim; Sprules, Tara; Mittermaier, Anthony; Dobson, Christopher M; Vendruscolo, Michele

    2016-06-07

    α-Synuclein is an intrinsically disordered protein whose aggregation is associated with Parkinson's disease and other related neurodegenerative disorders. Recently, two single-domain camelid antibodies (nanobodies) were shown to bind α-synuclein with high affinity. Herein, we investigated how these two nanobodies (NbSyn2 and NbSyn87), which are directed to two distinct epitopes within the C-terminal domain of α-synuclein, affect the conformational properties of this protein. Our results suggest that nanobody NbSyn2, which binds to the five C-terminal residues of α-synuclein (residues 136-140), does not disrupt the transient long-range interactions that generate a degree of compaction within the native structural ensemble of α-synuclein. In contrast, the data that we report indicate that NbSyn87, which targets a central region within the C-terminal domain (residues 118-128), has more substantial effects on the fluctuating secondary and tertiary structure of the protein. These results are consistent with the different effects that the two nanobodies have on the aggregation behavior of α-synuclein in vitro. Our findings thus provide new insights into the type of effects that nanobodies can have on the conformational ensemble of α-synuclein.

  4. Consequences of Variations in Genes that affect Dopamine in Prefrontal Cortex

    PubMed Central

    Diamond, Adele

    2008-01-01

    Patricia Goldman-Rakic played a groundbreaking role in investigating the cognitive functions subserved by dorsolateral prefrontal cortex and the key role of dopamine in that. The work discussed here builds on that including: 1) Studies of children predicted to have lower levels of prefrontal dopamine but otherwise basically normal brains (children treated for phenylketonuria [PKU]). Those studies changed medical guidelines, improving the children’s lives. 2) Studies of visual impairments (in contrast sensitivity and motion perception) in PKU children due to reduced retinal dopamine and due to excessive phenylalanine during the first postnatal weeks. Those studies, too, changed medical guidelines. 3) Studies of working memory and inhibitory control differences in typically developing children due to differences in catechol-O-methyltransferase (COMT) genotype, which selectively affect prefrontal dopamine levels. 4) Studies of gender differences in the effect of COMT genotype on cognitive performance in older adults. 5) A hypothesis about fundamental differences between attention deficit hyperactivity disorder (ADHD) that includes hyperactivity and ADHD of the inattentive type. Those disorders are hypothesized to differ in the affected neural system, underlying genetics, responsiveness to medication, comorbidities, and cognitive and behavioral profiles. These sound quite disparate but they all grew systematically out the base laid down by Patricia Goldman-Rakic. PMID:17725999

  5. Recent advances in α-synuclein functions, advanced glycation, and toxicity: implications for Parkinson's disease.

    PubMed

    Guerrero, Erika; Vasudevaraju, P; Hegde, Muralidhar L; Britton, G B; Rao, K S

    2013-04-01

    The toxicity of α-synuclein in the neuropathology of Parkinson's disease which includes its hallmark aggregation has been studied scrupulously in the last decade. Although little is known regarding the normal functions of α-synuclein, its association with membrane phospholipids suggests its potential role in signaling pathways. Following extensive evidences for its nuclear localization, we and others recently demonstrated DNA binding activity of α-synuclein that modulates its conformation as well as aggregation properties. Furthermore, we also underscored the similarities among various amyloidogenic proteins involved in neurodegenerative diseases including amyloid beta peptides and tau. Our more recent studies show that α-synuclein is glycated and glycosylated both in vitro and in neurons, significantly affecting its folding, oligomeric, and DNA binding properties. Glycated α-synuclein causes increased genome damage both via its direct interaction with DNA and by increased generation of reactive oxygen species as glycation byproduct. In this review, we discuss the mechanisms of glycation and other posttranslational modifications of α-synuclein, including phosphorylation and nitration, and their role in neuronal death in Parkinson's disease.

  6. Deletion of alpha-synuclein decreases impulsivity in mice.

    PubMed

    Peña-Oliver, Y; Buchman, V L; Dalley, J W; Robbins, T W; Schumann, G; Ripley, T L; King, S L; Stephens, D N

    2012-03-01

    The presynaptic protein alpha-synuclein, associated with Parkinson's Disease (PD), plays a role in dopaminergic neurotransmission and is implicated in impulse control disorders (ICDs) such as drug addiction. In this study we investigated a potential causal relationship between alpha-synuclein and impulsivity, by evaluating differences in motor impulsivity in the 5-choice serial reaction time task (5-CSRTT) in strains of mice that differ in the expression of the alpha-synuclein gene. C57BL/6JOlaHsd mice differ from their C57BL/6J ancestors in possessing a chromosomal deletion resulting in the loss of two genes, snca, encoding alpha-synuclein, and mmrn1, encoding multimerin-1. C57BL/6J mice displayed higher impulsivity (more premature responding) than C57BL/6JOlaHsd mice when the pre-stimulus waiting interval was increased in the 5-CSRTT. In order to ensure that the reduced impulsivity was indeed related to snca, and not adjacent gene deletion, wild type (WT) and mice with targeted deletion of alpha-synuclein (KO) were tested in the 5-CSRTT. Similarly, WT mice were more impulsive than mice with targeted deletion of alpha-synuclein. Interrogation of our ongoing analysis of impulsivity in BXD recombinant inbred mouse lines revealed an association of impulsive responding with levels of alpha-synuclein expression in hippocampus. Expression of beta- and gamma-synuclein, members of the synuclein family that may substitute for alpha-synuclein following its deletion, revealed no differential compensations among the mouse strains. These findings suggest that alpha-synuclein may contribute to impulsivity and potentially, to ICDs which arise in some PD patients treated with dopaminergic medication. © 2011 The Authors. Genes, Brain and Behavior © 2011 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society.

  7. Serotonin and dopamine differentially affect appetitive and aversive general Pavlovian-to-instrumental transfer.

    PubMed

    Hebart, Martin N; Gläscher, Jan

    2015-01-01

    Human motivation and decision-making is influenced by the interaction of Pavlovian and instrumental systems. The neurotransmitters dopamine and serotonin have been suggested to play a major role in motivation and decision-making, but how they affect this interaction in humans is largely unknown. We investigated the effect of these neurotransmitters in a general Pavlovian-to-instrumental transfer (PIT) task which measured the nonspecific effect of appetitive and aversive Pavlovian cues on instrumental responses. For that purpose, we used selective dietary depletion of the amino acid precursors of serotonin and dopamine: tryptophan (n = 34) and tyrosine/phenylalanine (n = 35), respectively, and compared the performance of these groups to a control group (n = 34) receiving a nondepleted (balanced) amino acid drink. We found that PIT differed between groups: Relative to the control group that exhibited only appetitive PIT, we found reduced appetitive PIT in the tyrosine/phenylalanine-depleted group and enhanced aversive PIT in the tryptophan-depleted group. These results demonstrate a differential involvement of serotonin and dopamine in motivated behavior. They suggest that reductions in serotonin enhance the motivational influence of aversive stimuli on instrumental behavior and do not affect the influence of appetitive stimuli, while reductions in dopamine diminish the influence of appetitive stimuli. No conclusions could be drawn about how dopamine affects the influence of aversive stimuli. The interplay of both neurotransmitter systems allows for flexible and adaptive responses depending on the behavioral context.

  8. FYCO1 mediates clearance of α-synuclein aggregates through a Rab7-dependent mechanism.

    PubMed

    Saridaki, Theodora; Nippold, Markus; Dinter, Elisabeth; Roos, Andreas; Diederichs, Leonie; Fensky, Luisa; Schulz, Jörg B; Falkenburger, Björn H

    2018-05-10

    Parkinson disease can be caused by mutations in the α-synuclein gene and is characterized by aggregates of α-synuclein protein. We have previously shown that overexpression of the small GTPase Rab7 can induce clearance of α-synuclein aggregates. In this study, we investigate which Rab7 effectors mediate this effect. To model Parkinson disease we expressed the pathogenic A53T mutant of α-synuclein in HEK293T cells and Drosophila melanogaster. We tested the Rab7 effectors FYVE and coiled-coil domain-containing protein 1 (FYCO1) and Rab-interacting lysosomal protein (RILP). FYCO1-EGFP decorated vesicles containing α-synuclein. RILP-EGFP also decorated vesicular structures, but they did not contain α-synuclein. FYCO1 overexpression reduced the number of cells with α-synuclein aggregates, defined as visible particles of EGFP-tagged α-synuclein, whereas RILP did not. FYCO1 but not RILP reduced the amount of α-synuclein protein as assayed by western blot, increased the disappearance of α-synuclein aggregates in time-lapse microscopy, and decreased α-synuclein-induced toxicity assayed by the Trypan blue assay. siRNA-mediated knockdown of FYCO1 but not RILP reduced Rab7 induced aggregate clearance. Collectively, these findings indicate that FYCO1 and not RILP mediates Rab7 induced aggregate clearance. The effect of FYCO1 on aggregate clearance was blocked by the dominant negative Rab7 indicating that FYCO1 requires active Rab7 to function. Electron microscopic analysis and insertion of lysosomal membranes into the plasma membrane indicate that FYCO1 could lead to secretion of α-synuclein aggregates. Extracellular α-synuclein as assayed by ELISA was, however, not increased with FYCO1. Coexpression of FYCO1 in the fly model decreased α-synuclein aggregates as shown by the filter trap assay and rescued the locomotor deficit resulting from neuronal A53T-α-synuclein expression. This latter finding confirms that a pathway involving Rab7 and FYCO1 stimulates

  9. Human β-Synuclein Rendered Fibrillogenic by Designed Mutations

    PubMed Central

    Zibaee, Shahin; Fraser, Graham; Jakes, Ross; Owen, David; Serpell, Louise C.; Crowther, R. Anthony; Goedert, Michel

    2010-01-01

    Filamentous inclusions made of α-synuclein are found in nerve cells and glial cells in a number of human neurodegenerative diseases, including Parkinson disease, dementia with Lewy bodies, and multiple system atrophy. The assembly and spreading of these inclusions are likely to play an important role in the etiology of common dementias and movement disorders. Both α-synuclein and the homologous β-synuclein are abundantly expressed in the central nervous system; however, β-synuclein is not present in the pathological inclusions. Previously, we observed a poor correlation between filament formation and the presence of residues 73–83 of α-synuclein, which are absent in β-synuclein. Instead, filament formation correlated with the mean β-sheet propensity, charge, and hydrophilicity of the protein (global physicochemical properties) and β-strand contiguity calculated by a simple algorithm of sliding averages (local physicochemical property). In the present study, we rendered β-synuclein fibrillogenic via one set of point mutations engineered to enhance global properties and a second set engineered to enhance predominantly β-strand contiguity. Our findings show that the intrinsic physicochemical properties of synucleins influence their fibrillogenic propensity via two distinct but overlapping modalities. The implications for filament formation and the pathogenesis of neurodegenerative diseases are discussed. PMID:20833719

  10. Advancing Stem Cell Models of Alpha-Synuclein Gene Regulation in Neurodegenerative Disease.

    PubMed

    Piper, Desiree A; Sastre, Danuta; Schüle, Birgitt

    2018-01-01

    Alpha-synuclein ( non A4 component of amyloid precursor, SNCA, NM_000345.3 ) plays a central role in the pathogenesis of Parkinson's disease (PD) and related Lewy body disorders such as Parkinson's disease dementia, Lewy body dementia, and multiple system atrophy. Since its discovery as a disease-causing gene in 1997, alpha-synuclein has been a central point of scientific interest both at the protein and gene level. Mutations, including copy number variants, missense mutations, short structural variants, and single nucleotide polymorphisms, can be causative for PD and affect conformational changes of the protein, can contribute to changes in expression of alpha-synuclein and its isoforms, and can influence regulation of temporal as well as spatial levels of alpha-synuclein in different tissues and cell types. A lot of progress has been made to understand both the physiological transcriptional and epigenetic regulation of the alpha-synuclein gene and whether changes in transcriptional regulation could lead to disease and neurodegeneration in PD and related alpha-synucleinopathies. Although the histopathological changes in these neurodegenerative disorders are similar, the temporal and spatial presentation and progression distinguishes them which could be in part due to changes or disruption of transcriptional regulation of alpha-synuclein. In this review, we describe different genetic alterations that contribute to PD and neurodegenerative conditions and review aspects of transcriptional regulation of the alpha-synuclein gene in the context of the development of PD. New technologies, advanced gene engineering and stem cell modeling, are on the horizon to shed further light on a better understanding of gene regulatory processes and exploit them for therapeutic developments.

  11. A de novo compound targeting α-synuclein improves deficits in models of Parkinson’s disease

    PubMed Central

    Wrasidlo, Wolfgang; Tsigelny, Igor F.; Price, Diana L.; Dutta, Garima; Rockenstein, Edward; Schwarz, Thomas C.; Ledolter, Karin; Bonhaus, Douglas; Paulino, Amy; Eleuteri, Simona; Skjevik, Åge A.; Kouznetsova, Valentina L.; Spencer, Brian; Desplats, Paula; Gonzalez-Ruelas, Tania; Trejo-Morales, Margarita; Overk, Cassia R.; Winter, Stefan; Zhu, Chunni; Chesselet, Marie-Francoise; Meier, Dieter; Moessler, Herbert; Konrat, Robert; Masliah, Eliezer

    2016-01-01

    Abnormal accumulation and propagation of the neuronal protein α-synuclein has been hypothesized to underlie the pathogenesis of Parkinson’s disease, dementia with Lewy bodies and multiple system atrophy. Here we report a de novo-developed compound (NPT100-18A) that reduces α-synuclein toxicity through a novel mechanism that involves displacing α-synuclein from the membrane. This compound interacts with a domain in the C-terminus of α-synuclein. The E83R mutation reduces the compound interaction with the 80–90 amino acid region of α-synuclein and prevents the effects of NPT100-18A. In vitro studies showed that NPT100-18A reduced the formation of wild-type α-synuclein oligomers in membranes, reduced the neuronal accumulation of α-synuclein, and decreased markers of cell toxicity. In vivo studies were conducted in three different α-synuclein transgenic rodent models. Treatment with NPT100-18A ameliorated motor deficits in mThy1 wild-type α-synuclein transgenic mice in a dose-dependent manner at two independent institutions. Neuropathological examination showed that NPT100-18A decreased the accumulation of proteinase K-resistant α-synuclein aggregates in the CNS and was accompanied by the normalization of neuronal and inflammatory markers. These results were confirmed in a mutant line of α-synuclein transgenic mice that is prone to generate oligomers. In vivo imaging studies of α-synuclein-GFP transgenic mice using two-photon microscopy showed that NPT100-18A reduced the cortical synaptic accumulation of α-synuclein within 1 h post-administration. Taken together, these studies support the notion that altering the interaction of α-synuclein with the membrane might be a feasible therapeutic approach for developing new disease-modifying treatments of Parkinson’s disease and other synucleinopathies. PMID:27679481

  12. Clearing Extracellular Alpha-Synuclein from Cerebrospinal Fluid: A New Therapeutic Strategy in Parkinson's Disease.

    PubMed

    Menéndez-González, Manuel; Padilla-Zambrano, Huber S; Tomás-Zapico, Cristina; García, Benjamin Fernández

    2018-03-23

    This concept article aims to show the rationale of targeting extracellular α-Synuclein (α-Syn) from cerebrospinal fluid (CSF) as a new strategy to remove this protein from the brain in Parkinson's disease (PD). Misfolding and intracellular aggregation of α-synuclein into Lewy bodies are thought to be crucial in the pathogenesis of PD. Recent research has shown that small amounts of monomeric and oligomeric α-synuclein are released from neuronal cells by exocytosis and that this extracellular alpha-synuclein contributes to neurodegeneration, progressive spreading of alpha-synuclein pathology, and neuroinflammation. In PD, extracellular oligomeric-α-synuclein moves in constant equilibrium between the interstitial fluid (ISF) and the CSF. Thus, we expect that continuous depletion of oligomeric-α-synuclein in the CSF will produce a steady clearance of the protein in the ISF, preventing transmission and deposition in the brain.

  13. Rotenone Upregulates Alpha-Synuclein and Myocyte Enhancer Factor 2D Independently from Lysosomal Degradation Inhibition

    PubMed Central

    Stefanoni, Giovanni; Melchionda, Laura; Riva, Chiara; Brighina, Laura

    2013-01-01

    Dysfunctions of chaperone-mediated autophagy (CMA), the main catabolic pathway for alpha-synuclein, have been linked to the pathogenesis of Parkinson's disease (PD). Since till now there is limited information on how PD-related toxins may affect CMA, in this study we explored the effect of mitochondrial complex I inhibitor rotenone on CMA substrates, alpha-synuclein and MEF2D, and effectors, lamp2A and hsc70, in a human dopaminergic neuroblastoma SH-SY5Y cell line. Rotenone induced an upregulation of alpha-synuclein and MEF2D protein levels through the stimulation of their de novo synthesis rather than through a reduction of their CMA-mediated degradation. Moreover, increased MEF2D transcription resulted in higher nuclear protein levels that exert a protective role against mitochondrial dysfunction and oxidative stress. These results were compared with those obtained after lysosome inhibition with ammonium chloride. As expected, this toxin induced the cytosolic accumulation of both alpha-synuclein and MEF2D proteins, as the result of the inhibition of their lysosome-mediated degradation, while, differently from rotenone, ammonium chloride decreased MEF2D nuclear levels through the downregulation of its transcription, thus reducing its protective function. These results highlight that rotenone affects alpha-synuclein and MEF2D protein levels through a mechanism independent from lysosomal degradation inhibition. PMID:23984410

  14. Potential Modes of Intercellular α-Synuclein Transmission

    PubMed Central

    Valdinocci, Dario; Radford, Rowan A. W.; Siow, Sue Maye; Chung, Roger S.; Pountney, Dean L.

    2017-01-01

    Intracellular aggregates of the α-synuclein protein result in cell loss and dysfunction in Parkinson’s disease and atypical Parkinsonism, such as multiple system atrophy and dementia with Lewy bodies. Each of these neurodegenerative conditions, known collectively as α-synucleinopathies, may be characterized by a different suite of molecular triggers that initiate pathogenesis. The mechanisms whereby α-synuclein aggregates mediate cytotoxicity also remain to be fully elucidated. However, recent studies have implicated the cell-to-cell spread of α-synuclein as the major mode of disease propagation between brain regions during disease progression. Here, we review the current evidence for different modes of α-synuclein cellular release, movement and uptake, including exocytosis, exosomes, tunneling nanotubes, glymphatic flow and endocytosis. A more detailed understanding of the major modes by which α-synuclein pathology spreads throughout the brain may provide new targets for therapies that halt the progression of disease. PMID:28241427

  15. Potential Modes of Intercellular α-Synuclein Transmission.

    PubMed

    Valdinocci, Dario; Radford, Rowan A W; Siow, Sue Maye; Chung, Roger S; Pountney, Dean L

    2017-02-22

    Intracellular aggregates of the α-synuclein protein result in cell loss and dysfunction in Parkinson's disease and atypical Parkinsonism, such as multiple system atrophy and dementia with Lewy bodies. Each of these neurodegenerative conditions, known collectively as α-synucleinopathies, may be characterized by a different suite of molecular triggers that initiate pathogenesis. The mechanisms whereby α-synuclein aggregates mediate cytotoxicity also remain to be fully elucidated. However, recent studies have implicated the cell-to-cell spread of α-synuclein as the major mode of disease propagation between brain regions during disease progression. Here, we review the current evidence for different modes of α-synuclein cellular release, movement and uptake, including exocytosis, exosomes, tunneling nanotubes, glymphatic flow and endocytosis. A more detailed understanding of the major modes by which α-synuclein pathology spreads throughout the brain may provide new targets for therapies that halt the progression of disease.

  16. Agrochemicals, α-synuclein, and Parkinson's disease.

    PubMed

    Silva, Blanca A; Breydo, Leonid; Fink, Anthony L; Uversky, Vladimir N

    2013-04-01

    Epidemiological, population-based case-control, and experimental studies at the molecular, cellular, and organism levels revealed that exposure to various environmental agents, including a number of structurally different agrochemicals, may contribute to the pathogenesis of Parkinson's disease (PD) and several other neurodegenerative disorders. The role of genetic predisposition in PD has also been increasingly acknowledged, driven by the identification of a number of disease-related genes [e.g., α-synuclein, parkin, DJ-1, ubiquitin C-terminal hydrolase isozyme L1 (UCH-L1), and nuclear receptor-related factor 1]. Therefore, the etiology of this multifactorial disease is likely to involve both genetic and environmental factors. Various neurotoxicants, including agrochemicals, have been shown to elevate the levels of α-synuclein expression in neurons and to promote aggregation of this protein in vivo. Many agrochemicals physically interact with α-synuclein and accelerate the fibrillation and aggregation rates of this protein in vitro. This review analyzes some of the aspects linking α-synuclein to PD, provides brief structural and functional descriptions of this important protein, and represents some data connecting exposure to agrochemicals with α-synuclein aggregation and PD pathogenesis.

  17. The Identification of Alpha-Synuclein as the First Parkinson Disease Gene.

    PubMed

    Nussbaum, Robert L

    2017-01-01

    In this Commentary, I describe the events that led from an NINDS-sponsored Workshop on Parkinson Disease Research in 1995, where I was asked to speak about the genetics of Parkinson disease, to the identification a mere two years later of a mutation in alpha-synuclein as the cause of autosomal dominant Parkinson disease in the Contursi kindred. I review the steps we took to first map and then find the mutation in the alpha-synuclein locus and describe the obstacles and the role of serendipity in facilitating the work. Although alpha-synuclein mutations are a rare cause of hereditary PD, the importance of this finding goes far beyond the rare families with hereditary disease because it pinpointed alpha-synuclein as a key contributor to the far more common sporadic form of Parkinson disease. This work confirms William Harvey's observation from 350 years ago that studying rarer forms of a disease is an excellent way to understand the more common forms of that disease. The identification of synuclein's role in hereditary Parkinson disease has opened new avenues of research into the pathogenesis and potential treatments of the common form of Parkinson disease that affects many millions of Americans and tens of millions of human beings worldwide.

  18. Long-term dopamine transporter expression and normal cellular distribution of mitochondria in dopaminergic neuron transplants in Parkinson’s disease patients

    PubMed Central

    Hallett, Penelope J; Cooper, Oliver; Sadi, Damaso; Robertson, Harold; Mendez, Ivar; Isacson, Ole

    2014-01-01

    Summary To determine the long-term health and function of transplanted dopamine neurons in Parkinson’s disease (PD) patients, the expression of dopamine transporters (DAT) and mitochondrial morphology was examined in human fetal midbrain cellular transplants. DAT was robustly expressed in transplanted dopamine neuron terminals in the reinnervated host putamen and caudate, for at least 14 years after transplantation. The transplanted dopamine neurons showed a healthy and non-atrophied morphology at all time points. Labeling of the mitochondrial outer membrane protein Tom20 and alpha-synuclein showed typical cellular pathology in the patients’ own substantia nigra, which was not observed in transplanted dopamine neurons. These results show that the vast majority of transplanted neurons remain healthy long-term in PD patients, consistent with the clinically maintained function of fetal dopamine neuron transplants for up to 15–18 years in patients. These findings are critically important for the rational development of stem cell-based dopamine neuronal replacement therapies for PD. PMID:24910427

  19. Immunotherapy targeting α-synuclein, with relevance for future treatment of Parkinson's disease and other Lewy body disorders.

    PubMed

    Lindström, Veronica; Ihse, Elisabet; Fagerqvist, Therese; Bergström, Joakim; Nordström, Eva; Möller, Christer; Lannfelt, Lars; Ingelsson, Martin

    2014-01-01

    Immunotherapy targeting α-synuclein has evolved as a potential therapeutic strategy for neurodegenerative diseases, such as Parkinson's disease, and initial studies on cellular and animal models have shown promising results. α-synuclein vaccination of transgenic mice reduced the number of brain inclusions, whereas passive immunization studies demonstrated that antibodies against the C-terminus of α-synuclein can pass the blood-brain barrier and affect the pathology. In addition, preliminary evidence suggests that transgenic mice treated with an antibody directed against α-synuclein oligomers/protofibrils resulted in reduced levels of such species in the CNS. The underlying mechanisms of immunotherapy are not yet fully understood, but may include antibody-mediated clearance of pre-existing aggregates, prevention of protein propagation between cells and microglia-dependent protein clearance. Thus, immunotherapy targeting α-synuclein holds promise, but needs to be further developed as a future disease-modifying treatment in Parkinson's disease and other α-synucleinopathies.

  20. Transient β-hairpin formation in α-synuclein monomer revealed by coarse-grained molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Yu, Hang; Han, Wei; Ma, Wen; Schulten, Klaus

    2015-12-01

    Parkinson's disease, originating from the intrinsically disordered peptide α-synuclein, is a common neurodegenerative disorder that affects more than 5% of the population above age 85. It remains unclear how α-synuclein monomers undergo conformational changes leading to aggregation and formation of fibrils characteristic for the disease. In the present study, we perform molecular dynamics simulations (over 180 μs in aggregated time) using a hybrid-resolution model, Proteins with Atomic details in Coarse-grained Environment (PACE), to characterize in atomic detail structural ensembles of wild type and mutant monomeric α-synuclein in aqueous solution. The simulations reproduce structural properties of α-synuclein characterized in experiments, such as secondary structure content, long-range contacts, chemical shifts, and 3J(HNHCα)-coupling constants. Most notably, the simulations reveal that a short fragment encompassing region 38-53, adjacent to the non-amyloid-β component region, exhibits a high probability of forming a β-hairpin; this fragment, when isolated from the remainder of α-synuclein, fluctuates frequently into its β-hairpin conformation. Two disease-prone mutations, namely, A30P and A53T, significantly accelerate the formation of a β-hairpin in the stated fragment. We conclude that the formation of a β-hairpin in region 38-53 is a key event during α-synuclein aggregation. We predict further that the G47V mutation impedes the formation of a turn in the β-hairpin and slows down β-hairpin formation, thereby retarding α-synuclein aggregation.

  1. Clearing Extracellular Alpha-Synuclein from Cerebrospinal Fluid: A New Therapeutic Strategy in Parkinson’s Disease

    PubMed Central

    Padilla-Zambrano, Huber S.; Tomás-Zapico, Cristina; García, Benjamin Fernández

    2018-01-01

    This concept article aims to show the rationale of targeting extracellular α-Synuclein (α-Syn) from cerebrospinal fluid (CSF) as a new strategy to remove this protein from the brain in Parkinson’s disease (PD). Misfolding and intracellular aggregation of α-synuclein into Lewy bodies are thought to be crucial in the pathogenesis of PD. Recent research has shown that small amounts of monomeric and oligomeric α-synuclein are released from neuronal cells by exocytosis and that this extracellular alpha-synuclein contributes to neurodegeneration, progressive spreading of alpha-synuclein pathology, and neuroinflammation. In PD, extracellular oligomeric-α-synuclein moves in constant equilibrium between the interstitial fluid (ISF) and the CSF. Thus, we expect that continuous depletion of oligomeric-α-synuclein in the CSF will produce a steady clearance of the protein in the ISF, preventing transmission and deposition in the brain. PMID:29570693

  2. Structure and properties of a complex of α-synuclein and a single-domain camelid antibody.

    PubMed

    De Genst, Erwin J; Guilliams, Tim; Wellens, Joke; O'Day, Elizabeth M; Waudby, Christopher A; Meehan, Sarah; Dumoulin, Mireille; Hsu, Shang-Te Danny; Cremades, Nunilo; Verschueren, Koen H G; Pardon, Els; Wyns, Lode; Steyaert, Jan; Christodoulou, John; Dobson, Christopher M

    2010-09-17

    The aggregation of the intrinsically disordered protein α-synuclein to form fibrillar amyloid structures is intimately associated with a variety of neurological disorders, most notably Parkinson's disease. The molecular mechanism of α-synuclein aggregation and toxicity is not yet understood in any detail, not least because of the paucity of structural probes through which to study the behavior of such a disordered system. Here, we describe an investigation involving a single-domain camelid antibody, NbSyn2, selected by phage display techniques to bind to α-synuclein, including the exploration of its effects on the in vitro aggregation of the protein under a variety of conditions. We show using isothermal calorimetric methods that NbSyn2 binds specifically to monomeric α-synuclein with nanomolar affinity and by means of NMR spectroscopy that it interacts with the four C-terminal residues of the protein. This latter finding is confirmed by the determination of a crystal structure of NbSyn2 bound to a peptide encompassing the nine C-terminal residues of α-synuclein. The NbSyn2:α-synuclein interaction is mediated mainly by side-chain interactions while water molecules cross-link the main-chain atoms of α-synuclein to atoms of NbSyn2, a feature we believe could be important in intrinsically disordered protein interactions more generally. The aggregation behavior of α-synuclein at physiological pH, including the morphology of the resulting fibrillar structures, is remarkably unaffected by the presence of NbSyn2 and indeed we show that NbSyn2 binds strongly to the aggregated as well as to the soluble forms of α-synuclein. These results give strong support to the conjecture that the C-terminal region of the protein is not directly involved in the mechanism of aggregation and suggest that binding of NbSyn2 could be a useful probe for the identification of α-synuclein aggregation in vitro and possibly in vivo. Copyright © 2010. Published by Elsevier Ltd.

  3. Breathing is affected by dopamine D2-like receptors in the basolateral amygdala.

    PubMed

    Sugita, Toshihisa; Kanamaru, Mitsuko; Iizuka, Makito; Sato, Kanako; Tsukada, Setsuro; Kawamura, Mitsuru; Homma, Ikuo; Izumizaki, Masahiko

    2015-04-01

    The precise mechanisms underlying how emotions change breathing patterns remain unclear, but dopamine is a candidate neurotransmitter in the process of emotion-associated breathing. We investigated whether basal dopamine release occurs in the basolateral amygdala (BLA), where sensory-related inputs are received and lead to fear or anxiety responses, and whether D1- and D2-like receptor antagonists affect breathing patterns and dopamine release in the BLA. Adult male mice (C57BL/6N) were perfused with artificial cerebrospinal fluid, a D1-like receptor antagonist (SCH 23390), or a D2-like receptor antagonist ((S)-(-)-sulpiride) through a microdialysis probe in the BLA. Respiratory variables were measured using a double-chamber plethysmograph. Dopamine release was measured by an HPLC. Perfusion of (S)-(-)-sulpiride in the BLA, not SCH 23390, specifically decreased respiratory rate without changes in local release of dopamine. These results suggest that basal dopamine release in the BLA, at least partially, increases respiratory rates only through post-synaptic D2-like receptors, not autoreceptors, which might be associated with emotional responses. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Accumulation of oligomer-prone α-synuclein exacerbates synaptic and neuronal degeneration in vivo

    PubMed Central

    Rockenstein, Edward; Nuber, Silke; Overk, Cassia R.; Ubhi, Kiren; Mante, Michael; Patrick, Christina; Adame, Anthony; Trejo-Morales, Margarita; Gerez, Juan; Picotti, Paola; Jensen, Poul H.; Campioni, Silvia; Riek, Roland; Winkler, Jürgen; Gage, Fred H.; Winner, Beate

    2014-01-01

    In Parkinson’s disease and dementia with Lewy bodies, α-synuclein aggregates to form oligomers and fibrils; however, the precise nature of the toxic α-synuclein species remains unclear. A number of synthetic α-synuclein mutations were recently created (E57K and E35K) that produce species of α-synuclein that preferentially form oligomers and increase α-synuclein-mediated toxicity. We have shown that acute lentiviral expression of α-synuclein E57K leads to the degeneration of dopaminergic neurons; however, the effects of chronic expression of oligomer-prone α-synuclein in synapses throughout the brain have not been investigated. Such a study could provide insight into the possible mechanism(s) through which accumulation of α-synuclein oligomers in the synapse leads to neurodegeneration. For this purpose, we compared the patterns of neurodegeneration and synaptic damage between a newly generated mThy-1 α-synuclein E57K transgenic mouse model that is prone to forming oligomers and the mThy-1 α-synuclein wild-type mouse model (Line 61), which accumulates various forms of α-synuclein. Three lines of α-synuclein E57K (Lines 9, 16 and 54) were generated and compared with the wild-type. The α-synuclein E57K Lines 9 and 16 were higher expressings of α-synuclein, similar to α-synuclein wild-type Line 61, and Line 54 was a low expressing of α-synuclein compared to Line 61. By immunoblot analysis, the higher-expressing α-synuclein E57K transgenic mice showed abundant oligomeric, but not fibrillar, α-synuclein whereas lower-expressing mice accumulated monomeric α-synuclein. Monomers, oligomers, and fibrils were present in α-synuclein wild-type Line 61. Immunohistochemical and ultrastructural analyses demonstrated that α-synuclein accumulated in the synapses but not in the neuronal cells bodies, which was different from the α-synuclein wild-type Line 61, which accumulates α-synuclein in the soma. Compared to non-transgenic and lower-expressing mice, the

  5. Accumulation of oligomer-prone α-synuclein exacerbates synaptic and neuronal degeneration in vivo.

    PubMed

    Rockenstein, Edward; Nuber, Silke; Overk, Cassia R; Ubhi, Kiren; Mante, Michael; Patrick, Christina; Adame, Anthony; Trejo-Morales, Margarita; Gerez, Juan; Picotti, Paola; Jensen, Poul H; Campioni, Silvia; Riek, Roland; Winkler, Jürgen; Gage, Fred H; Winner, Beate; Masliah, Eliezer

    2014-05-01

    In Parkinson's disease and dementia with Lewy bodies, α-synuclein aggregates to form oligomers and fibrils; however, the precise nature of the toxic α-synuclein species remains unclear. A number of synthetic α-synuclein mutations were recently created (E57K and E35K) that produce species of α-synuclein that preferentially form oligomers and increase α-synuclein-mediated toxicity. We have shown that acute lentiviral expression of α-synuclein E57K leads to the degeneration of dopaminergic neurons; however, the effects of chronic expression of oligomer-prone α-synuclein in synapses throughout the brain have not been investigated. Such a study could provide insight into the possible mechanism(s) through which accumulation of α-synuclein oligomers in the synapse leads to neurodegeneration. For this purpose, we compared the patterns of neurodegeneration and synaptic damage between a newly generated mThy-1 α-synuclein E57K transgenic mouse model that is prone to forming oligomers and the mThy-1 α-synuclein wild-type mouse model (Line 61), which accumulates various forms of α-synuclein. Three lines of α-synuclein E57K (Lines 9, 16 and 54) were generated and compared with the wild-type. The α-synuclein E57K Lines 9 and 16 were higher expressings of α-synuclein, similar to α-synuclein wild-type Line 61, and Line 54 was a low expressing of α-synuclein compared to Line 61. By immunoblot analysis, the higher-expressing α-synuclein E57K transgenic mice showed abundant oligomeric, but not fibrillar, α-synuclein whereas lower-expressing mice accumulated monomeric α-synuclein. Monomers, oligomers, and fibrils were present in α-synuclein wild-type Line 61. Immunohistochemical and ultrastructural analyses demonstrated that α-synuclein accumulated in the synapses but not in the neuronal cells bodies, which was different from the α-synuclein wild-type Line 61, which accumulates α-synuclein in the soma. Compared to non-transgenic and lower-expressing mice, the

  6. Modulation of α-synuclein fibrillization by ring-fused 2-pyridones: templation and inhibition involve oligomers with different structure.

    PubMed

    Horvath, Istvan; Sellstedt, Magnus; Weise, Christoph; Nordvall, Lina-Maria; Krishna Prasad, G; Olofsson, Anders; Larsson, Göran; Almqvist, Fredrik; Wittung-Stafshede, Pernilla

    2013-04-15

    In a recent study we discovered that a ring-fused 2-pyridone compound triggered fibrillization of a key protein in Parkinson's disease, α-synuclein. To reveal how variations in compound structure affect protein aggregation, we now prepared a number of strategic analogs and tested their effects on α-synuclein amyloid fiber formation in vitro. We find that, in contrast to the earlier templating effect, some analogs inhibit α-synuclein fibrillization. For both templating and inhibiting compounds, the key species formed in the reactions are α-synuclein oligomers that contain compound. Despite similar macroscopic appearance, the templating and inhibiting oligomers are distinctly different in secondary structure content. When the inhibitory oligomers are added in seed amounts, they inhibit fresh α-synuclein aggregation reactions. Our study demonstrates that small chemical changes to the same central fragment can result in opposite effects on protein aggregation. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Alpha-synuclein levels in blood plasma decline with healthy aging.

    PubMed

    Koehler, Niklas K U; Stransky, Elke; Meyer, Mirjam; Gaertner, Susanne; Shing, Mona; Schnaidt, Martina; Celej, Maria S; Jovin, Thomas M; Leyhe, Thomas; Laske, Christoph; Batra, Anil; Buchkremer, Gerhard; Fallgatter, Andreas J; Wernet, Dorothee; Richartz-Salzburger, Elke

    2015-01-01

    There is unequivocal evidence that alpha-synuclein plays a pivotal pathophysiological role in neurodegenerative diseases, and in particular in synucleinopathies. These disorders present with a variable extent of cognitive impairment and alpha-synuclein is being explored as a biomarker in CSF, blood serum and plasma. Considering key events of aging that include proteostasis, alpha-synuclein may not only be useful as a marker for differential diagnosis but also for aging per se. To explore this hypothesis, we developed a highly specific ELISA to measure alpha-synuclein. In healthy males plasma alpha-synuclein levels correlated strongly with age, revealing much lower concentrations in older (avg. 58.1 years) compared to younger (avg. 27.6 years) individuals. This difference between the age groups was enhanced after acidification of the plasmas (p<0.0001), possibly reflecting a decrease of alpha-synuclein-antibody complexes or chaperone activity in older individuals. Our results support the concept that alpha-synuclein homeostasis may be impaired early on, possibly due to disturbance of the proteostasis network, a key component of healthy aging. Thus, alpha-synuclein may be a novel biomarker of aging, a factor that should be considered when analyzing its presence in biological specimens.

  8. Alpha-synuclein, epigenetics, mitochondria, metabolism, calcium traffic, & circadian dysfunction in Parkinson's disease. An integrated strategy for management.

    PubMed

    Phillipson, Oliver T

    2017-11-01

    The motor deficits which characterise the sporadic form of Parkinson's disease arise from age-related loss of a subset of dopamine neurons in the substantia nigra. Although motor symptoms respond to dopamine replacement therapies, the underlying disease process remains. This review details some features of the progressive molecular pathology and proposes deployment of a combination of nutrients: R-lipoic acid, acetyl-l-carnitine, ubiquinol, melatonin (or receptor agonists) and vitamin D3, with the collective potential to slow progression of these features. The main nutrient targets include impaired mitochondria and the associated oxidative/nitrosative stress, calcium stress and impaired gene transcription induced by pathogenic forms of alpha- synuclein. Benefits may be achieved via nutrient influence on epigenetic signaling pathways governing transcription factors for mitochondrial biogenesis, antioxidant defences and the autophagy-lysosomal pathway, via regulation of the metabolic energy sensor AMP activated protein kinase (AMPK) and the mammalian target of rapamycin mTOR. Nutrients also benefit expression of the transcription factor for neuronal survival (NR4A2), trophic factors GDNF and BDNF, and age-related calcium signals. In addition a number of non-motor related dysfunctions in circadian control, clock genes and associated metabolic, endocrine and sleep-wake activity are briefly addressed, as are late-stage complications in respect of cognitive decline and osteoporosis. Analysis of the network of nutrient effects reveals how beneficial synergies may counter the accumulation and promote clearance of pathogenic alpha-synuclein. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  9. α-Synuclein transgenic mice reveal compensatory increases in Parkinson's disease-associated proteins DJ-1 and parkin and have enhanced α-synuclein and PINK1 levels after rotenone treatment.

    PubMed

    George, Sonia; Mok, Su San; Nurjono, Milawaty; Ayton, Scott; Finkelstein, David I; Masters, Colin L; Li, Qiao-Xin; Culvenor, Janetta G

    2010-10-01

    Parkinson's disease (PD) is a severe neurodegenerative disorder characterised by loss of dopaminergic neurons of the substantia nigra. The pathological hallmarks are cytoplasmic inclusions termed Lewy bodies consisting primarily of aggregated alpha-synuclein (alphaSN). Different lines of transgenic mice have been developed to model PD but have failed to recapitulate the hallmarks of this disease. Since treatment of rodents with the pesticide rotenone can reproduce nigrostriatal cell loss and other features of PD, we aimed to test chronic oral administration of rotenone to transgenic mice over-expressing human alphaSN with the A53T mutation. Initial assessment of this transgenic line for compensatory molecular changes indicated decreased brain beta-synuclein expression and significantly increased levels of the PD-associated oxidative stress response protein, DJ-1, and the E3 ubiquitin ligase enzyme, Parkin. Rotenone treatment of 30 mg/kg for 25 doses over a 35-day period was tolerated in the transgenic mice and resulted in decreased spontaneous locomotor movement and increased cytoplasmic alphaSN expression. The mitochondrial Parkinson's-associated PTEN-induced kinase 1 protein levels were also increased in transgenic mouse brain after rotenone treatment; there was no change in brain dopamine levels or nigrostriatal cell loss. These hA53T alphaSN transgenic mice provide a useful model for presymptomatic Parkinson's features and are valuable for study of associated compensatory changes in early Parkinson's disease stages.

  10. High Throughput Sequencing Identifies MicroRNAs Mediating α-Synuclein Toxicity by Targeting Neuroactive-Ligand Receptor Interaction Pathway in Early Stage of Drosophila Parkinson's Disease Model.

    PubMed

    Kong, Yan; Liang, Xijun; Liu, Lin; Zhang, Dongdong; Wan, Chao; Gan, Zhenji; Yuan, Liudi

    2015-01-01

    Parkinson's disease (PD) is a prevalent neurodegenerative disorder with pathological features including death of dopaminergic neurons in the substantia nigra and intraneuronal accumulations of Lewy bodies. As the main component of Lewy bodies, α-synuclein is implicated in PD pathogenesis by aggregation into insoluble filaments. However, the detailed mechanisms underlying α-synuclein induced neurotoxicity in PD are still elusive. MicroRNAs are ~20nt small RNA molecules that fine-tune gene expression at posttranscriptional level. A plethora of miRNAs have been found to be dysregulated in the brain and blood cells of PD patients. Nevertheless, the detailed mechanisms and their in vivo functions in PD still need further investigation. By using Drosophila PD model expressing α-synuclein A30P, we examined brain miRNA expression with high-throughput small RNA sequencing technology. We found that five miRNAs (dme-miR-133-3p, dme-miR-137-3p, dme-miR-13b-3p, dme-miR-932-5p, dme-miR-1008-5p) were upregulated in PD flies. Among them, miR-13b, miR-133, miR-137 are brain enriched and highly conserved from Drosophila to humans. KEGG pathway analysis using DIANA miR-Path demonstrated that neuroactive-ligand receptor interaction pathway was most likely affected by these miRNAs. Interestingly, miR-137 was predicted to regulate most of the identified targets in this pathway, including dopamine receptor (DopR, D2R), γ-aminobutyric acid (GABA) receptor (GABA-B-R1, GABA-B-R3) and N-methyl-D-aspartate (NMDA) receptor (Nmdar2). The validation experiments showed that the expression of miR-137 and its targets was negatively correlated in PD flies. Further experiments using luciferase reporter assay confirmed that miR-137 could act on specific sites in 3' UTR region of D2R, Nmdar2 and GABA-B-R3, which downregulated significantly in PD flies. Collectively, our findings indicate that α-synuclein could induce the dysregulation of miRNAs, which target neuroactive ligand-receptor interaction

  11. Adsorption and decontamination of α-synuclein from medically and environmentally-relevant surfaces.

    PubMed

    Phan, Hanh T M; Bartz, Jason C; Ayers, Jacob; Giasson, Benoit I; Schubert, Mathias; Rodenhausen, Keith B; Kananizadeh, Negin; Li, Yusong; Bartelt-Hunt, Shannon L

    2018-06-01

    The assembly and accumulation of α-synuclein fibrils are implicated in the development of several neurodegenerative disorders including multiple system atrophy and Parkinson's disease. Pre-existing α-synuclein fibrils can recruit and convert soluble non-fibrillar α-synuclein to the fibrillar form similar to what is observed in prion diseases. This raises concerns regarding attachment of fibrillary α-synuclein to medical instruments and subsequent exposure of patients to α-synuclein similar to what has been observed in iatrogenic transmission of prions. Here, we evaluated adsorption and desorption of α-synuclein to two surfaces: stainless steel and a gold surface coated with a 11-Amino-1-undecanethiol hydrochloride self-assembled-monolayer (SAM) using in-situ combinatorial quartz crystal microbalance with dissipation and spectroscopic ellipsometry. α-Synuclein was found to attach to both surfaces, however, increased α-synuclein adsorption was observed onto the positively charged SAM surface compared to the stainless steel surface. Dynamic light scattering data showed that larger α-synuclein fibrils were preferentially attached to the stainless steel surface when compared with the distributions in the original α-synuclein solution and on the SAM surface. We determined that after attachment, introduction of a 1N NaOH solution could completely remove α-synuclein adsorbed on the stainless steel surface while α-synuclein was retained on the SAM surface. Our results indicate α-synuclein can bind to multiple surface types and that decontamination is surface-dependent. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Chronic administration of cholesterol oximes in mice increases transcription of cytoprotective genes and improves transcriptome alterations induced by alpha-synuclein overexpression in nigrostriatal dopaminergic neurons

    PubMed Central

    Richter, Franziska; Gao, Fuying; Medvedeva, Vera; Lee, Patrick; Bove, Nicholas; Fleming, Sheila M.; Michaud, Magali; Lemesre, Vincent; Patassini, Stefano; De La Rosa, Krystal; Mulligan, Caitlin K.; Sioshansi, Pedrom; Zhu, Chunni; Coppola, Giovanni; Bordet, Thierry; Pruss, Rebecca; Chesselet, Marie-Françoise

    2014-01-01

    Cholesterol-oximes TRO19622 and TRO40303 target outer mitochondrial membrane proteins and have beneficial effects in preclinical models of neurodegenerative diseases leading to their advancement to clinical trials. Dopaminergic neurons degenerate in Parkinson’s disease (PD) and are prone to oxidative stress and mitochondrial dysfunction. In order to provide insights into the neuroprotective potential of TRO19622 and TRO40303 for dopaminergic neurons in vivo, we assessed their effects on gene expression in laser captured nigrostriatal dopaminergic neurons of wildtype mice and of mice that over-express alpha-synuclein, a protein involved in both familial and sporadic forms of PD (Thy1-aSyn mice). Young mice were fed the drugs in food pellets or a control diet from 1 to 4 months of age, approximately 10 months before the appearance of striatal dopamine loss in this model. Unbiased weighted gene co-expression network analysis (WGCNA) of transcriptional changes revealed effects of cholesterol oximes on transcripts related to mitochondria, cytoprotection and anti-oxidant response in wild-type and transgenic mice, including increased transcription of stress defense (e.g. Prdx1, Prdx2, Glrx2, Hspa9, Pink1, Drp1, Trak1) and dopamine-related (Th, Ddc, Gch1, Dat, Vmat2, Drd2, Chnr6a) genes. Even at this young age transgenic mice showed alterations in transcripts implicated in mitochondrial function and oxidative stress (e.g. Bcl-2, Bax, Casp3, Nos2), and both drugs normalized about 20% of these alterations. Young Thy1-aSyn mice exhibit motor deficits that differ from parkinsonism and are established before the onset of treatment; these deficits were not improved by cholesterol oximes. However, high doses of TRO40303 improved olfaction and produced the same effects as dopamine agonists on a challenging beam test, specifically an increase in footslips, an observation congruent with its effects on transcripts involved in dopamine synthesis. High doses of TRO19622 increased

  13. Asparagine endopeptidase cleaves α-synuclein and mediates pathologic activities in Parkinson's disease.

    PubMed

    Zhang, Zhentao; Kang, Seong Su; Liu, Xia; Ahn, Eun Hee; Zhang, Zhaohui; He, Li; Iuvone, P Michael; Duong, Duc M; Seyfried, Nicholas T; Benskey, Matthew J; Manfredsson, Fredric P; Jin, Lingjing; Sun, Yi E; Wang, Jian-Zhi; Ye, Keqiang

    2017-08-01

    Aggregated forms of α-synuclein play a crucial role in the pathogenesis of synucleinopathies such as Parkinson's disease (PD). However, the molecular mechanisms underlying the pathogenic effects of α-synuclein are not completely understood. Here we show that asparagine endopeptidase (AEP) cleaves human α-synuclein, triggers its aggregation and escalates its neurotoxicity, thus leading to dopaminergic neuronal loss and motor impairments in a mouse model. AEP is activated and cleaves human α-synuclein at N103 in an age-dependent manner. AEP is highly activated in human brains with PD, and it fragments α-synuclein, which is found aggregated in Lewy bodies. Overexpression of the AEP-cleaved α-synuclein 1-103 fragment in the substantia nigra induces both dopaminergic neuronal loss and movement defects in mice. In contrast, inhibition of AEP-mediated cleavage of α-synuclein (wild type and A53T mutant) diminishes α-synuclein's pathologic effects. Together, these findings support AEP's role as a key mediator of α-synuclein-related etiopathological effects in PD.

  14. Alpha-synuclein levels in patients with multiple system atrophy: a meta-analysis.

    PubMed

    Yang, Fei; Li, Wan-Jun; Huang, Xu-Sheng

    2018-05-01

    This study evaluates the relationship between multiple system atrophy and α-synuclein levels in the cerebrospinal fluid, plasma and neural tissue. Literature search for relevant research articles was undertaken in electronic databases and study selection was based on a priori eligibility criteria. Random-effects meta-analyses of standardized mean differences in α-synuclein levels between multiple system atrophy patients and normal controls were conducted to obtain the overall and subgroup effect sizes. Meta-regression analyses were performed to evaluate the effect of age, gender and disease severity on standardized mean differences. Data were obtained from 11 studies involving 378 multiple system atrophy patients and 637 healthy controls (age: multiple system atrophy patients 64.14 [95% confidence interval 62.05, 66.23] years; controls 64.16 [60.06, 68.25] years; disease duration: 44.41 [26.44, 62.38] months). Cerebrospinal fluid α-synuclein levels were significantly lower in multiple system atrophy patients than in controls but in plasma and neural tissue, α-synuclein levels were significantly higher in multiple system atrophy patients (standardized mean difference: -0.99 [-1.65, -0.32]; p = 0.001). Percentage of male multiple system atrophy patients was significantly positively associated with the standardized mean differences of cerebrospinal fluid α-synuclein levels (p = 0.029) whereas the percentage of healthy males was not associated with the standardized mean differences of cerebrospinal fluid α-synuclein levels (p = 0.920). In multiple system atrophy patients, α-synuclein levels were significantly lower in the cerebrospinal fluid and were positively associated with the male gender.

  15. Involvement of Cellular Prion Protein in α-Synuclein Transport in Neurons.

    PubMed

    Urrea, Laura; Segura-Feliu, Miriam; Masuda-Suzukake, Masami; Hervera, Arnau; Pedraz, Lucas; García Aznar, José Manuel; Vila, Miquel; Samitier, Josep; Torrents, Eduard; Ferrer, Isidro; Gavín, Rosalina; Hagesawa, Masato; Del Río, José Antonio

    2018-03-01

    The cellular prion protein, encoded by the gene Prnp, has been reported to be a receptor of β-amyloid. Their interaction is mandatory for neurotoxic effects of β-amyloid oligomers. In this study, we aimed to explore whether the cellular prion protein participates in the spreading of α-synuclein. Results demonstrate that Prnp expression is not mandatory for α-synuclein spreading. However, although the pathological spreading of α-synuclein can take place in the absence of Prnp, α-synuclein expanded faster in PrP C -overexpressing mice. In addition, α-synuclein binds strongly on PrP C -expressing cells, suggesting a role in modulating the effect of α-synuclein fibrils.

  16. Genetic association between Alzheimer disease and the alpha-synuclein gene.

    PubMed

    Matsubara, M; Yamagata, H; Kamino, K; Nomura, T; Kohara, K; Kondo, I; Miki, T

    2001-01-01

    alpha-Synuclein has been isolated as a component of amyloid in addition to the major A beta peptide in Alzheimer disease (AD). However, there are conflicting reports regarding the association of alpha-synuclein gene polymorphism with AD. Using a novel and common polymorphism in intron 3, we examined the relationship between AD and alpha-synuclein and apolipoprotein E (ApoE) genes in 183 Japanese AD patients and 210 controls. Carriers of the alpha-synuclein deletion (D) allele had a 2.2-fold increased risk of developing AD than noncarriers in women. The odds ratio for the ApoE epsilon 4 and the alpha-synuclein D allele was 11.4 in women. The results showed that the alpha-synuclein gene is associated with sporadic AD in women, independent of ApoE epsilon 4 status. Copyright 2001 S. Karger AG, Basel

  17. Endonuclease G mediates α-synuclein cytotoxicity during Parkinson's disease.

    PubMed

    Büttner, Sabrina; Habernig, Lukas; Broeskamp, Filomena; Ruli, Doris; Vögtle, F Nora; Vlachos, Manolis; Macchi, Francesca; Küttner, Victoria; Carmona-Gutierrez, Didac; Eisenberg, Tobias; Ring, Julia; Markaki, Maria; Taskin, Asli Aras; Benke, Stefan; Ruckenstuhl, Christoph; Braun, Ralf; Van den Haute, Chris; Bammens, Tine; van der Perren, Anke; Fröhlich, Kai-Uwe; Winderickx, Joris; Kroemer, Guido; Baekelandt, Veerle; Tavernarakis, Nektarios; Kovacs, Gabor G; Dengjel, Jörn; Meisinger, Chris; Sigrist, Stephan J; Madeo, Frank

    2013-11-27

    Malfunctioning of the protein α-synuclein is critically involved in the demise of dopaminergic neurons relevant to Parkinson's disease. Nonetheless, the precise mechanisms explaining this pathogenic neuronal cell death remain elusive. Endonuclease G (EndoG) is a mitochondrially localized nuclease that triggers DNA degradation and cell death upon translocation from mitochondria to the nucleus. Here, we show that EndoG displays cytotoxic nuclear localization in dopaminergic neurons of human Parkinson-diseased patients, while EndoG depletion largely reduces α-synuclein-induced cell death in human neuroblastoma cells. Xenogenic expression of human α-synuclein in yeast cells triggers mitochondria-nuclear translocation of EndoG and EndoG-mediated DNA degradation through a mechanism that requires a functional kynurenine pathway and the permeability transition pore. In nematodes and flies, EndoG is essential for the α-synuclein-driven degeneration of dopaminergic neurons. Moreover, the locomotion and survival of α-synuclein-expressing flies is compromised, but reinstalled by parallel depletion of EndoG. In sum, we unravel a phylogenetically conserved pathway that involves EndoG as a critical downstream executor of α-synuclein cytotoxicity.

  18. The Synaptic Function of α-Synuclein

    PubMed Central

    Burré, Jacqueline

    2015-01-01

    α-Synuclein is an abundant neuronal protein which localizes predominantly to presynaptic terminals, and is strongly linked genetically and pathologically to Parkinson’s disease and other neurodegenerative diseases. While the accumulation of α-synuclein in the form of misfolded oligomers and large aggregates defines multiple neurodegenerative diseases called “synucleinopathies”, its cellular function has remained largely unclear, and is the subject of intense investigation. In this review, I focus on the structural characteristics of α-synuclein, its cellular and subcellular localization, and discuss how this relates to its function in neurons, in particular at the neuronal synapse. PMID:26407041

  19. Role of advanced glycation on aggregation and DNA binding properties of α-synuclein.

    PubMed

    Padmaraju, Vasudevaraju; Bhaskar, Jamuna J; Prasada Rao, Ummiti J S; Salimath, Paramahans V; Rao, K S

    2011-01-01

    Parkinson's disease (PD) is a neurodegenerative disease with multiple etiologies. Advanced glycation end products (AGEs) accumulate in the aging brain and could be one of the reasons for age-related diseases like PD. Oxidative stress also leads to the formation of AGEs and may be involved in neurodegeneration by altering the properties of proteins. α-Synuclein is involved in pathogenesis of PD and there are limited studies on the role of AGE-α-synuclein in neurodegeneration. We studied the aggregation and DNA binding ability of AGE-α-synuclein in vitro. α-Synuclein is glycated using methylglyoxal and formation of AGE-α-synuclein is characterized using fluorescence studies, intrinsic tyrosine fluorescence, and fructosamine estimation. The results indicated that AGE-α-synuclein aggregates into smaller globular-like aggregates compared to fibrils formed with native α-synuclein. Further, it is found that AGE-α-synuclein induced conformational changes in scDNA from B-form to B-C-A mixed conformation. Additionally, AGE-α-synuclein altered DNA integrity as evidenced by the melting temperature, ethidium bromide, and DNAse I sensitivity studies. AGE-α-synuclein converted biphasic Tm to higher monophasic Tm. The Tm of AGE-α-synuclein-scDNA complex is more than that of native α-synuclein-scDNA complex, indicating that AGE-α-synuclein stabilized the uncoiled scDNA. AGE-α-synuclein could stabilize the uncoiled scDNA, as shown by the decrease in the number of ethidium bromide binding molecules per base pair of DNA. DNAse I sensitive studies indicated that both AGE-α-synuclein-scDNA and α-synuclein-scDNA are resistant to DNAse I digestion. The relevance of these findings to neuronal cell death is discussed.

  20. D409H GBA1 mutation accelerates the progression of pathology in A53T α-synuclein transgenic mouse model.

    PubMed

    Kim, Donghoon; Hwang, Heehong; Choi, Seulah; Kwon, Sang Ho; Lee, Suhyun; Park, Jae Hong; Kim, SangMin; Ko, Han Seok

    2018-04-27

    Heterozygous mutations in glucocerebrosidase 1 (GBA1) are a major genetic risk factor for Parkinson's disease and Dementia with Lewy bodies. Mutations in GBA1 leads to GBA1 enzyme deficiency, and GBA1-associated parkinsonism has an earlier age of onset and more progressive parkinsonism. To investigate a potential influence of GBA1 deficiency caused by mutations in GBA1 on the disease progression of PD, GBA1 mice carrying D409H knock-in mutation were crossbred with the human A53T (hA53T) α-synuclein transgenic mice. Here, we show that GBA1 enzyme activity plays a significant role in the hA53T α-synuclein induced α-synucleinopathy. The expression of D409H GBA1 markedly shortens the lifespan of hA53T α-synuclein transgenic mice. Moreover, D409H GBA1 expression exacerbates the formation of insoluble aggregates of α-synuclein, glial activation, neuronal degeneration, and motor abnormalities in the hA53T α-synuclein transgenic mice. Interestingly, the expression of D409H GBA1 results in the loss of dopaminergic neurons in the substantia nigra pars compacta of hA53T transgenic mice. Taken together, these results indicate that GBA1 deficiency due to D409H mutation affects the disease onset and course in hA53T α-synuclein transgenic mice. Therefore, strategies aimed to maintain GBA1 enzyme activity could be employed to develop an effective novel therapy for GBA1 linked-PD and related α-synucleinopathies.

  1. A Blood-Brain Barrier (BBB) Disrupter Is Also a Potent α-Synuclein (α-syn) Aggregation Inhibitor

    PubMed Central

    Shaltiel-Karyo, Ronit; Frenkel-Pinter, Moran; Rockenstein, Edward; Patrick, Christina; Levy-Sakin, Michal; Schiller, Abigail; Egoz-Matia, Nirit; Masliah, Eliezer; Segal, Daniel; Gazit, Ehud

    2013-01-01

    The development of disease-modifying therapy for Parkinson disease has been a main drug development challenge, including the need to deliver the therapeutic agents to the brain. Here, we examined the ability of mannitol to interfere with the aggregation process of α-synuclein in vitro and in vivo in addition to its blood-brain barrier-disrupting properties. Using in vitro studies, we demonstrated the effect of mannitol on α-synuclein aggregation. Although low concentration of mannitol inhibited the formation of fibrils, high concentration significantly decreased the formation of tetramers and high molecular weight oligomers and shifted the secondary structure of α-synuclein from α-helical to a different structure, suggesting alternative potential pathways for aggregation. When administered to a Parkinson Drosophila model, mannitol dramatically corrected its behavioral defects and reduced the amount of α-synuclein aggregates in the brains of treated flies. In the mThy1-human α-synuclein transgenic mouse model, a decrease in α-synuclein accumulation was detected in several brain regions following treatment, suggesting that mannitol promotes α-synuclein clearance in the cell bodies. It appears that mannitol has a general neuroprotective effect in the transgenic treated mice, which includes the dopaminergic system. We therefore suggest mannitol as a basis for a dual mechanism therapeutic agent for the treatment of Parkinson disease. PMID:23637226

  2. Atp13a2-deficient mice exhibit neuronal ceroid lipofuscinosis, limited α-synuclein accumulation and age-dependent sensorimotor deficits

    PubMed Central

    Schultheis, Patrick J.; Fleming, Sheila M.; Clippinger, Amy K.; Lewis, Jada; Tsunemi, Taiji; Giasson, Benoit; Dickson, Dennis W.; Mazzulli, Joseph R.; Bardgett, Mark E.; Haik, Kristi L.; Ekhator, Osunde; Chava, Anil Kumar; Howard, John; Gannon, Matt; Hoffman, Elizabeth; Chen, Yinhuai; Prasad, Vikram; Linn, Stephen C.; Tamargo, Rafael J.; Westbroek, Wendy; Sidransky, Ellen; Krainc, Dimitri; Shull, Gary E.

    2013-01-01

    Mutations in ATP13A2 (PARK9), encoding a lysosomal P-type ATPase, are associated with both Kufor–Rakeb syndrome (KRS) and neuronal ceroid lipofuscinosis (NCL). KRS has recently been classified as a rare genetic form of Parkinson's disease (PD), whereas NCL is a lysosomal storage disorder. Although the transport activity of ATP13A2 has not been defined, in vitro studies show that its loss compromises lysosomal function, which in turn is thought to cause neuronal degeneration. To understand the role of ATP13A2 dysfunction in disease, we disrupted its gene in mice. Atp13a2−/− and Atp13a2+/+ mice were tested behaviorally to assess sensorimotor and cognitive function at multiple ages. In the brain, lipofuscin accumulation, α-synuclein aggregation and dopaminergic pathology were measured. Behaviorally, Atp13a2−/− mice displayed late-onset sensorimotor deficits. Accelerated deposition of autofluorescent storage material (lipofuscin) was observed in the cerebellum and in neurons of the hippocampus and the cortex of Atp13a2−/− mice. Immunoblot analysis showed increased insoluble α-synuclein in the hippocampus, but not in the cortex or cerebellum. There was no change in the number of dopaminergic neurons in the substantia nigra or in striatal dopamine levels in aged Atp13a2−/− mice. These results show that the loss of Atp13a2 causes sensorimotor impairments, α-synuclein accumulation as occurs in PD and related synucleinopathies, and accumulation of lipofuscin deposits characteristic of NCL, thus providing the first direct demonstration that null mutations in Atp13a2 can cause pathological features of both diseases in the same organism. PMID:23393156

  3. Wild-Type Monomeric α-Synuclein Can Impair Vesicle Endocytosis and Synaptic Fidelity via Tubulin Polymerization at the Calyx of Held.

    PubMed

    Eguchi, Kohgaku; Taoufiq, Zacharie; Thorn-Seshold, Oliver; Trauner, Dirk; Hasegawa, Masato; Takahashi, Tomoyuki

    2017-06-21

    α-Synuclein is a presynaptic protein the function of which has yet to be identified, but its neuronal content increases in patients of synucleinopathies including Parkinson's disease. Chronic overexpression of α-synuclein reportedly expresses various phenotypes of synaptic dysfunction, but the primary target of its toxicity has not been determined. To investigate this, we acutely loaded human recombinant α-synuclein or its pathological mutants in their monomeric forms into the calyces of Held presynaptic terminals in slices from auditorily mature and immature rats of either sex. Membrane capacitance measurements revealed significant and specific inhibitory effects of WT monomeric α-synuclein on vesicle endocytosis throughout development. However, the α-synuclein A53T mutant affected vesicle endocytosis only at immature calyces, whereas the A30P mutant had no effect throughout. The endocytic impairment by WT α-synuclein was rescued by intraterminal coloading of the microtubule (MT) polymerization blocker nocodazole. Furthermore, it was reversibly rescued by presynaptically loaded photostatin-1, a photoswitcheable inhibitor of MT polymerization, in a light-wavelength-dependent manner. In contrast, endocytic inhibition by the A53T mutant at immature calyces was not rescued by nocodazole. Functionally, presynaptically loaded WT α-synuclein had no effect on basal synaptic transmission evoked at a low frequency, but significantly attenuated exocytosis and impaired the fidelity of neurotransmission during prolonged high-frequency stimulation. We conclude that monomeric WT α-synuclein primarily inhibits vesicle endocytosis via MT overassembly, thereby impairing high-frequency neurotransmission. SIGNIFICANCE STATEMENT Abnormal α-synuclein abundance is associated with synucleinopathies including Parkinson's disease, but neither the primary target of α-synuclein toxicity nor its mechanism is identified. Here, we loaded monomeric α-synuclein directly into mammalian

  4. Parkinson's disease and α-synuclein expression.

    PubMed

    Devine, Michael J; Gwinn, Katrina; Singleton, Andrew; Hardy, John

    2011-10-01

    Genetic studies of Parkinson's disease over the last decade or more have revolutionized our understanding of this condition. α-Synuclein was the first gene to be linked to Parkinson's disease, and is arguably the most important: the protein is the principal constituent of Lewy bodies, and variation at its locus is the major genetic risk factor for sporadic disease. Intriguingly, duplications and triplications of the locus, as well as point mutations, cause familial disease. Therefore, subtle alterations of α-synuclein expression can manifest with a dramatic phenotype. We outline the clinical impact of α-synuclein locus multiplications, and the implications that this has for Parkinson's disease pathogenesis. Finally, we discuss potential strategies for disease-modifying therapies for this currently incurable disorder. Copyright © 2011 Movement Disorder Society.

  5. Alpha-synuclein mitochondrial interaction leads to irreversible translocation and complex I impairment.

    PubMed

    Martínez, Jimena H; Fuentes, Federico; Vanasco, Virginia; Alvarez, Silvia; Alaimo, Agustina; Cassina, Adriana; Coluccio Leskow, Federico; Velazquez, Francisco

    2018-08-01

    α-synuclein is involved in both familial and sporadic Parkinson's disease. Although its interaction with mitochondria has been well documented, several aspects remains unknown or under debate such as the specific sub-mitochondrial localization or the dynamics of the interaction. It has been suggested that α-synuclein could only interact with ER-associated mitochondria. The vast use of model systems and experimental conditions makes difficult to compare results and extract definitive conclusions. Here we tackle this by analyzing, in a simplified system, the interaction between purified α-synuclein and isolated rat brain mitochondria. This work shows that wild type α-synuclein interacts with isolated mitochondria and translocates into the mitochondrial matrix. This interaction and the irreversibility of α-synuclein translocation depend on incubation time and α-synuclein concentration. FRET experiments show that α-synuclein localizes close to components of the TOM complex suggesting a passive transport of α-synuclein through the outer membrane. In addition, α-synuclein binding alters mitochondrial function at the level of Complex I leading to a decrease in ATP synthesis and an increase of ROS production. Copyright © 2018. Published by Elsevier Inc.

  6. Mutant alpha-synuclein overexpression mediates early proinflammatory activity.

    PubMed

    Su, Xiaomin; Federoff, Howard J; Maguire-Zeiss, Kathleen A

    2009-10-01

    Microglia provide immune surveillance for the brain through both the removal of cellular debris and protection against infection by microorganisms and "foreign" molecules. Upon activation, microglia display an altered morphology and increased expression of proinflammatory molecules. Increased numbers of activated microglia have been identified in a number of neurodegenerative diseases including Parkinson's disease (PD). What remains to be determined is whether activated microglia result from ongoing cell death or are involved in disease initiation and progression. To address this question we utilized a transgenic mouse model that expresses a mutated form of a key protein involved in Parkinson's disease, alpha-synuclein. Herein, we report an increase in activated microglia and proinflammatory molecules in 1-month-old transgenic mice well before cell death occurs in this model. Frank microglial activation is resolved by 6 months of age while a subset of proinflammatory molecules remain elevated for 12 months. Both tyrosine hydroxylase mRNA expression and alpha-synuclein protein are decreased in the striatum of older animals evidence of dystrophic neuritic projections. To determine whether mutated alpha-synuclein could directly activate microglia primary microglia-enriched cell cultures were treated with exogenous mutated alpha-synuclein. The data reveal an increase in activated microglia and proinflammatory molecules due to direct interaction with mutated alpha-synuclein. Together, these data demonstrate that mutated alpha-synuclein mediates a proinflammatory response in microglia and this activity may participate in PD pathogenesis.

  7. Interaction of Synuclein and Inflammation in Dopaminergic Neurodegeneration

    DTIC Science & Technology

    2010-07-01

    synuclein in cell culture. Specific Aim II In vivo studies: we are now optimizing immunostaining for human -synuclein in order to distinguish...responsible for this response. Recent cell culture experiments seem to point us in the right direction for the answer as it has been shown that human BE-M17...synuclein. Furthermore, Zhou et al (2002) showed that, in primary cell cultures derived from the embryonic human mesencephalon overexpressing either

  8. The Identification of Alpha-Synuclein as the First Parkinson Disease Gene

    PubMed Central

    Nussbaum, Robert L.

    2017-01-01

    In this Commentary, I describe the events that led from an NINDS-sponsored Workshop on Parkinson Disease Research in 1995, where I was asked to speak about the genetics of Parkinson disease, to the identification a mere two years later of a mutation in alpha-synuclein as the cause of autosomal dominant Parkinson disease in the Contursi kindred. I review the steps we took to first map and then find the mutation in the alpha-synuclein locus and describe the obstacles and the role of serendipity in facilitating the work. Although alpha-synuclein mutations are a rare cause of hereditary PD, the importance of this finding goes far beyond the rare families with hereditary disease because it pinpointed alpha-synuclein as a key contributor to the far more common sporadic form of Parkinson disease. This work confirms William Harvey’s observation from 350 years ago that studying rarer forms of a disease is an excellent way to understand the more common forms of that disease. The identification of synuclein’s role in hereditary Parkinson disease has opened new avenues of research into the pathogenesis and potential treatments of the common form of Parkinson disease that affects many millions of Americans and tens of millions of human beings worldwide. PMID:28282812

  9. α-Synuclein aggregation, seeding and inhibition by scyllo-inositol

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ibrahim, Tarek; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, M4N 3M5, ON; McLaurin, JoAnne, E-mail: jmclaurin@sri.utoronto.ca

    2016-01-15

    Recent literature demonstrates the accelerated aggregation of α-synuclein, a protein implicated in the pathogenesis of Parkinson's disease (PD), by the presence of preformed fibrillar conformers in vitro. Furthermore, these preformed fibrillar seeds are suggested to accelerate pathological induction in vivo when injected into the brains of mice. Variation in the results of in vivo studies is proposed to be caused by α-synuclein conformational variants. To investigate the impact of amino acid sequence on seeding efficiency, human and mouse α-synuclein seeds, which vary at 7 amino acid residues, were generated and cross-seeding kinetics studied. Using transmission electron microscopy (TEM), we confirmed that mouse α-synucleinmore » aggregated more rapidly than human α-synuclein. Subsequently, we determined that seeding of human and mouse α-synuclein was more rapid in the presence of seeds generated from the same species. In addition, an established amyloid inhibitor, scyllo-inositol, was examined for potential inhibitory effects on α-synuclein aggregation. TEM analysis of protein:inhibitor assays demonstrated that scyllo-inositol inhibits the aggregation of α-synuclein, suggesting the therapeutic potential of the small molecule in PD. - Highlights: • Mouse α-syn fibrillizes in a significantly shorter timeframe than human α-syn. • Seeding of monomers is more efficient when seeds originate from the same species. • scyllo-Inositol has anti-aggregation effects on mouse and human α-syn.« less

  10. Mitochondrial translocation of α-synuclein is promoted by intracellular acidification

    PubMed Central

    Cole, Nelson B.; DiEuliis, Diane; Leo, Paul; Mitchell, Drake C.; Nussbaum, Robert L.

    2008-01-01

    Mitochondrial dysfunction plays a central role in the selective vulnerability of dopaminergic neurons in Parkinson’s disease (PD) and is influenced by both environmental and genetic factors. Expression of the PD protein α-synuclein or its familial mutants often sensitizes neurons to oxidative stress and to damage by mitochondrial toxins. This effect is thought to be indirect, since little evidence physically linking α-synuclein to mitochondria has been reported. Here, we show that the distribution of α-synuclein within neuronal and non-neuronal cells is dependent on intracellular pH. Cytosolic acidification induces translocation of α-synuclein from the cytosol onto the surface of mitochondria. Translocation occurs rapidly under artificially-induced low pH conditions and as a result of pH changes during oxidative or metabolic stress. Binding is likely facilitated by low pH-induced exposure of the mitochondria-specific lipid cardiolipin. These results imply a direct role for α-synuclein in mitochondrial physiology, especially under pathological conditions, and in principle, link α-synuclein to other PD genes in regulating mitochondrial homeostasis. PMID:18440504

  11. A Focus on the Beneficial Effects of Alpha Synuclein and a Re-Appraisal of Synucleinopathies

    PubMed Central

    Ryskalin, Larisa; Busceti, Carla L.; Limanaqi, Fiona; Biagioni, Francesca; Gambardella, Stefano; Fornai, Francesco

    2018-01-01

    Alpha synuclein (α-syn) belongs to a class of proteins which are commonly considered to play a detrimental role in neuronal survival. This assumption is based on the occurrence of a severe neuronal degeneration in patients carrying a multiplication of the α-syn gene (SNCA) and in a variety of experi-mental models, where overexpression of α-syn leads to cell death and neurological impairment. In these conditions, a higher amount of normally structured α-syn produces a damage, which is even worse com-pared with that produced by α-syn owning an abnormal structure (as occurring following point gene muta-tions). In line with this, knocking out the expression of α-syn is reported to protect from specific neurotox-ins such as 1-methyl, 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP). In the present review we briefly dis-cuss these well-known detrimental effects but we focus on findings showing that, in specific conditions α-syn is beneficial for cell survival. This occurs during methamphetamine intoxication which is counteracted by endogenous α-syn. Similarly, the dysfunction of the chaperone cysteine-string protein-alpha leads to cell pathology which is counteracted by over-expressing α-syn. In line with this, an increased expression of α-syn protects against oxidative damage produced by dopamine. Remarkably, when the lack of α-syn is combined with a depletion of β- and γ- synucleins, alterations in brain structure and function occur. This review tries to balance the evidence showing a beneficial effect with the bulk of data reporting a detri-mental effect of endogenous α-syn. The specific role of α-syn as a chaperone protein is discussed to ex-plain such a dual effect. PMID:29150919

  12. A Focus on the Beneficial Effects of Alpha Synuclein and a Re-Appraisal of Synucleinopathies.

    PubMed

    Ryskalin, Larisa; Busceti, Carla L; Limanaqi, Fiona; Biagioni, Francesca; Gambardella, Stefano; Fornai, Francesco

    2018-01-01

    Alpha synuclein (α-syn) belongs to a class of proteins which are commonly considered to play a detrimental role in neuronal survival. This assumption is based on the occurrence of a severe neuronal degeneration in patients carrying a multiplication of the α-syn gene (SNCA) and in a variety of experimental models, where overexpression of α-syn leads to cell death and neurological impairment. In these conditions, a higher amount of normally structured α-syn produces a damage, which is even worse compared with that produced by α-syn owning an abnormal structure (as occurring following point gene mutations). In line with this, knocking out the expression of α-syn is reported to protect from specific neurotoxins such as 1-methyl, 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP). In the present review we briefly discuss these well-known detrimental effects but we focus on findings showing that, in specific conditions α-syn is beneficial for cell survival. This occurs during methamphetamine intoxication which is counteracted by endogenous α-syn. Similarly, the dysfunction of the chaperone cysteine-string protein- alpha leads to cell pathology which is counteracted by over-expressing α-syn. In line with this, an increased expression of α-syn protects against oxidative damage produced by dopamine. Remarkably, when the lack of α-syn is combined with a depletion of β- and γ- synucleins, alterations in brain structure and function occur. This review tries to balance the evidence showing a beneficial effect with the bulk of data reporting a detrimental effect of endogenous α-syn. The specific role of α-syn as a chaperone protein is discussed to explain such a dual effect. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  13. Large α-synuclein oligomers inhibit neuronal SNARE-mediated vesicle docking

    PubMed Central

    Choi, Bong-Kyu; Choi, Mal-Gi; Kim, Jae-Yeol; Yang, Yoosoo; Lai, Ying; Kweon, Dae-Hyuk; Lee, Nam Ki; Shin, Yeon-Kyun

    2013-01-01

    Parkinson disease and dementia with Lewy bodies are featured with the formation of Lewy bodies composed mostly of α-synuclein (α-Syn) in the brain. Although evidence indicates that the large oligomeric or protofibril forms of α-Syn are neurotoxic agents, the detailed mechanisms of the toxic functions of the oligomers remain unclear. Here, we show that large α-Syn oligomers efficiently inhibit neuronal SNARE-mediated vesicle lipid mixing. Large α-Syn oligomers preferentially bind to the N-terminal domain of a vesicular SNARE protein, synaptobrevin-2, which blocks SNARE-mediated lipid mixing by preventing SNARE complex formation. In sharp contrast, the α-Syn monomer has a negligible effect on lipid mixing even with a 30-fold excess compared with the case of large α-Syn oligomers. Thus, the results suggest that large α-Syn oligomers function as inhibitors of dopamine release, which thus provides a clue, at the molecular level, to their neurotoxicity. PMID:23431141

  14. Axonal damage and loss of connectivity in nigrostriatal and mesolimbic dopamine pathways in early Parkinson's disease.

    PubMed

    Caminiti, Silvia Paola; Presotto, Luca; Baroncini, Damiano; Garibotto, Valentina; Moresco, Rosa Maria; Gianolli, Luigi; Volonté, Maria Antonietta; Antonini, Angelo; Perani, Daniela

    2017-01-01

    A progressive loss of dopamine neurons in the substantia nigra (SN) is considered the main feature of idiopathic Parkinson's disease (PD). Recent neuropathological evidence however suggests that the axons of the nigrostriatal dopaminergic system are the earliest target of α-synuclein accumulation in PD, thus the principal site for vulnerability. Whether this applies to in vivo PD, and also to the mesolimbic system has not been investigated yet. We used [ 11 C]FeCIT PET to measure presynaptic dopamine transporter (DAT) activity in both nigrostriatal and mesolimbic systems, in 36 early PD patients (mean disease duration in months ± SD 21.8 ± 10.7) and 14 healthy controls similar for age. We also performed anatomically-driven partial correlation analysis to evaluate possible changes in the connectivity within both the dopamine networks at an early clinical phase. In the nigrostriatal system, we found a severe DAT reduction in the afferents to the dorsal putamen (DPU) (η 2  = 0.84), whereas the SN was the less affected region (η 2  = 0.31). DAT activity in the ventral tegmental area (VTA) and the ventral striatum (VST) were also reduced in the patient group, but to a lesser degree (VST η 2  = 0.71 and VTA η 2  = 0.31). In the PD patients compared to the controls, there was a marked decrease in dopamine network connectivity between SN and DPU nodes, supporting the significant derangement in the nigrostriatal pathway. These results suggest that neurodegeneration in the dopamine pathways is initially more prominent in the afferent axons and more severe in the nigrostriatal system. Considering PD as a disconnection syndrome starting from the axons, it would justify neuroprotective interventions even if patients have already manifested clinical symptoms.

  15. High Throughput Sequencing Identifies MicroRNAs Mediating α-Synuclein Toxicity by Targeting Neuroactive-Ligand Receptor Interaction Pathway in Early Stage of Drosophila Parkinson's Disease Model

    PubMed Central

    Kong, Yan; Liang, Xijun; Liu, Lin; Zhang, Dongdong; Wan, Chao; Gan, Zhenji; Yuan, Liudi

    2015-01-01

    Parkinson’s disease (PD) is a prevalent neurodegenerative disorder with pathological features including death of dopaminergic neurons in the substantia nigra and intraneuronal accumulations of Lewy bodies. As the main component of Lewy bodies, α-synuclein is implicated in PD pathogenesis by aggregation into insoluble filaments. However, the detailed mechanisms underlying α-synuclein induced neurotoxicity in PD are still elusive. MicroRNAs are ~20nt small RNA molecules that fine-tune gene expression at posttranscriptional level. A plethora of miRNAs have been found to be dysregulated in the brain and blood cells of PD patients. Nevertheless, the detailed mechanisms and their in vivo functions in PD still need further investigation. By using Drosophila PD model expressing α-synuclein A30P, we examined brain miRNA expression with high-throughput small RNA sequencing technology. We found that five miRNAs (dme-miR-133-3p, dme-miR-137-3p, dme-miR-13b-3p, dme-miR-932-5p, dme-miR-1008-5p) were upregulated in PD flies. Among them, miR-13b, miR-133, miR-137 are brain enriched and highly conserved from Drosophila to humans. KEGG pathway analysis using DIANA miR-Path demonstrated that neuroactive-ligand receptor interaction pathway was most likely affected by these miRNAs. Interestingly, miR-137 was predicted to regulate most of the identified targets in this pathway, including dopamine receptor (DopR, D2R), γ-aminobutyric acid (GABA) receptor (GABA-B-R1, GABA-B-R3) and N-methyl-D-aspartate (NMDA) receptor (Nmdar2). The validation experiments showed that the expression of miR-137 and its targets was negatively correlated in PD flies. Further experiments using luciferase reporter assay confirmed that miR-137 could act on specific sites in 3’ UTR region of D2R, Nmdar2 and GABA-B-R3, which downregulated significantly in PD flies. Collectively, our findings indicate that α-synuclein could induce the dysregulation of miRNAs, which target neuroactive ligand

  16. Tunneling nanotubes spread fibrillar α-synuclein by intercellular trafficking of lysosomes.

    PubMed

    Abounit, Saïda; Bousset, Luc; Loria, Frida; Zhu, Seng; de Chaumont, Fabrice; Pieri, Laura; Olivo-Marin, Jean-Christophe; Melki, Ronald; Zurzolo, Chiara

    2016-10-04

    Synucleinopathies such as Parkinson's disease are characterized by the pathological deposition of misfolded α-synuclein aggregates into inclusions throughout the central and peripheral nervous system. Mounting evidence suggests that intercellular propagation of α-synuclein aggregates may contribute to the neuropathology; however, the mechanism by which spread occurs is not fully understood. By using quantitative fluorescence microscopy with co-cultured neurons, here we show that α-synuclein fibrils efficiently transfer from donor to acceptor cells through tunneling nanotubes (TNTs) inside lysosomal vesicles. Following transfer through TNTs, α-synuclein fibrils are able to seed soluble α-synuclein aggregation in the cytosol of acceptor cells. We propose that donor cells overloaded with α-synuclein aggregates in lysosomes dispose of this material by hijacking TNT-mediated intercellular trafficking. Our findings thus reveal a possible novel role of TNTs and lysosomes in the progression of synucleinopathies. © 2016 The Authors.

