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Sample records for mimetics activate trkb

  1. Biochemical and biophysical investigation of the brain-derived neurotrophic factor mimetic 7,8-dihydroxyflavone in the binding and activation of the TrkB receptor.

    PubMed

    Liu, Xia; Obianyo, Obiamaka; Chan, Chi Bun; Huang, Junjian; Xue, Shenghui; Yang, Jenny J; Zeng, Fanxing; Goodman, Mark; Ye, Keqiang

    2014-10-03

    7,8-dihydroxyflavone (7,8-DHF), a newly identified small molecular TrkB receptor agonist, rapidly activates TrkB in both primary neurons and the rodent brain and mimics the physiological functions of the cognate ligand BDNF. Accumulating evidence supports that 7,8-DHF exerts neurotrophic effects in a TrkB-dependent manner. Nonetheless, the differences between 7,8-DHF and BDNF in activating TrkB remain incompletely understood. Here we show that 7,8-DHF and BDNF exhibit different TrkB activation kinetics in which TrkB maturation may be implicated. Employing two independent biophysical approaches, we confirm that 7,8-DHF interacts robustly with the TrkB extracellular domain, with a Kd of ∼10 nm. Although BDNF transiently activates TrkB, leading to receptor internalization and ubiquitination/degradation, in contrast, 7,8-DHF-triggered TrkB phosphorylation lasts for hours, and the internalized receptors are not degraded. Notably, primary neuronal maturation may be required for 7,8-DHF but not for BDNF to elicit the full spectrum of TrkB signaling cascades. Hence, 7,8-DHF interacts robustly with the TrkB receptor, and its agonistic effect may be mediated by neuronal development and maturation.

  2. Biochemical and Biophysical Investigation of the Brain-derived Neurotrophic Factor Mimetic 7,8-Dihydroxyflavone in the Binding and Activation of the TrkB Receptor*

    PubMed Central

    Liu, Xia; Obianyo, Obiamaka; Chan, Chi Bun; Huang, Junjian; Xue, Shenghui; Yang, Jenny J.; Zeng, Fanxing; Goodman, Mark; Ye, Keqiang

    2014-01-01

    7,8-dihydroxyflavone (7,8-DHF), a newly identified small molecular TrkB receptor agonist, rapidly activates TrkB in both primary neurons and the rodent brain and mimics the physiological functions of the cognate ligand BDNF. Accumulating evidence supports that 7,8-DHF exerts neurotrophic effects in a TrkB-dependent manner. Nonetheless, the differences between 7,8-DHF and BDNF in activating TrkB remain incompletely understood. Here we show that 7,8-DHF and BDNF exhibit different TrkB activation kinetics in which TrkB maturation may be implicated. Employing two independent biophysical approaches, we confirm that 7,8-DHF interacts robustly with the TrkB extracellular domain, with a Kd of ∼10 nm. Although BDNF transiently activates TrkB, leading to receptor internalization and ubiquitination/degradation, in contrast, 7,8-DHF-triggered TrkB phosphorylation lasts for hours, and the internalized receptors are not degraded. Notably, primary neuronal maturation may be required for 7,8-DHF but not for BDNF to elicit the full spectrum of TrkB signaling cascades. Hence, 7,8-DHF interacts robustly with the TrkB receptor, and its agonistic effect may be mediated by neuronal development and maturation. PMID:25143381

  3. TDP6, a brain-derived neurotrophic factor-based trkB peptide mimetic, promotes oligodendrocyte myelination.

    PubMed

    Wong, Agnes W; Giuffrida, Lauren; Wood, Rhiannon; Peckham, Haley; Gonsalvez, David; Murray, Simon S; Hughes, Richard A; Xiao, Junhua

    2014-11-01

    Brain-derived neurotrophic factor (BDNF) plays critical roles in the development and maintenance of the central (CNS) and peripheral nervous systems (PNS). BDNF exerts its biological effects via tropomyosin-related kinase B (TrkB) and the p75 neurotrophin receptor (p75NTR). We have recently identified that BDNF promotes CNS myelination via oligodendroglial TrkB receptors. In order to selectively target TrkB to promote CNS myelination, we have used a putative TrkB agonist, a small multicyclic peptide (tricyclic dimeric peptide 6, TDP6) previously described by us that structurally mimics a region of BDNF that binds TrkB. We confirmed that TDP6 acts as a TrkB agonist as it provoked autophosphorylation of TrkB and its downstream signalling effector extracellular related-kinase 1 and 2 (Erk1/2) in primary oligodendrocytes. Using an in vitro myelination assay, we show that TDP6 significantly promotes myelination by oligodendrocytes in vitro, as evidenced by enhanced myelin protein expression and an increased number of myelinated axonal segments. In contrast, a second, structurally distinct BDNF mimetic (cyclo-dPAKKR) that targets p75NTR had no effect upon oligodendrocyte myelination in vitro, despite the fact that cyclo-dPAKKR is a very effective promoter of peripheral (Schwann cell) myelination. The selectivity of TDP6 was further verified by using TrkB-deficient oligodendrocytes, in which TDP6 failed to promote myelination, indicating that the pro-myelinating effect of TDP6 is oligodendroglial TrkB-dependent. Together, our results demonstrate that TDP6 is a novel BDNF mimetic that promotes oligodendrocyte myelination in vitro via targeting TrkB.

  4. Small molecules activating TrkB receptor for treating a variety of CNS disorders.

    PubMed

    Zeng, Yan; Wang, Xiaonan; Wang, Qiang; Liu, Shumin; Hu, Xiamin; McClintock, Shawn M

    2013-11-01

    The brain-derived neurotrophic factor (BDNF) and its high affinity receptor tropomyosin-receptor-kinase B (TrkB) play a critical role in neuronal differentiation and survival, synapse plasticity, and memory. Indeed, both have been implicated in the pathophysiology of numerous diseases. Although the remarkable therapeutic potential of BDNF has generated much research over the past decade, the poor pharmacokinetics and adverse side effect profile have limited its clinical usefulness of BDNF. Small compounds that mimic BDNF's neurotrophic signaling and overcome the pharmacokinetic and side effect barriers may have greater therapeutic potential. The purpose of this review is to provide a survey of the various strategies taken towards the development of small molecule mimetics for BDNF and the selective TrkB agonist. A particular focus was placed on TrkB agonist 7, 8-dihydroxyflavone, which modulates multiple functions and has demonstrated remarkable therapeutic efficacy in a variety of central nervous system disease models. Two other small molecules included in this review are adenosine A2A receptor agonists that indirectly activate TrkB, and TrkB binding domains of BDNF, loop II-LM22A compounds that directly activate TrkB. These alternative molecules have shown promise in preclinical studies and may be included in prospective clinical investigations.

  5. Activation of muscular TrkB by its small molecular agonist 7,8-dihydroxyflavone sex-dependently regulates energy metabolism in diet-induced obese mice.

    PubMed

    Chan, Chi Bun; Tse, Margaret Chui Ling; Liu, Xia; Zhang, Shuai; Schmidt, Robin; Otten, Reed; Liu, Liegang; Ye, Keqiang

    2015-03-19

    Chronic activation of brain-derived neurotrophic factor (BDNF) receptor TrkB is a potential method to prevent development of obesity, but the short half-life and nonbioavailable nature of BDNF hampers validation of the hypothesis. We report here that activation of muscular TrkB by the BDNF mimetic, 7,8-dihydroxyflavone (7,8-DHF), is sufficient to protect the development of diet-induced obesity in female mice. Using in vitro and in vivo models, we found that 7,8-DHF treatment enhanced the expression of uncoupling protein 1 (UCP1) and AMP-activated protein kinase (AMPK) activity in skeletal muscle, which resulted in increased systemic energy expenditure, reduced adiposity, and improved insulin sensitivity in female mice fed a high-fat diet. This antiobesity activity of 7,8-DHF is muscular TrkB-dependent as 7,8-DHF cannot mitigate diet-induced obesity in female muscle-specific TrkB knockout mice. Hence, our data reveal that chronic activation of muscular TrkB is useful in alleviating obesity and its complications.

  6. A selective TrkB agonist with potent neurotrophic activities by 7,8-dihydroxyflavone

    PubMed Central

    Jang, Sung-Wuk; Liu, Xia; Yepes, Manuel; Shepherd, Kennie R.; Miller, Gary W.; Liu, Yang; Wilson, W. David; Xiao, Ge; Blanchi, Bruno; Sun, Yi E.; Ye, Keqiang

    2010-01-01

    Brain-derived neurotrophic factor (BDNF), a cognate ligand for the tyrosine kinase receptor B (TrkB) receptor, mediates neuronal survival, differentiation, synaptic plasticity, and neurogenesis. However, BDNF has a poor pharmacokinetic profile that limits its therapeutic potential. Here we report the identification of 7,8-dihydroxyflavone as a bioactive high-affinity TrkB agonist that provokes receptor dimerization and autophosphorylation and activation of downstream signaling. 7,8-Dihydroxyflavone protected wild-type, but not TrkB-deficient, neurons from apoptosis. Administration of 7,8-dihydroxyflavone to mice activated TrkB in the brain, inhibited kainic acid-induced toxicity, decreased infarct volumes in stroke in a TrkB-dependent manner, and was neuroprotective in an animal model of Parkinson disease. Thus, 7,8-dihydroxyflavone imitates BDNF and acts as a robust TrkB agonist, providing a powerful therapeutic tool for the treatment of various neurological diseases. PMID:20133810

  7. Fisetin provides antidepressant effects by activating the TrkB signal pathway in mice.

    PubMed

    Wang, Yamin; Wang, Bin; Lu, Jiaqi; Shi, Haixia; Gong, Siyi; Wang, Yufan; Hamdy, Ronald C; Chua, Balvin H L; Yang, Lingli; Xu, Xingshun

    2017-09-25

    Depression has been associated with a low-grade chronic inflammatory state, suggesting a potential therapeutic role for anti-inflammatory agents. Fisetin is a naturally occurring flavonoid in strawberries that has anti-inflammatory activities, but whether fisetin has antidepressant effects is unknown. In this study, we exposed mice to spatial restraint for 2 weeks with or without treatment with fisetin. Immobility time in the forced swimming and tail suspension test after this restraint increased in the untreated group, but this increase did not occur in the fisetin group. We administered fisetin to Abelson helper integration site-1 (Ahi1) knockout mice, which have depressive phenotypes. We found that fisetin attenuated the depressive phenotype of these Ahi1 knockout mice. We further investigated the potential mechanism of fisetin's antidepressant effects. Because TrkB is a critical signaling pathway in the mechanisms of depression, we examined whether phosphorylated TrkB was involved in the antidepressant effects of fisetin. We found that fisetin increased phosphorylated TrkB level without altering total TrkB; this increase was attenuated by K252a, a specific TrkB inhibitor. Taken together, our results demonstrated that fisetin may have therapeutic potential for treating depression and that this antidepressant effect may be mediated by the activation of the TrkB signaling pathway. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  8. Shp-2 regulates the TrkB receptor activity in the retinal ganglion cells under glaucomatous stress.

    PubMed

    Gupta, Vivek K; You, Yuyi; Klistorner, Alexander; Graham, Stuart L

    2012-11-01

    Tropomyosin-receptor-kinase B (TrkB receptor) activation plays an important role in the survival of retinal ganglion cells (RGCs). This study reports a novel finding that, SH2 domain-containing phosphatase-2 (Shp-2) binds to the TrkB receptor in RGCs and negatively regulates its activity under glaucomatous stress. This enhanced binding of TrkB and Shp2 is mediated through caveolin. Caveolin 1 and 3 undergo hyper-phosphorylation in RGCs under stress and bind to the Shp2 phosphatase. Shp2 undergoes activation under glaucomatous stress conditions in RGCs in vivo with a concurrent loss of TrkB activity. Inhibiting the Shp2 phosphatase restored TrkB activity in cells exposed to excitotoxic and oxidative stress. Collectively, these findings implicate a molecular basis of Shp2 mediated TrkB deactivation leading to RGC degeneration observed in glaucoma. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. 5-HT7 receptor activation promotes an increase in TrkB receptor expression and phosphorylation

    PubMed Central

    Samarajeewa, Anshula; Goldemann, Lolita; Vasefi, Maryam S.; Ahmed, Nawaz; Gondora, Nyasha; Khanderia, Chandni; Mielke, John G.; Beazely, Michael A.

    2014-01-01

    The serotonin (5-HT) type 7 receptor is expressed throughout the CNS including the cortex and hippocampus. We have previously demonstrated that the application of 5-HT7 receptor agonists to primary hippocampal neurons and SH-SY5Y cells increases platelet-derived growth factor (PDGF) receptor expression and promotes neuroprotection against N-methyl-D-aspartate-(NMDA)-induced toxicity. The tropomyosin-related kinase B (TrkB) receptor is one of the receptors for brain-derived neurotrophic factor (BDNF) and is associated with neurodevelopmental and neuroprotective effects. Application of LP 12 to primary cerebral cortical cultures, SH-SY5Y cells, as well as the retinal ganglion cell line, RGC-5, increased both the expression of full length TrkB as well as its basal phosphorylation state at tyrosine 816. The increase in TrkB expression and phosphorylation was observed as early as 30 min after 5-HT7 receptor activation. In addition to full-length TrkB, kinase domain-deficient forms may be expressed and act as dominant-negative proteins toward the full length receptor. We have identified distinct patterns of TrkB isoform expression across our cell lines and cortical cultures. Although TrkB receptor expression is regulated by cyclic AMP and Gαs-coupled GPCRs in several systems, we demonstrate that, depending on the model system, pathways downstream of both Gαs and Gα12 are involved in the regulation of TrkB expression by 5-HT7 receptors. Given the number of psychiatric and degenerative diseases associated with TrkB/BDNF deficiency and the current interest in developing 5-HT7 receptor ligands as pharmaceuticals, identifying signaling relationships between these two receptors will aid in our understanding of the potential therapeutic effects of 5-HT7 receptor ligands. PMID:25426041

  10. 5-HT7 receptor activation promotes an increase in TrkB receptor expression and phosphorylation.

    PubMed

    Samarajeewa, Anshula; Goldemann, Lolita; Vasefi, Maryam S; Ahmed, Nawaz; Gondora, Nyasha; Khanderia, Chandni; Mielke, John G; Beazely, Michael A

    2014-01-01

    The serotonin (5-HT) type 7 receptor is expressed throughout the CNS including the cortex and hippocampus. We have previously demonstrated that the application of 5-HT7 receptor agonists to primary hippocampal neurons and SH-SY5Y cells increases platelet-derived growth factor (PDGF) receptor expression and promotes neuroprotection against N-methyl-D-aspartate-(NMDA)-induced toxicity. The tropomyosin-related kinase B (TrkB) receptor is one of the receptors for brain-derived neurotrophic factor (BDNF) and is associated with neurodevelopmental and neuroprotective effects. Application of LP 12 to primary cerebral cortical cultures, SH-SY5Y cells, as well as the retinal ganglion cell line, RGC-5, increased both the expression of full length TrkB as well as its basal phosphorylation state at tyrosine 816. The increase in TrkB expression and phosphorylation was observed as early as 30 min after 5-HT7 receptor activation. In addition to full-length TrkB, kinase domain-deficient forms may be expressed and act as dominant-negative proteins toward the full length receptor. We have identified distinct patterns of TrkB isoform expression across our cell lines and cortical cultures. Although TrkB receptor expression is regulated by cyclic AMP and Gαs-coupled GPCRs in several systems, we demonstrate that, depending on the model system, pathways downstream of both Gαs and Gα12 are involved in the regulation of TrkB expression by 5-HT7 receptors. Given the number of psychiatric and degenerative diseases associated with TrkB/BDNF deficiency and the current interest in developing 5-HT7 receptor ligands as pharmaceuticals, identifying signaling relationships between these two receptors will aid in our understanding of the potential therapeutic effects of 5-HT7 receptor ligands.

  11. BDNF heightens the sensitivity of motor neurons to excitotoxic insults through activation of TrkB

    NASA Technical Reports Server (NTRS)

    Hu, Peter; Kalb, Robert G.; Walton, K. D. (Principal Investigator)

    2003-01-01

    The survival promoting and neuroprotective actions of brain-derived neurotrophic factor (BDNF) are well known but under certain circumstances this growth factor can also exacerbate excitotoxic insults to neurons. Prior exploration of the receptor through which BDNF exerts this action on motor neurons deflects attention away from p75. Here we investigated the possibility that BDNF acts through the receptor tyrosine kinase, TrkB, to confer on motor neurons sensitivity to excitotoxic challenge. We blocked BDNF activation of TrkB using a dominant negative TrkB mutant or a TrkB function blocking antibody, and found that this protected motor neurons against excitotoxic insult in cultures of mixed spinal cord neurons. Addition of a function blocking antibody to BDNF to mixed spinal cord neuron cultures is also neuroprotective indicating that endogenously produced BDNF participates in vulnerability to excitotoxicity. We next examined the intracellular signaling cascades that are engaged upon TrkB activation. Previously we found that inhibition of the phosphatidylinositide-3'-kinase (PI3'K) pathway blocks BDNF-induced excitotoxic sensitivity. Here we show that expression of a constitutively active catalytic subunit of PI3'K, p110, confers excitotoxic sensitivity (ES) upon motor neurons not incubated with BDNF. Parallel studies with purified motor neurons confirm that these events are likely to be occuring specifically within motor neurons. The abrogation of BDNF's capacity to accentuate excitotoxic insults may make it a more attractive neuroprotective agent.

  12. BDNF heightens the sensitivity of motor neurons to excitotoxic insults through activation of TrkB

    NASA Technical Reports Server (NTRS)

    Hu, Peter; Kalb, Robert G.; Walton, K. D. (Principal Investigator)

    2003-01-01

    The survival promoting and neuroprotective actions of brain-derived neurotrophic factor (BDNF) are well known but under certain circumstances this growth factor can also exacerbate excitotoxic insults to neurons. Prior exploration of the receptor through which BDNF exerts this action on motor neurons deflects attention away from p75. Here we investigated the possibility that BDNF acts through the receptor tyrosine kinase, TrkB, to confer on motor neurons sensitivity to excitotoxic challenge. We blocked BDNF activation of TrkB using a dominant negative TrkB mutant or a TrkB function blocking antibody, and found that this protected motor neurons against excitotoxic insult in cultures of mixed spinal cord neurons. Addition of a function blocking antibody to BDNF to mixed spinal cord neuron cultures is also neuroprotective indicating that endogenously produced BDNF participates in vulnerability to excitotoxicity. We next examined the intracellular signaling cascades that are engaged upon TrkB activation. Previously we found that inhibition of the phosphatidylinositide-3'-kinase (PI3'K) pathway blocks BDNF-induced excitotoxic sensitivity. Here we show that expression of a constitutively active catalytic subunit of PI3'K, p110, confers excitotoxic sensitivity (ES) upon motor neurons not incubated with BDNF. Parallel studies with purified motor neurons confirm that these events are likely to be occuring specifically within motor neurons. The abrogation of BDNF's capacity to accentuate excitotoxic insults may make it a more attractive neuroprotective agent.

  13. Flavonoid derivative 7,8-DHF attenuates TBI pathology via TrkB activation.

    PubMed

    Agrawal, Rahul; Noble, Emily; Tyagi, Ethika; Zhuang, Yumei; Ying, Zhe; Gomez-Pinilla, Fernando

    2015-05-01

    Traumatic brain injury (TBI) is followed by a state of metabolic dysfunction, affecting the ability of neurons to use energy and support brain plasticity; there is no effective therapy to counteract the TBI pathology. Brain-derived neurotrophic factor (BDNF) has an exceptional capacity to support metabolism and plasticity, which highly contrasts with its poor pharmacological profile. We evaluated the action of a flavonoid derivative 7,8-dihydroxyflavone (7,8-DHF), a BDNF receptor (TrkB) agonist with the pharmacological profile congruent for potential human therapies. Treatment with 7,8-DHF (5mg/kg, ip, daily for 7 days) was effective to ameliorate the effects of TBI on plasticity markers (CREB phosphorylation, GAP-43 and syntaxin-3 levels) and memory function in Barnes maze test. Treatment with 7,8-DHF restored the decrease in protein and phenotypic expression of TrkB phosphorylation after TBI. In turn, intrahippocampal injections of K252a, a TrkB antagonist, counteracted the 7,8-DHF induced TrkB signaling activation and memory improvement in TBI, suggesting the pivotal role of TrkB signaling in cognitive performance after brain injury. A potential action of 7,8-DHF on cell energy homeostasis was corroborated by the normalization in levels of PGC-1α, TFAM, COII, AMPK and SIRT1 in animals subjected to TBI. Results suggest a potential mechanism by which 7,8-DHF counteracts TBI pathology via activation of the TrkB receptor and engaging the interplay between cell energy management and synaptic plasticity. Since metabolic dysfunction is an important risk factor for the development of neurological and psychiatric disorders, these results set a precedent for the therapeutic use of 7,8-DHF in a larger context.