  17. Association between the dopamine D3 receptor gene locus (DRD3) and unipolar affective disorder.

    PubMed

    Dikeos, D G; Papadimitriou, G N; Avramopoulos, D; Karadima, G; Daskalopoulou, E G; Souery, D; Mendlewicz, J; Vassilopoulos, D; Stefanis, C N

    1999-12-01

    Dopamine neurotransmission has been implicated in the pathophysiology of schizophrenia and, more recently, affective disorders. Among the dopamine receptors, D3 can be considered as particularly related to affective disorders due to its neuroanatomical localization in the limbic region of the brain and its relation to the serotoninergic activity of the CNS. The possible involvement of dopamine receptor D3 in unipolar (UP) major depression was investigated by a genetic association study of the D3 receptor gene locus (DRD3) on 36 UP patients and 38 ethnically matched controls. An allelic association of DRD3 (Bal I polymorphism) and UP illness was observed, with the Gly-9 allele (allele '2', 206/98 base-pairs long) being more frequent in patients than in controls (49% vs 29%, P < 0.02). The genotypes containing this allele (1-2 and 2-2) were found in 75% of patients vs 50% of controls (P < 0.03, odds ratio = 3.00, 95% CI = 1.12-8.05). The effect of the genotype remained significant (P < 0.02) after sex and family history were controlled by a multiple linear regression analysis. These results further support the hypothesis that dopaminergic mechanisms may be implicated in the pathogenesis of affective disorder. More specifically, the '2' allele of the dopamine receptor D3 gene seems to be associated with unipolar depression and can be considered as a 'phenotypic modifier' for major psychiatric disorders.

  18. Curcumin Treatment Improves Motor Behavior in α-Synuclein Transgenic Mice

    PubMed Central

    Spinelli, Kateri J.; Osterberg, Valerie R.; Meshul, Charles K.; Soumyanath, Amala; Unni, Vivek K.

    2015-01-01

    The curry spice curcumin plays a protective role in mouse models of neurodegenerative diseases, and can also directly modulate aggregation of α-synuclein protein in vitro, yet no studies have described the interaction of curcumin and α-synuclein in genetic synucleinopathy mouse models. Here we examined the effect of chronic and acute curcumin treatment in the Syn-GFP mouse line, which overexpresses wild-type human α-synuclein protein. We discovered that curcumin diet intervention significantly improved gait impairments and resulted in an increase in phosphorylated forms of α-synuclein at cortical presynaptic terminals. Acute curcumin treatment also caused an increase in phosphorylated α-synuclein in terminals, but had no direct effect on α-synuclein aggregation, as measured by in vivo multiphoton imaging and Proteinase-K digestion. Using LC-MS/MS, we detected ~5 ng/mL and ~12 ng/mL free curcumin in the plasma of chronic or acutely treated mice, with a glucuronidation rate of 94% and 97%, respectively. Despite the low plasma levels and extensive metabolism of curcumin, these results show that dietary curcumin intervention correlates with significant behavioral and molecular changes in a genetic synucleinopathy mouse model that mimics human disease. PMID:26035833

  19. Calcium accelerates SNARE-mediated lipid mixing through modulating α-synuclein membrane interaction.

    PubMed

    Zhang, Zeting; Jiang, Xin; Xu, Danrui; Zheng, Wenwen; Liu, Maili; Li, Conggang

    2018-04-04

    α-Synuclein is involved in Parkinson's disease, and its interaction with cell membrane is vital to its pathological and physiological functions. We have shown that Ca 2+ can regulate α-synuclein membrane interaction, but the physiological role of Ca 2+ in modulating α-synuclein membrane interaction is still unexplored. Based on the previous findings that α-synuclein inhibits membrane fusion and its inhibitory effect is highly related to its membrane binding, here we employed solution state Nuclear Magnetic Resonance (NMR) spectroscopy and the ensemble fluorescence fusion assay to show that Ca 2+ can modulate the inhibitory effect of α-synuclein on SNARE-mediated membrane fusion through disrupting α-synuclein membrane interaction, resulting in acceleration of SNARE-mediated membrane fusion. These results suggest a modulatory effect of Ca 2+ on membrane mediated normal function of α-synuclein, which of importance for the study of the Parkinson's disease. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. The dopamine hypothesis of bipolar affective disorder: the state of the art and implications for treatment

    PubMed Central

    Ashok, A H; Marques, T R; Jauhar, S; Nour, M M; Goodwin, G M; Young, A H; Howes, O D

    2017-01-01

    Bipolar affective disorder is a common neuropsychiatric disorder. Although its neurobiological underpinnings are incompletely understood, the dopamine hypothesis has been a key theory of the pathophysiology of both manic and depressive phases of the illness for over four decades. The increased use of antidopaminergics in the treatment of this disorder and new in vivo neuroimaging and post-mortem studies makes it timely to review this theory. To do this, we conducted a systematic search for post-mortem, pharmacological, functional magnetic resonance and molecular imaging studies of dopamine function in bipolar disorder. Converging findings from pharmacological and imaging studies support the hypothesis that a state of hyperdopaminergia, specifically elevations in D2/3 receptor availability and a hyperactive reward processing network, underlies mania. In bipolar depression imaging studies show increased dopamine transporter levels, but changes in other aspects of dopaminergic function are inconsistent. Puzzlingly, pharmacological evidence shows that both dopamine agonists and antidopaminergics can improve bipolar depressive symptoms and perhaps actions at other receptors may reconcile these findings. Tentatively, this evidence suggests a model where an elevation in striatal D2/3 receptor availability would lead to increased dopaminergic neurotransmission and mania, whilst increased striatal dopamine transporter (DAT) levels would lead to reduced dopaminergic function and depression. Thus, it can be speculated that a failure of dopamine receptor and transporter homoeostasis might underlie the pathophysiology of this disorder. The limitations of this model include its reliance on pharmacological evidence, as these studies could potentially affect other monoamines, and the scarcity of imaging evidence on dopaminergic function. This model, if confirmed, has implications for developing new treatment strategies such as reducing the dopamine synthesis and/or release in

  1. Plasma exosomal α-synuclein is likely CNS-derived and increased in Parkinson’s disease

    PubMed Central

    Cook, Travis J.; Bullock, Kristin M.; Zhao, Yanchun; Ginghina, Carmen; Li, Yanfei; Aro, Patrick; Dator, Romel; He, Chunmei; Hipp, Michael J.; Zabetian, Cyrus P.; Peskind, Elaine R.; Hu, Shu-Ching; Quinn, Joseph F.; Galasko, Douglas R.; Banks, William A.; Zhang, Jing

    2014-01-01

    Extracellular α-synuclein is important in the pathogenesis of Parkinson disease (PD) and also as a potential biomarker when tested in the cerebrospinal fluid (CSF). The performance of blood plasma or serum α-synuclein as a biomarker has been found to be inconsistent and generally ineffective, largely due to the contribution of peripherally derived α-synuclein. In this study, we discovered, via an intracerebroventricular injection of radiolabeled α-synuclein into mouse brain, that CSF α-synuclein was readily transported to blood, with a small portion being contained in exosomes that are relatively specific to the central nervous system (CNS). Consequently, we developed a technique to evaluate the levels of α-synuclein in these exosomes in individual plasma samples. When applied to a large cohort of clinical samples (267 PD, 215 controls), we found that in contrast to CSF α-synuclein concentrations, which are consistently reported to be lower in PD patients compared to controls, the levels of plasma exosomal α-synuclein were substantially higher in PD patients, suggesting an increased efflux of the protein to the peripheral blood of these patients. Furthermore, although no association was observed between plasma exosomal and CSF α-synuclein, a significant correlation between plasma exosomal α-synuclein and disease severity (r=0.176, p=0.004) was observed, and the diagnostic sensitivity and specificity achieved by plasma exosomal α-synuclein were comparable to those determined by CSF α-synuclein. Further studies are clearly needed to elucidate the mechanism involved in the transport of CNS α-synuclein to the periphery, which may lead to a more convenient and robust assessment of PD clinically. PMID:24997849

  2. Parkinson’s Disease and α-synuclein Expression

    PubMed Central

    Devine, Michael J.; Gwinn, Katrina; Singleton, Andrew; Hardy, John

    2015-01-01

    Genetic studies of Parkinson’s disease over the last decade or more have revolutionized our understanding of this condition. α-Synuclein was the first gene to be linked to Parkinson’s disease, and is arguably the most important: the protein is the principal constituent of Lewy bodies, and variation at its locus is the major genetic risk factor for sporadic disease. Intriguingly, duplications and triplications of the locus, as well as point mutations, cause familial disease. Therefore, subtle alterations of α-synuclein expression can manifest with a dramatic phenotype. We outline the clinical impact of α-synuclein locus multiplications, and the implications that this has for Parkinson’s disease pathogenesis. Finally, we discuss potential strategies for disease-modifying therapies for this currently incurable disorder. PMID:21887711

  3. Neuron-to-neuron transmission of α-synuclein fibrils through axonal transport

    PubMed Central

    Freundt, Eric C.; Maynard, Nate; Clancy, Eileen K.; Roy, Shyamali; Bousset, Luc; Sourigues, Yannick; Covert, Markus; Melki, Ronald; Kirkegaard, Karla; Brahic, Michel

    2012-01-01

    Objective The lesions of Parkinson's disease spread through the brain in a characteristic pattern that corresponds to axonal projections. Previous observations suggest that misfolded α-synuclein could behave as a prion, moving from neuron to neuron and causing endogenous α-synuclein to misfold. Here, we characterized and quantified the axonal transport of α-synuclein fibrils and showed that fibrils could be transferred from axons to second-order neurons following anterograde transport. Methods We grew primary cortical mouse neurons in microfluidic devices to separate soma from axonal projections in fluidically isolated microenvironments. We used live-cell imaging and immunofluorescence to characterize the transport of fluorescent α-synuclein fibrils and their transfer to second-order neurons. Results Fibrillar α-synuclein was internalized by primary neurons and transported in axons with kinetics consistent with slow component-b of axonal transport (fast axonal transport with saltatory movement). Fibrillar α-synuclein was readily observed in the cell bodies of second-order neurons following anterograde axonal transport. Axon-to-soma transfer appeared not to require synaptic contacts. Interpretation These results support the hypothesis that the progression of Parkinson's disease can be caused by neuron-to-neuron spread of α-synuclein aggregates and that the anatomical pattern of progression of lesions between axonally connected areas results from the axonal transport of such aggregates. That the transfer did not appear to be transsynaptic gives hope that α-synuclein fibrils could be intercepted by drugs during the extra-cellular phase of their journey. PMID:23109146

  4. α-Synuclein binds the KATP channel at insulin-secretory granules and inhibits insulin secretion

    PubMed Central

    Geng, Xuehui; Lou, Haiyan; Wang, Jian; Li, Lehong; Swanson, Alexandra L.; Sun, Ming; Beers-Stolz, Donna; Watkins, Simon; Perez, Ruth G.

    2011-01-01

    α-Synuclein has been studied in numerous cell types often associated with secretory processes. In pancreatic β-cells, α-synuclein might therefore play a similar role by interacting with organelles involved in insulin secretion. We tested for α-synuclein localizing to insulin-secretory granules and characterized its role in glucose-stimulated insulin secretion. Immunohistochemistry and fluorescent sulfonylureas were used to test for α-synuclein localization to insulin granules in β-cells, immunoprecipitation with Western blot analysis for interaction between α-synuclein and KATP channels, and ELISA assays for the effect of altering α-synuclein expression up or down on insulin secretion in INS1 cells or mouse islets, respectively. Differences in cellular phenotype between α-synuclein knockout and wild-type β-cells were found by using confocal microscopy to image the fluorescent insulin biosensor Ins-C-emGFP and by using transmission electron microscopy. The results show that anti-α-synuclein antibodies labeled secretory organelles within β-cells. Anti-α-synuclein antibodies colocalized with KATP channel, anti-insulin, and anti-C-peptide antibodies. α-Synuclein coimmunoprecipitated in complexes with KATP channels. Expression of α-synuclein downregulated insulin secretion at 2.8 mM glucose with little effect following 16.7 mM glucose stimulation. α-Synuclein knockout islets upregulated insulin secretion at 2.8 and 8.4 mM but not 16.7 mM glucose, consistent with the depleted insulin granule density at the β-cell surface membranes observed in these islets. These findings demonstrate that α-synuclein interacts with KATP channels and insulin-secretory granules and functionally acts as a brake on secretion that glucose stimulation can override. α-Synuclein might play similar roles in diabetes as it does in other degenerative diseases, including Alzheimer's and Parkinson's diseases. PMID:20858756

  5. α-Synuclein-induced dopaminergic neurodegeneration in a rat model of Parkinson's disease occurs independent of ATP13A2 (PARK9).

    PubMed

    Daniel, Guillaume; Musso, Alessandra; Tsika, Elpida; Fiser, Aris; Glauser, Liliane; Pletnikova, Olga; Schneider, Bernard L; Moore, Darren J

    2015-01-01

    Mutations in the ATP13A2 (PARK9) gene cause early-onset, autosomal recessive Parkinson's disease (PD) and Kufor-Rakeb syndrome. ATP13A2 mRNA is spliced into three distinct isoforms encoding a P5-type ATPase involved in regulating heavy metal transport across vesicular membranes. Here, we demonstrate that three ATP13A2 mRNA isoforms are expressed in the normal human brain and are modestly increased in the cingulate cortex of PD cases. ATP13A2 can mediate protection toward a number of stressors in mammalian cells and can protect against α-synuclein-induced toxicity in cellular and invertebrate models of PD. Using a primary cortical neuronal model combined with lentiviral-mediated gene transfer, we demonstrate that human ATP13A2 isoforms 1 and 2 display selective neuroprotective effects toward toxicity induced by manganese and hydrogen peroxide exposure through an ATPase-independent mechanism. The familial PD mutations, F182L and G504R, abolish the neuroprotective effects of ATP13A2 consistent with a loss-of-function mechanism. We further demonstrate that the AAV-mediated overexpression of human ATP13A2 is not sufficient to attenuate dopaminergic neurodegeneration, neuropathology, and striatal dopamine and motoric deficits induced by human α-synuclein expression in a rat model of PD. Intriguingly, the delivery of an ATPase-deficient form of ATP13A2 (D513N) to the substantia nigra is sufficient to induce dopaminergic neuronal degeneration and motor deficits in rats, potentially suggesting a dominant-negative mechanism of action. Collectively, our data demonstrate a distinct lack of ATP13A2-mediated protection against α-synuclein-induced neurotoxicity in the rat nigrostriatal dopaminergic pathway, and limited neuroprotective capacity overall, and raise doubts about the potential of ATP13A2 as a therapeutic target for PD. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Targeting α-synuclein oligomers by protein-fragment complementation for drug discovery in synucleinopathies.

    PubMed

    Moussaud, Simon; Malany, Siobhan; Mehta, Alka; Vasile, Stefan; Smith, Layton H; McLean, Pamela J

    2015-05-01

    Reducing the burden of α-synuclein oligomeric species represents a promising approach for disease-modifying therapies against synucleinopathies such as Parkinson's disease and dementia with Lewy bodies. However, the lack of efficient drug discovery strategies that specifically target α-synuclein oligomers has been a limitation to drug discovery programs. Here we describe an innovative strategy that harnesses the power of bimolecular protein-fragment complementation to monitor synuclein-synuclein interactions. We have developed two robust models to monitor α-synuclein oligomerization by generating novel stable cell lines expressing α-synuclein fusion proteins for either fluorescent or bioluminescent protein-fragment complementation under the tetracycline-controlled transcriptional activation system. A pilot screen was performed resulting in the identification of two potential hits, a p38 MAPK inhibitor and a casein kinase 2 inhibitor, thereby demonstrating the suitability of our protein-fragment complementation assay for the measurement of α-synuclein oligomerization in living cells at high throughput. The application of the strategy described herein to monitor α-synuclein oligomer formation in living cells with high throughput will facilitate drug discovery efforts for disease-modifying therapies against synucleinopathies and other proteinopathies.

  7. Triptolide Promotes the Clearance of α-Synuclein by Enhancing Autophagy in Neuronal Cells.

    PubMed

    Hu, Guanzheng; Gong, Xiaoli; Wang, Le; Liu, Mengru; Liu, Yang; Fu, Xia; Wang, Wei; Zhang, Ting; Wang, Xiaomin

    2017-04-01

    Parkinson's disease (PD) is an aging-associated neurodegenerative disease with a characteristic feature of α-synuclein accumulation. Point mutations (A53T, A30P) that increase the aggregation propensity of α-synuclein result in familial early onset PD. The abnormal metabolism of α-synuclein results in aberrant level changes of α-synuclein in PD. In pathological conditions, α-synuclein is degraded mainly by the autophagy-lysosome pathway. Triptolide (T10) is a monomeric compound isolated from a traditional Chinese herb. Our group demonstrated for the first time that T10 possesses potent neuroprotective properties both in vitro and in vivo PD models. In the present study, we reported T10 as a potent autophagy inducer in neuronal cells, which helped to promote the clearance of various forms of α-synuclein in neuronal cells. We transfected neuronal cells with A53T mutant (A53T) or wild-type (WT) α-synuclein plasmids and found T10 attenuated the cytotoxicity induced by pathogenic A53T α-synuclein overexpression. We observed that T10 significantly reduced both A53T and WT α-synuclein level in neuronal cell line, as well as in primary cultured cortical neurons. Excluding the changes of syntheses, secretion, and aggregation of α-synuclein, we further added autophagy inhibitor or proteasome inhibitor with T10, and we noticed that T10 promoted the clearance of α-synuclein mainly by the autophagic pathway. Lastly, we observed increased autophagy marker LC3-II expression and autophagosomes by GFP-LC3-II accumulation and ultrastructural characterization. However, the lysosome activity and cell viability were not modulated by T10. Our study revealed that T10 could induce autophagy and promote the clearance of both WT and A53T α-synuclein in neurons. These results provide evidence of T10 as a promising mean to treat PD and other neurodegenerative diseases by reducing pathogenic proteins in neurons.

  8. Biophysical characterization of α-synuclein and its controversial structure

    PubMed Central

    Alderson, T Reid; Markley, John L

    2013-01-01

    α-synuclein, a presynaptic protein of poorly defined function, constitutes the main component of Parkinson disease-associated Lewy bodies. Extensive biophysical investigations have provided evidence that isolated α-synuclein is an intrinsically disordered protein (IDP) in vitro. Subsequently serving as a model IDP in numerous studies, α-synuclein has aided in the development of many technologies used to characterize IDPs and arguably represents the most thoroughly analyzed IDP to date. Recent reports, however, have challenged the disordered nature of α-synuclein inside cells and have instead proposed a physiologically relevant helical tetramer. Despite α-synuclein’s rich biophysical history, a single coherent picture has not yet emerged concerning its in vivo structure, dynamics, and physiological role(s). We present herein a review of the biophysical discoveries, developments, and models pertinent to the characterization of α-synuclein’s structure and analysis of the native tetramer controversy. PMID:24634806

  9. An Efficient Procedure for Removal and Inactivation of Alpha-Synuclein Assemblies from Laboratory Materials.

    PubMed

    Bousset, Luc; Brundin, Patrik; Böckmann, Anja; Meier, Beat; Melki, Ronald

    2016-01-01

    Preformed α-synuclein fibrils seed the aggregation of soluble α-synuclein in cultured cells and in vivo. This, and other findings, has kindled the idea that α-synuclein fibrils possess prion-like properties. As α-synuclein fibrils should not be considered as innocuous, there is a need for decontamination and inactivation procedures for laboratory benches and non-disposable laboratory material. We assessed the effectiveness of different procedures designed to disassemble α-synuclein fibrils and reduce their infectivity. We examined different commercially available detergents to remove α-synuclein assemblies adsorbed on materials that are not disposable and that are most found in laboratories (e.g. plastic, glass, aluminum or stainless steel surfaces). We show that methods designed to decrease PrP prion infectivity neither effectively remove α-synuclein assemblies adsorbed to different materials commonly used in the laboratory nor disassemble the fibrillar form of the protein with efficiency. In contrast, both commercial detergents and SDS detached α-synuclein assemblies from contaminated surfaces and disassembled the fibrils. We describe three cleaning procedures that effectively remove and disassemble α-synuclein seeds. The methods rely on the use of detergents that are compatible with most non-disposable tools in a laboratory. The procedures are easy to implement and significantly decrease any potential risks associated to handling α-synuclein assemblies.

  10. α-Synuclein stimulation of monoamine oxidase-B and legumain protease mediates the pathology of Parkinson's disease.

    PubMed

    Kang, Seong Su; Ahn, Eun Hee; Zhang, Zhentao; Liu, Xia; Manfredsson, Fredric P; Sandoval, Ivette M; Dhakal, Susov; Iuvone, P Michael; Cao, Xuebing; Ye, Keqiang

    2018-06-15

    Dopaminergic neurodegeneration in Parkinson's disease (PD) is associated with abnormal dopamine metabolism by MAO-B (monoamine oxidase-B) and intracellular α-Synuclein (α-Syn) aggregates, called the Lewy body. However, the molecular relationship between α-Syn and MAO-B remains unclear. Here, we show that α-Syn directly binds to MAO-B and stimulates its enzymatic activity, which triggers AEP (asparagine endopeptidase; legumain) activation and subsequent α-Syn cleavage at N103, leading to dopaminergic neurodegeneration. Interestingly, the dopamine metabolite, DOPAL, strongly activates AEP, and the N103 fragment of α-Syn binds and activates MAO-B. Accordingly, overexpression of AEP in SNCA transgenic mice elicits α-Syn N103 cleavage and accelerates PD pathogenesis, and inhibition of MAO-B by Rasagiline diminishes α-Syn-mediated PD pathology and motor dysfunction. Moreover, virally mediated expression of α-Syn N103 induces PD pathogenesis in wild-type, but not MAO-B-null mice. Our findings thus support that AEP-mediated cleavage of α-Syn at N103 is required for the association and activation of MAO-B, mediating PD pathogenesis. © 2018 The Authors.

  11. Transgenic mice overexpressing tyrosine-to-cysteine mutant human alpha-synuclein: a progressive neurodegenerative model of diffuse Lewy body disease.

    PubMed

    Zhou, Wenbo; Milder, Julie B; Freed, Curt R

    2008-04-11

    Abnormal aggregation of human alpha-synuclein in Lewy bodies and Lewy neurites is a pathological hallmark of Parkinson disease and dementia with Lewy bodies. Studies have shown that oxidation and nitration of alpha-synuclein lead to the formation of stable dimers and oligomers through dityrosine cross-linking. Previously we have reported that tyrosine-to-cysteine mutations, particularly at the tyrosine 39 residue (Y39C), significantly enhanced alpha-synuclein fibril formation and neurotoxicity. In the current study, we have generated transgenic mice expressing the Y39C mutant human alpha-synuclein gene controlled by the mouse Thy1 promoter. Mutant human alpha-synuclein was widely expressed in transgenic mouse brain, resulting in 150% overexpression relative to endogenous mouse alpha-synuclein. At age 9-12 months, transgenic mice began to display motor dysfunction in rotarod testing. Older animals aged 15-18 months showed progressive accumulation of human alpha-synuclein oligomers, associated with worse motor function and cognitive impairment in the Morris water maze. By age 21-24 months, alpha-synuclein aggregates were further increased, accompanied by severe behavioral deficits. At this age, transgenic mice developed neuropathology, such as Lewy body-like alpha-synuclein and ubiquitin-positive inclusions, phosphorylation at Ser(129) of human alpha-synuclein, and increased apoptotic cell death. In summary, Y39C human alpha-synuclein transgenic mice show age-dependent, progressive neuronal degeneration with motor and cognitive deficits similar to diffuse Lewy body disease. The time course of alpha-synuclein oligomer accumulation coincided with behavioral and pathological changes, indicating that these oligomers may initiate protein aggregation, disrupt cellular function, and eventually lead to neuronal death.

  12. Autophagy and Alpha-Synuclein: Relevance to Parkinson's Disease and Related Synucleopathies.

    PubMed

    Xilouri, Maria; Brekk, Oeystein Roed; Stefanis, Leonidas

    2016-02-01

    Evidence from human postmortem material, transgenic mice, and cellular/animal models of PD link alpha-synuclein accumulation to alterations in the autophagy lysosomal pathway. Conversely, alpha-synuclein mutations related to PD pathogenesis, as well as post-translational modifications of the wild-type protein, result in the generation of aberrant species that may impair further the function of the autophagy lysosomal pathway, thus generating a vicious cycle leading to neuronal death. Moreover, PD-linked mutations in lysosomal-related genes, such as glucocerebrosidase, have been also shown to contribute to alpha-synuclein accumulation and related toxicity, indicating that lysosomal dysfunction may, in part, account for the neurodegeneration observed in synucleinopathies. In the current review, we summarize findings related to the inter-relationship between alpha-synuclein and lysosomal proteolytic pathways, focusing especially on recent experimental strategies based on the manipulation of the autophagy lysosomal pathway to counteract alpha-synuclein-mediated neurotoxicity in vivo. Pinpointing the factors that regulate alpha-synuclein association to the lysosome may represent potential targets for therapeutic interventions in PD and related synucleinopathies. © 2016 International Parkinson and Movement Disorder Society.

  13. Structure, function and toxicity of alpha-synuclein: the Bermuda triangle in synucleinopathies.

    PubMed

    Villar-Piqué, Anna; Lopes da Fonseca, Tomás; Outeiro, Tiago Fleming

    2016-10-01

    Parkinson's disease belongs to a group of currently incurable neurodegenerative disorders characterized by the misfolding and accumulation of alpha-synuclein aggregates that are commonly known as synucleinopathies. Clinically, synucleinopathies are heterogeneous, reflecting the somewhat selective neuronal vulnerability characteristic of each disease. The precise molecular underpinnings of synucleinopathies remain unclear, but the process of aggregation of alpha-synuclein appears as a central event. However, there is still no consensus with respect to the toxic forms of alpha-synuclein, hampering our ability to use the protein as a target for therapeutic intervention. To decipher the molecular bases of synucleinopathies, it is essential to understand the complex triangle formed between the structure, function and toxicity of alpha-synuclein. Recently, important steps have been undertaken to elucidate the role of the protein in both physiological and pathological conditions. Here, we provide an overview of recent findings in the field of alpha-synuclein research, and put forward a new perspective over paradigms that persist in the field. Establishing whether alpha-synuclein has a causative role in all synucleinopathies will enable the identification of targets for the development of novel therapeutic strategies for this devastating group of disorders. Alpha-synuclein is the speculated cornerstone of several neurodegenerative disorders known as Synucleinopathies. Nevertheless, the mechanisms underlying the pathogenic effects of this protein remain unknown. Here, we review the recent findings in the three corners of alpha-synuclein biology - structure, function and toxicity - and discuss the enigmatic roads that have accompanied alpha-synuclein from the beginning. This article is part of a special issue on Parkinson disease. © 2015 International Society for Neurochemistry.

  14. A prolyl oligopeptidase inhibitor, KYP-2047, reduces α-synuclein protein levels and aggregates in cellular and animal models of Parkinson's disease

    PubMed Central

    Myöhänen, TT; Hannula, MJ; Van Elzen, R; Gerard, M; Van Der Veken, P; García-Horsman, JA; Baekelandt, V; Männistö, PT; Lambeir, AM

    2012-01-01

    BACKGROUND AND PURPOSE The aggregation of α-synuclein is connected to the pathology of Parkinson's disease and prolyl oligopeptidase (PREP) accelerates the aggregation of α-synuclein in vitro. The aim of this study was to investigate the effects of a PREP inhibitor, KYP-2047, on α-synuclein aggregation in cell lines overexpressing wild-type or A30P/A53T mutant human α-syn and in the brains of two A30P α-synuclein transgenic mouse strains. EXPERIMENTAL APPROACH Cells were exposed to oxidative stress and then incubated with the PREP inhibitor during or after the stress. Wild-type or transgenic mice were treated for 5 days with KYP-2047 (2 × 3 mg·kg−1 a day). Besides immunohistochemistry and thioflavin S staining, soluble and insoluble α-synuclein protein levels were measured by Western blot. α-synuclein mRNA levels were quantified by PCR. The colocalization of PREP and α-synuclein,and the effect of KYP-2047 on cell viability were also investigated. KEY RESULTS In cell lines, oxidative stress induced a robust aggregation of α-synuclein,and low concentrations of KYP-2047 significantly reduced the number of cells with α-synuclein inclusions while abolishing the colocalization of α-synuclein and PREP. KYP-2047 significantly reduced the amount of aggregated α-synuclein,and it had beneficial effects on cell viability. In the transgenic mice, a 5-day treatment with the PREP inhibitor reduced the amount of α-synuclein immunoreactivity and soluble α-synuclein protein in the brain. CONCLUSIONS AND IMPLICATIONS The results suggest that the PREP may play a role in brain accumulation and aggregation of α-synuclein, while KYP-2047 seems to effectively prevent these processes. PMID:22233220

  15. Recombinant α- β- and γ-Synucleins Stimulate Protein Phosphatase 2A Catalytic Subunit Activity in Cell Free Assays

    PubMed Central

    Lek, Sovanarak; Vargas-Medrano, Javier; Villanueva, Ernesto; Marcus, Brian; Godfrey, Wesley; Perez, Ruth G.

    2017-01-01

    α-Synuclein (aSyn), β-Synuclein (bSyn), and γ-Synuclein (gSyn) are members of a conserved family of chaperone-like proteins that are highly expressed in vertebrate neuronal tissues. Of the three synucleins, only aSyn has been strongly implicated in neurodegenerative disorders such as Parkinson's disease, Dementia with Lewy Bodies, and Multiple System Atrophy. In studying normal aSyn function, data indicate that aSyn stimulates the activity of the catalytic subunit of an abundantly expressed dephosphorylating enzyme, PP2Ac in vitro and in vivo. Prior data show that aSyn aggregation in human brain reduces PP2Ac activity in regions with Lewy body pathology, where soluble aSyn has become insoluble. However, because all three synucleins have considerable homology in the amino acid sequences, experiments were designed to test if all can modulate PP2Ac activity. Using recombinant synucleins and recombinant PP2Ac protein, activity was assessed by malachite green colorimetric assay. Data revealed that all three recombinant synucleins stimulated PP2Ac activity in cell-free assays, raising the possibility that the conserved homology between synucleins may endow all three homologs with the ability to bind to and activate the PP2Ac. Co-immunoprecipitation data, however, suggest that PP2Ac modulation likely occurs through endogenous interactions between aSyn and PP2Ac in vivo. PMID:28829427

  16. An Efficient Procedure for Removal and Inactivation of Alpha-Synuclein Assemblies from Laboratory Materials

    PubMed Central

    Bousset, Luc; Brundin, Patrik; Böckmann, Anja; Meier, Beat; Melki, Ronald

    2015-01-01

    Background: Preformed α-synuclein fibrils seed the aggregation of soluble α-synuclein in cultured cells and in vivo. This, and other findings, has kindled the idea that α-synuclein fibrils possess prion-like properties. Objective: As α-synuclein fibrils should not be considered as innocuous, there is a need for decontamination and inactivation procedures for laboratory benches and non-disposable laboratory material. Methods: We assessed the effectiveness of different procedures designed to disassemble α-synuclein fibrils and reduce their infectivity. We examined different commercially available detergents to remove α-synuclein assemblies adsorbed on materials that are not disposable and that are most found in laboratories (e.g. plastic, glass, aluminum or stainless steel surfaces). Results: We show that methods designed to decrease PrP prion infectivity neither effectively remove α-synuclein assemblies adsorbed to different materials commonly used in the laboratory nor disassemble the fibrillar form of the protein with efficiency. In contrast, both commercial detergents and SDS detached α-synuclein assemblies from contaminated surfaces and disassembled the fibrils. Conclusions: We describe three cleaning procedures that effectively remove and disassemble α-synuclein seeds. The methods rely on the use of detergents that are compatible with most non-disposable tools in a laboratory. The procedures are easy to implement and significantly decrease any potential risks associated to handling α-synuclein assemblies. PMID:26639448

  17. α-Synuclein Fibrils Exhibit Gain of Toxic Function, Promoting Tau Aggregation and Inhibiting Microtubule Assembly*

    PubMed Central

    Oikawa, Takayuki; Nonaka, Takashi; Terada, Makoto; Tamaoka, Akira; Hisanaga, Shin-ichi; Hasegawa, Masato

    2016-01-01

    α-Synuclein is the major component of Lewy bodies and Lewy neurites in Parkinson disease and dementia with Lewy bodies and of glial cytoplasmic inclusions in multiple system atrophy. It has been suggested that α-synuclein fibrils or intermediate protofibrils in the process of fibril formation may have a toxic effect on neuronal cells. In this study, we investigated the ability of soluble monomeric α-synuclein to promote microtubule assembly and the effects of conformational changes of α-synuclein on Tau-promoted microtubule assembly. In marked contrast to previous findings, monomeric α-synuclein had no effect on microtubule polymerization. However, both α-synuclein fibrils and protofibrils inhibited Tau-promoted microtubule assembly. The inhibitory effect of α-synuclein fibrils was greater than that of the protofibrils. Dot blot overlay assay and spin-down techniques revealed that α-synuclein fibrils bind to Tau and inhibit microtubule assembly by depleting the Tau available for microtubule polymerization. Using various deletion mutants of α-synuclein and Tau, the acidic C-terminal region of α-synuclein and the basic central region of Tau were identified as regions involved in the binding. Furthermore, introduction of α-synuclein fibrils into cultured cells overexpressing Tau protein induced Tau aggregation. These results raise the possibility that α-synuclein fibrils interact with Tau, inhibit its function to stabilize microtubules, and also promote Tau aggregation, leading to dysfunction of neuronal cells. PMID:27226637

  18. Binding Interactions of Agents That Alter α-Synuclein Aggregation

    PubMed Central

    Sivanesam, K.; Byrne, A.; Bisaglia, M.; Bubacco, L.

    2015-01-01

    Further examination of peptides with well-folded antiparallel β strands as inhibitors of amyloid formation from α-synuclein has resulted in more potent inhibitors. Several of these had multiple Tyr residues and represent a new lead for inhibitor design by small peptides that do not divert α-synuclein to non-amyloid aggregate formation. The most potent inhibitor obtained in this study is a backbone cyclized version of a previously studied β hairpin, designated as WW2, with a cross-strand Trp/Trp cluster. The cyclization was accomplished by adding a d-Pro-l-Pro turn locus across strand termini. At a 2:1 peptide to α-synuclein ratio, cyclo-WW2 displays complete inhibition of β-structure formation. Trp-bearing antiparallel β-sheets held together by a disulphide bond are also potent inhibitors. 15N HSQC spectra of α-synuclein provided new mechanistic details. The time course of 15N HSQC spectral changes observed during β-oligomer formation has revealed which segments of the structure become part of the rigid core of an oligomer at early stages of amyloidogenesis and that the C-terminus remains fully flexible throughout the process. All of the effective peptide inhibitors display binding-associated titration shifts in 15N HSQC spectra of α-synuclein in the C-terminal Q109-E137 segment. Cyclo-WW2, the most potent inhibitor, also displays titration shifts in the G41-T54 span of α-synuclein, an additional binding site. The earliest aggregation event appears to be centered about H50 which is also a binding site for our most potent inhibitor. PMID:25705374

  19. Binding Interactions of Agents That Alter α-Synuclein Aggregation.

    PubMed

    Sivanesam, K; Byrne, A; Bisaglia, M; Bubacco, L; Andersen, N

    Further examination of peptides with well-folded antiparallel β strands as inhibitors of amyloid formation from α-synuclein has resulted in more potent inhibitors. Several of these had multiple Tyr residues and represent a new lead for inhibitor design by small peptides that do not divert α-synuclein to non-amyloid aggregate formation. The most potent inhibitor obtained in this study is a backbone cyclized version of a previously studied β hairpin, designated as WW2, with a cross-strand Trp/Trp cluster. The cyclization was accomplished by adding a d-Pro-l-Pro turn locus across strand termini. At a 2:1 peptide to α-synuclein ratio, cyclo-WW2 displays complete inhibition of β-structure formation. Trp-bearing antiparallel β-sheets held together by a disulphide bond are also potent inhibitors. 15 N HSQC spectra of α-synuclein provided new mechanistic details. The time course of 15 N HSQC spectral changes observed during β-oligomer formation has revealed which segments of the structure become part of the rigid core of an oligomer at early stages of amyloidogenesis and that the C-terminus remains fully flexible throughout the process. All of the effective peptide inhibitors display binding-associated titration shifts in 15 N HSQC spectra of α-synuclein in the C-terminal Q109-E137 segment. Cyclo-WW2, the most potent inhibitor, also displays titration shifts in the G41-T54 span of α-synuclein, an additional binding site. The earliest aggregation event appears to be centered about H50 which is also a binding site for our most potent inhibitor.

  20. α-Synuclein staging in the amygdala of a Parkinson's disease model: cell types involved.

    PubMed

    Flores-Cuadrado, Alicia; Ubeda-Bañon, Isabel; Saiz-Sanchez, Daniel; de la Rosa-Prieto, Carlos; Martinez-Marcos, Alino

    2015-01-01

    Lewy bodies (ubiquitin and α-synuclein aggregates) can be detected in brain areas in a predictable sequence of six neuropathological stages in Parkinson's disease. Brainstem and olfactory structures are involved in stage 1, whereas the substantia nigra and amygdala are involved in stage 3, prior to cortical spreading. Amygdaloid pathology has been suggested to contribute to non-motor symptoms such as olfactory dysfunction and emotional impairment. This work analysed the distribution of α-synuclein at 16, 30, 43 and 56 weeks in the basolateral, central and cortical amygdaloid complexes of A53T transgenic mice. The expression of calbindin, calretinin and somatostatin was compared in control and transgenic animals. Co-localisation of these markers with α-synuclein was performed. Triple labeling of calbindin, somatostatin and α-synuclein was also investigated. Quantification was carried out using an optical dissector, ImageJ software and confocal microscopy. α-Synuclein-positive cells were mainly concentrated in the basolateral and cortical amygdaloid complexes with a non-significant increase over time from 16 to 30-43 weeks and a significant decrease thereafter. The expression of interneuron markers showed a significant decrease with aging in control animals. When comparing these markers between control and transgenic mice, calretinin was moderately decreased, but calbindin and somatostatin were highly reduced, particularly in the cortical amygdaloid complex. α-Synuclein mostly co-localised with calbindin and a number of these cells also co-expressed somatostatin. These data on α-synucleinopathy staging in the amygdala could help to explain non-motor symptoms as well as to understand the progression of Parkinson's disease in the brain. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  1. Age-dependent α-synuclein aggregation in the Microcebus murinus lemur primate

    PubMed Central

    Canron, Marie-Hélène; Perret, Martine; Vital, Anne; Bézard, Erwan; Dehay, Benjamin

    2012-01-01

    Since age-dependent deposition of Aβ-amyloid has been reported in the Microcebus murinus, we posited that this animal could as well be a model of age-related synucleinopathy. We characterized the distribution of Aβ-amyloid, α-synuclein and two of its modified forms in the brain of Microcebus murinus aged from 1.5 to 10 years. Intracytoplasmic α-synuclein aggregates were observed only in aged animals in different brain regions, which were also phospho-Ser129 and nitrated α-synuclein immunoreactive. Age-dependent α-synuclein aggregation occurs spontaneously in mouse lemur primates. Microcebus murinus may provide a model to study age-associated α-synucleinopathy and for testing putative therapeutic interventions for both Alzheimer's and Parkinson's diseases. PMID:23205271

  2. Interaction of α-synuclein with Rhus typhina tannin - Implication for Parkinson's disease.

    PubMed

    Sekowski, Szymon; Ionov, Maksim; Abdulladjanova, Nodira; Makhmudov, Rustam; Mavlyanov, Saidmukhtar; Milowska, Katarzyna; Bryszewska, Maria; Zamaraeva, Maria

    2017-07-01

    The etiology of Parkinson's disease (PD) relates to α-synuclein, a small protein with the ability to aggregate and form Lewy bodies. One of its prevention strategies is inhibition of α-synuclein oligomerization. We have investigated the interaction of α-synuclein and human serum albumin with 3,6-bis-О-di-О-galloyl-1,2,4-tri-О-galloyl-β-d-glucose (a tannin isolated from the plant Rhus typhina). Using fluorescence spectroscopy method we found that this tannin interacts strongly with α-synuclein forming complexes. Circular dichroism analysis showed a time-dependent inhibition of α-synuclein aggregation in the presence of the tannin. On the other hand, 3,6-bis-О-di-О-galloyl-1,2,4-tri-О-galloyl-β-d-glucose had a much stronger interaction with human serum albumin than α-synuclein. The calculated binding constant for tannin-protein interaction was considerably higher for albumin than α-synuclein. This tannin interacted with albumin through a "sphere of action" mechanism. The results lead to the conclusion that 3,6-bis-О-di-О-galloyl-1,2,4-tri-О-galloyl-β-d-glucose is a potent preventive compound against Parkinson's disease. However, this tannin interacts very strongly with human serum albumin, significantly reducing the bioavailability of this compound. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. PA700, the regulatory complex of the 26S proteasome, interferes with alpha-synuclein assembly.

    PubMed

    Ghee, Medeva; Melki, Ronald; Michot, Nadine; Mallet, Jacques

    2005-08-01

    Parkinson's disease is characterized by the loss of dopaminergic neurons in the nigrostriatal pathway accompanied by the presence of intracellular cytoplasmic inclusions, termed Lewy bodies. Fibrillized alpha-synuclein forms the major component of Lewy bodies. We reported a specific interaction between rat alpha-synuclein and tat binding protein 1, a subunit of PA700, the regulatory complex of the 26S proteasome. It has been demonstrated that PA700 prevents the aggregation of misfolded, nonubiquinated substrates. In this study, we examine the effect of PA700 on the aggregation of wild-type and A53T mutant alpha-synuclein. PA700 inhibits both wild-type and A53T alpha-synuclein fibril formation as measured by Thioflavin T fluorescence. Using size exclusion chromatography, we present evidence for a stable PA700-alpha-synuclein complex. Sedimentation analyses reveal that PA700 sequesters alpha-synuclein in an assembly incompetent form. Analysis of the morphology of wild-type and A53T alpha-synuclein aggregates during the course of fibrillization by electron microscopy demonstrate the formation of amyloid-like fibrils. Secondary structure analyses of wild-type and A53T alpha-synuclein assembled in the presence of PA700 revealed a decrease in the overall amount of assembled alpha-synuclein with no significant change in protein conformation. Thus, PA700 acts on alpha-synuclein assembly and not on the structure of fibrils. We hypothesize that PA700 sequesters alpha-synuclein oligomeric species that are the precursors of the fibrillar form of the protein, thus preventing its assembly into fibrils.

  4. Dopamine Manipulation Affects Response Vigor Independently of Opportunity Cost.

    PubMed

    Zénon, Alexandre; Devesse, Sophie; Olivier, Etienne

    2016-09-14

    Dopamine is known to be involved in regulating effort investment in relation to reward, and the disruption of this mechanism is thought to be central in some pathological situations such as Parkinson's disease, addiction, and depression. According to an influential model, dopamine plays this role by encoding the opportunity cost, i.e., the average value of forfeited actions, which is an important parameter to take into account when making decisions about which action to undertake and how fast to execute it. We tested this hypothesis by asking healthy human participants to perform two effort-based decision-making tasks, following either placebo or levodopa intake in a double blind within-subject protocol. In the effort-constrained task, there was a trade-off between the amount of force exerted and the time spent in executing the task, such that investing more effort decreased the opportunity cost. In the time-constrained task, the effort duration was constant, but exerting more force allowed the subject to earn more substantial reward instead of saving time. Contrary to the model predictions, we found that levodopa caused an increase in the force exerted only in the time-constrained task, in which there was no trade-off between effort and opportunity cost. In addition, a computational model showed that dopamine manipulation left the opportunity cost factor unaffected but altered the ratio between the effort cost and reinforcement value. These findings suggest that dopamine does not represent the opportunity cost but rather modulates how much effort a given reward is worth. Dopamine has been proposed in a prevalent theory to signal the average reward rate, used to estimate the cost of investing time in an action, also referred to as opportunity cost. We contrasted the effect of dopamine manipulation in healthy participants in two tasks, in which increasing response vigor (i.e., the amount of effort invested in an action) allowed either to save time or to earn more

  5. Nutrition and dopamine: An intake of tyrosine in royal jelly can affect the brain levels of dopamine in male honeybees (Apis mellifera L.).

    PubMed

    Sasaki, Ken

    2016-04-01

    Precursors of neuroactive substances can be obtained from dietary sources, which can affect the resulting production of such substances in the brain. In social species, an intake of the precursor in food could be controlled by social interactions. To test the effects of dietary tyrosine on the brain dopamine levels in social insect colonies, male and worker honeybees were fed tyrosine or royal jelly under experimental conditions and the brain levels of dopamine and its metabolite were then measured. The results showed that the levels of dopamine and its metabolite in the brains of 4- and 8-day-old workers and 8-day-old males were significantly higher in tyrosine-fed bees than in control bees, but the levels in 4-day-old males were not. The brain levels of dopamine and its metabolite in 4- and 8-day-old males and workers were significantly higher in royal jelly-fed bees than in control bees, except for one group of 4-day-old workers. Food exchanges with workers were observed in males during 1-3 days, but self-feedings were also during 5-7 days. These results suggest that the brain levels of dopamine in males can be controlled by an intake of tyrosine in food via exchanging food with nestmates and by self-feeding. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. One single method to produce native and Tat-fused recombinant human α-synuclein in Escherichia coli.

    PubMed

    Caldinelli, Laura; Albani, Diego; Pollegioni, Loredano

    2013-04-04

    Human α-synuclein is a small-sized, natively unfolded protein that in fibrillar form is the primary component of Lewy bodies, the pathological hallmark of Parkinson's disease. Experimental evidence suggests that α-synuclein aggregation is the key event that triggers neurotoxicity although additional findings have proposed a protective role of α-synuclein against oxidative stress. One way to address the mechanism of this protective action is to evaluate α-synuclein-mediated protection by delivering this protein inside cells using a chimeric protein fused with the Tat-transduction domain of HIV Tat, named TAT-α-synuclein. A reliable protocol was designed to efficiently express and purify two different forms of human α-synuclein. The synthetic cDNAs encoding for the native α-synuclein and the fusion protein with the transduction domain of Tat protein from HIV were overexpressed in a BL21(DE3) E. coli strain as His-tagged proteins. The recombinant proteins largely localized (≥ 85%) to the periplasmic space. By using a quick purification protocol, based on recovery of periplasmic space content and metal-chelating chromatography, the recombinant α-synuclein protein forms could be purified in a single step to ≥ 95% purity. Both α-synuclein recombinant proteins form fibrils and the TAT-α-synuclein is also cytotoxic in the micromolar concentration range. To further characterize the molecular mechanisms of α-synuclein neurotoxicity both in vitro and in vivo and to evaluate the relevance of extracellular α-synuclein for the pathogenesis and progression of Parkinson's disease, a suitable method to produce different high-quality forms of this pathological protein is required. Our optimized expression and purification procedure offers an easier and faster means of producing different forms (i.e., both the native and the TAT-fusion form) of soluble recombinant α-synuclein than previously described procedures.

  7. Targeting α-synuclein for treating Parkinson’s disease: mechanistic and therapeutic considerations

    PubMed Central

    Gorry, Philippe; Przedborski, Serge; Vila, Miquel; Hunot, Stephane; Singleton, Andrew; Olanow, C. Warren; Merchant, Kalpana M.; Bezard, Erwan; Petsko, Gregory A.; Meissner, Wassilios G.

    2016-01-01

    Summary Progressive neuronal cell loss in a small subset of brainstem and mesencephalic nuclei and widespread aggregation of the α-synuclein protein in the form of Lewy bodies and Lewy neurites are neuropathological hallmarks of Parkinson’s disease. Most cases occur sporadically, but mutations in several genes, including α-synuclein, are associated with disease development. The mechanisms driving neurodegeneration remain unknown, hence limiting therapeutic strategies aimed at blocking neuronal death. This review describes current evidence for a predominant role of α-synuclein in the pathogenesis of PD, as well as some of the most promising α-synuclein-based strategies currently in development for this incurable neurodegenerative disorder. PMID:26050140

  8. α-Synuclein inclusions in the skin of Parkinson's disease and parkinsonism.

    PubMed

    Rodríguez-Leyva, Ildefonso; Calderón-Garcidueñas, Ana Laura; Jiménez-Capdeville, María E; Rentería-Palomo, Ana Arely; Hernandez-Rodriguez, Héctor Gerardo; Valdés-Rodríguez, Rodrigo; Fuentes-Ahumada, Cornelia; Torres-Álvarez, Bertha; Sepúlveda-Saavedra, Julio; Soto-Domínguez, Adolfo; Santoyo, Martha E; Rodriguez-Moreno, José Ildefonso; Castanedo-Cázares, Juan Pablo

    2014-07-01

    The presence in the brain of α-synuclein containing Lewy neurites, or bodies, is the histological hallmark of Parkinson's disease (PD). The discovery of α-synuclein aggregates in nerve endings of the heart, digestive tract, and skin has lent support to the concept of PD as a systemic disease. Our goals were, first, to demonstrate the presence of α-synuclein inclusions in the skin and, second, to detect quantitative differences between patients with PD and atypical parkinsonism (AP). Skin biopsies were taken from 67 patients and 20 controls. The biopsies underwent immunohistochemistry (IHC) and immunofluorescence (IF) testing for α-synuclein, whereupon its presence was quantified as the percentage of positive cells. Patients were divided into those with PD and those with AP. AP patients included AP with neurodegenerative disease (proteinopathies) and secondary AP. Sixty-seven patients (34 with PD) and 20 controls were recruited. In the PD group, α-synuclein was detected in 58% of the cells in the spinous cell layer (SCL), 62% in the pilosebaceous unit (PSU), and 58% in the eccrine glands (EG). The AP-proteinopathies group showed 7%, 7%, and 0% expression of α-synuclein, respectively. No expression was found in the skin of the control group. The expression of α-synuclein in the skin was relatively high in the PD group, scarce in AP, and null for the individuals in the control group. While these findings require further confirmation, this minimally invasive technique may aid in the improvement of the accuracy of PD diagnoses.

  9. Direct Membrane Association Drives Mitochondrial Fission by the Parkinson Disease-associated Protein α-Synuclein*♦

    PubMed Central

    Nakamura, Ken; Nemani, Venu M.; Azarbal, Farnaz; Skibinski, Gaia; Levy, Jon M.; Egami, Kiyoshi; Munishkina, Larissa; Zhang, Jue; Gardner, Brooke; Wakabayashi, Junko; Sesaki, Hiromi; Cheng, Yifan; Finkbeiner, Steven; Nussbaum, Robert L.; Masliah, Eliezer; Edwards, Robert H.

    2011-01-01

    The protein α-synuclein has a central role in Parkinson disease, but the mechanism by which it contributes to neural degeneration remains unknown. We now show that the expression of α-synuclein in mammalian cells, including neurons in vitro and in vivo, causes the fragmentation of mitochondria. The effect is specific for synuclein, with more fragmentation by α- than β- or γ-isoforms, and it is not accompanied by changes in the morphology of other organelles or in mitochondrial membrane potential. However, mitochondrial fragmentation is eventually followed by a decline in respiration and neuronal death. The fragmentation does not require the mitochondrial fission protein Drp1 and involves a direct interaction of synuclein with mitochondrial membranes. In vitro, synuclein fragments artificial membranes containing the mitochondrial lipid cardiolipin, and this effect is specific for the small oligomeric forms of synuclein. α-Synuclein thus exerts a primary and direct effect on the morphology of an organelle long implicated in the pathogenesis of Parkinson disease. PMID:21489994

  10. Reduced glucocerebrosidase is associated with increased α-synuclein in sporadic Parkinson's disease.

    PubMed

    Murphy, Karen E; Gysbers, Amanda M; Abbott, Sarah K; Tayebi, Nahid; Kim, Woojin S; Sidransky, Ellen; Cooper, Antony; Garner, Brett; Halliday, Glenda M

    2014-03-01

    Heterozygous mutations in GBA1, the gene encoding lysosomal glucocerebrosidase, are the most frequent known genetic risk factor for Parkinson's disease. Reduced glucocerebrosidase and α-synuclein accumulation are directly related in cell models of Parkinson's disease. We investigated relationships between Parkinson's disease-specific glucocerebrosidase deficits, glucocerebrosidase-related pathways, and α-synuclein levels in brain tissue from subjects with sporadic Parkinson's disease without GBA1 mutations. Brain regions with and without a Parkinson's disease-related increase in α-synuclein levels were assessed in autopsy samples from subjects with sporadic Parkinson's disease (n = 19) and age- and post-mortem delay-matched controls (n = 10). Levels of glucocerebrosidase, α-synuclein and related lysosomal and autophagic proteins were assessed by western blotting. Glucocerebrosidase enzyme activity was measured using a fluorimetric assay, and glucocerebrosidase and α-synuclein messenger RNA expression determined by quantitative polymerase chain reaction. Related sphingolipids were analysed by mass spectrometry. Multivariate statistical analyses were performed to identify differences between disease groups and regions, with non-parametric correlations used to identify relationships between variables. Glucocerebrosidase protein levels and enzyme activity were selectively reduced in the early stages of Parkinson's disease in regions with increased α-synuclein levels although limited inclusion formation, whereas GBA1 messenger RNA expression was non-selectively reduced in Parkinson's disease. The selective loss of lysosomal glucocerebrosidase was directly related to reduced lysosomal chaperone-mediated autophagy, increased α-synuclein and decreased ceramide. Glucocerebrosidase deficits in sporadic Parkinson's disease are related to the abnormal accumulation of α-synuclein and are associated with substantial alterations in lysosomal chaperone-mediated autophagy

  11. Familial knockin mutation of LRRK2 causes lysosomal dysfunction and accumulation of endogenous insoluble α-synuclein in neurons.

    PubMed

    Schapansky, Jason; Khasnavis, Saurabh; DeAndrade, Mark P; Nardozzi, Jonathan D; Falkson, Samuel R; Boyd, Justin D; Sanderson, John B; Bartels, Tim; Melrose, Heather L; LaVoie, Matthew J

    2018-03-01

    Missense mutations in the multi-domain kinase LRRK2 cause late onset familial Parkinson's disease. They most commonly with classic proteinopathy in the form of Lewy bodies and Lewy neurites comprised of insoluble α-synuclein, but in rare cases can also manifest tauopathy. The normal function of LRRK2 has remained elusive, as have the cellular consequences of its mutation. Data from LRRK2 null model organisms and LRRK2-inhibitor treated animals support a physiological role for LRRK2 in regulating lysosome function. Since idiopathic and LRRK2-linked PD are associated with the intraneuronal accumulation of protein aggregates, a series of critical questions emerge. First, how do pathogenic mutations that increase LRRK2 kinase activity affect lysosome biology in neurons? Second, are mutation-induced changes in lysosome function sufficient to alter the metabolism of α-synuclein? Lastly, are changes caused by pathogenic mutation sensitive to reversal with LRRK2 kinase inhibitors? Here, we report that mutation of LRRK2 induces modest but significant changes in lysosomal morphology and acidification, and decreased basal autophagic flux when compared to WT neurons. These changes were associated with an accumulation of detergent-insoluble α-synuclein and increased neuronal release of α-synuclein and were reversed by pharmacologic inhibition of LRRK2 kinase activity. These data demonstrate a critical and disease-relevant influence of native neuronal LRRK2 kinase activity on lysosome function and α-synuclein homeostasis. Furthermore, they also suggest that lysosome dysfunction, altered neuronal α-synuclein metabolism, and the insidious accumulation of aggregated protein over decades may contribute to pathogenesis in this late-onset form of familial PD. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Alpha-Synuclein Produces Early Behavioral Alterations via Striatal Cholinergic Synaptic Dysfunction by Interacting With GluN2D N-Methyl-D-Aspartate Receptor Subunit.

    PubMed

    Tozzi, Alessandro; de Iure, Antonio; Bagetta, Vincenza; Tantucci, Michela; Durante, Valentina; Quiroga-Varela, Ana; Costa, Cinzia; Di Filippo, Massimiliano; Ghiglieri, Veronica; Latagliata, Emanuele Claudio; Wegrzynowicz, Michal; Decressac, Mickael; Giampà, Carmela; Dalley, Jeffrey W; Xia, Jing; Gardoni, Fabrizio; Mellone, Manuela; El-Agnaf, Omar Mukhtar; Ardah, Mustafa Taleb; Puglisi-Allegra, Stefano; Björklund, Anders; Spillantini, Maria Grazia; Picconi, Barbara; Calabresi, Paolo

    2016-03-01

    Advanced Parkinson's disease (PD) is characterized by massive degeneration of nigral dopaminergic neurons, dramatic motor and cognitive alterations, and presence of nigral Lewy bodies, whose main constituent is α-synuclein (α-syn). However, the synaptic mechanisms underlying behavioral and motor effects induced by early selective overexpression of nigral α-syn are still a matter of debate. We performed behavioral, molecular, and immunohistochemical analyses in two transgenic models of PD, mice transgenic for truncated human α-synuclein 1-120 and rats injected with the adeno-associated viral vector carrying wild-type human α-synuclein. We also investigated striatal synaptic plasticity by electrophysiological recordings from spiny projection neurons and cholinergic interneurons. We found that overexpression of truncated or wild-type human α-syn causes partial reduction of striatal dopamine levels and selectively blocks the induction of long-term potentiation in striatal cholinergic interneurons, producing early memory and motor alterations. These effects were dependent on α-syn modulation of the GluN2D-expressing N-methyl-D-aspartate receptors in cholinergic interneurons. Acute in vitro application of human α-syn oligomers mimicked the synaptic effects observed ex vivo in PD models. We suggest that striatal cholinergic dysfunction, induced by a direct interaction between α-syn and GluN2D-expressing N-methyl-D-aspartate receptors, represents a precocious biological marker of the disease. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  13. The chaperonin CCT inhibits assembly of α-synuclein amyloid fibrils by a specific, conformation-dependent interaction

    PubMed Central

    Sot, Begoña; Rubio-Muñoz, Alejandra; Leal-Quintero, Ahudrey; Martínez-Sabando, Javier; Marcilla, Miguel; Roodveldt, Cintia; Valpuesta, José M.

    2017-01-01

    The eukaryotic chaperonin CCT (chaperonin containing TCP-1) uses cavities built into its double-ring structure to encapsulate and to assist folding of a large subset of proteins. CCT can inhibit amyloid fibre assembly and toxicity of the polyQ extended mutant of huntingtin, the protein responsible for Huntington’s disease. This raises the possibility that CCT modulates other amyloidopathies, a still-unaddressed question. We show here that CCT inhibits amyloid fibre assembly of α-synuclein A53T, one of the mutants responsible for Parkinson’s disease. We evaluated fibrillation blockade in α-synuclein A53T deletion mutants and CCT interactions of full-length A53T in distinct oligomeric states to define an inhibition mechanism specific for α-synuclein. CCT interferes with fibre assembly by interaction of its CCTζ and CCTγ subunits with the A53T central hydrophobic region (NAC). This interaction is specific to NAC conformation, as it is produced once soluble α-synuclein A53T oligomers form and blocks the reaction before fibres begin to grow. Finally, we show that this association inhibits α-synuclein A53T oligomer toxicity in neuroblastoma cells. In summary, our results and those for huntingtin suggest that CCT is a general modulator of amyloidogenesis via a specific mechanism. PMID:28102321

  14. Interaction of Synuclein and Inflammation in Dopaminergic Neurodegeneration

    DTIC Science & Technology

    2014-06-01

    are less responsive to the blocking effects of anti-CD36 antibodies. The CD36 inhibitor, ursolic acid , at concentrations of 10-5 and 10-6, reduced...N9 chemotaxis across native synuclein by almost 50%. Equally interesting is the fact that ursolic acid had a small effect on CD36-deficient N9 cell...chemotaxis across synuclein which suggests that ursolic acid may also inhibit other scavenger receptors such as SR1 and RAGE. Ursolic acid was

  15. Structural and functional characterization of two alpha-synuclein strains

    NASA Astrophysics Data System (ADS)

    Bousset, Luc; Pieri, Laura; Ruiz-Arlandis, Gemma; Gath, Julia; Jensen, Poul Henning; Habenstein, Birgit; Madiona, Karine; Olieric, Vincent; Böckmann, Anja; Meier, Beat H.; Melki, Ronald

    2013-10-01

    α-synuclein aggregation is implicated in a variety of diseases including Parkinson’s disease, dementia with Lewy bodies, pure autonomic failure and multiple system atrophy. The association of protein aggregates made of a single protein with a variety of clinical phenotypes has been explained for prion diseases by the existence of different strains that propagate through the infection pathway. Here we structurally and functionally characterize two polymorphs of α-synuclein. We present evidence that the two forms indeed fulfil the molecular criteria to be identified as two strains of α-synuclein. Specifically, we show that the two strains have different structures, levels of toxicity, and in vitro and in vivo seeding and propagation properties. Such strain differences may account for differences in disease progression in different individuals/cell types and/or types of synucleinopathies.

  16. α-Synuclein Sequesters Dnmt1 from the Nucleus

    PubMed Central

    Desplats, Paula; Spencer, Brian; Coffee, Elizabeth; Patel, Pruthul; Michael, Sarah; Patrick, Christina; Adame, Anthony; Rockenstein, Edward; Masliah, Eliezer

    2011-01-01

    DNA methylation is a major epigenetic modification that regulates gene expression. Dnmt1, the maintenance DNA methylation enzyme, is abundantly expressed in the adult brain and is mainly located in the nuclear compartment, where it has access to chromatin. Hypomethylation of CpG islands at intron 1 of the SNCA gene has recently been reported to result in overexpression of α-synuclein in Parkinson disease (PD) and related disorders. We therefore investigated the mechanisms underlying altered DNA methylation in PD and dementia with Lewy bodies (DLB). We present evidence of reduction of nuclear Dnmt1 levels in human postmortem brain samples from PD and DLB patients as well as in the brains of α-synuclein transgenic mice models. Furthermore, sequestration of Dnmt1 in the cytoplasm results in global DNA hypomethylation in human and mouse brains, involving CpG islands upstream of SNCA, SEPW1, and PRKAR2A genes. We report that association of Dnmt1 and α-synuclein might mediate aberrant subcellular localization of Dnmt1. Nuclear Dnmt1 levels were partially rescued by overexpression of Dnmt1 in neuronal cell cultures and in α-synuclein transgenic mice brains. Our results underscore a novel mechanism for epigenetic dysregulation in Lewy body diseases, which might underlie the decrease in DNA methylation reported for PD and DLB. PMID:21296890

  17. Locomotor differences in mice expressing wild-type human α-synuclein.

    PubMed

    Giraldo, Genesys; Brooks, Mieu; Giasson, Benoit I; Janus, Christopher

    2018-05-01

    Parkinson's disease manifests as a progressive movement disorder with underlying degeneration of dopaminergic neurons in the substantia nigra, consequent depletion of dopamine levels, and the accumulation of Lewy bodies in the brain. Because α-synuclein (α-Syn) protein is the major component of Lewy bodies, mouse models expressing wild-type or mutant SNCA/α-Syn genes provide a useful tool to investigate canonical characteristics of the disease. We evaluated a mouse model (denoted M20) that expresses human wild-type SNCA gene. The M20 mice showed abnormal locomotor behavior and reduced species-specific home cage activity. However, the direction of behavioral changes was task specific. In comparison with their control littermates, the M20 mice exhibited shorter grip endurance, and longer times to traverse elevated beams, but they descended the vertical pole faster and stayed longer on the accelerated rod than the control mice. The M20 mice were also impaired in burrowing and nest building activities. These results indicate a possible role of α-Syn in motor coordination and the motivation to perform species-specific behaviors in the presymptomatic model of synucleinopathy. Published by Elsevier Inc.

  18. Gamma Synuclein Promotes a Metastatic Phenotype in Breast and Ovarian Tumor Cells by Modulating the Rho Signal Transduction Activity

    DTIC Science & Technology

    2002-05-01

    peripheral nervous system, such as dorsal root ganglia and trigeminal ganglia . Synoretin, the newest member of the synuclein family is expressed at high...involved in neuron development and function (43). The involvement of y-synuclein in human neoplastic diseases came to light when y-synuclein was...wed) are a famnily of small, highly conserved proteins exprssed predominanly in neurons . While a- synfucein is impicatad i neurodegenerative diseases

  19. Alpha-Synuclein Expression Restricts RNA Viral Infections in the Brain.

    PubMed

    Beatman, Erica L; Massey, Aaron; Shives, Katherine D; Burrack, Kristina S; Chamanian, Mastooreh; Morrison, Thomas E; Beckham, J David

    2015-12-30

    We have discovered that native, neuronal expression of alpha-synuclein (Asyn) inhibits viral infection, injury, and disease in the central nervous system (CNS). Enveloped RNA viruses, such as West Nile virus (WNV), invade the CNS and cause encephalitis, yet little is known about the innate neuron-specific inhibitors of viral infections in the CNS. Following WNV infection of primary neurons, we found that Asyn protein expression is increased. The infectious titer of WNV and Venezuelan equine encephalitis virus (VEEV) TC83 in the brains of Asyn-knockout mice exhibited a mean increase of 10(4.5) infectious viral particles compared to the titers in wild-type and heterozygote littermates. Asyn-knockout mice also exhibited significantly increased virus-induced mortality compared to Asyn heterozygote or homozygote control mice. Virus-induced Asyn localized to perinuclear, neuronal regions expressing viral envelope protein and the endoplasmic reticulum (ER)-associated trafficking protein Rab1. In Asyn-knockout primary neuronal cultures, the levels of expression of ER signaling pathways, known to support WNV replication, were significantly elevated before and during viral infection compared to those in Asyn-expressing primary neuronal cultures. We propose a model in which virus-induced Asyn localizes to ER-derived membranes, modulates virus-induced ER stress signaling, and inhibits viral replication, growth, and injury in the CNS. These data provide a novel and important functional role for the expression of native alpha-synuclein, a protein that is closely associated with the development of Parkinson's disease. Neuroinvasive viruses such as West Nile virus are able to infect neurons and cause severe disease, such as encephalitis, or infection of brain tissue. Following viral infection in the central nervous system, only select neurons are infected, implying that neurons exhibit innate resistance to viral infections. We discovered that native neuronal expression of alpha-synuclein

  20. Structural and functional characterization of two alpha-synuclein strains

    PubMed Central

    Bousset, Luc; Pieri, Laura; Ruiz-Arlandis, Gemma; Gath, Julia; Jensen, Poul Henning; Habenstein, Birgit; Madiona, Karine; Olieric, Vincent; Böckmann, Anja; Meier, Beat H.; Melki, Ronald

    2013-01-01

    α-synuclein aggregation is implicated in a variety of diseases including Parkinson’s disease, dementia with Lewy bodies, pure autonomic failure and multiple system atrophy. The association of protein aggregates made of a single protein with a variety of clinical phenotypes has been explained for prion diseases by the existence of different strains that propagate through the infection pathway. Here we structurally and functionally characterize two polymorphs of α-synuclein. We present evidence that the two forms indeed fulfil the molecular criteria to be identified as two strains of α-synuclein. Specifically, we show that the two strains have different structures, levels of toxicity, and in vitro and in vivo seeding and propagation properties. Such strain differences may account for differences in disease progression in different individuals/cell types and/or types of synucleinopathies. PMID:24108358

  1. Structure of the toxic core of α-synuclein from invisible crystals

    DOE PAGES

    Rodriguez, Jose A.; Ivanova, Magdalena I.; Sawaya, Michael R.; ...

    2015-09-09

    We report that the protein α-synuclein is the main component of Lewy bodies, the neuron-associated aggregates seen in Parkinson disease and other neurodegenerative pathologies. An 11-residue segment, which we term NACore, appears to be responsible for amyloid formation and cytotoxicity of human α-synuclein. Here we describe crystals of NACore that have dimensions smaller than the wavelength of visible light and thus are invisible by optical microscopy. As the crystals are thousands of times too small for structure determination by synchrotron X-ray diffraction, we use micro-electron diffraction to determine the structure at atomic resolution. The 1.4 Å resolution structure demonstrates thatmore » this method can determine previously unknown protein structures and here yields, to our knowledge, the highest resolution achieved by any cryo-electron microscopy method to date. The structure exhibits protofibrils built of pairs of face-to-face β-sheets. X-ray fibre diffraction patterns show the similarity of NACore to toxic fibrils of full-length α-synuclein. Finally, the NACore structure, together with that of a second segment, inspires a model for most of the ordered portion of the toxic, full-length α-synuclein fibril, presenting opportunities for the design of inhibitors of α-synuclein fibrils.« less

  2. Quantitative proteomics in A30P*A53T α-synuclein transgenic mice reveals upregulation of Sel1l.

    PubMed

    Yan, Jianguo; Zhang, Pei; Jiao, Fengjuan; Wang, Qingzhi; He, Feng; Zhang, Qian; Zhang, Zheng; Lv, Zexi; Peng, Xiang; Cai, Hongwei; Tian, Bo

    2017-01-01

    α-Synuclein is an abundantly expressed neuronal protein that is at the center of focus in understanding a group of neurodegenerative disorders called synucleinopathies, which are characterized by the intracellular presence of aggregated α-synuclein. However, the mechanism of α-synuclein biology in synucleinopathies pathogenesis is not fully understood. In this study, mice overexpressing human A30P*A53T α-synuclein were evaluated by a motor behavior test and count of TH-positive neurons, and then two-dimensional liquid chromatography-tandem mass spectrometry coupled with tandem mass tags (TMTs) labeling was employed to quantitatively identify the differentially expressed proteins of substantia nigra pars compacta (SNpc) tissue samples that were obtained from the α-synuclein transgenic mice and wild type controls. The number of SNpc dopaminergic neurons and the motor behavior were unchanged in A30P*A53T transgenic mice at the age of 6 months. Of the 4,715 proteins identified by proteomic techniques, 271 were differentially expressed, including 249 upregulated and 22 downregulated proteins. These alterations were primarily associated with mitochondrial dysfunction, oxidative stress, ubiquitin-proteasome system impairment, and endoplasmic reticulum (ER) stress. Some obviously changed proteins, which were validated by western blotting and immunofluorescence staining, including Sel1l and Sdhc, may be involved in the α-synuclein pathologies of synucleinopathies. A biological pathway analysis of common related proteins showed that the proteins were linked to a total of 31 KEGG pathways. Our findings suggest that these identified proteins may serve as novel therapeutic targets for synucleinopathies.

  3. Increased lipolysis and altered lipid homeostasis protect y-synuclein null mutant mice from diet-induced obesity

    USDA-ARS?s Scientific Manuscript database

    Synucleins are a family of homologous proteins principally known for their involvement in neurodegeneration. In neurons a-synuclein promotes assembly of SNARE complexes required for fusion of synaptic vesicles with the plasma membrane during neurotransmitter release. Y-synuclein is highly expressed ...

  4. KLK6 proteolysis is implicated in the turnover and uptake of extracellular alpha-synuclein species.

    PubMed

    Pampalakis, Georgios; Sykioti, Vasia-Samantha; Ximerakis, Methodios; Stefanakou-Kalakou, Ioanna; Melki, Ronald; Vekrellis, Kostas; Sotiropoulou, Georgia

    2017-02-28

    KLK6 is a serine protease highly expressed in the nervous system. In synucleinopathies, including Parkinson disease, the levels of KLK6 inversely correlate with α-synuclein in CSF. Recently, we suggested that recombinant KLK6 mediates the degradation of extracellular α-synuclein directly and via a proteolytic cascade that involves unidentified metalloproteinase(s). Here, we show that recombinant and naturally secreted KLK6 can readily cleave α-synuclein fibrils that have the potential for cell-to-cell propagation in "a prion-like mechanism". Importantly, KLK6-deficient primary cortical neurons have increased ability for α-synuclein fibril uptake. We also demonstrate that KLK6 activates proMMP2, which in turn can cleave α-synuclein. The repertoire of proteases activated by KLK6 in a neuronal environment was analyzed by degradomic profiling, which also identified ADAMTS19 and showed that KLK6 has a limited number of substrates indicating specific biological functions such as the regulation of α-synuclein turnover. We generated adenoviral vectors for KLK6 delivery and demonstrated that the levels of extracellular α-synuclein can be reduced by neuronally secreted KLK6. Our findings open the possibility to exploit KLK6 as a novel therapeutic target for Parkinson disease and other synucleinopathies.

  5. KLK6 proteolysis is implicated in the turnover and uptake of extracellular alpha-synuclein species

    PubMed Central

    Pampalakis, Georgios; Sykioti, Vasia-Samantha; Ximerakis, Methodios; Stefanakou-Kalakou, Ioanna; Melki, Ronald; Vekrellis, Kostas; Sotiropoulou, Georgia

    2017-01-01

    KLK6 is a serine protease highly expressed in the nervous system. In synucleinopathies, including Parkinson disease, the levels of KLK6 inversely correlate with α-synuclein in CSF. Recently, we suggested that recombinant KLK6 mediates the degradation of extracellular α-synuclein directly and via a proteolytic cascade that involves unidentified metalloproteinase(s). Here, we show that recombinant and naturally secreted KLK6 can readily cleave α-synuclein fibrils that have the potential for cell-to-cell propagation in “a prion-like mechanism”. Importantly, KLK6-deficient primary cortical neurons have increased ability for α-synuclein fibril uptake. We also demonstrate that KLK6 activates proMMP2, which in turn can cleave α-synuclein. The repertoire of proteases activated by KLK6 in a neuronal environment was analyzed by degradomic profiling, which also identified ADAMTS19 and showed that KLK6 has a limited number of substrates indicating specific biological functions such as the regulation of α-synuclein turnover. We generated adenoviral vectors for KLK6 delivery and demonstrated that the levels of extracellular α-synuclein can be reduced by neuronally secreted KLK6. Our findings open the possibility to exploit KLK6 as a novel therapeutic target for Parkinson disease and other synucleinopathies. PMID:27845893

  6. Neuroprotective effects of voluntary running on cognitive dysfunction in an α-synuclein rat model of Parkinson's disease.

    PubMed

    Crowley, Erin K; Nolan, Yvonne M; Sullivan, Aideen M

    2018-05-01

    Parkinson's disease (PD) is no longer primarily classified as a motor disorder due to increasing recognition of the impact on patients of several nonmotor PD symptoms, including cognitive dysfunction. These nonmotor symptoms are highly prevalent and greatly affect the quality of life of patients with PD, and so, therapeutic interventions to alleviate these symptoms are urgently needed. The aim of this study was to investigate the potential neuroprotective effects of voluntary running on cognitive dysfunction in an adeno-associated virus-α-synuclein rat model of PD. Bilateral intranigral administration of adeno-associated virus-α-synuclein was found to induce motor dysfunction and a significant loss of nigral dopaminergic neurons, neither of which were rescued by voluntary running. Overexpression of α-synuclein also resulted in significant impairment on hippocampal neurogenesis-dependent pattern separation, a cognitive task; this was rescued by voluntary running. This was substantiated by an effect of running on neurogenesis levels in the dorsal dentate gyrus, suggesting that the functional effects of running on pattern separation were mediated via increased neurogenesis. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Intercellular transfer of pathogenic α-synuclein by extracellular vesicles is induced by the lipid peroxidation product 4-hydroxynonenal.

    PubMed

    Zhang, Shi; Eitan, Erez; Wu, Tsung-Yu; Mattson, Mark P

    2018-01-01

    Parkinson's disease (PD) is characterized by accumulations of toxic α-synuclein aggregates in vulnerable neuronal populations in the brainstem, midbrain, and cerebral cortex. Recent findings suggest that α-synuclein pathology can be propagated transneuronally, but the underlying molecular mechanisms are unknown. Advances in the genetics of rare early-onset familial PD indicate that increased production and/or reduced autophagic clearance of α-synuclein can cause PD. The cause of the most common late-onset PD is unclear, but may involve metabolic compromise and oxidative stress upstream of α-synuclein accumulation. As evidence, the lipid peroxidation product 4-hydroxynonenal (HNE) is elevated in the brain during normal aging and moreso in brain regions afflicted with α-synuclein pathology. Here, we report that HNE increases aggregation of endogenous α-synuclein in primary neurons and triggers the secretion of extracellular vesicles (EVs) containing cytotoxic oligomeric α-synuclein species. EVs released from HNE-treated neurons are internalized by healthy neurons which as a consequence degenerate. Levels of endogenously generated HNE are elevated in cultured cells overexpressing human α-synuclein, and EVs released from those cells are toxic to neurons. The EV-associated α-synuclein is located both inside the vesicles and on their surface, where it plays a role in EV internalization by neurons. On internalization, EVs harboring pathogenic α-synuclein are transported both anterogradely and retrogradely within axons. Focal injection of EVs containing α-synuclein into the striatum of wild-type mice results in spread of synuclein pathology to anatomically connected brain regions. Our findings suggest a scenario for late-onset PD in which lipid peroxidation promotes intracellular accumulation and then extrusion of EVs containing toxic α-synuclein species; the EVs are then internalized by adjacent neurons, so propagating the neurodegenerative process. Published

  8. FLZ Attenuates α-Synuclein-Induced Neurotoxicity by Activating Heat Shock Protein 70.

    PubMed

    Bao, Xiu-Qi; Wang, Xiao-Liang; Zhang, Dan

    2017-01-01

    Parkinson's disease (PD) is the second most prevalent neurodegenerative disease. The pathology of PD is caused by progressive degeneration of dopaminergic neurons and is characterized by the presence of intracellular inclusions known as Lewy bodies, composed mainly of α-synuclein. Heat shock proteins (HSPs) are crucial in protein quality control in cells. HSP70 in particular prevents the aggregation of protein aggregation, such as α-synuclein, providing a degree of protection against PD. The compound FLZ has been shown to protect several PD models in previous studies and was reported as an HSP inducer to protect against MPP + -induced neurotoxicity, but the mechanism remains unclear. In this study, we investigated the effects of FLZ-mediated HSP70 induction in α-synuclein transgenic mice and cells. FLZ treatment alleviated motor dysfunction and improved dopaminergic neuronal function in α-synuclein transgenic mice. HSP70 protein expression and transcriptional activity were increased by FLZ treatment, eliciting a reduction of α-synuclein aggregation and associated toxicity. The inhibition of HSP70 by quercetin or HSP70 siRNA markedly attenuated the neuroprotective effects of FLZ, confirming that FLZ exerted a neuroprotective effect through HSP70. We revealed that FLZ directly bound to and increased the expression of Hip, a cochaperone of HSP70, which in turn enhanced HSP70 activity. In conclusion, we defined a critical role for HSP70 and its cochaperones activated by FLZ in preventing neurodegeneration and proposed that targeting the HSP70 system may represent a potential therapy for α-synuclein-related diseases, such as PD.

  9. Non-motor parkinsonian pathology in aging A53T α-synuclein mice is associated with progressive synucleinopathy and altered enzymatic function.

    PubMed

    Farrell, Kaitlin F; Krishnamachari, Sesha; Villanueva, Ernesto; Lou, Haiyan; Alerte, Tshianda N M; Peet, Eloise; Drolet, Robert E; Perez, Ruth G

    2014-02-01

    Aging, the main risk factor for Parkinson's disease (PD), is associated with increased α-synuclein levels in substantia nigra pars compacta (SNc). Excess α-synuclein spurs Lewy-like pathology and dysregulates the activity of protein phosphatase 2A (PP2A). PP2A dephosphorylates many neuroproteins, including the catecholamine rate-limiting enzyme, tyrosine hydroxylase (TH). A loss of nigral dopaminergic neurons induces PD movement problems, but before those abnormalities occur, behaviors such as olfactory loss, anxiety, and constipation often manifest. Identifying mouse models with early PD behavioral changes could provide a model in which to test emerging therapeutic compounds. To this end, we evaluated mice expressing A53T mutant human (A53T) α-synuclein for behavior and α-synuclein pathology in olfactory bulb, adrenal gland, and gut. Aging A53T mice exhibited olfactory loss and anxiety that paralleled olfactory and adrenal α-synuclein aggregation. PP2A activity was also diminished in olfactory and adrenal tissues harboring insoluble α-synuclein. Low adrenal PP2A activity co-occurred with TH hyperactivity, making this the first study to link adrenal synucleinopathy to anxiety and catecholamine dysregulation. Aggregated A53T α-synuclein recombinant protein also had impaired stimulatory effects on soluble recombinant PP2A. Collectively, the data identify an excellent model in which to screen compounds for their ability to block the spread of α-synuclein pathology associated with pre-motor stages of PD. © 2013 The Authors. Journal of Neurochemistry published by John Wiley & Sons Ltd on behalf of The International Society for Neurochemistry.

  10. α-Synuclein pathology in the cranial and spinal nerves in Lewy body disease.

    PubMed

    Nakamura, Keiko; Mori, Fumiaki; Tanji, Kunikazu; Miki, Yasuo; Toyoshima, Yasuko; Kakita, Akiyoshi; Takahashi, Hitoshi; Yamada, Masahito; Wakabayashi, Koichi

    2016-06-01

    Accumulation of phosphorylated α-synuclein in neurons and glial cells is a histological hallmark of Lewy body disease (LBD) and multiple system atrophy (MSA). Recently, filamentous aggregations of phosphorylated α-synuclein have been reported in the cytoplasm of Schwann cells, but not in axons, in the peripheral nervous system in MSA, mainly in the cranial and spinal nerve roots. Here we conducted an immunohistochemical investigation of the cranial and spinal nerves and dorsal root ganglia of patients with LBD. Lewy axons were found in the oculomotor, trigeminal and glossopharyngeal-vagus nerves, but not in the hypoglossal nerve. The glossopharyngeal-vagus nerves were most frequently affected, with involvement in all of 20 subjects. In the spinal nerve roots, Lewy axons were found in all of the cases examined. Lewy axons in the anterior nerves were more frequent and numerous in the thoracic and sacral segments than in the cervical and lumbar segments. On the other hand, axonal lesions in the posterior spinal nerve roots appeared to increase along a cervical-to-sacral gradient. Although Schwann cell cytoplasmic inclusions were found in the spinal nerves, they were only minimal. In the dorsal root ganglia, axonal lesions were seldom evident. These findings indicate that α-synuclein pathology in the peripheral nerves is axonal-predominant in LBD, whereas it is restricted to glial cells in MSA. © 2015 Japanese Society of Neuropathology.

  11. Geniposide reduces α-synuclein by blocking microRNA-21/lysosome-associated membrane protein 2A interaction in Parkinson disease models.

    PubMed

    Su, Chunhe; Yang, Xiaopeng; Lou, Jiyu

    2016-08-01

    This study aimed to explore whether the regulatory effect of miR-21 on α-synuclein expression in neurons is a potential mechanism by which geniopside (GP) protects the central nervous system from Parkinson disease (PD). The human neuroblastoma cell line SH-SY5Y was induced to differentiate in vitro and treated with dimethyl sulfoxide (DMSO), N-methyl-4-phenylpyridinium iodide (MPP(+)), and MPP(+) together with GP. To identify the role of miR-21 in the regulation of lysosome-associated membrane protein 2 (LAMP2A) and α-synuclein, SH-SY5Y cells pretreated with MPP(+) were transfected with miR-21 mimic and miR-21 inhibitor. To identify whether GP could reduce the level of α-synuclein through miR-21/LAMP2A, SHSY5Y cells pretreated with GP were treated with miR-21 mimic or miR-21 inhibitor; meanwhile, a luciferase reporter assay was performed to confirm the direct target of miR-21. LAMP2A was overexpressed using a pCMV6-XL5-LAMP2A vector to confirm the role of LAMP2A in the regulation of α-synuclein by miR-21. In these in vitro experiments, the RNA and/or protein expressions of miR-21, LAMP2A, and α-synuclein in SH-SY5Y cells were determined by quantitative real-time polymerase chain reaction and/or western blotting, respectively. An in vivo PD mouse model was established through intraperitoneal injection with N-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP). The mice were treated with saline, MPTP, MPTP+GP, and MPTP+GP+miR-21 agomir. The numbers of TH(+) cells in the substantia nigra in different groups of mice were compared. The RNA and/or protein expressions of miR-21, LAMP2A, and α-synuclein were also determined. The level of miR-21 in the cells or mice models was significantly higher than that in normal cells or normal mice, respectively, and GP significantly downregulated miR-21. GP also raised the protein and mRNA expressions of LAMP2A and reduced the protein level of α-synuclein in PD models. MiR-21 upregulated the expression of α-synuclein by

  12. Role of Different Alpha-Synuclein Strains in Synucleinopathies, Similarities with other Neurodegenerative Diseases

    PubMed Central

    Melki, Ronald

    2015-01-01

    Abstract Misfolded protein aggregates are the hallmark of several neurodegenerative diseases in humans. The main protein constituent of these aggregates and the regions within the brain that are affected differ from one neurodegenerative disorder to another. A plethora of reports suggest that distinct diseases have in common the ability of protein aggregates to spread and amplify within the central nervous system. This review summarizes briefly what is known about the nature of the protein aggregates that are infectious and the reason they are toxic to cells. The chameleon property of polypeptides which aggregation into distinct high-molecular weight assemblies is associated to different diseases, in particular, that of alpha-synuclein which aggregation is the hallmark of distinct synucleinopathies, is discussed. Finally, strategies targeting the formation and propagation of structurally distinct alpha-synuclein assemblies associated to different synucleinopathies are presented and their therapeutic and diagnostic potential is discussed. PMID:25757830

  13. Structural Characteristics of the Alpha-Synuclein Oligomers Stabilized By the Flavonoid Baicalein

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hong, D.-P.; Fink, A.L.; Uversky, V.N.

    The flavonoid baicalein inhibits fibrillation of alpha-synuclein, which is a major component of Lewy bodies in Parkinson's disease. It has been known that baicalein induces the formation of alpha-synuclein oligomers and consequently prevents their fibrillation. In order to evaluate the structural properties of baicalein-stabilized oligomers, we purified oligomer species by HPLC and examined their stability and structure by CD, Fourier transform infrared spectroscopy, size exclusion chromatography HPLC, small-angle X-ray scattering, and atomic force microscopy. Baicalein-stabilized oligomers are beta-sheet-enriched according to CD and Fourier transform infrared spectroscopy analyses. They did not form fibrils even after very prolonged incubation. From small-angle X-raymore » scattering data and atomic force microscopy images, the oligomers were characterized as quite compact globular species. Oligomers were extremely stable, with a GdmCl C(m)=3.3 M. This high stability explains the previously observed inhibition properties of baicalein against alpha-synuclein fibrillation. These baicalein-stabilized oligomers, added to the solution of aggregating alpha-synuclein, were able to noticeably inhibit its fibrillation. After prolonged coincubation, short fibrils were formed, suggesting an effective interaction of oligomers with monomeric alpha-synuclein. Membrane permeability tests suggested that the baicalein-stabilized oligomers had a mild effect on the integrity of the membrane surface. This effect was rather similar to that of the monomeric protein, suggesting that targeted stabilization of certain alpha-synuclein oligomers might offer a potential strategy for the development of novel Parkinson's disease therapies.« less

  14. Drift diffusion model of reward and punishment learning in rare alpha-synuclein gene carriers.

    PubMed

    Moustafa, Ahmed A; Kéri, Szabolcs; Polner, Bertalan; White, Corey

    To understand the cognitive effects of alpha-synuclein polymorphism, we employed a drift diffusion model (DDM) to analyze reward- and punishment-guided probabilistic learning task data of participants with the rare alpha-synuclein gene duplication and age- and education-matched controls. Overall, the DDM analysis showed that, relative to controls, asymptomatic alpha-synuclein gene duplication carriers had significantly increased learning from negative feedback, while they tended to show impaired learning from positive feedback. No significant differences were found in response caution, response bias, or motor/encoding time. We here discuss the implications of these computational findings to the understanding of the neural mechanism of alpha-synuclein gene duplication.

  15. Structures and Free Energy Landscapes of the Wild-Type and A30P Mutant-Type α-Synuclein Proteins with Dynamics

    PubMed Central

    2013-01-01

    The genetic missense A30P mutation of the wild-type α-synuclein protein results in the replacement of the 30th amino acid residue from alanine (Ala) to proline (Pro) and was initially found in the members of a German family who developed Parkinson’s disease. Even though the structures of these proteins have been measured before, detailed understanding about the structures and their relationships with free energy landscapes is lacking, which is of interest to provide insights into the pathogenic mechanism of Parkinson’s disease. We report the secondary and tertiary structures and conformational free energy landscapes of the wild-type and A30P mutant-type α-synuclein proteins in an aqueous solution environment via extensive parallel tempering molecular dynamics simulations along with thermodynamic calculations. In addition, we present the residual secondary structure component transition stabilities at the atomic level with dynamics in terms of free energy change calculations using a new strategy that we reported most recently. Our studies yield new interesting results; for instance, we find that the A30P mutation has local as well as long-range effects on the structural properties of the wild-type α-synuclein protein. The helical content at Ala18-Gly31 is less prominent in comparison to the wild-type α-synuclein protein. The β-sheet structure abundance decreases in the N-terminal region upon A30P mutation of the wild-type α-synuclein, whereas the NAC and C-terminal regions possess larger tendencies for β-sheet structure formation. Long-range intramolecular protein interactions are less abundant upon A30P mutation, especially between the NAC and C-terminal regions, which is linked to the less compact and less stable structures of the A30P mutant-type rather than the wild-type α-synuclein protein. Results including the usage of our new strategy for secondary structure transition stabilities show that the A30P mutant-type α-synuclein tendency toward

  16. Structures and free energy landscapes of the wild-type and A30P mutant-type α-synuclein proteins with dynamics.

    PubMed

    Wise-Scira, Olivia; Aloglu, Ahmet Kemal; Dunn, Aquila; Sakallioglu, Isin Tuna; Coskuner, Orkid

    2013-03-20

    The genetic missense A30P mutation of the wild-type α-synuclein protein results in the replacement of the 30th amino acid residue from alanine (Ala) to proline (Pro) and was initially found in the members of a German family who developed Parkinson's disease. Even though the structures of these proteins have been measured before, detailed understanding about the structures and their relationships with free energy landscapes is lacking, which is of interest to provide insights into the pathogenic mechanism of Parkinson's disease. We report the secondary and tertiary structures and conformational free energy landscapes of the wild-type and A30P mutant-type α-synuclein proteins in an aqueous solution environment via extensive parallel tempering molecular dynamics simulations along with thermodynamic calculations. In addition, we present the residual secondary structure component transition stabilities at the atomic level with dynamics in terms of free energy change calculations using a new strategy that we reported most recently. Our studies yield new interesting results; for instance, we find that the A30P mutation has local as well as long-range effects on the structural properties of the wild-type α-synuclein protein. The helical content at Ala18-Gly31 is less prominent in comparison to the wild-type α-synuclein protein. The β-sheet structure abundance decreases in the N-terminal region upon A30P mutation of the wild-type α-synuclein, whereas the NAC and C-terminal regions possess larger tendencies for β-sheet structure formation. Long-range intramolecular protein interactions are less abundant upon A30P mutation, especially between the NAC and C-terminal regions, which is linked to the less compact and less stable structures of the A30P mutant-type rather than the wild-type α-synuclein protein. Results including the usage of our new strategy for secondary structure transition stabilities show that the A30P mutant-type α-synuclein tendency toward

  17. α-Synuclein oligomers and clinical implications for Parkinson disease

    PubMed Central

    Kalia, Lorraine V.; Kalia, Suneil K.; McLean, Pamela J.; Lozano, Andres M.; Lang, Anthony E.

    2012-01-01

    Protein aggregation within the central nervous system has been recognized as a defining feature of neurodegenerative diseases since the early 20th century. Since that time, there has been a growing list of neurodegenerative disorders, including Parkinson disease, which are characterized by inclusions of specific pathogenic proteins. This has led to the long-held dogma that these characteristic protein inclusions, which are composed of large insoluble fibrillar protein aggregates and visible by light microscopy, are responsible for cell death in these diseases. However, the correlation between protein inclusion formation and cytotoxicity is inconsistent suggesting another form of the pathogenic proteins may be contributing to neurodegeneration. There is emerging evidence implicating soluble oligomers, smaller protein aggregates not detectable by conventional microscopy, as potential culprits in the pathogenesis of neurodegenerative diseases. The protein α-synuclein is well recognized to contribute to the pathogenesis of Parkinson disease and is the major component of Lewy bodies and Lewy neurites. However, α-synuclein also forms oligomeric species with certain conformations being toxic to cells. The mechanisms by which these α-synuclein oligomers cause cell death are being actively investigated as they may provide new strategies for diagnosis and treatment of Parkinson disease and related disorders. Here we review the possible role of α-synuclein oligomers in cell death in Parkinson disease and discuss the potential clinical implications. PMID:23225525

  18. Solid-State NMR Structure of a Pathogenic Fibril of Full-Length Human α-Synuclein

    PubMed Central

    Tuttle, Marcus D.; Comellas, Gemma; Nieuwkoop, Andrew J.; Covell, Dustin J.; Berthold, Deborah A.; Kloepper, Kathryn D.; Courtney, Joseph M.; Kim, Jae K.; Barclay, Alexander M.; Kendall, Amy; Wan, William; Stubbs, Gerald; Schwieters, Charles D.; Lee, Virginia M. Y.; George, Julia M.; Rienstra, Chad M.

    2016-01-01

    Misfolded α-synuclein amyloid fibrils are the principal components of Lewy bodies and neurites, hallmarks of Parkinson’s disease (PD). Here we present a high-resolution structure of an α-synuclein fibril, in a form that induces robust pathology in primary neuronal culture, determined by solid-state NMR spectroscopy and validated by electron microscopy and X-ray fiber diffraction. Over 200 unique long-range distance restraints define a consensus structure with common amyloid features including parallel in-register β-sheets and hydrophobic core residues, but also substantial complexity, arising from diverse structural features: an intermolecular salt bridge, a glutamine ladder, close backbone interactions involving small residues, and several steric zippers stabilizing a novel, orthogonal Greek-key topology. These characteristics contribute to the robust propagation of this fibril form, as evidenced by structural similarity of early-onset PD mutants. The structure provides a framework for understanding the interactions of α-synuclein with other proteins and small molecules to diagnose and treat PD. PMID:27018801

  19. Genetic reduction of mitochondrial complex I function does not lead to loss of dopamine neurons in vivo.

    PubMed

    Kim, Hyung-Wook; Choi, Won-Seok; Sorscher, Noah; Park, Hyung Joon; Tronche, François; Palmiter, Richard D; Xia, Zhengui

    2015-09-01

    Inhibition of mitochondrial complex I activity is hypothesized to be one of the major mechanisms responsible for dopaminergic neuron death in Parkinson's disease. However, loss of complex I activity by systemic deletion of the Ndufs4 gene, one of the subunits comprising complex I, does not cause dopaminergic neuron death in culture. Here, we generated mice with conditional Ndufs4 knockout in dopaminergic neurons (Ndufs4 conditional knockout mice [cKO]) to examine the effect of complex I inhibition on dopaminergic neuron function and survival during aging and on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment in vivo. Ndufs4 cKO mice did not show enhanced dopaminergic neuron loss in the substantia nigra pars compacta or dopamine-dependent motor deficits over the 24-month life span. These mice were just as susceptible to MPTP as control mice. However, compared with control mice, Ndufs4 cKO mice exhibited an age-dependent reduction of dopamine in the striatum and increased α-synuclein phosphorylation in dopaminergic neurons of the substantia nigra pars compacta. We also used an inducible Ndufs4 knockout mouse strain (Ndufs4 inducible knockout) in which Ndufs4 is conditionally deleted in all cells in adult to examine the effect of adult onset, complex I inhibition on MPTP sensitivity of dopaminergic neurons. The Ndufs4 inducible knockout mice exhibited similar sensitivity to MPTP as control littermates. These data suggest that mitochondrial complex I inhibition in dopaminergic neurons does contribute to dopamine loss and the development of α-synuclein pathology. However, it is not sufficient to cause cell-autonomous dopaminergic neuron death during the normal life span of mice. Furthermore, mitochondrial complex I inhibition does not underlie MPTP toxicity in vivo in either cell autonomous or nonautonomous manner. These results provide strong evidence that inhibition of mitochondrial complex I activity is not sufficient to cause dopaminergic neuron

  20. The NACP/synuclein gene: chromosomal assignment and screening for alterations in Alzheimer disease.

    PubMed

    Campion, D; Martin, C; Heilig, R; Charbonnier, F; Moreau, V; Flaman, J M; Petit, J L; Hannequin, D; Brice, A; Frebourg, T

    1995-03-20

    The major component of the vascular and plaque amyloid deposits in Alzheimer disease is the amyloid beta peptide (A beta). A second intrinsic component of amyloid, the NAC (non-A beta component of amyloid) peptide, has recently been identified, and its precursor protein was named NACP. A computer homology search allowed us to establish that the human NACP gene was homologous to the rat synuclein gene. We mapped the NACP/synuclein gene to chromosome 4 and cloned three alternatively spliced transcripts in lymphocytes derived from a normal subject. We analyzed by RT-PCR and direct sequencing the entire coding region of the NACP/synuclein gene in a group of patients with familial early onset Alzheimer disease. No mutation was found in 26 unrelated patients. Further studies are required to investigate the implication of the NACP/synuclein gene in Alzheimer disease.

  1. Validation of a commercially available enzyme-linked immunoabsorbent assay for the quantification of human α-Synuclein in cerebrospinal fluid.

    PubMed

    Kruse, Niels; Mollenhauer, Brit

    2015-11-01

    The quantification of α-Synuclein in cerebrospinal fluid (CSF) as a biomarker has gained tremendous interest in the last years. Several commercially available immunoassays are emerging. We here describe the full validation of one commercially available ELISA assay for the quantification of α-Synuclein in human CSF (Covance alpha-Synuclein ELISA kit). The study was conducted within the BIOMARKAPD project in the European initiative Joint Program for Neurodegenerative Diseases (JPND). We investigated the effect of several pre-analytical and analytical confounders: i.e. (1) need for centrifugation of freshly drawn CSF, (2) sample stability, (3) delay of freezing, (4) volume of storage aliquots, (5) freeze/thaw cycles, (6) thawing conditions, (7) dilution linearity, (8) parallelism, (9) spike recovery, and (10) precision. None of these confounders influenced the levels of α-Synuclein in CSF significantly. We found a very high intra-assay precision. The inter-assay precision was lower than expected due to different performances of kit lots used. Overall the validated immunoassay is useful for the quantification of α-Synuclein in human CSF. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Reduced TH expression and α-synuclein accumulation contribute towards nigrostriatal dysfunction in experimental hepatic encephalopathy.

    PubMed

    Suárez, Isabel; Bodega, Guillermo; Rubio, Miguel; Fernández, Benjamín

    2017-01-01

    The present work examines α-synuclein expression in the nigrostriatal system of a rat chronic hepatic encephalopathy model induced by portacaval anastomosis (PCA). There is evidence that dopaminergic dysfunction in disease conditions is strongly associated with such expression. Possible relationships among dopaminergic neurons, astroglial cells and α-synuclein expression were sought. Brain tissue samples from rats at 1 and 6 months post-PCA, and controls, were analysed immunohistochemically using antibodies against tyrosine hydroxylase (TH), α-synuclein, glial fibrillary acidic protein (GFAP) and ubiquitin (Ub). In the control rats, TH immunoreactivity was detected in the neuronal cell bodies and processes in the substantia nigra pars compacta (SNc). A dense TH-positive network of neurons was also seen in the striatum. In the PCA-exposed rats, however, a reduction in TH-positive neurons was seen at both 1 and 6 months in the SNc, as well as a reduction in TH-positive fibres in the striatum. This was coincident with the appearance of α-synuclein-immunoreactive neurons in the SNc; some of the TH-positive neurons also showed α-synuclein immunoreactivity. In addition, α-synuclein accumulation was seen in the SNc and striatum at both 1 and 6 months post-PCA, whereas α-synuclein was only mildly expressed in the nigrostriatal pathway of the controls. Astrogliosis was also seen following PCA, as revealed by increased GFAP expression from 1 month to 6 months post-PCA in both the SN and striatum. The astroglial activation level in the SN paralleled the reduced neuronal expression of TH throughout PCA exposure. α-synuclein accumulation following PCA may induce dopaminergic dysfunction via the downregulation of TH, as well as astroglial activation.

  3. Increased Frequency of α-Synuclein in the Substantia Nigra in HIV Infection

    PubMed Central

    Khanlou, Negar; Moore, David J.; Chana, Gursharan; Cherner, Mariana; Lazzaretto, Deborah; Dawes, Sharron; Grant, Igor; Masliah, Eliezer; Everall, Ian P.

    2014-01-01

    The frequency of neurodegenerative markers among long surviving HIV infected individuals is unknown, therefore, the present study investigated the frequency of α-synuclein, β-amyloid and HIV-associated brain pathology in the brains of older HIV infected individuals. We examined the substantia nigra of 73 clinically well-characterized HIV infected individuals aged 50 to 76 years from the National NeuroAIDS Tissue Consortium. We also examined the frontal and temporal cortical regions of a subset of 36 individuals. The brain regions were examined for the presence of α-synuclein, β-amyloid and HIV-associated brain pathology. Neuritic α-synuclein expression was found in 16% (12/73) of the substantia nigra of the HIV+ cases and none of the older control cases (0/18). β-amyloid deposits were prevalent and found in nearly all of the HIV+ cases (35/36). Despite these increases of degenerative pathology, HIV-associated brain pathology was present in only 10% of cases. Among older HIV+ adults HIV-associated brain pathology does not appear elevated; however, the frequency of both α-synuclein and β-amyloid is higher than that found in older healthy persons. The increased prevalence of α-synuclein and β-amyloid in the brains of older HIV-infected individuals may predict an increased risk of developing neurodegenerative disease. PMID:19115126

  4. The NACP/synuclein gene: Chromosomal assignment and screening for alterations in Alzheimer disease

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Campion, D.; Martin, C.; Charbonnier, F.

    1995-03-20

    The major component of the vascular and plaque amyloid deposits in Alzheimer disease is the amyloid {beta} peptide (A{beta}). A second intrinsic component of amyloid, the NAC (non-A{beta} component of amyloid) peptide, has recently been identified, and its precursor protein was named NACP. A computer homology search allowed us to establish that the human NACP gene was homologous to the rat synuclein gene. We mapped the NACP/synuclein gene to chromosome 4 and cloned three alternatively spliced transcripts in lymphocytes derived from a normal subject. We analyzed by RT-PCR and direct sequencing the entire coding region of the NACP/synuclein gene inmore » a group of patients with familial early onset Alzheimer disease. No mutation was found in 26 unrelated patients. Further studies are required to investigate the implication of the NACP/synuclein gene in Alzheimer disease. 21 refs., 3 tabs.« less

  5. Dopamine, reward learning, and active inference.

    PubMed

    FitzGerald, Thomas H B; Dolan, Raymond J; Friston, Karl

    2015-01-01

    Temporal difference learning models propose phasic dopamine signaling encodes reward prediction errors that drive learning. This is supported by studies where optogenetic stimulation of dopamine neurons can stand in lieu of actual reward. Nevertheless, a large body of data also shows that dopamine is not necessary for learning, and that dopamine depletion primarily affects task performance. We offer a resolution to this paradox based on an hypothesis that dopamine encodes the precision of beliefs about alternative actions, and thus controls the outcome-sensitivity of behavior. We extend an active inference scheme for solving Markov decision processes to include learning, and show that simulated dopamine dynamics strongly resemble those actually observed during instrumental conditioning. Furthermore, simulated dopamine depletion impairs performance but spares learning, while simulated excitation of dopamine neurons drives reward learning, through aberrant inference about outcome states. Our formal approach provides a novel and parsimonious reconciliation of apparently divergent experimental findings.

  6. A Test of the Transdiagnostic Dopamine Hypothesis of Psychosis Using Positron Emission Tomographic Imaging in Bipolar Affective Disorder and Schizophrenia.

    PubMed

    Jauhar, Sameer; Nour, Matthew M; Veronese, Mattia; Rogdaki, Maria; Bonoldi, Ilaria; Azis, Matilda; Turkheimer, Federico; McGuire, Philip; Young, Allan H; Howes, Oliver D

    2017-12-01

    The dopamine hypothesis suggests that dopamine abnormalities underlie psychosis, irrespective of diagnosis, implicating dopamine dysregulation in bipolar affective disorder and schizophrenia, in line with the research domain criteria approach. However, this hypothesis has not been directly examined in individuals diagnosed with bipolar disorder with psychosis. To test whether dopamine synthesis capacity is elevated in bipolar disorder with psychosis and how this compares with schizophrenia and matched controls and to examine whether dopamine synthesis capacity is associated with psychotic symptom severity, irrespective of diagnostic class. This cross-sectional case-control positron emission tomographic study was performed in the setting of first-episode psychosis services in an inner-city area (London, England). Sixty individuals participated in the study (22 with bipolar psychosis [18 antipsychotic naive or free], 16 with schizophrenia [14 antipsychotic naive or free], and 22 matched controls) and underwent fluorodihydroxyphenyl-l-alanine ([18F]-DOPA) positron emission tomography to examine dopamine synthesis capacity. Standardized clinical measures, including the Positive and Negative Syndrome Scale, Young Mania Rating Scale, and Global Assessment of Functioning, were administered. The study dates were March 2013 to November 2016. Dopamine synthesis capacity (Kicer) and clinical measures (Positive and Negative Syndrome Scale, Young Mania Rating Scale, and Global Assessment of Functioning). The mean (SD) ages of participants were 23.6 (3.6) years in 22 individuals with bipolar psychosis (13 male), 26.3 (4.4) years in 16 individuals with schizophrenia (14 male), and 24.5 (4.5) years in controls (14 male). There was a significant group difference in striatal dopamine synthesis capacity (Kicer) (F2,57 = 6.80, P = .002). Kicer was significantly elevated in both the bipolar group (mean [SD], 13.18 [1.08] × 10-3 min-1; P = .002) and the schizophrenia

  7. Expression of alpha-synuclein during eye development of mice (Mus musculus), chick (Gallus gallus domisticus) and fish (Ctenopharyngodon idella) in a comparison study.

    PubMed

    Seleem, Amin A

    2015-08-01

    Synucleins are small proteins associated with neurodegenerative diseases, alpha-synuclein is a Parkinson's disease-linked protein of ubiquitous expression in the central nervous system. This study aimed at the localization of alpha-synuclein during eye development of mice (Mus musculus), chick (Gallus gallus domisticus) and fish (Ctenopharyngodon idella) by immunohistochemical staining in a comparison study. The results showed that alpha-synuclein expression increased gradually with the development of ciliary body, iris, retina and cornea of mice at E17, P1, P3, P7 and chick at E5, E10, E15 with unequal appearance of alpha-synuclein expression. Also, it was not detected in iridocorneal angle during eye development of mice and chick. Alpha-synuclein expression during fish eye development at P10, P15, P20 was not detected either in the ciliray body or Iris regions and it was pronounced with sharp signals in the highly specialized tissue of the iridocorneal angle at P20. Also, the expression was gradually increased from P15 to P20 in fish retina and cornea. The pattern of expression and distribution of alpha-synuclein during the development of ciliary body and iris of mice, chick and fish has not been previously characterized, The data concluded that alpha-synuclein has important cellular function during eye development of studied animals. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Acute fasting increases somatodendritic dopamine release in the ventral tegmental area

    PubMed Central

    2015-01-01

    Fasting and food restriction alter the activity of the mesolimbic dopamine system to affect multiple reward-related behaviors. Food restriction decreases baseline dopamine levels in efferent target sites and enhances dopamine release in response to rewards such as food and drugs. In addition to releasing dopamine from axon terminals, dopamine neurons in the ventral tegmental area (VTA) also release dopamine from their soma and dendrites, and this somatodendritic dopamine release acts as an autoinhibitory signal to inhibit neighboring VTA dopamine neurons. It is unknown whether acute fasting also affects dopamine release, including the local inhibitory somatodendritic dopamine release in the VTA. In these studies, I have tested whether fasting affects the inhibitory somatodendritic dopamine release within the VTA by examining whether an acute 24-h fast affects the inhibitory postsynaptic current mediated by evoked somatodendritic dopamine release (D2R IPSC). Fasting increased the contribution of the first action potential to the overall D2R IPSC and increased the ratio of repeated D2R IPSCs evoked at short intervals. Fasting also reduced the effect of forskolin on the D2R IPSC and led to a significantly bigger decrease in the D2R IPSC in low extracellular calcium. Finally, fasting resulted in an increase in the D2R IPSCs when a more physiologically relevant train of D2R IPSCs was used. Taken together, these results indicate that fasting caused a change in the properties of somatodendritic dopamine release, possibly by increasing dopamine release, and that this increased release can be sustained under conditions where dopamine neurons are highly active. PMID:26084913

  9. A combination of dopamine genes predicts success by professional Wall Street traders.

    PubMed

    Sapra, Steve; Beavin, Laura E; Zak, Paul J

    2012-01-01

    What determines success on Wall Street? This study examined if genes affecting dopamine levels of professional traders were associated with their career tenure. Sixty professional Wall Street traders were genotyped and compared to a control group who did not trade stocks. We found that distinct alleles of the dopamine receptor 4 promoter (DRD4P) and catecholamine-O-methyltransferase (COMT) that affect synaptic dopamine were predominant in traders. These alleles are associated with moderate, rather than very high or very low, levels of synaptic dopamine. The activity of these alleles correlated positively with years spent trading stocks on Wall Street. Differences in personality and trading behavior were also correlated with allelic variants. This evidence suggests there may be a genetic basis for the traits that make one a successful trader.

  10. A Combination of Dopamine Genes Predicts Success by Professional Wall Street Traders

    PubMed Central

    Sapra, Steve; Beavin, Laura E.; Zak, Paul J.

    2012-01-01

    What determines success on Wall Street? This study examined if genes affecting dopamine levels of professional traders were associated with their career tenure. Sixty professional Wall Street traders were genotyped and compared to a control group who did not trade stocks. We found that distinct alleles of the dopamine receptor 4 promoter (DRD4P) and catecholamine-O-methyltransferase (COMT) that affect synaptic dopamine were predominant in traders. These alleles are associated with moderate, rather than very high or very low, levels of synaptic dopamine. The activity of these alleles correlated positively with years spent trading stocks on Wall Street. Differences in personality and trading behavior were also correlated with allelic variants. This evidence suggests there may be a genetic basis for the traits that make one a successful trader. PMID:22292056

  11. Dopamine, reward learning, and active inference

    PubMed Central

    FitzGerald, Thomas H. B.; Dolan, Raymond J.; Friston, Karl

    2015-01-01

    Temporal difference learning models propose phasic dopamine signaling encodes reward prediction errors that drive learning. This is supported by studies where optogenetic stimulation of dopamine neurons can stand in lieu of actual reward. Nevertheless, a large body of data also shows that dopamine is not necessary for learning, and that dopamine depletion primarily affects task performance. We offer a resolution to this paradox based on an hypothesis that dopamine encodes the precision of beliefs about alternative actions, and thus controls the outcome-sensitivity of behavior. We extend an active inference scheme for solving Markov decision processes to include learning, and show that simulated dopamine dynamics strongly resemble those actually observed during instrumental conditioning. Furthermore, simulated dopamine depletion impairs performance but spares learning, while simulated excitation of dopamine neurons drives reward learning, through aberrant inference about outcome states. Our formal approach provides a novel and parsimonious reconciliation of apparently divergent experimental findings. PMID:26581305

  12. Mitochondria and α-Synuclein: Friends or Foes in the Pathogenesis of Parkinson's Disease?

    PubMed

    Faustini, Gaia; Bono, Federica; Valerio, Alessandra; Pizzi, Marina; Spano, PierFranco; Bellucci, Arianna

    2017-12-08

    Parkinson's disease (PD) is a movement disorder characterized by dopaminergic nigrostriatal neuron degeneration and the formation of Lewy bodies (LB), pathological inclusions containing fibrils that are mainly composed of α-synuclein. Dopaminergic neurons, for their intrinsic characteristics, have a high energy demand that relies on the efficiency of the mitochondria respiratory chain. Dysregulations of mitochondria, deriving from alterations of complex I protein or oxidative DNA damage, change the trafficking, size and morphology of these organelles. Of note, these mitochondrial bioenergetics defects have been related to PD. A series of experimental evidence supports that α-synuclein physiological action is relevant for mitochondrial homeostasis, while its pathological aggregation can negatively impinge on mitochondrial function. It thus appears that imbalances in the equilibrium between the reciprocal modulatory action of mitochondria and α-synuclein can contribute to PD onset by inducing neuronal impairment. This review will try to highlight the role of physiological and pathological α-synuclein in the modulation of mitochondrial functions.

  13. α - synuclein under the magnifying glass. Insights from atomistic and coarse-grain simulations

    NASA Astrophysics Data System (ADS)

    Ilie, Ioana M.; Nayar, Divya; den Otter, Wouter K.; van der Vegt, Nico F. A.; Briels, Wim J.; University of Twente Collaboration; University of Darmstadt Collaboration

    Neurodegenerative diseases are linked to the accumulation of misfolded intrinsically disordered proteins in the brain. Here, we use both all-atom and coarse-grain simulations to explore the intricate dynamics and the aggregation of α-synuclein, the protein implicated in Parkinson's disease. We explore the free energy landscapes of α-synuclein by using Molecular Dynamics simulations and extract information on the structure of the protein as well as on its binding affinities. Next, to study the aggregation, we proceed with representing α-synuclein as a chain of deformable particles that can adapt their geometry, binding affinities and can rearrange into different disordered and ordered structures. We use Brownian Dynamics to simulate the translational and rotational motions of the particles, as well as their interaction properties. The simulations show valuable insight into the internal dynamics of α-synuclein and the formation of ordered and disordered aggregates. In addition, the study is extended to investigate the attachment and folding of a protein to a fiber.

  14. Biophysics of α-Synuclein Membrane Interactions

    PubMed Central

    Pfefferkorn, Candace M.; Jiang, Zhiping; Lee, Jennifer C.

    2011-01-01

    Membrane proteins participate in nearly all cellular processes; however, because of experimental limitations, their characterization lags far behind that of soluble proteins. Peripheral membrane proteins are particularly challenging to study because of their inherent propensity to adopt multiple and/or transient conformations in solution and upon membrane association. In this review, we summarize useful biophysical techniques for the study of peripheral membrane proteins and their application in the characterization of the membrane interactions of the natively unfolded and Parkinson’s disease (PD) related protein, α-synuclein (α-syn). We give particular focus to studies that have led to the current understanding of membrane-bound α-syn structure and the elucidation of specific membrane properties that affect α-syn-membrane binding. Finally, we discuss biophysical evidence supporting a key role for membranes and α-syn in PD pathogenesis. PMID:21819966

  15. Blockade of the dopamine depressor response by molindone, a newly introduced neuroleptic.

    PubMed

    Nandal, N V; Mane, V R; Balsara, J J; Chandorkar, A G

    1980-01-01

    Pretreatment with the neuroleptics, haloperidol and molindone, significantly antagonized the dopamine-induced depressor response in the anaesthetized dogs. The depressor response to dopamine was however, not significantly affected by propranolol, atropine or antazoline pretreatment. The results suggest that molindone like haloperidol, is capable of blocking the vascular dopamine receptors responsible for mediating dopamine-induced vasodilatation in the coeliac, mesenteric and renal vascular bed and fall in blood pressure.

  16. Impact of hydrostatic pressure on an intrinsically disordered protein: a high-pressure NMR study of α-synuclein.

    PubMed

    Roche, Julien; Ying, Jinfa; Maltsev, Alexander S; Bax, Ad

    2013-09-23

    The impact of pressure on the backbone (15) N, (1) H and (13) C chemical shifts in N-terminally acetylated α-synuclein has been evaluated over a pressure range 1-2500 bar. Even while the chemical shifts fall very close to random coil values, as expected for an intrinsically disordered protein, substantial deviations in the pressure dependence of the chemical shifts are seen relative to those in short model peptides. In particular, the nonlinear pressure response of the (1) H(N) chemical shifts, which commonly is associated with the presence of low-lying "excited states", is much larger in α-synuclein than in model peptides. The linear pressure response of (1) H(N) chemical shift, commonly linked to H-bond length change, correlates well with those in short model peptides, and is found to be anticorrelated with its temperature dependence. The pressure dependence of (13) C chemical shifts shows remarkably large variations, even when accounting for residue type, and do not point to a clear shift in population between different regions of the Ramachandran map. However, a nearly universal decrease in (3) JHN-Hα by 0.22 ± 0.05 Hz suggests a slight increase in population of the polyproline II region at 2500 bar. The first six residues of N-terminally acetylated synuclein show a transient of approximately 15% population of α-helix, which slightly diminishes at 2500 bar. The backbone dynamics of the protein is not visibly affected beyond the effect of slight increase in water viscosity at 2500 bar. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Prefrontocortical dopamine loss in rats delays long-term extinction of contextual conditioned fear, and reduces social interaction without affecting short-term social interaction memory.

    PubMed

    Fernandez Espejo, Emilio

    2003-03-01

    Prefrontal dopamine loss delays extinction of cued fear conditioning responses, but its role in contextual fear conditioning has not been explored. Medial prefrontal lesions also enhance social interaction in rats, but the role of prefrontal dopamine loss on social interaction memory is not known. Besides, a role for subcortical accumbal dopamine on mnesic changes after prefrontal dopamine manipulation has been proposed but not explored. The objective was to study the involvement of dopaminergic neurotransmission in the medial prefrontal cortex (mPFC) and nucleus accumbens in two mnesic tasks: contextual fear conditioning and social interaction memory. For contextual fear conditioning, short- and long-term freezing responses after an electric shock were studied, as well as extinction retention. Regarding social interaction memory, the recognition of a juvenile, a very sensitive short-term memory test, was used. Dopamine loss was carried out by injection of 6-hydroxydopamine, and postmortem catecholamine levels were analyzed by high-performance liquid chromatography. Prefrontocortical dopamine loss (>76%) led to a reactive enhancement of accumbal dopamine content (p<0.01), supporting the hypothesis that a hyperdopaminergic tone emerges in the nucleus accumbens after prefrontocortical dopamine loss. In lesioned rats, long-term extinction of contextual fear conditioning was significantly delayed and extinction retention was impaired without changes in acquisition and short-term contextual fear conditioning and, on the other hand, acquisition and short-term social interaction memory were not affected, although time spent on social interaction was significantly reduced. Added dopamine loss in the nucleus accumbens (>76%) did not alter these behavioral changes. In summary, the results of the present study indicate that the dopaminergic network in the mPFC (but not in the nucleus accumbens) coordinates the normal long-term extinction of contextual fear conditioning

  18. Evidence of native α-synuclein conformers in the human brain.

    PubMed

    Gould, Neal; Mor, Danielle E; Lightfoot, Richard; Malkus, Kristen; Giasson, Benoit; Ischiropoulos, Harry

    2014-03-14

    α-Synuclein aggregation is central to the pathogenesis of several brain disorders. However, the native conformations and functions of this protein in the human brain are not precisely known. The native state of α-synuclein was probed by gel filtration coupled with native gradient gel separation, an array of antibodies with non-overlapping epitopes, and mass spectrometry. The existence of metastable conformers and stable monomer was revealed in the human brain.

  19. Acrolein acts as a neurotoxin in the nigrostriatal dopaminergic system of rat: involvement of α-synuclein aggregation and programmed cell death

    PubMed Central

    Wang, Yi-Ting; Lin, Hui-Ching; Zhao, Wei-Zhong; Huang, Hui-Ju; Lo, Yu-Li; Wang, Hsiang-Tsui; Maan-Yuh Lin, Anya

    2017-01-01

    Clinical studies report significant increases in acrolein (an α,β-unsaturated aldehyde) in the substantia nigra (SN) of patients with Parkinson’s disease (PD). In the present study, acrolein-induced neurotoxicity in the nigrostriatal dopaminergic system was investigated by local infusion of acrolein (15, 50, 150 nmoles/0.5 μl) in the SN of Sprague-Dawley rats. Acrolein-induced neurodegeneration of nigrostriatal dopaminergic system was delineated by reductions in tyrosine hydroxylase (TH) levels, dopamine transporter levels and TH-positive neurons in the infused SN as well as in striatal dopamine content. At the same time, apomorphine-induced turning behavior was evident in rats subjected to a unilateral infusion of acrolein in SN. Acrolein was pro-oxidative by increasing 4-hydroxy-2-nonenal and heme oxygenase-1 levels. Furthermore, acrolein conjugated with proteins at lysine residue and induced α-synuclein aggregation in the infused SN. Acrolein was pro-inflammatory by activating astrocytes and microglia. In addition, acrolein activated caspase 1 in the infused SN, suggesting acrolein-induced inflammasome formation. The neurotoxic mechanisms underlying acrolein-induced neurotoxicity involved programmed cell death, including apoptosis and necroptosis. Compared with well-known Parkinsonian neurotoxins, including 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and rotenone which do not exist in the SN of PD patients, our in vivo study shows that acrolein acts as a Parkinsonian neurotoxin in the nigrostriatal dopaminergic system of rat brain. PMID:28401906

  20. Oral Exposure to Paraquat Triggers Earlier Expression of Phosphorylated α-Synuclein in the Enteric Nervous System of A53T Mutant Human α-Synuclein Transgenic Mice

    PubMed Central

    Naudet, Nicolas; Antier, Emilie; Gaillard, Damien; Morignat, Eric; Lakhdar, Latifa; Baron, Thierry; Bencsik, Anna

    2017-01-01

    Abstract The misfolded α-synuclein protein, phosphorylated at serine 129 (pSer129 α-syn), is the hallmark of Parkinson disease (PD). Detected also in the enteric nervous system (ENS), it supports the recent theory that PD could start in the gut, rather than the brain. In a previous study, using a transgenic mouse model of human synucleinopathies expressing the A53T mutant α-synuclein (TgM83), in which a neurodegenerative process associated with α-synuclein occurs spontaneously in the brain, we have shown earlier onset of pSer129 α-syn in the ENS. Here, we used this model to study the impact of paraquat (PQ) a neurotoxic herbicide incriminated in PD in agricultural workers) on the enteric pSer129 α-syn expression in young mice. Orally delivered in the drinking water at 10 mg/kg/day for 6–8 weeks, the impact of PQ was measured in a time-dependent manner on weight, locomotor abilities, pSer129 α-syn, and glial fibrillary acidic protein (GFAP) expression levels in the ENS. Remarkably, pSer129 α-syn was detected in ENS earlier under PQ oral exposure and enteric GFAP expression was also increased. These findings bring additional support to the theory that neurotoxic agents such as PQ initiate idiopathic PD after oral delivery. PMID:29040593

  1. Oral Exposure to Paraquat Triggers Earlier Expression of Phosphorylated α-Synuclein in the Enteric Nervous System of A53T Mutant Human α-Synuclein Transgenic Mice.

    PubMed

    Naudet, Nicolas; Antier, Emilie; Gaillard, Damien; Morignat, Eric; Lakhdar, Latifa; Baron, Thierry; Bencsik, Anna

    2017-12-01

    The misfolded α-synuclein protein, phosphorylated at serine 129 (pSer129 α-syn), is the hallmark of Parkinson disease (PD). Detected also in the enteric nervous system (ENS), it supports the recent theory that PD could start in the gut, rather than the brain. In a previous study, using a transgenic mouse model of human synucleinopathies expressing the A53T mutant α-synuclein (TgM83), in which a neurodegenerative process associated with α-synuclein occurs spontaneously in the brain, we have shown earlier onset of pSer129 α-syn in the ENS. Here, we used this model to study the impact of paraquat (PQ) a neurotoxic herbicide incriminated in PD in agricultural workers) on the enteric pSer129 α-syn expression in young mice. Orally delivered in the drinking water at 10 mg/kg/day for 6-8 weeks, the impact of PQ was measured in a time-dependent manner on weight, locomotor abilities, pSer129 α-syn, and glial fibrillary acidic protein (GFAP) expression levels in the ENS. Remarkably, pSer129 α-syn was detected in ENS earlier under PQ oral exposure and enteric GFAP expression was also increased. These findings bring additional support to the theory that neurotoxic agents such as PQ initiate idiopathic PD after oral delivery. © 2017 American Association of Neuropathologists, Inc.

  2. Monomeric and fibrillar α-synuclein exert opposite effects on the catalytic cycle that promotes the proliferation of Aβ42 aggregates

    PubMed Central

    Chia, Sean; Habchi, Johnny; Lattanzi, Veronica; Dobson, Christopher M.; Knowles, Tuomas P. J.; Vendruscolo, Michele

    2017-01-01

    The coaggregation of the amyloid-β peptide (Aβ) and α-synuclein is commonly observed in a range of neurodegenerative disorders, including Alzheimer’s and Parkinson’s diseases. The complex interplay between Aβ and α-synuclein has led to seemingly contradictory results on whether α-synuclein promotes or inhibits Aβ aggregation. Here, we show how these conflicts can be rationalized and resolved by demonstrating that different structural forms of α-synuclein exert different effects on Aβ aggregation. Our results demonstrate that whereas monomeric α-synuclein blocks the autocatalytic proliferation of Aβ42 (the 42-residue form of Aβ) fibrils, fibrillar α-synuclein catalyses the heterogeneous nucleation of Aβ42 aggregates. It is thus the specific balance between the concentrations of monomeric and fibrillar α-synuclein that determines the outcome of the Aβ42 aggregation reaction. PMID:28698377

  3. Methamphetamine Regulation of Firing Activity of Dopamine Neurons

    PubMed Central

    Lin, Min; Sambo, Danielle

    2016-01-01

    Methamphetamine (METH) is a substrate for the dopamine transporter that increases extracellular dopamine levels by competing with dopamine uptake and increasing reverse transport of dopamine via the transporter. METH has also been shown to alter the excitability of dopamine neurons. The mechanism of METH regulation of the intrinsic firing behaviors of dopamine neurons is less understood. Here we identified an unexpected and unique property of METH on the regulation of firing activity of mouse dopamine neurons. METH produced a transient augmentation of spontaneous spike activity of midbrain dopamine neurons that was followed by a progressive reduction of spontaneous spike activity. Inspection of action potential morphology revealed that METH increased the half-width and produced larger coefficients of variation of the interspike interval, suggesting that METH exposure affected the activity of voltage-dependent potassium channels in these neurons. Since METH has been shown to affect Ca2+ homeostasis, the unexpected findings that METH broadened the action potential and decreased the amplitude of afterhyperpolarization led us to ask whether METH alters the activity of Ca2+-activated potassium (BK) channels. First, we identified BK channels in dopamine neurons by their voltage dependence and their response to a BK channel blocker or opener. While METH suppressed the amplitude of BK channel-mediated unitary currents, the BK channel opener NS1619 attenuated the effects of METH on action potential broadening, afterhyperpolarization repression, and spontaneous spike activity reduction. Live-cell total internal reflection fluorescence microscopy, electrophysiology, and biochemical analysis suggest METH exposure decreased the activity of BK channels by decreasing BK-α subunit levels at the plasma membrane. SIGNIFICANCE STATEMENT Methamphetamine (METH) competes with dopamine uptake, increases dopamine efflux via the dopamine transporter, and affects the excitability of

  4. A microRNA embedded AAV alpha-synuclein gene silencing vector for dopaminergic neurons

    PubMed Central

    Han, Ye; Khodr, Christina E.; Sapru, Mohan K.; Pedapati, Jyothi; Bohn, Martha C.

    2011-01-01

    Alpha-synuclein (SNCA), an abundantly expressed presynaptic protein, is implicated in Parkinson disease (PD). Since over-expression of human SNCA (hSNCA) leads to death of dopaminergic (DA) neurons in human, rodent and fly brain, hSNCA gene silencing may reduce levels of toxic forms of SNCA and ameliorate degeneration of DA neurons in PD. To begin to develop a gene therapy for PD based on hSNCA gene silencing, two AAV gene silencing vectors were designed, and tested for efficiency and specificity of silencing, as well as toxicity in vitro. The same hSNCA silencing sequence (shRNA) was used in both vectors, but in one vector, the shRNA was embedded in a microRNA backbone and driven by a pol II promoter, and in the other the shRNA was not embedded in a microRNA and was driven by a pol III promoter. Both vectors silenced hSNCA to the same extent in 293T cells transfected with hSNCA. In DA PC12 cells, neither vector decreased expression of rat SNCA, tyrosine hydroxylase (TH), dopamine transporter (DAT) or the vesicular monoamine transporter (VMAT). However, the mir30 embedded vector was significantly less toxic to both PC12 and SH-SY5Y cells. Our in vitro data suggest that this miRNA-embedded silencing vector may be ideal for chronic in vivo SNCA gene silencing in DA neurons. PMID:21338582

  5. Rotenone and elevated extracellular potassium concentration induce cell-specific fibrillation of α-synuclein in axons of cholinergic enteric neurons in the guinea-pig ileum.

    PubMed

    Sharrad, D F; Chen, B N; Gai, W P; Vaikath, N; El-Agnaf, O M; Brookes, S J H

    2017-04-01

    Parkinson's disease is a progressive neurodegenerative disorder that results in the widespread loss of select classes of neurons throughout the nervous system. The pathological hallmarks of Parkinson's disease are Lewy bodies and neurites, of which α-synuclein fibrils are the major component. α-Synuclein aggregation has been reported in the gut of Parkinson's disease patients, even up to a decade before motor symptoms, and similar observations have been made in animal models of disease. However, unlike the central nervous system, the nature of α-synuclein species that form these aggregates and the classes of neurons affected in the gut are unclear. We have previously reported selective expression of α-synuclein in cholinergic neurons in the gut (J Comp Neurol. 2013; 521:657), suggesting they may be particularly vulnerable to degeneration in Parkinson's disease. In this study, we used immunohistochemistry to detect α-synuclein oligomers and fibrils via conformation-specific antibodies after rotenone treatment or prolonged exposure to high [K + ] in ex vivo segments of guinea-pig ileum maintained in organotypic culture. Rotenone and prolonged raising of [K + ] caused accumulation of α-synuclein fibrils in the axons of cholinergic enteric neurons. This took place in a time- and, in the case of rotenone, concentration-dependent manner. Rotenone also caused selective necrosis, indicated by increased cellular autofluorescence, of cholinergic enteric neurons, labeled by ChAT-immunoreactivity, also in a concentration-dependent manner. To our knowledge, this is the first report of rotenone causing selective loss of a neurochemical class in the enteric nervous system. Cholinergic enteric neurons may be particularly susceptible to Lewy pathology and degeneration in Parkinson's disease. © 2016 John Wiley & Sons Ltd.

  6. Controlling aggregation propensity in A53T mutant of alpha-synuclein causing Parkinson's disease

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, Sonu; Sarkar, Anita; Sundar, Durai, E-mail: sundar@dbeb.iitd.ac.in

    2009-09-18

    Understanding {alpha}-synuclein in terms of fibrillization, aggregation, solubility and stability is fundamental in Parkinson's disease (PD). The three familial mutations, namely, A30P, E46K and A53T cause PD because the hydrophobic regions in {alpha}-synuclein acquire {beta}-sheet configuration, and have a propensity to fibrillize and form amyloids that cause cytotoxicity and neurodegeneration. On simulating the native form and mutants (A30P, E46K and A53T) of {alpha}-synuclein in water solvent, clear deviations are observed in comparison to the all-helical 1XQ8 PDB structure. We have identified two crucial residues, {sup 40}Val and {sup 74}Val, which play key roles in {beta}-sheet aggregation in the hydrophobic regionsmore » 36-41 and 68-78, respectively, leading to fibrillization and amyloidosis in familial (A53T) PD. We have also identified V40D{sub V}74D, a double mutant of A53T (the most amyloidogenic mutant). The simultaneous introduction of these two mutations in A53T nearly ends its aggregation propensity, increases its solubility and positively enhances its thermodynamic stability.« less

  7. Decreased Expression of α-Synuclein, Nogo-A and UCH-L1 in Patients with Schizophrenia: A Preliminary Serum Study

    PubMed Central

    Cetin, İhsan; Turan, Şenol; Sağlam, Tarık; Yıldız, Nazım; Duran, Alaattin

    2017-01-01

    Objective α-synuclein, Nogo-A and Ubiquitin C-terminal hydrolase L1 (UCH-L1) have neuromodulatory roles for human brain. Therefore, abnormalities of these molecules are associated with neuropsychiatric disorders. Although some serum studies in the other disorders have been made, serum study of α-synuclein, Nogo-A and UCH-L1 is not present in patients with schizophrenia and healthy controls. Therefore, our aim was to compare serum levels of α-synuclein, Nogo-A and UCH-L1 of the patients with schizophrenia and healthy controls. Methods Forty-four patients with schizophrenia who is followed by psychotic disorders unit, and 40 healthy control were included in this study. Socio-demographic form and Positive and Negative Syndrome Scale (PANSS) was applied to patients, and sociodemographic form was applied to control group. Fasting bloods were collected and the serum levels of α-synuclein, Nogo-A and UCH-L1 were measured by ELISA method. Results Serum α-synuclein [patient: 12.73 (5.18–31.84) ng/mL; control: 41.77 (15.12–66.98) ng/mL], Nogo-A [patient: 33.58 (3.09–77.26) ng/mL; control: 286.05 (136.56–346.82) ng/mL] and UCH-L1 [patient: 5.26 (1.64–10.87) ng/mL; control: 20.48 (11.01–20.81) ng/mL] levels of the patients with schizophrenia were significianly lower than healthy controls (p<0.001). Conclusion Our study results added new evidence for explaining the etiopathogenesis of schizophrenia on the basis of neurochemical markers. PMID:28539953

  8. Further association study on dopamine D2 receptor variant S311C in Schizophrenia and affective disorders

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Arinami, Tadao; Hamaguchi, Hideo; Itokawa, Masanari

    The dopamine D2 receptor gene is a candidate gene for schizophrenia because the potency of certain neuroleptics correlates with their affinity for this receptor. Case-control studies in 291 schizophrenics, 78 patients with affective disorders, and 579 controls on an association of a molecular variant of S311C of the dopamine D2 receptor with psychiatric disorders were conducted. The frequency of individuals with S311C was significantly higher in schizophrenics with the absence of negative symptoms (17.1%, P < 0.00001), but similar in schizophrenics with the presence of negative symptoms (5.7%, P = 0.46) when compared with the controls (4.1%). The frequency ofmore » S311C was significantly higher in familiar schizophrenics from one local area but not in those from other areas. It was significant that S311C was frequently present in patients with mood-incongruent psychotic affective disorders (33.3%, P < 0.0001), but not in those with other affective disorders. These data suggest that S311C might be one of the genetic factors for symptomatic dimensions of delusions and hallucinations and might be involved in underlying clinical heterogeneity in schizophrenia and affective disorders. 48 refs., 3 tabs.« less

  9. Parkinson's disease: acid-glucocerebrosidase activity and alpha-synuclein clearance.

    PubMed

    Blanz, Judith; Saftig, Paul

    2016-10-01

    The role of mutations in the gene GBA1 encoding the lysosomal hydrolase β-glucocerebrosidase for the development of synucleinopathies, such as Parkinson's disease and dementia with Lewy bodies, was only very recently uncovered. The knowledge obtained from the study of carriers or patients suffering from Gaucher disease (a common lysosomal storage disorder because of GBA1 mutations) is of particular importance for understanding the role of the enzyme and its catabolic pathway in the development of synucleinopathies. Decreased activity of β-glucocerebrosidase leads to lysosomal dysfunction and the accumulation of its substrate glucosylceramide and related lipid derivatives. Glucosylceramide is suggested to stabilize toxic oligomeric forms of α-synuclein that negatively influence the activity of β-glucocerebrosidase and to partially block export of newly synthesized β-glucocerebrosidase from the endoplasmic reticulum to late endocytic compartments, amplifying the pathological effects of α-synuclein and ultimately resulting in neuronal cell death. This pathogenic molecular feedback loop and most likely other factors (such as impaired endoplasmic reticulum-associated degradation, activation of the unfolded protein response and dysregulation of calcium homeostasis induced by misfolded GC mutants) are involved in shifting the cellular homeostasis from monomeric α-synuclein towards oligomeric neurotoxic and aggregated forms, which contribute to Parkinson's disease progression. From a therapeutic point of view, strategies aiming to increase either the expression, stability or delivery of the β-glucocerebrosidase to lysosomes are likely to decrease the α-synuclein burden and may be useful for an in depth evaluation at the organismal level. Lysosomes are critical for protein and lipid homeostasis. Recent research revealed that dysfunction of this organelle contributes to the development of neurodegenerative diseases such as Parkinson's disease (PD). Mutations in the

  10. Aggresomes formed by alpha-synuclein and synphilin-1 are cytoprotective.

    PubMed

    Tanaka, Mikiei; Kim, Yong Man; Lee, Gwang; Junn, Eunsung; Iwatsubo, Takeshi; Mouradian, M Maral

    2004-02-06

    Lewy bodies (LBs), which are the hallmark pathologic features of Parkinson's disease and of dementia with LBs, have several morphologic and molecular similarities to aggresomes. Whether such cytoplasmic inclusions contribute to neuronal death or protect cells from the toxic effects of misfolded proteins remains controversial. In this report, the role of aggresomes in cell viability was addressed in the context of over-expressing alpha-synuclein and its interacting partner synphilin-1 using engineered 293T cells. Inhibition of proteasome activity elicited the formation of juxtanuclear aggregates with characteristics of aggresomes including immunoreactivity for vimentin, gamma-tubulin, ubiquitin, proteasome subunit, and hsp70. As expected from the properties of aggresomes, the microtubule disrupting agents, vinblastin and nocodazole, markedly prevented the formation of these inclusions. Similar to LBs, the phosphorylated form of alpha-synuclein co-localized in these synphilin-1-containing aggresomes. Although the caspase inhibitor z-VAD-fmk significantly reduced the number of apoptotic cells, it had no impact on the percentage of aggresome-positive cells. Finally, quantitative analysis revealed aggresomes in 60% of nonapoptotic cells but only in 10% of apoptotic cells. Additionally, alpha-synuclein-induced apoptosis was not coupled with increased prevalence of aggresome-bearing cells. Taken together, these observations indicate a disconnection between aggresome formation and apoptosis, and support a protective role for these inclusions from the toxicity associated with the combined over-expression of alpha-synuclein and synphilin-1.

  11. A blood-brain barrier (BBB) disrupter is also a potent α-synuclein (α-syn) aggregation inhibitor: a novel dual mechanism of mannitol for the treatment of Parkinson disease (PD).

    PubMed

    Shaltiel-Karyo, Ronit; Frenkel-Pinter, Moran; Rockenstein, Edward; Patrick, Christina; Levy-Sakin, Michal; Schiller, Abigail; Egoz-Matia, Nirit; Masliah, Eliezer; Segal, Daniel; Gazit, Ehud

    2013-06-14

    The development of disease-modifying therapy for Parkinson disease has been a main drug development challenge, including the need to deliver the therapeutic agents to the brain. Here, we examined the ability of mannitol to interfere with the aggregation process of α-synuclein in vitro and in vivo in addition to its blood-brain barrier-disrupting properties. Using in vitro studies, we demonstrated the effect of mannitol on α-synuclein aggregation. Although low concentration of mannitol inhibited the formation of fibrils, high concentration significantly decreased the formation of tetramers and high molecular weight oligomers and shifted the secondary structure of α-synuclein from α-helical to a different structure, suggesting alternative potential pathways for aggregation. When administered to a Parkinson Drosophila model, mannitol dramatically corrected its behavioral defects and reduced the amount of α-synuclein aggregates in the brains of treated flies. In the mThy1-human α-synuclein transgenic mouse model, a decrease in α-synuclein accumulation was detected in several brain regions following treatment, suggesting that mannitol promotes α-synuclein clearance in the cell bodies. It appears that mannitol has a general neuroprotective effect in the transgenic treated mice, which includes the dopaminergic system. We therefore suggest mannitol as a basis for a dual mechanism therapeutic agent for the treatment of Parkinson disease.

  12. CD24 expression does not affect dopamine neuronal survival in a mouse model of Parkinson's disease.

    PubMed

    Stott, Simon R W; Hayat, Shaista; Carnwath, Tom; Garas, Shaady; Sleeman, Jonathan P; Barker, Roger A

    2017-01-01

    Parkinson's disease (PD) is a progressive neurodegenerative condition that is characterised by the loss of specific populations of neurons in the brain. The mechanisms underlying this selective cell death are unknown but by using laser capture microdissection, the glycoprotein, CD24 has been identified as a potential marker of the populations of cells that are affected in PD. Using in situ hybridization and immunohistochemistry on sections of mouse brain, we confirmed that CD24 is robustly expressed by many of these subsets of cells. To determine if CD24 may have a functional role in PD, we modelled the dopamine cell loss of PD in Cd24 mutant mice using striatal delivery of the neurotoxin 6-OHDA. We found that Cd24 mutant mice have an anatomically normal dopamine system and that this glycoprotein does not modulate the lesion effects of 6-OHDA delivered into the striatum. We then undertook in situ hybridization studies on sections of human brain and found-as in the mouse brain-that CD24 is expressed by many of the subsets of the cells that are vulnerable in PD, but not those of the midbrain dopamine system. Finally, we sought to determine if CD24 is required for the neuroprotective effect of Glial cell-derived neurotrophic factor (GDNF) on the dopaminergic nigrostriatal pathway. Our results indicate that in the absence of CD24, there is a reduction in the protective effects of GDNF on the dopaminergic fibres in the striatum, but no difference in the survival of the cell bodies in the midbrain. While we found no obvious role for CD24 in the normal development and maintenance of the dopaminergic nigrostriatal system in mice, it may have a role in mediating the neuroprotective aspects of GDNF in this system.

  13. A photoaffinity ligand for dopamine D2 receptors: azidoclebopride.

    PubMed

    Niznik, H B; Guan, J H; Neumeyer, J L; Seeman, P

    1985-02-01

    In order to label D2 dopamine receptors selectively and covalently by means of a photosensitive compound, azidoclebopride was synthesized directly from clebopride. The dissociation constant (KD) of clebopride for the D2 dopamine receptor (canine brain striatum) was 1.5 nM, while that for azidoclebopride was 21 nM. The affinities of both clebopride and azidoclebopride were markedly reduced in the absence of sodium chloride. In the presence of ultraviolet light, azidoclebopride inactivated D2 dopamine receptors irreversibly, as indicated by the inability of the receptors to bind [3H]spiperone. Maximal photoinactivation of about 60% of the D2 dopamine receptors occurred at 1 microM azidoclebopride; 30% of the receptors were inactivated at 80 nM azidoclebopride (pseudo-IC50). Dopamine agonists selectively protected the D2 receptors from being inactivated by azidoclebopride, the order of potency being (-)-N-n-propylnorapomorphine greater than apomorphine greater than (+/-)-6,7-dihydroxy-2-aminotetralin greater than (+)-N-n-propylnorapomorphine greater than dopamine greater than noradrenaline greater than serotonin. Similarly, dopaminergic antagonists prevented the photoinactivation of D2 receptors by azidoclebopride with the following order of potency: spiperone greater than (+)-butaclamol greater than haloperidol greater than clebopride greater than (-)-sulpiride greater than (-)-butaclamol. The degree of D2 dopamine receptor photoinduced inactivation by azidoclebopride was not significantly affected by scavengers such as p-aminobenzoic acid and dithiothreitol. Furthermore, irradiation of striatal membranes with a concentration of azidoclebopride sufficient to inactivate dopamine D2 receptors by 60% did not significantly reduce dopamine D1, serotonin (S2), benzodiazepine, alpha 1- or beta-noradrenergic receptors. This study describes the use of a novel and selective photoaffinity ligand for brain dopamine D2 receptors. The molecule, in radiolabeled form, may aid in the

  14. α-Synuclein induced toxicity in brain stem serotonin neurons mediated by an AAV vector driven by the tryptophan hydroxylase promoter.

    PubMed

    Wan, Oi Wan; Shin, Eunju; Mattsson, Bengt; Caudal, Dorian; Svenningsson, Per; Björklund, Anders

    2016-05-23

    We studied the impact of α-synuclein overexpression in brainstem serotonin neurons using a novel vector construct where the expression of human wildtype α-synuclein is driven by the tryptophan hydroxylase promoter, allowing expression of α-synuclein at elevated levels, and with high selectivity, in serotonergic neurons. α-Synuclein induced degenerative changes in axons and dendrites, displaying a distorted appearance, suggesting accumulation and aggregation of α-synuclein as a result of impaired axonal transport, accompanied by a 40% loss of terminals, as assessed in the hippocampus. Tissue levels of serotonin and its major metabolite 5-HIAA remained largely unaltered, and the performance of the α-synuclein overexpressing rats in tests of spatial learning (water maze), anxiety related behavior (elevated plus maze) and depressive-like behavior (forced swim test) was not different from control, suggesting that the impact of the developing axonal pathology on serotonin neurotransmission was relatively mild. Overexpression of α-synuclein in the raphe nuclei, combined with overexpression in basal forebrain cholinergic neurons, resulted in more pronounced axonal pathology and significant impairment in the elevated plus maze. We conclude that α-synuclein pathology in serotonergic or cholinergic neurons alone is not sufficient to impair non-motor behaviors, but that it is their simultaneous involvement that determines severity of such symptoms.

  15. Drp-1 dependent mitochondrial fragmentation and protective autophagy in dopaminergic SH-SY5Y cells overexpressing alpha-synuclein.

    PubMed

    Martinez, Jimena Hebe; Alaimo, Agustina; Gorojod, Roxana Mayra; Porte Alcon, Soledad; Fuentes, Federico; Coluccio Leskow, Federico; Kotler, Mónica Lidia

    2018-04-01

    Parkinson's disease is a neurodegenerative movement disorder caused by the loss of dopaminergic neurons from substantia nigra. It is characterized by the accumulation of aggregated α-synuclein as the major component of the Lewy bodies. Additional common features of this disease are the mitochondrial dysfunction and the activation/inhibition of autophagy both events associated to the intracellular accumulation of α-synuclein. The mechanism by which these events contribute to neural degeneration remains unknown. In the present work we investigated the effect of α-synuclein on mitochondrial dynamics and autophagy/mitophagy in SH-SY5Y cells, an in vitro model of Parkinson disease. We demonstrated that overexpression of wild type α-synuclein causes moderated toxicity, ROS generation and mitochondrial dysfunction. In addition, α-synuclein induces the mitochondrial fragmentation on a Drp-1-dependent fashion. Overexpression of the fusion protein Opa-1 prevented both mitochondrial fragmentation and cytotoxicity. On the other hand, cells expressing α-synuclein showed activated autophagy and particularly mitophagy. Employing a genetic strategy we demonstrated that autophagy is triggered in order to protect cells from α-synuclein-induced cell death. Our results clarify the role of Opa-1 and Drp-1 in mitochondrial dynamics and cell survival, a controversial α-synuclein research issue. The findings presented point to the relevance of mitochondrial homeostasis and autophagy in the pathogenesis of PD. Better understanding of the molecular interaction between these processes could give rise to novel therapeutic methods for PD prevention and amelioration. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. The critical role of Nramp1 in degrading α-synuclein oligomers in microglia under iron overload condition.

    PubMed

    Wu, Kuo-Chen; Liou, Horng-Huei; Kao, Yu-Han; Lee, Chih-Yu; Lin, Chun-Jung

    2017-08-01

    Oligomeric α-synuclein is a key mediator in the pathogenesis of Parkinson's disease (PD) and is mainly cleared by autophagy-lysosomal pathway, whose dysfunction results in the accumulation and cell-to-cell transmission of α-synuclein. In this study, concomitant with the accumulation of iron and oligomeric α-synuclein, higher expression of a lysosomal iron transporter, natural resistance-associated macrophage protein-1 (Nramp1), was observed in microglia in post-mortem striatum of sporadic PD patients. Using Nramp1-deficient macrophage (RAW264.7) and microglial (BV-2) cells as in-vitro models, iron exposure significantly reduced the degradation rate of the administered human α-synuclein oligomers, which can be restored by the expression of the wild-type, but not mutant (D543N), Nramp1. Likewise, under iron overload condition, mice with functional Nramp1 (DBA/2 and C57BL/6 congenic mice carrying functional Nramp1) had a better ability to degrade infused human α-synuclein oligomers than mice with nonfunctional Nramp1 (C57BL/6) in the brain and microglia. The interplay between iron and Nramp1 exhibited parallel effects on the clearance of α-synuclein and the activity of lysosomal cathepsin D in vitro and in vivo. Collectively, these findings suggest that the function of Nramp1 contributes to microglial degradation of oligomeric α-synuclein under iron overload condition and may be implicated in the pathogenesis of PD. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. The Cleavage Effect of Mesenchymal Stem Cell and Its Derived Matrix Metalloproteinase‐2 on Extracellular α‐Synuclein Aggregates in Parkinsonian Models

    PubMed Central

    Oh, Se Hee; Kim, Ha Na; Park, Hyun Jung; Shin, Jin Young; Kim, Dong Yeol

    2016-01-01

    Abstract Ample evidence has suggested that extracellular α‐synuclein aggregates would play key roles in the pathogenesis and progression of Parkinsonian disorders (PDs). In the present study, we investigated whether mesenchymal stem cells (MSCs) and their derived soluble factors could exert neuroprotective effects via proteolysis of extracellular α‐synuclein. When preformed α‐synuclein aggregates were incubated with MSC‐conditioned medium, α‐synuclein aggregates were disassembled, and insoluble and oligomeric forms of α‐synuclein were markedly decreased, thus leading to a significant increase in neuronal viability. In an animal study, MSC or MSC‐conditioned medium treatment decreased the expression of α‐synuclein oligomers and the induction of pathogenic α‐synuclein with an attenuation of apoptotic cell death signaling. Furthermore, we identified that matrix metalloproteinase‐2 (MMP‐2), a soluble factor derived from MSCs, played an important role in the degradation of extracellular α‐synuclein. Our data demonstrated that MSCs and their derived MMP‐2 exert neuroprotective properties through proteolysis of aggregated α‐synuclein in PD‐related microenvironments. Stem Cells Translational Medicine 2017;6:949–961 PMID:28297586

  18. α-Synuclein expression in the mouse cerebellum is restricted to VGluT1 excitatory terminals and is enriched in unipolar brush cells.

    PubMed

    Lee, Sun Kyong; Sillitoe, Roy V; Silva, Coralie; Martina, Marco; Sekerkova, Gabriella

    2015-10-01

    α-Synuclein has a crucial role in synaptic vesicle release and synaptic membrane recycling. Although its general expression pattern has been described in the cerebellum, the precise cerebellar structures where α-synuclein is localized are poorly understood. To address this question, we used α-synuclein immunohistochemistry in adult mice cerebellar sections. We found that α-synuclein labels glutamatergic but not glycinergic and GABAergic synaptic terminals in the molecular and granule cell layers. α-Synuclein was preferentially expressed in parallel and mossy fiber synaptic terminals that also express vesicular glutamate transporter 1 (VGluT1), while it was not detected in VGluT2-positive climbing fibers. α-Synuclein was particularly enriched in lobules IX and X, a region known to contain a high density of unipolar brush cells (UBCs). To elucidate whether the α-synuclein-positive mossy fibers belong to UBCs, we double-labeled cerebellar sections with antibodies to α-synuclein and UBC-type-specific markers (calretinin for type I and metabotropic glutamate receptor 1α (mGluR1α) for type II UBCs) and took advantage of organotypic cerebellar cultures (in which all mossy fibers are UBC axons) and moonwalker mice (in which almost all UBCs are ablated) and found that both type I and type II UBCs express α-synuclein. In moonwalker mutant cerebella, the α-synuclein/VGluT1 immunolabeling showed a dramatic decrease in the vestibulocerebellum that correlated with the absence of UBC. α-Synuclein appears to be an excellent marker for intrinsic mossy fibers of the VGluT1 subset in conjunction with UBCs of both subtypes.

  19. Accumulated α-synuclein affects the progression of GM2 gangliosidoses.

    PubMed

    Suzuki, Kyoko; Yamaguchi, Akira; Yamanaka, Shoji; Kanzaki, Seiichi; Kawashima, Masato; Togo, Takashi; Katsuse, Omi; Koumitsu, Noriko; Aoki, Naoya; Iseki, Eizo; Kosaka, Kenji; Yamaguchi, Kayoko; Hashimoto, Makoto; Aoki, Ichiro; Hirayasu, Yoshio

    2016-10-01

    The accumulation of α-synuclein (ASyn) has been observed in several lysosomal storage diseases (LSDs) but it remains unclear if ASyn accumulation contributes to LSD pathology. ASyn also accumulates in the neurons of Sandhoff disease (SD) patients and SD model mice (Hexb-/- ASyn+/+ mice). SD is a lysosomal storage disorder caused by the absence of a functional β-subunit on the β-hexosaminidase A and B enzymes, which leads to the accumulation of ganglioside in the central nervous system. Here, we explored the role of accumulated ASyn in the progression of Hexb-/- mice by creating a Hexb-/- ASyn-/- double-knockout mice. Our results show that Hexb-/- ASyn-/- mice demonstrated active microglia levels and less dopaminergic neuron loss, without altering the neuronal storage of ganglioside. The autophagy and ubiquitin proteasome pathways are defective in the neurons of Hexb-/- ASyn+/+ mice. In ultrastructural physiological studies, the mitochondria structures look degenerated and dysfunctional. As a result, expression of manganese superoxide dismutase 2 are reduced, and reactive oxygen species-mediated oxidative damage in the neurons of Hexb-/- ASyn+/+ mice. Interestingly, these dysfunctions improved in Hexb-/- ASyn-/- mice. But any clinical improvement were hardly observed in Hexb-/- ASyn-/- mice. Taken together, these findings suggest that ASyn accumulation plays an important role in the pathogenesis of neuropathy in SD and other LSDs, and is therefore a target for novel therapies. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Basal ganglia circuit loops, dopamine and motivation: A review and enquiry

    PubMed Central

    Ikemoto, Satoshi; Yang, Chen; Tan, Aaron

    2015-01-01

    Dopamine neurons located in the midbrain play a role in motivation that regulates approach behavior (approach motivation). In addition, activation and inactivation of dopamine neurons regulate mood and induce reward and aversion, respectively. Accumulating evidence suggests that such motivational role of dopamine neurons is not limited to those located in the ventral tegmental area, but also in the substantia nigra. The present paper reviews previous rodent work concerning dopamine’s role in approach motivation and the connectivity of dopamine neurons, and proposes two working models: One concerns the relationship between extracellular dopamine concentration and approach motivation. High, moderate and low concentrations of extracellular dopamine induce euphoric, seeking and aversive states, respectively. The other concerns circuit loops involving the cerebral cortex, basal ganglia, thalamus, epithalamus, and midbrain through which dopaminergic activity alters approach motivation. These models should help to generate hypothesis-driven research and provide insights for understanding altered states associated with drugs of abuse and affective disorders. PMID:25907747

  1. Polo-like Kinase 2 (PLK2) Phosphorylates α-Synuclein at Serine 129 in Central Nervous System*S⃞

    PubMed Central

    Inglis, Kelly J.; Chereau, David; Brigham, Elizabeth F.; Chiou, San-San; Schöbel, Susanne; Frigon, Normand L.; Yu, Mei; Caccavello, Russell J.; Nelson, Seth; Motter, Ruth; Wright, Sarah; Chian, David; Santiago, Pamela; Soriano, Ferdie; Ramos, Carla; Powell, Kyle; Goldstein, Jason M.; Babcock, Michael; Yednock, Ted; Bard, Frederique; Basi, Guriqbal S.; Sham, Hing; Chilcote, Tamie J.; McConlogue, Lisa; Griswold-Prenner, Irene; Anderson, John P.

    2009-01-01

    Several neurological diseases, including Parkinson disease and dementia with Lewy bodies, are characterized by the accumulation of α-synuclein phosphorylated at Ser-129 (p-Ser-129). The kinase or kinases responsible for this phosphorylation have been the subject of intense investigation. Here we submit evidence that polo-like kinase 2 (PLK2, also known as serum-inducible kinase or SNK) is a principle contributor to α-synuclein phosphorylation at Ser-129 in neurons. PLK2 directly phosphorylates α-synuclein at Ser-129 in an in vitro biochemical assay. Inhibitors of PLK kinases inhibited α-synuclein phosphorylation both in primary cortical cell cultures and in mouse brain in vivo. Finally, specific knockdown of PLK2 expression by transduction with short hairpin RNA constructs or by knock-out of the plk2 gene reduced p-Ser-129 levels. These results indicate that PLK2 plays a critical role in α-synuclein phosphorylation in central nervous system. PMID:19004816

  2. Biophysics of α-synuclein membrane interactions.

    PubMed

    Pfefferkorn, Candace M; Jiang, Zhiping; Lee, Jennifer C

    2012-02-01

    Membrane proteins participate in nearly all cellular processes; however, because of experimental limitations, their characterization lags far behind that of soluble proteins. Peripheral membrane proteins are particularly challenging to study because of their inherent propensity to adopt multiple and/or transient conformations in solution and upon membrane association. In this review, we summarize useful biophysical techniques for the study of peripheral membrane proteins and their application in the characterization of the membrane interactions of the natively unfolded and Parkinson's disease (PD) related protein, α-synuclein (α-syn). We give particular focus to studies that have led to the current understanding of membrane-bound α-syn structure and the elucidation of specific membrane properties that affect α-syn-membrane binding. Finally, we discuss biophysical evidence supporting a key role for membranes and α-syn in PD pathogenesis. This article is part of a Special Issue entitled: Membrane protein structure and function. Copyright © 2011. Published by Elsevier B.V.

  3. A53T-α-synuclein overexpression in murine locus coeruleus induces Parkinson's disease-like pathology in neurons and glia.

    PubMed

    Henrich, Martin Timo; Geibl, Fanni Fruzsina; Lee, Bolam; Chiu, Wei-Hua; Koprich, James Benjamin; Brotchie, Jonathan Michael; Timmermann, Lars; Decher, Niels; Matschke, Lina Anita; Oertel, Wolfgang Hermann

    2018-05-10

    Degeneration of noradrenergic locus coeruleus neurons occurs during the prodromal phase of Parkinson's disease and contributes to a variety of non-motor symptoms, e.g. depression, anxiety and REM sleep behavior disorder. This study was designed to establish the first locus coeruleus α-synucleinopathy mouse model, which should provide sufficient information about the time-course of noradrenergic neurodegeneration, replicate cardinal histopathological features of the human Parkinson's disease neuropathology and finally lead to robust histological markers, which are sufficient to assess the pathological changes in a quantitative and qualitative way. We show that targeted viral vector-mediated overexpression of human mutant A53T-α-synuclein in vivo in locus coeruleus neurons of wild-type mice resulted in progressive noradrenergic neurodegeneration over a time frame of 9 weeks. Observed neuronal cell loss was accompanied by progressive α-synuclein phosphorylation, formation of proteinase K-resistant α-synuclein-aggregates, accumulation of Ubi-1- and p62-positive inclusions in microglia and induction of progressive micro- and astrogliosis. Apart from this local pathology, abundant α-synuclein-positive axons were found in locus coeruleus output regions, indicating rapid anterograde axonal transport of A53T-α-synuclein. Taken together, we present the first model of α-synucleinopathy in the murine locus coeruleus, replicating essential morphological features of human Parkinson's disease pathology. This new model may contribute to the research on prodromal Parkinson's disease, in respect to pathophysiology and the development of disease-modifying therapy.

  4. Structural basis of membrane disruption and cellular toxicity by α-synuclein oligomers.

    PubMed

    Fusco, Giuliana; Chen, Serene W; Williamson, Philip T F; Cascella, Roberta; Perni, Michele; Jarvis, James A; Cecchi, Cristina; Vendruscolo, Michele; Chiti, Fabrizio; Cremades, Nunilo; Ying, Liming; Dobson, Christopher M; De Simone, Alfonso

    2017-12-15

    Oligomeric species populated during the aggregation process of α-synuclein have been linked to neuronal impairment in Parkinson's disease and related neurodegenerative disorders. By using solution and solid-state nuclear magnetic resonance techniques in conjunction with other structural methods, we identified the fundamental characteristics that enable toxic α-synuclein oligomers to perturb biological membranes and disrupt cellular function; these include a highly lipophilic element that promotes strong membrane interactions and a structured region that inserts into lipid bilayers and disrupts their integrity. In support of these conclusions, mutations that target the region that promotes strong membrane interactions by α-synuclein oligomers suppressed their toxicity in neuroblastoma cells and primary cortical neurons. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  5. α-synuclein expression in the mouse cerebellum is restricted to VGluT1 excitatory terminals and is enriched in unipolar brush cells

    PubMed Central

    Lee, Sun Kyong; Sillitoe, Roy V.; Silva, Coralie; Martina, Marco; Sekerkova, Gabriella

    2015-01-01

    α-synuclein has a crucial role in synaptic vesicle release and synaptic membrane recycling. Although its general expression pattern has been described in the cerebellum, the precise cerebellar structures where α-synuclein is localized are poorly understood. To address this question, we used α-synuclein immunohistochemistry in adult mice cerebellar sections. We found that α-synuclein labels glutamatergic but not glycinergic and GABAergic synaptic terminals in the molecular and granule cell layers. α-synuclein was preferentially expressed in parallel and mossy fiber synaptic terminals that also express vesicular glutamate transporter 1 (VGluT1) while it was not detected in VGluT2-positive climbing fibers. α-synuclein was particularly enriched in lobules IX and X, a region known to contain high density of unipolar brush cells (UBCs). To elucidate whether the α-synuclein-positive mossy fibers belong to UBCs, we double labeled cerebellar sections with antibodies to α-synuclein and UBCs type specific markers(calretinin for type I and metabotropic glutamate receptor 1α (mGluR1α) for type II UBCs), and took advantage of organotypic cerebellar cultures (in which all mossy fibers are UBC axons) and moonwalker mice (in which almost all UBCs are ablated) and found that both type I and type II UBCs express α-synuclein. In moonwalker mutant cerebella, the α-synuclein/VGluT1 immunolabeling showed dramatic decrease in the vestibulocerebellum that correlated with the absence of UBC. α-synuclein appears to be an excellent marker for intrinsic mossy fibers of the VGluT1 subset in conjunction with UBCs of both subtypes. PMID:25917213

  6. Neurogranin binds α-synuclein in the human superior temporal cortex and interaction is decreased in Parkinson's disease.

    PubMed

    Koob, Andrew O; Shaked, Gideon M; Bender, Andreas; Bisquertt, Alejandro; Rockenstein, Edward; Masliah, Eliezer

    2014-12-03

    Neurogranin is a calmodulin binding protein that has been implicated in learning and memory, long-term potentiation and synaptic plasticity. Neurons expressing neurogranin in the cortex degenerate in late stages of Parkinson's disease with widespread α-synuclein pathology. While analyzing neurogranin gene expression levels through rtPCR in brains of mouse models overexpressing human α-synuclein, we found levels were elevated 2.5 times when compared to nontransgenic animals. Immunohistochemistry in the cortex revealed colocalization between α-synuclein and neurogranin in mouse transgenics when compared to control mice. Coimmunoprecipitation studies in the superior temporal cortex in humans confirmed interaction between α-synuclein and neurogranin, and decreased interaction between α-synuclein and neurogranin was noticed in patients diagnosed with Parkinson's disease when compared to normal control brains. Additionally, phosphorylated neurogranin levels were also decreased in the human superior temporal cortex in patients diagnosed with Parkinson's disease and patients diagnosed with dementia with Lewy bodies. Here, we show for the first time that neurogranin binds to α-synuclein in the human cortex, and this interaction decreases in Parkinson's disease along with the phosphorylation of neurogranin, a molecular process thought to be involved in learning and memory. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Sleep Dysfunction and EEG Alterations in Mice Overexpressing Alpha-Synuclein

    PubMed Central

    McDowell, Kimberly A.; Shin, David; Roos, Kenneth P.; Chesselet, Marie-Françoise

    2018-01-01

    Background: Sleep disruptions occur early and frequently in Parkinson’s disease (PD). PD patients also show a slowing of resting state activity. Alpha-synuclein is causally linked to PD and accumulates in sleep-related brain regions. While sleep problems occur in over 75% of PD patients and severely impact the quality of life of patients and caregivers, their study is limited by a paucity of adequate animal models. Objective: The objective of this study was to determine whether overexpression of wildtype alpha-synuclein could lead to alterations in sleep patterns reminiscent of those observed in PD by measuring sleep/wake activity with rigorous quantitative methods in a well-characterized genetic mouse model. Methods: At 10 months of age, mice expressing human wildtype alpha-synuclein under the Thy-1 promoter (Thy1-aSyn) and wildtype littermates underwent the subcutaneous implantation of a telemetry device (Data Sciences International) for the recording of electromyograms (EMG) and electroencephalograms (EEG) in freely moving animals. Surgeries and data collection were performed without knowledge of mouse genotype. Results: Thy1-aSyn mice showed increased non-rapid eye movement sleep during their quiescent phase, increased active wake during their active phase, and decreased rapid eye movement sleep over a 24-h period, as well as a shift in the density of their EEG power spectra toward lower frequencies with a significant decrease in gamma power during wakefulness. Conclusions: Alpha-synuclein overexpression in mice produces sleep disruptions and altered oscillatory EEG activity reminiscent of PD, and this model provides a novel platform to assess mechanisms and therapeutic strategies for sleep dysfunction in PD. PMID:24867919

  8. Cold denaturation of α-synuclein amyloid fibrils.

    PubMed

    Ikenoue, Tatsuya; Lee, Young-Ho; Kardos, József; Saiki, Miyu; Yagi, Hisashi; Kawata, Yasushi; Goto, Yuji

    2014-07-21

    Although amyloid fibrils are associated with numerous pathologies, their conformational stability remains largely unclear. Herein, we probe the thermal stability of various amyloid fibrils. α-Synuclein fibrils cold-denatured to monomers at 0-20 °C and heat-denatured at 60-110 °C. Meanwhile, the fibrils of β2-microglobulin, Alzheimer's Aβ1-40/Aβ1-42 peptides, and insulin exhibited only heat denaturation, although they showed a decrease in stability at low temperature. A comparison of structural parameters with positive enthalpy and heat capacity changes which showed opposite signs to protein folding suggested that the burial of charged residues in fibril cores contributed to the cold denaturation of α-synuclein fibrils. We propose that although cold-denaturation is common to both native proteins and misfolded fibrillar states, the main-chain dominated amyloid structures may explain amyloid-specific cold denaturation arising from the unfavorable burial of charged side-chains in fibril cores. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. HMGB1 promotes the starvation-induced autophagic degradation of α-synuclein in SH-SY5Y cells Atg 5-dependently.