  14. Flavonoid derivative 7,8-DHF attenuates TBI pathology via TrkB activation

    PubMed Central

    Agrawal, Rahul; Noble, Emily; Tyagi, Ethika; Zhuang, Yumei; Ying, Zhe; Gomez-Pinilla, Fernando

    2015-01-01

    Traumatic brain injury (TBI) is followed by a state of metabolic dysfunction, affecting the ability of neurons to use energy and support brain plasticity; there is no effective therapy to counteract the TBI pathology. Brain-derived neurotrophic factor (BDNF) has an exceptional capacity to support metabolism and plasticity, which highly contrasts with its poor pharmacological profile. We evaluated the action of a flavonoid derivative 7,8-dihydroxyflavone (7,8-DHF), a BDNF receptor (TrkB) agonist with the pharmacological profile congruent for potential human therapies. Treatment with 7,8-DHF (5 mg/kg, ip, daily for 7 days) was effective to ameliorate the effects of TBI on plasticity markers (CREB phosphorylation, GAP-43 and syntaxin-3 levels) and memory function in Barnes maze test. Treatment with 7,8-DHF restored the decrease in protein and phenotypic expression of TrkB phosphorylation after TBI. In turn, intrahippocampal injections of K252a, a TrkB antagonist, counteracted the 7,8-DHF induced TrkB signaling activation and memory improvement in TBI, suggesting the pivotal role of TrkB signaling in cognitive performance after brain injury. A potential action of 7,8-DHF on cell energy homeostasis was corroborated by the normalization in levels of PGC-1α, TFAM, COII, AMPK and SIRT1 in animals subjected to TBI. Results suggest a potential mechanism by which 7,8-DHF counteracts TBI pathology via activation of the TrkB receptor and engaging the interplay between cell energy management and synaptic plasticity. Since metabolic dysfunction is an important risk factor for the development of neurological and psychiatric disorders, these results set a precedent for the therapeutic use of 7,8-DHF in a larger context. PMID:25661191

  15. O-Methylated Metabolite of 7,8-Dihydroxyflavone Activates TrkB Receptor and Displays Antidepressant Activity

    PubMed Central

    Liu, Xia; Qi, Qi; Xiao, Ge; Li, Jingyu; Luo, Hongbo R.; Ye, Keqiang

    2016-01-01

    7,8-Dihydroxyflavone (7,8-DHF) acts as a TrkB receptor-specific agonist. It mimics the physiological actions of brain-derived neurotrophic factor (BDNF) and demonstrates remarkable therapeutic efficacy in animal models of various neurological diseases. Nonetheless, its in vivo pharmacokinetic profiles and metabolism remain unclear. Here we report that 7,8-DHF and its O-methylated metabolites distribute in mouse brain after oral administration. Both hydroxy groups can be mono-methylated, and the mono-methylated metabolites activate TrkB in vitro and in vivo. Blocking methylation, using COMT inhibitors, diminishes the agonistic effect of TrkB activation by 7,8-DHF or 4′-dimethylamino-7,8-DHF, supporting the contribution of the methylated metabolite to TrkB activation in mouse brain. Moreover, we have synthesized several methylated metabolite derivatives, and they also potently activate the TrkB receptor and reduce immobility in both forced swim test and tail suspension test, indicating that these methylated metabolites may possess antidepressant activity. Hence, our data demonstrate that 7,8-DHF is orally bioavailable and can penetrate the brain-blood barrier. The O-methylated metabolites are implicated in TrkB receptor activation in the brain. PMID:23445871

  16. Aspartate and glutamate mimetic structures in biologically active compounds.

    PubMed

    Stefanic, Peter; Dolenc, Marija Sollner

    2004-04-01

    Glutamate and aspartate are frequently recognized as key structural elements for the biological activity of natural peptides and synthetic compounds. The acidic side-chain functionality of both the amino acids provides the basis for the ionic interaction and subsequent molecular recognition by specific receptor sites that results in the regulation of physiological or pathophysiological processes in the organism. In the development of new biologically active compounds that possess the ability to modulate these processes, compounds offering the same type of interactions are being designed. Thus, using a peptidomimetic design approach, glutamate and aspartate mimetics are incorporated into the structure of final biologically active compounds. This review covers different bioisosteric replacements of carboxylic acid alone, as well as mimetics of the whole amino acid structure. Amino acid analogs presented include those with different distances between anionic moieties, and analogs with additional functional groups that result in conformational restriction or alternative interaction sites. The article also provides an overview of different cyclic structures, including various cycloalkane, bicyclic and heterocyclic analogs, that lead to conformational restriction. Higher di- and tripeptide mimetics in which carboxylic acid functionality is incorporated into larger molecules are also reviewed. In addition to the mimetic structures presented, emphasis in this article is placed on their steric and electronic properties. These mimetics constitute a useful pool of fragments in the design of new biologically active compounds, particularly in the field of RGD mimetics and excitatory amino acid agonists and antagonists.

  17. Brain-derived neurotrophic factor but not vesicular zinc promotes TrkB activation within mossy fibers of mouse hippocampus in vivo.

    PubMed

    Helgager, Jeffrey; Huang, Yang Zhong; Mcnamara, James O

    2014-12-01

    The neurotrophin receptor, TrkB receptor tyrosine kinase, is critical to central nervous system (CNS) function in health and disease. Elucidating the ligands mediating TrkB activation in vivo will provide insights into its diverse roles in the CNS. The canonical ligand for TrkB is brain-derived neurotrophic factor (BDNF). A diversity of stimuli also can activate TrkB in the absence of BDNF, a mechanism termed transactivation. Zinc, a divalent cation packaged in synaptic vesicles along with glutamate in axons of mammalian cortical neurons, can transactivate TrkB in neurons and heterologous cells in vitro. Yet the contributions of BDNF and zinc to TrkB activation in vivo are unknown. To address these questions, we conducted immunohistochemical (IHC) studies of the hippocampal mossy fiber axons and boutons using an antibody selective for pY816 of TrkB, a surrogate measure of TrkB activation. We found that conditional deletion of BDNF resulted in a reduction of pY816 in axons and synaptic boutons of hippocampal mossy fibers, thereby implicating BDNF in activation of TrkB in vivo. Unexpectedly, pY816 immunoreactivity was increased in axons but not synaptic boutons of mossy fibers in ZnT3 knockout mice that lack vesicular zinc. Marked increases of BDNF content were evident within the hippocampus of ZnT3 knockout mice and genetic elimination of BDNF reduced pY816 immunoreactivity in these mice, implicating BDNF in enhanced TrkB activation mediated by vesicular zinc depletion. These findings support the conclusion that BDNF but not vesicular zinc activates TrkB in hippocampal mossy fiber axons under physiological conditions.

  18. Vagal nerve stimulation rapidly activates brain-derived neurotrophic factor receptor TrkB in rat brain.

    PubMed

    Furmaga, Havan; Carreno, Flavia Regina; Frazer, Alan

    2012-01-01

    Vagal nerve stimulation (VNS) has been approved for treatment-resistant depression. Many antidepressants increase expression of brain-derived neurotrophic factor (BDNF) in brain or activate, via phosphorylation, its receptor, TrkB. There have been no studies yet of whether VNS would also cause phosphorylation of TrkB. Western blot analysis was used to evaluate the phosphorylation status of TrkB in the hippocampus of rats administered VNS either acutely or chronically. Acute effects of VNS were compared with those caused by fluoxetine or desipramine (DMI) whereas its chronic effects were compared with those of sertraline or DMI. All treatments, given either acutely or chronically, significantly elevated phosphorylation of tyrosines 705 and 816 on TrkB in the hippocampus. However, only VNS increased the phosphorylation of tyrosine 515, with both acute and chronic administration causing this effect. Pretreatment with K252a, a nonspecific tyrosine kinase inhibitor, blocked the phosphorylation caused by acute VNS at all three tyrosines. Downstream effectors of Y515, namely Akt and ERK, were also phosphorylated after acute treatment with VNS, whereas DMI did not cause this effect. VNS rapidly activates TrkB phosphorylation and this effect persists over time. VNS-induced phosphorylation of tyrosine 515 is distinct from the effect of standard antidepressant drugs.

  19. Increased Cortical Synaptic Activation of TrkB and Downstream Signaling Markers in a Mouse Model of Down Syndrome

    PubMed Central

    Nosheny, RL; Belichenko, PV; Busse, BL; Weissmiller, AM; Dang, V; Das, D; Fahimi, A; Salehi, A; Smith, SJ; Mobley, WC

    2015-01-01

    Down Syndrome (DS), trisomy 21, is characterized by synaptic abnormalities and cognitive deficits throughout the lifespan and with development of Alzheimer’s disease (AD) neuropathology and progressive cognitive decline in adults. Synaptic abnormalities are also present in the Ts65Dn mouse model of DS, but which synapses are affected and the mechanisms underlying synaptic dysfunction are unknown. Here we show marked increases in the levels and activation status of TrkB and associated signaling proteins in cortical synapses in Ts65Dn mice. Proteomic analysis at the single synapse level of resolution using array tomography (AT) uncovered increased colocalization of activated TrkB with signaling endosome related proteins, and demonstrated increased TrkB signaling. The extent of increases in TrkB signaling differed in each of the cortical layers examined and with respect to the type of synapse, with the most marked increases seen in inhibitory synapses. These findings are evidence of markedly abnormal TrkB-mediated signaling in synapses. They raise the possibility that dysregulated TrkB signaling contributes to synaptic dysfunction and cognitive deficits in DS. PMID:25753471

  20. BH3 mimetics activate multiple pro-autophagic pathways.

    PubMed

    Malik, S A; Orhon, I; Morselli, E; Criollo, A; Shen, S; Mariño, G; BenYounes, A; Bénit, P; Rustin, P; Maiuri, M C; Kroemer, G

    2011-09-15

    The BH3 mimetic ABT737 induces autophagy by competitively disrupting the inhibitory interaction between the BH3 domain of Beclin 1 and the anti-apoptotic proteins Bcl-2 and Bcl-X(L), thereby stimulating the Beclin 1-dependent allosteric activation of the pro-autophagic lipid kinase VPS34. Here, we examined whether ABT737 stimulates other pro-autophagic signal-transduction pathways. ABT737 caused the activating phosphorylation of AMP-dependent kinase (AMPK) and of the AMPK substrate acetyl CoA carboxylase, the activating phosphorylation of several subunits of the inhibitor of NF-κB (IκB) kinase (IKK) and the hyperphosphorylation of the IKK substrate IκB, inhibition of the activity of mammalian target of rapamycin (mTOR) and consequent dephosphorylation of the mTOR substrate S6 kinase. In addition, ABT737 treatment dephosphorylates (and hence likewise inhibits) p53, glycogen synthase kinase-3 and Akt. All these effects were shared by ABT737 and another structurally unrelated BH3 mimetic, HA14-1. Functional experiments revealed that pharmacological or genetic inhibition of IKK, Sirtuin and the p53-depleting ubiquitin ligase MDM2 prevented ABT737-induced autophagy. These results point to unexpected and pleiotropic pro-autophagic effects of BH3 mimetics involving the modulation of multiple signalling pathways.

  1. TrkB Activators for the Treatment of Traumatic Vision Loss

    DTIC Science & Technology

    2017-06-01

    correlations  of all three cytokines to Cd3 in our blast  database (Fig 4C).      Ocular blast injury leads to progressive vision  loss  associated with...Award Number: W81XWH-12-1-0436 TITLE: TrkB Activators for the Treatment of Traumatic Vision Loss PRINCIPAL INVESTIGATOR: Michael P. Luvone...Traumatic Vision Loss 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-12-1-0436 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Betty Diamond 5d. PROJECT

  2. Pharmacologically diverse antidepressants rapidly activate brain-derived neurotrophic factor receptor TrkB and induce phospholipase-Cgamma signaling pathways in mouse brain.

    PubMed

    Rantamäki, Tomi; Hendolin, Panu; Kankaanpää, Aino; Mijatovic, Jelena; Piepponen, Petteri; Domenici, Enrico; Chao, Moses V; Männistö, Pekka T; Castrén, Eero

    2007-10-01

    Previous studies suggest that brain-derived neurotrophic factor and its receptor TrkB are critically involved in the therapeutic actions of antidepressant drugs. We have previously shown that the antidepressants imipramine and fluoxetine produce a rapid autophosphorylation of TrkB in the rodent brain. In the present study, we have further examined the biochemical and functional characteristics of antidepressant-induced TrkB activation in vivo. We show that all the antidepressants examined, including inhibitors of monoamine transporters and metabolism, activate TrkB rapidly in the rodent anterior cingulate cortex and hippocampus. Furthermore, the results indicate that acute and long-term antidepressant treatments induce TrkB-mediated activation of phospholipase-Cgamma1 (PLCgamma1) and increase the phosphorylation of cAMP-related element binding protein, a major transcription factor mediating neuronal plasticity. In contrast, we have not observed any modulation of the phosphorylation of TrkB Shc binding site, phosphorylation of mitogen-activated protein kinase or AKT by antidepressants. We also show that in the forced swim test, the behavioral effects of specific serotonergic antidepressant citalopram, but not those of the specific noradrenergic antidepressant reboxetine, are crucially dependent on TrkB signaling. Finally, brain monoamines seem to be critical mediators of antidepressant-induced TrkB activation, as antidepressants reboxetine and citalopram do not produce TrkB activation in the brains of serotonin- or norepinephrine-depleted mice. In conclusion, our data suggest that rapid activation of the TrkB neurotrophin receptor and PLCgamma1 signaling is a common mechanism for all antidepressant drugs.

  3. Genetic dissection of TrkB activated signalling pathways required for specific aspects of the taste system

    PubMed Central

    2014-01-01

    Background Neurotrophin-4 (NT-4) and brain derived neurotrophic factor (BDNF) bind to the same receptor, Ntrk2/TrkB, but play distinct roles in the development of the rodent gustatory system. However, the mechanisms underlying these processes are lacking. Results Here, we demonstrate, in vivo, that single or combined point mutations in major adaptor protein docking sites on TrkB receptor affect specific aspects of the mouse gustatory development, known to be dependent on BDNF or NT-4. In particular, mice with a mutation in the TrkB-SHC docking site had reduced gustatory neuron survival at both early and later stages of development, when survival is dependent on NT-4 and BDNF, respectively. In addition, lingual innervation and taste bud morphology, both BDNF-dependent functions, were altered in these mutants. In contrast, mutation of the TrkB-PLCγ docking site alone did not affect gustatory neuron survival. Moreover, innervation to the tongue was delayed in these mutants and taste receptor expression was altered. Conclusions We have genetically dissected pathways activated downstream of the TrkB receptor that are required for specific aspects of the taste system controlled by the two neurotrophins NT-4 and BDNF. In addition, our results indicate that TrkB also regulate the expression of specific taste receptors by distinct signalling pathways. These results advance our knowledge of the biology of the taste system, one of the fundamental sensory systems crucial for an organism to relate to the environment. PMID:25256039

  4. Arginine mimetic structures in biologically active antagonists and inhibitors.

    PubMed

    Masic, Lucija Peterlin

    2006-01-01

    Peptidomimetics have found wide application as bioavailable, biostable, and potent mimetics of naturally occurring biologically active peptides. L-Arginine is a guanidino group-containing basic amino acid, which is positively charged at neutral pH and is involved in many important physiological and pathophysiological processes. Many enzymes display a preference for the arginine residue that is found in many natural substrates and in synthetic inhibitors of many trypsin-like serine proteases, e.g. thrombin, factor Xa, factor VIIa, trypsin, and in integrin receptor antagonists, used to treat many blood-coagulation disorders. Nitric oxide (NO), which is produced by oxidation of L-arginine in an NADPH- and O(2)-dependent process catalyzed by isoforms of nitric oxide synthase (NOS), exhibits diverse roles in both normal and pathological physiologies and has been postulated to be a contributor to the etiology of various diseases. Development of NOS inhibitors as well as analogs and mimetics of the natural substrate L-arginine, is desirable for potential therapeutic use and for a better understanding of their conformation when bound in the arginine binding site. The guanidino residue of arginine in many substrates, inhibitors, and antagonists forms strong ionic interactions with the carboxylate of an aspartic acid moiety, which provides specificity for the basic amino acid residue in the active side. However, a highly basic guanidino moiety incorporated in enzyme inhibitors or receptor antagonists is often associated with low selectivity and poor bioavailability after peroral application. Thus, significant effort is focused on the design and preparation of arginine mimetics that can confer selective inhibition for specific trypsin-like serine proteases and NOS inhibitors as well as integrin receptor antagonists and possess reduced basicity for enhanced oral bioavailability. This review will describe the survey of arginine mimetics designed to mimic the function of the

  5. Improved Oxidase Mimetic Activity by Praseodymium Incorporation into Ceria Nanocubes.

    PubMed

    Jiang, Lei; Fernandez-Garcia, Susana; Tinoco, Miguel; Yan, Zhaoxia; Xue, Qi; Blanco, Ginesa; Calvino, Jose J; Hungria, Ana B; Chen, Xiaowei

    2017-06-07

    Ceria nanocubes (NC) modified with increasing concentrations of praseodymium (5, 10, 15, and 20 mol %) have been successfully synthesized by a hydrothermal method. The as-synthesized Pr-modified ceria nanocubes exhibit an enhanced oxidase-like activity on the organic dye TMB within a wide range of concentrations and durations. The oxidase activity increases with increasing Pr amounts in Pr-modified ceria nanocubes within the investigated concentration range. Meanwhile, these Pr-modified ceria nanocubes also show higher reducibility than pure ceria nanocubes. The kinetics of their oxidase mimetic activity is fitted with the Michaelis-Menten equation. A mechanism has been proposed on how the Pr incorporation could affect the energy level of the bands in ceria and hence facilitate the TMB oxidation reaction. The presence of Pr(3+) species on the surface also contributes to the increasing activity of the Pr-modified ceria nanocubes present higher oxidase activity than pure ceria nanocubes.

  6. TrkB kinase activity is critical for recovery of respiratory function after cervical spinal cord hemisection.

    PubMed

    Mantilla, Carlos B; Greising, Sarah M; Stowe, Jessica M; Zhan, Wen-Zhi; Sieck, Gary C

    2014-11-01

    Neuroplasticity following spinal cord injury contributes to spontaneous recovery over time. Recent studies highlight the important role of brain-derived neurotrophic factor (BDNF) signaling via the high-affinity tropomyosin-related kinase (Trk) receptor subtype B (TrkB) in recovery of rhythmic diaphragm activity following unilateral spinal hemisection at C2 (C2SH). We hypothesized that TrkB kinase activity is necessary for spontaneous recovery of diaphragm activity post-C2SH. A chemical-genetic approach employing adult male TrkB(F616A) mice (n=49) was used to determine the impact of inhibiting TrkB kinase activity by the phosphoprotein phosphatase 1 inhibitor derivative 1NMPP1 on recovery of ipsilateral hemidiaphragm EMG activity. In mice, C2SH was localized primarily to white matter tracts comprising the lateral funiculus. The extent of damaged spinal cord (~27%) was similar regardless of the presence of functional recovery, consistent with spontaneous recovery reflecting neuroplasticity primarily of contralateral spared descending pathways to the phrenic motor pools. Ipsilateral hemidiaphragm EMG activity was verified as absent in all mice at 3days post-C2SH. By 2weeks after C2SH, ipsilateral hemidiaphragm EMG activity was present in 39% of vehicle-treated mice compared to 7% of 1NMPP1-treated mice (P=0.03). These data support the hypothesis that BDNF/TrkB signaling involving TrkB kinase activity plays a critical role in spontaneous recovery of diaphragm activity following cervical spinal cord injury.

  7. Activation of TrkB with TAM-163 results in opposite effects on body weight in rodents and non-human primates.

    PubMed

    Perreault, Mylène; Feng, Guo; Will, Sarah; Gareski, Tiffany; Kubasiak, David; Marquette, Kimberly; Vugmeyster, Yulia; Unger, Thaddeus J; Jones, Juli; Qadri, Ariful; Hahm, Seung; Sun, Ying; Rohde, Cynthia M; Zwijnenberg, Raphael; Paulsen, Janet; Gimeno, Ruth E

    2013-01-01

    Strong genetic data link the Tyrosine kinase receptor B (TrkB) and its major endogenous ligand brain-derived neurotrophic factor (BDNF) to the regulation of energy homeostasis, with loss-of-function mutations in either gene causing severe obesity in both mice and humans. It has previously been reported that peripheral administration of the endogenous TrkB agonist ligand neurotrophin-4 (NT-4) profoundly decreases food intake and body weight in rodents, while paradoxically increasing these same parameters in monkeys. We generated a humanized TrkB agonist antibody, TAM-163, and characterized its therapeutic potential in several models of type 2 diabetes and obesity. In vitro, TAM-163 bound to human and rodent TrkB with high affinity, activated all aspects of the TrkB signaling cascade and induced TrkB internalization and degradation in a manner similar to BDNF. In vivo, peripheral administration of TAM-163 decreased food intake and/or body weight in mice, rats, hamsters, and dogs, but increased food intake and body weight in monkeys. The magnitude of weight change was similar in rodents and non-human primates, occurred at doses where there was no appreciable penetration into deep structures of the brain, and could not be explained by differences in exposures between species. Rather, peripherally administered TAM-163 localized to areas in the hypothalamus and the brain stem located outside the blood-brain barrier in a similar manner between rodents and non-human primates, suggesting differences in neuroanatomy across species. Our data demonstrate that a TrkB agonist antibody, administered peripherally, causes species-dependent effects on body weight similar to the endogenous TrkB ligand NT-4. The possible clinical utility of TrkB agonism in treating weight regulatory disorder, such as obesity or cachexia, will require evaluation in man.

  8. Activation of TrkB with TAM-163 Results in Opposite Effects on Body Weight in Rodents and Non-Human Primates

    PubMed Central

    Perreault, Mylène; Feng, Guo; Will, Sarah; Gareski, Tiffany; Kubasiak, David; Marquette, Kimberly; Vugmeyster, Yulia; Unger, Thaddeus J.; Jones, Juli; Qadri, Ariful; Hahm, Seung; Sun, Ying; Rohde, Cynthia M.; Zwijnenberg, Raphael; Paulsen, Janet; Gimeno, Ruth E.