    PubMed

    Guan, Yi; Li, Yiping; Zhao, Gang; Li, Yunqian

    2018-06-01

    Impaired autophagic clearance of aggregated α-synuclein is considered as one of key mechanisms underlining Parkinson disease (PD). High-mobility group protein B1 (HMGB1) has recently been demonstrated to mediate persistent neuroinflammation and consequent progressive neurodegeneration by promoting multiple inflammatory and neurotoxic factors. In this study, we examined the influence of the overexpression of wild-type (WT) and mutant-type (MT, A53T and A30P) α-synuclein on the autophagy in neuroblastoma SH-SY5Y cells under starvation, and then investigated the regulation of endogenous HMGB1 on the α-synuclein degradation and on the starvation-induced autophagy in the α-synuclein-overexpressed SH-SY5Y cells. It was demonstrated that the overexpression of WT or MT α-synuclein significantly downregulated the starvation-induced conversion of LC3I to LC3II and autophagy protein (Atg) 5 expression, whereas markedly inhibited the starvation-downregulated mTOR in SH-SY5Y cells. On the other side, the lentivirus-mediated upregulation of endogenous HMGB1 promoted the degradation of WT or MT α-synuclein in SH-SY5Y cells autophagy-dependently via promoting Atg 5, but not mTOR, the Atg 5 knockdown downregulated the HMGB1-mediated promotion to α-synuclein degeneration. Thus, we concluded that α-synuclein inhibited the starvation-induced autophagy in neuroblastoma SH-SY5Y cells via inhibiting the mTOR/Atg 5 signaling. However, the endogenous HMGB1 promoted the autophagic degradation of α-synuclein via the Atg 5-dependent autophagy-initiation pathway, implying the protective role of endogenous HMGB1 in the neuroblastoma cells against the α-synuclein accumulation. Copyright © 2018. Published by Elsevier Inc.

  10. Mutant Alpha-Synuclein Causes Age-Dependent Neuropathology in Monkey Brain

    PubMed Central

    Yang, Weili; Wang, Guohao; Wang, Chuan-En; Guo, Xiangyu; Yin, Peng; Gao, Jinquan; Tu, Zhuchi; Wang, Zhengbo; Wu, Jing; Hu, Xintian; Li, Shihua

    2015-01-01

    Parkinson's disease (PD) is an age-dependent neurodegenerative disease that often occurs in those over age 60. Although rodents and small animals have been used widely to model PD and investigate its pathology, their short life span makes it difficult to assess the aging-related pathology that is likely to occur in PD patient brains. Here, we used brain tissues from rhesus monkeys at 2–3, 7–8, and >15 years of age to examine the expression of Parkin, PINK1, and α-synuclein, which are known to cause PD via loss- or gain-of-function mechanisms. We found that α-synuclein is increased in the older monkey brains, whereas Parkin and PINK1 are decreased or remain unchanged. Because of the gain of toxicity of α-synuclein, we performed stereotaxic injection of lentiviral vectors expressing mutant α-synuclein (A53T) into the substantia nigra of monkeys and found that aging also increases the accumulation of A53T in neurites and its associated neuropathology. A53T also causes more extensive reactive astrocytes and axonal degeneration in monkey brain than in mouse brain. Using monkey brain tissues, we found that A53T interacts with neurofascin, an adhesion molecule involved in axon subcellular targeting and neurite outgrowth. Aged monkey brain tissues show an increased interaction of neurofascin with A53T. Overexpression of A53T causes neuritic toxicity in cultured neuronal cells, which can be attenuated by transfected neurofascin. These findings from nonhuman primate brains reveal age-dependent pathological and molecular changes that could contribute to the age-dependent neuropathology in PD. PMID:26019347

  11. Mutant alpha-synuclein causes age-dependent neuropathology in monkey brain.

    PubMed

    Yang, Weili; Wang, Guohao; Wang, Chuan-En; Guo, Xiangyu; Yin, Peng; Gao, Jinquan; Tu, Zhuchi; Wang, Zhengbo; Wu, Jing; Hu, Xintian; Li, Shihua; Li, Xiao-Jiang

    2015-05-27

    Parkinson's disease (PD) is an age-dependent neurodegenerative disease that often occurs in those over age 60. Although rodents and small animals have been used widely to model PD and investigate its pathology, their short life span makes it difficult to assess the aging-related pathology that is likely to occur in PD patient brains. Here, we used brain tissues from rhesus monkeys at 2-3, 7-8, and >15 years of age to examine the expression of Parkin, PINK1, and α-synuclein, which are known to cause PD via loss- or gain-of-function mechanisms. We found that α-synuclein is increased in the older monkey brains, whereas Parkin and PINK1 are decreased or remain unchanged. Because of the gain of toxicity of α-synuclein, we performed stereotaxic injection of lentiviral vectors expressing mutant α-synuclein (A53T) into the substantia nigra of monkeys and found that aging also increases the accumulation of A53T in neurites and its associated neuropathology. A53T also causes more extensive reactive astrocytes and axonal degeneration in monkey brain than in mouse brain. Using monkey brain tissues, we found that A53T interacts with neurofascin, an adhesion molecule involved in axon subcellular targeting and neurite outgrowth. Aged monkey brain tissues show an increased interaction of neurofascin with A53T. Overexpression of A53T causes neuritic toxicity in cultured neuronal cells, which can be attenuated by transfected neurofascin. These findings from nonhuman primate brains reveal age-dependent pathological and molecular changes that could contribute to the age-dependent neuropathology in PD. Copyright © 2015 the authors 0270-6474/15/358345-14$15.00/0.

  12. Nigrostriatal neuronal death following chronic dichlorvos exposure: crosstalk between mitochondrial impairments, α synuclein aggregation, oxidative damage and behavioral changes

    PubMed Central

    2010-01-01

    Background In recent years, several lines of evidence have shown an increase in Parkinson's disease prevalence in rural environments where pesticides are heavily used. Although, the underlying mechanism for neuronal degeneration in sporadic PD remains unknown, mitochondrial dysfunction, oxidative stress and proteasomal dysfunction are proposed as contributing factors. In this study rats were chronically and continuously exposed to the pesticide, dichlorvos to identify the molecular mechanism of nigrostaital neuronal degeneration. Result Chronic dichlorvos exposure (2.50 mg/kg b.wt.s.c/daily for 12 weeks) caused nigrostriatal dopaminergic degeneration. The degenerative changes were accompanied by a loss of 60-80% of the nigral dopamine neurons and 60-70% reduction in striatal dopamine and tyrosine hydroxylase levels. Dichlorvos exposed animals also showed α -synuclein and ubiquitin positive inclusions along with swollen, dystrophic neurites and mitochondrial abnormalities like decreased complex I&IV activities, increased mitochondrial size, axonal degeneration and presence of electron dense perinuclear cytoplasmic inclusions in the substantia nigra of rats. These animals also showed evidence of oxidative stress, including increased mitochondrial ROS levels, decreased MnSOD activity and increased lipid peroxidation. Measurable impairments in neurobehavioral indices were also observed. Notable exacerbations in motor impairments, open field and catalepsy were also evident in dichlorvos exposed animals. Conclusion All these findings taken together indicate that chronic dichlorvos exposure may cause nigrostaital neurodegenaration and significant behavioral impairments. PMID:21073741

  13. Parkinson disease.

    PubMed

    Poewe, Werner; Seppi, Klaus; Tanner, Caroline M; Halliday, Glenda M; Brundin, Patrik; Volkmann, Jens; Schrag, Anette-Eleonore; Lang, Anthony E

    2017-03-23

    Parkinson disease is the second-most common neurodegenerative disorder that affects 2-3% of the population ≥65 years of age. Neuronal loss in the substantia nigra, which causes striatal dopamine deficiency, and intracellular inclusions containing aggregates of α-synuclein are the neuropathological hallmarks of Parkinson disease. Multiple other cell types throughout the central and peripheral autonomic nervous system are also involved, probably from early disease onwards. Although clinical diagnosis relies on the presence of bradykinesia and other cardinal motor features, Parkinson disease is associated with many non-motor symptoms that add to overall disability. The underlying molecular pathogenesis involves multiple pathways and mechanisms: α-synuclein proteostasis, mitochondrial function, oxidative stress, calcium homeostasis, axonal transport and neuroinflammation. Recent research into diagnostic biomarkers has taken advantage of neuroimaging in which several modalities, including PET, single-photon emission CT (SPECT) and novel MRI techniques, have been shown to aid early and differential diagnosis. Treatment of Parkinson disease is anchored on pharmacological substitution of striatal dopamine, in addition to non-dopaminergic approaches to address both motor and non-motor symptoms and deep brain stimulation for those developing intractable L-DOPA-related motor complications. Experimental therapies have tried to restore striatal dopamine by gene-based and cell-based approaches, and most recently, aggregation and cellular transport of α-synuclein have become therapeutic targets. One of the greatest current challenges is to identify markers for prodromal disease stages, which would allow novel disease-modifying therapies to be started earlier.

  14. Rasagiline protects against alpha-synuclein induced sensitivity to oxidative stress in dopaminergic cells

    PubMed Central

    Chau, K.Y.; Cooper, J.M.; Schapira, A.H.V.

    2010-01-01

    Rasagiline is a propargylamine and irreversible monoamine oxidase (MAO) B inhibitor used for the treatment of Parkinson's disease (PD). It has demonstrated neuroprotective properties in laboratory studies. Current concepts of PD aetiopathogenesis include the role of alpha-synuclein, protein aggregation, free radical metabolism and mitochondrial dysfunction in contributing to cell death. We have used a combination of alpha-synuclein and free radical mediated toxicity in a dopaminergic cell line to provide a model of nigral toxicity in order to investigate the potential molecular mechanisms that mediate rasagiline protection. We demonstrate that rasagiline protects against cell death induced by the combination of free radicals generated by paraquat and either wild-type or A53T mutant alpha-synuclein over-expression. This protection was associated with a reduction in caspase 3 activation, a reduction in superoxide generation and a trend to ameliorate the fall in mitochondrial membrane potential. Rasagiline induced an increase in cellular glutathione levels. The results support a role for rasagiline in protecting dopaminergic cells against free radical mediated damage and apoptosis in the presence of alpha-synuclein over-expression. The data are of relevance to the interpretation of the potential mechanisms of action of rasagiline in explaining the results of disease modification trials in PD. PMID:20624440

  15. Repurposing doxycycline for synucleinopathies: remodelling of α-synuclein oligomers towards non-toxic parallel beta-sheet structured species

    PubMed Central

    González-Lizárraga, Florencia; Socías, Sergio B.; Ávila, César L.; Torres-Bugeau, Clarisa M.; Barbosa, Leandro R. S.; Binolfi, Andres; Sepúlveda-Díaz, Julia E.; Del-Bel, Elaine; Fernandez, Claudio O.; Papy-Garcia, Dulce; Itri, Rosangela; Raisman-Vozari, Rita; Chehín, Rosana N.

    2017-01-01

    Synucleinophaties are progressive neurodegenerative disorders with no cure to date. An attractive strategy to tackle this problem is repurposing already tested safe drugs against novel targets. In this way, doxycycline prevents neurodegeneration in Parkinson models by modulating neuroinflammation. However, anti-inflammatory therapy per se is insufficient to account for neuroprotection. Herein we characterise novel targets of doxycycline describing the structural background supporting its effectiveness as a neuroprotector at subantibiotic doses. Our results show that doxycycline reshapes α-synuclein oligomers into off-pathway, high-molecular-weight species that do not evolve into fibrils. Off-pathway species present less hydrophobic surface than on-pathway oligomers and display different β-sheet structural arrangement. These structural changes affect the α-synuclein ability to destabilize biological membranes, cell viability, and formation of additional toxic species. Altogether, these mechanisms could act synergically giving novel targets for repurposing this drug. PMID:28155912

  16. Is trehalose an autophagic inducer? Unraveling the roles of non-reducing disaccharides on autophagic flux and alpha-synuclein aggregation.

    PubMed

    Yoon, Ye-Seul; Cho, Eun-Duk; Jung Ahn, Woo; Won Lee, Kyung; Lee, Seung-Jae; Lee, He-Jin

    2017-10-05

    Autophagy is a pivotal intracellular process by which cellular macromolecules are degraded upon various stimuli. A failure in the degradation of autophagic substrates such as impaired organelles and protein aggregates leads to their accumulations, which are characteristics of many neurodegenerative diseases. Pharmacological activation of autophagy has thus been considered a prospective therapeutic approach for treating neurodegenerative diseases. Among a number of autophagy-inducing agents, trehalose has received attention for its beneficial effects in different disease models of neurodegeneration. However, how trehalose promotes autophagy has not been fully revealed. We investigated the influence of trehalose and other disaccharides upon autophagic flux and aggregation of α-synuclein, a protein linked to Parkinson's disease. In differentiated human neuroblastoma and primary rat cortical neuron culture models, treatment with trehalose and other disaccharides resulted in accumulation of lipidated LC3 (LC3-II), p62, and autophagosomes, whereas it decreased autolysosomes. On the other hand, addition of Bafilomycin A1 to trehalose treatments had relatively marginal effect, an indicative of autophagic flux blockage. In concordance with these results, the cells treated with trehalose exhibited an incremental tendency in α-synuclein aggregation. Secretion of α-synuclein was also elevated in the culture medium upon trehalose treatment, thereby significantly increasing intercellular transmission of this protein. Despite the substantial increase in α-synuclein aggregation, which normally leads to cell death, cell viability was not affected upon treatment with trehalose, suggesting an autophagy-independent protective function of trehalose against protein aggregates. This study demonstrates that, although trehalose has been widely considered an autophagic inducer, it may be actually a potent blocker of the autophagic flux.

  17. THE MYSTERIOUS MOTIVATIONAL FUNCTIONS OF MESOLIMBIC DOPAMINE

    PubMed Central

    Salamone, John D.; Correa, Mercè

    2012-01-01

    Summary Nucleus accumbens dopamine is known to play a role in motivational processes, and dysfunctions of mesolimbic dopamine may contribute to motivational symptoms of depression and other disorders, as well as features of substance abuse. Although it has become traditional to label dopamine neurons as “reward” neurons, this is an over-generalization, and it is important to distinguish between aspects of motivation that are differentially affected by dopaminergic manipulations. For example, accumbens dopamine does not mediate primary food motivation or appetite, but is involved in appetitive and aversive motivational processes including behavioral activation, exertion of effort, approach behavior, sustained task engagement, Pavlovian processes and instrumental learning. In this review, we discuss the complex roles of dopamine in behavioral functions related to motivation. PMID:23141060

  18. Convergence of pathology in dementia with Lewy bodies and Alzheimer's disease: a role for the novel interaction of alpha-synuclein and presenilin 1 in disease.

    PubMed

    Winslow, Ashley R; Moussaud, Simon; Zhu, Liya; Post, Kathryn L; Post, Katherine L; Dickson, Dennis W; Berezovska, Oksana; McLean, Pamela J

    2014-07-01

    A growing number of PSEN1 mutations have been associated with dementia with Lewy bodies and familial Alzheimer's disease with concomitant α-synuclein pathology. The objective of this study was to determine if PSEN1 plays a direct role in the development of α-synuclein pathology in these diseases. Using mass spectrometry, immunoelectron microscopy and fluorescence lifetime image microscopy based on Forster resonance energy transfer (FLIM-FRET) we identified α-synuclein as a novel interactor of PSEN1 in wild-type mouse brain tissue. The interaction of α-synuclein with PSEN1 was detected in post-mortem brain tissue from cognitively normal cases and was significantly increased in tissue from cases with dementia with Lewy bodies and familial Alzheimer's disease associated with known PSEN1 mutations. We confirmed an increased interaction of PSEN1 and α-synuclein in cell lines expressing well characterized familial Alzheimer's disease PSEN1 mutations, L166P and delta exon 9, and demonstrated that PSEN1 mutations associate with increased membrane association and accumulation of α-synuclein. Our data provides evidence of a molecular interaction of PSEN1 and α-synuclein that may explain the clinical and pathophysiological overlap seen in synucleinopathies, including Parkinson's disease, dementia with Lewy bodies, and some forms of Alzheimer's disease. © The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Presence and function of dopamine transporter (DAT) in stallion sperm: dopamine modulates sperm motility and acrosomal integrity.

    PubMed

    Urra, Javier A; Villaroel-Espíndola, Franz; Covarrubias, Alejandra A; Rodríguez-Gil, Joan Enric; Ramírez-Reveco, Alfredo; Concha, Ilona I

    2014-01-01

    Dopamine is a catecholamine with multiple physiological functions, playing a key role in nervous system; however its participation in reproductive processes and sperm physiology is controversial. High dopamine concentrations have been reported in different portions of the feminine and masculine reproductive tract, although the role fulfilled by this catecholamine in reproductive physiology is as yet unknown. We have previously shown that dopamine type 2 receptor is functional in boar sperm, suggesting that dopamine acts as a physiological modulator of sperm viability, capacitation and motility. In the present study, using immunodetection methods, we revealed the presence of several proteins important for the dopamine uptake and signalling in mammalian sperm, specifically monoamine transporters as dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters in equine sperm. We also demonstrated for the first time in equine sperm a functional dopamine transporter using 4-[4-(Dimethylamino)styryl]-N-methylpyridinium iodide (ASP(+)), as substrate. In addition, we also showed that dopamine (1 mM) treatment in vitro, does not affect sperm viability but decreases total and progressive sperm motility. This effect is reversed by blocking the dopamine transporter with the selective inhibitor vanoxerine (GBR12909) and non-selective inhibitors of dopamine reuptake such as nomifensine and bupropion. The effect of dopamine in sperm physiology was evaluated and we demonstrated that acrosome integrity and thyrosine phosphorylation in equine sperm is significantly reduced at high concentrations of this catecholamine. In summary, our results revealed the presence of monoamine transporter DAT, NET and SERT in equine sperm, and that the dopamine uptake by DAT can regulate sperm function, specifically acrosomal integrity and sperm motility.

  20. Presence and Function of Dopamine Transporter (DAT) in Stallion Sperm: Dopamine Modulates Sperm Motility and Acrosomal Integrity

    PubMed Central

    Covarrubias, Alejandra A.; Rodríguez-Gil, Joan Enric; Ramírez-Reveco, Alfredo; Concha, Ilona I.

    2014-01-01

    Dopamine is a catecholamine with multiple physiological functions, playing a key role in nervous system; however its participation in reproductive processes and sperm physiology is controversial. High dopamine concentrations have been reported in different portions of the feminine and masculine reproductive tract, although the role fulfilled by this catecholamine in reproductive physiology is as yet unknown. We have previously shown that dopamine type 2 receptor is functional in boar sperm, suggesting that dopamine acts as a physiological modulator of sperm viability, capacitation and motility. In the present study, using immunodetection methods, we revealed the presence of several proteins important for the dopamine uptake and signalling in mammalian sperm, specifically monoamine transporters as dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters in equine sperm. We also demonstrated for the first time in equine sperm a functional dopamine transporter using 4-[4-(Dimethylamino)styryl]-N-methylpyridinium iodide (ASP+), as substrate. In addition, we also showed that dopamine (1 mM) treatment in vitro, does not affect sperm viability but decreases total and progressive sperm motility. This effect is reversed by blocking the dopamine transporter with the selective inhibitor vanoxerine (GBR12909) and non-selective inhibitors of dopamine reuptake such as nomifensine and bupropion. The effect of dopamine in sperm physiology was evaluated and we demonstrated that acrosome integrity and thyrosine phosphorylation in equine sperm is significantly reduced at high concentrations of this catecholamine. In summary, our results revealed the presence of monoamine transporter DAT, NET and SERT in equine sperm, and that the dopamine uptake by DAT can regulate sperm function, specifically acrosomal integrity and sperm motility. PMID:25402186

  1. A Novel Hsp90 Inhibitor Activates Compensatory Heat Shock Protein Responses and Autophagy and Alleviates Mutant A53T α-Synuclein Toxicity

    PubMed Central

    Xiong, Rui; Zhou, Wenbo; Siegel, David; Kitson, Russell R. A.; Freed, Curt R.; Moody, Christopher J.

    2015-01-01

    A potential cause of neurodegenerative diseases, including Parkinson’s disease (PD), is protein misfolding and aggregation that in turn leads to neurotoxicity. Targeting Hsp90 is an attractive strategy to halt neurodegenerative diseases, and benzoquinone ansamycin (BQA) Hsp90 inhibitors such as geldanamycin (GA) and 17-(allylamino)-17-demethoxygeldanamycin have been shown to be beneficial in mutant A53T α-synuclein PD models. However, current BQA inhibitors result in off-target toxicities via redox cycling and/or arylation of nucleophiles at the C19 position. We developed novel 19-substituted BQA (19BQA) as a means to prevent arylation. In this study, our data demonstrated that 19-phenyl-GA, a lead 19BQA in the GA series, was redox stable and exhibited little toxicity relative to its parent quinone GA in human dopaminergic SH-SY5Y cells as examined by oxygen consumption, trypan blue, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT), and apoptosis assays. Meanwhile, 19-phenyl-GA retained the ability to induce autophagy and potentially protective heat shock proteins (HSPs) such as Hsp70 and Hsp27. We found that transduction of A53T, but not wild type (WT) α-synuclein, induced toxicity in SH-SY5Y cells. 19-Phenyl-GA decreased oligomer formation and toxicity of A53T α-synuclein in transduced cells. Mechanistic studies indicated that mammalian target of rapamycin (mTOR)/p70 ribosomal S6 kinase signaling was activated by A53T but not WT α-synuclein, and 19-phenyl-GA decreased mTOR activation that may be associated with A53T α-synuclein toxicity. In summary, our results indicate that 19BQAs such as 19-phenyl-GA may provide a means to modulate protein-handling systems including HSPs and autophagy, thereby reducing the aggregation and toxicity of proteins such as mutant A53T α-synuclein. PMID:26405178

  2. Convergence of pathology in dementia with Lewy bodies and Alzheimer’s disease: a role for the novel interaction of alpha-synuclein and presenilin 1 in disease

    PubMed Central

    Winslow, Ashley R.; Moussaud, Simon; Zhu, Liya; Post, Katherine L.; Dickson, Dennis W.

    2014-01-01

    A growing number of PSEN1 mutations have been associated with dementia with Lewy bodies and familial Alzheimer’s disease with concomitant α-synuclein pathology. The objective of this study was to determine if PSEN1 plays a direct role in the development of α-synuclein pathology in these diseases. Using mass spectrometry, immunoelectron microscopy and fluorescence lifetime image microscopy based on Forster resonance energy transfer (FLIM-FRET) we identified α-synuclein as a novel interactor of PSEN1 in wild-type mouse brain tissue. The interaction of α-synuclein with PSEN1 was detected in post-mortem brain tissue from cognitively normal cases and was significantly increased in tissue from cases with dementia with Lewy bodies and familial Alzheimer’s disease associated with known PSEN1 mutations. We confirmed an increased interaction of PSEN1 and α-synuclein in cell lines expressing well characterized familial Alzheimer’s disease PSEN1 mutations, L166P and delta exon 9, and demonstrated that PSEN1 mutations associate with increased membrane association and accumulation of α-synuclein. Our data provides evidence of a molecular interaction of PSEN1 and α-synuclein that may explain the clinical and pathophysiological overlap seen in synucleinopathies, including Parkinson’s disease, dementia with Lewy bodies, and some forms of Alzheimer’s disease. PMID:24860142

  3. Late stages of hematopoiesis and B cell lymphopoiesis are regulated by α-synuclein, a key player in Parkinson's disease.

    PubMed

    Xiao, Wenbin; Shameli, Afshin; Harding, Clifford V; Meyerson, Howard J; Maitta, Robert W

    2014-11-01

    α-Synuclein plays a crucial role in Parkinson's disease and dementias defined as synucleinopathies. α-Synuclein is expressed in hematopoietic and immune cells, but its functions in hematopoiesis and immune responses are unknown. We utilized α-synuclein(-/-) (KO) mice to investigate its role in hematopoiesis and B cell lymphopoiesis. We demonstrated hematologic abnormalities including mild anemia, smaller platelets, lymphopenia but relatively normal early hematopoiesis in KO mice compared to wild-type (WT) as measured in hematopoietic stem cells and progenitors of the different cell lineages. However, the absolute number of B220(+)IgM(+) B cells in bone marrow was reduced by 4-fold in KO mice (WT: 104±23×10(5) vs. KO: 27±5×10(5)). B cells were also reduced in KO spleens associated with effacement of splenic and lymph node architecture. KO mice showed reduced total serum IgG but no abnormality in serum IgM was noted. When KO mice were challenged with a T cell-dependent antigen, production of antigen specific IgG1 and IgG2b was abolished, but antigen specific IgM was not different from WT mice. Our study shows hematologic abnormalities including anemia and smaller platelets, reduced B cell lymphopoiesis and defects in IgG production in the absence of α-synuclein. This is the first report to show an important role of α-synuclein late in hematopoiesis, B cell lymphopoiesis and adaptive immune response. Copyright © 2014 Elsevier GmbH. All rights reserved.

  4. Intrinsic Conformational Preferences and Interactions in α-Synuclein Fibrils: Insights from Molecular Dynamics Simulations.

    PubMed

    Ilie, Ioana M; Nayar, Divya; den Otter, Wouter K; van der Vegt, Nico F A; Briels, Wim J

    2018-06-12

    Amyloid formation by the intrinsically disordered α-synuclein protein is the hallmark of Parkinson's disease. We present atomistic Molecular Dynamics simulations of the core of α-synuclein using enhanced sampling techniques to describe the conformational and binding free energy landscapes of fragments implicated in fibril stabilization. The theoretical framework is derived to combine the free energy profiles of the fragments into the reaction free energy of a protein binding to a fibril. Our study shows that individual fragments in solution have a propensity toward attaining non-β conformations, indicating that in a fibril β-strands are stabilized by interactions with other strands. We show that most dimers of hydrogen-bonded fragments are unstable in solution, while hydrogen bonding stabilizes the collective binding of five fragments to the end of a fibril. Hydrophobic effects make further contributions to the stability of fibrils. This study is the first of its kind where structural and binding preferences of the five major fragments of the hydrophobic core of α-synuclein have been investigated. This approach improves sampling of intrinsically disordered proteins, provides information on the binding mechanism between the core sequences of α-synuclein, and enables the parametrization of coarse grained models.

  5. Neurogranin binds α-synuclein in the human superior temporal cortex and interaction is decreased in Parkinson’s disease

    PubMed Central

    Koob, Andrew O.; Shaked, Gideon M.; Bender, Andreas; Bisquertt, Alejandro; Rockenstein, Edward; Masliah, Eliezer

    2016-01-01

    Neurogranin is a calmodulin binding protein that has been implicated in learning and memory, long-term potentiation and synaptic plasticity. Neurons expressing neurogranin in the cortex degenerate in late stages of Parkinson’s disease with widespread α-synuclein pathology. While analyzing neurogranin gene expression levels through rtPCR in brains of mouse models overexpressing human α-synuclein, we found levels were elevated 2.5 times when compared to nontransgenic animals. Immunohistochemistry in the cortex revealed colocalization between α-synuclein and neurogranin in mouse transgenics when compared to control mice. Coimmunoprecipitation studies in the superior temporal cortex in humans confirmed interaction between α-synuclein and neurogranin, and decreased interaction between α-synuclein and neurogranin was noticed in patients diagnosed with Parkinson’s disease when compared to normal control brains. Additionally, phosphorylated neurogranin levels were also decreased in the human superior temporal cortex in patients diagnosed with Parkinson’s disease and patients diagnosed with dementia with Lewy bodies. Here, we show for the first time that neurogranin binds to α-synuclein in the human cortex, and this interaction decreases in Parkinson’s disease along with the phosphorylation of neurogranin, a molecular process thought to be involved in learning and memory. PMID:25446004

  6. Effects of different isoforms of apoE on aggregation of the α-synuclein protein implicated in Parkinson's disease.

    PubMed

    Emamzadeh, Fatemeh Nouri; Aojula, Harmesh; McHugh, Patrick C; Allsop, David

    2016-04-08

    Parkinson's disease is a progressive brain disorder due to the degeneration of dopaminergic neurons in the substantia nigra. The accumulation of aggregated forms of α-synuclein protein into Lewy bodies is one of the characteristic features of this disease although the pathological role of any such protein deposits in causing neurodegeneration remains elusive. Here, the effects of different apolipoprotein E isoforms (apoE2, apoE3, apoE4) on the aggregation of α-synuclein in vitro were examined using thioflavin T assays and also an immunoassay to detect the formation of multimeric forms. Our results revealed that the aggregation of α-synuclein is influenced by apoE concentration. At low concentrations of apoE (<15nM), all of the isoforms were able to increase the aggregation of α-synuclein (50μM), with apoE4 showing the greatest stimulatory effect. This is in contrast to a higher concentration (>15nM) of these isoforms, where a decrease in the aggregation of α-synuclein was noted. The data show that exceptionally low levels of apoE may seed α-syn aggregation, which could potentially lead to the pathogenesis of α-synuclein-induced neurodegeneration. On the other hand, higher levels of apoE could potentially lower the degree of α-synuclein aggregation and confer protection. The differential effects noted with apoE4 could explain why this particular isoform results in an earlier age of onset for Parkinson's disease. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Redox reactions of the α-synuclein-Cu(2+) complex and their effects on neuronal cell viability.

    PubMed

    Wang, Chengshan; Liu, Lin; Zhang, Lin; Peng, Yong; Zhou, Feimeng

    2010-09-21

    α-Synuclein (α-syn), a presynaptic protein believed to play an important role in neuropathology in Parkinson's disease (PD), is known to bind Cu(2+). Cu(2+) has been shown to accelerate the aggregation of α-syn to form various toxic aggregates in vitro. Copper is also a redox-active metal whose complexes with amyloidogenic proteins/peptides have been linked to oxidative stress in major neurodegenerative diseases. In this work, the formation of the Cu(2+) complex with α-syn or with an N-terminal peptide, α-syn(1-19), was confirmed with electrospray-mass spectrometry (ES-MS). The redox potentials of the Cu(2+) complex with α-syn (α-syn-Cu(2+)) and α-syn(1-19) were determined to be 0.018 and 0.053 V, respectively. Furthermore, the Cu(2+) center(s) can be readily reduced to Cu(+), and possible reactions of α-syn-Cu(2+) with cellular species (e.g., O(2), ascorbic acid, and dopamine) were investigated. The occurrence of a redox reaction can be rationalized by comparing the redox potential of the α-syn-Cu(2+) complex to that of the specific cellular species. For example, ascorbic acid can directly reduce α-syn-Cu(2+) to α-syn-Cu(+), setting up a redox cycle in which O(2) is reduced to H(2)O(2) and cellular redox species is continuously exhausted. In addition, the H(2)O(2) generated was demonstrated to reduce viability of the neuroblastoma SY-HY5Y cells. Although our results ruled out the direct oxidation of dopamine by α-syn-Cu(2+), the H(2)O(2) generated in the presence of α-syn-Cu(2+) can oxidize dopamine. Our results suggest that oxidative stress is at least partially responsible for the loss of dopaminergic cells in PD brain and reveal the multifaceted role of the α-syn-Cu(2+) complex in oxidative stress associated with PD symptoms.

  8. Long-Term Stimulant Treatment Affects Brain Dopamine Transporter Level in Patients with Attention Deficit Hyperactive Disorder

    PubMed Central

    Wang, Gene-Jack; Volkow, Nora D.; Wigal, Timothy; Kollins, Scott H.; Newcorn, Jeffrey H.; Telang, Frank; Logan, Jean; Jayne, Millard; Wong, Christopher T.; Han, Hao; Fowler, Joanna S.; Zhu, Wei; Swanson, James M.

    2013-01-01

    Objective Brain dopamine dysfunction in attention deficit/hyperactivity disorder (ADHD) could explain why stimulant medications, which increase dopamine signaling, are therapeutically beneficial. However while the acute increases in dopamine induced by stimulant medications have been associated with symptom improvement in ADHD the chronic effects have not been investigated. Method We used positron emission tomography and [11C]cocaine (dopamine transporter radioligand) to measure dopamine transporter availability in the brains of 18 never-medicated adult ADHD subjects prior to and after 12 months of treatment with methylphenidate and in 11 controls who were also scanned twice at 12 months interval but without stimulant medication. Dopamine transporter availability was quantified as non-displaceable binding potential using a kinetic model for reversible ligands. Results Twelve months of methylphenidate treatment increased striatal dopamine transporter availability in ADHD (caudate, putamen and ventral striatum: +24%, p<0.01); whereas there were no changes in control subjects retested at 12-month interval. Comparisons between controls and ADHD participants revealed no significant difference in dopamine transporter availability prior to treatment but showed higher dopamine transporter availability in ADHD participants than control after long-term treatment (caudate: p<0.007; putamen: p<0.005). Conclusion Upregulation of dopamine transporter availability during long-term treatment with methylphenidate may decrease treatment efficacy and exacerbate symptoms while not under the effects of the medication. Our findings also suggest that the discrepancies in the literature regarding dopamine transporter availability in ADHD participants (some studies reporting increases, other no changes and other decreases) may reflect, in part, differences in treatment histories. PMID:23696790

  9. Long-term stimulant treatment affects brain dopamine transporter level in patients with attention deficit hyperactive disorder.

    PubMed

    Wang, Gene-Jack; Volkow, Nora D; Wigal, Timothy; Kollins, Scott H; Newcorn, Jeffrey H; Telang, Frank; Logan, Jean; Jayne, Millard; Wong, Christopher T; Han, Hao; Fowler, Joanna S; Zhu, Wei; Swanson, James M

    2013-01-01

    Brain dopamine dysfunction in attention deficit/hyperactivity disorder (ADHD) could explain why stimulant medications, which increase dopamine signaling, are therapeutically beneficial. However while the acute increases in dopamine induced by stimulant medications have been associated with symptom improvement in ADHD the chronic effects have not been investigated. We used positron emission tomography and [(11)C]cocaine (dopamine transporter radioligand) to measure dopamine transporter availability in the brains of 18 never-medicated adult ADHD subjects prior to and after 12 months of treatment with methylphenidate and in 11 controls who were also scanned twice at 12 months interval but without stimulant medication. Dopamine transporter availability was quantified as non-displaceable binding potential using a kinetic model for reversible ligands. Twelve months of methylphenidate treatment increased striatal dopamine transporter availability in ADHD (caudate, putamen and ventral striatum: +24%, p<0.01); whereas there were no changes in control subjects retested at 12-month interval. Comparisons between controls and ADHD participants revealed no significant difference in dopamine transporter availability prior to treatment but showed higher dopamine transporter availability in ADHD participants than control after long-term treatment (caudate: p<0.007; putamen: p<0.005). Upregulation of dopamine transporter availability during long-term treatment with methylphenidate may decrease treatment efficacy and exacerbate symptoms while not under the effects of the medication. Our findings also suggest that the discrepancies in the literature regarding dopamine transporter availability in ADHD participants (some studies reporting increases, other no changes and other decreases) may reflect, in part, differences in treatment histories.

  10. Silencing Alpha Synuclein in Mature Nigral Neurons Results in Rapid Neuroinflammation and Subsequent Toxicity

    PubMed Central

    Benskey, Matthew J.; Sellnow, Rhyomi C.; Sandoval, Ivette M.; Sortwell, Caryl E.; Lipton, Jack W.; Manfredsson, Fredric P.

    2018-01-01

    Human studies and preclinical models of Parkinson’s disease implicate the involvement of both the innate and adaptive immune systems in disease progression. Further, pro-inflammatory markers are highly enriched near neurons containing pathological forms of alpha synuclein (α-syn), and α-syn overexpression recapitulates neuroinflammatory changes in models of Parkinson’s disease. These data suggest that α-syn may initiate a pathological inflammatory response, however the mechanism by which α-syn initiates neuroinflammation is poorly understood. Silencing endogenous α-syn results in a similar pattern of nigral degeneration observed following α-syn overexpression. Here we aimed to test the hypothesis that loss of α-syn function within nigrostriatal neurons results in neuronal dysfunction, which subsequently stimulates neuroinflammation. Adeno-associated virus (AAV) expressing an short hairpin RNA (shRNA) targeting endogenous α-syn was unilaterally injected into the substantia nigra pars compacta (SNc) of adult rats, after which nigrostriatal pathology and indices of neuroinflammation were examined at 7, 10, 14 and 21 days post-surgery. Removing endogenous α-syn from nigrostriatal neurons resulted in a rapid up-regulation of the major histocompatibility complex class 1 (MHC-1) within transduced nigral neurons. Nigral MHC-1 expression occurred prior to any overt cell death and coincided with the recruitment of reactive microglia and T-cells to affected neurons. Following the induction of neuroinflammation, α-syn knockdown resulted in a 50% loss of nigrostriatal neurons in the SNc and a corresponding loss of nigrostriatal terminals and dopamine (DA) concentrations within the striatum. Expression of a control shRNA did not elicit any pathological changes. Silencing α-syn within glutamatergic neurons of the cerebellum did not elicit inflammation or cell death, suggesting that toxicity initiated by α-syn silencing is specific to DA neurons. These data provide

  11. Emotional modulation of control dilemmas: the role of positive affect, reward, and dopamine in cognitive stability and flexibility.

    PubMed

    Goschke, Thomas; Bolte, Annette

    2014-09-01

    Goal-directed action in changing environments requires a dynamic balance between complementary control modes, which serve antagonistic adaptive functions (e.g., to shield goals from competing responses and distracting information vs. to flexibly switch between goals and behavioral dispositions in response to significant changes). Too rigid goal shielding promotes stability but incurs a cost in terms of perseveration and reduced flexibility, whereas too weak goal shielding promotes flexibility but incurs a cost in terms of increased distractibility. While research on cognitive control has long been conducted relatively independently from the study of emotion and motivation, it is becoming increasingly clear that positive affect and reward play a central role in modulating cognitive control. In particular, evidence from the past decade suggests that positive affect not only influences the contents of cognitive processes, but also modulates the balance between complementary modes of cognitive control. In this article we review studies from the past decade that examined effects of induced positive affect on the balance between cognitive stability and flexibility with a focus on set switching and working memory maintenance and updating. Moreover, we review recent evidence indicating that task-irrelevant positive affect and performance-contingent rewards exert different and sometimes opposite effects on cognitive control modes, suggesting dissociations between emotional and motivational effects of positive affect. Finally, we critically review evidence for the popular hypothesis that effects of positive affect may be mediated by dopaminergic modulations of neural processing in prefrontal and striatal brain circuits, and we refine this "dopamine hypothesis of positive affect" by specifying distinct mechanisms by which dopamine may mediate effects of positive affect and reward on cognitive control. We conclude with a discussion of limitations of current research, point to

  12. Dopamine and dopamine receptor D1 associated with decreased social interaction.

    PubMed

    Liu, Qiang; Shi, Jieyun; Lin, Rongfei; Wen, Tieqiao

    2017-05-01

    Deficits in social interaction are hallmarks of neurological and psychiatric disorders. However, its underlying mechanism is still unclear. Here, we show that the loss of dendritic cell factor 1 (Dcf1) in the nervous system of mice induces social interaction deficiency, autism-like behaviour, and influences social interaction via the dopamine system. Dopamine receptor D1 agonist rescues this social cognition phenotype, and improves short-term plasticity. Together, this study presents a new genetic mechanism that affects social interaction and may provide a new way to improve positive social interaction and treat autism spectrum disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Early and progressive sensorimotor anomalies in mice overexpressing wild-type human alpha-synuclein.

    PubMed

    Fleming, Sheila M; Salcedo, Jonathan; Fernagut, Pierre-Olivier; Rockenstein, Edward; Masliah, Eliezer; Levine, Michael S; Chesselet, Marie-Françoise

    2004-10-20

    Accumulation of alpha-synuclein in brain is a hallmark of synucleinopathies, neurodegenerative diseases that include Parkinson's disease. Mice overexpressing alpha-synuclein under the Thy-1 promoter (ASO) show abnormal accumulation of alpha-synuclein in cortical and subcortical regions of the brain, including the substantia nigra. We examined the motor deficits in ASO mice with a battery of sensorimotor tests that are sensitive to alterations in the nigrostriatal dopaminergic system. Male wild-type and ASO mice were tested every 2 months for 8 months for motor performance and coordination on a challenging beam, inverted grid, and pole, sensorimotor deficits in an adhesive removal test, spontaneous activity in a cylinder, and gait. Fine motor skills were assessed by the ability to grasp cotton from a bin. ASO mice displayed significant impairments in motor performance and coordination and a reduction in spontaneous activity as early as 2 months of age. Motor performance and coordination impairments became progressively worse with age and sensorimotor deficits appeared at 6 months. Fine motor skills were altered at 4 months and worsened at 8 months. These data indicate that overexpression of alpha-synuclein induced an early and progressive behavioral phenotype that can be detected in multiple tests of sensorimotor function. These behavioral deficits provide a useful way to assess novel drug therapy in genetic models of synucleinopathies.

  14. Pathological α-synuclein in gastrointestinal tissues from prodromal Parkinson disease patients.

    PubMed

    Stokholm, Morten Gersel; Danielsen, Erik Hvid; Hamilton-Dutoit, Stephen Jacques; Borghammer, Per

    2016-06-01

    It has been hypothesized that Lewy pathology initiates in the enteric nervous system years prior to debut of clinical motor symptoms in Parkinson disease patients. This study investigates whether Lewy pathology is present in various gastrointestinal tract tissues from Parkinson disease patients in the prodromal phase. We used the Danish National Pathology Registry to identify archived paraffin-embedded tissue blocks from 57 Parkinson disease patients (98 blocks) and 90 control subjects (98 blocks). We employed 2 different immunohistochemistry techniques visualizing aggregated α-synuclein and phosphorylated α-synuclein. Thirty-nine Parkinson disease patients contributed tissues obtained in the prodromal disease phase, whereas 18 Parkinson disease patients contributed tissues obtained solely after Parkinson diagnosis. Prodromal tissues were obtained on average 7.0 years prior to diagnosis (range = 20 years to 4 months), and postdiagnosis tissue on average 2.8 years after diagnosis (range = 2 days to 18 years). Phosphorylated α-synuclein positivity was seen in 22 of 39 (56%) prodromal Parkinson disease subjects and 30 of 67 (45%) prodromal tissue blocks. These fractions were significantly higher compared to control subjects (p = 0.0001 and p = 0.0032, respectively). In contrast, no significant difference was seen in the positivity rate between prodromal Parkinson disease patients and controls when using the aggregated α-synuclein immunohistochemistry technique. We detected Lewy pathology in the gastrointestinal tract of patients up to 20 years prior to their Parkinson disease diagnosis. These findings are in accordance with a hypothesized prodromal disease phase spanning 10 to 20 years. Ann Neurol 2016;79:940-949. © 2016 American Neurological Association.

  15. THE EFFECT OF GESTATIONAL MERCURY VAPOR EXPOSURE ON RAT BRAIN A-SYNUCLEIN EXPRESSION.

    EPA Science Inventory

    Alpha-synuclein is a highly conserved protein that localizes to pre-synaptic terminals and is thought to play a role in neuronal plasticity. It is upregulated developmentally and continues to be expressed at high levels in the adult brain. Its presence in a number of neuronal (A...

  16. Insulin resistance impairs nigrostriatal dopamine function.

    PubMed

    Morris, J K; Bomhoff, G L; Gorres, B K; Davis, V A; Kim, J; Lee, P-P; Brooks, W M; Gerhardt, G A; Geiger, P C; Stanford, J A

    2011-09-01

    Clinical studies have indicated a link between Parkinson's disease (PD) and Type 2 Diabetes. Although preclinical studies have examined the effect of high-fat feeding on dopamine function in brain reward pathways, the effect of diet on neurotransmission in the nigrostriatal pathway, which is affected in PD and parkinsonism, is less clear. We hypothesized that a high-fat diet, which models early-stage Type 2 Diabetes, would disrupt nigrostriatal dopamine function in young adult Fischer 344 rats. Rats were fed a high fat diet (60% calories from fat) or a normal chow diet for 12 weeks. High fat-fed animals were insulin resistant compared to chow-fed controls. Potassium-evoked dopamine release and dopamine clearance were measured in the striatum using in vivo electrochemistry. Dopamine release was attenuated and dopamine clearance was diminished in the high-fat diet group compared to chow-fed rats. Magnetic resonance imaging indicated increased iron deposition in the substantia nigra of the high fat group. This finding was supported by alterations in the expression of several proteins involved in iron metabolism in the substantia nigra in this group compared to chow-fed animals. The diet-induced systemic and basal ganglia-specific changes may play a role in the observed impairment of nigrostriatal dopamine function. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Formation and implications of alpha-synuclein radical in Maneb- and paraquat-induced models of Parkinson’s disease

    PubMed Central

    Kumar, Ashutosh; Leinisch, Fabian; Kadiiska, Maria B.; Corbett, Jean; Mason, Ronald P.

    2015-01-01

    Parkinson’s disease (PD) is a debilitating, progressive, neurodegenerative disorder characterized by progressive loss of dopaminergic neurons and motor deficits. Alpha-synuclein-containing aggregates represent a feature of a variety of neurodegenerative disorders, including PD; however, the mechanism that initiates and promotes intraneuronal alpha-synuclein aggregation remains unknown. We hypothesized protein radical formation as an initiating mechanism for alpha-synuclein aggregation. Therefore, we used the highly sensitive immuno-spin trapping technique to investigate protein radical formation as a possible mechanism of alpha-synuclein aggregation as well as to investigate the source of protein radical formation in the midbrains of Maneb and paraquat coexposed mice. Coexposure to Maneb and paraquat for 6 weeks resulted in active microgliosis, NADPH oxidase activation, and inducible nitric oxide synthase (iNOS) induction, which culminated in protein radical formation in the midbrains of mice. Results obtained with immuno-spin trapping and immunoprecipitation experiments confirmed formation of alpha-synuclein radicals in dopaminergic neurons of exposed mice. Free radical formation requires NADPH oxidase and iNOS, as indicated by decreased protein radical formation in knockout mice (P47phox−/− and iNOS−/−) and in mice treated with inhibitors such as FeTPPS (a peroxynitrite decomposition catalyst), 1400W (an iNOS inhibitor), or apocynin (a NADPH oxidase inhibitor). Concurrence of protein radical formation with dopaminergic neuronal death indicated a link between protein radicals and disease progression. Taken together, these results show for the first time the formation and detection of the alpha-synuclein radical and suggest that NADPH oxidase and iNOS play roles in peroxynitrite-mediated protein radical formation and subsequent neuronal death in the midbrains of Maneb and paraquat coexposed mice. PMID:25952542

  18. Structural characterization of heparin-induced glyceraldehyde-3-phosphate dehydrogenase protofibrils preventing α-synuclein oligomeric species toxicity.

    PubMed

    Ávila, César L; Torres-Bugeau, Clarisa M; Barbosa, Leandro R S; Sales, Elisa Morandé; Ouidja, Mohand O; Socías, Sergio B; Celej, M Soledad; Raisman-Vozari, Rita; Papy-Garcia, Dulce; Itri, Rosangela; Chehín, Rosana N

    2014-05-16

    Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional enzyme that has been associated with neurodegenerative diseases. GAPDH colocalizes with α-synuclein in amyloid aggregates in post-mortem tissue of patients with sporadic Parkinson disease and promotes the formation of Lewy body-like inclusions in cell culture. In a previous work, we showed that glycosaminoglycan-induced GAPDH prefibrillar species accelerate the conversion of α-synuclein to fibrils. However, it remains to be determined whether the interplay among glycosaminoglycans, GAPDH, and α-synuclein has a role in pathological states. Here, we demonstrate that the toxic effect exerted by α-synuclein oligomers in dopaminergic cell culture is abolished in the presence of GAPDH prefibrillar species. Structural analysis of prefibrillar GAPDH performed by small angle x-ray scattering showed a particle compatible with a protofibril. This protofibril is shaped as a cylinder 22 nm long and a cross-section diameter of 12 nm. Using biocomputational techniques, we obtained the first all-atom model of the GAPDH protofibril, which was validated by cross-linking coupled to mass spectrometry experiments. Because GAPDH can be secreted outside the cell where glycosaminoglycans are present, it seems plausible that GAPDH protofibrils could be assembled in the extracellular space kidnapping α-synuclein toxic oligomers. Thus, the role of GAPDH protofibrils in neuronal proteostasis must be considered. The data reported here could open alternative ways in the development of therapeutic strategies against synucleinopathies like Parkinson disease. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. The contribution of alpha synuclein to neuronal survival and function - Implications for Parkinson's disease.

    PubMed

    Benskey, Matthew J; Perez, Ruth G; Manfredsson, Fredric P

    2016-05-01

    The aggregation of alpha synuclein (α-syn) is a neuropathological feature that defines a spectrum of disorders collectively termed synucleinopathies, and of these, Parkinson's disease (PD) is arguably the best characterized. Aggregated α-syn is the primary component of Lewy bodies, the defining pathological feature of PD, while mutations or multiplications in the α-syn gene result in familial PD. The high correlation between α-syn burden and PD has led to the hypothesis that α-syn aggregation produces toxicity through a gain-of-function mechanism. However, α-syn has been implicated to function in a diverse range of essential cellular processes such as the regulation of neurotransmission and response to cellular stress. As such, an alternative hypothesis with equal explanatory power is that the aggregation of α-syn results in toxicity because of a toxic loss of necessary α-syn function, following sequestration of functional forms α-syn into insoluble protein aggregates. Within this review, we will provide an overview of the literature linking α-syn to PD and the knowledge gained from current α-syn-based animal models of PD. We will then interpret these data from the viewpoint of the α-syn loss-of-function hypothesis and provide a potential mechanistic model by which loss of α-syn function could result in at least some of the neurodegeneration observed in PD. By providing an alternative perspective on the etiopathogenesis of PD and synucleinopathies, this may reveal alternative avenues of research in order to identify potential novel therapeutic targets for disease modifying strategies. The correlation between α-synuclein burden and Parkinson's disease pathology has led to the hypothesis that α-synuclein aggregation produces toxicity through a gain-of-function mechanism. However, in this review, we discuss data supporting the alternative hypothesis that the aggregation of α-synuclein results in toxicity because of loss of necessary α-synuclein

  20. α-Synuclein-induced lysosomal dysfunction occurs through disruptions in protein trafficking in human midbrain synucleinopathy models.

    PubMed

    Mazzulli, Joseph R; Zunke, Friederike; Isacson, Ole; Studer, Lorenz; Krainc, Dimitri

    2016-02-16

    Parkinson's disease (PD) is an age-related neurodegenerative disorder characterized by the accumulation of protein aggregates comprised of α-synuclein (α-syn). A major barrier in treatment discovery for PD is the lack of identifiable therapeutic pathways capable of reducing aggregates in human neuronal model systems. Mutations in key components of protein trafficking and cellular degradation machinery represent important risk factors for PD; however, their precise role in disease progression and interaction with α-syn remains unclear. Here, we find that α-syn accumulation reduced lysosomal degradation capacity in human midbrain dopamine models of synucleinopathies through disrupting hydrolase trafficking. Accumulation of α-syn at the cell body resulted in aberrant association with cis-Golgi-tethering factor GM130 and disrupted the endoplasmic reticulum-Golgi localization of rab1a, a key mediator of vesicular transport. Overexpression of rab1a restored Golgi structure, improved hydrolase trafficking and activity, and reduced pathological α-syn in patient neurons. Our work suggests that enhancement of lysosomal hydrolase trafficking may prove beneficial in synucleinopathies and indicates that human midbrain disease models may be useful for identifying critical therapeutic pathways in PD and related disorders.

  1. Accumulation and distribution of α-synuclein and ubiquitin in the CNS of Gaucher disease mouse models

    PubMed Central

    Xu, YH; Sun, Y; Ran, H; Quinn, B; Witte, D; Grabowski, GA

    2011-01-01

    Gaucher disease, a prevalent lysosomal storage disease, is caused by insufficient activity of acid β-glucosidase (GCase) and resultant glucosylceramide accumulation. Recently in Parkinson disease (PD) patients, heterozygous mutations in GCase have been associated with earlier onset and more progressive PD. To understand the pathogenic relationships between GCase variants and Parkinsonism, α-synuclein and ubiquitin distributions and levels in the brains of several mouse models containing GCase variants were evaluated by immunohistochemistry. Progressive α-synuclein and ubiquitin aggregate accumulations were observed in the cortex, hippocampus, basal ganglia, brainstem, and some cerebellar regions between 4-24 wks in mice that were homozygous for GCase [D409H (9H) or V394L (4L)] variants and also had a prosaposin hypomorphic (PS-NA) transgene. In 4L/PS-NA and 9H/PS-NA mice, this was coincident with progressive neurological manifestations and brain glucosylceramide accumulation. Ultrastructural studies showed electron dense inclusion bodies in neurons and axons of 9H/PS-NA brains. α-Synuclein aggregates were also observed in ventricular, brainstem, and cerebellar regions of older mice (>42-wk) with the GCase variant (D409H/D409H) without overt neurological disease. In a chemically induced GCase deficiency, α-synuclein aggregates and glucosylceramide accumulation also occurred. These studies demonstrate a relationship between glucosylceramide accumulation and α-synuclein aggregates, and implicate glucosylceramide accumulation as risk factor for the α-synucleinopathies. PMID:21257328

  2. Phenylbutyrate Up-regulates the DJ-1 Protein and Protects Neurons in Cell Culture and in Animal Models of Parkinson Disease*

    PubMed Central

    Zhou, Wenbo; Bercury, Kathryn; Cummiskey, Jessica; Luong, Nancy; Lebin, Jacob; Freed, Curt R.

    2011-01-01

    Parkinson disease is caused by the death of midbrain dopamine neurons from oxidative stress, abnormal protein aggregation, and genetic predisposition. In 2003, Bonifati et al. (23) found that a single amino acid mutation in the DJ-1 protein was associated with early-onset, autosomal recessive Parkinson disease (PARK7). The mutation L166P prevents dimerization that is essential for the antioxidant and gene regulatory activity of the DJ-1 protein. Because low levels of DJ-1 cause Parkinson, we reasoned that overexpression might stop the disease. We found that overexpression of DJ-1 improved tolerance to oxidative stress by selectively up-regulating the rate-limiting step in glutathione synthesis. When we imposed a different metabolic insult, A53T mutant α-synuclein, we found that DJ-1 turned on production of the chaperone protein Hsp-70 without affecting glutathione synthesis. After screening a number of small molecules, we have found that the histone deacetylase inhibitor phenylbutyrate increases DJ-1 expression by 300% in the N27 dopamine cell line and rescues cells from oxidative stress and mutant α-synuclein toxicity. In mice, phenylbutyrate treatment leads to a 260% increase in brain DJ-1 levels and protects dopamine neurons against 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP) toxicity. In a transgenic mouse model of diffuse Lewy body disease, long-term administration of phenylbutyrate reduces α-synuclein aggregation in brain and prevents age-related deterioration in motor and cognitive function. We conclude that drugs that up-regulate DJ-1 gene expression may slow the progression of Parkinson disease by moderating oxidative stress and protein aggregation. PMID:21372141

  3. The α‐synuclein gene in multiple system atrophy

    PubMed Central

    Ozawa, T; Healy, D G; Abou‐Sleiman, P M; Ahmadi, K R; Quinn, N; Lees, A J; Shaw, K; Wullner, U; Berciano, J; Moller, J C; Kamm, C; Burk, K; Josephs, K A; Barone, P; Tolosa, E; Goldstein, D B; Wenning, G; Geser, F; Holton, J L; Gasser, T; Revesz, T; Wood, N W

    2006-01-01

    Background The formation of α‐synuclein aggregates may be a critical event in the pathogenesis of multiple system atrophy (MSA). However, the role of this gene in the aetiology of MSA is unknown and untested. Method The linkage disequilibrium (LD) structure of the α‐synuclein gene was established and LD patterns were used to identify a set of tagging single nucleotide polymorphisms (SNPs) that represent 95% of the haplotype diversity across the entire gene. The effect of polymorphisms on the pathological expression of MSA in pathologically confirmed cases was also evaluated. Results and conclusion In 253 Gilman probable or definite MSA patients, 457 possible, probable, and definite MSA cases and 1472 controls, a frequency difference for the individual tagging SNPs or tag‐defined haplotypes was not detected. No effect was observed of polymorphisms on the pathological expression of MSA in pathologically confirmed cases. PMID:16543523

  4. Early events in copper-ion catalyzed oxidation of α-synuclein.

    PubMed

    Tiwari, Manish K; Leinisch, Fabian; Sahin, Cagla; Møller, Ian Max; Otzen, Daniel E; Davies, Michael J; Bjerrum, Morten J

    2018-04-22

    Previous studies on metal-ion catalyzed oxidation of α-synuclein oxidation have mostly used conditions that result in extensive modification precluding an understanding of the early events in this process. In this study, we have examined time-dependent oxidative events related to α-synuclein modification using six different molar ratios of Cu 2+ /H 2 O 2 /protein and Cu 2+ /H 2 O 2 /ascorbate/protein resulting in mild to moderate extents of oxidation. For a Cu 2+ /H 2 O 2 /protein molar ratio of 2.3:7.8:1 only low levels of carbonyls were detected (0.078 carbonyls per protein), whereas a molar ratio of 4.7:15.6:1 gave 0.22 carbonyls per α-synuclein within 15 min. With the latter conditions, rapid conversion of 3 out of 4 methionines (Met) to methionine sulfoxide, and 2 out of 4 tyrosines (Tyr) were converted to products including inter- and intra-molecular dityrosine cross-links and protein oligomers, as determined by SDS-PAGE and Western blot analysis. Limited histidine (His) modification was observed. The rapid formation of dityrosine cross-links was confirmed by fluorescence and mass-spectrometry. These data indicate that Met and Tyr oxidation are early events in Cu 2+ /H 2 O 2 -mediated damage, with carbonyl formation being a minor process. With the Cu 2+ /H 2 O 2 /ascorbate system, rapid protein carbonyl formation was detected with the first 5 min, but after this time point, little additional carbonyl formation was detected. With this system, lower levels of Met and Tyr oxidation were detected (2 Met and 1 Tyr modified with a Cu 2+ /H 2 O 2 /ascorbate/protein ratio of 2.3:7.8:7.8:1), but greater His oxidation. Only low levels of intra- dityrosine cross-links and no inter- dityrosine oligomers were detected under these conditions, suggesting that ascorbate limits Cu 2+ /H 2 O 2 -induced α-synuclein modification. Copyright © 2018. Published by Elsevier Inc.

  5. Modulation of motor behavior by dopamine and the D1-like dopamine receptor AmDOP2 in the honey bee

    PubMed Central

    Mustard, Julie A.; Pham, Priscilla M.; Smith, Brian H.

    2009-01-01

    Determining the specific molecular pathways through which dopamine affects behavior has been complicated by the presence of multiple dopamine receptor subtypes that couple to different second messenger pathways. The observation of freely moving adult bees in an arena was used to investigate the role of dopamine signaling in regulating the behavior of the honey bee. Dopamine or the dopamine receptor antagonist flupenthixol was injected into the hemolymph of worker honey bees. Significant differences between treated and control bees were seen for all behaviors (walking, stopped, upside down, grooming, flying and fanning), and behavioral shifts were dependent on drug dosage and time after injection. To examine the role of dopamine signaling through a specific dopamine receptor in the brain, RNA interference was used to reduce expression levels of a D1-like receptor, AmDOP2. Injection of Amdop2 dsRNA into the mushroom bodies reduced the levels of Amdop2 mRNA and produced significant changes in the amount of time honey bees spent performing specific behaviors with reductions in time spent walking offset by increases in grooming or time spent stopped. Taken together these results establish that dopamine plays an important role in regulating motor behavior of the honey bee. PMID:19945462

  6. Modulation of motor behavior by dopamine and the D1-like dopamine receptor AmDOP2 in the honey bee.

    PubMed

    Mustard, Julie A; Pham, Priscilla M; Smith, Brian H

    2010-04-01

    Determining the specific molecular pathways through which dopamine affects behavior has been complicated by the presence of multiple dopamine receptor subtypes that couple to different second messenger pathways. The observation of freely moving adult bees in an arena was used to investigate the role of dopamine signaling in regulating the behavior of the honey bee. Dopamine or the dopamine receptor antagonist flupenthixol was injected into the hemolymph of worker honey bees. Significant differences between treated and control bees were seen for all behaviors (walking, stopped, upside down, grooming, flying and fanning), and behavioral shifts were dependent on drug dosage and time after injection. To examine the role of dopamine signaling through a specific dopamine receptor in the brain, RNA interference was used to reduce expression levels of a D1-like receptor, AmDOP2. Injection of Amdop2 dsRNA into the mushroom bodies reduced the levels of Amdop2 mRNA and produced significant changes in the amount of time honey bees spent performing specific behaviors with reductions in time spent walking offset by increases in grooming or time spent stopped. Taken together these results establish that dopamine plays an important role in regulating motor behavior of the honey bee. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

  7. Genetic variants of dopamine D2 receptor impact heterodimerization with dopamine D1 receptor.

    PubMed

    Błasiak, Ewa; Łukasiewicz, Sylwia; Szafran-Pilch, Kinga; Dziedzicka-Wasylewska, Marta

    2017-04-01

    The human dopamine D2 receptor gene has three polymorphic variants that alter its amino acid sequence: alanine substitution by valine in position 96 (V96A), proline substitution by serine in position 310 (P310S) and serine substitution by cysteine in position 311 (S311C). Their functional role has never been the object of extensive studies, even though there is some evidence that their occurrence correlates with schizophrenia. The HEK293 cell line was transfected with dopamine D1 and D2 receptors (or genetic variants of the D2 receptor), coupled to fluorescent proteins which allowed us to measure the extent of dimerization of these receptors, using a highly advanced biophysical approach (FLIM-FRET). Additionally, Fluoro-4 AM was used to examine changes in the level of calcium release after ligand stimulation of cells expressing different combinations of dopamine receptors. Using FLIM-FRET experiments we have shown that in HEK 293 expressing dopamine receptors, polymorphic mutations in the D2 receptor play a role in dimmer formation with the dopamine D1 receptor. The association level of dopamine receptors is affected by ligand administration, with variable effects depending on polymorphic variant of the D2 dopamine receptor. We have found that the level of heteromer formation is reflected by calcium ion release after ligand stimulation and have observed variations of this effect dependent on the polymorphic variant and the ligand. The data presented in this paper support the hypothesis on the role of calcium signaling regulated by the D1-D2 heteromer which may be of relevance for schizophrenia etiology. Copyright © 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  8. Flipped Phenyl Ring Orientations of Dopamine Binding with Human and Drosophila Dopamine Transporters: Remarkable Role of Three Nonconserved Residues.

    PubMed

    Yuan, Yaxia; Zhu, Jun; Zhan, Chang-Guo

    2018-03-09

    Molecular modeling and molecular dynamics simulations were performed in the present study to examine the modes of dopamine binding with human and Drosophila dopamine transporters (hDAT and dDAT). The computational data revealed flipped binding orientations of dopamine in hDAT and dDAT due to the major differences in three key residues (S149, G153, and A423 of hDAT vs A117, D121, and S422 of dDAT) in the binding pocket. These three residues dictate the binding orientation of dopamine in the binding pocket, as the aromatic ring of dopamine tends to take an orientation with both the para- and meta-hydroxyl groups being close to polar residues and away from nonpolar residues of the protein. The flipped binding orientations of dopamine in hDAT and dDAT clearly demonstrate a generally valuable insight concerning how the species difference could drastically affect the protein-ligand binding modes, demonstrating that the species difference, which is a factor rarely considered in early drug design stage, must be accounted for throughout the ligand/drug design and discovery processes in general.

  9. Infantile parkinsonism-dystonia: a dopamine "transportopathy".

    PubMed

    Blackstone, Craig

    2009-06-01

    The dopamine transporter (DAT) retrieves the neurotransmitter dopamine from the synaptic cleft at dopaminergic synapses. Variations in solute carrier family 6A, member 3 (SLC6A3/DAT1), the human gene encoding DAT, have been implicated in attention deficit hyperactivity and bipolar disorders, and DAT is a prominent site of action for drugs such as amphetamines and cocaine. In this issue of the JCI, Kurian et al. report that an autosomal recessive infantile parkinsonism-dystonia is caused by loss-of-function mutations in DAT that impair dopamine reuptake (see the related article beginning on page 1595). Though this might be predicted to result in dopamine excess in the synaptic cleft, it likely also causes depletion of presynaptic dopamine stores and possibly downregulation of postsynaptic dopamine receptor function, resulting in impairments in dopaminergic neurotransmission consistent with the clinical presentation. This is the first report of a genetic alteration in DAT function underlying a parkinsonian disorder.

  10. Measurements of auto-antibodies to α-synuclein in the serum and cerebral spinal fluids of patients with Parkinson's disease.

    PubMed

    Akhtar, Rizwan S; Licata, Joseph P; Luk, Kelvin C; Shaw, Leslie M; Trojanowski, John Q; Lee, Virginia M-Y

    2018-03-03

    Biomarkers for α-synuclein are needed for diagnosis and prognosis in Parkinson's disease (PD). Endogenous auto-antibodies to α-synuclein could serve as biomarkers for underlying synucleinopathy, but previous assessments of auto-antibodies have shown variability and inconsistent clinical correlations. We hypothesized that auto-antibodies to α-synuclein could be diagnostic for PD and explain its clinical heterogeneity. To test this hypothesis, we developed an enzyme-linked immunosorbent assay for measuring α-synuclein auto-antibodies in human samples. We evaluated 69 serum samples (16 healthy controls (HC) and 53 PD patients) and 145 CSF samples (52 HC and 93 PD patients) from our Institution. Both serum and CSF were available for 24 participants. Males had higher auto-antibody levels than females in both fluids. CSF auto-antibody levels were significantly higher in PD patients as compared to HC, whereas serum levels were not significantly different. CSF auto-antibody levels did not associate with amyloid-β 1-42 , total tau, or phosphorylated tau. CSF auto-antibody levels correlated with performance on the Montreal Cognitive Assessment, even when controlled for CSF amyloidβ 1-42 . CSF hemoglobin levels, as a proxy for contamination of CSF by blood during lumbar puncture, did not influence these observations. Using recombinant α-synuclein with N- and C-terminal truncations, we found that CSF auto-antibodies target amino acids 100 through 120 of α-synuclein. We conclude that endogenous CSF auto-antibodies are significantly higher in PD patients as compared to HC, suggesting that they could indicate the presence of underlying synucleinopathy. These auto-antibodies associate with poor cognition, independently of CSF amyloidβ 1-42 ., and target a select C-terminal region of α-synuclein. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  11. Tyrosine administration enhances dopamine synthesis and release in light-activated rat retina

    NASA Technical Reports Server (NTRS)

    Gibson, C. J.; Watkins, C. J.; Wurtman, R. J.

    1983-01-01

    Exposure of dark-adapted albino rats to light (350 lux) significantly elevated retinal levels of the dopamine metabolite dihydroxyphenyl acetic acid during the next hour; their return to a dark environment caused dihydroxyphenyl acetic acid levels to fall. Retinal dopamine levels were increased slightly by light exposure, suggesting that the increase in dihydroxyphenyl acetic acid reflected accelerated dopamine synthesis. Administration of tyrosine (100 mg/kg, i.p.) further elevated retinal dihydroxyphenyl acetic acid among light-exposed animals, but failed to affect dopamine release among animals in the dark. These observations show that a physiological stimulus - light exposure - can cause catecholaminergic neurons to become tyrosine-dependent; they also suggest that food consumption may affect neurotransmitter release within the retina.

  12. Amphetamine Paradoxically Augments Exocytotic Dopamine Release and Phasic Dopamine Signals

    PubMed Central

    Daberkow, DP; Brown, HD; Bunner, KD; Kraniotis, SA; Doellman, MA; Ragozzino, ME; Garris, PA; Roitman, MF

    2013-01-01

    Drugs of abuse hijack brain reward circuitry during the addiction process by augmenting action potential-dependent phasic dopamine release events associated with learning and goal-directed behavior. One prominent exception to this notion would appear to be amphetamine (AMPH) and related analogs, which are proposed instead to disrupt normal patterns of dopamine neurotransmission by depleting vesicular stores and promoting non-exocytotic dopamine efflux via reverse transport. This mechanism of AMPH action, though, is inconsistent with its therapeutic effects and addictive properties - which are thought to be reliant on phasic dopamine signaling. Here we used fast-scan cyclic voltammetry in freely moving rats to interrogate principal neurochemical responses to AMPH in the striatum and relate these changes to behavior. First, we showed that AMPH dose-dependently enhanced evoked dopamine responses to phasic-like current pulse trains for up to two hours. Modeling the data revealed that AMPH inhibited dopamine uptake but also unexpectedly potentiated vesicular dopamine release. Second, we found that AMPH increased the amplitude, duration and frequency of spontaneous dopamine transients, the naturally occurring, non-electrically evoked, phasic increases in extracellular dopamine. Finally, using an operant sucrose reward paradigm, we showed that low-dose AMPH augmented dopamine transients elicited by sucrose-predictive cues. However, operant behavior failed at high-dose AMPH, which was due to phasic dopamine hyperactivity and the decoupling of dopamine transients from the reward predictive cue. These findings identify up-regulation of exocytotic dopamine release as a key AMPH action in behaving animals and support a unified mechanism of abused drugs to activate phasic dopamine signaling. PMID:23303926

  13. Direct Correlation Between Ligand-Induced α-Synuclein Oligomers and Amyloid-like Fibril Growth

    PubMed Central

    Nors Perdersen, Martin; Foderà, Vito; Horvath, Istvan; van Maarschalkerweerd, Andreas; Nørgaard Toft, Katrine; Weise, Christoph; Almqvist, Fredrik; Wolf-Watz, Magnus; Wittung-Stafshede, Pernilla; Vestergaard, Bente

    2015-01-01

    Aggregation of proteins into amyloid deposits is the hallmark of several neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. The suggestion that intermediate oligomeric species may be cytotoxic has led to intensified investigations of pre-fibrillar oligomers, which are complicated by their transient nature and low population. Here we investigate alpha-synuclein oligomers, enriched by a 2-pyridone molecule (FN075), and the conversion of oligomers into fibrils. As probed by leakage assays, the FN075 induced oligomers potently disrupt vesicles in vitro, suggesting a potential link to disease related degenerative activity. Fibrils formed in the presence and absence of FN075 are indistinguishable on microscopic and macroscopic levels. Using small angle X-ray scattering, we reveal that FN075 induced oligomers are similar, but not identical, to oligomers previously observed during alpha-synuclein fibrillation. Since the levels of FN075 induced oligomers correlate with the amounts of fibrils among different FN075:protein ratios, the oligomers appear to be on-pathway and modeling supports an ‘oligomer stacking model’ for alpha-synuclein fibril elongation. PMID:26020724

  14. Crosstalk between insulin and dopamine signaling: A basis for the metabolic effects of antipsychotic drugs.

    PubMed

    Nash, Abigail I

    2017-10-01

    In the setting of rising rates of obesity and metabolic syndrome, characterized in part by hyperinsulinemia, it is increasingly important to understand the mechanisms that contribute to insulin dysregulation. The higher risk for metabolic syndrome imparted by antipsychotic medication use highlights one such mechanism. Though there is great variation in the number and types of signaling pathways targeted by these medications, the one common mechanism of action is through dopamine. Dopamine's effects on insulin signaling begin at the level of insulin secretion from the pancreas and continue through the central nervous system. In a reciprocal fashion, insulin also affects dopamine signaling, with specific effects on dopamine reuptake from the synapse. This review probes the dopamine-insulin connection to provide a comprehensive examination of how antipsychotics may contribute towards insulin resistance. Published by Elsevier B.V.

  15. Preventing α-synuclein aggregation: the role of the small heat-shock molecular chaperone proteins.

    PubMed

    Cox, Dezerae; Carver, John A; Ecroyd, Heath

    2014-09-01

    Protein homeostasis, or proteostasis, is the process of maintaining the conformational and functional integrity of the proteome. The failure of proteostasis can result in the accumulation of non-native proteins leading to their aggregation and deposition in cells and in tissues. The amyloid fibrillar aggregation of the protein α-synuclein into Lewy bodies and Lewy neuritis is associated with neurodegenerative diseases classified as α-synucleinopathies, which include Parkinson's disease and dementia with Lewy bodies. The small heat-shock proteins (sHsps) are molecular chaperones that are one of the cell's first lines of defence against protein aggregation. They act to stabilise partially folded protein intermediates, in an ATP-independent manner, to maintain cellular proteostasis under stress conditions. Thus, the sHsps appear ideally suited to protect against α-synuclein aggregation, yet these fail to do so in the context of the α-synucleinopathies. This review discusses how sHsps interact with α-synuclein to prevent its aggregation and, in doing so, highlights the multi-faceted nature of the mechanisms used by sHsps to prevent the fibrillar aggregation of proteins. It also examines what factors may contribute to α-synuclein escaping the sHsp chaperones in the context of the α-synucleinopathies. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  16. Trans-synaptic (GABA-dopamine) modulation of cocaine induced dopamine release: A potential therapeutic strategy for cocaine abuse

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dewey, S.L.; Straughter-Moore, R.; Chen, R.

    We recently developed a new experimental strategy for measuring interactions between functionally-linked neurotransmitter systems in the primate and human brain with PET. As part of this research, we demonstrated that increases in endogenous GABA concentrations significantly reduced striatal dopamine concentrations in the primate brain. We report here the application of the neurotransmitter interaction paradigm with PET and with microdialysis to the investigation of a novel therapeutic strategy for treating cocaine abuse based on the ability of GABA to inhibit cocaine induced increases in striatal dopamine. Using gamma-vinyl GABA (GVG, a suicide inhibitor of GABA transaminase), we performed a series ofmore » PET studies where animals received a baseline PET scan with labeled raclopride injection, animals received cocaine (2.0 mg/kg). Normally, a cocaine challenge significantly reduces the striatal binding of {sup 11}C-raclopride. However, in animals pretreated with GVG, {sup 11}C-raclopride binding was less affected by a cocaine challenge compared to control studies. Furthermore, microdialysis studies in freely moving rats demonstrate that GVG (300 mg/kg) significantly inhibited cocaine-induced increases in extracellular dopamine release. GVG also attenuated cocaine-induced increases in locomotor activity. However, at a dose of 100 mg/kg, GVG had no effect. Similar findings were obtained with alcohol. Alcohol pretreatment dose dependantly (1-4 g/kg) inhibited cocaine-induced increases in extracellular dopamine concentrations in freely moving rats. Taken together, these studies suggest that therapeutic strategies targeted at increasing central GABA concentrations may be beneficial for the treatment of cocaine abuse.« less

  17. Brain dopamine neurone 'damage': methamphetamine users vs. Parkinson's disease - a critical assessment of the evidence.

    PubMed

    Kish, Stephen J; Boileau, Isabelle; Callaghan, Russell C; Tong, Junchao

    2017-01-01

    The objective of this review is to evaluate the evidence that recreational methamphetamine exposure might damage dopamine neurones in human brain, as predicted by experimental animal findings. Brain dopamine marker data in methamphetamine users can now be compared with those in Parkinson's disease, for which the Oleh Hornykiewicz discovery in Vienna of a brain dopamine deficiency is established. Whereas all examined striatal (caudate and putamen) dopamine neuronal markers are decreased in Parkinson's disease, levels of only some (dopamine, dopamine transporter) but not others (dopamine metabolites, synthetic enzymes, vesicular monoamine transporter 2) are below normal in methamphetamine users. This suggests that loss of dopamine neurones might not be characteristic of methamphetamine exposure in at least some human drug users. In methamphetamine users, dopamine loss was more marked in caudate than in putamen, whereas in Parkinson's disease, the putamen is distinctly more affected. Substantia nigra loss of dopamine-containing cell bodies is characteristic of Parkinson's disease, but similar neuropathological studies have yet to be conducted in methamphetamine users. Similarly, it is uncertain whether brain gliosis, a common feature of brain damage, occurs after methamphetamine exposure in humans. Preliminary epidemiological findings suggest that methamphetamine use might increase risk of subsequent development of Parkinson's disease. We conclude that the available literature is insufficient to indicate that recreational methamphetamine exposure likely causes loss of dopamine neurones in humans but does suggest presence of a striatal dopamine deficiency that, in principle, could be corrected by dopamine substitution medication if safety and subject selection considerations can be resolved. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  18. Striatal Neurons Expressing D1 and D2 Receptors are Morphologically Distinct and Differently Affected by Dopamine Denervation in Mice.

    PubMed

    Gagnon, D; Petryszyn, S; Sanchez, M G; Bories, C; Beaulieu, J M; De Koninck, Y; Parent, A; Parent, M

    2017-01-27

    The loss of nigrostriatal dopamine neurons in Parkinson's disease induces a reduction in the number of dendritic spines on medium spiny neurons (MSNs) of the striatum expressing D 1 or D 2 dopamine receptor. Consequences on MSNs expressing both receptors (D 1 /D 2 MSNs) are currently unknown. We looked for changes induced by dopamine denervation in the density, regional distribution and morphological features of D 1 /D 2 MSNs, by comparing 6-OHDA-lesioned double BAC transgenic mice (Drd1a-tdTomato/Drd2-EGFP) to sham-lesioned animals. D 1 /D 2 MSNs are uniformly distributed throughout the dorsal striatum (1.9% of MSNs). In contrast, they are heterogeneously distributed and more numerous in the ventral striatum (14.6% in the shell and 7.3% in the core). Compared to D 1 and D 2 MSNs, D 1 /D 2 MSNs are endowed with a smaller cell body and a less profusely arborized dendritic tree with less dendritic spines. The dendritic spine density of D 1 /D 2 MSNs, but also of D 1 and D 2 MSNs, is significantly reduced in 6-OHDA-lesioned mice. In contrast to D 1 and D 2 MSNs, the extent of dendritic arborization of D 1 /D 2 MSNs appears unaltered in 6-OHDA-lesioned mice. Our data indicate that D 1 /D 2 MSNs in the mouse striatum form a distinct neuronal population that is affected differently by dopamine deafferentation that characterizes Parkinson's disease.

  19. Loss of Mitochondrial Fission Depletes Axonal Mitochondria in Midbrain Dopamine Neurons

    PubMed Central

    Berthet, Amandine; Margolis, Elyssa B.; Zhang, Jue; Hsieh, Ivy; Zhang, Jiasheng; Hnasko, Thomas S.; Ahmad, Jawad; Edwards, Robert H.; Sesaki, Hiromi; Huang, Eric J.

    2014-01-01

    Disruptions in mitochondrial dynamics may contribute to the selective degeneration of dopamine (DA) neurons in Parkinson's disease (PD). However, little is known about the normal functions of mitochondrial dynamics in these neurons, especially in axons where degeneration begins, and this makes it difficult to understand the disease process. To study one aspect of mitochondrial dynamics—mitochondrial fission—in mouse DA neurons, we deleted the central fission protein dynamin-related protein 1 (Drp1). Drp1 loss rapidly eliminates the DA terminals in the caudate–putamen and causes cell bodies in the midbrain to degenerate and lose α-synuclein. Without Drp1, mitochondrial mass dramatically decreases, especially in axons, where the mitochondrial movement becomes uncoordinated. However, in the ventral tegmental area (VTA), a subset of midbrain DA neurons characterized by small hyperpolarization-activated cation currents (Ih) is spared, despite near complete loss of their axonal mitochondria. Drp1 is thus critical for targeting mitochondria to the nerve terminal, and a disruption in mitochondrial fission can contribute to the preferential death of nigrostriatal DA neurons. PMID:25339743

  20. Quantitative measurement of intact alpha-synuclein proteoforms from post-mortem control and Parkinson's disease brain tissue by intact protein mass spectrometry.

    PubMed

    Kellie, John F; Higgs, Richard E; Ryder, John W; Major, Anthony; Beach, Thomas G; Adler, Charles H; Merchant, Kalpana; Knierman, Michael D

    2014-07-23

    A robust top down proteomics method is presented for profiling alpha-synuclein species from autopsied human frontal cortex brain tissue from Parkinson's cases and controls. The method was used to test the hypothesis that pathology associated brain tissue will have a different profile of post-translationally modified alpha-synuclein than the control samples. Validation of the sample processing steps, mass spectrometry based measurements, and data processing steps were performed. The intact protein quantitation method features extraction and integration of m/z data from each charge state of a detected alpha-synuclein species and fitting of the data to a simple linear model which accounts for concentration and charge state variability. The quantitation method was validated with serial dilutions of intact protein standards. Using the method on the human brain samples, several previously unreported modifications in alpha-synuclein were identified. Low levels of phosphorylated alpha synuclein were detected in brain tissue fractions enriched for Lewy body pathology and were marginally significant between PD cases and controls (p = 0.03).

  1. Single-molecule FRET studies on alpha-synuclein oligomerization of Parkinson’s disease genetically related mutants

    NASA Astrophysics Data System (ADS)

    Tosatto, Laura; Horrocks, Mathew H.; Dear, Alexander J.; Knowles, Tuomas P. J.; Dalla Serra, Mauro; Cremades, Nunilo; Dobson, Christopher M.; Klenerman, David

    2015-11-01

    Oligomers of alpha-synuclein are toxic to cells and have been proposed to play a key role in the etiopathogenesis of Parkinson’s disease. As certain missense mutations in the gene encoding for alpha-synuclein induce early-onset forms of the disease, it has been suggested that these variants might have an inherent tendency to produce high concentrations of oligomers during aggregation, although a direct experimental evidence for this is still missing. We used single-molecule Förster Resonance Energy Transfer to visualize directly the protein self-assembly process by wild-type alpha-synuclein and A53T, A30P and E46K mutants and to compare the structural properties of the ensemble of oligomers generated. We found that the kinetics of oligomer formation correlates with the natural tendency of each variant to acquire beta-sheet structure. Moreover, A53T and A30P showed significant differences in the averaged FRET efficiency of one of the two types of oligomers formed compared to the wild-type oligomers, indicating possible structural variety among the ensemble of species generated. Importantly, we found similar concentrations of oligomers during the lag-phase of the aggregation of wild-type and mutated alpha-synuclein, suggesting that the properties of the ensemble of oligomers generated during self-assembly might be more relevant than their absolute concentration for triggering neurodegeneration.

  2. The Role of Dopamine in Inflammation-Associated Depression: Mechanisms and Therapeutic Implications.

    PubMed

    Felger, Jennifer C

    Studies investigating the impact of a variety of inflammatory stimuli on the brain and behavior have consistently reported evidence that inflammatory cytokines affect the basal ganglia and dopamine to mediate depressive symptoms related to motivation and motor activity. Findings have included inflammation-associated reductions in ventral striatal responses to hedonic reward, decreased dopamine and dopamine metabolites in cerebrospinal fluid, and decreased availability of striatal dopamine, all of which correlate with symptoms of anhedonia, fatigue, and psychomotor retardation. Similar relationships between alterations in dopamine-relevant corticostriatal reward circuitry and symptoms of anhedonia and psychomotor slowing have also been observed in patients with major depression who exhibit increased peripheral cytokines and other inflammatory markers, such as C-reactive protein. Of note, these inflammation-associated depressive symptoms are often difficult to treat in patients with medical illnesses or major depression. Furthermore, a wealth of literature suggests that inflammation can decrease dopamine synthesis, packaging, and release, thus sabotaging or circumventing the efficacy of standard antidepressant treatments. Herein, the mechanisms by which inflammation and cytokines affect dopamine neurotransmission are discussed, which may provide novel insights into treatment of inflammation-related behavioral symptoms that contribute to an inflammatory malaise.

  3. Altered machinery of protein synthesis is region- and stage-dependent and is associated with α-synuclein oligomers in Parkinson's disease.

    PubMed

    Garcia-Esparcia, Paula; Hernández-Ortega, Karina; Koneti, Anusha; Gil, Laura; Delgado-Morales, Raul; Castaño, Ester; Carmona, Margarita; Ferrer, Isidre

    2015-12-01

    Parkinson's disease (PD) is characterized by the accumulation of abnormal α-synuclein in selected regions of the brain following a gradient of severity with disease progression. Whether this is accompanied by globally altered protein synthesis is poorly documented. The present study was carried out in PD stages 1-6 of Braak and middle-aged (MA) individuals without alterations in brain in the substantia nigra, frontal cortex area 8, angular gyrus, precuneus and putamen. Reduced mRNA expression of nucleolar proteins nucleolin (NCL), nucleophosmin (NPM1), nucleoplasmin 3 (NPM3) and upstream binding transcription factor (UBF), decreased NPM1 but not NPM3 nucleolar protein immunostaining in remaining neurons; diminished 18S rRNA, 28S rRNA; reduced expression of several mRNAs encoding ribosomal protein (RP) subunits; and altered protein levels of initiation factor eIF3 and elongation factor eEF2 of protein synthesis was found in the substantia nigra in PD along with disease progression. Although many of these changes can be related to neuron loss in the substantia nigra, selective alteration of certain factors indicates variable degree of vulnerability of mRNAs, rRNAs and proteins in degenerating sustantia nigra. NPM1 mRNA and 18S rRNA was increased in the frontal cortex area 8 at stage 5-6; modifications were less marked and region-dependent in the angular gyrus and precuneus. Several RPs were abnormally regulated in the frontal cortex area 8 and precuneus, but only one RP in the angular gyrus, in PD. Altered levels of eIF3 and eIF1, and decrease eEF1A and eEF2 protein levels were observed in the frontal cortex in PD. No modifications were found in the putamen at any time of the study except transient modifications in 28S rRNA and only one RP mRNA at stages 5-6. These observations further indicate marked region-dependent and stage-dependent alterations in the cerebral cortex in PD. Altered solubility and α-synuclein oligomer formation, assessed in total homogenate

  4. Structures of the E46K Mutant-Type α-Synuclein Protein and Impact of E46K Mutation on the Structures of the Wild-Type α-Synuclein Protein

    PubMed Central

    2013-01-01

    The E46K genetic missense mutation of the wild-type α-synuclein protein was recently identified in a family of Spanish origin with hereditary Parkinson’s disease. Detailed understanding of the structures of the monomeric E46K mutant-type α-synuclein protein as well as the impact of the E46K missense mutation on the conformations and free energy landscapes of the wild-type α-synuclein are required for gaining insights into the pathogenic mechanism of Parkinson’s disease. In this study, we use extensive parallel tempering molecular dynamics simulations along with thermodynamic calculations to assess the secondary and tertiary structural properties as well as the conformational preferences of the monomeric wild-type and E46K mutant-type α-synuclein proteins in an aqueous solution environment. We also present the residual secondary structure component conversion stabilities with dynamics using a theoretical strategy, which we most recently developed. To the best of our knowledge, this study presents the first detailed comparison of the structural and thermodynamic properties of the wild-type and E46K mutant-type α-synuclein proteins in an aqueous solution environment at the atomic level with dynamics. We find that the E46K mutation results not only in local but also in long-range changes in the structural properties of the wild-type α-synuclein protein. The mutation site shows a significant decrease in helical content as well as a large increase in β-sheet structure formation upon E46K mutation. In addition, the β-sheet content of the C-terminal region increases significantly in the E46K mutant-type αS in comparison to the wild-type αS. Our theoretical strategy developed to assess the thermodynamic preference of secondary structure transitions indicates that this shift in secondary structure is the result of a decrease in the thermodynamic preference of turn to helix conversions while the coil to β-sheet preference increases for these residues. Long

  5. Parkinson’s Disease

    PubMed Central

    Boyd, James T.; Hamill, Robert W.; Maguire-Zeiss, Kathleen A.

    2015-01-01

    Parkinson’s disease (PD) is the most common age-related motoric neurodegenerative disease initially described in the 1800’s by James Parkinson as the ‘Shaking Palsy’. Loss of the neurotransmitter dopamine was recognized as underlying the pathophysiology of the motor dysfunction; subsequently discovery of dopamine replacement therapies brought substantial symptomatic benefit to PD patients. However, these therapies do not fully treat the clinical syndrome nor do they alter the natural history of this disorder motivating clinicians and researchers to further investigate the clinical phenotype, pathophysiology/pathobiology and etiology of this devastating disease. Although the exact cause of sporadic PD remains enigmatic studies of familial and rare toxicant forms of this disorder have laid the foundation for genome wide explorations and environmental studies. The combination of methodical clinical evaluation, systematic pathological studies and detailed genetic analyses have revealed that PD is a multifaceted disorder with a wide-range of clinical symptoms and pathology that include regions outside the dopamine system. One common thread in PD is the presence of intracytoplasmic inclusions that contain the protein, α-synuclein. The presence of toxic aggregated forms of α-synuclein (e.g., amyloid structures) are purported to be a harbinger of subsequent pathology. In fact, PD is both a cerebral amyloid disease and the most common synucleinopathy, that is, diseases that display accumulations of α-synuclein. Here we present our current understanding of PD etiology, pathology, clinical symptoms and therapeutic approaches with an emphasis on misfolded α-synuclein. PMID:23225012

  6. α-Synuclein binds to the ER-mitochondria tethering protein VAPB to disrupt Ca2+ homeostasis and mitochondrial ATP production.

    PubMed

    Paillusson, Sébastien; Gomez-Suaga, Patricia; Stoica, Radu; Little, Daniel; Gissen, Paul; Devine, Michael J; Noble, Wendy; Hanger, Diane P; Miller, Christopher C J

    2017-07-01

    α-Synuclein is strongly linked to Parkinson's disease but the molecular targets for its toxicity are not fully clear. However, many neuronal functions damaged in Parkinson's disease are regulated by signalling between the endoplasmic reticulum (ER) and mitochondria. This signalling involves close physical associations between the two organelles that are mediated by binding of the integral ER protein vesicle-associated membrane protein-associated protein B (VAPB) to the outer mitochondrial membrane protein, protein tyrosine phosphatase-interacting protein 51 (PTPIP51). VAPB and PTPIP51 thus act as a scaffold to tether the two organelles. Here we show that α-synuclein binds to VAPB and that overexpression of wild-type and familial Parkinson's disease mutant α-synuclein disrupt the VAPB-PTPIP51 tethers to loosen ER-mitochondria associations. This disruption to the VAPB-PTPIP51 tethers is also seen in neurons derived from induced pluripotent stem cells from familial Parkinson's disease patients harbouring pathogenic triplication of the α-synuclein gene. We also show that the α-synuclein induced loosening of ER-mitochondria contacts is accompanied by disruption to Ca 2+ exchange between the two organelles and mitochondrial ATP production. Such disruptions are likely to be particularly damaging to neurons that are heavily dependent on correct Ca 2+ signaling and ATP.

  7. Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates.

    PubMed

    Deeg, Andreas A; Reiner, Anne M; Schmidt, Felix; Schueder, Florian; Ryazanov, Sergey; Ruf, Viktoria C; Giller, Karin; Becker, Stefan; Leonov, Andrei; Griesinger, Christian; Giese, Armin; Zinth, Wolfgang

    2015-09-01

    Special diphenyl-pyrazole compounds and in particular anle138b were found to reduce the progression of prion and Parkinson's disease in animal models. The therapeutic impact of these compounds was attributed to the modulation of α-synuclein and prion-protein aggregation related to these diseases. Photophysical and photochemical properties of the diphenyl-pyrazole compounds anle138b, anle186b and sery313b and their interaction with monomeric and aggregated α-synuclein were studied by fluorescence techniques. The fluorescence emission of diphenyl-pyrazole is strongly increased upon incubation with α-synuclein fibrils, while no change in fluorescence emission is found when brought in contact with monomeric α-synuclein. This points to a distinct interaction between diphenyl-pyrazole and the fibrillar structure with a high binding affinity (Kd=190±120nM) for anle138b. Several α-synuclein proteins form a hydrophobic binding pocket for the diphenyl-pyrazole compound. A UV-induced dehalogenation reaction was observed for anle138b which is modulated by the hydrophobic environment of the fibrils. Fluorescence of the investigated diphenyl-pyrazole compounds strongly increases upon binding to fibrillar α-synuclein structures. Binding at high affinity occurs to hydrophobic pockets in the fibrils. The observed particular fluorescence properties of the diphenyl-pyrazole molecules open new possibilities for the investigation of the mode of action of these compounds in neurodegenerative diseases. The high binding affinity to aggregates and the strong increase in fluorescence upon binding make the compounds promising fluorescence markers for the analysis of aggregation-dependent epitopes. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Striatal Neurons Expressing D1 and D2 Receptors are Morphologically Distinct and Differently Affected by Dopamine Denervation in Mice

    PubMed Central

    Gagnon, D.; Petryszyn, S.; Sanchez, M. G.; Bories, C.; Beaulieu, J. M.; De Koninck, Y.; Parent, A.; Parent, M.

    2017-01-01

    The loss of nigrostriatal dopamine neurons in Parkinson’s disease induces a reduction in the number of dendritic spines on medium spiny neurons (MSNs) of the striatum expressing D1 or D2 dopamine receptor. Consequences on MSNs expressing both receptors (D1/D2 MSNs) are currently unknown. We looked for changes induced by dopamine denervation in the density, regional distribution and morphological features of D1/D2 MSNs, by comparing 6-OHDA-lesioned double BAC transgenic mice (Drd1a-tdTomato/Drd2-EGFP) to sham-lesioned animals. D1/D2 MSNs are uniformly distributed throughout the dorsal striatum (1.9% of MSNs). In contrast, they are heterogeneously distributed and more numerous in the ventral striatum (14.6% in the shell and 7.3% in the core). Compared to D1 and D2 MSNs, D1/D2 MSNs are endowed with a smaller cell body and a less profusely arborized dendritic tree with less dendritic spines. The dendritic spine density of D1/D2 MSNs, but also of D1 and D2 MSNs, is significantly reduced in 6-OHDA-lesioned mice. In contrast to D1 and D2 MSNs, the extent of dendritic arborization of D1/D2 MSNs appears unaltered in 6-OHDA-lesioned mice. Our data indicate that D1/D2 MSNs in the mouse striatum form a distinct neuronal population that is affected differently by dopamine deafferentation that characterizes Parkinson’s disease. PMID:28128287

  9. PSP-CBS with Dopamine Deficiency in a Female with a FMR1 Premutation.

    PubMed

    Paucar, Martin; Beniaminov, Stanislav; Paslawski, Wojciech; Svenningsson, Per

    2016-10-01

    Premutations in the fragile X mental retardation 1 (FMR1) gene cause fragile X-associated tremor/ataxia syndrome (FXTAS) and FMR1-related primary ovarian insufficiency (POI). Female FMR1 premutation carriers rarely develop motor features. Dual pathology is an emerging phenomenon among FMR1 premutation carriers. Here, we describe a family affected by FMR1-related disorders in which the female index case has developed a rapidly progressive and disabling syndrome of atypical parkinsonism. This syndrome consists of early onset postural instability, echolalia, dystonia, and varying types of apraxia like early onset orobuccal apraxia and oculomotor apraxia. She has also developed supranuclear gaze palsy, increased latency of saccade initiation, and slow saccades. These features are compatible with progressive supranuclear palsy (PSP) of a corticobasal syndrome (CBS) variant. Imaging displays a marked reduction of presynaptic dopaminergic uptake and cerebrospinal fluid analysis showed reduced dopamine metabolism; however, the patient is unresponsive to levodopa. Midbrain atrophy ("hummingbird sign") and mild cerebellar atrophy were found on brain MRI. Her father was affected by a typical FXTAS presentation but also displayed dopamine deficiency along with the hummingbird sign. The mechanisms by which FMR1 premutations predispose to atypical parkinsonism and dopamine deficiency await further elucidation.

  10. Dopamine neuron dependent behaviors mediated by glutamate cotransmission

    PubMed Central

    Mingote, Susana; Chuhma, Nao; Kalmbach, Abigail; Thomsen, Gretchen M; Wang, Yvonne; Mihali, Andra; Sferrazza, Caroline; Zucker-Scharff, Ilana; Siena, Anna-Claire; Welch, Martha G; Lizardi-Ortiz, José; Sulzer, David; Moore, Holly; Gaisler-Salomon, Inna; Rayport, Stephen

    2017-01-01

    Dopamine neurons in the ventral tegmental area use glutamate as a cotransmitter. To elucidate the behavioral role of the cotransmission, we targeted the glutamate-recycling enzyme glutaminase (gene Gls1). In mice with a dopamine transporter (Slc6a3)-driven conditional heterozygous (cHET) reduction of Gls1 in their dopamine neurons, dopamine neuron survival and transmission were unaffected, while glutamate cotransmission at phasic firing frequencies was reduced, enabling a selective focus on the cotransmission. The mice showed normal emotional and motor behaviors, and an unaffected response to acute amphetamine. Strikingly, amphetamine sensitization was reduced and latent inhibition potentiated. These behavioral effects, also seen in global GLS1 HETs with a schizophrenia resilience phenotype, were not seen in mice with an Emx1-driven forebrain reduction affecting most brain glutamatergic neurons. Thus, a reduction in dopamine neuron glutamate cotransmission appears to mediate significant components of the GLS1 HET schizophrenia resilience phenotype, and glutamate cotransmission appears to be important in attribution of motivational salience. DOI: http://dx.doi.org/10.7554/eLife.27566.001 PMID:28703706

  11. Dopamine Receptor Activation Increases HIV Entry into Primary Human Macrophages

    PubMed Central

    Gaskill, Peter J.; Yano, Hideaki H.; Kalpana, Ganjam V.; Javitch, Jonathan A.; Berman, Joan W.

    2014-01-01

    Macrophages are the primary cell type infected with HIV in the central nervous system, and infection of these cells is a major component in the development of neuropathogenesis and HIV-associated neurocognitive disorders. Within the brains of drug abusers, macrophages are exposed to increased levels of dopamine, a neurotransmitter that mediates the addictive and reinforcing effects of drugs of abuse such as cocaine and methamphetamine. In this study we examined the effects of dopamine on HIV entry into primary human macrophages. Exposure to dopamine during infection increased the entry of R5 tropic HIV into macrophages, irrespective of the concentration of the viral inoculum. The entry pathway affected was CCR5 dependent, as antagonizing CCR5 with the small molecule inhibitor TAK779 completely blocked entry. The effect was dose-dependent and had a steep threshold, only occurring above 108 M dopamine. The dopamine-mediated increase in entry required dopamine receptor activation, as it was abrogated by the pan-dopamine receptor antagonist flupenthixol, and could be mediated through both subtypes of dopamine receptors. These findings indicate that the effects of dopamine on macrophages may have a significant impact on HIV pathogenesis. They also suggest that drug-induced increases in CNS dopamine may be a common mechanism by which drugs of abuse with distinct modes of action exacerbate neuroinflammation and contribute to HIV-associated neurocognitive disorders in infected drug abusers. PMID:25268786

  12. Pyrethroid pesticide-induced alterations in dopamine transporter function

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Elwan, Mohamed A.; Department of Environmental and Occupational Health, School of Medicine, Emory University, Atlanta, GA 30322; Richardson, Jason R.

    Parkinson's disease (PD) is a progressive neurodegenerative disease affecting the nigrostriatal dopaminergic pathway. Several epidemiological studies have demonstrated an association between pesticide exposure and the incidence of PD. Studies from our laboratory and others have demonstrated that certain pesticides increase levels of the dopamine transporter (DAT), an integral component of dopaminergic neurotransmission and a gateway for dopaminergic neurotoxins. Here, we report that repeated exposure (3 injections over 2 weeks) of mice to two commonly used pyrethroid pesticides, deltamethrin (3 mg/kg) and permethrin (0.8 mg/kg), increases DAT-mediated dopamine uptake by 31 and 28%, respectively. Using cells stably expressing DAT, we determinedmore » that exposure (10 min) to deltamethrin and permethrin (1 nM-100 {mu}M) had no effect on DAT-mediated dopamine uptake. Extending exposures to both pesticides for 30 min (10 {mu}M) or 24 h (1, 5, and 10 {mu}M) resulted in significant decrease in dopamine uptake. This reduction was not the result of competitive inhibition, loss of DAT protein, or cytotoxicity. However, there was an increase in DNA fragmentation, an index of apoptosis, in cells exhibiting reduced uptake at 30 min and 24 h. These data suggest that up-regulation of DAT by in vivo pyrethroid exposure is an indirect effect and that longer-term exposure of cells results in apoptosis. Since DAT can greatly affect the vulnerability of dopamine neurons to neurotoxicants, up-regulation of DAT by deltamethrin and permethrin may increase the susceptibility of dopamine neurons to toxic insult, which may provide insight into the association between pesticide exposure and PD.« less

  13. Regional deficiencies in chaperone-mediated autophagy underlie α-synuclein aggregation and neurodegeneration

    PubMed Central

    Malkus, Kristen A.; Ischiropoulos, Harry

    2012-01-01

    In neurodegenerative diseases, it remains unclear why certain brain regions are selectively vulnerable to protein aggregation. In transgenic mice expressing human A53T α-synuclein, the brainstem and spinal cord develop the most prominent α-synuclein inclusions which correlate with age-dependent motor dysfunction. Herein we present the novel finding that this selective aggregation is in part dependent on the inability of chaperone-mediated autophagy (CMA) to effectively degrade α-synuclein in these brain regions. Lysosomal assays revealed that CMA activity was significantly decreased in aggregation-prone regions compared to the remainder of the brain. Previously, CMA activity has been shown to be proportional to levels of the CMA receptor Lamp-2a. Using antibodies, brain tissue from Lamp-2a null mice, enzymatic deglycosylation, and mass spectrometry, we identified Lamp2a as a novel 72 kDa glycoprotein in the mouse brain. Examination of Lamp-2a levels revealed differences in expression across brain regions. The brainstem and the spinal cord had a more than three-fold greater levels of Lamp-2a as compared to regions less vulnerable to aggregation and exhibited a selective upregulation of Lamp-2a during development of α-synuclein inclusions. Despite this dynamic response of Lamp-2a, the levels of substrates bound to the brain lysosomes as well as the rates of substrate uptake and degradation were not proportional to the levels of Lamp-2a. These regional differences in CMA activity and Lamp-2a expression were found in both non-transgenic mice as well as A53T α-syn mice. Therefore, these are inherent variations and not a transgene-specific effect. However, differences in CMA activity may render select brain regions vulnerable to homeostatic dysfunction in the presence of stressors such as overexpression of human A53T α-syn. Collectively, the data provide a potential mechanism to explain the dichotomy of vulnerability or resistance that underlies brain regions

  14. Infantile parkinsonism-dystonia: a dopamine “transportopathy”

    PubMed Central

    Blackstone, Craig

    2009-01-01

    The dopamine transporter (DAT) retrieves the neurotransmitter dopamine from the synaptic cleft at dopaminergic synapses. Variations in solute carrier family 6A, member 3 (SLC6A3/DAT1), the human gene encoding DAT, have been implicated in attention deficit hyperactivity and bipolar disorders, and DAT is a prominent site of action for drugs such as amphetamines and cocaine. In this issue of the JCI, Kurian et al. report that an autosomal recessive infantile parkinsonism-dystonia is caused by loss-of-function mutations in DAT that impair dopamine reuptake (see the related article beginning on page 1595). Though this might be predicted to result in dopamine excess in the synaptic cleft, it likely also causes depletion of presynaptic dopamine stores and possibly downregulation of postsynaptic dopamine receptor function, resulting in impairments in dopaminergic neurotransmission consistent with the clinical presentation. This is the first report of a genetic alteration in DAT function underlying a parkinsonian disorder. PMID:19504720

  15. Curcumin inhibits aggregation of alpha-synuclein.

    PubMed

    Pandey, Neeraj; Strider, Jeffrey; Nolan, William C; Yan, Sherry X; Galvin, James E

    2008-04-01

    Aggregation of amyloid-beta protein (Abeta) is a key pathogenic event in Alzheimer's disease (AD). Curcumin, a constituent of the Indian spice Turmeric is structurally similar to Congo Red and has been demonstrated to bind Abeta amyloid and prevent further oligomerization of Abeta monomers onto growing amyloid beta-sheets. Reasoning that oligomerization kinetics and mechanism of amyloid formation are similar in Parkinson's disease (PD) and AD, we investigated the effect of curcumin on alpha-synuclein (AS) protein aggregation. In vitro model of AS aggregation was developed by treatment of purified AS protein (wild-type) with 1 mM Fe3+ (Fenton reaction). It was observed that the addition of curcumin inhibited aggregation in a dose-dependent manner and increased AS solubility. The aggregation-inhibiting effect of curcumin was next investigated in cell culture utilizing catecholaminergic SH-SY5Y cell line. A model system was developed in which the red fluorescent protein (DsRed2) was fused with A53T mutant of AS and its aggregation examined under different concentrations of curcumin. To estimate aggregation in an unbiased manner, a protocol was developed in which the images were captured automatically through a high-throughput cell-based screening microscope. The obtained images were processed automatically for aggregates within a defined dimension of 1-6 microm. Greater than 32% decrease in mutant alpha-synuclein aggregation was observed within 48 h subsequent to curcumin addition. Our data suggest that curcumin inhibits AS oligomerization into higher molecular weight aggregates and therefore should be further explored as a potential therapeutic compound for PD and related disorders.

  16. Maternal separation affects dopamine transporter function in the spontaneously hypertensive rat: an in vivo electrochemical study.

    PubMed

    Womersley, Jacqueline S; Hsieh, Jennifer H; Kellaway, Lauriston A; Gerhardt, Greg A; Russell, Vivienne A

    2011-12-01

    Attention-deficit/hyperactivity disorder (ADHD) is a developmental disorder characterised by symptoms of inattention, impulsivity and hyperactivity. The spontaneously hypertensive rat (SHR) is a well-characterised model of this disorder and has been shown to exhibit dopamine dysregulation, one of the hypothesised causes of ADHD. Since stress experienced in the early stages of life can have long-lasting effects on behaviour, it was considered that early life stress may alter development of the dopaminergic system and thereby contribute to the behavioural characteristics of SHR. It was hypothesized that maternal separation would alter dopamine regulation by the transporter (DAT) in ways that distinguish SHR from control rat strains. SHR and control Wistar-Kyoto (WKY) rats were subjected to maternal separation for 3 hours per day from postnatal day 2 to 14. Rats were tested for separation-induced anxiety-like behaviour followed by in vivo chronoamperometry to determine whether changes had occurred in striatal clearance of dopamine by DAT. The rate of disappearance of ejected dopamine was used as a measure of DAT function. Consistent with a model for ADHD, SHR were more active than WKY in the open field. SHR entered the inner zone more frequently and covered a significantly greater distance than WKY. Maternal separation increased the time that WKY spent in the closed arms and latency to enter the open arms of the elevated plus maze, consistent with other rat strains. Of note is that, maternal separation failed to produce anxiety-like behaviour in SHR. Analysis of the chronoamperometric data revealed that there was no difference in DAT function in the striatum of non-separated SHR and WKY. Maternal separation decreased the rate of dopamine clearance (k-1) in SHR striatum. Consistent with this observation, the dopamine clearance time (T100) was increased in SHR. These results suggest that the chronic mild stress of maternal separation impaired the function of striatal

  17. Dopamine agonist withdrawal syndrome: implications for patient care.

    PubMed

    Nirenberg, Melissa J

    2013-08-01

    Dopamine agonists are effective treatments for a variety of indications, including Parkinson's disease and restless legs syndrome, but may have serious side effects, such as orthostatic hypotension, hallucinations, and impulse control disorders (including pathological gambling, compulsive eating, compulsive shopping/buying, and hypersexuality). The most effective way to alleviate these side effects is to taper or discontinue dopamine agonist therapy. A subset of patients who taper a dopamine agonist, however, develop dopamine agonist withdrawal syndrome (DAWS), which has been defined as a severe, stereotyped cluster of physical and psychological symptoms that correlate with dopamine agonist withdrawal in a dose-dependent manner, cause clinically significant distress or social/occupational dysfunction, are refractory to levodopa and other dopaminergic medications, and cannot be accounted for by other clinical factors. The symptoms of DAWS include anxiety, panic attacks, dysphoria, depression, agitation, irritability, suicidal ideation, fatigue, orthostatic hypotension, nausea, vomiting, diaphoresis, generalized pain, and drug cravings. The severity and prognosis of DAWS is highly variable. While some patients have transient symptoms and make a full recovery, others have a protracted withdrawal syndrome lasting for months to years, and therefore may be unwilling or unable to discontinue DA therapy. Impulse control disorders appear to be a major risk factor for DAWS, and are present in virtually all affected patients. Thus, patients who are unable to discontinue dopamine agonist therapy may experience chronic impulse control disorders. At the current time, there are no known effective treatments for DAWS. For this reason, providers are urged to use dopamine agonists judiciously, warn patients about the risks of DAWS prior to the initiation of dopamine agonist therapy, and follow patients closely for withdrawal symptoms during dopamine agonist taper.

  18. Nanomechanical properties of α-synuclein amyloid fibrils: a comparative study by nanoindentation, harmonic force microscopy, and Peakforce QNM

    PubMed Central

    2011-01-01

    We report on the use of three different atomic force spectroscopy modalities to determine the nanomechanical properties of amyloid fibrils of the human α-synuclein protein. α-Synuclein forms fibrillar nanostructures of approximately 10 nm diameter and lengths ranging from 100 nm to several microns, which have been associated with Parkinson's disease. Atomic force microscopy (AFM) has been used to image the morphology of these protein fibrils deposited on a flat surface. For nanomechanical measurements, we used single-point nanoindentation, in which the AFM tip as the indenter is moved vertically to the fibril surface and back while the force is being recorded. We also used two recently developed AFM surface property mapping techniques: Harmonic force microscopy (HarmoniX) and Peakforce QNM. These modalities allow extraction of mechanical parameters of the surface with a lateral resolution and speed comparable to tapping-mode AFM imaging. Based on this phenomenological study, the elastic moduli of the α-synuclein fibrils determined using these three different modalities are within the range 1.3-2.1 GPa. We discuss the relative merits of these three methods for the determination of the elastic properties of protein fibrils, particularly considering the differences and difficulties of each method. PMID:21711775

  19. Prenatal exposure to methanol as a dopamine system sensitization model in C57BL/6J mice

    PubMed Central

    Mackey, Veronica R.; Muthian, Gladson; Smith, Marquitta; King, Jennifer; Charlton, Clivel G.

    2012-01-01

    Aims In this study, the effects of prenatal exposure to methanol (MeOH) on the nigrostriatal dopamine (NSDA) system were examined to determine if the interaction could sensitize this system, and serve as an underpinning for Parkinson's disease (PD) like changes that occur later in life. Methanol was studied because its toxicity resembles the symptoms of PD and the symptoms are relieved by l-dopa meaning that MeOH targets the NSDA system. Since fermentation and wood combustion are major sources for MeOH, the incidence of human encounters with MeOH is high. As a superior solvent and the precursor for formaldehyde, MeOH has a powerful and sometimes, irreversible impact on chemical processes, such as cross-linking proteins and nucleic acids. It may cause subthreshold changes that sensitizes the NSDA system to PD, that occur during aging. Main methods To study the prenatal effects of MeOH, pregnant C57BL/6J mice were administered 40 mg/kg MeOH by oral gavage during gestation days 8–12, twice daily. Twelve weeks after birth, behavior impairments were recorded. The striatum was dissected for the determination of tyrosine hydroxylase (TH), l-aromatic amino acid decarboxylase (LAAD), α-synuclein and levels of dopamine (DA) and its metabolites. Key findings MeOH reduced striatal TH and LAAD protein by 47% and 57% respectively and DA by 32%. Significance The results mean that in utero exposure to toxins similar to MeOH could sensitize the striatal system to changes that cause PD. This study may help identify strategies to block this type of in utero toxicity. PMID:23000099

  20. The role of α-synuclein and tau hyperphosphorylation-mediated autophagy and apoptosis in lead-induced learning and memory injury.

    PubMed

    Zhang, Jianbin; Cai, Tongjian; Zhao, Fang; Yao, Ting; Chen, Yaoming; Liu, Xinqin; Luo, Wenjing; Chen, Jingyuan

    2012-01-01

    Lead (Pb) is a well-known heavy metal in nature. Pb can cause pathophysiological changes in several organ systems including central nervous system. Especially, Pb can affect intelligence development and the ability of learning and memory of children. However, the toxic effects and mechanisms of Pb on learning and memory are still unclear. To clarify the mechanisms of Pb-induced neurotoxicity in hippocampus, and its effect on learning and memory, we chose Sprague-Dawley rats (SD-rats) as experimental subjects. We used Morris water maze to verify the ability of learning and memory after Pb treatment. We used immunohistofluorescence and Western blotting to detect the level of tau phosphorylation, accumulation of α-synuclein, autophagy and related signaling molecules in hippocampus. We demonstrated that Pb can cause abnormally hyperphosphorylation of tau and accumulation of α-synuclein, and these can induce hippocampal injury and the ability of learning and memory damage. To provide the new insight into the underlying mechanisms, we showed that Grp78, ATF4, caspase-3, autophagy-related proteins were induced and highly expressed following Pb-exposure. But mTOR signaling pathway was suppressed in Pb-exposed groups. Our results showed that Pb could cause hyperphosphorylation of tau and accumulation of α-synuclein, which could induce ER stress and suppress mTOR signal pathway. These can enhance type II program death (autophgy) and type I program death (apoptosis) in hippocampus, and impair the ability of learning and memory of rats. This is the first evidence showing the novel role of autophagy in the neurotoxicity of Pb.

  1. Dopamine sensing and measurement using threshold and spectral measurements in random lasers.

    PubMed

    Wan Ismail, Wan Zakiah; Liu, Guozhen; Zhang, Kai; Goldys, Ewa M; Dawes, Judith M

    2016-01-25

    We developed a novel dopamine sensing and measurement technique based on aggregation of gold nanoparticles in random lasers. Dopamine combined with copper ions triggers the aggregation of gold nanoparticles and thus affects the performance of random lasers. Dopamine sensing can be achieved using four parameters which are sensitive to the presence of dopamine, that is emission peak shift, emission linewidth, signal-to-noise ratio (peak emission intensity / noise) and random lasing threshold. The dopamine is most sensitively detected by a change in the emission linewidth with a limit of detection of 1 × 10(-7) M, as well as by an increase in the lasing threshold. The dopamine concentration from 1 × 10(-7) M to 1 × 10(-2) M can be determined by calibrating with the laser threshold.

  2. Dampened Amphetamine-Stimulated Behavior and Altered Dopamine Transporter Function in the Absence of Brain GDNF.

    PubMed

    Kopra, Jaakko J; Panhelainen, Anne; Af Bjerkén, Sara; Porokuokka, Lauriina L; Varendi, Kärt; Olfat, Soophie; Montonen, Heidi; Piepponen, T Petteri; Saarma, Mart; Andressoo, Jaan-Olle

    2017-02-08

    Midbrain dopamine neuron dysfunction contributes to various psychiatric and neurological diseases, including drug addiction and Parkinson's disease. Because of its well established dopaminotrophic effects, the therapeutic potential of glial cell line-derived neurotrophic factor (GDNF) has been studied extensively in various disorders with disturbed dopamine homeostasis. However, the outcomes from preclinical and clinical studies vary, highlighting a need for a better understanding of the physiological role of GDNF on striatal dopaminergic function. Nevertheless, the current lack of appropriate animal models has limited this understanding. Therefore, we have generated novel mouse models to study conditional Gdnf deletion in the CNS during embryonic development and reduction of striatal GDNF levels in adult mice via AAV-Cre delivery. We found that both of these mice have reduced amphetamine-induced locomotor response and striatal dopamine efflux. Embryonic GDNF deletion in the CNS did not affect striatal dopamine levels or dopamine release, but dopamine reuptake was increased due to increased levels of both total and synaptic membrane-associated dopamine transporters. Collectively, these results suggest that endogenous GDNF plays an important role in regulating the function of dopamine transporters in the striatum. SIGNIFICANCE STATEMENT Delivery of ectopic glial cell line-derived neurotrophic factor (GDNF) promotes the function, plasticity, and survival of midbrain dopaminergic neurons, the dysfunction of which contributes to various neurological and psychiatric diseases. However, how the deletion or reduction of GDNF in the CNS affects the function of dopaminergic neurons has remained unknown. Using conditional Gdnf knock-out mice, we found that endogenous GDNF affects striatal dopamine homeostasis and regulates amphetamine-induced behaviors by regulating the level and function of dopamine transporters. These data regarding the physiological role of GDNF are

  3. Consequences of peripheral chemoreflex inhibition with low-dose dopamine in humans

    PubMed Central

    Niewinski, Piotr; Tubek, Stanislaw; Banasiak, Waldemar; Paton, Julian F R; Ponikowski, Piotr

    2014-01-01

    Low-dose dopamine inhibits peripheral chemoreceptors and attenuates the hypoxic ventilatory response (HVR) in humans. However, it is unknown: (1) whether it also modulates the haemodynamic reactions to acute hypoxia, (2) whether it also modulates cardiac baroreflex sensitivity (BRS) and (3) if there is any effect of dopamine withdrawal. We performed a double-blind, placebo-controlled study on 11 healthy male volunteers. At sea level over 2 days every subject was administered low-dose dopamine (2 μg kg–1 min–1) or saline infusion, during which we assessed both ventilatory and haemodynamic responses to acute hypoxia. Separately, we evaluated effects of initiation and withdrawal of each infusion and BRS. The initiation of dopamine infusion did not affect minute ventilation (MV) or mean blood pressure (MAP), but increased both heart rate (HR) and cardiac output. Concomitantly, it decreased systemic vascular resistance. Dopamine blunted the ventilatory, MAP and HR reactions (hypertension, tachycardia) to acute hypoxia. Dopamine attenuated cardiac BRS to falling blood pressure. Dopamine withdrawal evoked an increase in MV. The magnitude of the increment in MV due to dopamine withdrawal correlated with the size of the HVR and depended on the duration of dopamine administration. The ventilatory reaction to dopamine withdrawal constitutes a novel index of peripheral chemoreceptor function. PMID:24396060

  4. α2A- and α2C-Adrenoceptors as Potential Targets for Dopamine and Dopamine Receptor Ligands.

    PubMed

    Sánchez-Soto, Marta; Casadó-Anguera, Verònica; Yano, Hideaki; Bender, Brian Joseph; Cai, Ning-Sheng; Moreno, Estefanía; Canela, Enric I; Cortés, Antoni; Meiler, Jens; Casadó, Vicent; Ferré, Sergi

    2018-03-18

    The poor norepinephrine innervation and high density of Gi/o-coupled α 2A - and α 2C -adrenoceptors in the striatum and the dense striatal dopamine innervation have prompted the possibility that dopamine could be an effective adrenoceptor ligand. Nevertheless, the reported adrenoceptor agonistic properties of dopamine are still inconclusive. In this study, we analyzed the binding of norepinephrine, dopamine, and several compounds reported as selective dopamine D 2 -like receptor ligands, such as the D 3 receptor agonist 7-OH-PIPAT and the D 4 receptor agonist RO-105824, to α 2 -adrenoceptors in cortical and striatal tissue, which express α 2A -adrenoceptors and both α 2A - and α 2C -adrenoceptors, respectively. The affinity of dopamine for α 2 -adrenoceptors was found to be similar to that for D 1 -like and D 2 -like receptors. Moreover, the exogenous dopamine receptor ligands also showed high affinity for α 2A - and α 2C -adrenoceptors. Their ability to activate Gi/o proteins through α 2A - and α 2C -adrenoceptors was also analyzed in transfected cells with bioluminescent resonance energy transfer techniques. The relative ligand potencies and efficacies were dependent on the Gi/o protein subtype. Furthermore, dopamine binding to α 2 -adrenoceptors was functional, inducing changes in dynamic mass redistribution, adenylyl cyclase activity, and ERK1/2 phosphorylation. Binding events were further studied with computer modeling of ligand docking. Docking of dopamine at α 2A - and α 2C -adrenoceptors was nearly identical to its binding to the crystallized D 3 receptor. Therefore, we provide conclusive evidence that α 2A - and α 2C -adrenoceptors are functional receptors for norepinephrine, dopamine, and other previously assumed selective D 2 -like receptor ligands, which calls for revisiting previous studies with those ligands.

  5. Mutations in RAB39B cause X-linked intellectual disability and early-onset Parkinson disease with α-synuclein pathology.

    PubMed

    Wilson, Gabrielle R; Sim, Joe C H; McLean, Catriona; Giannandrea, Maila; Galea, Charles A; Riseley, Jessica R; Stephenson, Sarah E M; Fitzpatrick, Elizabeth; Haas, Stefan A; Pope, Kate; Hogan, Kirk J; Gregg, Ronald G; Bromhead, Catherine J; Wargowski, David S; Lawrence, Christopher H; James, Paul A; Churchyard, Andrew; Gao, Yujing; Phelan, Dean G; Gillies, Greta; Salce, Nicholas; Stanford, Lynn; Marsh, Ashley P L; Mignogna, Maria L; Hayflick, Susan J; Leventer, Richard J; Delatycki, Martin B; Mellick, George D; Kalscheuer, Vera M; D'Adamo, Patrizia; Bahlo, Melanie; Amor, David J; Lockhart, Paul J

    2014-12-04

    Advances in understanding the etiology of Parkinson disease have been driven by the identification of causative mutations in families. Genetic analysis of an Australian family with three males displaying clinical features of early-onset parkinsonism and intellectual disability identified a ∼45 kb deletion resulting in the complete loss of RAB39B. We subsequently identified a missense mutation (c.503C>A [p.Thr168Lys]) in RAB39B in an unrelated Wisconsin kindred affected by a similar clinical phenotype. In silico and in vitro studies demonstrated that the mutation destabilized the protein, consistent with loss of function. In vitro small-hairpin-RNA-mediated knockdown of Rab39b resulted in a reduction in the density of α-synuclein immunoreactive puncta in dendritic processes of cultured neurons. In addition, in multiple cell models, we demonstrated that knockdown of Rab39b was associated with reduced steady-state levels of α-synuclein. Post mortem studies demonstrated that loss of RAB39B resulted in pathologically confirmed Parkinson disease. There was extensive dopaminergic neuron loss in the substantia nigra and widespread classic Lewy body pathology. Additional pathological features included cortical Lewy bodies, brain iron accumulation, tau immunoreactivity, and axonal spheroids. Overall, we have shown that loss-of-function mutations in RAB39B cause intellectual disability and pathologically confirmed early-onset Parkinson disease. The loss of RAB39B results in dysregulation of α-synuclein homeostasis and a spectrum of neuropathological features that implicate RAB39B in the pathogenesis of Parkinson disease and potentially other neurodegenerative disorders. Copyright © 2014 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

  6. Roles of Autophagy in MPP+-Induced Neurotoxicity In Vivo: The Involvement of Mitochondria and α-Synuclein Aggregation

    PubMed Central

    Lin, Ming-Wei; Lei, Yen-Ping; Lin, Anya Maan-yuh

    2014-01-01

    Macroautophagy (also known as autophagy) is an intracellular self-eating mechanism and has been proposed as both neuroprotective and neurodestructive in the central nervous system (CNS) neurodegenerative diseases. In the present study, the role of autophagy involving mitochondria and α-synuclein was investigated in MPP+ (1-methyl-4-phenylpyridinium)-induced oxidative injury in chloral hydrate-anesthetized rats in vivo. The oxidative mechanism underlying MPP+-induced neurotoxicity was identified by elevated lipid peroxidation and heme oxygenase-1 levels, a redox-regulated protein in MPP+-infused substantia nigra (SN). At the same time, MPP+ significantly increased LC3-II levels, a hallmark protein of autophagy. To block MPP+-induced autophagy in rat brain, Atg7siRNA was intranigrally infused 4 d prior to MPP+ infusion. Western blot assay showed that in vivo Atg7siRNA transfection not only reduced Atg7 levels in the MPP+-infused SN but attenuated MPP+-induced elevation in LC3-II levels, activation of caspase 9 and reduction in tyrosine hydroxylase levels, indicating that autophagy is pro-death. The immunostaining study demonstrated co-localization of LC3 and succinate dehydrogenase (a mitochondrial complex II) as well as LC3 and α-synuclein, suggesting that autophagy may engulf mitochondria and α-synuclein. Indeed, in vivo Atg7siRNA transfection mitigated MPP+-induced reduction in cytochrome c oxidase. In addition, MPP+-induced autophagy differentially altered the α-synuclein aggregates in the infused SN. In conclusion, autophagy plays a prodeath role in the MPP+-induced oxidative injury by sequestering mitochondria in the rat brain. Moreover, our data suggest that the benefits of autophagy depend on the levels of α-synuclein aggregates in the nigrostriatal dopaminergic system of the rat brain. PMID:24646838

  7. Loss of mitochondrial fission depletes axonal mitochondria in midbrain dopamine neurons.

    PubMed

    Berthet, Amandine; Margolis, Elyssa B; Zhang, Jue; Hsieh, Ivy; Zhang, Jiasheng; Hnasko, Thomas S; Ahmad, Jawad; Edwards, Robert H; Sesaki, Hiromi; Huang, Eric J; Nakamura, Ken

    2014-10-22

    Disruptions in mitochondrial dynamics may contribute to the selective degeneration of dopamine (DA) neurons in Parkinson's disease (PD). However, little is known about the normal functions of mitochondrial dynamics in these neurons, especially in axons where degeneration begins, and this makes it difficult to understand the disease process. To study one aspect of mitochondrial dynamics-mitochondrial fission-in mouse DA neurons, we deleted the central fission protein dynamin-related protein 1 (Drp1). Drp1 loss rapidly eliminates the DA terminals in the caudate-putamen and causes cell bodies in the midbrain to degenerate and lose α-synuclein. Without Drp1, mitochondrial mass dramatically decreases, especially in axons, where the mitochondrial movement becomes uncoordinated. However, in the ventral tegmental area (VTA), a subset of midbrain DA neurons characterized by small hyperpolarization-activated cation currents (Ih) is spared, despite near complete loss of their axonal mitochondria. Drp1 is thus critical for targeting mitochondria to the nerve terminal, and a disruption in mitochondrial fission can contribute to the preferential death of nigrostriatal DA neurons. Copyright © 2014 the authors 0270-6474/14/3414304-14$15.00/0.

  8. Alpha-synuclein mRNA isoform formation and translation affected by polymorphism in the human SNCA 3'UTR.

    PubMed

    Barrie, Elizabeth S; Lee, Sung-Ha; Frater, John T; Kataki, Maria; Scharre, Douglas W; Sadee, Wolfgang

    2018-05-06

    Multiple variants in SNCA, encoding alpha-synuclein, a main component of Lewy bodies, are implicated in Parkinson's disease. We searched for cis-acting SNCA variants using allelic mRNA ratios in human brain tissues. In a SNCA 3'UTR (2,520 bp) luciferase reporter gene assay, translation in SH-SY5Y cells in the presence of the rs17016074 G/A alleles was measured. To assess clinical impact, we queried neurocognitive genome-wide association studies. Allelic ratios deviated up to twofold, measured at a marker SNP in the middle of a long 3' untranslated region (3'UTR), but not at a marker at its start, suggesting regulation of 3'UTR processing. 3'UTR SNP rs17016074 G/A, minor allele frequency (MAF) <1% in Caucasians, 13% in Africans, strongly associates with large allelic mRNA expression imbalance (AEI), resulting in reduced expression of long 3'UTR isoforms. A second 3'UTR SNP (rs356165) associates with moderate AEI and enhances SNCA mRNA expression. The rs17016074 A allele reduces overall 3'UTR expression in luciferase reporter gene assays but supports more efficient translation, resolving previous contradictory results. We failed to detect significant genome-wide associations for rs17016074, possibly a result of low MAF in Caucasians or its absence from most genotyping panels. In the "Genome Wide Association Study of Yoruba in Nigeria," rs356165 was associated with reduced memory performance. Here, we identify two cis-acting regulatory variants affecting SNCA mRNA expression, measured by allelic ratios in the 3'UTR. The rs17016074 minor A allele is associated with higher expression of luciferase protein activity. Resolving the genetic influence of SNCA polymorphisms requires study of the interactions between multiple regulatory variants with distinct frequencies among populations. © 2018 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.

  9. Parkinson disease affects peripheral sensory nerves in the pharynx.

    PubMed

    Mu, Liancai; Sobotka, Stanislaw; Chen, Jingming; Su, Hungxi; Sanders, Ira; Nyirenda, Themba; Adler, Charles H; Shill, Holly A; Caviness, John N; Samanta, Johan E; Sue, Lucia I; Beach, Thomas G

    2013-07-01

    Dysphagia is very common in patients with Parkinson disease (PD) and often leads to aspiration pneumonia, the most common cause of death in PD. Current therapies are largely ineffective for dysphagia. Because pharyngeal sensation normally triggers the swallowing reflex, we examined pharyngeal sensory nerves in PD patients for Lewy pathology.Sensory nerves supplying the pharynx were excised from autopsied pharynges obtained from patients with clinically diagnosed and neuropathologically confirmed PD (n = 10) and healthy age-matched controls (n = 4). We examined the glossopharyngeal nerve (cranial nerve IX), the pharyngeal sensory branch of the vagus nerve (PSB-X), and the internal superior laryngeal nerve (ISLN) innervating the laryngopharynx. Immunohistochemistry for phosphorylated α-synuclein was used to detect Lewy pathology. Axonal α-synuclein aggregates in the pharyngeal sensory nerves were identified in all of the PD subjects but not in the controls. The density of α-synuclein-positive lesions was greater in PD patients with dysphagia versus those without dysphagia. In addition, α-synuclein-immunoreactive nerve fibers in the ISLN were much more abundant than those in cranial nerve IX and PSB-X. These findings suggest that pharyngeal sensory nerves are directly affected by pathologic processes in PD. These abnormalities may decrease pharyngeal sensation, thereby impairing swallowing and airway protective reflexes and contributing to dysphagia and aspiration.

  10. Diarylheptanoids from Rhizomes of Alpinia officinarum Inhibit Aggregation of α-Synuclein.

    PubMed

    Fu, Guangmiao; Zhang, Wei; Du, Dongsheng; Ng, Yu Pong; Ip, Fanny C F; Tong, Rongbiao; Ip, Nancy Y

    2017-08-09

    Two new diarylheptanoids, alpinin A (1) and alpinin B (2), together with 18 known diarylheptanoids (3-20), were isolated from the rhizomes of Alpinia officinarum. Their structures were elucidated by comprehensive spectroscopic analysis, including high-resolution mass spectrometry, infrared spectroscopy, and one- and two-dimensional nuclear magnetic resonance spectroscopy. Structurally, alpinin A is a new member of the small family of oxa-bridged diarylheptanoids and contains the characteristic 2,6-cis-configured tetrahydropyran motif (C 1 -C 5 oxa bridge). The absolute configuration of alpinin A was confirmed by asymmetric total synthesis of the enantiomer (ent-1), corroborating the assignment of the molecular structure. The absolute configuration of alpinin B was determined on the basis of the analysis of the circular dichroism exciton chirality spectrum. We evaluated the inhibitory activity of all isolated diarylheptanoids against α-synuclein aggregation at 10 μM. Alpinins A and B significantly inhibited α-synuclein aggregation by 66 and 67%, respectively.

  11. Blunted Dopamine Transmission in Addiction: Potential Mechanisms and Implications for Behavior.

    PubMed

    Trifilieff, Pierre; Ducrocq, Fabien; van der Veldt, Suzanne; Martinez, Diana

    2017-01-01

    Positron emission tomography (PET) imaging consistently shows blunted striatal dopamine release and decreased dopamine D2 receptor availability in addiction. Here, we review the preclinical and clinical studies indicating that this neurobiological phenotype is likely to be both a consequence of chronic drug consumption and a vulnerability factor in the development of addiction. We propose that, behaviorally, blunted striatal dopamine transmission could reflect the increased impulsivity and altered cost/benefit computations that are associated with addiction. The factors that influence blunted striatal dopamine transmission in addiction are unknown. Herein, we give an overview of various factors, genetic, environmental, and social, that are known to affect dopamine transmission and that have been associated with the vulnerability to develop addiction. Altogether, these data suggest that blunted dopamine transmission and decreased D2 receptor availability are biomarkers both for the development of addiction and resistance to treatment. These findings support the view that blunted dopamine reflects impulsive behavior and deficits in motivation, which lead to the escalation of drug use. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Interaction between subclinical doses of the Parkinson's disease associated gene, α-synuclein, and the pesticide, rotenone, precipitates motor dysfunction and nigrostriatal neurodegeneration in rats.

    PubMed

    Naughton, Carol; O'Toole, Daniel; Kirik, Deniz; Dowd, Eilís

    2017-01-01

    In most patients, Parkinson's disease is thought to emerge after a lifetime of exposure to, and interaction between, various genetic and environmental risk factors. One of the key genetic factors linked to this condition is α-synuclein, and the α-synuclein protein is pathologically associated with idiopathic cases. However, α-synuclein pathology is also present in presymptomatic, clinically "normal" individuals suggesting that environmental factors, such as Parkinson's disease-linked agricultural pesticides, may be required to precipitate Parkinson's disease in these individuals. In this context, the aim of this study was to assess the behavioural and neuropathological impact of exposing rats with a subclinical load of α-synuclein to subclinical doses of the organic pesticide, rotenone. Rats were randomly assigned to two groups for intra-nigral infusion of AAV 2/5- GFP or AAV 2/5 -α-synuclein. Post viral motor function was assessed at 8, 10 and 12 weeks in the Corridor, Stepping and Whisker tests of lateralised motor function. At week 12, animals were performance-matched to receive a subsequent intra-striatal challenge of the organic pesticide rotenone (or its vehicle) to yield four final groups (Control, Rotenone, AAV 2/5 -α-synuclein and Combined). Behavioural testing resumed one week after rotenone surgery and continued for 5 weeks. We found that, when administered alone, neither intra-nigral AAV-α-synuclein nor intra-striatal rotenone caused sufficient nigrostriatal neurodegeneration to induce a significant motor impairment in their own right. However, when these were administered sequentially to the same rats, the interaction between the two Parkinsonian challenges significantly exacerbated nigrostriatal neurodegeneration which precipitated a pronounced impairment in motor function. These results indicate that exposing rats with a subclinical α-synuclein-induced pathology to the pesticide, rotenone, profoundly exacerbates their Parkinsonian

  13. Dopamine D2-like receptor signaling suppresses human osteoclastogenesis.

    PubMed

    Hanami, Kentaro; Nakano, Kazuhisa; Saito, Kazuyoshi; Okada, Yosuke; Yamaoka, Kunihiro; Kubo, Satoshi; Kondo, Masahiro; Tanaka, Yoshiya

    2013-09-01

    Dopamine, a major neurotransmitter, transmits signals via five different seven-transmembrane G protein-coupled receptors termed D1 to D5. Although the relevance of neuroendocrine system to bone metabolism has been emerging, the precise effects of dopaminergic signaling upon osteoclastogenesis remain unknown. Here, we demonstrate that human monocyte-derived osteoclast precursor cells express all dopamine-receptor subtypes. Dopamine and dopamine D2-like receptor agonists such as pramipexole and quinpirole reduced the formation of TRAP-positive multi-nucleated cells, cathepsin K mRNA expression, and pit formation area in vitro. These inhibitory effects were reversed by pre-treatment with a D2-like receptor antagonist haloperidol or a Gαi inhibitor pertussis toxin, but not with the D1-like receptor antagonist SCH-23390. Dopamine and dopamine D2-like receptor agonists, but not a D1-like receptor agonist, suppressed intracellular cAMP concentration as well as RANKL-meditated induction of c-Fos and NFATc1 mRNA expression in human osteoclast precursor cells. Finally, the dopamine D2-like receptor agonist suppressed LPS-induced osteoclast formation in murine bone marrow culture ex vivo. These findings indicate that dopaminergic signaling plays an important role in bone homeostasis via direct effects upon osteoclast differentiation and further suggest that the clinical use of neuroleptics is likely to affect bone mass. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. RNA interference targeting α-synuclein attenuates methamphetamine-induced neurotoxicity in SH-SY5Y cells.

    PubMed

    Chen, Ling; Huang, Enping; Wang, Huijun; Qiu, Pingming; Liu, Chao

    2013-07-12

    The protein α-synuclein (α-syn) is abundant in neurons and has been claimed to play critical roles in the pathophysiology of Parkinson's disease. Overexpression of α-syn has been shown to be toxicity in methamphetamine (METH)-induced model in vivo and in vitro which has Parkinson's-like pathology. However, the exact mechanisms underlying toxicity of α-syn mediated METH-induced neuron remain unknown. In the present study, human dopaminergic-like neuroblastoma SH-SY5Y cells were used as METH-induced model in vitro. Cell viability was found to be dramatically increased after silencing α-syn expression followed by METH treatment compared with a-syn wild-type cells and the morphological damage to cells after METH treatment was abated through knockdown of α-syn expression in this model. The expression levels of tyrosine hydroxylase (TH), dopamine transporter (DAT) and vesicular monoamine transporter 2(VMAT-2) were significantly decreased and the activity/levels of reactive oxygen species (ROS), nitric oxide synthase (NOS) and nitrogen (NO) were notably increased after METH treatment. However, the changes of these expression levels were reversed in cells transfected with α-syn-shRNA. These results suggested that TH, DAT, VMAT-2, ROS and NOS maybe involved in α-syn mediated METH-induced neuronal toxicity. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Ageing enhances alpha-synuclein, ubiquitin and endoplasmic reticular stress protein expression in the nigral neurons of Asian Indians.

    PubMed

    Alladi, Phalguni Anand; Mahadevan, Anita; Vijayalakshmi, K; Muthane, Uday; Shankar, S K; Raju, T R

    2010-11-01

    Accumulating evidences suggest that dopaminergic neuronal loss in the substantia nigra pars compacta (SNpc) during ageing and in Parkinson's disease (PD) is linked to neurodegenerative changes like exponential increase in alpha-synuclein expression and protein misfolding. Lewy body formation is also a quintessential observation in neurodegeneration and PD. In experimental models of PD, GRP78 a neuroprotective endoplasmic reticulum (ER) chaperone protein targets misfolded proteins for degradation and prevents release of caspase12 from the ER. Release of active caspase12 and its translocation to the nucleus induces ER mediated apoptosis. The effect of ageing on these proteins in human nigra is not known. We evaluated alpha-synuclein, caspase12, GRP78 and ubiquitin expression in the SNpc of Asian Indians, using immunohistochemistry and stereology. The number of alpha-synuclein and caspase12 immunoreactive neurons increased gradually with age whereas the number of GRP78-labeled neurons remained stable. In contrast, GRP78 protein expression was significantly upregulated with age, while alpha-synuclein and caspase12 increased slightly. An increase in the size and numbers of marinesco bodies was prominent after the sixth decade. The mild increase in alpha-synuclein expression and occurrence of marinesco bodies suggests ageing induced protein misfolding and GRP78 upregulation indicates presence of ER stress. The logarithmic upregulation of GRP78 could even be an indicator of neuroprotective or neuromodulatory response of ER to protein misfolding and initiation of unfolded protein response pathway. Since dopaminergic neurons are preserved in ageing Asian Indians, our study possibly signifies better proteasomal or ER response and partially explains the lower prevalence of PD in them. Copyright 2010 Elsevier Ltd. All rights reserved.

  16. Association of α-, β-, and γ-Synuclein With Diffuse Lewy Body Disease

    PubMed Central

    Nishioka, Kenya; Wider, Christian; Vilariño-Güell, Carles; Soto-Ortolaza, Alexandra I.; Lincoln, Sarah J.; Kachergus, Jennifer M.; Jasinska-Myga, Barbara; Ross, Owen A.; Rajput, Alex; Robinson, Christopher A.; Ferman, Tanis J.; Wszolek, Zbigniew K.; Dickson, Dennis W.; Farrer, Matthew J.

    2016-01-01

    Objective To determine the association of the genes that encode α-, β-, and γ-synuclein (SNCA, SNCB, and SNCG, respectively) with diffuse Lewy body disease (DLBD). Design Case-control study. Subjects A total of 172 patients with DLBD consistent with a clinical diagnosis of Parkinson disease dementia/dementia with Lewy bodies and 350 clinically and 97 pathologically normal controls. Interventions Sequencing of SNCA, SNCB, and SNCG and genotyping of single-nucleotide polymorphisms performed on an Applied Biosystems capillary sequencer and a Sequenom MassArray pLEX platform, respectively. Associations were determined using χ2 or Fisher exact tests. Results Initial sequencing studies of the coding regions of each gene in 89 patients with DLBD did not detect any pathogenic substitutions. Nevertheless, genotyping of known polymorphic variability in sequence-conserved regions detected several single-nucleotide polymorphisms in the SNCA and SNCG genes that were significantly associated with disease (P=.05 to <.001). Significant association was also observed for 3 single-nucleotide polymorphisms located in SNCB when comparing DLBD cases and pathologically confirmed normal controls (P=.03-.01); however, this association was not significant for the clinical controls alone or the combined clinical and pathological controls (P>.05). After correction for multiple testing, only 1 single-nucleotide polymorphism in SNCG (rs3750823) remained significant in all of the analyses (P=.05-.009). Conclusion These findings suggest that variants in all 3 members of the synuclein gene family, particularly SNCA and SNCG, affect the risk of developing DLBD and warrant further investigation in larger, pathologically defined data sets as well as clinically diagnosed Parkinson disease/dementia with Lewy bodies case-control series. PMID:20697047

  17. Dopamine agonist 3-PPP fails to protect against MPTP-induced toxicity.

    PubMed

    Muralikrishnan, Dhanasekaran; Ebadi, Manuchair; Brown-Borg, Holly M

    2004-02-01

    We investigated the neuroprotective effect of the dopamine agonist, 3-PPP [3-(3-hydroxyphenyl)-N-propylpiperidine] against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity. MPTP (30 mg/kg, i.p., twice, 16 h apart) causes significant dopamine depletion in nucleus caudatus putamen (NCP) by 1 week. 3-PPP had no effect on the monoamine oxidase-B activity (MAO-B) activity in NCP. 3-PPP did not affect dopamine uptake, whereas mazindol significantly blocked the uptake of dopamine dose dependently. MPTP-induced behavioral changes in mice were not reduced by pretreatment with 3-PPP. This dopamine agonist did not prevent dopamine depletion caused by MPTP. MPP+ (20 microM) significantly inhibited the cell proliferation of SH-SY5Y dopaminergic neuronal cells. 3-PPP had no effect on the SH-SY5Y neuronal cell growth in culture and did not block the MPP(+)-induced cytotoxicity. This study shows that the dopamine agonist 3-PPP failed to protect against MPTP-induced dopaminergic neurotoxicity.

  18. Effect of Dioxygen on Copper(II) Binding to α-Synuclein

    PubMed Central

    Lucas, Heather R.; Lee, Jennifer C.

    2010-01-01

    Using the fluorescent amino acid tryptophan (Trp), we have characterized the copper(II) binding of F4W α-synuclein in the presence and absence of dioxygen at neutral pH. Variations in Trp fluorescence indicate that copper(II) binding is enhanced by the presence of dioxygen, with the apparent dissociation constant (Kd(app)) changing from 100 nM (anaerobic) to 10 nM (aerobic). To investigate the possible role of methionine oxidation, complementary work focused on synthetic peptide models of the N-terminal Cu(II)-α-syn site, MDV(F/W) and M*DV(F/W), where M*= methionine sulfoxide. Furthermore, we employed circular dichroism (CD) spectroscopy to demonstrate that the phenyl-to-indole (F→W) substitution does not alter copper(II) binding properties and to confirm the 1:1 metal-peptide binding stoichiometry. CD comparisons also revealed that Met1 oxidation does not affect the copper-peptide conformation and further suggested the possible existence of a CuII-Trp/Phe (cation-π) interaction. PMID:20064662

  19. The neurosteroid 3 alpha-hydroxy-5 alpha-pregnan-20-one affects dopamine-mediated behavior in rodents.

    PubMed

    Khisti, Rahul T; Deshpande, Laxmikant S; Chopde, Chandrabhan T

    2002-05-01

    The neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP) has been previously shown to induce catalepsy in mice that is modified by GABAergic, dopaminergic, adenosinergic and serotonergic agents. In light of the interaction of this endogenous neurosteroid with GABAergic and dopaminergic transmission, there is potential interest in the possible role of 3alpha,5alpha-THP in psychotic disorders. This study assessed the effect of 3alpha,5alpha-THP in certain dopamine-mediated behavioral paradigms that are widely used to predict antipsychotic-like activity. 3alpha,5alpha-THP (1-8 microg per animal, i.c.v.), the classic neuroleptic (dopamine receptor antagonist) haloperidol (0.25 mg/kg, i.p.), and the benzodiazepine diazepam (7 mg/kg, i.p.) were injected into different groups of animals, and their behavior was screened using the following animal tests: conditioned avoidance response, apomorphine-induced climbing, and amphetamine-induced motor hyperactivity. Separate groups of mice that received 3alpha,5alpha-THP (1-8 microg per animal, i.c.v.) were screened for catalepsy. Furthermore, the effect of a sub-cataleptic dose (0.1 microg per mouse, i.c.v.) of 3alpha,5alpha-THP, either alone or in combination with the GABA(A) receptor antagonist picrotoxin (0.8 mg/kg, i.p.) was measured on haloperidol-induced catalepsy. 3alpha,5alpha-THP like haloperidol reduced conditioned avoidance, apomorphine-induced cage climbing and amphetamine-induced motor hyperactivity. Diazepam only affected conditioned avoidance. 3alpha,5alpha-THP also induced dose-dependent catalepsy. Furthermore, sub-cataleptic doses of 3alpha,5alpha-THP potentiated haloperidol-induced catalepsy. This potentiation was blocked by prior treatment with the GABA(A) receptor antagonist picrotoxin. These findings suggest that 3alpha,5alpha-THP, by its action at the GABA(A) receptors, increases GABAergic tone leading to a behavioral profile similar to that of dopamine receptor antagonists.

  20. Counteracting chemical chaperone effects on the single-molecule α-synuclein structural landscape.

    PubMed

    Ferreon, Allan Chris M; Moosa, Mahdi Muhammad; Gambin, Yann; Deniz, Ashok A

    2012-10-30

    Protein structure and function depend on a close interplay between intrinsic folding energy landscapes and the chemistry of the protein environment. Osmolytes are small-molecule compounds that can act as chemical chaperones by altering the environment in a cellular context. Despite their importance, detailed studies on the role of these chemical chaperones in modulating structure and dimensions of intrinsically disordered proteins have been limited. Here, we used single-molecule Förster resonance energy transfer to test the counteraction hypothesis of counterbalancing effects between the protecting osmolyte trimethylamine-N-oxide (TMAO) and denaturing osmolyte urea for the case of α-synuclein, a Parkinson's disease-linked protein whose monomer exhibits significant disorder. The single-molecule experiments, which avoid complications from protein aggregation, do not exhibit clear solvent-induced cooperative protein transitions for these osmolytes, unlike results from previous studies on globular proteins. Our data demonstrate the ability of TMAO and urea to shift α-synuclein structures towards either more compact or expanded average dimensions. Strikingly, the experiments directly reveal that a 21 [urea][TMAO] ratio has a net neutral effect on the protein's dimensions, a result that holds regardless of the absolute osmolyte concentrations. Our findings shed light on a surprisingly simple aspect of the interplay between urea and TMAO on α-synuclein in the context of intrinsically disordered proteins, with potential implications for the biological roles of such chemical chaperones. The results also highlight the strengths of single-molecule experiments in directly probing the chemical physics of protein structure and disorder in more chemically complex environments.

  1. Counteracting chemical chaperone effects on the single-molecule α-synuclein structural landscape

    PubMed Central

    Ferreon, Allan Chris M.; Moosa, Mahdi Muhammad; Deniz, Ashok A.

    2012-01-01

    Protein structure and function depend on a close interplay between intrinsic folding energy landscapes and the chemistry of the protein environment. Osmolytes are small-molecule compounds that can act as chemical chaperones by altering the environment in a cellular context. Despite their importance, detailed studies on the role of these chemical chaperones in modulating structure and dimensions of intrinsically disordered proteins have been limited. Here, we used single-molecule Förster resonance energy transfer to test the counteraction hypothesis of counterbalancing effects between the protecting osmolyte trimethylamine-N-oxide (TMAO) and denaturing osmolyte urea for the case of α-synuclein, a Parkinson’s disease-linked protein whose monomer exhibits significant disorder. The single-molecule experiments, which avoid complications from protein aggregation, do not exhibit clear solvent-induced cooperative protein transitions for these osmolytes, unlike results from previous studies on globular proteins. Our data demonstrate the ability of TMAO and urea to shift α-synuclein structures towards either more compact or expanded average dimensions. Strikingly, the experiments directly reveal that a 2∶1 [urea]∶[TMAO] ratio has a net neutral effect on the protein’s dimensions, a result that holds regardless of the absolute osmolyte concentrations. Our findings shed light on a surprisingly simple aspect of the interplay between urea and TMAO on α-synuclein in the context of intrinsically disordered proteins, with potential implications for the biological roles of such chemical chaperones. The results also highlight the strengths of single-molecule experiments in directly probing the chemical physics of protein structure and disorder in more chemically complex environments. PMID:22826265

  2. A New Method for Quantitative Immunoblotting of Endogenous α-Synuclein

    PubMed Central

    Newman, Andrew J.; Selkoe, Dennis; Dettmer, Ulf

    2013-01-01

    β-Sheet-rich aggregates of α-synuclein (αSyn) are the hallmark neuropathology of Parkinson’s disease and related synucleinopathies, whereas the principal native structure of αSyn in healthy cells - unfolded monomer or α-helically folded oligomer - is under debate. Our recent crosslinking analysis of αSyn in intact cells showed that a large portion of endogenous αSyn can be trapped as oligomers, most notably as apparent tetramers. One challenge in such studies is accurately quantifying αSyn Western blot signals among samples, as crosslinked αSyn trends toward increased immunoreactivity. Here, we analyzed this phenomenon in detail and found that treatment with the reducible amine-reactive crosslinker DSP strongly increased αSyn immunoreactivity even after cleavage with the reducing agent β-mercaptoethanol. The effect was observed with all αSyn antibodies tested and in all sample types from human brain homogenates to untransfected neuroblastoma cells, permitting easy detection of endogenous αSyn in the latter, which had long been considered impossible. Coomassie staining of blots before and after several hours of washing revealed complete retention of αSyn after DSP/β-mercaptoethanol treatment, in contrast to a marked loss of αSyn without this treatment. The treatment also enhanced immunodetection of the homologs β- and γ-synuclein and of histones, another group of small, lysine-rich proteins. We conclude that by neutralizing positive charges and increasing protein hydrophobicity, amine crosslinker treatment promotes adhesion of αSyn to blotting membranes. These data help explain the recent report of fixing αSyn blots with paraformaldehyde after transfer, which we find produces similar but weaker effects. DSP/β-mercaptoethanol treatment of Western blots should be particularly useful to quantify low-abundance αSyn forms such as extracellular and post-translationally modified αSyn and splice variants. PMID:24278419

  3. Dementia with Lewy bodies in an elderly Greek male due to alpha-synuclein gene mutation.

    PubMed

    Morfis, Litsa; Cordato, Dennis John

    2006-11-01

    We report the case of an elderly man of Greek background who presented with progressive cognitive decline and motor parkinsonism on a background of a strong family history of Parkinson's disease. Associated symptoms included visual hallucinations, excessive daytime drowsiness, recurrent falls, orthostatic hypotension and urinary incontinence. His major clinical symptoms and signs fulfilled consensus criteria for a clinical diagnosis of dementia with Lewy bodies. An alpha-synuclein gene mutation analysis for the G209A substitution was positive. We conclude that the alpha-synuclein (G209A) gene mutation genotype should be considered in the differential diagnosis of dementia with Lewy bodies, particularly in patients with European ancestry and a family history of Parkinson's disease.

  4. A novel autophagy modulator 6-Bio ameliorates SNCA/α-synuclein toxicity

    PubMed Central

    Suresh, S. N.; Chavalmane, Aravinda K.; DJ, Vidyadhara; Yarreiphang, Haorei; Rai, Shashank; Paul, Abhik; Clement, James P.; Alladi, Phalguni Anand; Manjithaya, Ravi

    2017-01-01

    ABSTRACT Parkinson disease (PD) is a life-threatening neurodegenerative movement disorder with unmet therapeutic intervention. We have identified a small molecule autophagy modulator, 6-Bio that shows clearance of toxic SNCA/α-synuclein (a protein implicated in synucleopathies) aggregates in yeast and mammalian cell lines. 6-Bio induces autophagy and dramatically enhances autolysosome formation resulting in SNCA degradation. Importantly, neuroprotective function of 6-Bio as envisaged by immunohistology and behavior analyses in a preclinical model of PD where it induces autophagy in dopaminergic (DAergic) neurons of mice midbrain to clear toxic protein aggregates suggesting that it could be a potential therapeutic candidate for protein conformational disorders. PMID:28350199

  5. Hydroxide ion-mediated synthesis of monodisperse dopamine-melanin nanospheres.

    PubMed

    Cho, Soojeong; Kim, Shin-Hyun

    2015-11-15

    Dopamine-melanin nanospheres are promising materials for photoprotection, structural coloration, and thermoregulation due to their unusual optical and chemical properties. Here, we report the experimental parameters which influence size of dopamine-melanin nanospheres and uniformity. Dopamine precursors are oxidatively polymerized in basic aqueous medium. Therefore, concentration of hydroxide ions significantly influences reaction rate and size of nanospheres. To investigate the effect of hydroxide ions, we adjust three different parameters which affect pH of medium: concentration of sodium hydroxide and dopamine hydrochloride, and reaction temperature. At constant temperature, concentration of hydroxide ions is linearly proportional to initial reaction rates which determine the number of nuclei for nanosphere growth. Temperature alters not only initial reaction rate but also diffusivity of molecules, leading to deviation from the relation between the reaction rate and the number of nuclei. The diameter of dopamine-melanin nanospheres can be readily controlled in a range of 80-490nm through adjusting concentration of dopamine precursor, while maintaining uniform-size distribution and dispersion stability. The synthesized nanospheres are analyzed to confirm the chemical structure, which is composed of approximately 6 indole units. Moreover, surface and chemical properties of the nanospheres are characterized to provide valuable information for surface modification and application. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Parkinson Disease Affects Peripheral Sensory Nerves in the Pharynx

    PubMed Central

    Mu, Liancai; Sobotka, Stanislaw; Chen, Jingming; Su, Hungxi; Sanders, Ira; Nyirenda, Themba; Adler, Charles H.; Shill, Holly A.; Caviness, John N.; Samanta, Johan E.; Sue, Lucia I.; Beach, Thomas G.

    2013-01-01

    Dysphagia is very common in patients with Parkinson’s disease (PD) and often leads to aspiration pneumonia, the most common cause of death in PD. Unfortunately, current therapies are largely ineffective for dysphagia. As pharyngeal sensation normally triggers the swallowing reflex, we examined pharyngeal sensory nerves in PD for Lewy pathology. Sensory nerves supplying the pharynx were excised from autopsied pharynges obtained from patients with clinically diagnosed and neuropathologically confirmed PD (n = 10) and healthy age-matched controls (n = 4). We examined: the glossopharyngeal nerve (IX); the pharyngeal sensory branch of the vagus nerve (PSB-X); and the internal superior laryngeal nerve (ISLN) innervating the laryngopharynx. Immunohistochemistry for phosphorylated α-synuclein was used to detect potential Lewy pathology. Axonal α-synuclein aggregates in the pharyngeal sensory nerves were identified in all of the PD subjects but not in the controls. The density of α-synuclein-positive lesions was significantly greater in PD subjects with documented dysphagia compared to those without dysphagia. In addition, α-synuclein-immunoreactive nerve fibers in the ISLN were much more abundant than those in the IX and PSBX. These findings suggest that pharyngeal sensory nerves are directly affected by the pathologic process of PD. This anatomic pathology may decrease pharyngeal sensation impairing swallowing and airway protective reflexes, thereby contributing to dysphagia and aspiration. PMID:23771215

  7. Parkinson disease: α-synuclein mutational screening and new clinical insight into the p.E46K mutation.

    PubMed

    Pimentel, Márcia M G; Rodrigues, Fabíola C; Leite, Marco Antônio A; Campos Júnior, Mário; Rosso, Ana Lucia; Nicaretta, Denise H; Pereira, João S; Silva, Delson José; Della Coletta, Marcus V; Vasconcellos, Luiz Felipe R; Abreu, Gabriella M; Dos Santos, Jussara M; Santos-Rebouças, Cíntia B

    2015-06-01

    Amongst Parkinson's disease-causing genetic factors, missense mutations and genomic multiplications in the gene encoding α-synuclein are well established causes of the disease, although genetic data in populations with a high degree of admixture, such as the Brazilian one, are still scarce. In this study, we conducted a molecular screening of α-synuclein point mutations and copy number variation in the largest cohort of Brazilian patients with Parkinson's disease (n = 549) and also in twelve Portuguese and one Bolivian immigrants. Genomic DNA was isolated from peripheral blood leukocytes or saliva, and the mutational screening was performed by quantitative and qualitative real-time PCR. The only alteration identified was the p.E46K mutation in a 60-year-old man, born in Bolivia, with a familial history of autosomal dominant Parkinson's disease. This is the second family ever reported, in which this rare pathogenic mutation is segregating. The same mutation was firstly described ten years ago in a Spanish family with a neurodegenerative syndrome combining parkinsonism, dementia and visual hallucinations. The clinical condition of our proband reveals a less aggressive phenotype than previously described and reinforces that marked phenotypic heterogeneity is common among patients with Parkinson's disease, even among those carriers sharing the same mutation. Our findings add new insight into the preexisting information about α-synuclein p.E46K, improving our understanding about the endophenotypes associated to this mutation and corroborate that missense alterations and multiplications in α-synuclein are uncommon among Brazilian patients with Parkinson's disease. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Dopamine dysregulation syndrome: implications for a dopamine hypothesis of bipolar disorder.

    PubMed

    Berk, M; Dodd, S; Kauer-Sant'anna, M; Malhi, G S; Bourin, M; Kapczinski, F; Norman, T

    2007-01-01

    Rational therapeutic development in bipolar is hampered by a lack of pathophysiological model. However, there is a wealth of converging data on the role of dopamine in bipolar disorder. This paper therefore examines the possibility of a dopamine hypothesis for bipolar disorder. A literature search was conducted using standard search engines Embase, PyschLIT, PubMed and MEDLINE. In addition, papers and book chapters known to the authors were retrieved and examined for further relevant articles. Collectively, in excess of 100 articles were reviewed from which approximately 75% were relevant to the focus of this paper. Pharmacological models suggest a role of increased dopaminergic drive in mania and the converse in depression. In Parkinson's disease, administration of high-dose dopamine precursors can produce a 'maniform' picture, which switches into a depressive analogue on withdrawal. It is possible that in bipolar disorder there is a cyclical process, where increased dopaminergic transmission in mania leads to a secondary down regulation of dopaminergic receptor sensitivity over time. This may lead to a period of decreased dopaminergic transmission, corresponding with the depressive phase, and the repetition of the cycle. This model, if verified, may have implications for rational drug development.

  9. Accumulation of phosphorylated alpha-synuclein (p129S) and retinal pathology in a mouse model of Parkinson's disease

    USDA-ARS?s Scientific Manuscript database

    Aims: Parkinson's disease (PD) is a neurodegenerative disorder characterized by accumulation of misfolded alpha-synuclein within the CNS. Although non-motor clinical phenotypes of PD such as visual dysfunction have become increasingly apparent, retinal pathology associated with PD is not well under...

  10. Dopamine, T cells and multiple sclerosis (MS).

    PubMed

    Levite, Mia; Marino, Franca; Cosentino, Marco

    2017-05-01

    Dopamine is a key neurotransmitter that induces critical effects in the nervous system and in many peripheral organs, via 5 dopamine receptors (DRs): D1R-D5R. Dopamine also induces many direct and very potent effects on many DR-expressing immune cells, primarily T cells and dendritic cells. In this review, we focus only on dopamine receptors, effects and production in T cells. Dopamine by itself (at an optimal concentration of~0.1 nM) induces multiple function of resting normal human T cells, among them: T cell adhesion, chemotactic migration, homing, cytokine secretion and others. Interestingly, dopamine activates resting effector T cells (Teffs), but suppresses regulatory T cells (Tregs), and both effects lead eventually to Teff activation. Dopamine-induced effects on T cells are dynamic, context-sensitive and determined by the: T cell activation state, T cell type, DR type, and dopamine concentration. Dopamine itself, and also few dopaminergic molecules/ drugs that are in clinical use for cardiac, neurological and other non-immune indications, have direct effects on human T cells (summarized in this review). These dopaminergic drugs include: dopamine = intropin, L-DOPA, bromocriptine, pramipexole, pergolide, haloperidol, pimozide, and amantadine. Other dopaminergic drugs were not yet tested for their direct effects on T cells. Extensive evidence in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) show dopaminergic dysregulations in T cells in these diseases: D1-like DRs are decreased in Teffs of MS patients, and dopamine does not affect these cells. In contrast, D1-like DRs are increased in Tregs of MS patients, possibly causing functional Treg impairment in MS. Treatment of MS patients with interferon β (IFN-β) increases D1-like DRs and decreases D2-like DRs in Teffs, decreases D1-like DRs in Tregs, and most important: restores responsiveness of patient's Teffs to dopamine. DR agonists and antagonists confer some benefits in

  11. Perinatal methadone exposure affects dopamine, norepinephrine, and serotonin in the weanling rat.

    PubMed

    Robinson, S E; Maher, J R; Wallace, M J; Kunko, P M

    1997-01-01

    On gestational day 7 pregnant rats were implanted with osmotic minipumps containing either methadone hydrochloride (initial dose, 9 mg/kg/day) or sterile water. Their offspring were cross-fostered so that they were exposed to methadone prenatally and/or postnatally. On postnatal day 21, dopamine (DA), norepinephrine (NE), serotonin (5-HT), and their metabolites were analyzed. Perinatal methadone exposure disrupted dopaminergic, noradrenergic, and serotonergic activity in a brain region- and gender-specific fashion. The ratio of the DA metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) to DA was reduced in the frontal cortex of males exposed to methadone postnatally. No effects of perinatal methadone exposure were observed on DA and DOPAC in the striatum. The ratio of 3-methoxy-4-hydroxyphenylglycol (MOPEG) to NE in the hippocampus was increased significantly in males exposed to methadone prenatally. Striatal and parietal cortical 5-hydroxyindoleacetic acid (5-HIAA), but not its ratio to 5-HT, was increased slightly in rats exposed to methadone postnatally. Although parietal cortical 5-HT, 5-HIAA, and 5-hydroxytryptophan were all affected by perinatal methadone exposure, the ratios of metabolite and precursor to 5-HT were not affected. Effects of methadone exposure appeared to depend upon the developmental stage at which exposure occurred and did not appear to result from the phenomenon of neonatal withdrawal. Changes in activity of these three neurotransmitter systems may contribute to the effect of perinatal methadone on the activity of other neurons, such as cholinergic neurons.

  12. Stimulation of Estrogen Receptor Signaling in Breast Cancer by a Novel Chaperone Synuclein Gamma

    DTIC Science & Technology

    2007-06-01

    fertilized eggs (5 ng/ml) of FVB/N mouse. Injected cells were transferred into the oviduct of pseudopregnant ICR female mice and allowed to develop to term...dependent cancers of breast and ovary promoted us to investigate the role of SNCG in regulation of ERα. SNCG strongly stimulated the ligand-dependent...breast tissue. Aberrant expression of SNCG was also associated with ovary cancer progression. Synucleins are a family of small proteins consisting of

  13. The 200-year journey of Parkinson disease: Reflecting on the past and looking towards the future.

    PubMed

    Fahn, Stanley

    2018-01-01

    It took almost 100 years before a meaningful advance occurred in any basic science understanding of Parkinson disease (PD) following James Parkinson's description in 1817. The Lewy body was described in 1912, and the substantia nigra was found to be depigmented with neuronal loss and gliosis in 1919. The link between dopamine and PD began in 1957, 140 years after Parkinson's Essay. Arvid Carlsson and Oleh Hornykiewicz were the major pioneers. The revolutionary therapeutic breakthrough was the introduction of high dosage levodopa therapy by George Cotzias in 1967. Following 40 years of the dopa/dopamine era, we have entered the era of alpha-synuclein, the protein present in Lewy bodies. Heiko Braak found that alpha-synuclein accumulates initially in the olfactory system and lower brainstem and then travels in an anatomic pattern to involve other regions of the brain and thereby cause progressive symptoms. Alpha-synuclein was somehow converted to a rogue protein. Where this originates and how it is propagated are under intense investigation. At the same time that the alpha-synuclein era was developing, clinical advances took place by recognizing PD as hosting a wide variety of nonmotor features with eventual cognitive impairment in many. Therapeutics has also evolved. Although the most effective therapy for the motor features remains levodopa, surgical approaches and drugs for nonmotor problems continue to expand our ability to treat people with PD. We can expect therapeutic advances in neuroprotection as the basic science discoveries uncovered in the alpha-synuclein era are translated into effective treatments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Mutation of Drosophila dopamine receptor DopR leads to male-male courtship behavior.

    PubMed

    Chen, Bin; Liu, He; Ren, Jing; Guo, Aike

    2012-07-06

    In Drosophila, dopamine plays important roles in many biological processes as a neuromodulator. Previous studies showed that dopamine level could affect fly courtship behaviors. Disturbed dopamine level leads to abnormal courtship behavior in two different ways. Dopamine up-regulation induces male-male courtship behavior, while down-regulation of dopamine level results in increased sexual attractiveness of males towards other male flies. Until now, the identity of the dopamine receptor involved in this abnormal male-male courtship behavior remains unknown. Here we used genetic approaches to investigate the role of dopamine receptors in fly courtship behavior. We found that a dopamine D1-like receptor, DopR, was involved in fly courtship behavior. DopR mutant male flies display male-male courtship behavior. This behavior is mainly due to the male's increased propensity to court other males. Expression of functional DopR successfully rescued this mutant phenotype. Knock-down of D2-like receptor D2R and another D1-like receptor, DAMB, did not induce male-male courtship behavior, indicating the receptor-type specificity of this phenomenon. Our findings provide insight into a possible link between dopamine level disturbance and the induced male-male courtship behavior. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Rotigotine is a potent agonist at dopamine D1 receptors as well as at dopamine D2 and D3 receptors.

    PubMed

    Wood, Martyn; Dubois, Vanessa; Scheller, Dieter; Gillard, Michel

    2015-02-01

    Rotigotine acts as a dopamine receptor agonist with high affinity for the dopamine D2, D3, D4 and D5 receptors but with a low affinity for the dopamine D1 receptor. We have investigated this further in radioligand binding and functional studies and compared the profile of rotigotine with that of other drugs used in the treatment of Parkinson's disease (PD). The binding of rotigotine to human dopamine D1, D2, D3, D4 and D5 receptors was determined in radioligand binding studies using [(3)H]rotigotine and compared with that of standard antagonist radioligands. Functional interactions of rotigotine with human dopamine receptors was also determined. [(3)H]rotigotine can be used as an agonist radioligand to label all dopamine receptor subtypes and this can be important to derive agonist affinity estimates. Rotigotine maintains this high affinity in functional studies at all dopamine receptors especially D1, D2 and D3 receptors and, to a lesser extent, D4 and D5 receptors. Rotigotine, like apomorphine but unlike ropinirole and pramipexole, was a potent agonist at all dopamine receptors. Rotigotine is a high-potency agonist at human dopamine D1, D2 and D3 receptors with a lower potency at D4 and D5 receptors. These studies differentiate rotigotine from conventional dopamine D2 agonists, used in the treatment of PD, such as ropinirole and pramipexole which lack activity at the D1 and D5 receptors, but resembles that of apomorphine which has greater efficacy in PD than other dopamine agonists but has suboptimal pharmacokinetic properties. © 2014 The British Pharmacological Society.