    2013-01-01

    Strong genetic data link the Tyrosine kinase receptor B (TrkB) and its major endogenous ligand brain-derived neurotrophic factor (BDNF) to the regulation of energy homeostasis, with loss-of-function mutations in either gene causing severe obesity in both mice and humans. It has previously been reported that peripheral administration of the endogenous TrkB agonist ligand neurotrophin-4 (NT-4) profoundly decreases food intake and body weight in rodents, while paradoxically increasing these same parameters in monkeys. We generated a humanized TrkB agonist antibody, TAM-163, and characterized its therapeutic potential in several models of type 2 diabetes and obesity. In vitro, TAM-163 bound to human and rodent TrkB with high affinity, activated all aspects of the TrkB signaling cascade and induced TrkB internalization and degradation in a manner similar to BDNF. In vivo, peripheral administration of TAM-163 decreased food intake and/or body weight in mice, rats, hamsters, and dogs, but increased food intake and body weight in monkeys. The magnitude of weight change was similar in rodents and non-human primates, occurred at doses where there was no appreciable penetration into deep structures of the brain, and could not be explained by differences in exposures between species. Rather, peripherally administered TAM-163 localized to areas in the hypothalamus and the brain stem located outside the blood-brain barrier in a similar manner between rodents and non-human primates, suggesting differences in neuroanatomy across species. Our data demonstrate that a TrkB agonist antibody, administered peripherally, causes species-dependent effects on body weight similar to the endogenous TrkB ligand NT-4. The possible clinical utility of TrkB agonism in treating weight regulatory disorder, such as obesity or cachexia, will require evaluation in man. PMID:23700410

  9. Induction of metastatic potential by TrkB via activation of IL6/JAK2/STAT3 and PI3K/AKT signaling in breast cancer

    PubMed Central

    Kim, Min Soo; Lee, Won Sung; Jeong, Joon; Kim, Seong-Jin; Jin, Wook

    2015-01-01

    In metastatic breast cancers, the acquisition of metastatic ability, which leads to clinically incurable disease and poor survival, has been associated with acquisition of epithelial-mesenchymal transition (EMT) program and self-renewing trait (CSCs) via activation of PI3K/AKT and IL6/JAK2/STAT3 signaling pathways. We found that TrkB is a key regulator of PI3K/AKT and JAK/STAT signal pathway-mediated tumor metastasis and EMT program. Here, we demonstrated that TrkB activates AKT by directly binding to c-Src, leading to increased proliferation. Also, TrkB increases Twist-1 and Twist-2 expression through activation of JAK2/STAT3 by inducing c-Src-JAK2 complex formation. Furthermore, TrkB in the absence of c-Src binds directly to JAK2 and inhibits SOCS3-mediated JAK2 degradation, resulting in increased total JAK2 and STAT3 levels, which subsequently leads to JAK2/STAT3 activation and Twist-1 upregulation. Additionally, activation of the JAK2/STAT3 pathway via induction of IL-6 secretion by TrkB enables induction of activation of the EMT program via induction of STAT3 nuclear translocation. These observations suggest that TrkB is a promising target for future intervention strategies to prevent tumor metastasis, EMT program and self-renewing trait in breast cancer. PMID:26515594

  10. Determination of superoxide dismutase mimetic activity in common culinary herbs.

    PubMed

    Chohan, Magali; Naughton, Declan P; Opara, Elizabeth I

    2014-01-01

    Under conditions of oxidative stress, the removal of superoxide, a free radical associated with chronic inflammation, is catalysed by superoxide dismutase (SOD). Thus in addition to acting as an antioxidant, SOD may also be utilized as an anti-inflammatory agent. Some plant derived foods have been shown to have SOD mimetic (SODm) activity however it is not known if this activity is possessed by culinary herbs which have previously been shown to possess both antioxidant and anti-inflammatory properties. The aim of the study was to ascertain if the culinary herbs rosemary, sage and thyme possess SODm activity, and to investigate the influence of cooking and digestion on this activity. Transition metal ion content was also determined to establish if it could likely contribute to any SODm activity detected. All extracts of uncooked (U), cooked (C) and cooked and digested (C&D) herbs were shown to possess SODm activity, which was significantly correlated with previously determined antioxidant and anti-inflammatory activities of these herbs. SODm activity was significantly increased following (C) and (C&D) for rosemary and sage only. The impact of (C) and (C&D) on the SODm for thyme may have been influenced by its transition metal ion content. SODm activity may contribute to the herbs' antioxidant and anti-inflammatory activities however the source and significance of this activity need to be established.

  11. TrkB Activators for the Treatment of Traumatic Vision Loss

    DTIC Science & Technology

    2016-10-01

    Award  Number:    W81XWH-­12-­1-­0436   TITLE:      TrkB  Activators  for  the  Treatment  of  Traumatic  Vision   Loss PRINCIPAL  INVESTIGATOR...REPORT  TYPE Annual   3. DATES  COVERED 30/09/2016- 29/09/2016   4. TITLE  AND  SUBTITLE TrkB  Activators  for  the  Treatment  of  Traumatic  Vision   Loss ...leading  to  functional   loss  of  vision.    There  are  currently  few  treatments  for  such  injuries  that  can  be  deployed  rapidly  in  the

  12. BDNF mediated TrkB activation contributes to the EMT progression and the poor prognosis in human salivary adenoid cystic carcinoma.

    PubMed

    Jia, Sen; Wang, Weixi; Hu, Zhiqiang; Shan, Chun; Wang, Lei; Wu, Baolei; Yang, Zihui; Yang, Xinjie; Lei, Delin

    2015-01-01

    The aim of the present study was to investigate whether the expression of Brain-Derived Neurotrophic Factor (BDNF) and its receptor Tropomyosin-related kinase B (TrkB) is correlated with the clinical progression of salivary adenoid cystic carcinoma (SACC) and whether the BDNF/TrkB axis is associated with the induction of epithelial-mesenchymal transition (EMT) in SACC cells. The expression of BDNF, TrkB, and E-cadherin (an EMT biomarker) in 76 primary SACC specimens and 20 normal salivary gland tissues was analyzed by immunohistochemistry. Additionally, the expression of BDNF, TrkB, and E-cadherin in SACC cell lines (SACC-83 and SACC-LM) was analyzed by RT-PCR and Western blotting. The biological role of the BDNF/TrkB axis in the EMT progression of SACC was evaluated after treatment with increased levels of BDNF and by inhibiting TrkB activity in SACC-83 cell line. The progression of SACC cells through EMT was assessed by RT-PCR, Western blotting, photography, migration and invasion assays. Elevated expression of TrkB (92.1%) and BDNF (89.5%), and downregulated expression of E-cadherin (47.4%) was found in SACC specimens, which was significantly correlated with the invasion and metastasis in SACC (P<0.05). The high expression of TrkB and the low expression of E-cadherin was significantly correlated with the poor prognosis of SACC patients (P<0.05). The expression of TrkB was inversely correlated with the expression of E-cadherin in both SACC cases and cell lines (P<0.05). Increasing BDNF levels after treatment with exogenous recombinant human BDNF (rhBDNF) at 100 ng/ml significantly promoted the activation of TrKB and the progression of EMT in SACC cells. While obstruction of TrkB by its inhibitor, k252a (100 nM), significantly inhibited the EMT progression of SACC cells. These results suggest that BDNF-mediated TrkB activation contributes to the EMT progression and the poor prognosis in SACC. The present study demonstrated that the BDNF/TrkB axis promotes the

  13. Enzyme-mimetic activity of Ce-intercalated titanate nanosheets.

    PubMed

    Kamada, Kai; Soh, Nobuaki

    2015-04-23

    Colloidal solutions of Ce-doped titanate nanosheets (Ce-TNS) with tiny dimensions (<10 nm) were fabricated through a hydrolysis reaction of titanium tetraisopropoxide and Ce(NO3)3, and their annihilation activity for reactive oxygen species (ROS) was investigated. The obtained Ce-TNS had an akin crystal structure to layered tetratitanate (Ti4O9(2-)) and Ce ions occupied interlayer space between the host layers with a negative charge. The Ce-TNS possessed a superoxide dismutase (SOD) mimetic activity for disproportionation of superoxide anion radicals (O2(-)) as target ROS. It was explained that the annihilation of O2(-) caused a valence fluctuation of Ce ions existing in the interlayer. Moreover, the activity of Ce-TNS exceeded that of CeO2 nanoparticles recently attracting much attention as an inorganic SOD mimic. The superior performance was explained mainly by a high dispersion stability of the Ce-TNS bringing about a huge reaction area. Moreover, the Ce-TNS protected DNA molecules from ultraviolet light induced oxidative damage, demonstrating effectiveness as one of the new inorganic protecting agents for biomolecules and tissues.

  14. Autocrine activity of BDNF induced by the STAT3 signaling pathway causes prolonged TrkB activation and promotes human non-small-cell lung cancer proliferation

    PubMed Central

    Chen, Bo; Liang, Yan; He, Zheng; An, Yunhe; Zhao, Weihong; Wu, Jianqing

    2016-01-01

    Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin superfamily, which has been implicated in the pathophysiology of the nervous system. Recently, several studies have suggested that BDNF and/or its receptor, tropomyosin related kinase B (TrkB), are involved in tumor growth and metastasis in several cancers, including prostate cancer, neuroblastoma, pancreatic ductal carcinoma, hepatocellular carcinoma, and lung cancer. Despite the increasing emphasis on BDNF/TrkB signaling in human tumors, how it participates in primary tumors has not yet been determined. Additionally, little is known about the molecular mechanisms that elicit signaling downstream of TrkB in the progression of non-small-cell lung cancer (NSCLC). In this study, we report the significant expression of BDNF in NSCLC samples and show that BDNF stimulation increases the synthesis of BDNF itself through activation of STAT3 in lung cancer cells. The release of BDNF can in turn activate TrkB signaling. The activation of both TrkB and STAT3 contribute to downstream signaling and promote human non-small-cell lung cancer proliferation. PMID:27456333

  15. Mimetics of brain-derived neurotrophic factor loops 1 and 4 are active in a model of ischemic stroke in rats.

    PubMed

    Gudasheva, Tatyana A; Povarnina, Polina; Logvinov, Ilya O; Antipova, Tatyana A; Seredenin, Sergey B

    2016-01-01

    Two dimeric dipeptides, bis-(N-monosuccinyl-l-seryl-l-lysine)hexamethylenediamide (GSB-106) and bis-(N-monosuccinyl-l-methionyl-l-serine) heptamethylenediamide (GSB-214), were designed based on the brain-derived neurotrophic factor (BDNF) loop 4 and loop 1 β-turn sequences, respectively. Earlier, both of these dipeptides were shown to exhibit neuroprotective activity in vitro (10(-5)-10(-8) M). The present study aimed to investigate the mechanisms of action of these peptides and their neuroprotective activity in an experimental stroke model. We used western blot and HT-22 hippocampal neuronal cell line to investigate whether these peptides induced phosphorylation of the TrkB receptor and the AKT and ERK kinases. Rat middle cerebral artery occlusion (MCAO) was used as a stroke model. GSB-106 and GSB-214 were administered intraperitoneally (0.1 mg (1.3×10(-7) mol)/kg) 4 hours after MCAO and daily for 7 days. The cerebral infarct volumes were measured with 2,3,5-triphenyltetrazolium chloride staining 21 days after MCAO. Both compounds were shown to elevate the TrkB phosphorylation level while having different post-receptor signaling patterns. GSB-106 activated the PI3K/AKT and MAPK/ERK pathways simultaneously, whereas GSB-214 activated the PI3K/AKT only. In experimental stroke, the reduction of cerebral infarct volume by GSB-106 (∼66%) was significantly greater than that of GSB-214 (∼28% reduction), which could be explained by the fundamental role of the MAPK/ERK pathway in neurogenesis and neuroplasticity. Notably, between these two dipeptides, only GSB-106 exhibited antidepressant activity, as was found previously. The results provided support for the beneficial pharmacological properties of BDNF loop 4 mimetic GSB-106, thereby suggesting a potential role for this dipeptide as a therapeutic agent.

  16. TrkB activation by 7, 8-dihydroxyflavone increases synapse AMPA subunits and ameliorates spatial memory deficits in a mouse model of Alzheimer's disease.

    PubMed

    Gao, Lei; Tian, Mi; Zhao, Hong-Yun; Xu, Qian-Qian; Huang, Yu-Ming; Si, Qun-Cao; Tian, Qing; Wu, Qing-Ming; Hu, Xia-Min; Sun, Li-Bo; McClintock, Shawn M; Zeng, Yan

    2016-02-01

    We recently demonstrated that activation of tyrosine receptor kinase B (TrkB) by 7, 8-dihydroxyflavone (7, 8-DHF), the selective TrkB agonist, increased surface alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors (AMPARs) AMPA receptor subunit GluR1 (GluA1) subunit expression at the synapses of Fragile X Syndrome mutant mice. This present study investigated the effects of 7, 8-DHF on both memory function and synapse structure in relation to the synapse protein level of AMPARs in the Tg2576 Alzheimer's disease (AD) mouse model. The study found that chronic oral administration of 7, 8-DHF significantly improved spatial memory and minimized dendrite loss in the hippocampus of Tg2576 mice. A key feature of 7, 8-DHF action was the increased expression of both GluA1 and GluA2 at synapses. Interestingly, 7, 8-DHF had no effect on the attenuation of amyloid precursor protein or Aβ exhibiting in the Tg2576 AD brains, yet it activated the phosphorylation of TrkB receptors and its downstream signals including CaMKII, Akt, Erk1/2, and cAMP-response element-binding protein. Importantly, cyclotraxin B (a TrkB inhibitor), U0126 (a Ras-ERK pathway inhibitor), Wortmannin (an Akt phosphorylation inhibitor), and KN-93 (a CaMKII inhibitor) counteracted the enhanced expression and phosphorylation of AMPAR subunits induced by 7, 8-DHF. Collectively, our results demonstrated that 7, 8-DHF acted on TrkB and resolved learning and memory impairments in the absence of reduced amyloid in amyloid precursor protein transgenic mice partially through improved synaptic structure and enhanced synaptic AMPARs. The findings suggest that the application of 7, 8-DHF may be a promising new approach to improve cognitive abilities in AD. We provided extensive data demonstrating that 7, 8-dihydroflavone, the TrkB agonist, improved Tg2576 mice spatial memory. This improvement is correlated with a reversion to normal values of GluA1 and GluA2 AMPA receptor subunits and dendritic

  17. A Monoclonal Antibody TrkB Receptor Agonist as a Potential Therapeutic for Huntington’s Disease

    PubMed Central

    Todd, Daniel; Gowers, Ian; Dowler, Simon J.; Wall, Michael D.; McAllister, George; Fischer, David F.; Dijkstra, Sipke; Fratantoni, Silvina A.; van de Bospoort, Rhea; Veenman-Koepke, Jessica; Flynn, Geraldine; Arjomand, Jamshid; Dominguez, Celia; Munoz-Sanjuan, Ignacio; Wityak, John; Bard, Jonathan A.

    2014-01-01

    Huntington’s disease (HD) is a devastating, genetic neurodegenerative disease caused by a tri-nucleotide expansion in exon 1 of the huntingtin gene. HD is clinically characterized by chorea, emotional and psychiatric disturbances and cognitive deficits with later symptoms including rigidity and dementia. Pathologically, the cortico-striatal pathway is severely dysfunctional as reflected by striatal and cortical atrophy in late-stage disease. Brain-derived neurotrophic factor (BDNF) is a neuroprotective, secreted protein that binds with high affinity to the extracellular domain of the tropomyosin-receptor kinase B (TrkB) receptor promoting neuronal cell survival by activating the receptor and down-stream signaling proteins. Reduced cortical BDNF production and transport to the striatum have been implicated in HD pathogenesis; the ability to enhance TrkB signaling using a BDNF mimetic might be beneficial in disease progression, so we explored this as a therapeutic strategy for HD. Using recombinant and native assay formats, we report here the evaluation of TrkB antibodies and a panel of reported small molecule TrkB agonists, and identify the best candidate, from those tested, for in vivo proof of concept studies in transgenic HD models. PMID:24503862

  18. Optimization of a Small Tropomyosin-related Kinase B (TrkB) Agonist 7,8-Dihydroxyflavone Active in Mouse Models of Depression

    PubMed Central

    Liu, Xia; Chan, Chi-Bun; Qi, Qi; Xiao, Ge; Luo, Hongbo R.; He, Xiaolin; Ye, Keqiang

    2012-01-01

    Structure-activity relationship study shows that the catechol group in 7,8-dihdyroxyflavone, a selective small TrkB receptor agonist, is critical for the agonistic activity. To improve the poor pharmacokinetic profiles intrinsic to catechol-containing molecules and elevate the agonistic effect of the lead compound, we initiated the lead optimization campaign by synthesizing various bioisosteric derivatives. Here we show that the optimized 2-methyl-8-(4′-(pyrrolidin-1-yl)phenyl)chromeno[7,8-d]imidazol-6(1H)-one derivative possesses the enhanced TrkB stimulatory activity. Chronic oral administration of this compound significantly reduces the immobility in forced swim test and tail suspension test, two classical antidepressant behavioral animal models, which is accompanied by robust TrkB activation in hippocampus of mouse brain. Further, in vitro ADMET studies demonstrate that this compound possesses the improved features compared to the previous lead compound. Hence, this optimized compound may act as a promising lead candidate for in-depth drug development for treating various neurological disorders including depression. PMID:22984948

  19. Activity of Potent and Selective Host Defense Peptide Mimetics in Mouse Models of Oral Candidiasis

    PubMed Central

    Ryan, Lisa K.; Freeman, Katie B.; Masso-Silva, Jorge A.; Falkovsky, Klaudia; Aloyouny, Ashwag; Markowitz, Kenneth; Hise, Amy G.; Fatahzadeh, Mahnaz; Scott, Richard W.

    2014-01-01

    There is a strong need for new broadly active antifungal agents for the treatment of oral candidiasis that not only are active against many species of Candida, including drug-resistant strains, but also evade microbial countermeasures which may lead to resistance. Host defense peptides (HDPs) can provide a foundation for the development of such agents. Toward this end, we have developed fully synthetic, small-molecule, nonpeptide mimetics of the HDPs that improve safety and other pharmaceutical properties. Here we describe the identification of several HDP mimetics that are broadly active against C. albicans and other species of Candida, rapidly fungicidal, and active against yeast and hyphal cultures and that exhibit low cytotoxicity for mammalian cells. Importantly, specificity for Candida over commensal bacteria was also evident, thereby minimizing potential damage to the endogenous microbiome which otherwise could favor fungal overgrowth. Three compounds were tested as topical agents in two different mouse models of oral candidiasis and were found to be highly active. Following single-dose administrations, total Candida burdens in tongues of infected animals were reduced up to three logs. These studies highlight the potential of HDP mimetics as a new tool in the antifungal arsenal for the treatment of oral candidiasis. PMID:24752272

  20. Role of phosphate on stability and catalase mimetic activity of cerium oxide nanoparticles.

    PubMed

    Singh, Ragini; Singh, Sanjay

    2015-08-01

    Cerium oxide nanoparticles (CeNPs) have been recently shown to scavenge reactive oxygen and nitrogen species (ROS and RNS) in different experimental model systems. CeNPs (3+) and CeNPs (4+) have been shown to exhibit superoxide dismutase (SOD) and catalase mimetic activity, respectively. Due to their nanoscale dimension, CeNPs are expected to interact with the components of biologically relevant buffers and medium, which could alter their catalytic properties. We have demonstrated earlier that CeNPs (3+) interact with phosphate and lose the SOD activity. However, very little is known about the interaction of CeNPs (4+) with the phosphate and other anions, predominantly present in biological buffers and their effects on the catalase mimetic-activity of these nanoparticles. In this study, we report that catalase mimetic-activity of CeNPs (4+) is resistant to the phosphate anions, pH changes and composition of cell culture media. Given the abundance of phosphate anions in the biological system, it is likely that internalized CeNPs would be influenced by cytoplasmic and nucleoplasmic concentration of phosphate.

  1. Brain ischaemia induces shedding of a BDNF-scavenger ectodomain from TrkB receptors by excitotoxicity activation of metalloproteinases and γ-secretases.

    PubMed

    Tejeda, Gonzalo S; Ayuso-Dolado, Sara; Arbeteta, Raquel; Esteban-Ortega, Gema M; Vidaurre, Oscar G; Díaz-Guerra, Margarita

    2016-04-01

    Stroke remains a leading cause of death and disability in the world with limited therapies available to restrict brain damage or improve functional recovery after cerebral ischaemia. A promising strategy currently under investigation is the promotion of brain-derived neurotrophic factor (BDNF) signalling through tropomyosin-related kinase B (TrkB) receptors, a pathway essential for neuronal survival and function. However, TrkB and BDNF-signalling are impaired by excitotoxicity, a primary pathological process in stroke also associated with neurodegenerative diseases. Pathological imbalance of TrkB isoforms is critical in neurodegeneration and is caused by calpain processing of BDNF high affinity full-length receptor (TrkB-FL) and an inversion of the transcriptional pattern of the Ntrk2 gene, to favour expression of the truncated isoform TrkB-T1 over TrkB-FL. We report here that both TrkB-FL and neuronal TrkB-T1 also undergo ectodomain shedding by metalloproteinases activated after ischaemic injury or excitotoxic damage of cortical neurons. Subsequently, the remaining membrane-bound C-terminal fragments (CTFs) are cleaved by γ-secretases within the transmembrane region, releasing their intracellular domains (ICDs) into the cytosol. Therefore, we identify TrkB-FL and TrkB-T1 as new substrates of regulated intramembrane proteolysis (RIP), a mechanism that highly contributes to TrkB-T1 regulation in ischaemia but is minor for TrkB-FL which is mainly processed by calpain. However, since the secreted TrkB ectodomain acts as a BDNF scavenger and significantly alters BDNF/TrkB signalling, the mechanism of RIP could contribute to neuronal death in excitotoxicity. These results are highly relevant since they reveal new targets for the rational design of therapies to treat stroke and other pathologies with an excitotoxic component.

  2. Neurotrophin receptor TrkB promotes lung adenocarcinoma metastasis

    PubMed Central

    Sinkevicius, Kerstin W.; Kriegel, Christina; Bellaria, Kelly J.; Lee, Jaewon; Lau, Allison N.; Leeman, Kristen T.; Zhou, Pengcheng; Beede, Alexander M.; Fillmore, Christine M.; Caswell, Deborah; Barrios, Juliana; Wong, Kwok-Kin; Sholl, Lynette M.; Schlaeger, Thorsten M.; Bronson, Roderick T.; Chirieac, Lucian R.; Winslow, Monte M.; Haigis, Marcia C.; Kim, Carla F.

    2014-01-01

    Lung cancer is notorious for its ability to metastasize, but the pathways regulating lung cancer metastasis are largely unknown. An in vitro system designed to discover factors critical for lung cancer cell migration identified brain-derived neurotrophic factor, which stimulates cell migration through activation of tropomyosin-related kinase B (TrkB; also called NTRK2). Knockdown of TrkB in human lung cancer cell lines significantly decreased their migratory and metastatic ability in vitro and in vivo. In an autochthonous lung adenocarcinoma model driven by activated oncogenic Kras and p53 loss, TrkB deficiency significantly reduced metastasis. Hypoxia-inducible factor-1 directly regulated TrkB expression, and, in turn, TrkB activated Akt signaling in metastatic lung cancer cells. Finally, TrkB expression was correlated with metastasis in patient samples, and TrkB was detected more often in tumors that did not have Kras or epidermal growth factor receptor mutations. These studies demonstrate that TrkB is an important therapeutic target in metastatic lung adenocarcinoma. PMID:24982195

  3. Activity of antimicrobial peptide mimetics in the oral cavity: II. Activity against periopathogenic biofilms and anti-inflammatory activity.

    PubMed

    Hua, J; Scott, R W; Diamond, G

    2010-12-01

    Whereas periodontal disease is ultimately of bacterial etiology, from multispecies biofilms of gram-negative anaerobic microorganisms, much of the deleterious effects are caused by the resultant epithelial inflammatory response. Hence, development of a treatment that combines anti-biofilm antibiotic activity with anti-inflammatory activity would be of great utility. Antimicrobial peptides (AMPs) such as defensins are naturally occurring peptides that exhibit broad-spectrum activity as well as a variety of immunomodulatory activities. Furthermore, bacteria do not readily develop resistance to these agents. However, clinical studies have suggested that they do not represent optimal candidates for exogenous therapeutic agents. Small-molecule mimetics of these AMPs exhibit similar activities to the parent peptides, in addition to having low toxicity, high stability and low cost. To determine whether AMP mimetics have the potential for treatment of periodontal disease, we examined the activity of one mimetic, mPE, against biofilm cultures of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. Metabolic assays as well as culture and biomass measurement assays demonstrated that mPE exhibits potent activity against biofilm cultures of both species. Furthermore, as little as 2 μg ml(-1) mPE was sufficient to inhibit interleukin-1β-induced secretion of interleukin-8 in both gingival epithelial cells and THP-1 cells. This anti-inflammatory activity is associated with a reduction in activation of nuclear factor-κB, suggesting that mPE can act both as an anti-biofilm agent in an anaerobic environment and as an anti-inflammatory agent in infected tissues.

  4. Prostacyclin receptor-independent inhibition of phospholipase C activity by non-prostanoid prostacyclin mimetics

    PubMed Central

    Chow, Kevin B S; Wong, Yung H; Wise, Helen

    2001-01-01

    Chinese hamster ovary (CHO) cells were transiently transfected with the mouse prostacyclin (mIP) receptor to examine IP agonist-mediated stimulation of [3H]-cyclic AMP and [3H]-inositol phosphate production.The prostacyclin analogues, cicaprost, iloprost, carbacyclin and prostaglandin E1, stimulated adenylyl cyclase activity with EC50 values of 5, 6, 25 and 95 nM, respectively. These IP agonists also stimulated the phospholipase C pathway with 10 – 40 fold lower potency than stimulation of adenylyl cyclase.The non-prostanoid prostacyclin mimetics, octimibate, BMY 42393 and BMY 45778, also stimulated adenylyl cyclase activity, with EC50 values of 219, 166 and 398 nM, respectively, but failed to stimulate [3H]-inositol phosphate production.Octimibate, BMY 42393 and BMY 45778 inhibited iloprost-stimulated [3H]-inositol phosphate production in a non-competitive manner.Activation of the endogenously-expressed P2 purinergic receptor by ATP led to an increase in [3H]-inositol phosphate production which was inhibited by the non-prostanoid prostacyclin mimetics in non-transfected CHO cells. Prostacyclin analogues and other prostanoid receptor ligands failed to inhibit ATP-stimulated [3H]-inositol phosphate production.A comparison between the IP receptor-specific non-prostanoid ONO-1310 and the structurally-related EP3 receptor-specific agonist ONO-AP-324, indicated that the inhibitory effect of non-prostanoids was specific for those compounds known to activate IP receptors.The non-prostanoid prostacyclin mimetics also inhibited phospholipase C activity when stimulated by constitutively-active mutant GαqRC, Gα14RC and Gα16QL transiently expressed in CHO cells. These drugs did not inhibit adenylyl cyclase activity when stimulated by the constitutively-active mutant GαsQL.These results suggest that non-prostanoid prostacyclin mimetics can specifically inhibit [3H]-inositol phosphate production by targeting Gq/11 and/or phospholipase C in CHO cells, and

  5. Molecular Design, Structures, and Activity of Antimicrobial Peptide-Mimetic Polymers

    PubMed Central

    Takahashi, Haruko; Palermo, Edmund F.; Yasuhara, Kazuma; Caputo, Gregory A.

    2014-01-01

    There is an urgent need for new antibiotics which are effective against drug-resistant bacteria without contributing to resistance development. We have designed and developed antimicrobial copolymers with cationic amphiphilic structures based on the mimicry of naturally occurring antimicrobial peptides. These copolymers exhibit potent antimicrobial activity against a broad spectrum of bacteria including methicillin-resistant Staphylococcus aureus with no adverse hemolytic activity. Notably, these polymers also did not result in any measurable resistance development in E. coli. The peptide-mimetic design principle offers significant flexibility and diversity in the creation of new antimicrobial materials and their potential biomedical applications. PMID:23832766

  6. Parvalbumin expression in visual cortical interneurons depends on neuronal activity and TrkB ligands during an Early period of postnatal development.

    PubMed

    Patz, Silke; Grabert, Jochen; Gorba, Thorsten; Wirth, Marcus J; Wahle, Petra

    2004-03-01

    The differentiation of cortical interneurons is controlled by environmental factors. Here, we describe the role of activity and neurotrophins in regulating parvalbumin (PARV) expression using organotypic cultures (OTC) of rat visual cortex as model system. In OTC, PARV expression was dramatically delayed. The organotypic proportion of approximately 6% PARV neurons was not established before 50-70 DIV, whereas in vivo all neurons are present until P20. Thalamic afferents increased cortical PARV mRNA in OTC, but not to the age-matched in vivo level. During the first 10 DIV, BDNF and NT-4 accelerated PARV mRNA expression in a Trk receptor and MEK2 dependent manner. The BDNF action required PI3 kinase signalling. PARV expression required activity. The proportion of neurons which managed to up-regulate PARV was inversely related to the duration of early transient periods of activity deprivation. Long-term activity-deprived OTC completely failed to up-regulate PARV mRNA. Both TrkB ligands failed to promote PARV expression in activity-deprived OTC. However, a few basket and chandelier neurons were observed, suggesting that the development of class-specific morphological features is activity-independent. Once established, PARV expression became resistant to late-onset activity deprivation. In conclusion, PARV expression depended on activity and TrkB ligands which appear to prime the PARV expression already before its developmental onset.

  7. Activity of antimicrobial peptide mimetics in the oral cavity: I. Activity against biofilms of Candida albicans.

    PubMed

    Hua, J; Yamarthy, R; Felsenstein, S; Scott, R W; Markowitz, K; Diamond, G

    2010-12-01

    Naturally occurring antimicrobial peptides hold promise as therapeutic agents against oral pathogens such as Candida albicans but numerous difficulties have slowed their development. Synthetic, non-peptidic analogs that mimic the properties of these peptides have many advantages and exhibit potent, selective antimicrobial activity. Several series of mimetics (with molecular weight < 1000) were developed and screened against oral Candida strains as a proof-of-principle for their antifungal properties. One phenylalkyne and several arylamide compounds with reduced mammalian cytotoxicities were found to be active against C. albicans. These compounds demonstrated rapid fungicidal activity in liquid culture even in the presence of saliva, and demonstrated synergy with standard antifungal agents. When assayed against biofilms grown on denture acrylic, the compounds exhibited potent fungicidal activity as measured by metabolic and fluorescent viability assays. Repeated passages in sub-minimum inhibitory concentration levels did not lead to resistant Candida, in contrast to fluconazole. Our results demonstrate the proof-of principle for the use of these compounds as anti-Candida agents, and their further testing is warranted as novel anti-Candida therapies.

  8. Aging and a peripheral immune challenge interact to reduce mature brain-derived neurotrophic factor and activation of TrkB, PLCgamma1, and ERK in hippocampal synaptoneurosomes.

    PubMed

    Cortese, Giuseppe P; Barrientos, Ruth M; Maier, Steven F; Patterson, Susan L

    2011-03-16

    For reasons that are not well understood, aging significantly increases brain vulnerability to challenging life events. High-functioning older individuals often experience significant cognitive decline after an inflammatory event such as surgery, infection, or injury. We have modeled this phenomenon in rodents and have previously reported that a peripheral immune challenge (intraperitoneal injection of live Escherichia coli) selectively disrupts consolidation of hippocampus-dependent memory in aged (24-month-old), but not young (3-month-old), F344xBN rats. More recently, we have demonstrated that this infection-evoked memory deficit is mirrored by a selective deficit in long-lasting synaptic plasticity in the hippocampus. Interestingly, these deficits occur in forms of long-term memory and synaptic plasticity known to be strongly dependent on brain-derived neurotrophic factor (BDNF). Here, we begin to test the hypothesis that the combination of aging and an infection might disrupt production or processing of BDNF protein in the hippocampus, decreasing the availability of BDNF for plasticity-related processes at synaptic sites. We find that mature BDNF is markedly reduced in Western blots of hippocampal synaptoneurosomes prepared from aged animals following infection. This reduction is blocked by intra-cisterna magna administration of the anti-inflammatory cytokine IL-1Ra (interleukin 1-specific receptor antagonist). Levels of the pan-neurotrophin receptor p75(NTR) and the BDNF receptor TrkB (tropomyosin receptor kinase B) are not significantly altered in these synaptoneurosomes, but phosphorylation of TrkB and downstream activation of PLCγ1 (phospholipase Cγ1) and ERK (extracellular response kinase) are attenuated-observations consistent with reduced availability of mature BDNF to activate TrkB signaling. These data suggest that inflammation-evoked reductions in BDNF at synapses might contribute to inflammation-evoked disruptions in long-term memory and synaptic

  9. A biologically active peptide mimetic of N-acetylgalactosamine/galactose

    PubMed Central

    Eggink, Laura L; Hoober, J Kenneth

    2009-01-01

    Background Glycosylated proteins and lipids are important regulatory factors whose functions can be altered by addition or removal of sugars to the glycan structure. The glycans are recognized by sugar-binding lectins that serve as receptors on the surface of many cells and facilitate initiation of an intracellular signal that changes the properties of the cells. We identified a peptide that mimics the ligand of an N-acetylgalactosamine (GalNAc)-specific lectin and asked whether the peptide would express specific biological activity. Findings A 12-mer phage display library was screened with a GalNAc-specific lectin to identify an amino acid sequence that binds to the lectin. Phage particles that were eluted from the lectin with free GalNAc were considered to have been bound to a GalNAc-binding site. Peptides were synthesized with the selected sequence as a quadravalent structure to facilitate receptor crosslinking. Treatment of human peripheral blood mononuclear cells for 24 h with the peptide stimulated secretion of interleukin-8 (IL-8) but not of IL-1β, IL-6, IL-10, or tumor necrosis factor-α (TNF-α). The secretion of IL-21 was stimulated as strongly with the peptide as with interferon-γ. Conclusion The data indicate that the quadravalent peptide has biological activity with a degree of specificity. These effects occurred at concentrations in the nanomolar range, in contrast to free sugars that generally bind to proteins in the micro- to millimolar range. PMID:19284521

  10. Injury-induced axonal sprouting in the hippocampus is initiated by activation of trkB receptors.

    PubMed

    Dinocourt, Céline; Gallagher, Sandra E; Thompson, Scott M

    2006-10-01

    Penetrating head injuries are often accompanied by the delayed development of post-traumatic epilepsy. Schaffer collateral transection leads to axonal sprouting and hyperexcitability in area CA3 of hippocampal slice cultures. We used this model to test the hypothesis that the injury-induced axonal sprouting results from increased neurotrophin signaling via trkB receptors near the lesion. Using rats and mice, we established that sprouting CA3 pyramidal cell axons are labeled with an antibody to the growth-associated protein GAP-43. We observed two- to threefold increases in the level of brain-derived neurotrophic factor and trkB protein in area CA3 by 24-48 h after Schaffer collateral transection, preceding the onset of axonal sprouting. Finally, we demonstrated that injury-induced axonal sprouting of GAP-43-immunoreactive axons is impaired in hippocampal slice cultures from mice expressing low levels of trkB receptors. We conclude that injury-induced axonal sprouting is initiated by brain-derived neurotrophic factor-trkB signaling and suggest that this process may be critical for the genesis of post-traumatic epilepsy.

  11. Glycosides from Stevia rebaudiana Bertoni Possess Insulin-Mimetic and Antioxidant Activities in Rat Cardiac Fibroblasts

    PubMed Central

    Prata, Cecilia; Zambonin, Laura; Rizzo, Benedetta; Vieceli Dalla Sega, Francesco

    2017-01-01

    Stevia rebaudiana Bertoni is a shrub having a high content of sweet diterpenoid glycosides in its leaves, mainly stevioside and rebaudioside A, which are used as noncaloric, natural sweeteners. The aim of this study was to deepen the knowledge about the insulin-mimetic effect exerted by four different mixtures of steviol glycosides, rich in stevioside and rebaudioside A, in neonatal rat cardiac fibroblasts. The potential antioxidant activity of these steviol glycosides was also assessed, as oxidative stress is associated with diabetes. Likewise the insulin effect, steviol glycosides caused an increase in glucose uptake into rat fibroblasts by activating the PI3K/Akt pathway, thus inducing Glut4 translocation to the plasma membrane. The presence of S961, an insulin antagonist, completely abolished these effects, allowing to hypothesize that steviol glycosides could act as ligands of the same receptor engaged by insulin. Moreover, steviol glycosides counteracted oxidative stress by increasing reduced glutathione intracellular levels and upregulating expression and activity of the two antioxidant enzymes superoxide dismutase and catalase. The present work unravels the insulin-mimetic effect and the antioxidant property exerted by steviol glycosides, suggesting their potential beneficial role in the cotreatment of diabetes and in health maintenance.

  12. An investigation of the mimetic enzyme activity of two-dimensional Pd-based nanostructures.

    PubMed

    Wei, Jingping; Chen, Xiaolan; Shi, Saige; Mo, Shiguang; Zheng, Nanfeng

    2015-12-07

    In this work, we investigated the mimetic enzyme activity of two-dimensional (2D) Pd-based nanostructures (e.g. Pd nanosheets, Pd@Au and Pd@Pt nanoplates) and found that they possess intrinsic peroxidase-, oxidase- and catalase-like activities. These nanostructures were able to activate hydrogen peroxide or dissolved oxygen for catalyzing the oxidation of organic substrates, and decompose hydrogen peroxide to generate oxygen. More systematic investigations revealed that the peroxidase-like activities of these Pd-based nanomaterials were highly structure- and composition-dependent. Among them, Pd@Pt nanoplates displayed the highest peroxidase-like activity. Based on these findings, Pd-based nanostructures were applied for the colorimetric detection of H2O2 and glucose, and also the electro-catalytic reduction of H2O2. This work offers a promising prospect for the application of 2D noble metal nanostructures in biocatalysis.

  13. The Bdnf Val68 to Met Polymorphism Increases Compulsive Alcohol Drinking In Mice Which Is Reversed By TrkB Activation

    PubMed Central

    Warnault, Vincent; Darcq, Emmanuel; Morisot, Nadege; Phamluong, Khanhky; Wilbrecht, Linda; Massa, Stephen M.; Longo, Frank M.; Ron, Dorit

    2015-01-01

    Background The Val66 to Met polymorphism within the brain-derived neurotrophic factor (BDNF) sequence reduces activity-dependent BDNF release, and is associated with psychiatric disorders in humans. Alcoholism is one of the most prevalent psychiatric diseases. Here, we tested the hypothesis that this polymorphism increases the severity of alcohol abuse disorders. Methods We generated transgenic mice carrying the mouse homolog of the human Met66BDNF allele (Met68BDNF), and used alcohol-drinking paradigms in combination with viral-mediated gene delivery and pharmacology. Results We found that Met68BDNF mice consumed excessive amounts of alcohol and continued to drink despite negative consequences, a hallmark of addiction. Importantly, compulsive alcohol intake was reversed by overexpression of the wild-type Val68BDNF allele in the ventromedial prefrontal cortex of the Met68BDNF mice, or by systemic administration of the TrkB agonist, LM22A-4. Conclusions Our findings suggest that carrying the Met66BDNF allele increases the risk of developing uncontrolled and excessive alcohol drinking that can be reversed by directly activating the BDNF receptor, TrkB. Importantly, this work identifies a potential therapeutic strategy for the treatment of compulsive alcohol drinking in humans carrying the Met66BDNF allele. PMID:26204799

  14. Molecular design, structures, and activity of antimicrobial peptide-mimetic polymers.

    PubMed

    Takahashi, Haruko; Palermo, Edmund F; Yasuhara, Kazuma; Caputo, Gregory A; Kuroda, Kenichi

    2013-10-01

    There is an urgent need for new antibiotics which are effective against drug-resistant bacteria without contributing to resistance development. We have designed and developed antimicrobial copolymers with cationic amphiphilic structures based on the mimicry of naturally occurring antimicrobial peptides. These copolymers exhibit potent antimicrobial activity against a broad spectrum of bacteria including methicillin-resistant Staphylococcus aureus with no adverse hemolytic activity. Notably, these polymers also did not result in any measurable resistance development in E. coli. The peptide-mimetic design principle offers significant flexibility and diversity in the creation of new antimicrobial materials and their potential biomedical applications. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Human dendritic cell activation induced by a permannosylated dendron containing an antigenic GM3-lactone mimetic

    PubMed Central

    Rojo, Javier; Ballerini, Clara; Comito, Giuseppina; Nativi, Cristina

    2014-01-01

    Summary Vaccination strategies based on dendritic cells (DCs) armed with specific tumor antigens have been widely exploited due the properties of these immune cells in coordinating an innate and adaptive response. Here, we describe the convergent synthesis of the bifunctional multivalent glycodendron 5, which contains nine residues of mannose for DC targeting and one residue of an immunogenic mimetic of a carbohydrate melanoma associated antigen. The immunological assays demonstrated that the glycodendron 5 is able to induce human immature DC activation in terms of a phenotype expression of co-stimulatory molecules expression and MHCII. Furthermore, DCs activated by the glycodendron 5 stimulate T lymphocytes to proliferate in a mixed lymphocytes reaction (MLR). PMID:24991284

  16. Fe-Co bimetallic alloy nanoparticles as a highly active peroxidase mimetic and its application in biosensing.

    PubMed

    Chen, Yujin; Cao, Haiyan; Shi, Wenbing; Liu, Hong; Huang, Yuming

    2013-06-04

    This article presents a new enzyme-mimic activity of non-noble metal-based bimetallic Fe-Co NPs. This type of enzyme-mimic exhibits much higher affinity to H2O2 over other NPs-based peroxidase mimetics by at least one order of magnitude due to the synergistic effects between the two metals.

  17. Pituitary Adenylate Cyclase-Activating Peptide in the Central Amygdala Causes Anorexia and Body Weight Loss via the Melanocortin and the TrkB Systems

    PubMed Central

    Iemolo, Attilio; Ferragud, Antonio; Cottone, Pietro; Sabino, Valentina

    2015-01-01

    Growing evidence suggests that the pituitary adenylate cyclase-activating polypeptide (PACAP)/PAC1 receptor system represents one of the main regulators of the behavioral, endocrine, and autonomic responses to stress. Although induction of anorexia is a well-documented effect of PACAP, the central sites underlying this phenomenon are poorly understood. The present studies addressed this question by examining the neuroanatomical, behavioral, and pharmacological mechanisms mediating the anorexia produced by PACAP in the central nucleus of the amygdala (CeA), a limbic structure implicated in the emotional components of ingestive behavior. Male rats were microinfused with PACAP (0–1 μg per rat) into the CeA and home-cage food intake, body weight change, microstructural analysis of food intake, and locomotor activity were assessed. Intra-CeA (but not intra-basolateral amygdala) PACAP dose-dependently induced anorexia and body weight loss without affecting locomotor activity. PACAP-treated rats ate smaller meals of normal duration, revealing that PACAP slowed feeding within meals by decreasing the regularity and maintenance of feeding from pellet-to-pellet; postprandial satiety was unaffected. Intra-CeA PACAP-induced anorexia was blocked by coinfusion of either the melanocortin receptor 3/4 antagonist SHU 9119 or the tyrosine kinase B (TrKB) inhibitor k-252a, but not the CRF receptor antagonist D-Phe-CRF(12–41). These results indicate that the CeA is one of the brain areas through which the PACAP system promotes anorexia and that PACAP preferentially lessens the maintenance of feeding in rats, effects opposite to those of palatable food. We also demonstrate that PACAP in the CeA exerts its anorectic effects via local melanocortin and the TrKB systems, and independently from CRF. PMID:25649277

  18. Pituitary Adenylate Cyclase-Activating Peptide in the Central Amygdala Causes Anorexia and Body Weight Loss via the Melanocortin and the TrkB Systems.

    PubMed

    Iemolo, Attilio; Ferragud, Antonio; Cottone, Pietro; Sabino, Valentina

    2015-07-01

    Growing evidence suggests that the pituitary adenylate cyclase-activating polypeptide (PACAP)/PAC1 receptor system represents one of the main regulators of the behavioral, endocrine, and autonomic responses to stress. Although induction of anorexia is a well-documented effect of PACAP, the central sites underlying this phenomenon are poorly understood. The present studies addressed this question by examining the neuroanatomical, behavioral, and pharmacological mechanisms mediating the anorexia produced by PACAP in the central nucleus of the amygdala (CeA), a limbic structure implicated in the emotional components of ingestive behavior. Male rats were microinfused with PACAP (0-1 μg per rat) into the CeA and home-cage food intake, body weight change, microstructural analysis of food intake, and locomotor activity were assessed. Intra-CeA (but not intra-basolateral amygdala) PACAP dose-dependently induced anorexia and body weight loss without affecting locomotor activity. PACAP-treated rats ate smaller meals of normal duration, revealing that PACAP slowed feeding within meals by decreasing the regularity and maintenance of feeding from pellet-to-pellet; postprandial satiety was unaffected. Intra-CeA PACAP-induced anorexia was blocked by coinfusion of either the melanocortin receptor 3/4 antagonist SHU 9119 or the tyrosine kinase B (TrKB) inhibitor k-252a, but not the CRF receptor antagonist D-Phe-CRF(12-41). These results indicate that the CeA is one of the brain areas through which the PACAP system promotes anorexia and that PACAP preferentially lessens the maintenance of feeding in rats, effects opposite to those of palatable food. We also demonstrate that PACAP in the CeA exerts its anorectic effects via local melanocortin and the TrKB systems, and independently from CRF.