  16. Rotigotine is a potent agonist at dopamine D1 receptors as well as at dopamine D2 and D3 receptors

    PubMed Central

    Wood, Martyn; Dubois, Vanessa; Scheller, Dieter; Gillard, Michel

    2015-01-01

    Background and Purpose Rotigotine acts as a dopamine receptor agonist with high affinity for the dopamine D2, D3, D4 and D5 receptors but with a low affinity for the dopamine D1 receptor. We have investigated this further in radioligand binding and functional studies and compared the profile of rotigotine with that of other drugs used in the treatment of Parkinson's disease (PD). Experimental Approach The binding of rotigotine to human dopamine D1, D2, D3, D4 and D5 receptors was determined in radioligand binding studies using [3H]rotigotine and compared with that of standard antagonist radioligands. Functional interactions of rotigotine with human dopamine receptors was also determined. Key Results [3H]rotigotine can be used as an agonist radioligand to label all dopamine receptor subtypes and this can be important to derive agonist affinity estimates. Rotigotine maintains this high affinity in functional studies at all dopamine receptors especially D1, D2 and D3 receptors and, to a lesser extent, D4 and D5 receptors. Rotigotine, like apomorphine but unlike ropinirole and pramipexole, was a potent agonist at all dopamine receptors. Conclusions and Implications Rotigotine is a high-potency agonist at human dopamine D1, D2 and D3 receptors with a lower potency at D4 and D5 receptors. These studies differentiate rotigotine from conventional dopamine D2 agonists, used in the treatment of PD, such as ropinirole and pramipexole which lack activity at the D1 and D5 receptors, but resembles that of apomorphine which has greater efficacy in PD than other dopamine agonists but has suboptimal pharmacokinetic properties. PMID:25339241

  17. Further exploration of the conformational space of α-synuclein fibrils: solid-state NMR assignment of a high-pH polymorph.

    PubMed

    Verasdonck, Joeri; Bousset, Luc; Gath, Julia; Melki, Ronald; Böckmann, Anja; Meier, Beat H

    2016-04-01

    Polymorphism is a common and important phenomenon for protein fibrils which has been linked to the appearance of strains in prion and other neurodegenerative diseases. Parkinson disease is a frequently occurring neurodegenerative pathology, tightly associated with the formation of Lewy bodies. These deposits mainly consist of α-synuclein in fibrillar, β-sheet-rich form. α-synuclein is known to form numerous different polymorphs, which show distinct structural features. Here, we describe the chemical shift assignments, and derive the secondary structure, of a polymorph that was fibrillized at higher-than-physiological pH conditions. The fibrillar core contains residues 40-95, with both the C- and N-terminus not showing any ordered, rigid parts. The chemical shifts are similar to those recorded previously for an assigned polymorph that was fibrillized at neutral pH.

  18. Reduction of dopamine level enhances the attractiveness of male Drosophila to other males.

    PubMed

    Liu, Tong; Dartevelle, Laurence; Yuan, Chunyan; Wei, Hongping; Wang, Ying; Ferveur, Jean-François; Guo, Aike

    2009-01-01

    Dopamine is an important neuromodulator in animals and its roles in mammalian sexual behavior are extensively studied. Drosophila as a useful model system is widely used in many fields of biological studies. It has been reported that dopamine reduction can affect female receptivity in Drosophila and leave male-female courtship behavior unaffected. Here, we used genetic and pharmacological approaches to decrease the dopamine level in dopaminergic cells in Drosophila, and investigated the consequence of this manipulation on male homosexual courtship behavior. We find that reduction of dopamine level can induce Drosophila male-male courtship behavior, and that this behavior is mainly due to the increased male attractiveness or decreased aversiveness towards other males, but not to their enhanced propensity to court other males. Chemical signal input probably plays a crucial role in the male-male courtship induced by the courtees with reduction of dopamine. Our finding provides insight into the relationship between the dopamine reduction and male-male courtship behavior, and hints dopamine level is important for controlling Drosophila courtship behavior.

  19. Reduction of Dopamine Level Enhances the Attractiveness of Male Drosophila to Other Males

    PubMed Central

    Liu, Tong; Dartevelle, Laurence; Yuan, Chunyan; Wei, Hongping; Wang, Ying; Ferveur, Jean-François; Guo, Aike

    2009-01-01

    Dopamine is an important neuromodulator in animals and its roles in mammalian sexual behavior are extensively studied. Drosophila as a useful model system is widely used in many fields of biological studies. It has been reported that dopamine reduction can affect female receptivity in Drosophila and leave male-female courtship behavior unaffected. Here, we used genetic and pharmacological approaches to decrease the dopamine level in dopaminergic cells in Drosophila, and investigated the consequence of this manipulation on male homosexual courtship behavior. We find that reduction of dopamine level can induce Drosophila male-male courtship behavior, and that this behavior is mainly due to the increased male attractiveness or decreased aversiveness towards other males, but not to their enhanced propensity to court other males. Chemical signal input probably plays a crucial role in the male-male courtship induced by the courtees with reduction of dopamine. Our finding provides insight into the relationship between the dopamine reduction and male-male courtship behavior, and hints dopamine level is important for controlling Drosophila courtship behavior. PMID:19238209

  20. Current and experimental treatments of Parkinson disease: A guide for neuroscientists.

    PubMed

    Oertel, Wolfgang; Schulz, Jörg B

    2016-10-01

    Over a period of more than 50 years, the symptomatic treatment of the motor symptoms of Parkinson disease (PD) has been optimized using pharmacotherapy, deep brain stimulation, and physiotherapy. The arsenal of pharmacotherapies includes L-Dopa, several dopamine agonists, inhibitors of monoamine oxidase (MAO)-B and catechol-o-methyltransferase (COMT), and amantadine. In the later course of the disease, motor complications occur, at which stage different oral formulations of L-Dopa or dopamine agonists with long half-life, a transdermal application or parenteral pumps for continuous drug supply can be subscribed. Alternatively, the patient is offered deep brain stimulation of the subthalamic nucleus (STN) or the internal part of the globus pallidus (GPi). For a more efficacious treatment of motor complications, new formulations of L-Dopa, dopamine agonists, and amantadine as well as new MAO-B and COMT inhibitors are currently tested in clinical trials, and some of them already yielding positive results in phase 3 trials. In addition, non-dopaminergic agents have been tested in the early clinical phase for the treatment of motor fluctuations and dyskinesia, including adenosine A2A antagonists (istradefylline, preladenant, and tozadenant) and modulators of the metabolic glutamate receptor 5 (mGluR5 - mavoglurant) and serotonin (eltoprazine) receptors. Recent clinical trials testing coenzyme Q10, the dopamine agonist pramipexole, creatine monohydrate, pioglitazone, or AAV-mediated gene therapy aimed at increasing expression of neurturin, did not prove efficacious. Treatment with nicotine, caffeine, inosine (a precursor of urate), and isradipine (a dihydropyridine calcium channel blocker), as well as active and passive immunization against α-synuclein and inhibitors or modulators of α-synuclein-aggregation are currently studied in clinical trials. However, to date, no disease-modifying treatment is available. We here review the current status of treatment options for

  1. The association of metal ion exposure with alpha-synuclein-like immunoreactivity in the central nervous system of fish, Catostomus commersoni.

    PubMed

    Boudreau, Heather S; Krol, Karmen M; Eibl, Joseph K; Williams, Linda D; Rossiter, John P; Palace, Vincent P; Ross, Gregory M

    2009-05-17

    Alpha-synuclein protein aggregates are a major component of Lewy bodies, the intracytoplasmic inclusions found in dopaminergic neurons that are a defining characteristic of Parkinson's disease. Other "synucleopathies" include dementia with Lewy bodies and multisystem atrophy. In vitro, the formation of these deposits can be induced by a number of substances, including metal ions. Fish provide a useful model to study the long-term biological effects of metal ion exposure, but to date no studies have been reported concerning such exposures with respect to alpha-synuclein aggregation. Mature white sucker fish (Catostomus commersoni; aged 5-8 years) were sampled from two sites within the Red Lake area of Northwestern Ontario, a region highly contaminated by metal ions due to mining activity. Individual fish were characterized with respect to liver metal ion uptake and metallothionein levels. Central nervous system (CNS) tissues of fish from test sites representing high and low metal ion contamination were examined immunohistochemically using a polyclonal antibody recognising alpha-synuclein protein. We demonstrate here that the CNS of fish exposed to elevated metal ion environments had increased alpha-synuclein-like immunoreactive aggregates, potentially reflecting metal ion exposure leading to CNS toxicity. These findings demonstrate that fish may be an important new model for studying environmental risk factors and the pathology associated with Parkinson's disease.

  2. Long-Term Citalopram Treatment Alters the Stress Responses of the Cortical Dopamine and Noradrenaline Systems: the Role of Cortical 5-HT1A Receptors

    PubMed Central

    Kaneko, Fumi; Kishikawa, Yuki; Hanada, Yuuki; Yamada, Makiko; Kakuma, Tatsuyuki; Kawahara, Hiroshi; Nishi, Akinori

    2016-01-01

    Background: Cortical dopamine and noradrenaline are involved in the stress response. Citalopram, a selective serotonin reuptake inhibitor, has direct and indirect effects on the serotonergic system. Furthermore, long-term treatment with citalopram affects the dopamine and noradrenaline systems, which could contribute to the therapeutic action of antidepressants. Methods: The effects of long-term treatment with citalopram on the responses of the dopamine and noradrenaline systems in the rat prefrontal cortex to acute handling stress were evaluated using in vivo microdialysis. Results: Acute handling stress increased dopamine and noradrenaline levels in the prefrontal cortex. The dopamine and noradrenaline responses were suppressed by local infusion of a 5-HT1A receptor agonist, 7-(Dipropylamino)-5,6,7,8-tetrahydronaphthalen-1-ol;hydrobromide, into the prefrontal cortex. The dopamine response was abolished by long-term treatment with citalopram, and the abolished dopamine response was reversed by local infusion of a 5-HT1A receptor antagonist, (Z)-but-2-enedioic acid;N-[2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-pyridin-2-ylcyclohexanecarboxamide into the prefrontal cortex. On the other hand, long-term treatment with citalopram reduced the basal noradrenaline levels (approximately 40% of the controls), but not the basal dopamine levels. The noradrenaline response was maintained despite the low basal noradrenaline levels. Signaling from the 5-HT1A receptors and α2-adrenoceptors was not involved in the decrease in the basal noradrenaline levels but partially affected the noradrenaline response. Conclusions: Chronic citalopram treatment differentially suppresses the dopamine and noradrenaline systems in the prefrontal cortex, and the dopamine stress response was preferentially controlled by upregulating 5-HT1A receptor signaling. Our findings provide insight into how antidepressants modulate the dopamine and noradrenaline systems to overcome acute stress. PMID

  3. Effects of Modafinil on Dopamine and Dopamine Transporters in the Male Human Brain: Clinical Implications

    PubMed Central

    Volkow, Nora D.; Fowler, Joanna S.; Logan, Jean; Alexoff, David; Zhu, Wei; Telang, Frank; Wang, Gene-Jack; Jayne, Millard; Hooker, Jacob M.; Wong, Christopher; Hubbard, Barbara; Carter, Pauline; Warner, Donald; King, Payton; Shea, Colleen; Xu, Youwen; Muench, Lisa; Apelskog-Torres, Karen

    2009-01-01

    Context Modafinil, a wake-promoting drug used to treat narcolepsy, is increasingly being used as a cognitive enhancer. Although initially launched as distinct from stimulants that increase extracellular dopamine by targeting dopamine transporters, recent preclinical studies suggest otherwise. Objective To measure the acute effects of modafinil at doses used therapeutically (200 mg and 400 mg given orally) on extracellular dopamine and on dopamine transporters in the male human brain. Design, Setting, and Participants Positron emission tomography with [11C]raclopride (D2/D3 radioligand sensitive to changes in endogenous dopamine) and [11C]cocaine (dopamine transporter radioligand) was used to measure the effects of modafinil on extracellular dopamine and on dopamine transporters in 10 healthy male participants. The study took place over an 8-month period (2007–2008) at Brookhaven National Laboratory. Main Outcome Measures Primary outcomes were changes in dopamine D2/D3 receptor and dopamine transporter availability (measured by changes in binding potential) after modafinil when compared with after placebo. Results Modafinil decreased mean (SD) [11C]raclopride binding potential in caudate (6.1% [6.5%]; 95% confidence interval [CI], 1.5% to 10.8%; P=.02), putamen (6.7% [4.9%]; 95% CI, 3.2% to 10.3%; P=.002), and nucleus accumbens (19.4% [20%]; 95% CI, 5% to 35%; P=.02), reflecting increases in extracellular dopamine. Modafinil also decreased [11C]cocaine binding potential in caudate (53.8% [13.8%]; 95% CI, 43.9% to 63.6%; P<.001), putamen (47.2% [11.4%]; 95% CI, 39.1% to 55.4%; P<.001), and nucleus accumbens (39.3% [10%]; 95% CI, 30% to 49%; P=.001), reflecting occupancy of dopamine transporters. Conclusions In this pilot study, modafinil blocked dopamine transporters and increased dopamine in the human brain (including the nucleus accumbens). Because drugs that increase dopamine in the nucleus accumbens have the potential for abuse, and considering the increasing

  4. In-silico analysis for RNA-interference mechanism of α-synuclein to treat Parkinson's disease.

    PubMed

    Seema, S; Seenivasagam, R; Hemavathi, K

    2013-01-01

    Parkinson's Disease (PD) causing mutations in α-synuclein gene are ALA30PRO, GLU46LYS and ALA53THR. The conformational changes in proteins with respect to all the three mutations were analysed. These were used to predict the structures of Short Interfering RNA (siRNA) antisense strand and siRNA region. The siRNA binds with the argonaute protein forming RNA Induced Silencing Complex (RISC). Then, siRNA antisense-strand was attached to RISC. The structure of dicer (RNase-III-enzyme) cleaves double-stranded RNA (dsRNA) into two siRNA-strands. Incorporation of single siRNA-strand into RISC guides to pair with the complementary α-synuclein target-messenger RNA (mRNA) thereby enabling it to cleave the target.

  5. The Aversive Agent Lithium Chloride Suppresses Phasic Dopamine Release Through Central GLP-1 Receptors.

    PubMed

    Fortin, Samantha M; Chartoff, Elena H; Roitman, Mitchell F

    2016-02-01

    Unconditioned rewarding stimuli evoke phasic increases in dopamine concentration in the nucleus accumbens (NAc) while discrete aversive stimuli elicit pauses in dopamine neuron firing and reductions in NAc dopamine concentration. The unconditioned effects of more prolonged aversive states on dopamine release dynamics are not well understood and are investigated here using the malaise-inducing agent lithium chloride (LiCl). We used fast-scan cyclic voltammetry to measure phasic increases in NAc dopamine resulting from electrical stimulation of dopamine cell bodies in the ventral tegmental area (VTA). Systemic LiCl injection reduced electrically evoked dopamine release in the NAc of both anesthetized and awake rats. As some behavioral effects of LiCl appear to be mediated through glucagon-like peptide-1 receptor (GLP-1R) activation, we hypothesized that the suppression of phasic dopamine by LiCl is GLP-1R dependent. Indeed, peripheral pretreatment with the GLP-1R antagonist exendin-9 (Ex-9) potently attenuated the LiCl-induced suppression of dopamine. Pretreatment with Ex-9 did not, however, affect the suppression of phasic dopamine release by the kappa-opioid receptor agonist, salvinorin A, supporting a selective effect of GLP-1R stimulation in LiCl-induced dopamine suppression. By delivering Ex-9 to either the lateral or fourth ventricle, we highlight a population of central GLP-1 receptors rostral to the hindbrain that are involved in the LiCl-mediated suppression of NAc dopamine release.

  6. Failure to find linkage between a functional polymorphism in the dopamine D4 receptor gene and schizophrenia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shaikh, S.; Gill, M.; Collier, D.A.

    1994-03-15

    We report the results of a linkage study in 24 families multiply affected with schizophrenia using a polymorphic DNA sequence encoding the third cytoplasmic loop of the dopamine D4 receptor. Two-point LOD score analyses with a range of single gene models ranging from near dominant to near recessive revealed no evidence for linkage. In addition, we examined the data by non-parametric sib-pair analysis and found no excess sharing of alleles between affected sib-pairs. We therefore conclude that mutations within the dopamine D4 receptor gene do not have a major aetiological role in schizophrenia in our collection of pedigrees. 20 refs.,more » 2 tabs.« less

  7. Structure based aggregation studies reveal the presence of helix-rich intermediate during α-Synuclein aggregation

    PubMed Central

    Ghosh, Dhiman; Singh, Pradeep K.; Sahay, Shruti; Jha, Narendra Nath; Jacob, Reeba S.; Sen, Shamik; Kumar, Ashutosh; Riek, Roland; Maji, Samir K.

    2015-01-01

    Mechanistic understanding of nucleation dependent polymerization by α-synuclein (α-Syn) into toxic oligomers and amyloids is important for the drug development against Parkinson's disease. However the structural and morphological characterization during nucleation and subsequent fibrillation process of α-Syn is not clearly understood. Using a variety of complementary biophysical techniques monitoring entire pathway of nine different synucleins, we found that transition of unstructured conformation into β-sheet rich fibril formation involves helix-rich intermediates. These intermediates are common for all aggregating synucleins, contain high solvent-exposed hydrophobic surfaces, are cytotoxic to SHSY-5Y cells and accelerate α-Syn aggregation efficiently. A multidimensional NMR study characterizing the intermediate accompanied with site-specific fluorescence study suggests that the N-terminal and central portions mainly participate in the helix-rich intermediate formation while the C-terminus remained in an extended conformation. However, significant conformational transitions occur at the middle and at the C-terminus during helix to β-sheet transition as evident from Trp fluorescence study. Since partial helix-rich intermediates were also observed for other amyloidogenic proteins such as Aβ and IAPP, we hypothesize that this class of intermediates may be one of the important intermediates for amyloid formation pathway by many natively unstructured protein/peptides and represent a potential target for drug development against amyloid diseases. PMID:25784353

  8. Switch from excitatory to inhibitory actions of ethanol on dopamine levels after chronic exposure: Role of kappa opioid receptors

    PubMed Central

    Karkhanis, Anushree N.; Huggins, Kimberly N.; Rose, Jamie H.; Jones, Sara R.

    2016-01-01

    Acute ethanol exposure is known to stimulate the dopamine system; however, chronic exposure has been shown to downregulate the dopamine system. In rodents, chronic intermittent exposure (CIE) to ethanol also increases negative affect during withdrawal, such as, increases in anxiety- and depressive-like behavior. Moreover, CIE exposure results in increased ethanol drinking and preference during withdrawal. Previous literature documents reductions in CIE-induced anxiety-, depressive-like behaviors and ethanol intake in response to kappa opioid receptor (KOR) blockade. KORs are located on presynaptic dopamine terminals in the nucleus accumbens (NAc) and inhibit release, an effect which has been linked to negative affective behaviors. Previous reports show an upregulation in KOR function following extended CIE exposure; however it is not clear whether there is a direct link between KOR upregulation and dopamine downregulation during withdrawal from CIE. This study aimed to examine the effects of KOR modulation on dopamine responses to ethanol of behaving mice exposed to air or ethanol vapor in a repeated intermittent pattern. First, we showed that KORs have a greater response to an agonist after moderate CIE compared to air exposed mice using ex vivo fast scan cyclic voltammetry. Second, using in vivo microdialysis, we showed that, in contrast to the expected increase in extracellular levels of dopamine following an acute ethanol challenge in air exposed mice, CIE exposed mice exhibited a robust decrease in dopamine levels. Third, we showed that blockade of KORs reversed the aberrant inhibitory dopamine response to ethanol in CIE exposed mice while not affecting the air exposed mice demonstrating that inhibition of KORs “rescued” dopamine responses in CIE exposed mice. Taken together, these findings indicate that augmentation of dynorphin/KOR system activity drives the reduction in stimulated (electrical and ethanol) dopamine release in the NAc. Thus, blockade of

  9. Dopamine Modulates Delta-Gamma Phase-Amplitude Coupling in the Prefrontal Cortex of Behaving Rats.

    PubMed

    Andino-Pavlovsky, Victoria; Souza, Annie C; Scheffer-Teixeira, Robson; Tort, Adriano B L; Etchenique, Roberto; Ribeiro, Sidarta

    2017-01-01

    Dopamine release and phase-amplitude cross-frequency coupling (CFC) have independently been implicated in prefrontal cortex (PFC) functioning. To causally investigate whether dopamine release affects phase-amplitude comodulation between different frequencies in local field potentials (LFP) recorded from the medial PFC (mPFC) of behaving rats, we used RuBiDopa, a light-sensitive caged compound that releases the neurotransmitter dopamine when irradiated with visible light. LFP power did not change in any frequency band after the application of light-uncaged dopamine, but significantly strengthened phase-amplitude comodulation between delta and gamma oscillations. Saline did not exert significant changes, while injections of dopamine and RuBiDopa produced a slow increase in comodulation for several minutes after the injection. The results show that dopamine release in the medial PFC shifts phase-amplitude comodulation from theta-gamma to delta-gamma. Although being preliminary results due to the limitation of the low number of animals present in this study, our findings suggest that dopamine-mediated modification of the frequencies involved in comodulation could be a mechanism by which this neurotransmitter regulates functioning in mPFC.

  10. Bridging the gap between high-throughput genetic and transcriptional data reveals cellular pathways responding to alpha-synuclein toxicity

    PubMed Central

    Yeger-Lotem, Esti; Riva, Laura; Su, Linhui Julie; Gitler, Aaron D.; Cashikar, Anil; King, Oliver D.; Auluck, Pavan K.; Geddie, Melissa L.; Valastyan, Julie S.; Karger, David R.; Lindquist, Susan; Fraenkel, Ernest

    2009-01-01

    Cells respond to stimuli by changes in various processes, including signaling pathways and gene expression. Efforts to identify components of these responses increasingly depend on mRNA profiling and genetic library screens, yet the functional roles of the genes identified by these assays often remain enigmatic. By comparing the results of these two assays across various cellular responses, we found that they are consistently distinct. Moreover, genetic screens tend to identify response regulators, while mRNA profiling frequently detects metabolic responses. We developed an integrative approach that bridges the gap between these data using known molecular interactions, thus highlighting major response pathways. We harnessed this approach to reveal cellular pathways related to alpha-synuclein, a small lipid-binding protein implicated in several neurodegenerative disorders including Parkinson disease. For this we screened an established yeast model for alpha-synuclein toxicity to identify genes that when overexpressed alter cellular survival. Application of our algorithm to these data and data from mRNA profiling provided functional explanations for many of these genes and revealed novel relations between alpha-synuclein toxicity and basic cellular pathways. PMID:19234470

  11. Midbrain dopamine neurons signal aversion in a reward-context-dependent manner

    PubMed Central

    Matsumoto, Hideyuki; Tian, Ju; Uchida, Naoshige; Watabe-Uchida, Mitsuko

    2016-01-01

    Dopamine is thought to regulate learning from appetitive and aversive events. Here we examined how optogenetically-identified dopamine neurons in the lateral ventral tegmental area of mice respond to aversive events in different conditions. In low reward contexts, most dopamine neurons were exclusively inhibited by aversive events, and expectation reduced dopamine neurons’ responses to reward and punishment. When a single odor predicted both reward and punishment, dopamine neurons’ responses to that odor reflected the integrated value of both outcomes. Thus, in low reward contexts, dopamine neurons signal value prediction errors (VPEs) integrating information about both reward and aversion in a common currency. In contrast, in high reward contexts, dopamine neurons acquired a short-latency excitation to aversive events that masked their VPE signaling. Our results demonstrate the importance of considering the contexts to examine the representation in dopamine neurons and uncover different modes of dopamine signaling, each of which may be adaptive for different environments. DOI: http://dx.doi.org/10.7554/eLife.17328.001 PMID:27760002

  12. Alpha-Synuclein: From Early Synaptic Dysfunction to Neurodegeneration.

    PubMed

    Ghiglieri, Veronica; Calabrese, Valeria; Calabresi, Paolo

    2018-01-01

    Over the last two decades, many experimental and clinical studies have provided solid evidence that alpha-synuclein (α-syn), a small, natively unfolded protein, is closely related to Parkinson's disease (PD) pathology. To provide an overview on the different roles of this protein, here we propose a synopsis of seminal and recent studies that explored the many aspects of α-syn. Ranging from the physiological functions to its neurodegenerative potential, the relationship with the possible pathogenesis of PD will be discussed. Close attention will be paid on early cellular and molecular alterations associated with the presence of α-syn aggregates.

  13. Orbitofrontal Dopamine Depletion Upregulates Caudate Dopamine and Alters Behavior via Changes in Reinforcement Sensitivity

    PubMed Central

    Cardinal, R. N.; Rygula, R.; Hong, Y. T.; Fryer, T. D.; Sawiak, S. J.; Ferrari, V.; Cockcroft, G.; Aigbirhio, F. I.; Robbins, T. W.; Roberts, A. C.

    2014-01-01

    Schizophrenia is associated with upregulation of dopamine (DA) release in the caudate nucleus. The caudate has dense connections with the orbitofrontal cortex (OFC) via the frontostriatal loops, and both areas exhibit pathophysiological change in schizophrenia. Despite evidence that abnormalities in dopaminergic neurotransmission and prefrontal cortex function co-occur in schizophrenia, the influence of OFC DA on caudate DA and reinforcement processing is poorly understood. To test the hypothesis that OFC dopaminergic dysfunction disrupts caudate dopamine function, we selectively depleted dopamine from the OFC of marmoset monkeys and measured striatal extracellular dopamine levels (using microdialysis) and dopamine D2/D3 receptor binding (using positron emission tomography), while modeling reinforcement-related behavior in a discrimination learning paradigm. OFC dopamine depletion caused an increase in tonic dopamine levels in the caudate nucleus and a corresponding reduction in D2/D3 receptor binding. Computational modeling of behavior showed that the lesion increased response exploration, reducing the tendency to persist with a recently chosen response side. This effect is akin to increased response switching previously seen in schizophrenia and was correlated with striatal but not OFC D2/D3 receptor binding. These results demonstrate that OFC dopamine depletion is sufficient to induce striatal hyperdopaminergia and changes in reinforcement learning relevant to schizophrenia. PMID:24872570

  14. Deep dopamine extravasation injury: a case report.

    PubMed

    Phillips, Reid A; Andrades, Patricio; Grant, John H; Ray, Peter D

    2009-07-01

    We report the case of a 3-month-old girl with Down's syndrome, who sustained a deep and massive extravasation of dopamine, resulting in segmented, full-thickness skin necrosis and transient brachial plexus palsy of her left upper extremity. The patient was managed conservatively, including wound care, de-bridement of necrotic tissue, secondary wound healing and intensive physical therapy. The patient showed a satisfactory outcome with complete secondary closure of her wounds and full brachial plexus recovery after 1 year of follow-up. The mechanism of action of dopamine in the deep soft tissue, the difficulties of an adequate diagnosis of a deep dopamine extravasation and alternative treatments are presented in this article.

  15. Effects of Dopamine Donor Pretreatment on Graft Survival after Kidney Transplantation: A Randomized Trial.

    PubMed

    Schnuelle, Peter; Schmitt, Wilhelm H; Weiss, Christel; Habicht, Antje; Renders, Lutz; Zeier, Martin; Drüschler, Felix; Heller, Katharina; Pisarski, Przemyslaw; Banas, Bernhard; Krämer, Bernhard K; Jung, Matthias; Lopau, Kai; Olbricht, Christoph J; Weihprecht, Horst; Schenker, Peter; De Fijter, Johan W; Yard, Benito A; Benck, Urs

    2017-03-07

    Donor dopamine improves initial graft function after kidney transplantation due to antioxidant properties. We investigated if a 4 µ g/kg per minute continuous dopamine infusion administered after brain-death confirmation affects long-term graft survival and examined the exposure-response relationship with treatment duration. Five-year follow-up of 487 renal transplant patients from 60 European centers who had participated in the randomized, multicenter trial of dopamine donor pretreatment between 2004 and 2007 (ClinicalTrials.gov identifier: NCT00115115). Follow-up was complete in 99.2%. Graft survival was 72.6% versus 68.7% ( P =0.34), and 83.3% versus 80.4% ( P =0.42) after death-censoring in treatment and control arms according to trial assignment. Although infusion times varied substantially in the treatment arm (range 0-32.2 hours), duration of the dopamine infusion and all-cause graft failure exhibited an exposure-response relationship (hazard ratio, 0.96; 95% confidence interval [95% CI], 0.92 to 1.00, per hour). Cumulative frequency curves of graft survival and exposure time of the dopamine infusion indicated a maximum response rate at 7.10 hours (95% CI, 6.99 to 7.21), which almost coincided with the optimum infusion time for improvement of early graft function (7.05 hours; 95% CI, 6.92 to 7.18). Taking infusion time of 7.1 hours as threshold in subsequent graft survival analyses indicated a relevant benefit: Overall, 81.5% versus 68.5%; P =0.03; and 90.3% versus 80.2%; P =0.04 after death-censoring. We failed to show a significant graft survival advantage on intention-to-treat. Dopamine infusion time was very short in a considerable number of donors assigned to treatment. Our finding of a significant, nonlinear exposure-response relationship disclosed a threshold value of the dopamine infusion time that may improve long-term kidney graft survival. Copyright © 2017 by the American Society of Nephrology.

  16. Dynamic nigrostriatal dopamine biases action selection

    PubMed Central

    Howard, Christopher D.; Li, Hao; Geddes, Claire E.; Jin, Xin

    2017-01-01

    Summary Dopamine is thought to play a critical role in reinforcement learning and goal-directed behavior, but its function in action selection remains largely unknown. Here, we demonstrate that nigrostriatal dopamine biases ongoing action selection. When mice were trained to dynamically switch the action selected at different time points, changes in firing rate of nigrostriatal dopamine neurons, as well as dopamine signaling in the dorsal striatum, were found to be associated with action selection. This dopamine profile is specific to behavioral choice, scalable with interval duration, and doesn’t reflect reward prediction error, timing, or value as single factors alone. Genetic deletion of NMDA receptors on dopamine or striatal neurons, or optogenetic manipulation of dopamine concentration, alters dopamine signaling and biases action selection. These results unveil a crucial role of nigrostriatal dopamine in integrating diverse information for regulating upcoming actions and have important implications for neurological disorders including Parkinson’s disease and substance dependence. PMID:28285820

  17. Dynamic Nigrostriatal Dopamine Biases Action Selection.

    PubMed

    Howard, Christopher D; Li, Hao; Geddes, Claire E; Jin, Xin

    2017-03-22

    Dopamine is thought to play a critical role in reinforcement learning and goal-directed behavior, but its function in action selection remains largely unknown. Here we demonstrate that nigrostriatal dopamine biases ongoing action selection. When mice were trained to dynamically switch the action selected at different time points, changes in firing rate of nigrostriatal dopamine neurons, as well as dopamine signaling in the dorsal striatum, were found to be associated with action selection. This dopamine profile is specific to behavioral choice, scalable with interval duration, and doesn't reflect reward prediction error, timing, or value as single factors alone. Genetic deletion of NMDA receptors on dopamine or striatal neurons or optogenetic manipulation of dopamine concentration alters dopamine signaling and biases action selection. These results unveil a crucial role of nigrostriatal dopamine in integrating diverse information for regulating upcoming actions, and they have important implications for neurological disorders, including Parkinson's disease and substance dependence. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. The dopamine beta-hydroxylase inhibitor nepicastat increases dopamine release and potentiates psychostimulant-induced dopamine release in the prefrontal cortex.

    PubMed

    Devoto, Paola; Flore, Giovanna; Saba, Pierluigi; Bini, Valentina; Gessa, Gian Luigi

    2014-07-01

    The dopamine-beta-hydroxylase inhibitor nepicastat has been shown to reproduce disulfiram ability to suppress the reinstatement of cocaine seeking after extinction in rats. To clarify its mechanism of action, we examined the effect of nepicastat, given alone or in association with cocaine or amphetamine, on catecholamine release in the medial prefrontal cortex and the nucleus accumbens, two key regions involved in the reinforcing and motivational effects of cocaine and in the reinstatement of cocaine seeking. Nepicastat effect on catecholamines was evaluated by microdialysis in freely moving rats. Nepicastat reduced noradrenaline release both in the medial prefrontal cortex and in the nucleus accumbens, and increased dopamine release in the medial prefrontal cortex but not in the nucleus accumbens. Moreover, nepicastat markedly potentiated cocaine- and amphetamine-induced extracellular dopamine accumulation in the medial prefrontal cortex but not in the nucleus accumbens. Extracellular dopamine accumulation produced by nepicastat alone or by its combination with cocaine or amphetamine was suppressed by the α2 -adrenoceptor agonist clonidine. It is suggested that nepicastat, by suppressing noradrenaline synthesis and release, eliminated the α2 -adrenoceptor mediated inhibitory mechanism that constrains dopamine release and cocaine- and amphetamine-induced dopamine release from noradrenaline or dopamine terminals in the medial prefrontal cortex. © 2012 The Authors, Addiction Biology © 2012 Society for the Study of Addiction.

  19. The heterozygous A53T mutation in the alpha-synuclein gene in a Chinese Han patient with Parkinson disease: case report and literature review.

    PubMed

    Xiong, Wei-Xi; Sun, Yi-Min; Guan, Rong-Yuan; Luo, Su-Shan; Chen, Chen; An, Yu; Wang, Jian; Wu, Jian-Jun

    2016-10-01

    The missense mutation A53T of alpha-synuclein gene (SNCA) was reported to be a rare but definite cause of sporadic and familial Parkinson disease (PD). It seemed to be restricted geographically in Greece and Italy. We aimed to identify the SNCA mutations in a Chinese PD cohort. Ninety-one early onset PD patients or familial PD probands were collected consecutively for the screening of PD-related genes. The genetic analysis was carried out by target sequencing of the exons and the corresponding flanking regions of the PD-related genes using Illumina HiSeq 2000 sequencer and further confirmed by Sanger sequencing or restriction fragment length polymorphism. Dosage mutations of exons in these genes were carried out by multiple ligation-dependent probe amplification. Among the 91 patients, we found only one heterozygous mutation of SNCA A53T, in a 23-year-old male patient with negative family history. The [(11)C]-2β-carbomethoxy-3β-(4-fluorophenyl) tropan (CFT) PET and PD-related spatial covariance pattern (PDRP) via [(18)F]-fluorodeoxyglucos (FDG) PET confirmed a typical pattern of PD. After examining his parents, we found his mother was an asymptomatic carrier, with declined hand dexterity detected by quantitative motor tests. Reduced dopamine transporter uptake of his mother was identified by CFT PET, and abnormal PDRP pattern was found by FDG PET. Our investigation expanded the clinical and genetic spectrum of Chinese PD patients, and we suggested SNCA mutations to be screened in familial and early onset Chinese PD patients.

  20. Nicotine-induced Conditional Place Preference is Affected by Head Injury: Correlation with Dopamine Release in the Nucleus Accumbens Shell.

    PubMed

    Yuan-Hao, Chen; Kuo, Tung-Tai; Huang, Eagle Yi-Kung; Hoffer, Barry J; Kao, Jen-Hsin; Chou, Yu-Ching; Chiang, Yung-Hsiao; Miller, Jonathan

    2018-06-14

    Traumatic brain injury (TBI) is known to impact dopamine-mediated reward pathways, but the underlying mechanisms have not been fully established. Nicotine-induced conditional place preference (CPP) was used to study rats exposed to a 6-psi fluid percussion injury (FPI) with and without prior exposure to nicotine. Preference was quantified as a score defined as (C1-C2) / (C1+C2), where C1 is time in the nicotine-paired compartment and C2 is time in the saline-paired compartment. Subsequent fast-scan cyclic voltammetry (FSCV) was used to analyze the impact of nicotine infusion on dopamine release in the shell portion of the nucleus accumbens (NAc). To further determine the influence of brain injury on nicotine withdrawal, nicotine infusion was administered to the rats after FPI. The effects of FPI on CPP after prior exposure to nicotine and abstinence or withdrawal from nicotine were also assessed. After TBI, dopamine release was reduced in the NAc shell, and nicotine-induced CPP preference was significantly impaired. Preference scores of control, sham-injured, and FPI groups were 0.1627 ± 0.04204, 0.1515 ± 0.03806, and -0.001300 ± 0.04286, respectively. Nicotine-induced CPP was also seen in animals after nicotine pre-treatment, with a CPP score of 0.07805 ± 0.02838. Nicotine pre-exposure substantially increased tonic dopamine release in sham-injured animals, but it did not change phasic release; nicotine exposure after FPI enhanced phasic release, though not to the same levels seen in sham-injured rats. Conditioned preference was related not only to phasic dopamine release (r= 0.8110) but also to the difference between tonic and phasic dopamine levels (r= 0.9521). TBI suppresses dopamine release from the shell portion of the NAc, which in turn significantly alters reward-seeking behavior. These results have important implications for tobacco and drug use after TBI.

  1. Direct and Systemic Administration of a CNS-Permeant Tamoxifen Analog Reduces Amphetamine-Induced Dopamine Release and Reinforcing Effects.

    PubMed

    Carpenter, Colleen; Zestos, Alexander G; Altshuler, Rachel; Sorenson, Roderick J; Guptaroy, Bipasha; Showalter, Hollis D; Kennedy, Robert T; Jutkiewicz, Emily; Gnegy, Margaret E

    2017-09-01

    Amphetamines (AMPHs) are globally abused. With no effective treatment for AMPH addiction to date, there is urgent need for the identification of druggable targets that mediate the reinforcing action of this stimulant class. AMPH-stimulated dopamine efflux is modulated by protein kinase C (PKC) activation. Inhibition of PKC reduces AMPH-stimulated dopamine efflux and locomotor activity. The only known CNS-permeant PKC inhibitor is the selective estrogen receptor modulator tamoxifen. In this study, we demonstrate that a tamoxifen analog, 6c, which more potently inhibits PKC than tamoxifen but lacks affinity for the estrogen receptor, reduces AMPH-stimulated increases in extracellular dopamine and reinforcement-related behavior. In rat striatal synaptosomes, 6c was almost fivefold more potent at inhibiting AMPH-stimulated dopamine efflux than [ 3 H]dopamine uptake through the dopamine transporter (DAT). The compound did not compete with [ 3 H]WIN 35,428 binding or affect surface DAT levels. Using microdialysis, direct accumbal administration of 1 μM 6c reduced dopamine overflow in freely moving rats. Using LC-MS, we demonstrate that 6c is CNS-permeant. Systemic treatment of rats with 6 mg/kg 6c either simultaneously or 18 h prior to systemic AMPH administration reduced both AMPH-stimulated dopamine overflow and AMPH-induced locomotor effects. Finally, 18 h pretreatment of rats with 6 mg/kg 6c s.c. reduces AMPH-self administration but not food self-administration. These results demonstrate the utility of tamoxifen analogs in reducing AMPH effects on dopamine and reinforcement-related behaviors and suggest a new avenue of development for therapeutics to reduce AMPH abuse.

  2. Activation of D1/5 Dopamine Receptors: A Common Mechanism for Enhancing Extinction of Fear and Reward-Seeking Behaviors.

    PubMed

    Abraham, Antony D; Neve, Kim A; Lattal, K Matthew

    2016-07-01

    Dopamine is critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine's function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in appetitive tasks. A parallel and growing literature indicates that dopamine signaling is involved in consolidation of memories into stable representations in aversive tasks such as fear conditioning. Relatively little is known about how dopamine may modulate memories that form during extinction, when organisms learn that the relation between previously associated events is severed. We investigated whether fear and reward extinction share common mechanisms that could be enhanced with dopamine D1/5 receptor activation. Pharmacological activation of dopamine D1/5 receptors (with SKF 81297) enhanced extinction of both cued and contextual fear. These effects also occurred in the extinction of cocaine-induced conditioned place preference, suggesting that the observed effects on extinction were not specific to a particular type of procedure (aversive or appetitive). A cAMP/PKA biased D1 agonist (SKF 83959) did not affect fear extinction, whereas a broadly efficacious D1 agonist (SKF 83822) promoted fear extinction. Together, these findings show that dopamine D1/5 receptor activation is a target for the enhancement of fear or reward extinction.

  3. Glutamatergic modulation of hyperactivity in mice lacking the dopamine transporter

    PubMed Central

    Gainetdinov, Raul R.; Mohn, Amy R.; Bohn, Laura M.; Caron, Marc G.

    2001-01-01

    In the brain, dopamine exerts an important modulatory influence over behaviors such as emotion, cognition, and affect as well as mechanisms of reward and the control of locomotion. The dopamine transporter (DAT), which reuptakes the released neurotransmitter into presynaptic terminals, is a major determinant of the intensity and duration of the dopaminergic signal. Knockout mice lacking the dopamine transporter (DAT-KO mice) display marked changes in dopamine homeostasis that result in elevated dopaminergic tone and pronounced locomotor hyperactivity. A feature of DAT-KO mice is that their hyperactivity can be inhibited by psychostimulants and serotonergic drugs. The pharmacological effect of these drugs occurs without any observable changes in dopaminergic parameters, suggesting that other neurotransmitter systems in addition to dopamine might contribute to the control of locomotion in these mice. We report here that the hyperactivity of DAT-KO mice can be markedly further enhanced when N-methyl-d-aspartate receptor-mediated glutamatergic transmission is blocked. Conversely, drugs that enhance glutamatergic transmission, such as positive modulators of l-α-amino-3-hydroxy-5-methylisoxazole-4-propionate glutamate receptors, suppress the hyperactivity of DAT-KO mice. Interestingly, blockade of N- methyl-d-aspartate receptors prevented the inhibitory effects of both psychostimulant and serotonergic drugs on hyperactivity. These findings support the concept of a reciprocal functional interaction between dopamine and glutamate in the basal ganglia and suggest that agents modulating glutamatergic transmission may represent an approach to manage conditions associated with dopaminergic dysfunction. PMID:11572967

  4. Reward-based hypertension control by a synthetic brain-dopamine interface.

    PubMed

    Rössger, Katrin; Charpin-El Hamri, Ghislaine; Fussenegger, Martin

    2013-11-05

    Synthetic biology has significantly advanced the design of synthetic trigger-controlled devices that can reprogram mammalian cells to interface with complex metabolic activities. In the brain, the neurotransmitter dopamine coordinates communication with target neurons via a set of dopamine receptors that control behavior associated with reward-driven learning. This dopamine transmission has recently been suggested to increase central sympathetic outflow, resulting in plasma dopamine levels that correlate with corresponding brain activities. By functionally rewiring the human dopamine receptor D1 (DRD1) via the second messenger cyclic adenosine monophosphate (cAMP) to synthetic promoters containing cAMP response element-binding protein 1(CREB1)-specific cAMP-responsive operator modules, we have designed a synthetic dopamine-sensitive transcription controller that reversibly fine-tunes specific target gene expression at physiologically relevant brain-derived plasma dopamine levels. Following implantation of circuit-transgenic human cell lines insulated by semipermeable immunoprotective microcontainers into mice, the designer device interfaced with dopamine-specific brain activities and produced a systemic expression response when the animal's reward system was stimulated by food, sexual arousal, or addictive drugs. Reward-triggered brain activities were able to remotely program peripheral therapeutic implants to produce sufficient amounts of the atrial natriuretic peptide, which reduced the blood pressure of hypertensive mice to the normal physiologic range. Seamless control of therapeutic transgenes by subconscious behavior may provide opportunities for treatment strategies of the future.

  5. Dopamine Modulates Delta-Gamma Phase-Amplitude Coupling in the Prefrontal Cortex of Behaving Rats

    PubMed Central

    Andino-Pavlovsky, Victoria; Souza, Annie C.; Scheffer-Teixeira, Robson; Tort, Adriano B. L.; Etchenique, Roberto; Ribeiro, Sidarta

    2017-01-01

    Dopamine release and phase-amplitude cross-frequency coupling (CFC) have independently been implicated in prefrontal cortex (PFC) functioning. To causally investigate whether dopamine release affects phase-amplitude comodulation between different frequencies in local field potentials (LFP) recorded from the medial PFC (mPFC) of behaving rats, we used RuBiDopa, a light-sensitive caged compound that releases the neurotransmitter dopamine when irradiated with visible light. LFP power did not change in any frequency band after the application of light-uncaged dopamine, but significantly strengthened phase-amplitude comodulation between delta and gamma oscillations. Saline did not exert significant changes, while injections of dopamine and RuBiDopa produced a slow increase in comodulation for several minutes after the injection. The results show that dopamine release in the medial PFC shifts phase-amplitude comodulation from theta-gamma to delta-gamma. Although being preliminary results due to the limitation of the low number of animals present in this study, our findings suggest that dopamine-mediated modification of the frequencies involved in comodulation could be a mechanism by which this neurotransmitter regulates functioning in mPFC. PMID:28536507

  6. Comparative Analysis of the Conformation, Aggregation, Interaction, and Fibril Morphologies of Human α-, β-, and γ-Synuclein Proteins.

    PubMed

    Jain, Manish Kumar; Singh, Priyanka; Roy, Sneha; Bhat, Rajiv

    2018-06-13

    The human synuclein (syn) family is comprised of α-, β-, and γ-syn proteins. α-syn has the highest propensity for aggregation, and its aggregated forms accumulate in Lewy bodies (LB) and Lewy neurites, which are involved in Parkinson's disease (PD). β- and γ-syn are absent in LB, and their exact role is still enigmatic. β-syn does not form aggregates under physiological conditions (pH 7.4), while γ-syn is associated with neural and non-neural diseases like breast cancer. Because of their similar regional distribution in the brain, natively unfolded structure, and high degree of sequence homology, studying the effect of the environment on their conformation, interactions, fibrillation, and fibril morphologies has become important. Our studies show that high temperatures, low pH values, and high concentrations increase the rate of fibrillation of α- and γ-syn, while β-syn forms fibrils only at low pH. Fibril morphologies are strongly dependent on the immediate environment of the proteins. The high molar ratio of β-syn inhibits the fibrillation in α- and γ-syn. However, preformed seed fibrils of β- and γ-syn do not affect fibrillation of α-syn. Surface plasmon resonance data show that interactions between α- and β-syn, β- and γ-syn, and α- and γ-syn are weak to moderate in nature and can be physiologically significant in counteracting several adverse conditions in the cells that trigger their aggregation. These studies could be helpful in understanding collective human synuclein behavior in various protein environments and in the modulation of the homeostasis between β-syn and healthy versus corrupt α- and γ-syn that can potentially affect PD pathology.

  7. Aggregation of alpha-synuclein by a coarse-grained Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Farmer, Barry; Pandey, Ras

    Alpha-synuclein, an intrinsic protein abundant in neurons, is believed to be a major cause of neurodegenerative diseases (e.g. Alzheimer, Parkinson's disease). Abnormal aggregation of ASN leads to Lewy bodies with specific morphologies. We investigate the self-organizing structures in a crowded environment of ASN proteins by a coarse-grained Monte Carlo simulation. ASN is a chain of 140 residues. Structure detail of residues is neglected but its specificity is captured via unique knowledge-based residue-residue interactions. Large-scale simulations are performed to analyze a number local and global physical quantities (e.g. mobility profile, contact map, radius of gyration, structure factor) as a function of temperature and protein concentration. Trend in multi-scale structural variations of the protein in a crowded environment is compared with that of a free protein chain.

  8. The Role of Genes, Stress, and Dopamine in the Development of Schizophrenia.

    PubMed

    Howes, Oliver D; McCutcheon, Robert; Owen, Michael J; Murray, Robin M

    2017-01-01

    The dopamine hypothesis is the longest standing pathoetiologic theory of schizophrenia. Because it was initially based on indirect evidence and findings in patients with established schizophrenia, it was unclear what role dopamine played in the onset of the disorder. However, recent studies in people at risk of schizophrenia have found elevated striatal dopamine synthesis capacity and increased dopamine release to stress. Furthermore, striatal dopamine changes have been linked to altered cortical function during cognitive tasks, in line with preclinical evidence that a circuit involving cortical projections to the striatum and midbrain may underlie the striatal dopamine changes. Other studies have shown that a number of environmental risk factors for schizophrenia, such as social isolation and childhood trauma, also affect presynaptic dopaminergic function. Advances in preclinical work and genetics have begun to unravel the molecular architecture linking dopamine, psychosis, and psychosocial stress. Included among the many genes associated with risk of schizophrenia are the gene encoding the dopamine D 2 receptor and those involved in the upstream regulation of dopaminergic synthesis, through glutamatergic and gamma-aminobutyric acidergic pathways. A number of these pathways are also linked to the stress response. We review these new lines of evidence and present a model of how genes and environmental factors may sensitize the dopamine system so that it is vulnerable to acute stress, leading to progressive dysregulation and the onset of psychosis. Finally, we consider the implications for rational drug development, in particular regionally selective dopaminergic modulation, and the potential of genetic factors to stratify patients. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  9. Prefrontal and Striatal Glutamate Differently Relate to Striatal Dopamine: Potential Regulatory Mechanisms of Striatal Presynaptic Dopamine Function?

    PubMed

    Gleich, Tobias; Deserno, Lorenz; Lorenz, Robert Christian; Boehme, Rebecca; Pankow, Anne; Buchert, Ralph; Kühn, Simone; Heinz, Andreas; Schlagenhauf, Florian; Gallinat, Jürgen

    2015-07-01

    Theoretical and animal work has proposed that prefrontal cortex (PFC) glutamate inhibits dopaminergic inputs to the ventral striatum (VS) indirectly, whereas direct VS glutamatergic afferents have been suggested to enhance dopaminergic inputs to the VS. In the present study, we aimed to investigate relationships of glutamate and dopamine measures in prefrontostriatal circuitries of healthy humans. We hypothesized that PFC and VS glutamate, as well as their balance, are differently associated with VS dopamine. Glutamate concentrations in the left lateral PFC and left striatum were assessed using 3-Tesla proton magnetic resonance spectroscopy. Striatal presynaptic dopamine synthesis capacity was measured by fluorine-18-l-dihydroxyphenylalanine (F-18-FDOPA) positron emission tomography. First, a negative relationship was observed between glutamate concentrations in lateral PFC and VS dopamine synthesis capacity (n = 28). Second, a positive relationship was revealed between striatal glutamate and VS dopamine synthesis capacity (n = 26). Additionally, the intraindividual difference between PFC and striatal glutamate concentrations correlated negatively with VS dopamine synthesis capacity (n = 24). The present results indicate an involvement of a balance in PFC and striatal glutamate in the regulation of VS dopamine synthesis capacity. This notion points toward a potential mechanism how VS presynaptic dopamine levels are kept in a fine-tuned range. A disruption of this mechanism may account for alterations in striatal dopamine turnover as observed in mental diseases (e.g., in schizophrenia). The present work demonstrates complementary relationships between prefrontal and striatal glutamate and ventral striatal presynaptic dopamine using human imaging measures: a negative correlation between prefrontal glutamate and presynaptic dopamine and a positive relationship between striatal glutamate and presynaptic dopamine are revealed. The results may reflect a regulatory role

  10. Dopamine and extinction: a convergence of theory with fear and reward circuitry.

    PubMed

    Abraham, Antony D; Neve, Kim A; Lattal, K Matthew

    2014-02-01

    Research on dopamine lies at the intersection of sophisticated theoretical and neurobiological approaches to learning and memory. Dopamine has been shown to be critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine's function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in reward-related tasks. A parallel and growing literature indicates that dopamine is involved in fear conditioning and extinction. These studies are consistent with long-standing ideas about appetitive-aversive interactions in learning theory and they speak to the general nature of cellular and molecular processes that underlie behavior. We review the behavioral and neurobiological literature showing a role for dopamine in fear conditioning and extinction. At a cellular level, we review dopamine signaling and receptor pharmacology, cellular and molecular events that follow dopamine receptor activation, and brain systems in which dopamine functions. At a behavioral level, we describe theories of learning and dopamine function that could describe the fundamental rules underlying how dopamine modulates different aspects of learning and memory processes. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Rotenone and paraquat perturb dopamine metabolism: a computational analysis of pesticide toxicity

    PubMed Central

    Qi, Zhen; Miller, Gary W.; Voit, Eberhard O.

    2014-01-01

    Pesticides, such as rotenone and paraquat, are suspected in the pathogenesis of Parkinson’s disease (PD), whose hallmark is the progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Thus, compounds expected to play a role in the pathogenesis of PD will likely impact the function of dopaminergic neurons. To explore the relationship between pesticide exposure and dopaminergic toxicity, we developed a custom-tailored mathematical model of dopamine metabolism and utilized it to infer potential mechanisms underlying the toxicity of rotenone and paraquat, asking how these pesticides perturb specific processes. We performed two types of analyses, which are conceptually different and complement each other. The first analysis, a purely algebraic reverse engineering approach, analytically and deterministically computes the altered profile of enzyme activities that characterize the effects of a pesticide. The second method consists of large-scale Monte Carlo simulations that statistically reveal possible mechanisms of pesticides. The results from the reverse engineering approach show that rotenone and paraquat exposures lead to distinctly different flux perturbations. Rotenone seems to affect all fluxes associated with dopamine compartmentalization, whereas paraquat exposure perturbs fluxes associated with dopamine and its breakdown metabolites. The statistical results of the Monte-Carlo analysis suggest several specific mechanisms. The findings are interesting, because no a priori assumptions are made regarding specific pesticide actions, and all parameters characterizing the processes in the dopamine model are treated in an unbiased manner. Our results show how approaches from computational systems biology can help identify mechanisms underlying the toxicity of pesticide exposure. PMID:24269752

  12. A Dopamine Hypothesis of Autism Spectrum Disorder.

    PubMed

    Pavăl, Denis

    2017-01-01

    Autism spectrum disorder (ASD) comprises a group of neurodevelopmental disorders characterized by social deficits and stereotyped behaviors. While several theories have emerged, the pathogenesis of ASD remains unknown. Although studies report dopamine signaling abnormalities in autistic patients, a coherent dopamine hypothesis which could link neurobiology to behavior in ASD is currently lacking. In this paper, we present such a hypothesis by proposing that autistic behavior arises from dysfunctions in the midbrain dopaminergic system. We hypothesize that a dysfunction of the mesocorticolimbic circuit leads to social deficits, while a dysfunction of the nigrostriatal circuit leads to stereotyped behaviors. Furthermore, we discuss 2 key predictions of our hypothesis, with emphasis on clinical and therapeutic aspects. First, we argue that dopaminergic dysfunctions in the same circuits should associate with autistic-like behavior in nonautistic subjects. Concerning this, we discuss the case of PANDAS (pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections) which displays behaviors similar to those of ASD, presumed to arise from dopaminergic dysfunctions. Second, we argue that providing dopamine modulators to autistic subjects should lead to a behavioral improvement. Regarding this, we present clinical studies of dopamine antagonists which seem to have improving effects on autistic behavior. Furthermore, we explore the means of testing our hypothesis by using neuroreceptor imaging, which could provide comprehensive evidence for dopamine signaling dysfunctions in autistic subjects. Lastly, we discuss the limitations of our hypothesis. Along these lines, we aim to provide a dopaminergic model of ASD which might lead to a better understanding of the ASD pathogenesis. © 2017 S. Karger AG, Basel.

  13. Trans-blood brain barrier delivery of dopamine-loaded nanoparticles reverses functional deficits in parkinsonian rats.

    PubMed

    Pahuja, Richa; Seth, Kavita; Shukla, Anshi; Shukla, Rajendra Kumar; Bhatnagar, Priyanka; Chauhan, Lalit Kumar Singh; Saxena, Prem Narain; Arun, Jharna; Chaudhari, Bhushan Pradosh; Patel, Devendra Kumar; Singh, Sheelendra Pratap; Shukla, Rakesh; Khanna, Vinay Kumar; Kumar, Pradeep; Chaturvedi, Rajnish Kumar; Gupta, Kailash Chand

    2015-05-26

    Sustained and safe delivery of dopamine across the blood brain barrier (BBB) is a major hurdle for successful therapy in Parkinson's disease (PD), a neurodegenerative disorder. Therefore, in the present study we designed neurotransmitter dopamine-loaded PLGA nanoparticles (DA NPs) to deliver dopamine to the brain. These nanoparticles slowly and constantly released dopamine, showed reduced clearance of dopamine in plasma, reduced quinone adduct formation, and decreased dopamine autoxidation. DA NPs were internalized in dopaminergic SH-SY5Y cells and dopaminergic neurons in the substantia nigra and striatum, regions affected in PD. Treatment with DA NPs did not cause reduction in cell viability and morphological deterioration in SH-SY5Y, as compared to bulk dopamine-treated cells, which showed reduced viability. Herein, we report that these NPs were able to cross the BBB and capillary endothelium in the striatum and substantia nigra in a 6-hydroxydopamine (6-OHDA)-induced rat model of PD. Systemic intravenous administration of DA NPs caused significantly increased levels of dopamine and its metabolites and reduced dopamine-D2 receptor supersensitivity in the striatum of parkinsonian rats. Further, DA NPs significantly recovered neurobehavioral abnormalities in 6-OHDA-induced parkinsonian rats. Dopamine delivered through NPs did not cause additional generation of ROS, dopaminergic neuron degeneration, and ultrastructural changes in the striatum and substantia nigra as compared to 6-OHDA-lesioned rats. Interestingly, dopamine delivery through nanoformulation neither caused alterations in the heart rate and blood pressure nor showed any abrupt pathological change in the brain and other peripheral organs. These results suggest that NPs delivered dopamine into the brain, reduced dopamine autoxidation-mediated toxicity, and ultimately reversed neurochemical and neurobehavioral deficits in parkinsonian rats.

  14. Dysregulation of D₂-mediated dopamine transmission in monkeys after chronic escalating methamphetamine exposure.

    PubMed

    Groman, Stephanie M; Lee, Buyean; Seu, Emanuele; James, Alex S; Feiler, Karen; Mandelkern, Mark A; London, Edythe D; Jentsch, J David

    2012-04-25

    Compulsive drug-seeking and drug-taking are important substance-abuse behaviors that have been linked to alterations in dopaminergic neurotransmission and to impaired inhibitory control. Evidence supports the notions that abnormal D₂ receptor-mediated dopamine transmission and inhibitory control may be heritable risk factors for addictions, and that they also reflect drug-induced neuroadaptations. To provide a mechanistic explanation for the drug-induced emergence of inhibitory-control deficits, this study examined how a chronic, escalating-dose regimen of methamphetamine administration affected dopaminergic neurochemistry and cognition in monkeys. Dopamine D₂-like receptor and dopamine transporter (DAT) availability and reversal-learning performance were measured before and after exposure to methamphetamine (or saline), and brain dopamine levels were assayed at the conclusion of the study. Exposure to methamphetamine reduced dopamine D₂-like receptor and DAT availability and produced transient, selective impairments in the reversal of a stimulus-outcome association. Furthermore, individual differences in the change in D₂-like receptor availability in the striatum were related to the change in response to positive feedback. These data provide evidence that chronic, escalating-dose methamphetamine administration alters the dopamine system in a manner similar to that observed in methamphetamine-dependent humans. They also implicate alterations in positive-feedback sensitivity associated with D₂-like receptor dysfunction as the mechanism by which inhibitory control deficits emerge in stimulant-dependent individuals. Finally, a significant degree of neurochemical and behavioral variation in response to methamphetamine was detected, indicating that individual differences affect the degree to which drugs of abuse alter these processes. Identification of these factors ultimately may assist in the development of individualized treatments for substance dependence.

  15. ADHD-associated dopamine transporter, latrophilin and neurofibromin share a dopamine-related locomotor signature in Drosophila

    PubMed Central

    van der Voet, M; Harich, B; Franke, B; Schenck, A

    2016-01-01

    Attention-deficit/hyperactivity disorder (ADHD) is a common, highly heritable neuropsychiatric disorder with hyperactivity as one of the hallmarks. Aberrant dopamine signaling is thought to be a major theme in ADHD, but how this relates to the vast majority of ADHD candidate genes is illusive. Here we report a Drosophila dopamine-related locomotor endophenotype that is shared by pan-neuronal knockdown of orthologs of the ADHD-associated genes Dopamine transporter (DAT1) and Latrophilin (LPHN3), and of a gene causing a monogenic disorder with frequent ADHD comorbidity: Neurofibromin (NF1). The locomotor signature was not found in control models and could be ameliorated by methylphenidate, validating its relevance to symptoms of the disorder. The Drosophila ADHD endophenotype can be further exploited in high throughput to characterize the growing number of candidate genes. It represents an equally useful outcome measure for testing chemical compounds to define novel treatment options. PMID:25962619

  16. Conformational ensemble of human α-synuclein physiological form predicted by molecular simulations.

    PubMed

    Rossetti, G; Musiani, F; Abad, E; Dibenedetto, D; Mouhib, H; Fernandez, C O; Carloni, P

    2016-02-17

    We perform here enhanced sampling simulations of N-terminally acetylated human α-synuclein, an intrinsically disordered protein involved in Parkinson's disease. The calculations, consistent with experiments, suggest that the post-translational modification leads to the formation of a transient amphipathic α-helix. The latter, absent in the non-physiological form, alters protein dynamics at the N-terminal and intramolecular interactions.

  17. Dopamine Gene Profiling to Predict Impulse Control and Effects of Dopamine Agonist Ropinirole.

    PubMed

    MacDonald, Hayley J; Stinear, Cathy M; Ren, April; Coxon, James P; Kao, Justin; Macdonald, Lorraine; Snow, Barry; Cramer, Steven C; Byblow, Winston D

    2016-07-01

    Dopamine agonists can impair inhibitory control and cause impulse control disorders for those with Parkinson disease (PD), although mechanistically this is not well understood. In this study, we hypothesized that the extent of such drug effects on impulse control is related to specific dopamine gene polymorphisms. This double-blind, placebo-controlled study aimed to examine the effect of single doses of 0.5 and 1.0 mg of the dopamine agonist ropinirole on impulse control in healthy adults of typical age for PD onset. Impulse control was measured by stop signal RT on a response inhibition task and by an index of impulsive decision-making on the Balloon Analogue Risk Task. A dopamine genetic risk score quantified basal dopamine neurotransmission from the influence of five genes: catechol-O-methyltransferase, dopamine transporter, and those encoding receptors D1, D2, and D3. With placebo, impulse control was better for the high versus low genetic risk score groups. Ropinirole modulated impulse control in a manner dependent on genetic risk score. For the lower score group, both doses improved response inhibition (decreased stop signal RT) whereas the lower dose reduced impulsiveness in decision-making. Conversely, the higher score group showed a trend for worsened response inhibition on the lower dose whereas both doses increased impulsiveness in decision-making. The implications of the present findings are that genotyping can be used to predict impulse control and whether it will improve or worsen with the administration of dopamine agonists.

  18. Running wheel exercise reduces α-synuclein aggregation and improves motor and cognitive function in a transgenic mouse model of Parkinson's disease

    PubMed Central

    Barkow, Jessica Cummiskey; Freed, Curt R.

    2017-01-01

    Exercise has been recommended to improve motor function in Parkinson patients, but its value in altering progression of disease is unknown. In this study, we examined the neuroprotective effects of running wheel exercise in mice. In adult wild-type mice, one week of running wheel activity led to significantly increased DJ-1 protein concentrations in muscle and plasma. In DJ-1 knockout mice, running wheel performance was much slower and Rotarod performance was reduced, suggesting that DJ-1 protein is required for normal motor activity. To see if exercise can prevent abnormal protein deposition and behavioral decline in transgenic animals expressing a mutant human form of α-synuclein in all neurons, we set up running wheels in the cages of pre-symptomatic animals at 12 months old. Activity was monitored for a 3-month period. After 3 months, motor and cognitive performance on the Rotarod and Morris Water Maze were significantly better in running animals compared to control transgenic animals with locked running wheels. Biochemical analysis revealed that running mice had significantly higher DJ-1, Hsp70 and BDNF concentrations and had significantly less α-synuclein aggregation in brain compared to control mice. By contrast, plasma concentrations of α-synuclein were significantly higher in exercising mice compared to control mice. Our results suggest that exercise may slow the progression of Parkinson’s disease by preventing abnormal protein aggregation in brain. PMID:29272304

  19. Effect of perinatal asphyxia and carbamazepine treatment on cortical dopamine and DOPAC levels.

    PubMed

    López-Pérez, Silvia J; Morales-Villagrán, Alberto; Medina-Ceja, Laura

    2015-02-13

    One of the most important manifestations of perinatal asphyxia is the occurrence of seizures, which are treated with antiepileptic drugs, such as carbamazepine. These early seizures, combined with pharmacological treatments, may influence the development of dopaminergic neurotransmission in the frontal cortex. This study aimed to determine the extracellular levels of dopamine and its main metabolite DOPAC in 30-day-old rats that had been asphyxiated for 45 min in a low (8%) oxygen chamber at a perinatal age and treated with daily doses of carbamazepine. Quantifications were performed using microdialysis coupled to a high-performance liquid chromatography (HPLC) system in basal conditions and following the use of the chemical stimulus. Significant decreases in basal and stimulated extracellular dopamine and DOPAC content were observed in the frontal cortex of the asphyxiated group, and these decreases were partially recovered in the animals administered daily doses of carbamazepine. Greater basal dopamine concentrations were also observed as an independent effect of carbamazepine. Perinatal asphyxia plus carbamazepine affects extracellular levels of dopamine and DOPAC in the frontal cortex and stimulated the release of dopamine, which provides evidence for the altered availability of dopamine in cortical brain areas during brain development.

  20. Curcumin Pyrazole and its derivative (N-(3-Nitrophenylpyrazole) Curcumin inhibit aggregation, disrupt fibrils and modulate toxicity of Wild type and Mutant α-Synuclein

    PubMed Central

    Ahsan, Nuzhat; Mishra, Satyendra; Jain, Manish Kumar; Surolia, Avadhesha; Gupta, Sarika

    2015-01-01

    Accumulating evidence suggests that deposition of neurotoxic α-synuclein aggregates in the brain during the development of neurodegenerative diseases like Parkinson’s disease can be curbed by anti-aggregation strategies that either disrupt or eliminate toxic aggregates. Curcumin, a dietary polyphenol exhibits anti-amyloid activity but the use of this polyphenol is limited owing to its instability. As chemical modifications in curcumin confiscate this limitation, such efforts are intensively performed to discover molecules with similar but enhanced stability and superior properties. This study focuses on the inhibitory effect of two stable analogs of curcumin viz. curcumin pyrazole and curcumin isoxazole and their derivatives against α-synuclein aggregation, fibrillization and toxicity. Employing biochemical, biophysical and cell based assays we discovered that curcumin pyrazole (3) and its derivative N-(3-Nitrophenylpyrazole) curcumin (15) exhibit remarkable potency in not only arresting fibrillization and disrupting preformed fibrils but also preventing formation of A11 conformation in the protein that imparts toxic effects. Compounds 3 and 15 also decreased neurotoxicity associated with fast aggregating A53T mutant form of α-synuclein. These two analogues of curcumin described here may therefore be useful therapeutic inhibitors for the treatment of α-synuclein amyloidosis and toxicity in Parkinson’s disease and other synucleinopathies. PMID:25985292

  1. Dopamine depresses excitatory synaptic transmission onto rat subicular neurons via presynaptic D1-like dopamine receptors.

    PubMed

    Behr, J; Gloveli, T; Schmitz, D; Heinemann, U

    2000-07-01

    Schizophrenia is considered to be associated with an abnormal functioning of the hippocampal output. The high clinical potency of antipsychotics that act as antagonists at dopamine (DA) receptors indicate a hyperfunction of the dopaminergic system. The subiculum obtains information from area CA1 and the entorhinal cortex and represents the major output region of the hippocampal complex. To clarify whether an enhanced dopaminergic activity alters the hippocampal output, the effect of DA on alveus- and perforant path-evoked excitatory postsynaptic currents (EPSCs) in subicular neurons was examined using conventional intracellular and whole cell voltage-clamp recordings. Dopamine (100 microM) depressed alveus-elicited (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated EPSCs to 56 +/- 8% of control while perforant path-evoked EPSCs were attenuated to only 76 +/- 7% of control. Dopamine had no effect on the EPSC kinetics. Dopamine reduced the frequency of spontaneous miniature EPSCs without affecting their amplitudes. The sensitivity of subicular neurons to the glutamate receptor agonist (S)-alpha-amino-3-hydoxy-5-methyl-4-isoxazolepropionic acid was unchanged by DA pretreatment, excluding a postsynaptic mechanism for the observed reduction of excitatory synaptic transmission. The effect of DA on evoked EPSCs was mimicked by the D1 receptor agonist SFK 38393 and partially antagonized by the D1 receptor antagonist SCH 23390. While the D2 receptor agonist quinelorane failed to reduce the EPSCs, the D2 receptor antagonist sulpiride did not block the action of DA. The results indicate that DA strongly depresses the hippocampal and the entorhinal excitatory input onto subicular neurons by decreasing the glutamate release following activation of presynaptic D1-like DA receptors.

  2. Sleep Deprivation Decreases [11C]Raclopride’s Binding to Dopamine D2/D3 Receptors in the Human Brain

    PubMed Central

    Volkow, Nora D.; Wang, Gene-Jack; Telang, Frank; Fowler, Joanna S.; Logan, Jean; Wong, Christopher; Ma, Jim; Pradhan, Kith; Tomasi, Dardo; Thanos, Peter K.; Ferré, Sergi; Jayne, Millard

    2009-01-01

    Sleep deprivation can markedly impair human performance contributing to accidents and poor productivity. The mechanisms underlying this impairment are not well understood but brain dopamine systems have been implicated. Here we test whether one night of sleep deprivation changes dopamine brain activity. We studied fifteen healthy subjects using positron emission tomography and [11C]raclopride (dopamine D2/3 receptor radioligand) and [11C]cocaine (dopamine transporter radioligand). Subjects were tested twice; after one night of rested sleep and after on night of sleep deprivation. [11C]Raclopride’s specific binding in striatum and thalamus were significantly reduced after sleep deprivation and the magnitude of this reduction correlated with increases in fatigue (tiredness and sleepiness) and with deterioration in cognitive performance (visual attention and working memory). In contrast sleep deprivation did not affect the specific binding of [11C]cocaine in striatum. Since [11C]raclopride competes with endogenous dopamine for binding to D2/D3 receptors, we interpret the decreases in binding to reflect dopamine increases with sleep deprivation. However, we can not rule out the possibility that decreased [11C]raclopride binding reflects decreases in receptor levels or affinity. Sleep deprivation did not affect dopamine transporters (target for most wake-promoting medications) and thus dopamine increases are likely to reflect increases in dopamine cell firing and/or release rather than decreases in dopamine reuptake. Inasmuch as dopamine-enhancing drugs increase wakefulness we postulate that dopamine increases after sleep deprivation is a mechanism by which the brain maintains arousal as the drive to sleep increases but one that is insufficient to counteract behavioral and cognitive impairment. PMID:18716203

  3. Serotonin 2B Receptors in Mesoaccumbens Dopamine Pathway Regulate Cocaine Responses.

    PubMed

    Doly, Stéphane; Quentin, Emily; Eddine, Raphaël; Tolu, Stefania; Fernandez, Sebastian P; Bertran-Gonzalez, Jesus; Valjent, Emmanuel; Belmer, Arnauld; Viñals, Xavier; Callebert, Jacques; Faure, Philippe; Meye, Frank J; Hervé, Denis; Robledo, Patricia; Mameli, Manuel; Launay, Jean-Marie; Maldonado, Rafael; Maroteaux, Luc

    2017-10-25

    Addiction is a maladaptive pattern of behavior following repeated use of reinforcing drugs in predisposed individuals, leading to lifelong changes. Common among these changes are alterations of neurons releasing dopamine in the ventral and dorsal territories of the striatum. The serotonin 5-HT 2B receptor has been involved in various behaviors, including impulsivity, response to antidepressants, and response to psychostimulants, pointing toward putative interactions with the dopamine system. Despite these findings, it remains unknown whether 5-HT 2B receptors directly modulate dopaminergic activity and the possible mechanisms involved. To answer these questions, we investigated the contribution of 5-HT 2B receptors to cocaine-dependent behavioral responses. Male mice permanently lacking 5-HT 2B receptors, even restricted to dopamine neurons, developed heightened cocaine-induced locomotor responses. Retrograde tracing combined with single-cell mRNA amplification indicated that 5-HT 2B receptors are expressed by mesolimbic dopamine neurons. In vivo and ex vivo electrophysiological recordings showed that 5-HT 2B -receptor inactivation in dopamine neurons affects their neuronal activity and increases AMPA-mediated over NMDA-mediated excitatory synaptic currents. These changes are associated with lower ventral striatum dopamine activity and blunted cocaine self-administration. These data identify the 5-HT 2B receptor as a pharmacological intermediate and provide mechanistic insight into attenuated dopamine tone following exposure to drugs of abuse. SIGNIFICANCE STATEMENT Here we report that mice lacking 5-HT 2B receptors totally or exclusively in dopamine neurons exhibit heightened cocaine-induced locomotor responses. Despite the sensitized state of these mice, we found that associated changes include lower ventral striatum dopamine activity and lower cocaine operant self-administration. We described the selective expression of 5-HT 2B receptors in a subpopulation of

  4. Dopamine receptors – IUPHAR Review 13

    PubMed Central

    Beaulieu, Jean-Martin; Espinoza, Stefano; Gainetdinov, Raul R

    2015-01-01

    The variety of physiological functions controlled by dopamine in the brain and periphery is mediated by the D1, D2, D3, D4 and D5 dopamine GPCRs. Drugs acting on dopamine receptors are significant tools for the management of several neuropsychiatric disorders including schizophrenia, bipolar disorder, depression and Parkinson's disease. Recent investigations of dopamine receptor signalling have shown that dopamine receptors, apart from their canonical action on cAMP-mediated signalling, can regulate a myriad of cellular responses to fine-tune the expression of dopamine-associated behaviours and functions. Such signalling mechanisms may involve alternate G protein coupling or non-G protein mechanisms involving ion channels, receptor tyrosine kinases or proteins such as β-arrestins that are classically involved in GPCR desensitization. Another level of complexity is the growing appreciation of the physiological roles played by dopamine receptor heteromers. Applications of new in vivo techniques have significantly furthered the understanding of the physiological functions played by dopamine receptors. Here we provide an update of the current knowledge regarding the complex biology, signalling, physiology and pharmacology of dopamine receptors. PMID:25671228

  5. Effect of Dopamine Therapy on Nonverbal Affect Burst Recognition in Parkinson's Disease

    PubMed Central

    Péron, Julie; Grandjean, Didier; Drapier, Sophie; Vérin, Marc

    2014-01-01

    Background Parkinson's disease (PD) provides a model for investigating the involvement of the basal ganglia and mesolimbic dopaminergic system in the recognition of emotions from voices (i.e., emotional prosody). Although previous studies of emotional prosody recognition in PD have reported evidence of impairment, none of them compared PD patients at different stages of the disease, or ON and OFF dopamine replacement therapy, making it difficult to determine whether their impairment was due to general cognitive deterioration or to a more specific dopaminergic deficit. Methods We explored the involvement of the dopaminergic pathways in the recognition of nonverbal affect bursts (onomatopoeias) in 15 newly diagnosed PD patients in the early stages of the disease, 15 PD patients in the advanced stages of the disease and 15 healthy controls. The early PD group was studied in two conditions: ON and OFF dopaminergic therapy. Results Results showed that the early PD patients performed more poorly in the ON condition than in the OFF one, for overall emotion recognition, as well as for the recognition of anger, disgust and fear. Additionally, for anger, the early PD ON patients performed more poorly than controls. For overall emotion recognition, both advanced PD patients and early PD ON patients performed more poorly than controls. Analysis of continuous ratings on target and nontarget visual analog scales confirmed these patterns of results, showing a systematic emotional bias in both the advanced PD and early PD ON (but not OFF) patients compared with controls. Conclusions These results i) confirm the involvement of the dopaminergic pathways and basal ganglia in emotional prosody recognition, and ii) suggest a possibly deleterious effect of dopatherapy on affective abilities in the early stages of PD. PMID:24651759

  6. Model-based predictions for dopamine.

    PubMed

    Langdon, Angela J; Sharpe, Melissa J; Schoenbaum, Geoffrey; Niv, Yael

    2018-04-01

    Phasic dopamine responses are thought to encode a prediction-error signal consistent with model-free reinforcement learning theories. However, a number of recent findings highlight the influence of model-based computations on dopamine responses, and suggest that dopamine prediction errors reflect more dimensions of an expected outcome than scalar reward value. Here, we review a selection of these recent results and discuss the implications and complications of model-based predictions for computational theories of dopamine and learning. Copyright © 2017. Published by Elsevier Ltd.

  7. Mutant LRRK2 Toxicity in Neurons Depends on LRRK2 Levels and Synuclein But Not Kinase Activity or Inclusion Bodies

    PubMed Central

    Skibinski, Gaia; Nakamura, Ken; Cookson, Mark R.

    2014-01-01

    By combining experimental neuron models and mathematical tools, we developed a “systems” approach to deconvolve cellular mechanisms of neurodegeneration underlying the most common known cause of Parkinson's disease (PD), mutations in leucine-rich repeat kinase 2 (LRRK2). Neurons ectopically expressing mutant LRRK2 formed inclusion bodies (IBs), retracted neurites, accumulated synuclein, and died prematurely, recapitulating key features of PD. Degeneration was predicted from the levels of diffuse mutant LRRK2 that each neuron contained, but IB formation was neither necessary nor sufficient for death. Genetic or pharmacological blockade of its kinase activity destabilized LRRK2 and lowered its levels enough to account for the moderate reduction in LRRK2 toxicity that ensued. By contrast, targeting synuclein, including neurons made from PD patient-derived induced pluripotent cells, dramatically reduced LRRK2-dependent neurodegeneration and LRRK2 levels. These findings suggest that LRRK2 levels are more important than kinase activity per se in predicting toxicity and implicate synuclein as a major mediator of LRRK2-induced neurodegeneration. PMID:24403142

  8. Pharmacological Chaperones of the Dopamine Transporter Rescue Dopamine Transporter Deficiency Syndrome Mutations in Heterologous Cells*

    PubMed Central

    Lam, Vincent M.; Salahpour, Ali

    2016-01-01

    A number of pathological conditions have been linked to mutations in the dopamine transporter gene, including hereditary dopamine transporter deficiency syndrome (DTDS). DTDS is a rare condition that is caused by autosomal recessive loss-of-function mutations in the dopamine transporter (DAT), which often affects transporter trafficking and folding. We examined the possibility of using pharmacological chaperones of DAT to rescue DTDS mutations. After screening a set of known DAT ligands for their ability to increase DAT surface expression, we found that bupropion and ibogaine increased DAT surface expression, whereas others, including cocaine and methylphenidate, had no effect. Bupropion and ibogaine increased wild type DAT protein levels and also promoted maturation of the endoplasmic reticulum (ER)-retained DAT mutant K590A. Rescue of K590A could be blocked by inhibiting ER to Golgi transport using brefeldin A. Furthermore, knockdown of coat protein complex II (COPII) component SEC24D, which is important in the ER export of wild type DAT, also blocked the rescue effects of bupropion and ibogaine. These data suggest that bupropion and ibogaine promote maturation of DAT by acting as pharmacological chaperones in the ER. Importantly, both drugs rescue DAT maturation and functional activity of the DTDS-associated mutations A314V and R445C. Together, these results are the first demonstration of pharmacological chaperoning of DAT and suggest this may be a viable approach to increase DAT levels in DTDS and other conditions associated with reduced DAT function. PMID:27555326

  9. Dopamine and extinction: A convergence of theory with fear and reward circuitry

    PubMed Central

    Abraham, Antony D.; Neve, Kim A.; Lattal, K. Matthew

    2014-01-01

    Research on dopamine lies at the intersection of sophisticated theoretical and neurobiological approaches to learning and memory. Dopamine has been shown to be critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine’s function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in reward-related tasks. A parallel and growing literature indicates that dopamine is involved in fear conditioning and extinction. These studies are consistent with long-standing ideas about appetitive-aversive interactions in learning theory and they speak to the general nature of cellular and molecular processes that underlie behavior. We review the behavioral and neurobiological literature showing a role for dopamine in fear conditioning and extinction. At a cellular level, we review dopamine signaling and receptor pharmacology, cellular and molecular events that follow dopamine receptor activation, and brain systems in which dopamine functions. At a behavioral level, we describe theories of learning and dopamine function that could describe the fundamental rules underlying how dopamine modulates different aspects of learning and memory processes. PMID:24269353

  10. Mesolimbic Dopamine Signals the Value of Work

    PubMed Central

    Hamid, Arif A.; Pettibone, Jeffrey R.; Mabrouk, Omar S.; Hetrick, Vaughn L.; Schmidt, Robert; Vander Weele, Caitlin M.; Kennedy, Robert T.; Aragona, Brandon J.; Berke, Joshua D.

    2015-01-01

    Dopamine cell firing can encode errors in reward prediction, providing a learning signal to guide future behavior. Yet dopamine is also a key modulator of motivation, invigorating current behavior. Existing theories propose that fast (“phasic”) dopamine fluctuations support learning, while much slower (“tonic”) dopamine changes are involved in motivation. We examined dopamine release in the nucleus accumbens across multiple time scales, using complementary microdialysis and voltammetric methods during adaptive decision-making. We first show that minute-by-minute dopamine levels covary with reward rate and motivational vigor. We then show that second-by-second dopamine release encodes an estimate of temporally-discounted future reward (a value function). We demonstrate that changing dopamine immediately alters willingness to work, and reinforces preceding action choices by encoding temporal-difference reward prediction errors. Our results indicate that dopamine conveys a single, rapidly-evolving decision variable, the available reward for investment of effort, that is employed for both learning and motivational functions. PMID:26595651

  11. Effect of beta-phenylethylamine on extracellular concentrations of dopamine in the nucleus accumbens and prefrontal cortex.

    PubMed

    Murata, Mikio; Katagiri, Nobuyuki; Ishida, Kota; Abe, Kenji; Ishikawa, Masago; Utsunomiya, Iku; Hoshi, Keiko; Miyamoto, Ken-ichi; Taguchi, Kyoji

    2009-05-07

    It is known that psychostimulants stimulate dopamine transmission in the nucleus accumbens. In the present study, we examined the effects of systemically administered beta-phenylethylamine (beta-PEA), a psychomotor-stimulating trace amine, on dopamine concentrations in the nucleus accumbens and prefrontal cortex in freely moving rats, using an in vivo microdialysis technique. Intraperitoneal administration of beta-PEA (12.5 and 25 mg/kg) significantly increased extracellular dopamine levels in the nucleus accumbens shell. The observed increase in the dopamine concentration in nucleus accumbens shell dialysate after intraperitoneal administration of 25 mg/kg beta-PEA was inhibited by pre-treatment with a dopamine uptake inhibitor, GBR12909 (10 mg/kg, i.p.). In contrast, beta-PEA (25 mg/kg, i.p.) did not affect dopamine release in the nucleus accumbens core. Although a high dose of beta-PEA (50 mg/kg) significantly increased dopamine levels in the nucleus accumbens core, the dopamine increasing effect of beta-PEA was more potent in the nucleus accumbens shell. Systemic administration of 12.5 and 25 mg/kg beta-PEA also increased extracellular dopamine levels in the prefrontal cortex of rats. However, systemic 25 mg/kg beta-PEA-induced increases in extracellular dopamine levels were not blocked by GBR12909 within the prefrontal cortex. These results suggest that beta-PEA has a greater effect in the shell than in the core and low-dose beta-PEA stimulates dopamine release in the nucleus accumbens shell through uptake by a dopamine transporter. Similarly, beta-PEA increased extracellular dopamine levels in the prefrontal cortex. Thus, beta-PEA may increase extracellular dopamine concentrations in the mesocorticolimbic pathway.