  19. Thioredoxin-mimetic peptide CB3 lowers MAPKinase activity in the Zucker rat brain☆

    PubMed Central

    Cohen-Kutner, Moshe; Khomsky, Lena; Trus, Michael; Ben-Yehuda, Hila; Lenhard, James M.; Liang, Yin; Martin, Tonya; Atlas, Daphne

    2014-01-01

    Diabetes is a high risk factor for dementia. High glucose may be a risk factor for dementia even among persons without diabetes, and in transgenic animals it has been shown to cause a potentiation of indices that are pre-symptomatic of Alzheimer's disease. To further elucidate the underlying mechanisms linking inflammatory events elicited in the brain during oxidative stress and diabetes, we monitored the activation of mitogen-activated kinsase (MAPKs), c-jun NH2-terminal kinase (JNK), p38 MAP kinases (p38MAPK), and extracellular activating kinsae1/2 (ERK1/2) and the anti-inflammatory effects of the thioredoxin mimetic (TxM) peptides, Ac-Cys-Pro-Cys-amide (CB3) and Ac-Cys-Gly-Pro-Cys-amide (CB4) in the brain of male leptin-receptor-deficient Zucker diabetic fatty (ZDF) rats and human neuroblastoma SH-SY5Y cells. Daily i.p. injection of CB3 to ZDF rats inhibited the phosphorylation of JNK and p38MAPK, and prevented the expression of thioredoxin-interacting-protein (TXNIP/TBP-2) in ZDF rat brain. Although plasma glucose/insulin remained high, CB3 also increased the phosphorylation of AMP-ribose activating kinase (AMPK) and inhibited p70S6K kinase in the brain. Both CB3 and CB4 reversed apoptosis induced by inhibiting thioredoxin reductase as monitored by decreasing caspase 3 cleavage and PARP dissociation in SH-SY5Y cells. The decrease in JNK and p38MAPK activity in the absence of a change in plasma glucose implies a decrease in oxidative or neuroinflammatory stress in the ZDF rat brain. CB3 not only attenuated MAPK phosphorylation and activated AMPK in the brain, but it also diminished apoptotic markers, most likely acting via the MAPK–AMPK–mTOR pathway. These results were correlated with CB3 and CB4 inhibiting inflammation progression and protection from oxidative stress induced apoptosis in human neuronal cells. We suggest that by attenuating neuro-inflammatory processes in the brain Trx1 mimetic peptides could become beneficial for preventing neurological

  20. Activity of an antimicrobial peptide mimetic against planktonic and biofilm cultures of oral pathogens.

    PubMed

    Beckloff, Nicholas; Laube, Danielle; Castro, Tammy; Furgang, David; Park, Steven; Perlin, David; Clements, Dylan; Tang, Haizhong; Scott, Richard W; Tew, Gregory N; Diamond, Gill

    2007-11-01

    Antimicrobial peptides (AMPs) are naturally occurring, broad-spectrum antimicrobial agents that have recently been examined for their utility as therapeutic antibiotics. Unfortunately, they are expensive to produce and are often sensitive to protease digestion. To address this problem, we have examined the activity of a peptide mimetic whose design was based on the structure of magainin, exhibiting its amphiphilic structure. We demonstrate that this compound, meta-phenylene ethynylene (mPE), exhibits antimicrobial activity at nanomolar concentrations against a variety of bacterial and Candida species found in oral infections. Since Streptococcus mutans, an etiological agent of dental caries, colonizes the tooth surface and forms a biofilm, we quantified the activity of this compound against S. mutans growing under conditions that favor biofilm formation. Our results indicate that mPE can prevent the formation of a biofilm at nanomolar concentrations. Incubation with 5 nM mPE prevents further growth of the biofilm, and 100 nM mPE reduces viable bacteria in the biofilm by 3 logs. Structure-function analyses suggest that mPE inhibits the bioactivity of lipopolysaccharide and binds DNA at equimolar ratios, suggesting that it may act both as a membrane-active molecule, similar to magainin, and as an intracellular antibiotic, similar to other AMPs. We conclude that mPE and similar molecules display great potential for development as therapeutic antimicrobials.

  1. Collagen-binding VEGF mimetic peptide: Structure, matrix interaction, and endothelial cell activation

    NASA Astrophysics Data System (ADS)

    Chan, Tania R.

    Long term survival of artificial tissue constructs depends greatly on proper vascularization. In nature, differentiation of endothelial cells and formation of vasculature are directed by dynamic spatio-temporal cues in the extracellular matrix that are difficult to reproduce in vitro. In this dissertation, we present a novel bifunctional peptide that mimics matrix-bound vascular endothelial growth factor (VEGF), which can be used to encode spatially controlled angiogenic signals in collagen-based scaffolds. The peptide, QKCMP, contains a collagen mimetic domain (CMP) that binds to type I collagen by a unique triple helix hybridization mechanism and a VEGF mimetic domain (QK) with pro-angiogenic activity. We demonstrate QKCMP's ability to hybridize with native and heat denatured collagens through a series of binding studies on collagen and gelatin substrates. Circular dichroism experiments show that the peptide retains the triple helical structure vital for collagen binding, and surface plasmon resonance study confirms the molecular interaction between the peptide and collagen strands. Cell culture studies demonstrate QKCMP's ability to induce endothelial cell morphogenesis and network formation as a matrix-bound factor in 2D and 3D collagen scaffolds. We also show that the peptide can be used to spatially modify collagen-based substrates to promote localized endothelial cell activation and network formation. To probe the biological events that govern these angiogenic cellular responses, we investigated the cell signaling pathways activated by collagen-bound QKCMP and determined short and long-term endothelial cell response profiles for p38, ERK1/2, and Akt signal transduction cascades. Finally, we present our efforts to translate the peptide's in vitro bioactivity to an in vivo burn injury animal model. When implanted at the wound site, QKCMP functionalized biodegradable hydrogels induce enhanced neovascularization in the granulation tissue. The results show QKCMP

  2. Modulation of CD14 and TLR4.MD-2 activities by a synthetic lipid A mimetic

    PubMed Central

    Cighetti, Roberto; Ciaramelli, Carlotta; Sestito, Stefania Enza; Zanoni, Ivan; Kubik, Łukasz; Ardá-Freire, Ana; Calabrese, Valentina; Granucci, Francesca; Jerala, Roman; Martín-Santamaría, Sonsoles; Jiménez-Barbero, Jesus

    2014-01-01

    Monosaccharide lipid A mimetics composed by a glucosamine core linked to two fatty acid chains and bearing one or two phosphates have been synthesized. While compounds 1 and 2, with one phosphate group, were practically inactive in inhibiting LPS-induced TLR4 signaling and cytokine production in HEK-blue™ cells and murine macrophages, compound 3 with two phosphates was found to be active in efficiently inhibiting TLR4 signal in both cell types. The direct interaction of molecule 3 with MD-2 co-receptor has been investigated by means of NMR and molecular modeling/docking analysis. This compound also interacts directly with CD14 receptor, stimulating its internalization by endocytosis. Experiments on macrophages show that the effect on CD14 reinforces the activity on MD-2.TLR4, because compound 3 activity is higher when CD14 is important for TLR4 signaling i,e, at low LPS concentration. The dual MD-2 and CD14 targeting, accompanied by good solubility in water and lack of toxicity, suggests the use of monosaccharide 3 as a lead compound to develop drugs directed against TLR4-related syndromes. PMID:24339336

  3. An investigation of the mimetic enzyme activity of two-dimensional Pd-based nanostructures

    NASA Astrophysics Data System (ADS)

    Wei, Jingping; Chen, Xiaolan; Shi, Saige; Mo, Shiguang; Zheng, Nanfeng

    2015-11-01

    In this work, we investigated the mimetic enzyme activity of two-dimensional (2D) Pd-based nanostructures (e.g. Pd nanosheets, Pd@Au and Pd@Pt nanoplates) and found that they possess intrinsic peroxidase-, oxidase- and catalase-like activities. These nanostructures were able to activate hydrogen peroxide or dissolved oxygen for catalyzing the oxidation of organic substrates, and decompose hydrogen peroxide to generate oxygen. More systematic investigations revealed that the peroxidase-like activities of these Pd-based nanomaterials were highly structure- and composition-dependent. Among them, Pd@Pt nanoplates displayed the highest peroxidase-like activity. Based on these findings, Pd-based nanostructures were applied for the colorimetric detection of H2O2 and glucose, and also the electro-catalytic reduction of H2O2. This work offers a promising prospect for the application of 2D noble metal nanostructures in biocatalysis.In this work, we investigated the mimetic enzyme activity of two-dimensional (2D) Pd-based nanostructures (e.g. Pd nanosheets, Pd@Au and Pd@Pt nanoplates) and found that they possess intrinsic peroxidase-, oxidase- and catalase-like activities. These nanostructures were able to activate hydrogen peroxide or dissolved oxygen for catalyzing the oxidation of organic substrates, and decompose hydrogen peroxide to generate oxygen. More systematic investigations revealed that the peroxidase-like activities of these Pd-based nanomaterials were highly structure- and composition-dependent. Among them, Pd@Pt nanoplates displayed the highest peroxidase-like activity. Based on these findings, Pd-based nanostructures were applied for the colorimetric detection of H2O2 and glucose, and also the electro-catalytic reduction of H2O2. This work offers a promising prospect for the application of 2D noble metal nanostructures in biocatalysis. Electronic supplementary information (ESI) available: TEM images, EDX and dispersion stability of Pd-based nanomaterials

  4. Plasminogen activator inhibitor-1 fused with erythropoietin (EPO) mimetic peptide (EMP) enhances the EPO activity of EMP.

    PubMed

    Kuai, L; Wu, C; Qiu, Q; Zhang, J; Zhou, A; Wang, S; Zhang, H; Song, Q; Liao, S; Han, Y; Liu, J; Ma, Z

    2000-08-01

    Erythropoietin (EPO) mimetic peptide (EMP) encoding sequence was inserted into the gene of plasminogen activator inhibitor-1 (PAI-1) between Ala348 and Pro349 (P2'-P3'), generating a novel gene, PAI-1/EMP (PMP). This was cloned into pET32a expression vector, fused with TrxA peptide in the vector, and a 63-kDa protein was expressed in inclusion bodies with an expression level >50%. The TrxA/PMP protein was purified by Ni-NTA-agarose metal-ligand affinity chromatography to a purity >90%, showing a single, silver-stained band on SDS-PAGE. Using a reticulocyte counting assay, the EPO activity of PMP was determined to be 5,000 IU/mg, 2,500-fold that of EMP.

  5. Self-Assembling Glucagon-Like Peptide 1-Mimetic Peptide Amphiphiles for Enhanced Activity and Proliferation of Insulin-Secreting Cells

    PubMed Central

    Khan, Saahir; Sur, Shantanu; Newcomb, Christina J.; Appelt, Elizabeth A.

    2012-01-01

    Current treatment for type 1 diabetes mellitus requires daily insulin injections that fail to produce physiological glycemic control. Islet cell transplantation has been proposed as a permanent cure but is limited by loss of β-cell viability and function. These limitations could potentially be overcome by relying on the activity of glucagon-like peptide 1 (GLP-1), which acts on β-cells to promote insulin release, proliferation, and survival. We have developed a peptide amphiphile (PA) molecule incorporating a peptide mimetic for GLP-1. This GLP-1-mimetic PA self-assembles into one-dimensional nanofibers that stabilize the active secondary structure of GLP-1 and can be cross-linked by calcium ions to form a macroscopic gel capable of cell encapsulation and 3-dimensional culture. The GLP-1-mimetic PA nanofibers were found to stimulate insulin secretion from rat insulinoma (RINm5f) cells to a significantly greater extent than the mimetic peptide alone and to a level equivalent to that of the clinically used agonist exendin-4. The activity of the GLP-1-mimetic PA is glucose-dependent, lipid-raft dependent, and partially PKA-dependent consistent with native GLP-1. The GLP-1-mimetic PA also completely abrogates inflammatory cytokine-induced cell death to the level of untreated controls. When used as a PA gel to encapsulate RINm5f cells, the GLP-1-mimetic PA stimulates insulin secretion and proliferation in a cytokine-resistant manner that is significantly greater than a non-bioactive PA gel containing exendin-4. Due to its self-assembling property and bioactivity, the GLP-1-mimetic PA can be incorporated into previously developed islet cell transplantation protocols with the potential for significant enhancement of β-cell viability and function. PMID:22342354

  6. Mechanisms of anti-leukemic activity of the Bcl-2 homology domain-3 mimetic S1.

    PubMed

    Liu, Yubo; Li, Zhiqiang; Song, Ting; Xue, Zuguang; Zhang, Zhichao

    2013-09-01

    Most of leukemia exhibits inherent overexpressed Bcl-2-like proteins. Small molecule S1 is a BH3 mimetic discovered by our previous studies. The aim of this study is to dissect the details of apoptosis signaling induced by S1 in acute myeloid leukaemia (AML) cells and to provide a molecular basis for the use of S1 in AML treatment. The anti-leukemic activity of S1 was evaluated in three cultured AML cell lines and eight patient samples. S1 induced apoptosis via an intrinsic apoptosis pathway by the disruption of protein-protein interactions of Bcl-2 family members and triggered the activation of Bax and Bak in AML cells. For the first time, we report that S1 can release pro-apoptotic protein from Bcl-XL and selectively inhibits colony formation of primary AML cells. Bak activation and release determined S1 sensitivity in AML cells. Furthermore, S1-induced apoptosis was largely reduced in cells with shRNA-mediated downregulation of Bak but not Bax. The combination of S1 with PD98059 can inhibit Bcl-2 phosphorylation and enhance Bak release from Bcl-2. Our study identified Bak as a key mediator of S1-induced intrinsic apoptosis in AML cells. Moreover, our data suggest that Bcl-2 phosphorylation plays an anti-apoptotic role in S1-induced apoptosis. This study could contribute not only to the future clinical development of S1, but also the rational use of other pan-Bcl-2 inhibitors, alone or in combination with kinase inhibitor-based strategies. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  7. Smac mimetics induce inflammation and necrotic tumour cell death by modulating macrophage activity

    PubMed Central

    Lecis, D; De Cesare, M; Perego, P; Conti, A; Corna, E; Drago, C; Seneci, P; Walczak, H; Colombo, M P; Delia, D; Sangaletti, S

    2013-01-01

    Smac mimetics (SMs) comprise a class of small molecules that target members of the inhibitor of apoptosis family of pro-survival proteins, whose expression in cancer cells hinders the action of conventional chemotherapeutics. Herein, we describe the activity of SM83, a newly synthesised dimeric SM, in two cancer ascites models: athymic nude mice injected intraperitoneally with IGROV-1 human ovarian carcinoma cells and immunocompetent BALB/c mice injected with murine Meth A sarcoma cells. SM83 rapidly killed ascitic IGROV-1 and Meth A cells in vivo (prolonging mouse survival), but was ineffective against the same cells in vitro. IGROV-1 cells in nude mice were killed within the ascites by a non-apoptotic, tumour necrosis factor (TNF)-dependent mechanism. SM83 administration triggered a rapid inflammatory event characterised by host secretion of TNF, interleukin-1β and interferon-γ. This inflammatory response was associated with the reversion of the phenotype of tumour-associated macrophages from a pro-tumoural M2- to a pro-inflammatory M1-like state. SM83 treatment was also associated with a massive recruitment of neutrophils that, however, was not essential for the antitumoural activity of this compound. In BALB/c mice bearing Meth A ascites, SM83 treatment was in some cases curative, and these mice became resistant to a second injection of cancer cells, suggesting that they had developed an adaptive immune response. Altogether, these results indicate that, in vivo, SM83 modulates the immune system within the tumour microenvironment and, through its pro-inflammatory action, leads cancer cells to die by necrosis with the release of high-mobility group box-1. In conclusion, our work provides evidence that SMs could be more therapeutically active than expected by stimulating the immune system. PMID:24232096

  8. Neuronal activity and TrkB ligands influence Kv3.1b and Kv3.2 expression in developing cortical interneurons.

    PubMed

    Grabert, J; Wahle, P

    2008-10-15

    Among the GABAergic neocortical interneurons, fast-spiking (FS) basket and chandelier cells are essential mediators for feed-forward inhibition, network synchrony and oscillations. The FS properties are in part mediated by the voltage-gated potassium channels Kv3.1b/3.2 which allow the fast repolarization of the membrane necessary for firing non-adapting action potentials at high frequencies. It has been recently reported that the FS phenotype fails to mature in BDNF knockout mice suggesting a role for neurotrophins. We now describe the role of neuronal activity and neurotrophins for Kv3.1b/3.2 expression using organotypic cultures of rat visual cortex as model system. Chronic activity deprivation from 2 days in vitro (DIV) prevented the postnatal developmental increase of Kv3.2, but not Kv3.1b mRNA expression. However, chronic activity deprivation failed to alter Kv3.1b and marginally delayed Kv3.2 protein expression. Activity deprivation by glutamate receptor blockade from 10 to 20 DIV reduced both mRNAs, whereas deprivation with tetrodotoxin (TTX) reduced both mRNAs and the Kv3.2 protein. Thalamic and cortical afferents in cocultures failed to alter the expression. BDNF and NT4 supplemented from 2 DIV onwards increased the expression of Kv3.1b, but not Kv3.2 mRNA in young cultures. Only NT4 increased the expression of both mRNAs later in development. Kv3 protein levels were not changed by exogenous tropomyosin-related kinase B (TrkB) ligands, but the levels decreased upon inhibiting the MAPK signaling suggesting a role for endogenous factors and in particular MEK2 signaling for translation. The results show that Kv3.1b/3.2 expression is differentially controlled by neuronal activity and neurotrophic factors.

  9. Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol).

    PubMed

    Congdon, Thomas R; Notman, Rebecca; Gibson, Matthew I

    2016-09-12

    Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications-from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action.

  10. Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol)

    PubMed Central

    2016-01-01

    Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications—from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action. PMID:27476873

  11. [Investigation of neuroprotective activity of apolipoprotein E peptide mimetic Cog1410 in transgenic lines of Drosophila melanogaster].

    PubMed

    Latypova, E M; Timoshenko, S I; Kislik, G A; Vitek, M; Shvartsman, A L; Sarantseva, S V

    2014-01-01

    The neuroprotective activity of apolipoprotein E (apoE) peptide mimetic Cog1410, containing amino acid sequence of the receptor-binding domain apoE, has been investigated in transgenic lines of Drosophila melanogaster expressing human APP and beta-secretase. Expression of two transgenes caused neuropathological processes attributed to Alzheimer's disease: neurodegeneration, cognitive abnormality and amyloid deposits formation in brain. It was shown that Cog 1410 reduces neurodegeneration in brain of transgenic flies and improves cognitive functions (odor recognition). These data suggest that Cog1410 is a potential neuroprotector that can be used in AD treatment.

  12. Fine-tuning the stimulation of MLL1 methyltransferase activity by a histone H3-based peptide mimetic

    SciTech Connect

    Avdic, Vanja; Zhang, Pamela; Lanouette, Sylvain; Voronova, Anastassia; Skerjanc, Ilona; Couture, Jean-Francois

    2011-08-24

    The SET1 family of methyltransferases carries out the bulk of histone H3 Lys-4 methylation in vivo. One of the common features of this family is the regulation of their methyltransferase activity by a tripartite complex composed of WDR5, RbBP5, and Ash2L. To selectively probe the role of the SET1 family of methyltransferases, we have developed a library of histone H3 peptide mimetics and report herein the characterization of an N{alpha} acetylated form of histone H3 peptide (N{alpha}H3). Binding and inhibition studies reveal that the addition of an acetyl moiety to the N terminus of histone H3 significantly enhances its binding to WDR5 and prevents the stimulation of MLL1 methyltransferase activity by the WDR5-RbBP5-Ash2L complex. The crystal structure of N{alpha}H3 in complex with WDR5 reveals that a high-affinity hydrophobic pocket accommodates the binding of the acetyl moiety. These results provide the structural basis to control WDR5-RbBP5-Ash2L-MLL1 activity and a tool to manipulate stem cell differentiation programs.-Avdic, V., Zhang, P., Lanouette, S., Voronova, A., Skerjanc, I., Couture, J.-F. Fine-tuning the stimulation of MLL1 methyltransferase activity by a histone H3-based peptide mimetic.

  13. Smac Mimetic SM-164 Potentiates APO2L/TRAIL- and Doxorubicin-Mediated Anticancer Activity in Human Hepatocellular Carcinoma Cells

    PubMed Central

    Zhang, Shuijun; Li, Gongquan; Zhao, Yongfu; Liu, Guangzhi; Wang, Yu; Ma, Xiuxian; Li, Dexu; Wu, Yang; Lu, Jianfeng

    2012-01-01

    Background The members of inhibitor of apoptosis proteins (IAPs) family are key negative regulators of apoptosis. Overexpression of IAPs are found in hepatocellular carcinoma (HCC), and can contribute to chemotherapy resistance and recurrence of HCC. Small-molecule Second mitochondria-derived activator of caspases (Smac) mimetics have recently emerged as novel anticancer drugs through targeting IAPs. The specific aims of this study were to 1) examine the anticancer activity of Smac mimetics as a single agent and in combination with chemotherapy in HCC cells, and 2) investigate the mechanism of anticancer action of Smac mimetics. Methods Four HCC cell lines, including SMMC-7721, BEL-7402, HepG2 and Hep3B, and 12 primary HCC cells were used in this study. Smac mimetic SM-164 was used to treat HCC cells. Cell viability, cell death induction and clonal formation assays were used to evaluate the anticancer activity. Western blotting analysis and a pancaspase inhibitor were used to investigate the mechanisms. Results Although SM-164 induced complete cIAP-1 degradation, it displayed weak inhibitory effects on the viability of HCC cells. Nevertheless, SM-164 considerably potentiated Apo2 ligand or TNF-related apoptosis-inducing ligand (APO2L/TRAIL)- and Doxorubicin-mediated anticancer activity in HCC cells. Mechanistic studies demonstrated that SM-164 in combination with chemotherapeutic agents resulted in enhanced activation of caspases-9, -3 and cleavage of poly ADP-ribose polymerase (PARP), and also led to decreased AKT activation. Conclusions Smac mimetics can enhance chemotherapeutic-mediated anticancer activity by enhancing apoptosis signaling and suppressing survival signaling in HCC cells. This study suggests Smac mimetics are potential therapeutic agents for HCC. PMID:23240027

  14. Stage-specific inhibition of TrkB activity leads to long-lasting and sexually dimorphic effects on body weight and hypothalamic gene expression.

    PubMed

    Byerly, Mardi S; Swanson, Roy D; Wong, G William; Blackshaw, Seth

    2013-01-01

    During development, prenatal and postnatal factors program homeostatic set points to regulate food intake and body weight in the adult. Combinations of genetic and environmental factors contribute to the development of neural circuitry that regulates whole-body energy homeostasis. Brain-derived neurotrophic factor (Bdnf) and its receptor, Tyrosine kinase receptor B (TrkB), are strong candidates for mediating the reshaping of hypothalamic neural circuitry, given their well-characterized role in the central regulation of feeding and body weight. Here, we employ a chemical-genetic approach using the TrkB(F616A/F616A) knock-in mouse model to define the critical developmental period in which TrkB inhibition contributes to increased adult fat mass. Surprisingly, transient TrkB inhibition in embryos, preweaning pups, and adults all resulted in long-lasting increases in body weight and fat content. Moreover, sex-specific differences in the effects of TrkB inhibition on both body weight and hypothalamic gene expression were observed at multiple developmental stages. Our results highlight both the importance of the Bdnf/TrkB pathway in maintaining normal body weight throughout life and the role of sex-specific differences in the organization of hypothalamic neural circuitry that regulates body weight.

  15. Ubiquitin C-Terminal Hydrolase L1 (UCH-L1) Promotes Hippocampus-Dependent Memory via Its Deubiquitinating Effect on TrkB.

    PubMed

    Guo, Yun-Yun; Lu, Yi; Zheng, Yuan; Chen, Xiao-Rong; Dong, Jun-Lu; Yuan, Rong-Rong; Huang, Shu-Hong; Yu, Hui; Wang, Yue; Chen, Zhe-Yu; Su, Bo

    2017-06-21

    Multiple studies have established that brain-derived neurotrophic factor (BDNF) plays a critical role in the regulation of synaptic plasticity via its receptor, TrkB. In addition to being phosphorylated, TrkB has also been demonstrated to be ubiquitinated. However, the mechanisms of TrkB ubiquitination and its biological functions remain poorly understood. In this study, we demonstrate that ubiquitin C-terminal hydrolase L1 (UCH-L1) promotes contextual fear conditioning learning and memory via the regulation of ubiquitination of TrkB. We provide evidence that UCH-L1 can deubiquitinate TrkB directly. K460 in the juxtamembane domain of TrkB is the primary ubiquitination site and is regulated by UCH-L1. By using a peptide that competitively inhibits the association between UCH-L1 and TrkB, we show that the blockade of UCH-L1-regulated TrkB deubiquitination leads to increased BDNF-induced TrkB internalization and consequently directs the internalized TrkB to the degradation pathway, resulting in increased degradation of surface TrkB and attenuation of TrkB activation and its downstream signaling pathways. Moreover, injection of the peptide into the DG region of mice impairs hippocampus-dependent memory. Together, our results suggest that the ubiquitination of TrkB is a mechanism that controls its downstream signaling pathways via the regulation of its endocytosis and postendocytic trafficking and that UCH-L1 mediates the deubiquitination of TrkB and could be a potential target for the modulation of hippocampus-dependent memory.SIGNIFICANCE STATEMENT Ubiquitin C-terminal hydrolase L1 (UCH-L1) has been demonstrated to play important roles in the regulation of synaptic plasticity and learning and memory. TrkB, the receptor for brain-derived neurotrophic factor, has also been shown to be a potent regulator of synaptic plasticity. In this study, we demonstrate that UCH-L1 functions as a deubiquitinase for TrkB. The blockage of UCH-L1-regulated deubiquitination of TrkB

  16. Investigation of a Cu(II)-poly(gamma-glutamic acid) complex in aqueous solution and its insulin-mimetic activity.

    PubMed

    Karmaker, Subarna; Saha, Tapan K; Sakurai, Hiromu

    2007-04-10

    The complexation between cupric ions (Cu(II)) and poly(gamma-glutamic acid) (gamma-PGA) in aqueous solutions (pH 3-11) has been studied by UV-visible absorption and electron spin resonance (ESR) techniques. Formation of the Cu(II)-gamma-PGA complex is confirmed by the observation of the blue shift of the absorption band in the visible region, anisotropic line shapes in the ESR spectrum at room temperature, and a computer simulation of the visible absorption spectrum of the complex. The structure of the Cu(II)-gamma-PGA complex, depending on the pH, has been determined. The in vitro insulin-mimetic activity of the Cu(II)-gamma-PGA complex is examined by determining both inhibition of free fatty acid release and glucose uptake in isolated rat adipocytes treated with epinephrine, in which the concentration of the Cu(II)-gamma-PGA complex for 50% inhibition of free fatty acid release is very similar to that of CuSO4. However, it is significantly lower than that of a previously reported insulin-mimetic bis(3-hydroxypicolinato)copper(II), [Cu(3hpic)2], complex.

  17. Circadian variations in expression of the trkB receptor in adult rat hippocampus.

    PubMed

    Dolci, Claudia; Montaruli, Angela; Roveda, Eliana; Barajon, Isabella; Vizzotto, Laura; Grassi Zucconi, Gigliola; Carandente, Franca

    2003-12-19

    The expression of brain-derived neurotrophic factor (BDNF) in the central nervous system (CNS) and the expression of its high-affinity trkB receptor on neuron surfaces are known to depend on neuron activity. The expression of BDNF (mRNA and protein) and trkB mRNA shows circadian oscillations in rat hippocampal homogenates. We investigated circadian variations in trkB expression in specific areas of the adult rat hippocampal formation by immunohistochemistry. In sets of two experiments performed in the spring, 39 2-month-old male Wistar rats were accustomed to a 12-h light-12-h dark cycle for 2 weeks. Three animals were then sacrificed every 4 h. Forty-micrometer-thick coronal sections of hippocampal formation were obtained and processed for trkB immunohistochemistry. Cell staining intensity was assessed by image analysis of different hippocampal areas on five sections per animal. Circadian rhythmicity was evaluated by the cosinor method. Statistically significant circadian variations in trkB expression were found in dentate gyrus, entorhinal cortex, and the CA3 and hilar regions of the hippocampus, with highest expression during the first half of the dark (activity) period. These findings suggest a relationship between trkB expression and the physiological neuronal activation of wakefulness. TrkB receptor expression in the hippocampal regions studied was continuous and changes were gradual over the 24-h cycle, suggesting that more complex regulatory mechanisms also intervened.

  18. TrkB inhibition as a therapeutic target for CNS-related disorders.

    PubMed

    Boulle, Fabien; Kenis, Gunter; Cazorla, Maxime; Hamon, Michel; Steinbusch, Harry W M; Lanfumey, Laurence; van den Hove, Daniel L A

    2012-08-01

    The interaction of brain-derived neurotrophic factor (BDNF) with its tropomyosin-related kinase receptor B (TrkB) is involved in fundamental cellular processes including neuronal proliferation, differentiation and survival as well as neurotransmitter release and synaptic plasticity. TrkB signaling has been widely associated with beneficial, trophic effects and many commonly used psychotropic drugs aim to increase BDNF levels in the brain. However, it is likely that a prolonged increased TrkB activation is observed in many pathological conditions, which may underlie the development and course of clinical symptoms. Interestingly, genetic and pharmacological studies aiming at decreasing TrkB activation in rodent models mimicking human pathology have demonstrated a promising therapeutic landscape for TrkB inhibitors in the treatment of various diseases, e.g. central nervous system (CNS) disorders and several types of cancer. Up to date, only a few selective and potent TrkB inhibitors have been developed. As such, the use of crystallography and in silico approaches to model BDNF-TrkB interaction and to generate relevant pharmacophores represent powerful tools to develop novel compounds targeting the TrkB receptor.

  19. Discovering the enzyme mimetic activity of metal-organic framework (MOF) for label-free and colorimetric sensing of biomolecules.

    PubMed

    Wang, Ying; Zhu, Yingjing; Binyam, Atsebeha; Liu, Misha; Wu, Yinan; Li, Fengting

    2016-12-15

    A label-free sensing strategy based on the enzyme-mimicking activity of MOF was demonstrated for colorimetric detection of biomolecules. Firstly obvious blue color was observed due to the high efficiency of peroxidase-like catalytic activity of Fe-MIL-88A (an ion-based MOF material) toward 3,3',5,5'-tetramethylbenzidine (TMB). Then in the presence of target biomolecule and corresponding aptamer, the mimetic activity of Fe-MIL-88A can be strongly inhibited and used directly to realize the colorimetric detection. On the basis of the interesting findings, we designed a straightforward, label-free and sensitive colorimetric method for biomolecule detection by using the enzyme mimetic property of MOF coupling with molecular recognition element. Compared with the existed publications, our work breaks the routine way by setting up an inorganic-organic MOF-aptamer hybrid platform for colorimetric determination of biomolecules, expanding the targets scope from H2O2 or glucose to biomolecules. As a proof of concept, thrombin and thrombin aptamer was used as a model analyte. The limit of detection of 10nM can be achieved with naked eyes and ultrahigh selectivity of thrombin toward numerous interfering substances with 10-fold concentration was demonstrated significantly. Of note, the method was further applied for the detection of thrombin in human serum samples, showing the results in agreement with those values obtained in an immobilization buffer by the colorimetric method. This inorganic-organic MOF-aptamer sensing strategy may in principle be universally applicable for the detection of a range of environmental or biomedical molecules of interests. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Thrombospondin-1 Mimetic Agonist Peptides Induce Selective Death in Tumor Cells: Design, Synthesis, and Structure-Activity Relationship Studies.

    PubMed

    Denèfle, Thomas; Boullet, Héloise; Herbi, Linda; Newton, Clara; Martinez-Torres, Ana-Carolina; Guez, Alexandre; Pramil, Elodie; Quiney, Claire; Pourcelot, Marilyne; Levasseur, Mikail D; Lardé, Eva; Moumné, Roba; Ogi, François-Xavier; Grondin, Pascal; Merle-Beral, Hélène; Lequin, Olivier; Susin, Santos A; Karoyan, Philippe

    2016-09-22

    Thrombospondin-1 (TSP-1) is a glycoprotein considered as a key actor within the tumor microenvironment. Its binding to CD47, a cell surface receptor, triggers programmed cell death. Previous studies allowed the identification of 4N1K decapeptide derived from the TSP-1/CD47 binding epitope. Here, we demonstrate that this peptide is able to induce selective apoptosis of various cancer cell lines while sparing normal cells. A structure-activity relationship study led to the design of the first serum stable TSP-1 mimetic agonist peptide able to trigger selective programmed cell death (PCD) of at least lung, breast, and colorectal cancer cells. Altogether, these results will be of valuable interest for further investigation in the design of potent CD47 agonist peptides, opening new perspectives for the development of original anticancer therapies.

  1. Bim-BH3 mimetic therapy is effective at suppressing inflammatory arthritis through the activation of myeloid cell apoptosis

    PubMed Central

    Scatizzi, John C.; Hutcheson, Jack; Pope, Richard M.; Firestein, Gary S.; Koch, Alisa E.; Mavers, Melissa; Smason, Avraham; Agrawal, Hemant; Haines, G. Kenneth; Chandel, Navdeep S.; Hotchkiss, Richard S.; Perlman, Harris

    2010-01-01

    Objective Rheumatoid arthritis (RA) is a destructive autoimmune disease characterized by an increased inflammation in the joint. Therapies which activate the apoptotic cascade may have potential as a future therapy for RA, however few therapeutics fit this category. Recently, therapies that mimic the action of Bcl-2 homology 3 (BH3) domain-only proteins such as Bim have shown success in preclinical studies of cancer but their potential in autoimmune disease is unknown. Methods Synovial tissue from RA and osteoarthritis (OA) patients were analyzed for expression of Bim and CD68 using immunohistochemistry. Macrophages from mice lacking (Bim−/−) were examined for response to lipopolysaccharide (LPS) using flow cytometry, real time PCR, ELISA, and immunoblot analysis. Bim−/− mice were stimulated with thioglycollate or LPS and examined for macrophage activation and cytokine production. Experimental arthritis was induced using the K/BxN serum-transfer model. A mimetic peptide corresponding to the BH3 domain of Bim (TAT-BH3) was administered as a prophylactic and as a therapeutic. Edema of the ankles and histopathogical analysis of ankle sections were used to determine severity of arthritis, cellular composition, and apoptosis. Results The expression of Bim was reduced in RA synovial tissue as compared to controls, particularly in macrophages. Bim−/− macrophages displayed elevated expression of markers of inflammation and secreted more IL-1β following stimulation with LPS or thioglycollate. TAT-BH3 ameliorated arthritis development, reduced the number of myeloid cells in the joint, and enhanced apoptosis without inducing cytotoxicity. Conclusion These data demonstrate that BH3 mimetic therapy may have significant potential for RA treatment. PMID:20112357

  2. Cosmology with Mimetic Matter

    SciTech Connect

    Chamseddine, Ali H.; Mukhanov, Viatcheslav; Vikman, Alexander E-mail: viatcheslav.Mukhanov@lmu.de

    2014-06-01

    We consider minimal extensions of the recently proposed Mimetic Dark Matter and show that by introducing a potential for the mimetic non-dynamical scalar field we can mimic nearly any gravitational properties of the normal matter. In particular, the mimetic matter can provide us with inflaton, quintessence and even can lead to a bouncing nonsingular universe. We also investigate the behaviour of cosmological perturbations due to a mimetic matter. We demonstrate that simple mimetic inflation can produce red-tilted scalar perturbations which are largely enhanced over gravity waves.

  3. TrkB signaling is required for behavioral sensitization and conditioned place preference induced by a single injection of cocaine.

    PubMed

    Crooks, Kristy R; Kleven, Daniel T; Rodriguiz, Ramona M; Wetsel, William C; McNamara, James O

    2010-06-01

    Exogenous brain-derived neurotrophic factor (BDNF) can regulate behavioral sensitization and conditioned place preference (CPP) when animals are exposed to repeated cocaine administration. However, it is unclear whether BDNF signaling through the TrkB receptor can mediate these behavioral responses when animals are given a single cocaine exposure. Because TrkB knockout mice die as neonates, we engineered a transgenic mouse that expressed a dominant negative form of TrkB (dnTrkB) in a conditional and reversible manner. We assessed also activation of endogenous TrkB by quantifying levels of phosphorylated TrkB (p-TrkB) in the nucleus accumbens (NAc). We found that a single exposure to cocaine was sufficient to increase p-TrkB within the NAc 9-12h after administration. Expression of the dnTrkB transgene not only prevented the acute cocaine-induced increase in p-TrkB, but it also prevented behavioral sensitization and CPP following a single cocaine injection. These findings demonstrate that TrkB activation is required both for behavioral sensitization and CPP to a single cocaine exposure. The fact that enhanced TrkB activation is induced within 9h of a single injection of cocaine suggests that inhibition of TrkB signaling commencing hours after cocaine exposure may prevent at least the initial antecedents to the sensitizing and reinforcing effects of this psychostimulant. (c) 2010. Published by Elsevier Ltd.

  4. TrkB signaling is required for behavioral sensitization and conditioned place preference induced by a single injection of cocaine

    PubMed Central

    Crooks, Kristy R.; Kleven, Daniel T.; Rodriguiz, Ramona M.; Wetsel, William C.; McNamara, James O.

    2013-01-01

    Exogenous brain-derived neurotrophic factor (BDNF) can regulate behavioral sensitization and conditioned place preference (CPP) when animals are exposed to repeated cocaine administration. However, it is unclear whether BDNF signaling through the TrkB receptor can mediate these behavioral responses when animals are given a single cocaine exposure. Because TrkB knockout mice die as neonates, we engineered a transgenic mouse that expressed a dominant negative form of TrkB (dnTrkB) in a conditional and reversible manner. We assessed also activation of endogenous TrkB by quantifying levels of phosphorylated TrkB (p-TrkB) in the nucleus accumbens (NAc). We found that a single exposure to cocaine was sufficient to increase p-TrkB within the NAc 9–12 h after administration. Expression of the dnTrkB transgene not only prevented the acute cocaine-induced increase in p-TrkB, but it also prevented behavioral sensitization and CPP following a single cocaine injection. These findings demonstrate that TrkB activation is required both for behavioral sensitization and CPP to a single cocaine exposure. The fact that enhanced TrkB activation is induced within 9 h of a single injection of cocaine suggests that inhibition of TrkB signaling commencing hours after cocaine exposure may prevent at least the initial antecedents to the sensitizing and reinforcing effects of this psychostimulant. PMID:20176040

  5. Transient Inhibition of TrkB Kinase Following Status Epilepticus Prevents Development of Temporal Lobe Epilepsy

    PubMed Central

    Liu, Gumei; Gu, Bin; He, Xiao-Ping; Joshi, Rasesh B.; Wackerle, Harold D.; Rodriguiz, Ramona Marie; Wetsel, William C.; McNamara, James O.

    2013-01-01

    Summary Temporal lobe epilepsy is the most common and often devastating form of human epilepsy. The molecular mechanism underlying the development of temporal lobe epilepsy remains largely unknown. Emerging evidence suggests that activation of the BDNF receptor, TrkB, promotes epileptogenesis caused by status epilepticus. We investigated a mouse model in which a brief episode of status epilepticus results in chronic recurrent seizures, anxiety-like behavior, and destruction of hippocampal neurons. We used a chemical-genetic approach to selectively inhibit activation of TrkB. We demonstrate that inhibition of TrkB commencing after status epilepticus and continued for two weeks prevents recurrent seizures, ameliorates anxiety-like behavior, and limits loss of hippocampal neurons when tested weeks to months later. That transient inhibition commencing after status epilepticus can prevent these long-lasting devastating consequences establishes TrkB signaling as an attractive target for developing preventive treatments of epilepsy in humans. PMID:23790754

  6. A TrkB Small Molecule Partial Agonist Rescues TrkB Phosphorylation Deficits and Improves Respiratory Function in a Mouse Model of Rett Syndrome

    PubMed Central

    Schmid, Danielle; Yang, Tao; Ogier, Michael; Adams, Ian; Mirakhur, Yatin; Wang, Qifang; Massa, Stephen M.; Longo, Frank M.; Katz, David M.

    2012-01-01

    Rett syndrome (RTT) results from loss-of-function mutations in the gene encoding the methyl-CpG-binding protein 2 (MeCP2) and is characterized by abnormal motor, respiratory and autonomic control, cognitive impairment, autistic-like behaviors and increased risk of seizures. RTT patients and Mecp2 null mice exhibit reduced expression of Brain-Derived Neurotrophic Factor (BDNF), which has been linked in mice to increased respiratory frequency, a hallmark of RTT. The present study was undertaken to test the hypotheses that BDNF deficits in Mecp2 mutants are associated with reduced activation of the BDNF receptor, TrkB, and that pharmacologic activation of TrkB would improve respiratory function. We characterized BDNF protein expression, TrkB activation and respiration in heterozygous female Mecp2 mutant mice (Het), a model that recapitulates the somatic mosaicism for mutant Mecp2 found in typical RTT patients, and evaluated the ability of a small molecule TrkB agonist, LM22A-4, to ameliorate biochemical and functional abnormalities in these animals. We found that Het mice exhibit 1) reduced BDNF expression and TrkB activation in the medulla and pons and 2) breathing dysfunction, characterized by increased frequency due to periods of tachypnea, and increased apneas, as in RTT patients. Treatment of Het mice with LM22A-4 for 4 weeks rescued wildtype levels of TrkB phosphorylation in the medulla and pons and restored wildtype breathing frequency. These data provide new insight into the role of BDNF signaling deficits in the pathophysiology of RTT and highlight TrkB as a possible therapeutic target in this disease. PMID:22302819

  7. A TrkB small molecule partial agonist rescues TrkB phosphorylation deficits and improves respiratory function in a mouse model of Rett syndrome.

    PubMed

    Schmid, Danielle A; Yang, Tao; Ogier, Michael; Adams, Ian; Mirakhur, Yatin; Wang, Qifang; Massa, Stephen M; Longo, Frank M; Katz, David M

    2012-02-01

    Rett syndrome (RTT) results from loss-of-function mutations in the gene encoding the methyl-CpG-binding protein 2 (MeCP2) and is characterized by abnormal motor, respiratory and autonomic control, cognitive impairment, autistic-like behaviors and increased risk of seizures. RTT patients and Mecp2-null mice exhibit reduced expression of brain-derived neurotrophic factor (BDNF), which has been linked in mice to increased respiratory frequency, a hallmark of RTT. The present study was undertaken to test the hypotheses that BDNF deficits in Mecp2 mutants are associated with reduced activation of the BDNF receptor, TrkB, and that pharmacologic activation of TrkB would improve respiratory function. We characterized BDNF protein expression, TrkB activation and respiration in heterozygous female Mecp2 mutant mice (Het), a model that recapitulates the somatic mosaicism for mutant MECP2 found in typical RTT patients, and evaluated the ability of a small molecule TrkB agonist, LM22A-4, to ameliorate biochemical and functional abnormalities in these animals. We found that Het mice exhibit (1) reduced BDNF expression and TrkB activation in the medulla and pons and (2) breathing dysfunction, characterized by increased frequency due to periods of tachypnea, and increased apneas, as in RTT patients. Treatment of Het mice with LM22A-4 for 4 weeks rescued wild-type levels of TrkB phosphorylation in the medulla and pons and restored wild-type breathing frequency. These data provide new insight into the role of BDNF signaling deficits in the pathophysiology of RTT and highlight TrkB as a possible therapeutic target in this disease.

  8. Requirement of TrkB for synapse elimination in developing cerebellar Purkinje cells

    PubMed Central

    Bosman, Laurens W. J.; Hartmann, Jana; Barski, Jaroslaw J.; Lepier, Alexandra; Noll-Hussong, Michael; Reichardt, Louis F.; Konnerth, Arthur

    2009-01-01

    The receptor tyrosine kinase TrkB and its ligands, brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT-4/5), are critically important for growth, survival and activity-dependent synaptic strengthening in the central nervous system. These TrkB-mediated actions occur in a highly cell-type specific manner. Here we report that cerebellar Purkinje cells, which are richly endowed with TrkB receptors, develop a normal morphology in trkB-deficient mice. Thus, in contrast to other types of neurons, Purkinje cells do not need TrkB for dendritic growth and spine formation. Instead, we find a moderate delay in the maturation of GABAergic synapses and, more importantly, an abnormal multiple climbing fiber innervation in Purkinje cells in trkB-deficient mice. Thus, our results demonstrate an involvement of TrkB receptors in synapse elimination and reveal a new role for receptor tyrosine kinases in the brain. PMID:17940915

  9. Complexes of hydroxy(thio)pyrone and hydroxy(thio)pyridinone with Zn(II) and Mo(VI). Thermodynamic stability and insulin-mimetic activity.