  12. Olfactory discrimination deficits in mice lacking the dopamine transporter or the D2 dopamine receptor.

    PubMed

    Tillerson, Jennifer L; Caudle, W Michael; Parent, Jack M; Gong, C; Schallert, Timothy; Miller, Gary W

    2006-09-15

    Previous pharmacological studies have implicated dopamine as a modulator of olfactory bulb processing. Several disorders characterized by altered dopamine homeostasis in olfaction-related brain regions display olfactory deficits. To further characterize the role of dopamine in olfactory processing, we subjected dopamine transporter knockout mice (DAT -/-) and dopamine receptor 2 knockout mice (D2 -/-) to a battery of olfactory tests. In addition to behavioral characterization, several neurochemical markers of olfactory bulb integrity and function were examined. DAT -/- mice displayed an olfactory discrimination deficit, but did not differ detectably from DAT wildtype (DAT +/+) mice in odor habituation, olfactory sensitivity, or odor recognition memory. Neurochemically, DAT -/- mice have decreased D2 receptor staining in the periglomerular layer of the olfactory bulb and increased tyrosine hydroxylase immunoreactivity compared to DAT +/+ controls. D2 -/- mice exhibited the same olfactory deficit as the DAT -/- mice, further supporting the role of dopamine at the D2 synapse in olfactory discrimination processing. The findings presented in this paper reinforce the functional significance of dopamine and more specifically the D2 receptor in olfactory discrimination and may help explain the behavioral phenotype in the DAT and D2 knockout mice.

  13. Down-regulation of natural resistance-associated macrophage protein-1 (Nramp1) is associated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)/1-methyl-4-phenylpyridinium (MPP+ )-induced α-synuclein accumulation and neurotoxicity.

    PubMed

    Wu, K-C; Liou, H-H; Lee, C-Y; Lin, C-J

    2018-04-21

    The accumulation of α-synuclein is a hallmark in the pathogenesis of Parkinson's disease (PD). Natural resistance-associated macrophage protein-1 (Nramp1) was previously shown to contribute to the degradation of extracellular α-synuclein in microglia under conditions of iron overload. This study was aimed at investigating the role of Nramp1 in α-synuclein pathology in the neurone under 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)/1-methyl-4-phenylpyridinium (MPP + ) treatment. The expression of Nramp1 and pathological features (including iron and α-synuclein accumulation) were examined in the dopaminergic neurones of humans (with and without PD) and of mice [with and without receiving chronic MPTP intoxication]. The effects of Nramp1 expression on low-dose MPP + -induced α-synuclein expression and neurotoxicity were determined in human dopaminergic neuroblastoma SH-SY5Y cells. Similar to the findings in the substantia nigra of human PD, lower expression of Nramp1 but higher levels of iron and α-synuclein were identified in the dopaminergic neurones of mice receiving chronic MPTP intoxication, compared to controls. In parallel to the loss of dopaminergic neurones, the numbers of glial fibrillary acidic protein- and ionized calcium-binding adapter molecule-1-positive cells were significantly increased in the substantia nigra of MPTP-treated mice. Likewise, in human neuroblastoma SH-SY5Y cells exposed to low-dose MPP + , Nramp1 expression and cathepsin D activity were decreased, along with an increase in α-synuclein protein expression and aggregation. Overexpression of functional Nramp1 restored cathepsin D activity and attenuated α-synuclein up-regulation and neuronal cell death caused by MPP + treatment. These data suggest that the neuronal expression of Nramp1 is important for protecting against the development of MPTP/MPP + -induced α-synuclein pathology and neurotoxicity. © 2018 British Neuropathological Society.

  14. Effects of Dopamine Medication on Sequence Learning with Stochastic Feedback in Parkinson's Disease

    PubMed Central

    Seo, Moonsang; Beigi, Mazda; Jahanshahi, Marjan; Averbeck, Bruno B.

    2010-01-01

    A growing body of evidence suggests that the midbrain dopamine system plays a key role in reinforcement learning and disruption of the midbrain dopamine system in Parkinson's disease (PD) may lead to deficits on tasks that require learning from feedback. We examined how changes in dopamine levels (“ON” and “OFF” their dopamine medication) affect sequence learning from stochastic positive and negative feedback using Bayesian reinforcement learning models. We found deficits in sequence learning in patients with PD when they were “ON” and “OFF” medication relative to healthy controls, but smaller differences between patients “OFF” and “ON”. The deficits were mainly due to decreased learning from positive feedback, although across all participant groups learning was more strongly associated with positive than negative feedback in our task. The learning in our task is likely mediated by the relatively depleted dorsal striatum and not the relatively intact ventral striatum. Therefore, the changes we see in our task may be due to a strong loss of phasic dopamine signals in the dorsal striatum in PD. PMID:20740077

  15. Striatal dopamine in Parkinson disease: A meta-analysis of imaging studies.

    PubMed

    Kaasinen, Valtteri; Vahlberg, Tero

    2017-12-01

    A meta-analysis of 142 positron emission tomography and single photon emission computed tomography studies that have investigated striatal presynaptic dopamine function in Parkinson disease (PD) was performed. Subregional estimates of striatal dopamine metabolism are presented. The aromatic L-amino-acid decarboxylase (AADC) defect appears to be consistently smaller than the dopamine transporter and vesicular monoamine transporter 2 defects, suggesting upregulation of AADC function in PD. The correlation between disease severity and dopamine loss appears linear, but the majority of longitudinal studies point to a negative exponential progression pattern of dopamine loss in PD. Ann Neurol 2017;82:873-882. © 2017 American Neurological Association.

  16. Visualizing dopamine released from living cells using a nanoplasmonic probe

    NASA Astrophysics Data System (ADS)

    Qin, W. W.; Wang, S. P.; Li, J.; Peng, T. H.; Xu, Y.; Wang, K.; Shi, J. Y.; Fan, C. H.; Li, D.

    2015-09-01

    We report the development of an ultrasensitive nanoplasmonic probe for discriminative detection and imaging of dopamine released from living cells. The sensing mechanism is based on the dopamine-induced seeded-growth of Au nanoparticles (Au NPs) that leads to the shift of the plasmon band. This platform allows for the detection of dopamine with a detection limit down to 0.25 pM within 1 min. This nanoplasmonic assay is further applied to visualize the release of dopamine from living rat pheochromocytoma (PC12) cells under ATP-stimulation with dark-field microscopy (DFM). The DFM results together with real time fluorescence imaging of PC12 cells stained with the Fluo calcium indicator, suggested that ATP stimulated-release of dopamine is concomitant with the Ca2+ influx, and the influx of Ca2+ is through ATP-activated channels instead of the voltage-gated Ca2+ channel (VGC).We report the development of an ultrasensitive nanoplasmonic probe for discriminative detection and imaging of dopamine released from living cells. The sensing mechanism is based on the dopamine-induced seeded-growth of Au nanoparticles (Au NPs) that leads to the shift of the plasmon band. This platform allows for the detection of dopamine with a detection limit down to 0.25 pM within 1 min. This nanoplasmonic assay is further applied to visualize the release of dopamine from living rat pheochromocytoma (PC12) cells under ATP-stimulation with dark-field microscopy (DFM). The DFM results together with real time fluorescence imaging of PC12 cells stained with the Fluo calcium indicator, suggested that ATP stimulated-release of dopamine is concomitant with the Ca2+ influx, and the influx of Ca2+ is through ATP-activated channels instead of the voltage-gated Ca2+ channel (VGC). Electronic supplementary information (ESI) available: Fig. S1-S4 and Table S1. See DOI: 10.1039/c5nr04433b

  17. Glucocorticoid receptors in the prefrontal cortex regulate stress-evoked dopamine efflux and aspects of executive function.

    PubMed

    Butts, Kelly A; Weinberg, Joanne; Young, Allan H; Phillips, Anthony G

    2011-11-08

    Enhanced dopamine efflux in the prefrontal cortex is a well-documented response to acute stress. However, the underlying mechanism(s) for this response is unknown. Using in vivo microdialysis, we demonstrate that blocking glucocorticoid receptors locally within the rat prefrontal cortex results in a reduction in stress-evoked dopamine efflux. In contrast, blocking glucocorticoid receptors in the ventral tegmental area did not affect stress-evoked dopamine efflux in the prefrontal cortex. Additionally, local administration of corticosterone into the prefrontal cortex increased prefrontal dopamine efflux. The functional impact of enhanced dopamine efflux evoked by acute stress was demonstrated using a cognitive task dependent on the prefrontal cortex and sensitive to impairment in working memory. Notably, stress-induced impairments in cognition were attenuated by blockade of glucocorticoid receptors in the prefrontal cortex. Taken together, these data demonstrate that glucocorticoids act locally within the prefrontal cortex to modulate mesocortical dopamine efflux leading to the cognitive impairments observed during acute stress.

  18. Using Gastrocnemius sEMG and Plasma α-Synuclein for the Prediction of Freezing of Gait in Parkinson's Disease Patients

    PubMed Central

    Yang, Qiong; Zhang, Lin-Yuan; Chen, Sheng-Di; Liu, Jun

    2014-01-01

    Freezing of gait (FOG) is a complicated gait disturbance in Parkinson's disease (PD) and a relevant subclinical predictor algorithm is lacking. The main purpose of this study is to explore the potential value of surface electromyograph (sEMG) and plasma α-synuclein levels as predictors of the FOG seen in PD. 21 PD patients and 15 normal controls were recruited. Motor function was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) and Freezing of gait questionnaire (FOG-Q). Simultaneously, gait analysis was also performed using VICON capture system in PD patients and sEMG data was recorded as well. Total plasma α-synuclein was quantitatively assessed by Luminex assay in all participants. Recruited PD patients were classified into two groups: PD patients with FOG (PD+FOG) and without FOG (PD-FOG), based on clinical manifestation, the results of the FOG-Q and VICON capture system. PD+FOG patients displayed higher FOG-Q scores, decreased walking speed, smaller step length, smaller stride length and prolonged double support time compared to the PD-FOG in the gait trial. sEMG data indicated that gastrocnemius activity in PD+FOG patients was significantly reduced compared to PD-FOG patients. In addition, plasma α-synuclein levels were significantly decreased in the PD+FOG group compared to control group; however, no significant difference was found between the PD+FOG and PD-FOG groups. Our study revealed that gastrocnemius sEMG could be used to evaluate freezing gait in PD patients, while plasma α-synuclein might discriminate freezing of gait in PD patients from normal control, though no difference was found between the PD+FOG and PD-FOG groups. PMID:24586710

  19. Structural and Functional Effect of an Oscillating Electric Field on the Dopamine-D3 Receptor: A Molecular Dynamics Simulation Study

    PubMed Central

    Fallah, Zohreh; Jamali, Yousef; Rafii-Tabar, Hashem

    2016-01-01

    Dopamine as a neurotransmitter plays a critical role in the functioning of the central nervous system. The structure of D3 receptor as a member of class A G-protein coupled receptors (GPCRs) has been reported. We used MD simulation to investigate the effect of an oscillating electric field, with frequencies in the range 0.6–800 GHz applied along the z-direction, on the dopamine-D3R complex. The simulations showed that at some frequencies, the application of an external oscillating electric field along the z-direction has a considerable effect on the dopamine-D3R. However, there is no enough evidence for prediction of changes in specific frequency, implying that there is no order in changes. Computing the correlation coefficient parameter showed that increasing the field frequency can weaken the interaction between dopamine and D3R and may decrease the Arg128{3.50}-Glu324{6.30} distance. Because of high stability of α helices along the z-direction, applying an oscillating electric field in this direction with an amplitude 10-time higher did not have a considerable effect. However, applying the oscillating field at the frequency of 0.6 GHz along other directions, such as X-Y and Y-Z planes, could change the energy between the dopamine and the D3R, and the number of internal hydrogen bonds of the protein. This can be due to the effect of the direction of the electric field vis-à-vis the ligands orientation and the interaction of the oscillating electric field with the dipole moment of the protein. PMID:27832207

  20. Intracellular soluble α‐synuclein oligomers reduce pyramidal cell excitability

    PubMed Central

    Kaufmann, Timothy J.; Harrison, Paul M.; Richardson, Magnus J. E.; Pinheiro, Teresa J. T.

    2016-01-01

    Key points The presynaptic protein α‐synuclein forms aggregates during Parkinson's disease.Accumulating evidence suggests that the small soluble oligomers of α‐synuclein are more toxic than the larger aggregates appearing later in the disease.The link between oligomer toxicity and structure still remains unclear.In the present study, we have produced two structurally‐defined oligomers that have a similar morphology but differ in secondary structure.These oligomers were introduced into neocortical pyramidal cells during whole‐cell recording and, using a combination of experimentation and modelling, electrophysiological parameters were extracted.Both oligomeric species had similar effects on neuronal properties reducing input resistance, time constant and increasing capacitance. The net effect was a marked reduction in neuronal excitability that could impact on network activity. Abstract The presynaptic protein α‐synuclein (αSyn) aggregates during Parkinson's disease (PD) to form large proteinaceous amyloid plaques, the spread of which throughout the brain clinically defines the severity of the disease. During early stages of aggregation, αSyn forms soluble annular oligomers that show greater toxicity than much larger fibrils. These oligomers produce toxicity via a number of possible mechanisms, including the production of pore‐forming complexes that permeabilize membranes. In the present study, two well‐defined species of soluble αSyn oligomers were produced by different protocols: by polymerization of monomer and by sonication of fibrils. The two oligomeric species produced were morphologically similar, with both having an annular structure and consisting of approximately the same number of monomer subunits, although they differed in their secondary structure. Oligomeric and monomeric αSyn were injected directly into the soma of pyramidal neurons in mouse neocortical brain slices during whole‐cell patch clamp recording. Using a combined

  1. Putting desire on a budget: dopamine and energy expenditure, reconciling reward and resources

    PubMed Central

    Beeler, Jeff A.; Frazier, Cristianne R. M.; Zhuang, Xiaoxi

    2012-01-01

    Accumulating evidence indicates integration of dopamine function with metabolic signals, highlighting a potential role for dopamine in energy balance, frequently construed as modulating reward in response to homeostatic state. Though its precise role remains controversial, the reward perspective of dopamine has dominated investigation of motivational disorders, including obesity. In the hypothesis outlined here, we suggest instead that the primary role of dopamine in behavior is to modulate activity to adapt behavioral energy expenditure to the prevailing environmental energy conditions, with the role of dopamine in reward and motivated behaviors derived from its primary role in energy balance. Dopamine has long been known to modulate activity, exemplified by psychostimulants that act via dopamine. More recently, there has been nascent investigation into the role of dopamine in modulating voluntary activity, with some investigators suggesting that dopamine may serve as a final common pathway that couples energy sensing to regulated voluntary energy expenditure. We suggest that interposed between input from both the internal and external world, dopamine modulates behavioral energy expenditure along two axes: a conserve-expend axis that regulates generalized activity and an explore-exploit axes that regulates the degree to which reward value biases the distribution of activity. In this view, increased dopamine does not promote consumption of tasty food. Instead increased dopamine promotes energy expenditure and exploration while decreased dopamine favors energy conservation and exploitation. This hypothesis provides a mechanistic interpretation to an apparent paradox: the well-established role of dopamine in food seeking and the findings that low dopaminergic functions are associated with obesity. Our hypothesis provides an alternative perspective on the role of dopamine in obesity and reinterprets the “reward deficiency hypothesis” as a perceived energy deficit

  2. Dysregulation of D2-Mediated Dopamine Transmission in Monkeys after Chronic Escalating Methamphetamine Exposure

    PubMed Central

    Groman, S.M.; Lee, B.; Seu, E.; James, A.S.; Feiler, K.; Mandelkern, M.A.; London, E.D.; Jentsch, J.D.

    2012-01-01

    Compulsive drug-seeking and drug-taking are important substance-abuse behaviors that have been linked to alterations in dopaminergic neurotransmission and to impaired inhibitory control. Evidence supports the notions that abnormal D2 receptor-mediated dopamine transmission and inhibitory control may be heritable risk factors for addictions, and that they also reflect drug-induced neuroadaptations. To provide a mechanistic explanation for the drug-induced emergence of inhibitory-control deficits, this study examined how a chronic, escalating-dose regimen of methamphetamine administration affected dopaminergic neurochemistry and cognition in monkeys. Dopamine D2-like receptor and dopamine transporter (DAT) availability and reversal-learning performance were measured before and after exposure to methamphetamine (or saline), and brain dopamine levels were assayed at the conclusion of the study. Exposure to methamphetamine reduced dopamine D2-like receptor and DAT availability, and produced transient, selective impairments in the reversal of a stimulus-outcome association. Furthermore, individual differences in the change in D2-like receptor availability in the striatum were related to the change in response to positive feedback. These data provide evidence that chronic, escalating-dose methamphetamine administration alters the dopamine system in a manner similar to that observed in methamphetamine-dependent humans. They also implicate alterations in positive-feedback sensitivity associated with D2-like receptor dysfunction as the mechanism by which inhibitory control deficits emerge in stimulant-dependent individuals. Finally, a significant degree of neurochemical and behavioral variation in response to methamphetamine was detected, indicating that individual differences affect the degree to which drugs of abuse alter these processes. Identification of these factors ultimately may assist in the development of individualized treatments for substance dependence. PMID

  3. Further evidence of no linkage between schizophrenia and the dopamine D{sub 3} receptor gene locus

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nanko, S.; Fukuda, R.; Hattori, M.

    The dopamine hypothesis of schizophrenia proposed that dopaminergic pathways are involved in the etiology of the disease. In particular, interest among psychiatrists has focused on the D{sub 2} receptor because of its affinity to antipsychotic drugs. Recently a new dopamine receptor gene has been cloned and named the dopamine D{sub 3} receptor. The D{sub 3} receptor is a potential site for antipsychotic drug action and may be involved in the pathophysiology of schizophrenia. We have carried out a linkage study between the susceptibility gene for schizophrenia and polymorphism of the dopamine D{sub 3} receptor gene in two Japanese pedigrees. Themore » LOD scores were negative for all genetic models and for all affective status at a recombination fraction {theta} = 0. Linkage of DRD{sub 3} has been excluded for the model 1 (dominant model) and the model 3 (recessive model). The LOD score was -3.43 at {theta} = 0 for model 1 (dominant model) and broad definition of affected status. These results were consistent with previous studies. 19 refs., 2 figs., 3 tabs.« less

  4. Dopamine-Secreting Paraganglioma in the Retroperitoneum.

    PubMed

    Matsuda, Yusuke; Kimura, Noriko; Yoshimoto, Takanobu; Sekiguchi, Yoshihiro; Tomoishi, Junzo; Kasahara, Ichiro; Hara, Yoshihito; Ogawa, Yoshihiro

    2017-03-01

    Pheochromocytomas and paragangliomas, which exclusively produce dopamine, are very rare. Herein, we report for the first time a Japanese case of an exclusively dopamine-producing paraganglioma accompanied by detailed immunohistochemical analyses. A 70-year-old Japanese woman was referred to our hospital for functional examination of her left retroperitoneal mass. Her adrenal functions were normal, except for excessive dopamine secretion. After the tumorectomy, her dopamine level normalized. The histopathological diagnosis of the tumor was paraganglioma; this was confirmed by positive immunostaining of chromogranin A (CgA), tyrosine hydroxylase (TH), dopamine β-hydroxylase (DBH), and succinate dehydrogenase gene subunit B (SDHB). However, the immunostaining of CgA in the tumor cells showed peculiar dot-like staining located corresponding to Golgi complex in the perinuclear area, rather than the diffuse cytoplasmic staining usually observed in epinephrine- or norepinephrine-producing functional pheochromocytomas and paragangliomas. The immunohistochemical results suggested that the tumor cells had sparse neuroendocrine granules in the cytoplasm, resulting in inhibition of catecholamine synthesis from dopamine to norepinephrine in neurosecretory granules. This may be the mechanism responsible for exclusive dopamine secretion in the present case.

  5. Involvement of Infralimbic Prefrontal Cortex but not Lateral Habenula in Dopamine Attenuation After Chronic Mild Stress.

    PubMed

    Moreines, Jared L; Owrutsky, Zoe L; Grace, Anthony A

    2017-03-01

    Emerging evidence supports a role for dopamine in major depressive disorder (MDD). We recently reported fewer spontaneously active ventral tegmental area (VTA) dopamine neurons (ie, reduced dopamine neuron population activity) in the chronic mild stress (CMS) rodent model of MDD. In this study, we examined the role of two brain regions that have been implicated in MDD in humans, the infralimbic prefrontal cortex (ILPFC)-that is, rodent homolog of Brodmann area 25 (BA25), and the lateral habenula (LHb) in the CMS-induced attenuation of dopamine neuron activity. The impact of activating the ILPFC or LHb was evaluated using single-unit extracellular recordings of identified VTA dopamine neurons. The involvement of each region in dopamine neuron attenuation following 5-7 weeks of CMS was then evaluated by selective inactivation. Activation of either ILPFC or LHb in normal rats potently suppressed dopamine neuron population activity, but in unique patterns. ILPFC activation selectively inhibited dopamine neurons in medial VTA, which were most impacted by CMS. Conversely, LHb activation selectively inhibited dopamine neurons in lateral VTA, which were unaffected by CMS. Moreover, only ILPFC inactivation restored dopamine neuron population activity to normal levels following CMS; LHb inactivation had no restorative effect. These data suggest that, in the CMS model of MDD, the ILPFC is the primary driver of diminished dopamine neuron responses. These findings support a neural substrate for ILPFC/BA25 linking affective and motivational circuitry dysfunction in MDD.

  6. Variability in Dopamine Genes Dissociates Model-Based and Model-Free Reinforcement Learning

    PubMed Central

    Bath, Kevin G.; Daw, Nathaniel D.; Frank, Michael J.

    2016-01-01

    Considerable evidence suggests that multiple learning systems can drive behavior. Choice can proceed reflexively from previous actions and their associated outcomes, as captured by “model-free” learning algorithms, or flexibly from prospective consideration of outcomes that might occur, as captured by “model-based” learning algorithms. However, differential contributions of dopamine to these systems are poorly understood. Dopamine is widely thought to support model-free learning by modulating plasticity in striatum. Model-based learning may also be affected by these striatal effects, or by other dopaminergic effects elsewhere, notably on prefrontal working memory function. Indeed, prominent demonstrations linking striatal dopamine to putatively model-free learning did not rule out model-based effects, whereas other studies have reported dopaminergic modulation of verifiably model-based learning, but without distinguishing a prefrontal versus striatal locus. To clarify the relationships between dopamine, neural systems, and learning strategies, we combine a genetic association approach in humans with two well-studied reinforcement learning tasks: one isolating model-based from model-free behavior and the other sensitive to key aspects of striatal plasticity. Prefrontal function was indexed by a polymorphism in the COMT gene, differences of which reflect dopamine levels in the prefrontal cortex. This polymorphism has been associated with differences in prefrontal activity and working memory. Striatal function was indexed by a gene coding for DARPP-32, which is densely expressed in the striatum where it is necessary for synaptic plasticity. We found evidence for our hypothesis that variations in prefrontal dopamine relate to model-based learning, whereas variations in striatal dopamine function relate to model-free learning. SIGNIFICANCE STATEMENT Decisions can stem reflexively from their previously associated outcomes or flexibly from deliberative

  7. Variability in Dopamine Genes Dissociates Model-Based and Model-Free Reinforcement Learning.

    PubMed

    Doll, Bradley B; Bath, Kevin G; Daw, Nathaniel D; Frank, Michael J

    2016-01-27

    Considerable evidence suggests that multiple learning systems can drive behavior. Choice can proceed reflexively from previous actions and their associated outcomes, as captured by "model-free" learning algorithms, or flexibly from prospective consideration of outcomes that might occur, as captured by "model-based" learning algorithms. However, differential contributions of dopamine to these systems are poorly understood. Dopamine is widely thought to support model-free learning by modulating plasticity in striatum. Model-based learning may also be affected by these striatal effects, or by other dopaminergic effects elsewhere, notably on prefrontal working memory function. Indeed, prominent demonstrations linking striatal dopamine to putatively model-free learning did not rule out model-based effects, whereas other studies have reported dopaminergic modulation of verifiably model-based learning, but without distinguishing a prefrontal versus striatal locus. To clarify the relationships between dopamine, neural systems, and learning strategies, we combine a genetic association approach in humans with two well-studied reinforcement learning tasks: one isolating model-based from model-free behavior and the other sensitive to key aspects of striatal plasticity. Prefrontal function was indexed by a polymorphism in the COMT gene, differences of which reflect dopamine levels in the prefrontal cortex. This polymorphism has been associated with differences in prefrontal activity and working memory. Striatal function was indexed by a gene coding for DARPP-32, which is densely expressed in the striatum where it is necessary for synaptic plasticity. We found evidence for our hypothesis that variations in prefrontal dopamine relate to model-based learning, whereas variations in striatal dopamine function relate to model-free learning. Decisions can stem reflexively from their previously associated outcomes or flexibly from deliberative consideration of potential choice outcomes

  8. Brain dopamine and kinematics of graphomotor functions.

    PubMed

    Lange, Klaus W; Mecklinger, Lara; Walitza, Susanne; Becker, Georg; Gerlach, Manfred; Naumann, Markus; Tucha, Oliver

    2006-10-01

    Three experiments were performed in an attempt to achieve a better understanding of the effect of dopamine on handwriting. In the first experiment, kinematic aspects of handwriting movements were compared between healthy participants and patients with Parkinson's disease (PD) on their usual dopaminergic treatment and following withdrawal of dopaminergic medication. In the second experiment, the writing performance of healthy participants with a hyperechogenicity of the substantia nigra as detected by transcranial sonography (TCS) was compared with the performance of healthy participants with low echogenicity of the substantia nigra. The third experiment examined the effect of central dopamine reduction on kinematic aspects of handwriting movements in healthy adults using acute phenylalanine and tyrosine depletion (APTD). A digitising tablet was used for the assessment of handwriting movements. Participants were asked to perform a simple writing task. Movement time, distance, velocity, acceleration and measures of fluency of handwriting movements were measured. The kinematic analysis of handwriting movements revealed that alterations of central dopaminergic neurotransmission adversely affect movement execution during handwriting. In comparison to the automatic processing of handwriting movements displayed by control participants, participants with an altered dopaminergic neurotransmission shifted from an automatic to a controlled processing of movement execution. Central dopamine appears to be of particular importance with regard to the automatic execution of well-learned movements.

  9. Solid surface dependent layering of self-arranged structures with fibril-like assemblies of alpha-synuclein

    NASA Astrophysics Data System (ADS)

    Bukauskas, V.; Šetkus, A.; Šimkienė, I.; Tumėnas, S.; Kašalynas, I.; Rėza, A.; Babonas, J.; Časaitė, V.; Povilonienė, S.; Meškys, R.

    2012-03-01

    In present work the formation of hybrid constructions composed of alpha-synuclein-based colloidal solutions on various solid surfaces (silica coated Si, mica, CaF2 and KBr) is investigated by scanning probe microscopy, spectrocopic ellipsometry, Fourier transformed infrared spectroscopy and vibrational circular dichroism. Prior to the modification of the solids, the proteins were intentionally fibrilled under special conditions. It is proved that the multi-component coatings are self-arranged on the solid substrates. Depending on the substrate material, the interface films consisting of individual biomolecules can be detected on the solid surfaces. The coatings with fibril-like alpha-synuclein objects can be obtained on solid surfaces with negligible or comparatively thick interface films. The results are interpreted in terms of the charged surface-controlled electrostatic interaction between the substrate and the biomolecules. Solubility of solids is considered in this interpretation.

  10. Dopamine receptor blockade attenuates the general incentive motivational effects of noncontingently delivered rewards and reward-paired cues without affecting their ability to bias action selection.

    PubMed

    Ostlund, Sean B; Maidment, Nigel T

    2012-01-01

    Environmental cues affect our behavior in a variety of ways. Despite playing an invaluable role in guiding our daily activities, such cues also appear to trigger the harmful, compulsive behaviors that characterize addiction and other disorders of behavioral control. In instrumental conditioning, rewards and reward-paired cues bias action selection and invigorate reward-seeking behaviors, and appear to do so through distinct neurobehavioral processes. Although reward-paired cues are known to invigorate performance through a dopamine-dependent incentive motivational process, it is not known if dopamine also mediates the influence of rewards and reward-paired cues over action selection. The current study contrasted the effects of systemic administration of the nonspecific dopamine receptor antagonist flupentixol on response invigoration and action bias in Pavlovian-instrumental transfer, a test of cue-elicited responding, and in instrumental reinstatement, a test of noncontingent reward-elicited responding. Hungry rats were trained on two different stimulus-outcome relationships (eg, tone-grain pellets and noise-sucrose solution) and two different action-outcome relationships (eg, left press-grain and right press-sucrose). At test, we found that flupentixol pretreatment blocked the response invigoration generated by the cues but spared their ability to bias action selection to favor the action whose outcome was signaled by the cue being presented. The response-biasing influence of noncontingent reward deliveries was also unaffected by flupentixol. Interestingly, although flupentixol had a modest effect on the immediate response invigoration produced by those rewards, it was particularly potent in countering the lingering enhancement of responding produced by multiple reward deliveries. These findings indicate that dopamine mediates the general incentive motivational effects of noncontingent rewards and reward-paired cues but does not support their ability to bias

  11. Cross-hemispheric dopamine projections have functional significance

    PubMed Central

    Fox, Megan E.; Mikhailova, Maria A.; Bass, Caroline E.; Takmakov, Pavel; Gainetdinov, Raul R.; Budygin, Evgeny A.; Wightman, R. Mark

    2016-01-01

    Dopamine signaling occurs on a subsecond timescale, and its dysregulation is implicated in pathologies ranging from drug addiction to Parkinson’s disease. Anatomic evidence suggests that some dopamine neurons have cross-hemispheric projections, but the significance of these projections is unknown. Here we report unprecedented interhemispheric communication in the midbrain dopamine system of awake and anesthetized rats. In the anesthetized rats, optogenetic and electrical stimulation of dopamine cells elicited physiologically relevant dopamine release in the contralateral striatum. Contralateral release differed between the dorsal and ventral striatum owing to differential regulation by D2-like receptors. In the freely moving animals, simultaneous bilateral measurements revealed that dopamine release synchronizes between hemispheres and intact, contralateral projections can release dopamine in the midbrain of 6-hydroxydopamine–lesioned rats. These experiments are the first, to our knowledge, to show cross-hemispheric synchronicity in dopamine signaling and support a functional role for contralateral projections. In addition, our data reveal that psychostimulants, such as amphetamine, promote the coupling of dopamine transients between hemispheres. PMID:27298371

  12. Computational Systems Analysis of Dopamine Metabolism

    PubMed Central

    Qi, Zhen; Miller, Gary W.; Voit, Eberhard O.

    2008-01-01

    A prominent feature of Parkinson's disease (PD) is the loss of dopamine in the striatum, and many therapeutic interventions for the disease are aimed at restoring dopamine signaling. Dopamine signaling includes the synthesis, storage, release, and recycling of dopamine in the presynaptic terminal and activation of pre- and post-synaptic receptors and various downstream signaling cascades. As an aid that might facilitate our understanding of dopamine dynamics in the pathogenesis and treatment in PD, we have begun to merge currently available information and expert knowledge regarding presynaptic dopamine homeostasis into a computational model, following the guidelines of biochemical systems theory. After subjecting our model to mathematical diagnosis and analysis, we made direct comparisons between model predictions and experimental observations and found that the model exhibited a high degree of predictive capacity with respect to genetic and pharmacological changes in gene expression or function. Our results suggest potential approaches to restoring the dopamine imbalance and the associated generation of oxidative stress. While the proposed model of dopamine metabolism is preliminary, future extensions and refinements may eventually serve as an in silico platform for prescreening potential therapeutics, identifying immediate side effects, screening for biomarkers, and assessing the impact of risk factors of the disease. PMID:18568086

  13. Adenosine transiently modulates stimulated dopamine release in the caudate putamen via A1 receptors

    PubMed Central

    Ross, Ashley E.; Venton, B. Jill

    2014-01-01

    Adenosine modulates dopamine in the brain via A1 and A2A receptors, but that modulation has only been characterized on a slow time scale. Recent studies have characterized a rapid signaling mode of adenosine that suggests a possible rapid modulatory role. Here, fast-scan cyclic voltammetry was used to characterize the extent to which transient adenosine changes modulate stimulated dopamine release (5 pulses at 60 Hz) in rat caudate putamen brain slices. Exogenous adenosine was applied and dopamine concentration monitored. Adenosine only modulated dopamine when it was applied 2 or 5 s before stimulation. Longer time intervals and bath application of 5 µM adenosine did not decrease dopamine release. Mechanical stimulation of endogenous adenosine 2s before dopamine stimulation also decreased stimulated dopamine release by 41 ± 7 %, similar to the 54 ± 6 % decrease in dopamine after exogenous adenosine application. Dopamine inhibition by transient adenosine was recovered within 10 minutes. The A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) blocked the dopamine modulation, whereas dopamine modulation was unaffected by the A2A receptor antagonist SCH 442416. Thus, transient adenosine changes can transiently modulate phasic dopamine release via A1 receptors. These data demonstrate that adenosine has a rapid, but transient, modulatory role in the brain. PMID:25219576

  14. Pharmacological Chaperones of the Dopamine Transporter Rescue Dopamine Transporter Deficiency Syndrome Mutations in Heterologous Cells.

    PubMed

    Beerepoot, Pieter; Lam, Vincent M; Salahpour, Ali

    2016-10-14

    A number of pathological conditions have been linked to mutations in the dopamine transporter gene, including hereditary dopamine transporter deficiency syndrome (DTDS). DTDS is a rare condition that is caused by autosomal recessive loss-of-function mutations in the dopamine transporter (DAT), which often affects transporter trafficking and folding. We examined the possibility of using pharmacological chaperones of DAT to rescue DTDS mutations. After screening a set of known DAT ligands for their ability to increase DAT surface expression, we found that bupropion and ibogaine increased DAT surface expression, whereas others, including cocaine and methylphenidate, had no effect. Bupropion and ibogaine increased wild type DAT protein levels and also promoted maturation of the endoplasmic reticulum (ER)-retained DAT mutant K590A. Rescue of K590A could be blocked by inhibiting ER to Golgi transport using brefeldin A. Furthermore, knockdown of coat protein complex II (COPII) component SEC24D, which is important in the ER export of wild type DAT, also blocked the rescue effects of bupropion and ibogaine. These data suggest that bupropion and ibogaine promote maturation of DAT by acting as pharmacological chaperones in the ER. Importantly, both drugs rescue DAT maturation and functional activity of the DTDS-associated mutations A314V and R445C. Together, these results are the first demonstration of pharmacological chaperoning of DAT and suggest this may be a viable approach to increase DAT levels in DTDS and other conditions associated with reduced DAT function. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Does cannabis affect dopaminergic signaling in the human brain? A systematic review of evidence to date.

    PubMed

    Sami, Musa Basser; Rabiner, Eugenii A; Bhattacharyya, Sagnik

    2015-08-01

    A significant body of epidemiological evidence has linked psychotic symptoms with both acute and chronic use of cannabis. Precisely how these effects of THC are mediated at the neurochemical level is unclear. While abnormalities in multiple pathways may lead to schizophrenia, an abnormality in dopamine neurotransmission is considered to be the final common abnormality. One would thus expect cannabis use to be associated with dopamine signaling alterations. This is the first systematic review of all studies, both observational as well as experimental, examining the acute as well as chronic effect of cannabis or its main psychoactive ingredient, THC, on the dopamine system in man. We aimed to review all studies conducted in man, with any reported neurochemical outcomes related to the dopamine system after cannabis, cannabinoid or endocannabinoid administration or use. We identified 25 studies reporting outcomes on over 568 participants, of which 244 participants belonged to the cannabis/cannabinoid exposure group. In man, there is as yet little direct evidence to suggest that cannabis use affects acute striatal dopamine release or affects chronic dopamine receptor status in healthy human volunteers. However some work has suggested that acute cannabis exposure increases dopamine release in striatal and pre-frontal areas in those genetically predisposed for, or at clinical high risk of psychosis. Furthermore, recent studies are suggesting that chronic cannabis use blunts dopamine synthesis and dopamine release capacity. Further well-designed studies are required to definitively delineate the effects of cannabis use on the dopaminergic system in man. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  16. Ih Current Is Necessary to Maintain Normal Dopamine Fluctuations and Sleep Consolidation in Drosophila

    PubMed Central

    Gonzalo-Gomez, Alicia; Turiegano, Enrique; León, Yolanda; Molina, Isabel; Torroja, Laura; Canal, Inmaculada

    2012-01-01

    HCN channels are becoming pharmacological targets mainly in cardiac diseases. But apart from their well-known role in heart pacemaking, these channels are widely expressed in the nervous system where they contribute to the neuron firing pattern. Consequently, abolishing Ih current might have detrimental consequences in a big repertoire of behavioral traits. Several studies in mammals have identified the Ih current as an important determinant of the firing activity of dopaminergic neurons, and recent evidences link alterations in this current to various dopamine-related disorders. We used the model organism Drosophila melanogaster to investigate how lack of Ih current affects dopamine levels and the behavioral consequences in the sleep∶activity pattern. Unlike mammals, in Drosophila there is only one gene encoding HCN channels. We generated a deficiency of the DmIh core gene region and measured, by HPLC, levels of dopamine. Our data demonstrate daily variations of dopamine in wild-type fly heads. Lack of Ih current dramatically alters dopamine pattern, but different mechanisms seem to operate during light and dark conditions. Behaviorally, DmIh mutant flies display alterations in the rest∶activity pattern, and altered circadian rhythms. Our data strongly suggest that Ih current is necessary to prevent dopamine overproduction at dark, while light input allows cycling of dopamine in an Ih current dependent manner. Moreover, lack of Ih current results in behavioral defects that are consistent with altered dopamine levels. PMID:22574167

  17. Ih current is necessary to maintain normal dopamine fluctuations and sleep consolidation in Drosophila.

    PubMed

    Gonzalo-Gomez, Alicia; Turiegano, Enrique; León, Yolanda; Molina, Isabel; Torroja, Laura; Canal, Inmaculada

    2012-01-01

    HCN channels are becoming pharmacological targets mainly in cardiac diseases. But apart from their well-known role in heart pacemaking, these channels are widely expressed in the nervous system where they contribute to the neuron firing pattern. Consequently, abolishing Ih current might have detrimental consequences in a big repertoire of behavioral traits. Several studies in mammals have identified the Ih current as an important determinant of the firing activity of dopaminergic neurons, and recent evidences link alterations in this current to various dopamine-related disorders. We used the model organism Drosophila melanogaster to investigate how lack of Ih current affects dopamine levels and the behavioral consequences in the sleep:activity pattern. Unlike mammals, in Drosophila there is only one gene encoding HCN channels. We generated a deficiency of the DmIh core gene region and measured, by HPLC, levels of dopamine. Our data demonstrate daily variations of dopamine in wild-type fly heads. Lack of Ih current dramatically alters dopamine pattern, but different mechanisms seem to operate during light and dark conditions. Behaviorally, DmIh mutant flies display alterations in the rest:activity pattern, and altered circadian rhythms. Our data strongly suggest that Ih current is necessary to prevent dopamine overproduction at dark, while light input allows cycling of dopamine in an Ih current dependent manner. Moreover, lack of Ih current results in behavioral defects that are consistent with altered dopamine levels.

  18. A role of BAG3 in regulating SNCA/α-synuclein clearance via selective macroautophagy.

    PubMed

    Cao, Yu-Lan; Yang, Ya-Ping; Mao, Cheng-Jie; Zhang, Xiao-Qi; Wang, Chen-Tao; Yang, Jing; Lv, Dong-Jun; Wang, Fen; Hu, Li-Fang; Liu, Chun-Feng

    2017-12-01

    Many studies reveal that BAG3 plays a critical role in the regulation of protein degradation via macroautophagy. However, it remains unknown whether BAG3 affects the quality control of α-synuclein (SNCA), a Parkinson's disease-related protein. In this study, we demonstrated the increases of BAG3 expression in the ventral midbrain of SNCA A53T transgenic mice and also in MG132-treated PC12 cells overexpressing wild-type SNCA (SNCA WT -PC12). Moreover, we showed that BAG3 overexpression was sufficient to enhance the autophagy activity while knockdown of Bag3 reduced it in SNCA WT -PC12 cells. Immunoprecipitation revealed that BAG3 interacted with heat shock protein 70 and sequestosome 1. The immunostaining also showed the perinuclear accumulation and colocalization of BAG3 with these 2 proteins, as well as with LC3 dots in tyrosine hydroxylase-positive neurons in the midbrain of SNCA A53T mice. BAG3 overexpression was able to modulate SNCA degradation via macroautophagy which was prevented by Atg5 knockdown. Taken together, these results indicate that BAG3 plays a relevant role in regulating SNCA clearance via macroautophagy, and the heat shock protein 70-BAG3-sequestosome 1 complex may be involved in this process. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Paraquat affects mitochondrial bioenergetics, dopamine system expression, and locomotor activity in zebrafish (Danio rerio).

    PubMed

    Wang, Xiao H; Souders, Christopher L; Zhao, Yuan H; Martyniuk, Christopher J

    2018-01-01

    The dipyridyl herbicide paraquat induces oxidative stress in cells and is implicated in adult neurodegenerative diseases. However, less is known about paraquat toxicity in early stages of vertebrate development. To address this gap, zebrafish (Danio rerio) embryos were exposed to 1, 10 and 100 μM paraquat for 96 h. Paraquat did not induce significant mortality nor deformity in embryos and larvae, but it did accelerate time to hatch. To evaluate whether mitochondrial respiration was related to earlier hatch times, oxygen consumption rate was measured in whole embryos. Maximal respiration of embryos exposed to 100 μM paraquat for 24 h was reduced by more than 70%, suggesting that paraquat negatively impacts mitochondrial bioenergetics in early development. Based upon this evidence for mitochondrial dysfunction, transcriptional responses of oxidative stress- and apoptosis-related genes were measured. Fish exposed to 1 μM paraquat showed higher expression levels of superoxide dismutase 2, heat shock protein 70, Bcl-2-associated X protein, and B-cell CLL/lymphoma 2a compared to control fish. No differences among groups were detected in larvae exposed to 10 and 100 μM paraquat, suggesting a non-monotonic response. We also measured endpoints related to larval behavior and dopaminergic signaling as paraquat is associated with degeneration of dopamine neurons. Locomotor activity was stimulated with 100 μM paraquat and dopamine transporter and dopamine receptor 3 mRNA levels were increased in larvae exposed to 1 μM paraquat, interpreted to be a compensatory response at lower concentrations. This study improves mechanistic understanding into the toxic actions of paraquat on early developmental stages. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. A peptide disrupting the D2R-DAT interaction protects against dopamine neurotoxicity.

    PubMed

    Su, Ping; Liu, Fang

    2017-09-01

    Dopamine reuptake from extracellular space to cytosol leads to accumulation of dopamine, which triggers neurotoxicity in dopaminergic neurons. Previous studies have shown that both dopamine D2 receptor (D2R) and dopamine transporter (DAT) are involved in dopamine neurotoxicity. However, blockade of either D2R or DAT causes side effects due to antagonism of other physiological functions of these two proteins. We previously found that DAT can form a protein complex with D2R and its cell surface expression is facilitated via D2R-DAT interaction, which regulates dopamine reuptake and intracellular dopamine levels. Here we found that an interfering peptide (DAT-S1) disrupting the D2R-DAT interaction protects neurons against dopamine neurotoxicity, and this effect is mediated by inhibiting DAT cell surface expression and inhibiting both caspase-3 and PARP-1 cleavage. This study demonstrates the role of the D2R-DAT complex in dopamine neurotoxicity and investigated the potential mechanisms, which might help better understand the mechanisms of dopamine neurotoxicity. The peptide may provide some insights to improve treatments for dopamine neurotoxicity and related diseases, such as Parkinson's disease, as well as methamphetamine- and 3,4-methsylenedioxy methamphetamine-induced neurotoxicity. Copyright © 2017. Published by Elsevier Inc.

  1. Effects of dopaminergic modulation on electrophysiological brain response to affective stimuli.

    PubMed

    Franken, Ingmar H A; Nijs, Ilse; Pepplinkhuizen, Lolke

    2008-01-01

    Several theoretical accounts of the role of dopamine suggest that dopamine has an influence on the processing of affective stimuli. There is some indirect evidence for this from studies showing an association between the treatment with dopaminergic agents and self-reported affect. We addressed this issue directly by examining the electrophysiological correlates of affective picture processing during a single-dose treatment with a dopamine D2 agonist (bromocriptine), a dopamine D2 antagonist (haloperidol), and a placebo. We compared early and late event-related brain potentials (ERPs) that have been associated with affective processing in the three medication treatment conditions in a randomized double-blind crossover design amongst healthy males. In each treatment condition, subjects attentively watched neutral, pleasant, and unpleasant pictures while ERPs were recorded. Results indicate that neither bromocriptine nor haloperidol has a selective effect on electrophysiological indices of affective processing. In concordance with this, no effects of dopaminergic modulation on self-reported positive or negative affect was observed. In contrast, bromocriptine decreased overall processing of all stimulus categories regardless of their affective content. The results indicate that dopaminergic D2 receptors do not seem to play a crucial role in the selective processing of affective visual stimuli.

  2. Recovery of dopamine transporters with methamphetamine detoxification is not linked to changes in dopamine release.

    PubMed

    Volkow, Nora D; Wang, Gene-Jack; Smith, Lisa; Fowler, Joanna S; Telang, Frank; Logan, Jean; Tomasi, Dardo

    2015-11-01

    Methamphetamine's widepread abuse and concerns that it might increase Parkinson's disease led us to assess if the reported loss of dopamine transporters (DAT) in methamphetamine abusers (MA) reflected damage to dopamine neurons. Using PET with [(11)C]cocaine to measure DAT, and with [(11)C]raclopride to measure dopamine release (assessed as changes in specific binding of [(11)C]raclopride between placebo and methylphenidate), which was used as a marker of dopamine neuronal function, we show that MA (n=16), tested during early detoxification, had lower DAT (20-30%) but overall normal DA release in striatum (except for a small decrease in left putamen), when compared to controls (n=15). In controls, DAT were positively correlated with DA release (higher DAT associated with larger DA increases), consistent with DAT serving as markers of DA terminals. In contrast, MA showed a trend for a negative correlation (p=0.07) (higher DAT associated with lower DA increases), consistent with reduced DA re-uptake following DAT downregulation. MA who remained abstinent nine-months later (n=9) showed significant increases in DAT (20%) but methylphenidate-induced dopamine increases did not change. In contrast, in controls, DAT did not change when retested 9 months later but methylphenidate-induced dopamine increases in ventral striatum were reduced (p=0.05). Baseline D2/D3 receptors in caudate were lower in MA than in controls and did not change with detoxification, nor did they change in the controls upon retest. The loss of DAT in the MA, which was not associated with a concomitant reduction in dopamine release as would have been expected if DAT loss reflected DA terminal degneration; as well as the recovery of DAT after protracted detoxification, which was not associated with increased dopamine release as would have been expected if DAT increases reflected terminal regeneration, indicate that the loss of DAT in these MA does not reflect degeneration of dopamine terminals

  3. Recovery of dopamine transporters with methamphetamine detoxification is not linked to changes in dopamine release

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Volkow, Nora D.; Wang, Gene-Jack; Smith, Lisa

    Metamphetamine’s widepread abuse and concerns that it may increase Parkinson’s disease led us to assess if the reported loss of dopamine transporters (DAT) in methamphetamine abusers (MA) reflected damage to dopamine neurons. Using PET with [ 11C]cocaine to measure DAT, and with [ 11C]raclopride to measure dopamine release (assessed as changes in specific binding of [ 11C]raclopride between placebo and methylphenidate), which was used as marker of dopamine neuronal function, we show that MA (n=16), tested during early detoxification, had lower DAT (20-30%) but overall normal DA release in striatum (except for a small decrease in left putamen), when comparedmore » to controls (n=15). In controls, DAT were positively correlated with DA release (higher DAT associated with larger DA increases), consistent with DAT serving as markers of DA terminals. In contrast, MA showed a trend for a negative correlation (p=0.07) (higher DAT associated with lower DA increases), consistent with reduced DA re-uptake following DAT downregulation. MA who remained abstinent nine-months later (n=9) showed significant increases in DAT (20%) but methylphenidate-induced dopamine increases did not change. In contrast, in controls, DAT did not change when retested 9 months later but methylphenidate-induced dopamine increases in ventral striatum were reduced (p=0.05). Baseline D2/D3 receptors in caudate were lower in MA than in controls and did not change with detoxification, nor did they change in the controls upon retest. The loss of DAT in the MA, which was not associated with a concomitant reduction in dopamine release as would have been expected if DAT loss reflected DA terminal degneration; as well as the recovery of DAT after protracted detoxification, which was not associated with increased dopamine release as would have been expected if DAT increases reflected terminal regeneration, indicate that the loss of DAT in these MA does not reflect degeneration of dopamine terminals.« less

  4. Recovery of dopamine transporters with methamphetamine detoxification is not linked to changes in dopamine release

    DOE PAGES

    Volkow, Nora D.; Wang, Gene-Jack; Smith, Lisa; ...

    2015-07-21

    Metamphetamine’s widepread abuse and concerns that it may increase Parkinson’s disease led us to assess if the reported loss of dopamine transporters (DAT) in methamphetamine abusers (MA) reflected damage to dopamine neurons. Using PET with [ 11C]cocaine to measure DAT, and with [ 11C]raclopride to measure dopamine release (assessed as changes in specific binding of [ 11C]raclopride between placebo and methylphenidate), which was used as marker of dopamine neuronal function, we show that MA (n=16), tested during early detoxification, had lower DAT (20-30%) but overall normal DA release in striatum (except for a small decrease in left putamen), when comparedmore » to controls (n=15). In controls, DAT were positively correlated with DA release (higher DAT associated with larger DA increases), consistent with DAT serving as markers of DA terminals. In contrast, MA showed a trend for a negative correlation (p=0.07) (higher DAT associated with lower DA increases), consistent with reduced DA re-uptake following DAT downregulation. MA who remained abstinent nine-months later (n=9) showed significant increases in DAT (20%) but methylphenidate-induced dopamine increases did not change. In contrast, in controls, DAT did not change when retested 9 months later but methylphenidate-induced dopamine increases in ventral striatum were reduced (p=0.05). Baseline D2/D3 receptors in caudate were lower in MA than in controls and did not change with detoxification, nor did they change in the controls upon retest. The loss of DAT in the MA, which was not associated with a concomitant reduction in dopamine release as would have been expected if DAT loss reflected DA terminal degneration; as well as the recovery of DAT after protracted detoxification, which was not associated with increased dopamine release as would have been expected if DAT increases reflected terminal regeneration, indicate that the loss of DAT in these MA does not reflect degeneration of dopamine terminals.« less

  5. A computational model of Dopamine and Acetylcholine aberrant learning in Basal Ganglia.

    PubMed

    Baston, Chiara; Ursino, Mauro

    2015-01-01

    Basal Ganglia (BG) are implied in many motor and cognitive tasks, such as action selection, and have a central role in many pathologies, primarily Parkinson Disease. In the present work, we use a recently developed biologically inspired BG model to analyze how the dopamine (DA) level can affect the temporal response during action selection, and the capacity to learn new actions following rewards and punishments. The model incorporates the 3 main pathways (direct, indirect and hyperdirect) working in BG functioning. The behavior of 2 alternative networks (the first with normal DA levels, the second with reduced DA) is analyzed both in untrained conditions, and during training performed in different epochs. The results show that reduced DA causes delayed temporal responses in the untrained network, and difficult of learning during training, characterized by the necessity of much more epochs. The results provide interesting hints to understand the behavior of healthy and dopamine depleted subjects, such as parkinsonian patients.

  6. α-Synuclein and huntingtin exon 1 amyloid fibrils bind laterally to the cellular membrane.

    PubMed

    Monsellier, Elodie; Bousset, Luc; Melki, Ronald

    2016-01-13

    Fibrillar aggregates involved in neurodegenerative diseases have the ability to spread from one cell to another in a prion-like manner. The underlying molecular mechanisms, in particular the binding mode of the fibrils to cell membranes, are poorly understood. In this work we decipher the modality by which aggregates bind to the cellular membrane, one of the obligatory steps of the propagation cycle. By characterizing the binding properties of aggregates made of α-synuclein or huntingtin exon 1 protein displaying similar composition and structure but different lengths to mammalian cells we demonstrate that in both cases aggregates bind laterally to the cellular membrane, with aggregates extremities displaying little or no role in membrane binding. Lateral binding to artificial liposomes was also observed by transmission electron microscopy. In addition we show that although α-synuclein and huntingtin exon 1 fibrils bind both laterally to the cellular membrane, their mechanisms of interaction differ. Our findings have important implications for the development of future therapeutic tools that aim to block protein aggregates propagation in the brain.

  7. α-Synuclein and huntingtin exon 1 amyloid fibrils bind laterally to the cellular membrane

    PubMed Central

    Monsellier, Elodie; Bousset, Luc; Melki, Ronald

    2016-01-01

    Fibrillar aggregates involved in neurodegenerative diseases have the ability to spread from one cell to another in a prion-like manner. The underlying molecular mechanisms, in particular the binding mode of the fibrils to cell membranes, are poorly understood. In this work we decipher the modality by which aggregates bind to the cellular membrane, one of the obligatory steps of the propagation cycle. By characterizing the binding properties of aggregates made of α-synuclein or huntingtin exon 1 protein displaying similar composition and structure but different lengths to mammalian cells we demonstrate that in both cases aggregates bind laterally to the cellular membrane, with aggregates extremities displaying little or no role in membrane binding. Lateral binding to artificial liposomes was also observed by transmission electron microscopy. In addition we show that although α-synuclein and huntingtin exon 1 fibrils bind both laterally to the cellular membrane, their mechanisms of interaction differ. Our findings have important implications for the development of future therapeutic tools that aim to block protein aggregates propagation in the brain. PMID:26757959

  8. Cu(II) promotes amyloid pore formation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Hangyu, E-mail: hangyuz@uw.edu; Rochet, Jean-Christophe; Stanciu, Lia A.

    2015-08-14

    The aggregation of α-synuclein is associated with dopamine neuron death in Parkinson's disease. There is controversy in the field over the question of which species of the aggregates, fibrils or protofibrils, are toxic. Moreover, compelling evidence suggested the exposure to heavy metals to be a risk of PD. Nevertheless, the mechanism of metal ions in promoting PD remains unclear. In this research, we investigated the structural basis of Cu(II) induced aggregation of α-synuclein. Using transmission electron microscopy experiments, Cu(II) was found to promote in vitro aggregation of α-synuclein by facilitating annular protofibril formation rather than fibril formation. Furthermore, neuroprotective baicalein disaggregatedmore » annular protofibrils accompanied by considerable decrease of β-sheet content. These results strongly support the hypothesis that annular protofibrils are the toxic species, rather than fibrils, thereby inspiring us to search novel therapeutic strategies for the suppression of the toxic annular protofibril formation. - Highlights: • Cu(II) promoted the annular protofibril formation of α-synuclein in vitro. • Cu(II) postponed the in vitro fibrillization of α-synuclein. • Neuroprotective baicalein disaggregated annular protofibrils.« less

  9. Dopamine-Independent Locomotor Actions of Amphetamines in a Novel Acute Mouse Model of Parkinson Disease

    PubMed Central

    Sotnikova, Tatyana D; Beaulieu, Jean-Martin; Barak, Larry S; Wetsel, William C; Gainetdinov, Raul R

    2005-01-01

    Brain dopamine is critically involved in movement control, and its deficiency is the primary cause of motor symptoms in Parkinson disease. Here we report development of an animal model of acute severe dopamine deficiency by using mice lacking the dopamine transporter. In the absence of transporter-mediated recycling mechanisms, dopamine levels become entirely dependent on de novo synthesis. Acute pharmacological inhibition of dopamine synthesis in these mice induces transient elimination of striatal dopamine accompanied by the development of a striking behavioral phenotype manifested as severe akinesia, rigidity, tremor, and ptosis. This phenotype can be reversed by administration of the dopamine precursor, L-DOPA, or by nonselective dopamine agonists. Surprisingly, several amphetamine derivatives were also effective in reversing these behavioral abnormalities in a dopamine-independent manner. Identification of dopamine transporter- and dopamine-independent locomotor actions of amphetamines suggests a novel paradigm in the search for prospective anti-Parkinsonian drugs. PMID:16050778

  10. Dopamine Dynamics during Continuous Intracranial Self-Stimulation: Effect of Waveform on Fast-Scan Cyclic Voltammetry Data

    PubMed Central

    2016-01-01

    The neurotransmitter dopamine is heavily implicated in intracranial self-stimulation (ICSS). Many drugs of abuse that affect ICSS behavior target the dopaminergic system, and optogenetic activation of dopamine neurons is sufficient to support self-stimulation. However, the patterns of phasic dopamine release during ICSS remain unclear. Early ICSS studies using fast-scan cyclic voltammetry (FSCV) rarely observed phasic dopamine release, which led to the surprising conclusion that it is dissociated from ICSS. However, several advances in the sensitivity (i.e., the use of waveforms with extended anodic limits) and analysis (i.e., principal component regression) of FSCV measurements have made it possible to detect smaller, yet physiologically relevant, dopamine release events. Therefore, this study revisits phasic dopamine release during ICSS using these tools. It was found that the anodic limit of the voltammetric waveform has a substantial effect on the patterns of dopamine release observed during continuous ICSS. While data collected with low anodic limits (i.e., +1.0 V) support the disappearance of phasic dopamine release observed in previous investigation, the use of high anodic limits (+1.3 V, +1.4 V) allows for continual detection of dopamine release throughout ICSS. However, the +1.4 V waveform lacks the ability to resolve narrowly spaced events, with the best balance of temporal resolution and sensitivity provided by the +1.3 V waveform. Ultimately, it is revealed that the amplitude of phasic dopamine release decays but does not fully disappear during continuous ICSS. PMID:27548680

  11. Dopamine Dynamics during Continuous Intracranial Self-Stimulation: Effect of Waveform on Fast-Scan Cyclic Voltammetry Data.

    PubMed

    Rodeberg, Nathan T; Johnson, Justin A; Bucher, Elizabeth S; Wightman, R Mark

    2016-11-16

    The neurotransmitter dopamine is heavily implicated in intracranial self-stimulation (ICSS). Many drugs of abuse that affect ICSS behavior target the dopaminergic system, and optogenetic activation of dopamine neurons is sufficient to support self-stimulation. However, the patterns of phasic dopamine release during ICSS remain unclear. Early ICSS studies using fast-scan cyclic voltammetry (FSCV) rarely observed phasic dopamine release, which led to the surprising conclusion that it is dissociated from ICSS. However, several advances in the sensitivity (i.e., the use of waveforms with extended anodic limits) and analysis (i.e., principal component regression) of FSCV measurements have made it possible to detect smaller, yet physiologically relevant, dopamine release events. Therefore, this study revisits phasic dopamine release during ICSS using these tools. It was found that the anodic limit of the voltammetric waveform has a substantial effect on the patterns of dopamine release observed during continuous ICSS. While data collected with low anodic limits (i.e., +1.0 V) support the disappearance of phasic dopamine release observed in previous investigation, the use of high anodic limits (+1.3 V, +1.4 V) allows for continual detection of dopamine release throughout ICSS. However, the +1.4 V waveform lacks the ability to resolve narrowly spaced events, with the best balance of temporal resolution and sensitivity provided by the +1.3 V waveform. Ultimately, it is revealed that the amplitude of phasic dopamine release decays but does not fully disappear during continuous ICSS.

  12. Developmental imaging genetics: linking dopamine function to adolescent behavior.

    PubMed

    Padmanabhan, Aarthi; Luna, Beatriz

    2014-08-01

    Adolescence is a period of development characterized by numerous neurobiological changes that significantly influence behavior and brain function. Adolescence is of particular interest due to the alarming statistics indicating that mortality rates increase two to three-fold during this time compared to childhood, due largely to a peak in risk-taking behaviors resulting from increased impulsivity and sensation seeking. Furthermore, there exists large unexplained variability in these behaviors that are in part mediated by biological factors. Recent advances in molecular genetics and functional neuroimaging have provided a unique and exciting opportunity to non-invasively study the influence of genetic factors on brain function in humans. While genes do not code for specific behaviors, they do determine the structure and function of proteins that are essential to the neuronal processes that underlie behavior. Therefore, studying the interaction of genotype with measures of brain function over development could shed light on critical time points when biologically mediated individual differences in complex behaviors emerge. Here we review animal and human literature examining the neurobiological basis of adolescent development related to dopamine neurotransmission. Dopamine is of critical importance because of (1) its role in cognitive and affective behaviors, (2) its role in the pathogenesis of major psychopathology, and (3) the protracted development of dopamine signaling pathways over adolescence. We will then focus on current research examining the role of dopamine-related genes on brain function. We propose the use of imaging genetics to examine the influence of genetically mediated dopamine variability on brain function during adolescence, keeping in mind the limitations of this approach. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Site-specific structural dynamics of α-Synuclein revealed by time-resolved fluorescence spectroscopy: a review

    NASA Astrophysics Data System (ADS)

    Sahay, Shruti; Krishnamoorthy, G.; Maji, Samir K.

    2016-12-01

    Aggregation of α-Synuclein (α-Syn) into amyloid fibrils is known to be associated with the pathogenesis of Parkinson’s disease (PD). Several missense mutations of the α-Syn gene have been associated with rare, early onset familial forms of PD. Despite several studies done so far, the local/residue-level structure and dynamics of α-Syn in its soluble and aggregated fibril form and how these are affected by the familial PD associated mutations are still not clearly understood. Here, we review studies performed by our group as well as other research groups, where time-resolved fluorescence spectroscopy has been used to understand the site-specific structure and dynamics of α-Syn under physiological conditions as well as under conditions that alter the aggregation properties of the protein such as low pH, high temperature, presence of membrane mimics and familial PD associated mutations. These studies have provided important insights into the critical structural properties of α-Syn that may govern its aggregation. The review also highlights time-resolved fluorescence as a promising tool to study the critical conformational transitions associated with early oligomerization of α-Syn, which are otherwise not accessible using other commonly used techniques such as thioflavin T (ThT) binding assay.

  14. Dopamine dynamics during emotional cognitive processing: Implications of the specific actions of clozapine compared with haloperidol.

    PubMed

    Kawano, Masahiko; Oshibuchi, Hidehiro; Kawano, Takaaki; Muraoka, Hiroyuki; Tsutsumi, Takahiro; Yamada, Makiko; Inada, Ken; Ishigooka, Jun

    2016-06-15

    Clozapine has improved efficacy relative to typical antipsychotics in schizophrenia treatment, particularly regarding emotional symptoms. However, the mechanisms underlying its therapeutic benefits remain unclear. Using a methamphetamine-sensitised rat model, we measured changes in dopamine levels in the amygdalae in response to a fear-conditioned cue, serving as a biochemical marker of emotional cognitive processing disruption in psychosis, for analysing the biochemical mechanisms associated with the clinical benefits of clozapine. We also compared how clozapine and haloperidol affected basal dopamine levels and phasic dopamine release in response to the fear-conditioned cue. Extracellular dopamine was collected from the amygdalae of freely moving rats via microdialysis and was analysed by high-performance liquid chromatography. Clozapine or haloperidol was injected during microdialysis, followed by exposure to the fear-conditioned cue. We analysed the ratio of change in dopamine levels from baseline. Haloperidol treatment increased the baseline dopamine levels in both non-sensitised and sensitised rats. Conversely, clozapine only increased the basal dopamine levels in the non-sensitised rats, but not in the sensitised rats. Although both antipsychotics attenuated phasic dopamine release in both the non-sensitised and sensitised rats, the attenuation extent was greater for clozapine than for haloperidol under both dopaminergic conditions. Our findings indicate that stabilized dopamine release in the amygdalae is a common therapeutic mechanism of antipsychotic action during emotional processing. However, the specific dopaminergic state-dependent action of clozapine on both basal dopamine levels and stress-induced dopamine release may be the underlying mechanism for its superior clinical effect on emotional cognitive processing in patients with schizophrenia. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Regulator of G protein signaling-12 modulates the dopamine transporter in ventral striatum and locomotor responses to psychostimulants.

    PubMed

    Gross, Joshua D; Kaski, Shane W; Schroer, Adam B; Wix, Kimberley A; Siderovski, David P; Setola, Vincent

    2018-02-01

    Regulators of G protein signaling are proteins that accelerate the termination of effector stimulation after G protein-coupled receptor activation. Many regulators of G protein signaling proteins are highly expressed in the brain and therefore considered potential drug discovery targets for central nervous system pathologies; for example, here we show that RGS12 is highly expressed in microdissected mouse ventral striatum. Given a role for the ventral striatum in psychostimulant-induced locomotor activity, we tested whether Rgs12 genetic ablation affected behavioral responses to amphetamine and cocaine. RGS12 loss significantly decreased hyperlocomotion to lower doses of both amphetamine and cocaine; however, other outcomes of administration (sensitization and conditioned place preference) were unaffected, suggesting that RGS12 does not function in support of the rewarding properties of these psychostimulants. To test whether observed response changes upon RGS12 loss were caused by changes to dopamine transporter expression and/or function, we prepared crude membranes from the brains of wild-type and RGS12-null mice and measured dopamine transporter-selective [ 3 H]WIN 35428 binding, revealing an increase in dopamine transporter levels in the ventral-but not dorsal-striatum of RGS12-null mice. To address dopamine transporter function, we prepared striatal synaptosomes and measured [ 3 H]dopamine uptake. Consistent with increased [ 3 H]WIN 35428 binding, dopamine transporter-specific [ 3 H]dopamine uptake in RGS12-null ventral striatal synaptosomes was found to be increased. Decreased amphetamine-induced locomotor activity and increased [ 3 H]WIN 35428 binding were recapitulated with an independent RGS12-null mouse strain. Thus, we propose that RGS12 regulates dopamine transporter expression and function in the ventral striatum, affecting amphetamine- and cocaine-induced increases in dopamine levels that specifically elicit acute hyperlocomotor responses.

  16. Estradiol, dopamine and motivation.

    PubMed

    Yoest, Katie E; Cummings, Jennifer A; Becker, Jill B

    2014-01-01

    The gonadal hormone estradiol modulates mesolimbic dopamine systems in the female rat. This modulatory effect is thought to be responsible for the observed effects of estradiol on motivated behaviors. Dopamine acting in the nucleus accumbens is thought to be important for the attribution of incentive motivational properties to cues that predict reward delivery, while dopamine in the striatum is associated with the expression of repetitive or stereotyped behaviors. Elevated concentrations of estradiol are associated with increased motivation for sex or cues associated with access to a mate, while simultaneously attenuating motivation for food. This shift in motivational salience is important for adaptive choice behavior in the natural environment. Additionally, estradiol's adaptive effects on motivation can be maladaptive when increasing motivation for non-natural reinforcers, such as drugs of abuse. Here we discuss the effect of estradiol on mesotelencephalic dopamine transmission and subsequent effects on motivated behaviors.

  17. Dopamine-imprinted monolithic column for capillary electrochromatography.

    PubMed

    Aşır, Süleyman; Sarı, Duygu; Derazshamshir, Ali; Yılmaz, Fatma; Şarkaya, Koray; Denizli, Adil

    2017-11-01

    A dopamine-imprinted monolithic column was prepared and used in capillary electrochromatography as stationary phase for the first time. Dopamine was selectively separated from aqueous solution containing the competitor molecule norepinephrine, which is similar in size and shape to the template molecule. Morphology of the dopamine-imprinted column was observed by scanning electron microscopy. The influence of the organic solvent content of mobile phase, applied pressure and pH of the mobile phase on the recognition of dopamine by the imprinted monolithic column has been evaluated, and the imprinting effect in the dopamine-imprinted monolithic polymer was verified. Developed dopamine-imprinted monolithic column resulted in excellent separation of dopamine from structurally related competitor molecule, norepinephrine. Separation was achieved in a short period of 10 min, with the electrophoretic mobility of 5.81 × 10 -5  m 2 V -1 s -1 at pH 5.0 and 500 mbar pressure. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. beta-Phenylethylamine modulates acetylcholine release in the rat striatum: involvement of a dopamine D(2) receptor mechanism.

    PubMed

    Kato, M; Ishida, K; Chuma, T; Abe, K; Shigenaga, T; Taguchi, K; Miyatake, T

    2001-04-20

    We examined the effects of beta-phenylethylamine on striatal acetylcholine release in freely moving rats using in vivo microdialysis. beta-Phenylethylamine at 12.5 mg/kg, i.p. did not affect acetylcholine release in the striatum, whereas 25 and 50 mg/kg, i.p. immediately induced an increase in acetylcholine release in the striatum at 15-45 min. This increase following intraperitoneal administration of beta-phenylethylamine (25 mg/kg) was not affected by locally applied SCH-23390 (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine, 10 microM), a dopamine D(1) receptor antagonist, nor by raclopride (10 microM), a dopamine D(2) receptor antagonist. The increased release of acetylcholine induced by beta-phenylethylamine was suppressed by local infusion of tetrodotoxin (1 microM). In contrast, the extracellular acetylcholine level in the striatum was significantly decreased by local application of beta-phenylethylamine (10 and 100 microM) in the striatum via a microdialysis probe. The decrease was completely blocked by local co-application of raclopride (10 microM). The beta-phenylethylamine-induced decrease in striatal acetylcholine release was not affected by co-perfusion with SCH-23390 (10 microM). These results indicate that systemic administration of beta-phenylethylamine increases acetylcholine release, whereas locally applied beta-phenylethylamine decreases striatal acetylcholine release in freely moving rats. Furthermore, the dopaminergic system, through the dopamine D(2) receptor, is involved in the locally applied beta-phenylethylamine-induced decrease in acetylcholine in the striatum.

  19. Pramipexole enhances disadvantageous decision-making: Lack of relation to changes in phasic dopamine release.

    PubMed

    Pes, Romina; Godar, Sean C; Fox, Andrew T; Burgeno, Lauren M; Strathman, Hunter J; Jarmolowicz, David P; Devoto, Paola; Levant, Beth; Phillips, Paul E; Fowler, Stephen C; Bortolato, Marco

    2017-03-01

    Pramipexole (PPX) is a high-affinity D 2 -like dopamine receptor agonist, used in the treatment of Parkinson's disease (PD) and restless leg syndrome. Recent evidence indicates that PPX increases the risk of problem gambling and impulse-control disorders in vulnerable patients. Although the molecular bases of these complications remain unclear, several authors have theorized that PPX may increase risk propensity by activating presynaptic dopamine receptors in the mesolimbic system, resulting in the reduction of dopamine release in the nucleus accumbens (NAcc). To test this possibility, we subjected rats to a probability-discounting task specifically designed to capture the response to disadvantageous options. PPX enhanced disadvantageous decision-making at a dose (0.3 mg/kg/day, SC) that reduced phasic dopamine release in the NAcc. To test whether these modifications in dopamine efflux were responsible for the observed neuroeconomic deficits, PPX was administered in combination with the monoamine-depleting agent reserpine (RES), at a low dose (1 mg/kg/day, SC) that did not affect baseline locomotor and operant responses. Contrary to our predictions, RES surprisingly exacerbated the effects of PPX on disadvantageous decision-making, even though it failed to augment PPX-induced decreases in phasic dopamine release. These results collectively suggest that PPX impairs the discounting of probabilistic losses and that the enhancement in risk-taking behaviors secondary to this drug may be dissociated from dynamic changes in mesolimbic dopamine release. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Cortical cholinergic deficiency enhances amphetamine-induced dopamine release in the accumbens but not striatum.

    PubMed

    Mattsson, Anna; Olson, Lars; Svensson, Torgny H; Schilström, Björn

    2007-11-01

    Cholinergic dysfunction has been implicated as a putative contributing factor in the pathogenesis of schizophrenia. Recently, we showed that cholinergic denervation of the neocortex in adult rats leads to a marked increase in the behavioral response to amphetamine. The main objective of this study was to investigate if the enhanced locomotor response to amphetamine seen after cortical cholinergic denervation was paralleled by an increased amphetamine-induced release of dopamine in the nucleus accumbens and/or striatum. The corticopetal cholinergic projections were lesioned by intraparenchymal infusion of 192 IgG-saporin into the nucleus basalis magnocellularis of adult rats. Amphetamine-induced dopamine release in the nucleus accumbens or striatum was monitored by in vivo microdialysis 2 to 3 weeks after lesioning. We found that cholinergic denervation of the rat neocortex leads to a significantly increased amphetamine-induced dopamine release in the nucleus accumbens. Interestingly, the cholinergic lesion did not affect amphetamine-induced release of dopamine in the striatum. The enhanced amphetamine-induced dopamine release in the nucleus accumbens in the cholinergically denervated rats could be reversed by administration of the muscarinic agonist oxotremorine, but not nicotine, prior to the amphetamine challenge, suggesting that loss of muscarinic receptor stimulation is likely to have caused the observed effect. The results suggest that abnormal responsiveness of dopamine neurons can be secondary to cortical cholinergic deficiency. This, in turn, might be of relevance for the pathophysiology of schizophrenia and provides a possible link between cholinergic disturbances and alteration of dopamine transmission.

  1. Dopamine and serotonin signaling during two sensitive developmental periods differentially impact adult aggressive and affective behaviors in mice.

    PubMed

    Yu, Q; Teixeira, C M; Mahadevia, D; Huang, Y; Balsam, D; Mann, J J; Gingrich, J A; Ansorge, M S

    2014-06-01

    Pharmacologic blockade of monoamine oxidase A (MAOA) or serotonin transporter (5-HTT) has antidepressant and anxiolytic efficacy in adulthood. Yet, genetically conferred MAOA or 5-HTT hypoactivity is associated with altered aggression and increased anxiety/depression. Here we test the hypothesis that increased monoamine signaling during development causes these paradoxical aggressive and affective phenotypes. We find that pharmacologic MAOA blockade during early postnatal development (P2-P21) but not during peri-adolescence (P22-41) increases anxiety- and depression-like behavior in adult (>P90) mice, mimicking the effect of P2-21 5-HTT inhibition. Moreover, MAOA blockade during peri-adolescence, but not P2-21 or P182-201, increases adult aggressive behavior, and 5-HTT blockade from P22-P41 reduced adult aggression. Blockade of the dopamine transporter, but not the norepinephrine transporter, during P22-41 also increases adult aggressive behavior. Thus, P2-21 is a sensitive period during which 5-HT modulates adult anxiety/depression-like behavior, and P22-41 is a sensitive period during which DA and 5-HT bi-directionally modulate adult aggression. Permanently altered DAergic function as a consequence of increased P22-P41 monoamine signaling might underlie altered aggression. In support of this hypothesis, we find altered aggression correlating positively with locomotor response to amphetamine challenge in adulthood. Proving that altered DA function and aggression are causally linked, we demonstrate that optogenetic activation of VTA DAergic neurons increases aggression. It therefore appears that genetic and pharmacologic factors impacting dopamine and serotonin signaling during sensitive developmental periods can modulate adult monoaminergic function and thereby alter risk for aggressive and emotional dysfunction.

  2. A novel iron (II) preferring dopamine agonist chelator D-607 significantly suppresses α-syn- and MPTP-induced toxicities in vivo.

    PubMed

    Das, Banibrata; Rajagopalan, Subramanian; Joshi, Gnanada S; Xu, Liping; Luo, Dan; Andersen, Julie K; Todi, Sokol V; Dutta, Aloke K

    2017-09-01

    Here, we report the characterization of a novel hybrid D 2 /D 3 agonist and iron (II) specific chelator, D-607, as a multi-target-directed ligand against Parkinson's disease (PD). In our previously published report, we showed that D-607 is a potent agonist of dopamine (DA) D 2 /D 3 receptors, exhibits efficacy in a reserpinized PD animal model and preferentially chelates to iron (II). As further evidence of its potential as a neuroprotective agent in PD, the present study reveals D-607 to be protective in neuronal PC12 cells against 6-OHDA toxicity. In an in vivo Drosophila melanogaster model expressing a disease-causing variant of α-synuclein (α-Syn) protein in fly eyes, the compound was found to significantly suppress toxicity compared to controls, concomitant with reduced levels of aggregated α-Syn. Furthermore, D-607 was able to rescue DAergic neurons from MPTP toxicity in mice, a well-known PD neurotoxicity model, following both sub-chronic and chronic MPTP administration. Mechanistic studies indicated that possible protection of mitochondria, up-regulation of hypoxia-inducible factor, reduction in formation of α-Syn aggregates and antioxidant activity may underlie the observed neuroprotection effects. These observations strongly suggest that D-607 has potential as a promising multifunctional lead molecule for viable symptomatic and disease-modifying therapy for PD. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Diffusion Kurtosis Imaging Detects Microstructural Alterations in Brain of α-Synuclein Overexpressing Transgenic Mouse Model of Parkinson's Disease: A Pilot Study.

    PubMed

    Khairnar, Amit; Latta, Peter; Drazanova, Eva; Ruda-Kucerova, Jana; Szabó, Nikoletta; Arab, Anas; Hutter-Paier, Birgit; Havas, Daniel; Windisch, Manfred; Sulcova, Alexandra; Starcuk, Zenon; Rektorova, Irena

    2015-11-01

    Evidence suggests that accumulation and aggregation of α-synuclein contribute to the pathogenesis of Parkinson's disease (PD). The aim of this study was to evaluate whether diffusion kurtosis imaging (DKI) will provide a sensitive tool for differentiating between α-synuclein-overexpressing transgenic mouse model of PD (TNWT-61) and wild-type (WT) littermates. This experiment was designed as a proof-of-concept study and forms a part of a complex protocol and ongoing translational research. Nine-month-old TNWT-61 mice and age-matched WT littermates underwent behavioral tests to monitor motor impairment and MRI scanning using 9.4 Tesla system in vivo. Tract-based spatial statistics (TBSS) and the DKI protocol were used to compare the whole brain white matter of TNWT-61 and WT mice. In addition, region of interest (ROI) analysis was performed in gray matter regions such as substantia nigra, striatum, hippocampus, sensorimotor cortex, and thalamus known to show higher accumulation of α-synuclein. For the ROI analysis, both DKI (6 b-values) protocol and conventional (2 b-values) diffusion tensor imaging (cDTI) protocol were used. TNWT-61 mice showed significant impairment of motor coordination. With the DKI protocol, mean, axial, and radial kurtosis were found to be significantly elevated, whereas mean and radial diffusivity were decreased in the TNWT-61 group compared to that in the WT controls with both TBSS and ROI analysis. With the cDTI protocol, the ROI analysis showed decrease in all diffusivity parameters in TNWT-61 mice. The current study provides evidence that DKI by providing both kurtosis and diffusivity parameters gives unique information that is complementary to cDTI for in vivo detection of pathological changes that underlie PD-like symptomatology in TNWT-61 mouse model of PD. This result is a crucial step in search for a candidate diagnostic biomarker with translational potential and relevance for human studies.

  4. Opponency Revisited: Competition and Cooperation Between Dopamine and Serotonin

    PubMed Central

    Boureau, Y-Lan; Dayan, Peter

    2011-01-01

    Affective valence lies on a spectrum ranging from punishment to reward. The coding of such spectra in the brain almost always involves opponency between pairs of systems or structures. There is ample evidence for the role of dopamine in the appetitive half of this spectrum, but little agreement about the existence, nature, or role of putative aversive opponents such as serotonin. In this review, we consider the structure of opponency in terms of previous biases about the nature of the decision problems that animals face, the conflicts that may thus arise between Pavlovian and instrumental responses, and an additional spectrum joining invigoration to inhibition. We use this analysis to shed light on aspects of the role of serotonin and its interactions with dopamine. PMID:20881948

  5. Dopamine, Affordance and Active Inference

    PubMed Central

    Friston, Karl J.; Shiner, Tamara; FitzGerald, Thomas; Galea, Joseph M.; Adams, Rick; Brown, Harriet; Dolan, Raymond J.; Moran, Rosalyn; Stephan, Klaas Enno; Bestmann, Sven

    2012-01-01

    The role of dopamine in behaviour and decision-making is often cast in terms of reinforcement learning and optimal decision theory. Here, we present an alternative view that frames the physiology of dopamine in terms of Bayes-optimal behaviour. In this account, dopamine controls the precision or salience of (external or internal) cues that engender action. In other words, dopamine balances bottom-up sensory information and top-down prior beliefs when making hierarchical inferences (predictions) about cues that have affordance. In this paper, we focus on the consequences of changing tonic levels of dopamine firing using simulations of cued sequential movements. Crucially, the predictions driving movements are based upon a hierarchical generative model that infers the context in which movements are made. This means that we can confuse agents by changing the context (order) in which cues are presented. These simulations provide a (Bayes-optimal) model of contextual uncertainty and set switching that can be quantified in terms of behavioural and electrophysiological responses. Furthermore, one can simulate dopaminergic lesions (by changing the precision of prediction errors) to produce pathological behaviours that are reminiscent of those seen in neurological disorders such as Parkinson's disease. We use these simulations to demonstrate how a single functional role for dopamine at the synaptic level can manifest in different ways at the behavioural level. PMID:22241972

  6. Striatal dopamine D1 and D2 receptors: widespread influences on methamphetamine-induced dopamine and serotonin neurotoxicity.

    PubMed

    Gross, Noah B; Duncker, Patrick C; Marshall, John F

    2011-11-01

    Methamphetamine (mAMPH) is an addictive psychostimulant drug that releases monoamines through nonexocytotic mechanisms. In animals, binge mAMPH dosing regimens deplete markers for monoamine nerve terminals, for example, dopamine and serotonin transporters (DAT and SERT), in striatum and cerebral cortex. Although the precise mechanism of mAMPH-induced damage to monoaminergic nerve terminals is uncertain, both dopamine D1 and D2 receptors are known to be important. Systemic administration of dopamine D1 or D2 receptor antagonists to rodents prevents mAMPH-induced damage to striatal dopamine nerve terminals. Because these studies employed systemic antagonist administration, the specific brain regions involved remain to be elucidated. The present study examined the contribution of dopamine D1 and D2 receptors in striatum to mAMPH-induced DAT and SERT neurotoxicities. In this experiment, either the dopamine D1 antagonist, SCH23390, or the dopamine D2 receptor antagonist, sulpiride, was intrastriatally infused during a binge mAMPH regimen. Striatal DAT and cortical, hippocampal, and amygdalar SERT were assessed as markers of mAMPH-induced neurotoxicity 1 week following binge mAMPH administration. Blockade of striatal dopamine D1 or D2 receptors during an otherwise neurotoxic binge mAMPH regimen produced widespread protection against mAMPH-induced striatal DAT loss and cortical, hippocampal, and amygdalar SERT loss. This study demonstrates that (1) dopamine D1 and D2 receptors in striatum, like nigral D1 receptors, are needed for mAMPH-induced striatal DAT reductions, (2) these same receptors are needed for mAMPH-induced SERT loss, and (3) these widespread influences of striatal dopamine receptor antagonists are likely attributable to circuits connecting basal ganglia to thalamus and cortex. Copyright © 2011 Wiley-Liss, Inc.