    PubMed

    Chaves, Sílvia; Jelic, Ratomir; Mendonça, Catarina; Carrasco, Marta; Yoshikawa, Yutaka; Sakurai, Hiromu; Santos, M Amélia

    2010-03-01

    The development of metal-containing pharmaceuticals as insulin-mimetics has been the object of recent worldwide research. We have examined a series of zinc(II) and molybdenum(VI) complexes with model O,S-donor ligands (thiomaltol and 1,2-dimethyl-3-hydroxypyridine-4-thione (DMHTP)) and the corresponding O,O-analogues (maltol and DMHP) for their insulin-mimetic activity. Aimed at getting structure-activity relationships, some physical-chemical properties were also studied, such as metal-complex formation, speciation at different pH conditions and ligand lipophilicity. The Zn-complexes exhibit considerably higher insulin-mimetic activity than the corresponding Mo-analogues. Particularly, the bis(thiomaltolato)zinc(II) complex reveals a very high activity, ascribed to the effect of the thione π character and to the soft nature of the sulfur donor atom enhancing the Zn(II)-ligand affinity and the ligand/complex lipophilicity, two determinant parameters for delivering the metal-drug into the cells. Hence, these preliminary studies indicate that the Zn(thiomaltol)₂ complex can be considered a potential drug candidate for treatment of diabetes mellitus, upon in vivo evaluations.

  10. The novel protein kinase C epsilon isoform at the adult neuromuscular synapse: location, regulation by synaptic activity-dependent muscle contraction through TrkB signaling and coupling to ACh release.

    PubMed

    Obis, Teresa; Besalduch, Núria; Hurtado, Erica; Nadal, Laura; Santafe, Manel M; Garcia, Neus; Tomàs, Marta; Priego, Mercedes; Lanuza, Maria A; Tomàs, Josep

    2015-02-10

    Protein kinase C (PKC) regulates a variety of neural functions, including neurotransmitter release. Although various PKC isoforms can be expressed at the synaptic sites and specific cell distribution may contribute to their functional diversity, little is known about the isoform-specific functions of PKCs in neuromuscular synapse. The present study is designed to examine the location of the novel isoform nPKCε at the neuromuscular junction (NMJ), their synaptic activity-related expression changes, its regulation by muscle contraction, and their possible involvement in acetylcholine release. We use immunohistochemistry and confocal microscopy to demonstrate that the novel isoform nPKCε is exclusively located in the motor nerve terminals of the adult rat NMJ. We also report that electrical stimulation of synaptic inputs to the skeletal muscle significantly increased the amount of nPKCε isoform as well as its phosphorylated form in the synaptic membrane, and muscle contraction is necessary for these nPKCε expression changes. The results also demonstrate that synaptic activity-induced muscle contraction promotes changes in presynaptic nPKCε through the brain-derived neurotrophic factor (BDNF)-mediated tyrosine kinase receptor B (TrkB) signaling. Moreover, nPKCε activity results in phosphorylation of the substrate MARCKS involved in actin cytoskeleton remodeling and related with neurotransmission. Finally, blocking nPKCε with a nPKCε-specific translocation inhibitor peptide (εV1-2) strongly reduces phorbol ester-induced ACh release potentiation, which further indicates that nPKCε is involved in neurotransmission. Together, these results provide a mechanistic insight into how synaptic activity-induced muscle contraction could regulate the presynaptic action of the nPKCε isoform and suggest that muscle contraction is an important regulatory step in TrkB signaling at the NMJ.

  11. Structural basis of activation-dependent binding of ligand-mimetic antibody AL-57 to integrin LFA-1

    SciTech Connect

    Zhang, Hongmin; Liu, Jin-huan; Yang, Wei; Springer, Timothy; Shimaoka, Motomu; Wang, Jia-huai

    2010-09-21

    The activity of integrin LFA-1 ({alpha}{sub L}{beta}{sub 2}) to its ligand ICAM-1 is regulated through the conformational changes of its ligand-binding domain, the I domain of {alpha}{sub L} chain, from an inactive, low-affinity closed form (LA), to an intermediate-affinity form (IA), and then finally, to a high-affinity open form (HA). A ligand-mimetic human monoclonal antibody AL-57 (activated LFA-1 clone 57) was identified by phage display to specifically recognize the affinity-upregulated I domain. Here, we describe the crystal structures of the Fab fragment of AL-57 in complex with IA, as well as in its unligated form. We discuss the structural features conferring AL-57's strong selectivity for the high affinity, open conformation of the I domain. The AL-57-binding site overlaps the ICAM-1 binding site on the I domain. Furthermore, an antibody Asp mimics an ICAM Glu by forming a coordination to the metal-ion dependent adhesion site (MIDAS). The structure also reveals better shape complementarity and a more hydrophobic interacting interface in AL-57 binding than in ICAM-1 binding. The results explain AL-57's antagonistic mimicry of LFA-1's natural ligands, the ICAM molecules.

  12. Allosteric activation of protein phosphatase 2C by D-chiro-inositol-galactosamine, a putative mediator mimetic of insulin action.

    PubMed

    Brautigan, D L; Brown, M; Grindrod, S; Chinigo, G; Kruszewski, A; Lukasik, S M; Bushweller, J H; Horal, M; Keller, S; Tamura, S; Heimark, D B; Price, J; Larner, A N; Larner, J

    2005-08-23

    Insulin-stimulated glucose disposal in skeletal muscle proceeds predominantly through a nonoxidative pathway with glycogen synthase as a rate-limiting enzyme, yet the mechanisms for insulin activation of glycogen synthase are not understood despite years of investigation. Isolation of putative insulin second messengers from beef liver yielded a pseudo-disaccharide consisting of pinitol (3-O-methyl-d-chiro-inositol) beta-1,4 linked to galactosamine chelated with Mn(2+) (called INS2). Here we show that chemically synthesized INS2 has biological activity that significantly enhances insulin reduction of hyperglycemia in streptozotocin diabetic rats. We used computer modeling to dock INS2 onto the known three-dimensional crystal structure of protein phosphatase 2C (PP2C). Modeling and FlexX/CScore energy minimization predicted a unique favorable site on PP2C for INS2 in a surface cleft adjacent to the catalytic center. Binding of INS2 is predicted to involve formation of multiple H-bonds, including one with residue Asp163. Wild-type PP2C activity assayed with a phosphopeptide substrate was potently stimulated in a dose-dependent manner by INS2. In contrast, the D163A mutant of PP2C was not activated by INS2. The D163A mutant and wild-type PP2C in the absence of INS2 had the same Mn(2+)-dependent phosphatase activity with p-nitrophenyl phosphate as a substrate, showing that this mutation did not disrupt the catalytic site. We propose that INS2 allosterically activates PP2C, fulfilling the role of a putative mediator mimetic of insulin signaling to promote protein dephosphorylation and metabolic responses.

  13. Structural characterization of the GSK-3beta active site using selective and non-selective ATP-mimetic inhibitors.

    PubMed

    Bertrand, J A; Thieffine, S; Vulpetti, A; Cristiani, C; Valsasina, B; Knapp, S; Kalisz, H M; Flocco, M

    2003-10-17

    GSK-3beta is a regulatory serine/threonine kinase with a plethora of cellular targets. Consequently, selective small molecule inhibitors of GSK-3beta may have a variety of therapeutic uses including the treatment of neurodegenerative diseases, type II diabetes and cancer. In order to characterize the active site of GSK-3beta, we determined crystal structures of unphosphorylated GSK-3beta in complex with selective and non-selective ATP-mimetic inhibitors. Analysis of the inhibitors' interactions with GSK-3beta in the structures reveals how the enzyme can accommodate a number of diverse molecular scaffolds. In addition, a conserved water molecule near Thr138 is identified that can serve a functional role in inhibitor binding. Finally, a comparison of the interactions made by selective and non-selective inhibitors highlights residues on the edge of the ATP binding-site that can be used to obtain inhibitor selectivity. Information gained from these structures provides a promising route for the design of second-generation GSK-3beta inhibitors.

  14. In vitro anti-human immunodeficiency virus (HIV) activities of transition state mimetic HIV protease inhibitors containing allophenylnorstatine.

    PubMed Central

    Kageyama, S; Mimoto, T; Murakawa, Y; Nomizu, M; Ford, H; Shirasaka, T; Gulnik, S; Erickson, J; Takada, K; Hayashi, H

    1993-01-01

    Transition state mimetic tripeptide human immunodeficiency virus (HIV) protease inhibitors containing allophenylnorstatine [(2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid] were synthesized and tested for activity against HIV in vitro. Two compounds, KNI-227 and KNI-272, which were highly potent against HIV protease with little inhibition of other aspartic proteases, showed the most potent activity against the infectivity and cytopathic effect of a wide spectrum of HIV strains. As tested in target CD4+ ATH8 cells, the 50% inhibitory concentrations of KNI-227 against HIV type 1 LAI (HIV-1LAI), HIV-1RF, HIV-1MN, and HIV-2ROD were 0.1, 0.02, 0.03, and 0.1 microM, respectively, while those of KNI-272 were 0.1, 0.02, 0.04, and 0.1 microM, respectively. Both agents completely blocked the replication of 3'-azido-2',3'-dideoxythymidine-sensitive and -insensitive clinical HIV-1 isolates at 0.08 microM as tested in target phytohemagglutinin-activated peripheral blood mononuclear cells. The ratios of 50% cytotoxic concentrations to 50% inhibitory concentrations for KNI-227 and KNI-272 were approximately 2,500 and > 4,000, respectively, as assessed in peripheral blood mononuclear cells. Both compounds blocked the posttranslational cleavage of the p55 precursor protein to generate the mature p24 Gag protein in stably HIV-1-infected cells. The n-octanol-water partition coefficients of KNI-227 and KNI-272 were high, with log Po/w values of 3.79 and 3.56, respectively. Degradation of KNI-227 and KNI-272 in the presence of pepsin (1 mg/ml, pH 2.2) at 37 degrees C for 24 h was negligible. Current data warrant further careful investigations toward possible clinical application of these two novel compounds. Images PMID:8494379

  15. Iron oxide superparamagnetic nanoparticles conjugated with a conformationally blocked α-Tn antigen mimetic for macrophage activation

    NASA Astrophysics Data System (ADS)

    Manuelli, Massimo; Fallarini, Silvia; Lombardi, Grazia; Sangregorio, Claudio; Nativi, Cristina; Richichi, Barbara

    2014-06-01

    Among new therapies to fight tumors, immunotherapy is still one of the most promising and intriguing. Thanks to the ongoing structural elucidation of several tumor antigens and the development of innovative antigen carriers, immunotherapy is in constant evolution and it is largely used either alone or in synergy with chemotherapy/radiotherapy. With the aim to develop fully synthetic immunostimulants we have recently developed a mimetic of the α-Tn mucin antigen, a relevant tumor antigen. The 4C1 blocked mimetic 1, unique example of an α-Tn mimetic antigen, was functionalized with an ω-phosphonate linker and used to decorate iron oxide superparamagnetic nanoparticles (MNPs), employed as multivalent carriers. MNPs, largely exploited for supporting and carrying biomolecules, like antibodies, drugs or antigens, consent to combine in the same nanometric system the main features of an inorganic magnetic core with a bioactive organic coating. The superparamagnetic glyconanoparticles obtained, named GMNPs, are indeed biocompatible and immunoactive, and they preserve suitable characteristics for use as heat mediators in the magnetic fluid hyperthermia (MFH) treatment of tumors. All together these properties make GMNPs attracting devices for innovative tumor treatment.Among new therapies to fight tumors, immunotherapy is still one of the most promising and intriguing. Thanks to the ongoing structural elucidation of several tumor antigens and the development of innovative antigen carriers, immunotherapy is in constant evolution and it is largely used either alone or in synergy with chemotherapy/radiotherapy. With the aim to develop fully synthetic immunostimulants we have recently developed a mimetic of the α-Tn mucin antigen, a relevant tumor antigen. The 4C1 blocked mimetic 1, unique example of an α-Tn mimetic antigen, was functionalized with an ω-phosphonate linker and used to decorate iron oxide superparamagnetic nanoparticles (MNPs), employed as multivalent

  16. Pro-apoptotic activity of BH3-only proteins and BH3 mimetics: from theory to potential cancer therapy.

    PubMed

    Hartman, Mariusz L; Czyz, Malgorzata

    2012-10-01

    The evasion of cancer cells from the induction of cell death pathways results in the resistance of tumor to current treatment modalities. Therefore, the resistance to cell death, one of the hallmarks of cancer, is a major target in the development of new approaches to selectively affect cancer cells. The complex interplay between individual members of Bcl-2 family regulates both cell survival and the mitochondrial pathway of apoptosis by maintaining mitochondrial membrane integrity (anti-apoptotic Bcl-2 subfamily) and by triggering its disruption in response to stress stimuli (Bax-like subfamily). BH3-only proteins, another Bcl-2 subfamily, act either by direct stimulation of pro-apoptotic proteins of the Bax subfamily or by interfering with anti-apoptotic proteins of the Bcl-2 subfamily. Thus, pro-apoptotic BH3 mimetics, thought to function as BH3-only proteins, are expected to improve the effectiveness of cancer treatment. BH3 mimetics could be either natural or synthetic, peptidic or only based on a helical peptide-like scaffold. Experimental and clinical evidence indicates that BH3 mimetics may not be sufficient to cure cancer patients when used as a single agent. BH3 profiling of cancer cells was introduced to better predict the in vivo responsiveness of tumor to BH3 mimetics combined with conventional therapies. In summary, targeting the Bcl-2 proteins is a promising tool with potential to generate new treatment modalities and to complement existing anti-cancer therapies. This review presents the current knowledge on BH3-only proteins and the spectrum of strategies employing BH3 mimetics in preclinical and clinical studies that aim at tumor targeting.

  17. Activation of silenced tumor suppressor genes in prostate cancer cells by a novel energy restriction-mimetic agent.

    PubMed

    Lin, Hsiang-Yu; Kuo, Yi-Chiu; Weng, Yu-I; Lai, I-Lu; Huang, Tim H-M; Lin, Shuan-Pei; Niu, Dau-Ming; Chen, Ching-Shih

    2012-12-01

    Targeting tumor metabolism by energy restriction-mimetic agents (ERMAs) has emerged as a strategy for cancer therapy/prevention. Evidence suggests a mechanistic link between ERMA-mediated antitumor effects and epigenetic gene regulation. Microarray analysis showed that a novel thiazolidinedione-derived ERMA, CG-12, and glucose deprivation could suppress DNA methyltransferase (DNMT)1 expression and reactivate DNA methylation-silenced tumor suppressor genes in LNCaP prostate cancer cells. Thus, we investigated the effects of a potent CG-12 derivative, CG-5, vis-à-vis 2-deoxyglucose, glucose deprivation and/or 5-aza-deoxycytidine, on DNMT isoform expression (Western blotting, RT-PCR), DNMT1 transcriptional activation (luciferase reporter assay), and expression of genes frequently hypermethylated in prostate cancer (quantitative real-time PCR). Promoter methylation was assessed by pyrosequencing analysis. SiRNA-mediated knockdown and ectopic expression of DNMT1 were used to validate DNMT1 as a target of CG-5. CG-5 and glucose deprivation upregulated the expression of DNA methylation-silenced tumor suppressor genes, including GADD45a, GADD45b, IGFBP3, LAMB3, BASP1, GPX3, and GSTP1, but also downregulated methylated tumor/invasion-promoting genes, including CD44, S100A4, and TACSTD2. In contrast, 5-aza-deoxycytidine induced global reactivation of these genes. CG-5 mediated these epigenetic effects by transcriptional repression of DNMT1, which was associated with reduced expression of Sp1 and E2F1. SiRNA-mediated knockdown and ectopic expression of DNMT1 corroborated DNMT1's role in the modulation of gene expression by CG-5. Pyrosequencing revealed differential effects of CG-5 versus 5-aza-deoxycytidine on promoter methylation in these genes. These findings reveal a previously uncharacterized epigenetic effect of ERMAs on DNA methylation-silenced tumor suppressor genes, which may foster novel strategies for prostate cancer therapy. Copyright © 2012 Wiley Periodicals

  18. Spatial cognition and neuro-mimetic navigation: a model of hippocampal place cell activity.

    PubMed

    Arleo, A; Gerstner, W

    2000-09-01

    A computational model of hippocampal activity during spatial cognition and navigation tasks is presented. The spatial representation in our model of the rat hippocampus is built on-line during exploration via two processing streams. An allothetic vision-based representation is built by unsupervised Hebbian learning extracting spatio-temporal properties of the environment from visual input. An idiothetic representation is learned based on internal movement-related information provided by path integration. On the level of the hippocampus, allothetic and idiothetic representations are integrated to yield a stable representation of the environment by a population of localized overlapping CA3-CA1 place fields. The hippocampal spatial representation is used as a basis for goal-oriented spatial behavior. We focus on the neural pathway connecting the hippocampus to the nucleus accumbens. Place cells drive a population of locomotor action neurons in the nucleus accumbens. Reward-based learning is applied to map place cell activity into action cell activity. The ensemble action cell activity provides navigational maps to support spatial behavior. We present experimental results obtained with a mobile Khepera robot.

  19. Allosteric Activation of a G Protein-coupled Receptor with Cell-penetrating Receptor Mimetics*

    PubMed Central

    Zhang, Ping; Leger, Andrew J.; Baleja, James D.; Rana, Rajashree; Corlin, Tiffany; Nguyen, Nga; Koukos, Georgios; Bohm, Andrew; Covic, Lidija; Kuliopulos, Athan

    2015-01-01

    G protein-coupled receptors (GPCRs) are remarkably versatile signaling systems that are activated by a large number of different agonists on the outside of the cell. However, the inside surface of the receptors that couple to G proteins has not yet been effectively modulated for activity or treatment of diseases. Pepducins are cell-penetrating lipopeptides that have enabled chemical and physical access to the intracellular face of GPCRs. The structure of a third intracellular (i3) loop agonist, pepducin, based on protease-activated receptor-1 (PAR1) was solved by NMR and found to closely resemble the i3 loop structure predicted for the intact receptor in the on-state. Mechanistic studies revealed that the pepducin directly interacts with the intracellular H8 helix region of PAR1 and allosterically activates the receptor through the adjacent (D/N)PXXYYY motif through a dimer-like mechanism. The i3 pepducin enhances PAR1/Gα subunit interactions and induces a conformational change in fluorescently labeled PAR1 in a very similar manner to that induced by thrombin. As pepducins can potentially be made to target any GPCR, these data provide insight into the identification of allosteric modulators to this major drug target class. PMID:25934391

  20. Mimetics of caloric restriction include agonists of lipid-activated nuclear receptors.

    PubMed

    Corton, J Christopher; Apte, Udayan; Anderson, Steven P; Limaye, Pallavi; Yoon, Lawrence; Latendresse, John; Dunn, Corrie; Everitt, Jeffrey I; Voss, Kenneth A; Swanson, Cynthia; Kimbrough, Carie; Wong, Jean S; Gill, Sarjeet S; Chandraratna, Roshantha A S; Kwak, Mi-Kyoung; Kensler, Thomas W; Stulnig, Thomas M; Steffensen, Knut R; Gustafsson, Jan-Ake; Mehendale, Harihara M

    2004-10-29

    The obesity epidemic in industrialized countries is associated with increases in cardiovascular disease (CVD) and certain types of cancer. In animal models, caloric restriction (CR) suppresses these diseases as well as chemical-induced tissue damage. These beneficial effects of CR overlap with those altered by agonists of nuclear receptors (NR) under control of the fasting-responsive transcriptional co-activator, peroxisome proliferator-activated co-activator 1alpha (PGC-1alpha). In a screen for compounds that mimic CR effects in the liver, we found statistically significant overlaps between the CR transcript profile in wild-type mice and the profiles altered by agonists of lipid-activated NR, including peroxisome proliferator-activated receptor alpha (PPARalpha), liver X receptor, and their obligate heterodimer partner, retinoid X receptor. The overlapping genes included those involved in CVD (lipid metabolism and inflammation) and cancer (cell fate). Based on this overlap, we hypothesized that some effects of CR are mediated by PPARalpha. As determined by transcript profiling, 19% of all gene expression changes in wild-type mice were dependent on PPARalpha, including Cyp4a10 and Cyp4a14, involved in fatty acid omega-oxidation, acute phase response genes, and epidermal growth factor receptor but not increases in PGC-1alpha. CR protected the livers of wild-type mice from damage induced by thioacetamide, a liver toxicant and hepatocarcinogen. CR protection was lost in PPARalpha-null mice due to inadequate tissue repair. These results demonstrate that PPARalpha mediates some of the effects of CR and indicate that a pharmacological approach to mimicking many of the beneficial effects of CR may be possible.

  1. [Artificial ribonucleases: quantitative analysis of the structure-activity relationship and new insight into the strategy of design of highly efficient RNase mimetics].

    PubMed

    Koroleva, L S; Kuz'min, V E; Muratov, E N; Artemenko, A G; Sil'nikov, V N

    2008-01-01

    The dependence of hydrolytic activity of artificial ribonucleases toward an HIV-I RNA fragment, a 21-mer oligonucleotide, and tRNA Asp on the structure of the RNase mimetic was analyzed. The quantitative structure-activity relationship (QSAR task) was determined by the method of simplex representation of the molecular structure where the amounts of four-atom fragments (simplexes) of fixed structure, symmetry, and chirality served as descriptors. Not only the types of atoms participating in simplexes but also their physicochemical properties (e.g., partial charges, lipophilicities, etc.) were taken into account. This allowed the estimation of the relative role of various factors affecting the interaction of molecules under study with the corresponding biological target. The 2D QSAR models obtained by the method of projection to latent structures have quite satisfactory statistical indices (R2 = 0.82-0.96; Q2 = 0.73-0.89), which help predict the activities of new compounds. The electrostatic properties of ribonuclease atoms were shown to contribute significantly to the manifestation of the hydrolytic activity of ribonucleases in the case of the 21-mer oligonucleotide and tRNA. In addition, the structural fragments that most greatly contribute to the alteration of the hydrolytic activity of RNases were identified. The models obtained were used for the virtual screening and molecular design of new highly efficient RNase mimetics.