  7. In vitro and in vivo evaluation of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate)/dopamine-coated electrodes for dopamine delivery.

    PubMed

    Sui, L; Song, X J; Ren, J; Cai, W J; Ju, L H; Wang, Y; Wang, L Y; Chen, M

    2014-06-01

    Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrene sulfonate) (PSS) has a variety of chemical and biomedical applications. The application of PEDOT/PSS polymers in drug delivery has attracted attention. However, whether conducting polymers of PEDOT/PSS could be used for dopamine delivery has not clear. In the present study, the PEDOT/PSS coatings incorporated with dopamine were fabricated on 0.5 mm diameter platinum electrodes, electrochemical properties, and dopamine delivery capacities of these electrodes were evaluated in vitro and in vivo through implanting these electrodes into brain striatum area. The findings demonstrated that the PEDOT/PSS/dopamine coatings on platinum electrodes could reduce electrodes impedances, increase charge storage capacities, and release significant levels of dopamine upon electrical stimulation of these electrodes. These results indicated that polymers of PEDOT/PSS/dopamine could be used for dopamine delivery, implicating potential application of PEDOT/PSS/dopamine-coated implantable electrodes in the treatment of some diseases associated with dopamine deficits, such as, electrodes for the treatment of Parkinson's disease during deep brain stimulation. Copyright © 2013 Wiley Periodicals, Inc.

  8. Continuous cerebroventricular administration of dopamine: A new treatment for severe dyskinesia in Parkinson's disease?

    PubMed

    Laloux, C; Gouel, F; Lachaud, C; Timmerman, K; Do Van, B; Jonneaux, A; Petrault, M; Garcon, G; Rouaix, N; Moreau, C; Bordet, R; Duce, J A; Devedjian, J C; Devos, D

    2017-07-01

    In Parkinson's disease (PD) depletion of dopamine in the nigro-striatal pathway is a main pathological hallmark that requires continuous and focal restoration. Current predominant treatment with intermittent oral administration of its precursor, Levodopa (l-dopa), remains the gold standard but pharmacological drawbacks trigger motor fluctuations and dyskinesia. Continuous intracerebroventricular (i.c.v.) administration of dopamine previously failed as a therapy because of an inability to resolve the accelerated dopamine oxidation and tachyphylaxia. We aim to overcome prior challenges by demonstrating treatment feasibility and efficacy of continuous i.c.v. of dopamine close to the striatum. Dopamine prepared either anaerobically (A-dopamine) or aerobically (O-dopamine) in the presence or absence of a conservator (sodium metabisulfite, SMBS) was assessed upon acute MPTP and chronic 6-OHDA lesioning and compared to peripheral l-dopa treatment. A-dopamine restored motor function and induced a dose dependent increase of nigro-striatal tyrosine hydroxylase positive neurons in mice after 7days of MPTP insult that was not evident with either O-dopamine or l-dopa. In the 6-OHDA rat model, continuous circadian i.c.v. injection of A-dopamine over 30days also improved motor activity without occurrence of tachyphylaxia. This safety profile was highly favorable as A-dopamine did not induce dyskinesia or behavioral sensitization as observed with peripheral l-dopa treatment. Indicative of a new therapeutic strategy for patients suffering from l-dopa related complications with dyskinesia, continuous i.c.v. of A-dopamine has greater efficacy in mediating motor impairment over a large therapeutic index without inducing dyskinesia and tachyphylaxia. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Hydrophobic-Interaction-Induced Stiffening of α -Synuclein Fibril Networks

    NASA Astrophysics Data System (ADS)

    Semerdzhiev, Slav A.; Lindhoud, Saskia; Stefanovic, Anja; Subramaniam, Vinod; van der Schoot, Paul; Claessens, Mireille M. A. E.

    2018-05-01

    In water, networks of semiflexible fibrils of the protein α -synuclein stiffen significantly with increasing temperature. We make plausible that this reversible stiffening is a result of hydrophobic contacts between the fibrils that become more prominent with increasing temperature. The good agreement of our experimentally observed temperature dependence of the storage modulus of the network with a scaling theory linking network elasticity with reversible cross-linking enables us to quantify the endothermic binding enthalpy and estimate the effective size of hydrophobic patches on the fibril surface. Our findings may not only shed light on the role of amyloid deposits in disease conditions, but can also inspire new approaches for the design of thermoresponsive materials.

  10. Hydrophobic-Interaction-Induced Stiffening of α-Synuclein Fibril Networks.

    PubMed

    Semerdzhiev, Slav A; Lindhoud, Saskia; Stefanovic, Anja; Subramaniam, Vinod; van der Schoot, Paul; Claessens, Mireille M A E

    2018-05-18

    In water, networks of semiflexible fibrils of the protein α-synuclein stiffen significantly with increasing temperature. We make plausible that this reversible stiffening is a result of hydrophobic contacts between the fibrils that become more prominent with increasing temperature. The good agreement of our experimentally observed temperature dependence of the storage modulus of the network with a scaling theory linking network elasticity with reversible cross-linking enables us to quantify the endothermic binding enthalpy and estimate the effective size of hydrophobic patches on the fibril surface. Our findings may not only shed light on the role of amyloid deposits in disease conditions, but can also inspire new approaches for the design of thermoresponsive materials.

  11. Dopamine and anorexia nervosa.

    PubMed

    Södersten, P; Bergh, C; Leon, M; Zandian, M

    2016-01-01

    We have suggested that reduced food intake increases the risk for anorexia nervosa by engaging mesolimbic dopamine neurons, thereby initially rewarding dieting. Recent fMRI studies have confirmed that dopamine neurons are activated in anorexia nervosa, but it is not clear whether this response is due to the disorder or to its resulting nutritional deficit. When the body senses the shortage of nutrients, it rapidly shifts behavior toward foraging for food as a normal physiological response and the mesolimbic dopamine neurons may be involved in that process. On the other hand, the altered dopamine status of anorexics has been suggested to result from a brain abnormality that underlies their complex emotional disorder. We suggest that the outcomes of the treatments that emerge from that perspective remain poor because they target the mental symptoms that are actually the consequences of the food deprivation that accompanies anorexia. On the other hand, a method that normalizes the disordered eating behavior of anorexics results in much better physiological, behavioral, and emotional outcomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Interactions between aromatase (estrogen synthase) and dopamine in the control of male sexual behavior in quail.

    PubMed

    Balthazart, Jacques; Baillien, Michelle; Ball, Gregory F

    2002-05-01

    In male quail, like in other vertebrates including rodents, testosterone acting especially through its estrogenic metabolites is necessary for the activation of male sexual behavior. Also, the administration of dopamine agonists and antagonists profoundly influences male sexual behavior. How the steroid-sensitive neural network and dopamine interact physiologically, remains largely unknown. It is often implicitly assumed that testosterone or its metabolite estradiol, stimulates male sexual behavior via the modification of dopaminergic transmission. We have now identified in quail two possible ways in which dopamine could potentially affect sexual behavior by modulating the aromatization of testosterone into an estrogen. One is a long-acting mechanism that presumably involves the modification of dopaminergic transmission followed by the alteration of the genomic expression of aromatase. The other is a more rapid mechanism that does not appear to be dopamine receptor-mediated and may involve a direct interaction of dopamine with aromatase (possibly via substrate competition). We review here the experimental data supporting the existence of these controls of aromatase activity by dopamine and discuss the possible contribution of these controls to the activation of male sexual behavior.

  13. Association of Cerebrospinal Fluid β-Amyloid 1-42, T-tau, P-tau181, and α-Synuclein Levels With Clinical Features of Drug-Naive Patients With Early Parkinson Disease

    PubMed Central

    Kang, Ju-Hee; Irwin, David J.; Chen-Plotkin, Alice S.; Siderowf, Andrew; Caspell, Chelsea; Coffey, Christopher S.; Waligórska, Teresa; Taylor, Peggy; Pan, Sarah; Frasier, Mark; Marek, Kenneth; Kieburtz, Karl; Jennings, Danna; Simuni, Tanya; Tanner, Caroline M.; Singleton, Andrew; Toga, Arthur W.; Chowdhury, Sohini; Mollenhauer, Brit; Trojanowski, John Q.; Shaw, Leslie M.

    2014-01-01

    Importance We observed a significant correlation between cerebrospinal fluid (CSF) levels of tau proteins and α-synuclein, but not β-amyloid 1–42 (Aβ1–42), and lower concentration of CSF biomarkers, as compared with healthy controls, in a cohort of entirely untreated patients with Parkinson disease (PD) at the earliest stage of the disease studied so far. Objective To evaluate the baseline characteristics and relationship to clinical features of CSF biomarkers (Aβ1–42, total tau [T-tau], tau phosphorylated at threonine 181 [P-tau181], and α-synuclein) in drug-naive patients with early PD and demographically matched healthy controls enrolled in the Parkinson’s Progression Markers Initiative (PPMI) study. Design, Setting, and Participants Cross-sectional study of the initial 102 research volunteers (63 patients with PD and 39 healthy controls) of the PPMI cohort. Main Outcomes and Measures The CSF biomarkers were measured by INNO-BIA AlzBio3 immunoassay (Aβ1–42, T-tau, and P-tau181; Innogenetics Inc) or by enzyme-linked immunosorbent assay (α-synuclein). Clinical features including diagnosis, demographic characteristics, motor, neuropsychiatric, and cognitive assessments, and DaTscan were systematically assessed according to the PPMI study protocol. Results Slightly, but significantly, lower levels of Aβ1–42, T-tau, P-tau181, α-synuclein, and T-tau/Aβ1–42 were seen in subjects with PD compared with healthy controls but with a marked overlap between groups. Using multivariate regression analysis, we found that lower Aβ1–42 and P-tau181 levels were associated with PD diagnosis and that decreased CSF T-tau and α-synuclein were associated with increased motor severity. Notably, when we classified patients with PD by their motor phenotypes, lower CSF Aβ1–42 and P-tau181 concentrations were associated with the postural instability–gait disturbance–dominant phenotype but not with the tremor-dominant or intermediate phenotype. Finally, we

  14. Subchronic, Low-Level Intraperitoneal Injections of Manganese (IV) Oxide and Manganese (II) Chloride Affect Rat Brain Neurochemistry.

    PubMed

    Nielsen, Brian S; Larsen, Erik H; Ladefoged, Ole; Lam, Henrik R

    Manganese (Mn) is neurotoxic and can induce manganism, a Parkinson-like disease categorized as being a serious central nervous system irreversible neurodegenerative disease. An increased risk of developing symptoms of Parkinson disease has been linked to work-related exposure, for example, for workers in agriculture, horticulture, and people living near areas with frequent use of Mn-containing pesticides. In this study, the focus was placed on neurochemical effects of Mn. Rats were dosed intraperitoneally with 0.9% NaCl (control), 1.22 mg Mn (as MnO 2 )/kg bodyweight (bw)/day, or 2.5 mg Mn (as MnCl 2 )/kg bw/day for 7 d/wk for 8 or 12 weeks. This dosing regimen adds relevant new knowledge about Mn neurotoxicity as a consequence of low-dose subchronic Mn dosing. Manganese concentrations increased in the striatum, the rest of the brain, and in plasma, and regional brain neurotransmitter concentrations, including noradrenaline, dopamine (DA), 5-hydroxytrytamine, glutamate, taurine, and γ-amino butyric acid, and the activity of acetylcholinesterase changed. Importantly, a target parameter for Parkinson disease and manganism, the striatal DA concentration, was reduced after 12 weeks of dosing with MnCl 2 . Plasma prolactin concentration was not significantly affected due to a potentially reduced dopaminergic inhibition of the prolactin release from the anterior hypophysis. No effects on the striatal α-synuclein and synaptophysin protein levels were detected.

  15. PRESYNAPTIC DOPAMINE MODULATION BY STIMULANT SELF ADMINISTRATION

    PubMed Central

    España, Rodrigo A.; Jones, Sara R.

    2013-01-01

    The mesolimbic dopamine system is an essential participant in the initiation and modulation of various forms of goal-directed behavior, including drug reinforcement and addiction processes. Dopamine neurotransmission is increased by acute administration of all drugs of abuse, including the stimulants cocaine and amphetamine. Chronic exposure to these drugs via voluntary self-administration provides a model of stimulant abuse that is useful in evaluating potential behavioral and neurochemical adaptations that occur during addiction. This review describes commonly used methodologies to measure dopamine and baseline parameters of presynaptic dopamine regulation, including exocytotic release and reuptake through the dopamine transporter in the nucleus accumbens core, as well as dramatic adaptations in dopamine neurotransmission and drug sensitivity that occur with acute non-contingent and chronic, contingent self-administration of cocaine and amphetamine. PMID:23277050

  16. Alterations in striatal dopamine catabolism precede loss of substantia nigra neurons in a mouse model of Juvenile Neuronal Ceroid Lipofuscinosis

    PubMed Central

    Weimer, Jill M.; Benedict, Jared W.; Elshatory, Yasser M.; Short, Douglas W.; Ramirez-Montealegre, Denia; Ryan, Deborah A.; Alexander, Noreen A.; Federoff, Howard J.; Cooper, Jonathan D.; Pearce, David A.

    2016-01-01

    Batten disease, or juvenile neuronal ceroid lipofuscinosis (JNCL), results from mutations in the CLN3 gene. This disorder presents clinically around the age of five years with visual deficits progressing to include seizures, cognitive impairment, motor deterioration, hallucinations, and premature death by the third to forth decade of life. The motor deficits include coordination and gait abnormalities, myoclonic jerks, inability to initiate movements, and spasticity. Previous work from our laboratory has identified an early reduction in catechol-O-methyltransferase (COMT), an enzyme responsible for the efficient degradation of dopamine. Alterations in the kinetics of dopamine metabolism could cause the accumulation of undegraded or unsequestered dopamine leading to the formation of toxic dopamine intermediates. We report an imbalance in the catabolism of dopamine in three month Cln3-/- mice persisting through nine months of age that may be causal to oxidative damage within the striatum at nine months of age. Combined with the previously reported inflammatory changes and loss of post-synaptic D1α receptors, this could facilitate cell loss in striatal projection regions and underlie a general locomotion deficit that becomes apparent at twelve months of age in Cln3-/- mice. This study provides evidence for early changes in the kinetics of COMT in the Cln3-/- mouse striatum, affecting the turnover of dopamine, likely leading to neuron loss and motor deficits. These data provide novel insights into the basis of motor deficits in JNCL and how alterations in dopamine catabolism may result in oxidative damage and localized neuronal loss in this disorder. PMID:17617387

  17. Dopamine D1 and D2 Receptor Immunoreactivities in the Arcuate-Median Eminence Complex and their Link to the Tubero-Infundibular Dopamine Neurons

    PubMed Central

    Romero-Fernandez, W.; Borroto-Escuela, D.O.; Vargas-Barroso, V.; Narváez, M.; Di Palma, M.; Agnati, L.F.; Sahd, J. Larriva

    2014-01-01

    Dopamine D1 and D2 receptor immunohistochemistry and Golgi techniques were used to study the structure of the adult rat arcuate-median eminence complex, and determine the distribution of the dopamine D1 and D2 receptor immunoreactivities therein, particularly in relation to the tubero-infundibular dopamine neurons. Punctate dopamine D1 and D2 receptor immunoreactivities, likely located on nerve terminals, were enriched in the lateral palisade zone built up of nerve terminals, while the densities were low to modest in the medial palisade zone. A codistribution of dopamine D1 receptor or dopamine D2 receptor immunoreactive puncta with tyrosine hydroxylase immunoreactive nerve terminals was demonstrated in the external layer. Dopamine D1 receptor but not dopamine D2 receptor immnunoreactivites nerve cell bodies were found in the ventromedial part of the arcuate nucleus and in the lateral part of the internal layer of the median eminence forming a continuous cell mass presumably representing neuropeptide Y immunoreactive nerve cell bodies. The major arcuate dopamine/ tyrosine hydroxylase nerve cell group was found in the dorsomedial part. A large number of tyrosine hydroxylase immunoreactive nerve cell bodies in this region demonstrated punctate dopamine D1 receptor immunoreactivity but only a few presented dopamine D2 receptor immunoreactivity which were mainly found in a substantial number of tyrosine hydroxylase cell bodies of the ventral periventricular hypothalamic nucleus, also belonging to the tuberoinfundibular dopamine neurons. Structural evidence for projections of the arcuate nerve cells into the median eminence was also obtained. Distal axons formed horizontal axons in the internal layer issuing a variable number of collaterals classified into single or multiple strands located in the external layer increasing our understanding of the dopamine nerve terminal networks in this region. Dopamine D1 and D2 receptors may therefore directly and differentially

  18. Dopamine D1 and D2 receptor immunoreactivities in the arcuate-median eminence complex and their link to the tubero-infundibular dopamine neurons.

    PubMed

    Romero-Fernandez, W; Borroto-Escuela, D O; Vargas-Barroso, V; Narváez, M; Di Palma, M; Agnati, L F; Larriva Sahd, J; Fuxe, K

    2014-07-18

    Dopamine D1 and D2 receptor immunohistochemistry and Golgi techniques were used to study the structure of the adult rat arcuate-median eminence complex, and determine the distribution of the dopamine D1 and D2 receptor immunoreactivities therein, particularly in relation to the tubero-infundibular dopamine neurons. Punctate dopamine D1 and D2 receptor immunoreactivities, likely located on nerve terminals, were enriched in the lateral palisade zone built up of nerve terminals, while the densities were low to modest in the medial palisade zone. A codistribution of dopamine D1 receptor or dopamine D2 receptor immunoreactive puncta with tyrosine hydroxylase immunoreactive nerve terminals was demonstrated in the external layer. Dopamine D1 receptor but not dopamine D2 receptor immnunoreactivites nerve cell bodies were found in the ventromedial part of the arcuate nucleus and in the lateral part of the internal layer of the median eminence forming a continuous cell mass presumably representing neuropeptide Y immunoreactive nerve cell bodies. The major arcuate dopamine/ tyrosine hydroxylase nerve cell group was found in the dorsomedial part. A large number of tyrosine hydroxylase immunoreactive nerve cell bodies in this region demonstrated punctate dopamine D1 receptor immunoreactivity but only a few presented dopamine D2 receptor immunoreactivity which were mainly found in a substantial number of tyrosine hydroxylase cell bodies of the ventral periventricular hypothalamic nucleus, also belonging to the tubero-infundibular dopamine neurons. Structural evidence for projections of the arcuate nerve cells into the median eminence was also obtained. Distal axons formed horizontal axons in the internal layer issuing a variable number of collaterals classified into single or multiple strands located in the external layer increasing our understanding of the dopamine nerve terminal networks in this region.  Dopamine D1 and D2 receptors may therefore directly and differentially

  19. Novel AAV-based rat model of forebrain synucleinopathy shows extensive pathologies and progressive loss of cholinergic interneurons.

    PubMed

    Aldrin-Kirk, Patrick; Davidsson, Marcus; Holmqvist, Staffan; Li, Jia-Yi; Björklund, Tomas

    2014-01-01

    Synucleinopathies, characterized by intracellular aggregation of α-synuclein protein, share a number of features in pathology and disease progression. However, the vulnerable cell population differs significantly between the disorders, despite being caused by the same protein. While the vulnerability of dopamine cells in the substantia nigra to α-synuclein over-expression, and its link to Parkinson's disease, is well studied, animal models recapitulating the cortical degeneration in dementia with Lewy-bodies (DLB) are much less mature. The aim of this study was to develop a first rat model of widespread progressive synucleinopathy throughout the forebrain using adeno-associated viral (AAV) vector mediated gene delivery. Through bilateral injection of an AAV6 vector expressing human wild-type α-synuclein into the forebrain of neonatal rats, we were able to achieve widespread, robust α-synuclein expression with preferential expression in the frontal cortex. These animals displayed a progressive emergence of hyper-locomotion and dysregulated response to the dopaminergic agonist apomorphine. The animals receiving the α-synuclein vector displayed significant α-synuclein pathology including intra-cellular inclusion bodies, axonal pathology and elevated levels of phosphorylated α-synuclein, accompanied by significant loss of cortical neurons and a progressive reduction in both cortical and striatal ChAT positive interneurons. Furthermore, we found evidence of α-synuclein sequestered by IBA-1 positive microglia, which was coupled with a distinct change in morphology. In areas of most prominent pathology, the total α-synuclein levels were increased to, on average, two-fold, which is similar to the levels observed in patients with SNCA gene triplication, associated with cortical Lewy body pathology. This study provides a novel rat model of progressive cortical synucleinopathy, showing for the first time that cholinergic interneurons are vulnerable to α-synuclein

  20. [Dopamine receptor signaling regulates human osteoclastogenesis].

    PubMed

    Hanami, Kentaro; Nakano, Kazuhisa; Tanaka, Yoshiya

    2013-01-01

    Although the central nervous system and the neurotransmitters are known to control not only the immune system but also the homeostasis of bone mass, their pathological relevance to bone disorders remains unclear. Osteoclasts in the synovium of rheumatoid arthritis (RA) play an important role in bone destruction. It is known that increased sympathetic nervous activity increases both differentiation and function of osteoclasts, which leads to bone loss. Dopamine, a major neurotransmitter, transmits signals via five different seven-transmembrane G protein-coupled receptors termed D1 to D5. We previously reported that dopamine plays an important role in IL-6-IL-17 axis and subsequent joint destruction in RA. The major source of dopamine in the synovial tissue of RA was dendritic cells (DCs) that stored and secreted dopamine. Dopamine released by DCs bounded to D1-like dopamine receptors on T cells and induced activation of cAMP and differentiation to Th17 cells via IL-6 production We here overview the interplay among the immune system, bone metabolism and neurologic system shedding light upon dopaminergic signals upon osteoclastogenesis.

  1. Dopamine synapse is a neuroligin-2–mediated contact between dopaminergic presynaptic and GABAergic postsynaptic structures

    PubMed Central

    Uchigashima, Motokazu; Ohtsuka, Toshihisa; Kobayashi, Kazuto; Watanabe, Masahiko

    2016-01-01

    Midbrain dopamine neurons project densely to the striatum and form so-called dopamine synapses on medium spiny neurons (MSNs), principal neurons in the striatum. Because dopamine receptors are widely expressed away from dopamine synapses, it remains unclear how dopamine synapses are involved in dopaminergic transmission. Here we demonstrate that dopamine synapses are contacts formed between dopaminergic presynaptic and GABAergic postsynaptic structures. The presynaptic structure expressed tyrosine hydroxylase, vesicular monoamine transporter-2, and plasmalemmal dopamine transporter, which are essential for dopamine synthesis, vesicular filling, and recycling, but was below the detection threshold for molecules involving GABA synthesis and vesicular filling or for GABA itself. In contrast, the postsynaptic structure of dopamine synapses expressed GABAergic molecules, including postsynaptic adhesion molecule neuroligin-2, postsynaptic scaffolding molecule gephyrin, and GABAA receptor α1, without any specific clustering of dopamine receptors. Of these, neuroligin-2 promoted presynaptic differentiation in axons of midbrain dopamine neurons and striatal GABAergic neurons in culture. After neuroligin-2 knockdown in the striatum, a significant decrease of dopamine synapses coupled with a reciprocal increase of GABAergic synapses was observed on MSN dendrites. This finding suggests that neuroligin-2 controls striatal synapse formation by giving competitive advantage to heterologous dopamine synapses over conventional GABAergic synapses. Considering that MSN dendrites are preferential targets of dopamine synapses and express high levels of dopamine receptors, dopamine synapse formation may serve to increase the specificity and potency of dopaminergic modulation of striatal outputs by anchoring dopamine release sites to dopamine-sensing targets. PMID:27035941

  2. The attachment of α -synuclein to a fiber: A coarse-grain approach

    NASA Astrophysics Data System (ADS)

    Ilie, Ioana M.; den Otter, Wouter K.; Briels, Wim J.

    2017-03-01

    We present simulations of the amyloidogenic core of α-synuclein, the protein causing Parkinson's disease, as a short chain of coarse-grain patchy particles. Each particle represents a sequence of about a dozen amino acids. The fluctuating secondary structure of this intrinsically disordered protein is modelled by dynamic variations of the shape and interaction characteristics of the patchy particles, ranging from spherical with weak isotropic attractions for the disordered state to spherocylindrical with strong directional interactions for a β-sheet. Flexible linkers between the particles enable sampling of the tertiary structure. This novel model is applied here to study the growth of an amyloid fibril, by calculating the free energy profile of a protein attaching to the end of a fibril. The simulation results suggest that the attaching protein readily becomes trapped in a mis-folded state, thereby inhibiting further growth of the fibril until the protein has readjusted to conform to the fibril structure, in line with experimental findings and previous simulations on small fragments of other proteins.

  3. Cholinergic Interneurons Underlie Spontaneous Dopamine Release in Nucleus Accumbens

    PubMed Central

    2017-01-01

    The release of dopamine from terminals in the NAc is regulated by a number of factors, including voltage-gated ion channels, D2-autoreceptors, and nAChRs. Cholinergic interneurons (CINs) drive dopamine release through activation of nAChRs on dopamine terminals. Using cyclic voltammetry in mouse brain slices, nAChR-dependent spontaneous dopamine transients and the mechanisms underlying the origin were examined in the NAc. Spontaneous events were infrequent (0.3 per minute), but the rate and amplitude were increased after blocking Kv channels with 4-aminopyridine. Although the firing frequency of CINs was increased by blocking glutamate reuptake with TBOA and the Sk blocker apamin, only 4-aminopyridine increased the frequency of dopamine transients. In contrast, inhibition of CIN firing with the μ/δ selective opioid [Met5]enkephalin (1 μm) decreased spontaneous dopamine transients. Cocaine increased the rate and amplitude of dopamine transients, suggesting that the activity of the dopamine transporter limits the detection of these events. In the presence of cocaine, the rate of spontaneous dopamine transients was further increased after blocking D2-autoreceptors. Blockade of muscarinic receptors had no effect on evoked dopamine release, suggesting that feedback inhibition of acetylcholine release was not involved. Thus, although spontaneous dopamine transients are reliant on nAChRs, the frequency was not strictly governed by the activity of CINs. The increase in frequency of spontaneous dopamine transients induced by cocaine was not due to an increase in cholinergic tone and is likely a product of an increase in detection resulting from decreased dopamine reuptake. SIGNIFICANCE STATEMENT The actions of dopamine in the NAc are thought to be responsible for endogenous reward and the reinforcing properties of drugs of abuse, such as psychostimulants. The present work examines the mechanisms underlying nAChR-induced spontaneous dopamine release. This study

  4. The Neurobiological Basis of Cognitive Impairment in Parkinson'S Disease

    PubMed Central

    Halliday, Glenda M.; Leverenz, James B.; Schneider, Jay S.; Adler, Charles H.

    2014-01-01

    The recent formalization of clinical criteria for PD with dementia (PD-D) codifies many studies on this topic, including those assessing biological correlates. These studies show that the emergence of PD-D occurs on the background of severe dopamine deficits with the main pathological drivers of cognitive decline being a synergistic effect between α -synuclein and Alzheimer's disease pathology. The presence of these pathologies correlates with a marked loss of limbic and cortically projecting dopamine, noradrenaline, serotonin and acetylcholine neurons, although the exact timing of these relationships remains to be determined. Genetic factors, such as triplications in the α-synuclein gene, lead to a clear increased risk of PD-D, while others, such as parkin mutations, are associated with a reduced risk of PD-D. The very recent formalization of clinical criteria for PD with mild cognitive impairment (PD-MCI) allows only speculation on its biological and genetic bases. Critical assessment of animal models shows that chronic low dose MPTP treatment in primates recapitulates PD-MCI over time, enhancing the current biological concept of PD-MCI as having enhanced dopamine deficiency in frontostriatal pathways as well as involvement of other neurotransmitter systems. Data from other animal models support multiple transmitter involvement in cognitive impairment in PD. While dopamine dysfunction has been highlighted because of its obvious role in PD, the role of the other neurotransmitter systems, neurodegenerative pathologies and genetic factors in PD-MCI remain to be fully elucidated. PMID:24757112

  5. Drug Targets from Genetics: Alpha-Synuclein

    PubMed Central

    Danzer, Karin M.; McLean, Pamela J.

    2012-01-01

    One of the critical issues in Parkinson disease (PD) research is the identity of the specific toxic, pathogenic moiety. In PD, mutations in alpha-synuclein (αsyn) or multiplication of the SNCA gene encoding αsyn, result in a phenotype of cellular inclusions, cell death, and brain dysfunction. While the historical point of view has been that the macroscopic aggregates containing αsyn are the toxic species, in the last several years evidence has emerged that suggests instead that smaller soluble species - likely oligomers containing misfolded αsyn - are actually the toxic moiety and that the fibrillar inclusions may even be a cellular detoxification pathway and less harmful. If soluble misfolded species of αsyn are the toxic moieties, then cellular mechanisms that degrade misfolded αsyn would be neuroprotective and a rational target for drug development. In this review we will discuss the fundamental mechanisms underlying αsyn toxicity including oligomer formation, oxidative stress, and degradation pathways and consider rational therapeutic strategies that may have the potential to prevent or halt αsyn induced pathogenesis in PD. PMID:21838671

  6. Dopamine neurons in culture express VGLUT2 explaining their capacity to release glutamate at synapses in addition to dopamine.

    PubMed

    Dal Bo, Gregory; St-Gelais, Fannie; Danik, Marc; Williams, Sylvain; Cotton, Mathieu; Trudeau, Louis-Eric

    2004-03-01

    Dopamine neurons have been suggested to use glutamate as a cotransmitter. To identify the basis of such a phenotype, we have examined the expression of the three recently identified vesicular glutamate transporters (VGLUT1-3) in postnatal rat dopamine neurons in culture. We found that the majority of isolated dopamine neurons express VGLUT2, but not VGLUT1 or 3. In comparison, serotonin neurons express only VGLUT3. Single-cell RT-PCR experiments confirmed the presence of VGLUT2 mRNA in dopamine neurons. Arguing for phenotypic heterogeneity among axon terminals, we find that only a proportion of terminals established by dopamine neurons are VGLUT2-positive. Taken together, our results provide a basis for the ability of dopamine neurons to release glutamate as a cotransmitter. A detailed analysis of the conditions under which DA neurons gain or loose a glutamatergic phenotype may provide novel insight into pathophysiological processes that underlie diseases such as schizophrenia, Parkinson's disease and drug dependence.

  7. Novel animal model defines genetic contributions for neuron-to-neuron transfer of α-synuclein.

    PubMed

    Tyson, Trevor; Senchuk, Megan; Cooper, Jason F; George, Sonia; Van Raamsdonk, Jeremy M; Brundin, Patrik

    2017-08-08

    Cell-to-cell spreading of misfolded α-synuclein (α-syn) is suggested to contribute to the progression of neuropathology in Parkinson's disease (PD). Compelling evidence supports the hypothesis that misfolded α-syn transmits from neuron-to-neuron and seeds aggregation of the protein in the recipient cells. Furthermore, α-syn frequently appears to propagate in the brains of PD patients following a stereotypic pattern consistent with progressive spreading along anatomical pathways. We have generated a C. elegans model that mirrors this progression and allows us to monitor α-syn neuron-to-neuron transmission in a live animal over its lifespan. We found that modulation of autophagy or exo/endocytosis, affects α-syn transfer. Furthermore, we demonstrate that silencing C. elegans orthologs of PD-related genes also increases the accumulation of α-syn. This novel worm model is ideal for screening molecules and genes to identify those that modulate prion-like spreading of α-syn in order to target novel strategies for disease modification in PD and other synucleinopathies.

  8. Reduction of dopamine D2/3 receptor binding in the striatum after a single administration of esketamine, but not R-ketamine: a PET study in conscious monkeys.

    PubMed

    Hashimoto, Kenji; Kakiuchi, Takeharu; Ohba, Hiroyuki; Nishiyama, Shingo; Tsukada, Hideo

    2017-03-01

    R-ketamine appears to be a potent, long-lasting and safer antidepressant, relative to esketamine (S-ketamine), since it might be free of psychotomimetic side effects. Using [ 11 C]raclopride and positron emission tomography (PET), we investigated whether esketamine and R-ketamine can affect dopamine D 2/3 receptor binding in the conscious monkey brain. A single infusion of esketamine (0.5 mg/kg), but not R-ketamine (0.5 mg/kg), caused a reduction of binding availability of dopamine D 2/3 receptor in the monkey striatum. This study suggests that unlike to R-ketamine, esketamine can cause dopamine release in the striatum, and that its release might be associated with psychotomimetic effects of esketamine.

  9. Elevated Striatal Dopamine Function in Immigrants and Their Children: A Risk Mechanism for Psychosis.

    PubMed

    Egerton, Alice; Howes, Oliver D; Houle, Sylvain; McKenzie, Kwame; Valmaggia, Lucia R; Bagby, Michael R; Tseng, Huai-Hsuan; Bloomfield, Michael A P; Kenk, Miran; Bhattacharyya, Sagnik; Suridjan, Ivonne; Chaddock, Chistopher A; Winton-Brown, Toby T; Allen, Paul; Rusjan, Pablo; Remington, Gary; Meyer-Lindenberg, Andreas; McGuire, Philip K; Mizrahi, Romina

    2017-03-01

    Migration is a major risk factor for schizophrenia but the neurochemical processes involved are unknown. One candidate mechanism is through elevations in striatal dopamine synthesis and release. The objective of this research was to determine whether striatal dopamine function is elevated in immigrants compared to nonimmigrants and the relationship with psychosis. Two complementary case-control studies of in vivo dopamine function (stress-induced dopamine release and dopamine synthesis capacity) in immigrants compared to nonimmigrants were performed in Canada and the United Kingdom. The Canadian dopamine release study included 25 immigrant and 31 nonmigrant Canadians. These groups included 23 clinical high risk (CHR) subjects, 9 antipsychotic naïve patients with schizophrenia, and 24 healthy volunteers. The UK dopamine synthesis study included 32 immigrants and 44 nonimmigrant British. These groups included 50 CHR subjects and 26 healthy volunteers. Both striatal stress-induced dopamine release and dopamine synthesis capacity were significantly elevated in immigrants compared to nonimmigrants, independent of clinical status. These data provide the first evidence that the effect of migration on the risk of developing psychosis may be mediated by an elevation in brain dopamine function. © The Author 2017. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.

  10. Dopamine alters glutamate receptor desensitization in retinal horizontal cells of the perch (Perca fluviatilis).

    PubMed Central

    Schmidt, K F; Kruse, M; Hatt, H

    1994-01-01

    The patch-clamp technique in combination with a fast liquid filament application system was used to study the effect of dopamine on the glutamate receptor desensitization in horizontal cells of the perch (Perca fluviatilis). Kinetics of ligand-gated ion channels in fish horizontal cells are modulated by dopamine. This modulation is presumably mediated by a cAMP-dependent protein phosphorylation. Before incubation with dopamine, the glutamate receptors of horizontal cells activate and desensitize with fast time constants. In the whole-cell recording mode, fast application of the agonists L-glutamate, quisqualate, or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid prior to the dopamine incubation gives rise to fast transient currents with peak values of about 200 pA that desensitize within 100 ms. Kainate as agonist produced higher steady-state currents but no transient currents. After incubation of the cells with dopamine for 3 min, the desensitization was significantly reduced and the agonists L-glutamate, quisqualate, or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid induced steady-state currents with amplitudes that were similar to the previously observed transient currents. Kainate-induced currents were only slightly affected. Fast desensitizing currents upon fast application of L-glutamate were also recorded from outside-out patches that were excised from horizontal cells before incubation with dopamine. The currents from excised patches desensitized to a steady-state level of about 0.2 of the peak amplitude with time constants of less than 2 ms. When the outside-out patches were excised from cells after dopamine incubation, steady-state currents were enhanced and no transient currents were observed. The results may indicate that the dopamine-dependent modulation of glutamate-induced currents, which is presumably mediated by a protein phosphorylation, is due to an alteration of the desensitization of the glutamate receptors. PMID:7520178

  11. Antidepressants differentially affect striatal amphetamine-stimulated dopamine and serotonin release in rats with high and low novelty-oriented behaviour.

    PubMed

    O'Leary, Aet; Kõiv, Kadri; Raudkivi, Karita; Harro, Jaanus

    2016-11-01

    In the studies of depression pathogenesis and antidepressant action, the monoaminergic hypothesis of depression has mainly focused on the serotonergic and noradrenergic mechanisms. However, dopaminergic neurotransmission is also linked to both depressive symptomatology as well as antidepressant effects. We have previously shown that persistent inter-individual differences in the rat behavioural activity in novel environments is associated with differences in the striatal extracellular levels of dopamine and serotonin, depressive-like behaviour and the expression of several depression-related genes. The aim of the current study was to investigate the relative potency of the tricyclic antidepressant imipramine, the selective serotonin re-uptake inhibitor fluoxetine, and the selective noradrenaline re-uptake inhibitor reboxetine (all drugs administered in the dose of 10mg/kg, i.p.) to enhance amphetamine-stimulated dopamine and serotonin release in the striatum using in vivo microdialysis in awake, freely-moving rats, categorized into high explorers (HE) and low explorers (LE) based on their spontaneous novelty-oriented behaviour. The basal extracellular dopamine and serotonin concentration in the striatum did not differ between the LE- and HE-rats. None of the antidepressants alone were able to modify baseline striatal dopamine levels, but the amphetamine-stimulated dopamine release was significantly higher in the HE-rats after acute and chronic imipramine (but not fluoxetine or reboxetine). Acute imipramine and fluoxetine, but not reboxetine, increased both the basal and amphetamine-stimulated levels of serotonin in the striatum. Again, the HE-rats had higher amphetamine-stimulated serotonin release after fluoxetine administration. These findings suggest that rats with depressive-like phenotype are less sensitive to the neurochemical effects of antidepressants in the striatum. These results may have relevance in understanding the neurobiological bases for inter

  12. Dopamine depletion attenuates some behavioral abnormalities in a hyperdopaminergic mouse model of bipolar disorder

    PubMed Central

    van Enkhuizen, Jordy; Geyer, Mark A.; Halberstadt, Adam L.; Zhuang, Xiaoxi; Young, Jared W.

    2014-01-01

    Background Patients with BD suffer from multifaceted symptoms, including hyperactive and psychomotor agitated behaviors. Previously, we quantified hyperactivity, increased exploration, and straighter movements of patients with BD mania in the human Behavioral Pattern Monitor (BPM). A similar BPM profile is observed in mice that are hyperdopaminergic due to reduced dopamine transporter (DAT) functioning. We hypothesized that dopamine depletion through alpha-methyl-p-tyrosine (AMPT) administration would attenuate this mania-like profile. Methods Male and female DAT wild-type (WT; n=26) and knockdown (KD; n=28) mice on a C57BL/6 background were repeatedly tested in the BPM to assess profile robustness and stability. The optimal AMPT dose was identified by treating male C57BL/6 mice (n=39) with vehicle or AMPT (10, 30, or 100 mg/kg) at 24, 20, and 4 h prior to testing in the BPM. Then, male and female DAT WT (n=40) and KD (n=37) mice were tested in the BPM after vehicle or AMPT (30 mg/kg) treatment. Results Compared to WT littermates, KD mice exhibited increased activity, exploration, straighter movement, and disorganized behavior. AMPT-treatment reduced hyperactivity and increased path organization, but potentiated specific exploration in KD mice without affecting WT mice. Limitations AMPT is not specific to dopamine and also depletes norepinephrine. Conclusions KD mice exhibit abnormal exploration in the BPM similar to patients with BD mania. AMPT-induced dopamine depletion attenuated some, but potentiated other, aspects of this mania-like profile in mice. Future studies should extend these findings into other aspects of mania to determine the suitability of AMPT as a treatment for BD mania. PMID:24287168

  13. Central GLP-1 receptor activation modulates cocaine-evoked phasic dopamine signaling in the nucleus accumbens core.

    PubMed

    Fortin, Samantha M; Roitman, Mitchell F

    2017-07-01

    Drugs of abuse increase the frequency and magnitude of brief (1-3s), high concentration (phasic) dopamine release events in terminal regions. These are thought to be a critical part of drug reinforcement and ultimately the development of addiction. Recently, metabolic regulatory peptides, including the satiety signal glucagon-like peptide-1 (GLP-1), have been shown to modulate cocaine reward-driven behavior and sustained dopamine levels after cocaine administration. Here, we use fast-scan cyclic voltammetry (FSCV) to explore GLP-1 receptor (GLP-1R) modulation of dynamic dopamine release in the nucleus accumbens (NAc) during cocaine administration. We analyzed dopamine release events in both the NAc shell and core, as these two subregions are differentially affected by cocaine and uniquely contribute to motivated behavior. We found that central delivery of the GLP-1R agonist Exendin-4 suppressed the induction of phasic dopamine release events by intravenous cocaine. This effect was selective for dopamine signaling in the NAc core. Suppression of phasic signaling in the core by Exendin-4 could not be attributed to interference with cocaine binding to one of its major substrates, the dopamine transporter, as cocaine-induced increases in reuptake were unaffected. The results suggest that GLP-1R activation, instead, exerts its suppressive effects by altering dopamine release - possibly by suppressing the excitability of dopamine neurons. Given the role of NAc core dopamine in the generation of conditioned responses based on associative learning, suppression of cocaine-induced dopamine signaling in this subregion by GLP-1R agonism may decrease the reinforcing properties of cocaine. Thus, GLP-1Rs remain viable targets for the treatment and prevention of cocaine seeking, taking and relapse. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Enhanced dopamine D2 autoreceptor function in the adult prefrontal cortex contributes to dopamine hypoactivity following adolescent social stress.

    PubMed

    Weber, Matthew A; Graack, Eric T; Scholl, Jamie L; Renner, Kenneth J; Forster, Gina L; Watt, Michael J

    2018-06-14

    Adult psychiatric disorders characterized by cognitive deficits reliant on prefrontal cortex (PFC) dopamine are promoted by teenage bullying. Similarly, male Sprague-Dawley rats exposed to social defeat in mid-adolescence (P35-39) show impaired working memory in adulthood (P56-70), along with decreased medial PFC (mPFC) dopamine activity that results in part from increased dopamine transporter-mediated clearance. Here, we determined if dopamine synthesis and D2 autoreceptor-mediated inhibition of dopamine release in the adult mPFC are also enhanced by adolescent defeat to contribute to later dopamine hypofunction. Control and previously defeated rats did not differ in either DOPA accumulation following amino acid decarboxylase inhibition (NSD-1015 100 mg/kg ip.) or total/phosphorylated tyrosine hydroxylase protein expression, suggesting dopamine synthesis in the adult mPFC is not altered by adolescent defeat. However, exposure to adolescent defeat caused greater decreases in extracellular dopamine release (measured using in vivo chronoamperometry) in the adult mPFC upon local infusion of the D2 receptor agonist quinpirole (3 nM), implying greater D2 autoreceptor function. Equally enhanced D2 autoreceptor-mediated inhibition of dopamine release is seen in the adolescent (P40 or P49) mPFC, which declines in control rats by adulthood. However, this developmental decrease in autoreceptor function is absent following adolescent defeat, suggesting retention of an adolescent-like phenotype into adulthood. Current and previous findings indicate adolescent defeat decreases extracellular dopamine availability in the adult mPFC via both enhanced inhibition of dopamine release and increased dopamine clearance, which may be viable targets for improving treatment of cognitive deficits seen in neuropsychiatric disorders promoted by adolescent stress. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  15. β-Phenylethylamine requires the dopamine transporter to increase extracellular dopamine in Caenorhabditis elegans dopaminergic neurons.

    PubMed

    Hossain, Murad; Wickramasekara, Rochelle N; Carvelli, Lucia

    2014-07-01

    β-Phenylethylamine (βPEA) is an endogenous amine that has been shown to increase the synaptic levels of dopamine (DA). A number of in vitro and behavioral studies suggest the dopamine transporter (DAT) plays a role in the effects generated by βPEA, however the mechanism through which βPEA affects DAT has not yet been elucidated. Here, we used Caenorhabditis (C.) elegans DAT (DAT-1) expressing LLC-pk1 cells and neuronal cultures to investigate whether the βPEA-induced increase of extracellular DA required DAT-1. Our data show that βPEA increases extracellular dopamine both in DAT-1 transfected cells and cultures of differentiated neurons. RTI-55, a cocaine homologue and DAT inhibitor, completely blocked the βPEA-induced effect in transfected cells. However in neuronal cultures, RTI-55 only partly inhibited the increase of extracellular DA generated by βPEA. These results suggest that βPEA requires DAT-1 and other, not yet identified proteins, to increase extracellular DA when tested in a native system. Furthermore, our results suggest that βPEA-induced increase of extracellular DA does not require functional monoamine vesicles as genetic ablation of the C. elegans homologue vesicular monoamine transporter, cat-1, did not compromise the ability of βPEA to increase extracellular DA. Finally, our electrophysiology data show that βPEA caused fast-rising and self-inactivating amperometric currents in a subset of wild-type DA neurons but not in neurons isolated from dat-1 knockout animals. Taken together, these data demonstrate that in both DA neurons and heterogeneous cultures of differentiated C. elegans neurons, βPEA releases cytoplasmic DA through DAT-1 to ultimately increase the extracellular concentration of DA. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. β-phenylethylamine Requires the Dopamine Transporter to Increase Extracellular Dopamine in C. elegans Dopaminergic Neurons

    PubMed Central

    Hossain, Murad; Wickramasekara, Rochelle N.; Carvelli, Lucia

    2013-01-01

    β-phenylethylamine (βPEA) is an endogenous amine that has been shown to increase the synaptic levels of dopamine (DA). A number of in vitro and behavioral studies suggest the dopamine transporter (DAT) plays a role in the effects generated by βPEA, however the mechanism through which βPEA affects DAT has not yet been elucidated. Here, we used Caenorhabditis (C.) elegans DAT (DAT-1) expressing LLC-pk1 cells and neuronal cultures to investigate whether the βPEA-induced increase of extracellular DA required DAT-1. Our data show that βPEA increases extracellular dopamine both in DAT-1 transfected cells and cultures of differentiated neurons. RTI-55, a cocaine homologue and DAT inhibitor, completely blocked the βPEA-induced effect in transfected cells. However in neuronal cultures, RTI-55 only partly inhibited the increase of extracellular DA generated by βPEA. These results suggest that βPEA requires DAT-1 and other, not yet identified proteins, to increase extracellular DA when tested in a native system. Furthermore, our results suggest that βPEA-induced increase of extracellular DA does not require functional monoamine vesicles as genetic ablation of the C. elegans homologue vesicular monoamine transporter, cat-1, did not compromise the ability of βPEA to increase extracellular DA. Finally, our electrophysiology data show that βPEA caused fast-rising and self-inactivating amperometric currents in a subset of wild-type DA neurons but not in neurons isolated from dat-1 knockout animals. Taken together, these data demonstrate that in both DA neurons and heterogeneous cultures of differentiated C. elegans neurons, βPEA releases cytoplasmic DA through DAT-1 to ultimately increase the extracellular concentration of DA. PMID:24161617

  17. Aggressive behavior, related conduct problems, and variation in genes affecting dopamine turnover.

    PubMed

    Grigorenko, Elena L; De Young, Colin G; Eastman, Maria; Getchell, Marya; Haeffel, Gerald J; Klinteberg, Britt af; Koposov, Roman A; Oreland, Lars; Pakstis, Andrew J; Ponomarev, Oleg A; Ruchkin, Vladislav V; Singh, Jay P; Yrigollen, Carolyn M

    2010-01-01

    A number of dopamine-related genes have been implicated in the etiology of violent behavior and conduct problems. Of these genes, the ones that code for the enzymes that influence the turnover of dopamine (DA) have received the most attention. In this study, we investigated 12 genetic polymorphisms in four genes involved with DA functioning (COMT, MAOA and MAOB, and DbetaH) in 179 incarcerated male Russian adolescents and two groups of matched controls: boys without criminal records referred to by their teachers as (a) "troubled-behavior-free" boys, n=182; and (b) "troubled-behavior" boys, n=60. The participants were classified as (1) being incarcerated or not, (2) having the DSM-IV diagnosis of conduct disorder (CD) or not, and (3) having committed violent or nonviolent crimes (for the incarcerated individuals only). The findings indicate that, although no single genetic variant in any of the four genes differentiated individuals in the investigated groups, various linear combinations (i.e., haplotypes) and nonlinear combinations (i.e., interactions between variants within and across genes) of genetic variants resulted in informative and robust classifications for two of the three groupings. These combinations of genetic variants differentiated individuals in incarceration vs. nonincarcerated and CD vs. no-CD groups; no informative combinations were established consistently for the grouping by crime within the incarcerated individuals. This study underscores the importance of considering multiple rather than single markers within candidate genes and their additive and interactive combinations, both with themselves and with nongenetic indicators, while attempting to understand the genetic background of such complex behaviors as serious conduct problems. (c) 2010 Wiley-Liss, Inc.

  18. Effect of psilocin on extracellular dopamine and serotonin levels in the mesoaccumbens and mesocortical pathway in awake rats.

    PubMed

    Sakashita, Yuichi; Abe, Kenji; Katagiri, Nobuyuki; Kambe, Toshie; Saitoh, Toshiaki; Utsunomiya, Iku; Horiguchi, Yoshie; Taguchi, Kyoji

    2015-01-01

    Psilocin (3-[2-(dimethylamino)ethyl]-1H-indol-4-ol) is a hallucinogenic component of the Mexican mushroom Psilocybe mexicana and a skeletal serotonin (5-HT) analogue. Psilocin is the active metabolite of psilocybin (3-[2-(dimethylamino)ethyl]-1H-indol-4-yl dihydrogen phosphate). In the present study, we examined the effects of systemically administered psilocin on extracellular dopamine and 5-HT concentrations in the ventral tegmental area (VTA), nucleus accumbens, and medial prefrontal cortex of the dopaminergic pathway in awake rats using in vivo microdialysis. Intraperitoneal administration of psilocin (5, 10 mg/kg) significantly increased extracellular dopamine levels in the nucleus accumbens. Psilocin did not affect the extracellular 5-HT level in the nucleus accumbens. Conversely, systemic administration of psilocin (10 mg/kg) significantly increased extracellular 5-HT levels in the medial prefrontal cortex of rats, but dopamine was decreased in this region. However, neither extracellular dopamine nor 5-HT levels in the VTA were altered by administration of psilocin. Behaviorally, psilocin significantly increased the number of head twitches. Thus, psilocin affects the dopaminergic system in the nucleus accumbens. In the serotonergic system, psilocin contribute to a crucial effect in the medial prefrontal cortex. The present data suggest that psilocin increased both the extracellular dopamine and 5-HT concentrations in the mesoaccumbens and/or mesocortical pathway.

  19. Targeting the Progression of Parkinson’s Disease

    PubMed Central

    George, J.L; Mok, S; Moses, D; Wilkins, S; Bush, A.I; Cherny, R.A; Finkelstein, D.I

    2009-01-01

    By the time a patient first presents with symptoms of Parkinson’s disease at the clinic, a significant proportion (50-70%) of the cells in the substantia nigra (SN) has already been destroyed. This degeneration progresses until, within a few years, most of the cells have died. Except for rare cases of familial PD, the initial trigger for cell loss is unknown. However, we do have some clues as to why the damage, once initiated, progresses unabated. It would represent a major advance in therapy to arrest cell loss at the stage when the patient first presents at the clinic. Current therapies for Parkinson’s disease focus on relieving the motor symptoms of the disease, these unfortunately lose their effectiveness as the neurodegeneration and symptoms progress. Many experimental approaches are currently being investigated attempting to alter the progression of the disease. These range from replacement of the lost neurons to neuroprotective therapies; each of these will be briefly discussed in this review. The main thrust of this review is to explore the interactions between dopamine, alpha synuclein and redox-active metals. There is abundant evidence suggesting that destruction of SN cells occurs as a result of a self-propagating series of reactions involving dopamine, alpha synuclein and redox-active metals. A potent reducing agent, the neurotransmitter dopamine has a central role in this scheme, acting through redox metallo-chemistry to catalyze the formation of toxic oligomers of alpha-synuclein and neurotoxic metabolites including 6-hydroxydopamine. It has been hypothesized that these feed the cycle of neurodegeneration by generating further oxidative stress. The goal of dissecting and understanding the observed pathological changes is to identify therapeutic targets to mitigate the progression of this debilitating disease. PMID:19721815

  20. Potential of mean force and molecular dynamics study on the transient interactions between α and β synuclein that drive inhibition of α-synuclein aggregation.

    PubMed

    Sanjeev, Airy; Sahu, Ravi Kumar; Mattaparthi, Venkata Satish Kumar

    2017-11-01

    Self-association of α-synuclein (αS) into pathogenic oligomeric species and subsequent formation of highly ordered amyloid fibrils is linked to the Parkinson's disease. So most of the recent studies are now focused on the development of potential therapeutic strategies against this debilitating disease. β-synuclein (βS), a presynaptic protein that co-localizes with αS has been recently reported to act as an inhibitor of αS self-assembly. But the specificity of molecular interaction, nature and location between αS/βS is not known despite the potential importance of βS as an inhibitor of αS. We used molecular dynamics and potential of mean force (PMF) to study association of αS/βS and αS/αS. The calculated PMF indicates that contact wells are significantly deeper and presence of a minimum at αS/βS separation of 13.5 Å with a free energy barrier of 40 kcal/mol. We observed the dissociation energy barrier to be two times higher for the hetero-dimer (αS/βS) than the homo-dimer (αS/αS). We also carried out umbrella samplings involving two degrees of freedom (one being the distance between the monomeric units and the other angle between the long axes of the two monomeric chains) and observed similar PMF profile. We noticed relatively stronger range of transient interactions between the monomeric units in hetero-dimer (αS/βS) than homo-dimer (αS/αS). So our findings suggest that αS readily combines with βS to form hetero-dimer than combining with itself in forming homo-dimer. Hence we see predominant transient interactions between αS and βS can be used to drive inhibition of αS aggregation.

  1. Opiate anti-nociception is attenuated following lesion of large dopamine neurons of the periaqueductal grey: critical role for D1 (not D2) dopamine receptors.

    PubMed

    Flores, Juan A; El Banoua, Fadwa; Galán-Rodríguez, Beatriz; Fernandez-Espejo, Emilio

    2004-07-01

    The periaqueductal grey (PAG) area is involved in pain modulation as well as in opiate-induced anti-nociceptive effects. The PAG possess dopamine neurons, and it is likely that this dopaminergic network participates in anti-nociception. The objective was to further study the morphology of the PAG dopaminergic network, along with its role in nociception and opiate-induced analgesia in rats, following either dopamine depletion with the toxin 6-hydroxydopamine or local injection of dopaminergic antagonists. Nociceptive responses were studied through the tail-immersion (spinal reflex) and the hot-plate tests (integrated supraspinal response), establishing a cut-off time to further minimize animal suffering. Heroin and morphine were employed as opiates. Histological data indicated that the dopaminergic network of the PAG is composed of two types of neurons: small rounded cells, and large multipolar neurons. Following dopamine depletion of the PAG, large neurons (not small ones) were selectively affected by the toxin (61.9% dopamine cell loss, 80.7% reduction of in vitro dopaminergic peak), and opiate-induced analgesia in the hot-plate test (not the tail-immersion test) was reliably attenuated in lesioned rats (P < 0.01). After infusions of dopaminergic ligands into the PAG, D(1) (not D(2)) receptor antagonism attenuated opiate-induced analgesia in a dose-dependent manner in the hot-plate test. The present study provides evidence that large neurons of the dopaminergic network of the PAG participate in supraspinal (not spinal) nociceptive responses after opiates through the involvement of D(1) dopamine receptors. This dopaminergic system should be included as another network within the PAG involved in opiate-induced anti-nociception.

  2. Lipopolysaccharide mitagates methamphetamine-induced striatal dopamine depletion via modulating local TNF-alpha and dopamine transporter expression.

    PubMed

    Lai, Yu-Ting; Tsai, Yen-Ping N; Cherng, Chianfang G; Ke, Jing-Jer; Ho, Ming-Che; Tsai, Chia-Wen; Yu, Lung

    2009-04-01

    Systemic lipopolysaccharide (LPS) treatment may affect methamphetamine (MA)-induced nigrostriatal dopamine (DA) depletion. This study was undertaken to determine the critical time window for the protective effects of LPS treatment and the underlying mechanisms. An LPS injection (1 mg/kg) 72 h before or 2 h after MA treatment [three consecutive, subcutaneous injections of MA (10 mg/kg each) at 2-h intervals] diminished the MA-induced DA depletion in mouse striatum. Such an LPS-associated effect was independent of MA-produced hyperthermia. TNF-alpha, IL-1beta, IL-6 expressions were all elevated in striatal tissues following a systemic injection with LPS, indicating that peripheral LPS treatment affected striatal pro-inflammatory cytokine expression. Striatal TNF-alpha expression was dramatically increased at 72 and 96 h after the MA treatment, while such TNF-alpha elevation was abolished by the LPS pretreatment protocol. Moreover, MA-produced activation of nuclear NFkappaB, a transcription factor following TNF-alpha activation, in striatum was abolished by the LPS (1 mg/kg) pretreatment. Furthermore, thalidomide, a TNF-alpha antagonist, treatment abolished the LPS pretreatment-associated protective effects. Pretreatment with mouse recombinant TNF-alpha in striatum diminished the MA-produced DA depletion. Finally, single LPS treatment caused a rapid down-regulation of dopamine transporter (DAT) in striatum. Taken together, we conclude that peripheral LPS treatment protects nigrostriatal DA neurons against MA-induced toxicity, in part, by reversing elevated TNF-alpha expression and subsequent signaling cascade and causing a rapid DAT down-regulation in striatum.

  3. Lesion of medial prefrontal dopamine terminals abolishes habituation of accumbens shell dopamine responsiveness to taste stimuli.

    PubMed

    Bimpisidis, Zisis; De Luca, Maria Antonietta; Pisanu, Augusta; Di Chiara, Gaetano

    2013-02-01

    Taste stimuli increase extracellular dopamine (DA) in the nucleus accumbens (NAc) and in the medial prefrontal cortex (mPFC). This effect shows single-trial habituation in NAc shell but not in core or in mPFC. Morphine sensitization abolishes habituation of DA responsiveness in NAc shell but induces it in mPFC. These observations support the hypothesis of an inhibitory influence of mPFC DA on NAc DA. To test this hypothesis, we used in vivo microdialysis to investigate the effect of mPFC 6-hydroxy-dopamine (6-OHDA) lesions on the NAc DA responsiveness to taste stimuli. 6-OHDA was infused bilaterally in the mPFC of rats implanted with guide cannulae. After 1 week, rats were implanted with an intraoral catheter, microdialysis probes were inserted into the guide cannulae, and dialysate DA was monitored in NAc shell/core after intraoral chocolate. 6-OHDA infusion reduced tissue DA in the mPFC by 75%. Tyrosine hydroxylase immunohistochemistry showed that lesions were confined to the mPFC. mPFC 6-OHDA lesion did not affect the NAc shell DA responsiveness to chocolate in naive rats but abolished habituation in rats pre-exposed to the taste. In the NAc core, mPFC lesion potentiated, delayed and prolonged the stimulatory DA response to taste but failed to affect DA in pre-exposed rats. Behavioural taste reactions and motor activity were not affected. The results indicate a top-down control of NAc DA by mPFC and a reciprocal relationship between DA transmission in these two areas. Moreover, habituation of DA responsiveness in the NAc shell is dependent upon an intact DA input to the mPFC. © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  4. Pleasurable music affects reinforcement learning according to the listener

    PubMed Central

    Gold, Benjamin P.; Frank, Michael J.; Bogert, Brigitte; Brattico, Elvira

    2013-01-01

    Mounting evidence links the enjoyment of music to brain areas implicated in emotion and the dopaminergic reward system. In particular, dopamine release in the ventral striatum seems to play a major role in the rewarding aspect of music listening. Striatal dopamine also influences reinforcement learning, such that subjects with greater dopamine efficacy learn better to approach rewards while those with lesser dopamine efficacy learn better to avoid punishments. In this study, we explored the practical implications of musical pleasure through its ability to facilitate reinforcement learning via non-pharmacological dopamine elicitation. Subjects from a wide variety of musical backgrounds chose a pleasurable and a neutral piece of music from an experimenter-compiled database, and then listened to one or both of these pieces (according to pseudo-random group assignment) as they performed a reinforcement learning task dependent on dopamine transmission. We assessed musical backgrounds as well as typical listening patterns with the new Helsinki Inventory of Music and Affective Behaviors (HIMAB), and separately investigated behavior for the training and test phases of the learning task. Subjects with more musical experience trained better with neutral music and tested better with pleasurable music, while those with less musical experience exhibited the opposite effect. HIMAB results regarding listening behaviors and subjective music ratings indicate that these effects arose from different listening styles: namely, more affective listening in non-musicians and more analytical listening in musicians. In conclusion, musical pleasure was able to influence task performance, and the shape of this effect depended on group and individual factors. These findings have implications in affective neuroscience, neuroaesthetics, learning, and music therapy. PMID:23970875

  5. A new arylalkylamine N-acetyltransferase in silkworm (Bombyx mori) affects integument pigmentation.

    PubMed

    Long, Yaohang; Li, Jiaorong; Zhao, Tianfu; Li, Guannan; Zhu, Yong

    2015-04-01

    Dopamine is a precursor for melanin synthesis. Arylalkylamine N-acetyltransferase (AANAT) is involved in the melatonin formation in insects because it could catalyze the transformation from dopamine to dopamine-N-acetyldopamine. In this study, we identified a new AANAT gene in the silkworm (Bombyx mori) and assessed its role in the silkworm. The cDNA of this gene encodes 233 amino acids that shares 57 % amino acid identity with the Bm-iAANAT protein. We thus refer to this gene as Bm-iAANAT2. To investigate the role of Bm-iAANAT2, we constructed a transgenic interference system using a 3xp3 promoter to suppress the expression of Bm-iAANAT2 in the silkworm. We observed that melanin deposition occurs in the head and integument in transgenic lines. To verify the melanism pattern, dopamine content and the enzyme activity of AANAT were determined by high-performance liquid chromatography (HPLC). We found that an increase in dopamine levels affects melanism patterns on the heads of transgenic B. mori. A reduction in the enzyme activity of AANAT leads to changes in dopamine levels. We analyzed the expression of the Bm-iAANAT2 genes by qPCR and found that the expression of Bm-iAANAT2 gene is significantly lower in transgenic lines. Our results lead us to conclude that Bm-iAANAT2 is a new arylalkylamine N-acetyltransferase gene in the silkworm and is involved in the metabolism of the dopamine to avoid the generation of melanin.

  6. α-Synuclein Mutation Inhibits Endocytosis at Mammalian Central Nerve Terminals.

    PubMed

    Xu, Jianhua; Wu, Xin-Sheng; Sheng, Jiansong; Zhang, Zhen; Yue, Hai-Yuan; Sun, Lixin; Sgobio, Carmelo; Lin, Xian; Peng, Shiyong; Jin, Yinghui; Gan, Lin; Cai, Huaibin; Wu, Ling-Gang

    2016-04-20

    α-Synuclein (α-syn) missense and multiplication mutations have been suggested to cause neurodegenerative diseases, including Parkinson's disease (PD) and dementia with Lewy bodies. Before causing the progressive neuronal loss, α-syn mutations impair exocytosis, which may contribute to eventual neurodegeneration. To understand how α-syn mutations impair exocytosis, we developed a mouse model that selectively expressed PD-related human α-syn A53T (h-α-synA53T) mutation at the calyx of Held terminals, where release mechanisms can be dissected with a patch-clamping technique. With capacitance measurement of endocytosis, we reported that h-α-synA53T, either expressed transgenically or dialyzed in the short term in calyces, inhibited two of the most common forms of endocytosis, the slow and rapid vesicle endocytosis at mammalian central synapses. The expression of h-α-synA53Tin calyces also inhibited vesicle replenishment to the readily releasable pool. These findings may help to understand how α-syn mutations impair neurotransmission before neurodegeneration. α-Synuclein (α-syn) missense or multiplication mutations may cause neurodegenerative diseases, such as Parkinson's disease and dementia with Lewy bodies. The initial impact of α-syn mutations before neuronal loss is impairment of exocytosis, which may contribute to eventual neurodegeneration. The mechanism underlying impairment of exocytosis is poorly understood. Here we report that an α-syn mutant, the human α-syn A53T, inhibited two of the most commonly observed forms of endocytosis, slow and rapid endocytosis, at a mammalian central synapse. We also found that α-syn A53T inhibited vesicle replenishment to the readily releasable pool. These results may contribute to accounting for the widely observed early synaptic impairment caused by α-syn mutations in the progression toward neurodegeneration. Copyright © 2016 the authors 0270-6474/16/364408-07$15.00/0.

  7. Stimulus-Dependent Dopamine Release in Attention-Deficit/Hyperactivity Disorder

    ERIC Educational Resources Information Center

    Sikstrom, Sverker; Soderlund, Goran

    2007-01-01

    Attention-deficit/hyperactivity disorder (ADHD) is related to an attenuated and dysfunctional dopamine system. Normally, a high extracellular dopamine level yields a tonic dopaminergic input that down-regulates stimuli-evoked phasic dopamine responses through autoreceptors. Abnormally low tonic extracellular dopamine in ADHD up-regulates the…

  8. Dopamine reward prediction error coding.

    PubMed

    Schultz, Wolfram

    2016-03-01

    Reward prediction errors consist of the differences between received and predicted rewards. They are crucial for basic forms of learning about rewards and make us strive for more rewards-an evolutionary beneficial trait. Most dopamine neurons in the midbrain of humans, monkeys, and rodents signal a reward prediction error; they are activated by more reward than predicted (positive prediction error), remain at baseline activity for fully predicted rewards, and show depressed activity with less reward than predicted (negative prediction error). The dopamine signal increases nonlinearly with reward value and codes formal economic utility. Drugs of addiction generate, hijack, and amplify the dopamine reward signal and induce exaggerated, uncontrolled dopamine effects on neuronal plasticity. The striatum, amygdala, and frontal cortex also show reward prediction error coding, but only in subpopulations of neurons. Thus, the important concept of reward prediction errors is implemented in neuronal hardware.

  9. Dopamine reward prediction error coding

    PubMed Central

    Schultz, Wolfram

    2016-01-01

    Reward prediction errors consist of the differences between received and predicted rewards. They are crucial for basic forms of learning about rewards and make us strive for more rewards—an evolutionary beneficial trait. Most dopamine neurons in the midbrain of humans, monkeys, and rodents signal a reward prediction error; they are activated by more reward than predicted (positive prediction error), remain at baseline activity for fully predicted rewards, and show depressed activity with less reward than predicted (negative prediction error). The dopamine signal increases nonlinearly with reward value and codes formal economic utility. Drugs of addiction generate, hijack, and amplify the dopamine reward signal and induce exaggerated, uncontrolled dopamine effects on neuronal plasticity. The striatum, amygdala, and frontal cortex also show reward prediction error coding, but only in subpopulations of neurons. Thus, the important concept of reward prediction errors is implemented in neuronal hardware. PMID:27069377

  10. Exposure to the Polybrominated Diphenyl Ether Mixture DE-71 Damages the Nigrostriatal Dopamine System: Role of Dopamine Handling in Neurotoxicity

    PubMed Central

    Bradner, Joshua M.; Suragh, Tiffany A.; Wilson, W. Wyatt; Lazo, Carlos R.; Stout, Kristen A.; Kim, Hye Mi; Wang, Min Z.; Walker, Douglas I.; Pennell, Kurt D.; Richardson, Jason R.; Miller, Gary W.; Caudle, W. Michael

    2013-01-01

    In the last several decades polybrominated diphenyl ethers (PBDEs) have replaced the previously banned polychlorinated biphenyls (PCBs) in multiple flame retardant utilities. As epidemiological and laboratory studies have suggested PCBs as a risk factor for Parkinson’s disease (PD), the similarities between PBDEs and PCBs suggest that PBDEs have the potential to be neurotoxic to the dopamine system. The purpose of this study was to evaluate the neurotoxic effects of the PBDE mixture, DE-71, on the nigrostriatal dopamine system and address the role of altered dopamine handling in mediating this neurotoxicity. Using an in vitro model system we found DE-71 effectively caused cell death in a dopaminergic cell line as well as reducing the number of TH+ neurons isolated from VMAT2 WT and LO animals. Assessment of DE-71 neurotoxicity in vivo demonstrated significant deposition of PBDE congeners in the brains of mice, leading to reductions in striatal dopamine and dopamine handling, as well as reductions in the striatal dopamine transporter (DAT) and VMAT2. Additionally, DE-71 elicited a significant locomotor deficit in the VMAT2 WT and LO mice. However, no change was seen in TH expression in dopamine terminal or in the number of dopamine neurons in the substantia nigra pars compacta (SNpc). To date, these are the first data to demonstrate that exposure to PBDEs disrupts the nigrostriatal dopamine system. Given their similarities to PCBs, additional laboratory and epidemiological research should be considered to assess PBDEs as a potential risk factor for PD and other neurological disorders. PMID:23287494

  11. Ventral tegmental ionotropic glutamate receptor stimulation of nucleus accumbens tonic dopamine efflux blunts hindbrain-evoked phasic neurotransmission: implications for dopamine dysregulation disorders.

    PubMed

    Tye, S J; Miller, A D; Blaha, C D

    2013-11-12

    Activation of glutamate receptors within the ventral tegmental area (VTA) stimulates extrasynaptic (basal) dopamine release in terminal regions, including the nucleus accumbens (NAc). Hindbrain inputs from the laterodorsal tegmental nucleus (LDT) are critical for elicitation of phasic VTA dopamine cell activity and consequent transient dopamine release. This study investigated the role of VTA ionotropic glutamate receptor (iGluR) stimulation on both basal and LDT electrical stimulation-evoked dopamine efflux in the NAc using in vivo chronoamperometry and fixed potential amperometry in combination with stearate-graphite paste and carbon fiber electrodes, respectively. Intra-VTA infusion of the iGluR agonists (±)-α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA; 1 μg/μl) or N-methyl-d-aspartic acid (NMDA; 2 μg/μl) enhanced basal NAc dopamine efflux. This iGluR-mediated potentiation of basal dopamine efflux was paralleled by an attenuation of LDT-evoked transient NAc dopamine efflux, suggesting that excitation of basal activity effectively inhibited the capacity of hindbrain afferents to elicit transient dopamine efflux. In line with this, post-NMDA infusion of the dopamine D2 autoreceptor (D2R) agonist quinpirole (1 μg/μl; intra-VTA) partially recovered NMDA-mediated attenuation of LDT-evoked NAc dopamine, while concurrently attenuating NMDA-mediated potentiation of basal dopamine efflux. Post-NMDA infusion of quinpirole (1 μg/μl) alone attenuated basal and LDT-evoked dopamine efflux. Taken together, these data reveal that hyperstimulation of basal dopamine transmission can stunt hindbrain burst-like stimulation-evoked dopamine efflux. Inhibitory autoreceptor mechanisms within the VTA help to partially recover the magnitude of phasic dopamine efflux, highlighting the importance of both iGluRs and D2 autoreceptors in maintaining the functional balance of tonic and phasic dopamine neurotransmission. Dysregulation of this balance may have important

  12. Research review: dopamine transfer deficit: a neurobiological theory of altered reinforcement mechanisms in ADHD.

    PubMed

    Tripp, Gail; Wickens, Jeff R

    2008-07-01

    This review considers the hypothesis that changes in dopamine signalling might account for altered sensitivity to positive reinforcement in children with ADHD. The existing evidence regarding dopamine cell activity in relation to positive reinforcement is reviewed. We focus on the anticipatory firing of dopamine cells brought about by a transfer of dopamine cell responses to cues that precede reinforcers. It is proposed that in children with ADHD there is diminished anticipatory dopamine cell firing, which we call the dopamine transfer deficit (DTD). The DTD theory leads to specific and testable predictions for human and animal research. The extent to which DTD explains symptoms of ADHD and effects of pharmacological interventions is discussed. We conclude by considering the neural changes underlying the etiology of DTD.

  13. The impact of a parkinsonian lesion on dynamic striatal dopamine transmission depends on nicotinic receptor activation

    PubMed Central

    Jennings, Katie A.; Platt, Nicola J.; Cragg, Stephanie J.

    2015-01-01

    Dopamine function is disturbed in Parkinson's disease (PD), but whether and how release of dopamine from surviving neurons is altered has long been debated. Nicotinic acetylcholine receptors (nAChRs) on dopamine axons powerfully govern dopamine release and could be critical contributing factors. We revisited whether fundamental properties of dopamine transmission are changed in a parkinsonian brain and tested the potentially profound masking effects of nAChRs. Using real-time detection of dopamine in mouse striatum after a partial 6-hydroxydopamine lesion and under nAChR inhibition, we reveal that dopamine signals show diminished sensitivity to presynaptic activity. This effect manifested as diminished contrast between DA release evoked by the lowest versus highest frequencies. This reduced activity-dependence was underpinned by loss of short-term facilitation of dopamine release, consistent with an increase in release probability (Pr). With nAChRs active, the reduced activity-dependence of dopamine release after a parkinsonian lesion was masked. Consequently, moment-by-moment variation in activity of nAChRs may lead to dynamic co-variation in dopamine signal impairments in PD. PMID:26117304

  14. A transient dopamine signal encodes subjective value and causally influences demand in an economic context

    PubMed Central

    Schelp, Scott A.; Pultorak, Katherine J.; Rakowski, Dylan R.; Gomez, Devan M.; Krzystyniak, Gregory; Das, Raibatak; Oleson, Erik B.

    2017-01-01

    The mesolimbic dopamine system is strongly implicated in motivational processes. Currently accepted theories suggest that transient mesolimbic dopamine release events energize reward seeking and encode reward value. During the pursuit of reward, critical associations are formed between the reward and cues that predict its availability. Conditioned by these experiences, dopamine neurons begin to fire upon the earliest presentation of a cue, and again at the receipt of reward. The resulting dopamine concentration scales proportionally to the value of the reward. In this study, we used a behavioral economics approach to quantify how transient dopamine release events scale with price and causally alter price sensitivity. We presented sucrose to rats across a range of prices and modeled the resulting demand curves to estimate price sensitivity. Using fast-scan cyclic voltammetry, we determined that the concentration of accumbal dopamine time-locked to cue presentation decreased with price. These data confirm and extend the notion that dopamine release events originating in the ventral tegmental area encode subjective value. Using optogenetics to augment dopamine concentration, we found that enhancing dopamine release at cue made demand more sensitive to price and decreased dopamine concentration at reward delivery. From these observations, we infer that value is decreased because of a negative reward prediction error (i.e., the animal receives less than expected). Conversely, enhancing dopamine at reward made demand less sensitive to price. We attribute this finding to a positive reward prediction error, whereby the animal perceives they received a better value than anticipated. PMID:29109253

  15. Control of extracellular dopamine at dendrite and axon terminals

    PubMed Central

    Ford, Christopher P.; Gantz, Stephanie C.; Phillips, Paul E. M.; Williams, John T.

    2010-01-01

    Midbrain dopamine neurons release dopamine from both axons and dendrites. The mechanism underlying release at these different sites has been proposed to differ. This study used electrochemical and electrophysiological methods to compare the time course and calcium-dependence of somatodendritc dopamine release in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) to that of axonal dopamine release in the dorsal striatum. The amount of dopamine released in the striatum was ~20 fold greater than in cell body regions of the VTA or SNc. However the calcium dependence and time to peak of the dopamine transients were similar. These results illustrate an unexpected overall similarity in the mechanisms of dopamine release in the striatum and cell body regions. To examine how diffusion regulates the time course of dopamine following release, dextran was added to the extracellular solution to slow diffusion. In the VTA, dextran slowed the rate of rise and fall of the extracellular dopamine transient as measured by fast-scan cyclic voltammetry (FSCV) yet did not alter the kinetics of the dopamine dependent inhibitory post-synaptic current (IPSC). Dextran failed to significantly alter the time course of the rise and fall of the dopamine transient in the striatum suggesting a more influential role for reuptake in the striatum. The conclusion is that the time course of dopamine within the extracellular space of the VTA is dependent on both diffusion and reuptake, whereas the activation of D2-receptors on dopamine neurons is primarily limited by reuptake. PMID:20484639

  16. Evaluation of the synuclein-y (SNCG) gene as a PPARy target in murine adipocytes, dorsal root ganglia somatosensory neurons, and human adipose tissue

    USDA-ARS?s Scientific Manuscript database

    Synuclein-gamma is highly expressed in both adipocytes and peripheral nervous system (PNS) somatosensory neurons. Its mRNA is induced during adipogenesis, increased in obese human white adipose tissue (WAT), may be coordinately regulated with leptin, and is decreased following treatment of murine 3T...

  17. Spatial Frequency Selectivity Is Impaired in Dopamine D2 Receptor Knockout Mice

    PubMed Central

    Souza, Bruno Oliveira Ferreira; Abou Rjeili, Mira; Quintana, Clémentine; Beaulieu, Jean M.; Casanova, Christian

    2018-01-01

    Dopamine is a neurotransmitter implicated in several brain functions, including vision. In the present study, we investigated the impacts of the lack of D2 dopamine receptors on the structure and function of the primary visual cortex (V1) of D2-KO mice using optical imaging of intrinsic signals. Retinotopic maps were generated in order to measure anatomo-functional parameters such as V1 shape, cortical magnification factor, scatter, and ocular dominance. Contrast sensitivity and spatial frequency selectivity (SF) functions were computed from responses to drifting gratings. When compared to control mice, none of the parameters of the retinotopic maps were affected by D2 receptor loss of function. While the contrast sensitivity function of D2-KO mice did not differ from their wild-type counterparts, SF selectivity function was significantly affected as the optimal SF and the high cut-off frequency (p < 0.01) were higher in D2-KO than in WT mice. These findings show that the lack of function of D2 dopamine receptors had no influence on cortical structure whereas it had a significant impact on the spatial frequency selectivity and high cut-off. Taken together, our results suggest that D2 receptors play a specific role on the processing of spatial features in early visual cortex while they do not seem to participate in its development. PMID:29379422

  18. The novel compound PBT434 prevents iron mediated neurodegeneration and alpha-synuclein toxicity in multiple models of Parkinson's disease.

    PubMed

    Finkelstein, David I; Billings, Jessica L; Adlard, Paul A; Ayton, Scott; Sedjahtera, Amelia; Masters, Colin L; Wilkins, Simon; Shackleford, David M; Charman, Susan A; Bal, Wojciech; Zawisza, Izabela A; Kurowska, Ewa; Gundlach, Andrew L; Ma, Sheri; Bush, Ashley I; Hare, Dominic J; Doble, Philip A; Crawford, Simon; Gautier, Elisabeth Cl; Parsons, Jack; Huggins, Penny; Barnham, Kevin J; Cherny, Robert A

    2017-06-28

    Elevated iron in the SNpc may play a key role in Parkinson's disease (PD) neurodegeneration since drug candidates with high iron affinity rescue PD animal models, and one candidate, deferirpone, has shown efficacy recently in a phase two clinical trial. However, strong iron chelators may perturb essential iron metabolism, and it is not yet known whether the damage associated with iron is mediated by a tightly bound (eg ferritin) or lower-affinity, labile, iron pool. Here we report the preclinical characterization of PBT434, a novel quinazolinone compound bearing a moderate affinity metal-binding motif, which is in development for Parkinsonian conditions. In vitro, PBT434 was far less potent than deferiprone or deferoxamine at lowering cellular iron levels, yet was found to inhibit iron-mediated redox activity and iron-mediated aggregation of α-synuclein, a protein that aggregates in the neuropathology. In vivo, PBT434 did not deplete tissue iron stores in normal rodents, yet prevented loss of substantia nigra pars compacta neurons (SNpc), lowered nigral α-synuclein accumulation, and rescued motor performance in mice exposed to the Parkinsonian toxins 6-OHDA and MPTP, and in a transgenic animal model (hA53T α-synuclein) of PD. These improvements were associated with reduced markers of oxidative damage, and increased levels of ferroportin (an iron exporter) and DJ-1. We conclude that compounds designed to target a pool of pathological iron that is not held in high-affinity complexes in the tissue can maintain the survival of SNpc neurons and could be disease-modifying in PD.

  19. A genetic determinant of the striatal dopamine response to alcohol in men

    PubMed Central

    Ramchandani, Vijay A.; Umhau, John; Pavon, Francisco J.; Ruiz-Velasco, Victor; Margas, Wojciech; Sun, Hui; Damadzic, Ruslan; Eskay, Robert; Schoor, Michael; Thorsell, Annika; Schwandt, Melanie L.; Sommer, Wolfgang H.; George, David T.; Parsons, Loren H.; Herscovitch, Peter; Hommer, Daniel; Heilig, Markus

    2010-01-01

    Excessive alcohol use, a major cause of morbidity and mortality, is less well understood than other addictive disorders. Dopamine release in ventral striatum is a common element of drug reward, but alcohol has an unusually complex pharmacology, and humans vary greatly in their alcohol responses. This variation is related to genetic susceptibility for alcoholism, which contributes more than half of alcoholism risk. Here, we report that a functional OPRM1 A118G polymorphism is a major determinant of striatal dopamine responses to alcohol. Social drinkers recruited based on OPRM1 genotype were challenged in separate sessions with alcohol and placebo under pharmacokinetically controlled conditions, and examined for striatal dopamine release using positron emission tomography and [11C]-raclopride displacement. A striatal dopamine response to alcohol was restricted to carriers of the minor 118G allele. To directly establish the causal role of OPRM1 A118G variation, we generated two humanized mouse lines, carrying the respective human sequence variant. Brain microdialysis showed a four-fold greater peak dopamine response to an alcohol challenge in h/mOPRM1-118GG than in h/mOPRM1-118AA mice. OPRM1 A118G variation is a genetic determinant of dopamine responses to alcohol, a mechanism by which it likely modulates alcohol reward. PMID:20479755

  20. A neuroprotective role for angiogenin in models of Parkinson’s Disease

    PubMed Central

    Steidinger, Trent U.; Standaert, David G.; Yacoubian, Talene A.

    2010-01-01

    We previously observed marked downregulation of the mRNA for angiogenin, a potent inducer of neovascularization, in a mouse model of Parkinson’s disease (PD) based on overexpression of alpha-synuclein. Angiogenin has also been recently implicated in the pathogenesis of amyotrophic lateral sclerosis. In this study, we confirmed that mouse angiogenin-1 protein is dramatically reduced in this transgenic alpha-synuclein mouse model of PD, and examined the effect of angiogenin in cellular models of PD. We found that endogenous angiogenin is present in two dopamine-producing neuroblastoma cell lines, SH-SY5Y and M17, and that exogenous angiogenin is taken up by these cells and leads to phosphorylation of Akt. Applied angiogenin protects against the cell death induced by the neurotoxins MPP+ and rotenone and reduces the activation of caspase-3. Together our data supports the importance of angiogenin in protecting against dopaminergic neuronal cell death and suggests its potential as a therapy for PD. PMID:21091473