  2. Insight into the mechanism revealing the peroxidase mimetic catalytic activity of quaternary CuZnFeS nanocrystals: colorimetric biosensing of hydrogen peroxide and glucose.

    PubMed

    Dalui, Amit; Pradhan, Bapi; Thupakula, Umamahesh; Khan, Ali Hossain; Kumar, Gundam Sandeep; Ghosh, Tanmay; Satpati, Biswarup; Acharya, Somobrata

    2015-05-21

    Artificial enzyme mimetics have attracted immense interest recently because natural enzymes undergo easy denaturation under environmental conditions restricting practical usefulness. We report for the first time chalcopyrite CuZnFeS (CZIS) alloyed nanocrystals (NCs) as novel biomimetic catalysts with efficient intrinsic peroxidase-like activity. Novel peroxidase activities of CZIS NCs have been evaluated by catalytic oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). CZIS NCs demonstrate the synergistic effect of elemental composition and photoactivity towards peroxidase-like activity. The quaternary CZIS NCs show enhanced intrinsic peroxidase-like activity compared to the binary NCs with the same constituent elements. Intrinsic peroxidase-like activity has been correlated with the energy band position of CZIS NCs extracted using scanning tunneling spectroscopy and ultraviolet photoelectron spectroscopy. Kinetic analyses indicate Michaelis-Menten enzyme kinetic model catalytic behavior describing the rate of the enzymatic reaction by correlating the reaction rate with substrate concentration. Typical color reactions arising from the catalytic oxidation of TMB over CZIS NCs with H2O2 have been utilized to establish a simple and sensitive colorimetric assay for detection of H2O2 and glucose. CZIS NCs are recyclable catalysts showing high efficiency in multiple uses. Our study may open up the possibility of designing new photoactive multi-component alloyed NCs as enzyme mimetics in biotechnology applications.

  3. Braneworld mimetic cosmology

    NASA Astrophysics Data System (ADS)

    Sadeghnezhad, Naser; Nozari, Kourosh

    2017-06-01

    We extend the idea of mimetic gravity to a Randall-Sundrum II braneworld model. As for the 4-dimensional mimetic gravity, we isolate the conformal degree of freedom of 5-dimensional gravity in a covariant manner. We assume the bulk metric to be made up of a non-dynamical scalar field Φ and an auxiliary metric G˜AB so that GAB =G˜CDΦ,CΦ,DG˜AB where A , B , . . . are the bulk spacetime indices. Then we show that the induced conformal degree of freedom on the brane as an induced scalar field, plays the role of a mimetic field on the brane. In fact, we suppose that the scalar degree of freedom which mimics the dark sectors on the brane has its origin on the bulk scalar field, Φ. By adopting some suitable mimetic potentials on the brane, we show that this brane mimetic field explains the late time cosmic expansion in the favor of observational data: the equation of state parameter of this field crosses the cosmological constant line in near past from quintessence to phantom phase in a redshift well in the range of observation. We show also that this induced mimetic scalar field has the capability to explain initial time cosmological inflation. We study parameter space of the models numerically in order to constraint the models with Planck2015 data set.

  4. Vitamin C blocks inflammatory platelet-activating factor mimetics created by cigarette smoking.

    PubMed Central

    Lehr, H A; Weyrich, A S; Saetzler, R K; Jurek, A; Arfors, K E; Zimmerman, G A; Prescott, S M; McIntyre, T M

    1997-01-01

    Cigarette smoking within minutes induces leukocyte adhesion to the vascular wall and formation of intravascular leukocyte-platelet aggregates. We find this is inhibited by platelet-activating factor (PAF) receptor antagonists, and correlates with the accumulation of PAF-like mediators in the blood of cigarette smoke-exposed hamsters. These mediators were PAF-like lipids, formed by nonenzymatic oxidative modification of existing phospholipids, that were distinct from biosynthetic PAF. These PAF-like lipids induced isolated human monocytes and platelets to aggregate, which greatly increased their secretion of IL-8 and macrophage inflammatory protein-1alpha. Both events were blocked by a PAF receptor antagonist. Similarly, blocking the PAF receptor in vivo blocked smoke-induced leukocyte aggregation and pavementing along the vascular wall. Dietary supplementation with the antioxidant vitamin C prevented the accumulation of PAF-like lipids, and it prevented cigarette smoke-induced leukocyte adhesion to the vascular wall and formation of leukocyte-platelet aggregates. This is the first in vivo demonstration of inflammatory phospholipid oxidation products and it suggests a molecular mechanism coupling cigarette smoke with rapid inflammatory changes. Inhibition of PAF-like lipid formation and their intravascular sequela by vitamin C suggests a simple dietary means to reduce smoking-related cardiovascular disease. PMID:9153277

  5. Significant In Vivo Anti-Inflammatory Activity of Pytren4Q-Mn a Superoxide Dismutase 2 (SOD2) Mimetic Scorpiand-Like Mn (II) Complex

    PubMed Central

    Serena, Carolina; Calvo, Enrique; Clares, Mari Paz; Diaz, María Luisa; Chicote, Javier U.; Beltrán-Debon, Raúl; Fontova, Ramón; Rodriguez, Alejandro; García-España, Enrique; García-España, Antonio

    2015-01-01

    Background The clinical use of purified SOD enzymes has strong limitations due to their large molecular size, high production cost and immunogenicity. These limitations could be compensated by using instead synthetic SOD mimetic compounds of low molecular weight. Background/Methodology We have recently reported that two SOD mimetic compounds, the MnII complexes of the polyamines Pytren2Q and Pytren4Q, displayed high antioxidant activity in bacteria and yeast. Since frequently molecules with antioxidant properties or free-radical scavengers also have anti-inflammatory properties we have assessed the anti-inflammatory potential of Pytren2Q and Pytren4Q MnII complexes, in cultured macrophages and in a murine model of inflammation, by measuring the degree of protection they could provide against the cellular injury produced by lipopolisacharide, a bacterial endotoxin. Principal Findings In this report we show that the MnII complex of Pytren4Q but not that of Pytren2Q effectively protected human cultured THP-1 macrophages and whole mice from the inflammatory effects produced by LPS. These results obtained with two molecules that are isomers highlight the importance of gathering experimental data from animal models of disease in assessing the potential of candidate molecules. Conclusion/Significance The effective anti-inflammatory activity of the MnII complex of Pytren4Q in addition to its low toxicity, water solubility and ease of production would suggest it is worth taking into consideration for future pharmacological studies. PMID:25742129

  6. Systemic Delivery of a Brain-Penetrant TrkB Antagonist Reduces Cocaine Self-Administration and Normalizes TrkB Signaling in the Nucleus Accumbens and Prefrontal Cortex.

    PubMed

    Verheij, Michel M M; Vendruscolo, Leandro F; Caffino, Lucia; Giannotti, Giuseppe; Cazorla, Maxime; Fumagalli, Fabio; Riva, Marco A; Homberg, Judith R; Koob, George F; Contet, Candice

    2016-08-03

    Cocaine exposure alters brain-derived neurotrophic factor (BDNF) expression in the brain. BDNF signaling through TrkB receptors differentially modulates cocaine self-administration, depending on the brain regions involved. In the present study, we determined how brain-wide inhibition of TrkB signaling affects cocaine intake, the motivation for the drug, and reinstatement of drug taking after extinction. To overcome the inability of TrkB ligands to cross the blood-brain barrier, the TrkB antagonist cyclotraxin-B was fused to the nontoxic transduction domain of the tat protein from human immunodeficiency virus type 1 (tat-cyclotraxin-B). Intravenous injection of tat-cyclotraxin-B dose-dependently reduced cocaine intake, motivation for cocaine (as measured under a progressive ratio schedule of reinforcement), and reinstatement of cocaine taking in rats allowed either short or long access to cocaine self-administration. In contrast, the treatment did not affect operant responding for a highly palatable sweet solution, demonstrating that the effects of tat-cyclotraxin-B are specific for cocaine reinforcement. Cocaine self-administration increased TrkB signaling and activated the downstream Akt pathway in the nucleus accumbens, and had opposite effects in the prefrontal cortex. Pretreatment with tat-cyclotraxin-B normalized protein levels in these two dopamine-innervated brain regions. Cocaine self-administration also increased TrkB signaling in the ventral tegmental area, where the dopaminergic projections originate, but pretreatment with tat-cyclotraxin-B did not alter this effect. Altogether, our data show that systemic administration of a brain-penetrant TrkB antagonist leads to brain region-specific effects and may be a potential pharmacological strategy for the treatment of cocaine addiction. Brain-derived neurotrophic factor (BDNF) signaling through TrkB receptors plays a well established role in cocaine reinforcement. However, local manipulation of BDNF signaling

  7. Systemic Delivery of a Brain-Penetrant TrkB Antagonist Reduces Cocaine Self-Administration and Normalizes TrkB Signaling in the Nucleus Accumbens and Prefrontal Cortex

    PubMed Central

    Vendruscolo, Leandro F.; Caffino, Lucia; Giannotti, Giuseppe; Cazorla, Maxime; Fumagalli, Fabio; Riva, Marco A.; Homberg, Judith R.; Koob, George F.; Contet, Candice

    2016-01-01

    Cocaine exposure alters brain-derived neurotrophic factor (BDNF) expression in the brain. BDNF signaling through TrkB receptors differentially modulates cocaine self-administration, depending on the brain regions involved. In the present study, we determined how brain-wide inhibition of TrkB signaling affects cocaine intake, the motivation for the drug, and reinstatement of drug taking after extinction. To overcome the inability of TrkB ligands to cross the blood–brain barrier, the TrkB antagonist cyclotraxin-B was fused to the nontoxic transduction domain of the tat protein from human immunodeficiency virus type 1 (tat-cyclotraxin-B). Intravenous injection of tat-cyclotraxin-B dose-dependently reduced cocaine intake, motivation for cocaine (as measured under a progressive ratio schedule of reinforcement), and reinstatement of cocaine taking in rats allowed either short or long access to cocaine self-administration. In contrast, the treatment did not affect operant responding for a highly palatable sweet solution, demonstrating that the effects of tat-cyclotraxin-B are specific for cocaine reinforcement. Cocaine self-administration increased TrkB signaling and activated the downstream Akt pathway in the nucleus accumbens, and had opposite effects in the prefrontal cortex. Pretreatment with tat-cyclotraxin-B normalized protein levels in these two dopamine-innervated brain regions. Cocaine self-administration also increased TrkB signaling in the ventral tegmental area, where the dopaminergic projections originate, but pretreatment with tat-cyclotraxin-B did not alter this effect. Altogether, our data show that systemic administration of a brain-penetrant TrkB antagonist leads to brain region-specific effects and may be a potential pharmacological strategy for the treatment of cocaine addiction. SIGNIFICANCE STATEMENT Brain-derived neurotrophic factor (BDNF) signaling through TrkB receptors plays a well established role in cocaine reinforcement. However, local

  8. Mimetic finite difference method

    NASA Astrophysics Data System (ADS)

    Lipnikov, Konstantin; Manzini, Gianmarco; Shashkov, Mikhail

    2014-01-01

    The mimetic finite difference (MFD) method mimics fundamental properties of mathematical and physical systems including conservation laws, symmetry and positivity of solutions, duality and self-adjointness of differential operators, and exact mathematical identities of the vector and tensor calculus. This article is the first comprehensive review of the 50-year long history of the mimetic methodology and describes in a systematic way the major mimetic ideas and their relevance to academic and real-life problems. The supporting applications include diffusion, electromagnetics, fluid flow, and Lagrangian hydrodynamics problems. The article provides enough details to build various discrete operators on unstructured polygonal and polyhedral meshes and summarizes the major convergence results for the mimetic approximations. Most of these theoretical results, which are presented here as lemmas, propositions and theorems, are either original or an extension of existing results to a more general formulation using polyhedral meshes. Finally, flexibility and extensibility of the mimetic methodology are shown by deriving higher-order approximations, enforcing discrete maximum principles for diffusion problems, and ensuring the numerical stability for saddle-point systems.

  9. Ultratrace Naked-Eye Colorimetric Detection of Hg(2+) in Wastewater and Serum Utilizing Mercury-Stimulated Peroxidase Mimetic Activity of Reduced Graphene Oxide-PEI-Pd Nanohybrids.

    PubMed

    Zhang, Shouting; Zhang, Dongxu; Zhang, Xuehong; Shang, Denghui; Xue, Zhonghua; Shan, Duoliang; Lu, Xiaoquan

    2017-03-21

    Herein, we developed a general strategy for rapid, highly selective, and ultratrace naked-eye colorimetric detection of Hg(2+) in aqueous solutions. Two dimensional rGO/PEI/Pd nanohybrids, where rGO, PEI, and Pd were referred to as reduced graphene oxide, polyethylenimine, and Pd nanoparticles, respectively, were synthesized and used as mimetic peroxidase for selective and ultrasensitive detection of Hg(2+) in water and human serum samples. In the presence of mercury ions, the peroxidase mimetic activity of rGO/PEI/Pd nanohybrids was found to be stimulated and enhanced significantly, which promoted the effective oxidation and color change of 3,3',5,5'-tetramethylbenzidine (TMB) in solution to dark blue that was detected by the naked-eye and the absorption spectroscopic method. The proposed sensing strategy coupled with spectroscopic detection method showed an ultralow detection limit of 0.39 nM for Hg(2+) in ddH2O and ∼1 nM in wastewater as well as serum samples, respectively. On the basis of the colorimetric assay, a minimum concentration of ∼10 nM for Hg(2+) in wastewater and human serum can be detected with the naked-eye. The naked-eye-based colorimetric assay for sensitive and selective detection of mercury is expected to hold huge potentials in applications such as environmental monitoring, clinical diagnosis, and pharmaceutical analysis.

  10. Distinct requirements for TrkB and TrkC signaling in target innervation by sensory neurons

    NASA Technical Reports Server (NTRS)

    Postigo, Antonio; Calella, Anna Maria; Fritzsch, Bernd; Knipper, Marlies; Katz, David; Eilers, Andreas; Schimmang, Thomas; Lewin, Gary R.; Klein, Rudiger; Minichiello, Liliana

    2002-01-01

    Signaling by brain-derived neurotrophic factor (BDNF) via the TrkB receptor, or by neurotrophin-3 (NT3) through the TrkC receptor support distinct populations of sensory neurons. The intracellular signaling pathways activated by Trk (tyrosine kinase) receptors, which in vivo promote neuronal survival and target innervation, are not well understood. Using mice with TrkB or TrkC receptors lacking the docking site for Shc adaptors (trkB(shc/shc) and trkC(shc/shc) mice), we show that TrkB and TrkC promote survival of sensory neurons mainly through Shc site-independent pathways, suggesting that these receptors use similar pathways to prevent apoptosis. In contrast, the regulation of target innervation appears different: in trkB(shc/shc) mice neurons lose target innervation, whereas in trkC(shc/shc) mice the surviving TrkC-dependent neurons maintain target innervation and function. Biochemical analysis indicates that phosphorylation at the Shc site positively regulates autophosphorylation of TrkB, but not of TrkC. Our findings show that although TrkB and TrkC signals mediating survival are largely similar, TrkB and TrkC signals required for maintenance of target innervation in vivo are regulated by distinct mechanisms.

  11. Distinct requirements for TrkB and TrkC signaling in target innervation by sensory neurons

    PubMed Central

    Postigo, Antonio; Calella, Anna Maria; Fritzsch, Bernd; Knipper, Marlies; Katz, David; Eilers, Andreas; Schimmang, Thomas; Lewin, Gary R.; Klein, Rüdiger; Minichiello, Liliana

    2002-01-01

    Signaling by brain-derived neurotrophic factor (BDNF) via the TrkB receptor, or by neurotrophin-3 (NT3) through the TrkC receptor support distinct populations of sensory neurons. The intracellular signaling pathways activated by Trk (tyrosine kinase) receptors, which in vivo promote neuronal survival and target innervation, are not well understood. Using mice with TrkB or TrkC receptors lacking the docking site for Shc adaptors (trkBshc/shc and trkCshc/shc mice), we show that TrkB and TrkC promote survival of sensory neurons mainly through Shc site-independent pathways, suggesting that these receptors use similar pathways to prevent apoptosis. In contrast, the regulation of target innervation appears different: in trkBshc/shc mice neurons lose target innervation, whereas in trkCshc/shc mice the surviving TrkC-dependent neurons maintain target innervation and function. Biochemical analysis indicates that phosphorylation at the Shc site positively regulates autophosphorylation of TrkB, but not of TrkC. Our findings show that although TrkB and TrkC signals mediating survival are largely similar, TrkB and TrkC signals required for maintenance of target innervation in vivo are regulated by distinct mechanisms. PMID:11877382

  12. Distinct requirements for TrkB and TrkC signaling in target innervation by sensory neurons

    NASA Technical Reports Server (NTRS)

    Postigo, Antonio; Calella, Anna Maria; Fritzsch, Bernd; Knipper, Marlies; Katz, David; Eilers, Andreas; Schimmang, Thomas; Lewin, Gary R.; Klein, Rudiger; Minichiello, Liliana

    2002-01-01

    Signaling by brain-derived neurotrophic factor (BDNF) via the TrkB receptor, or by neurotrophin-3 (NT3) through the TrkC receptor support distinct populations of sensory neurons. The intracellular signaling pathways activated by Trk (tyrosine kinase) receptors, which in vivo promote neuronal survival and target innervation, are not well understood. Using mice with TrkB or TrkC receptors lacking the docking site for Shc adaptors (trkB(shc/shc) and trkC(shc/shc) mice), we show that TrkB and TrkC promote survival of sensory neurons mainly through Shc site-independent pathways, suggesting that these receptors use similar pathways to prevent apoptosis. In contrast, the regulation of target innervation appears different: in trkB(shc/shc) mice neurons lose target innervation, whereas in trkC(shc/shc) mice the surviving TrkC-dependent neurons maintain target innervation and function. Biochemical analysis indicates that phosphorylation at the Shc site positively regulates autophosphorylation of TrkB, but not of TrkC. Our findings show that although TrkB and TrkC signals mediating survival are largely similar, TrkB and TrkC signals required for maintenance of target innervation in vivo are regulated by distinct mechanisms.

  13. Exploring the Molecular Interactions of 7,8-Dihydroxyflavone and Its Derivatives with TrkB and VEGFR2 Proteins

    PubMed Central

    Chitranshi, Nitin; Gupta, Vivek; Kumar, Sanjay; Graham, Stuart L.

    2015-01-01

    7,8-Dihydroxyflavone (7,8-DHF) is a TrkB receptor agonist, and treatment with this flavonoid derivative brings about an enhanced TrkB phosphorylation and promotes downstream cellular signalling. Flavonoids are also known to exert an inhibitory effect on the vascular endothelial growth factor receptor (VEGFR) family of tyrosine kinase receptors. VEGFR2 is one of the important receptors involved in the regulation of vasculogenesis and angiogenesis and has also been implicated to exhibit various neuroprotective roles. Its upregulation and uncontrolled activity is associated with a range of pathological conditions such as age-related macular degeneration and various proliferative disorders. In this study, we investigated molecular interactions of 7,8-DHF and its derivatives with both the TrkB receptor as well as VEGFR2. Using a combination of molecular docking and computational mapping tools involving molecular dynamics approaches we have elucidated additional residues and binding energies involved in 7,8-DHF interactions with the TrkB Ig2 domain and VEGFR2. Our investigations have revealed for the first time that 7,8-DHF has dual biochemical action and its treatment may have divergent effects on the TrkB via its extracellular Ig2 domain and on the VEGFR2 receptor through the intracellular kinase domain. Contrary to its agonistic effects on the TrkB receptor, 7,8-DHF was found to downregulate VEGFR2 phosphorylation both in 661W photoreceptor cells and in retinal tissue. PMID:26404256

  14. Insight into the mechanism revealing the peroxidase mimetic catalytic activity of quaternary CuZnFeS nanocrystals: colorimetric biosensing of hydrogen peroxide and glucose

    NASA Astrophysics Data System (ADS)

    Dalui, Amit; Pradhan, Bapi; Thupakula, Umamahesh; Khan, Ali Hossain; Kumar, Gundam Sandeep; Ghosh, Tanmay; Satpati, Biswarup; Acharya, Somobrata

    2015-05-01

    Artificial enzyme mimetics have attracted immense interest recently because natural enzymes undergo easy denaturation under environmental conditions restricting practical usefulness. We report for the first time chalcopyrite CuZnFeS (CZIS) alloyed nanocrystals (NCs) as novel biomimetic catalysts with efficient intrinsic peroxidase-like activity. Novel peroxidase activities of CZIS NCs have been evaluated by catalytic oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). CZIS NCs demonstrate the synergistic effect of elemental composition and photoactivity towards peroxidase-like activity. The quaternary CZIS NCs show enhanced intrinsic peroxidase-like activity compared to the binary NCs with the same constituent elements. Intrinsic peroxidase-like activity has been correlated with the energy band position of CZIS NCs extracted using scanning tunneling spectroscopy and ultraviolet photoelectron spectroscopy. Kinetic analyses indicate Michaelis-Menten enzyme kinetic model catalytic behavior describing the rate of the enzymatic reaction by correlating the reaction rate with substrate concentration. Typical color reactions arising from the catalytic oxidation of TMB over CZIS NCs with H2O2 have been utilized to establish a simple and sensitive colorimetric assay for detection of H2O2 and glucose. CZIS NCs are recyclable catalysts showing high efficiency in multiple uses. Our study may open up the possibility of designing new photoactive multi-component alloyed NCs as enzyme mimetics in biotechnology applications.Artificial enzyme mimetics have attracted immense interest recently because natural enzymes undergo easy denaturation under environmental conditions restricting practical usefulness. We report for the first time chalcopyrite CuZnFeS (CZIS) alloyed nanocrystals (NCs) as novel biomimetic catalysts with efficient intrinsic peroxidase-like activity. Novel peroxidase activities of CZIS NCs have been

  15. Incubation of Methamphetamine Craving Is Associated with Selective Increases in Expression of Bdnf and Trkb, Glutamate Receptors, and Epigenetic Enzymes in Cue-Activated Fos-Expressing Dorsal Striatal Neurons

    PubMed Central

    Rubio, F. Javier; Zeric, Tamara; Bossert, Jennifer M.; Kambhampati, Sarita; Cates, Hannah M.; Kennedy, Pamela J.; Liu, Qing-Rong; Cimbro, Raffaello; Hope, Bruce T.; Nestler, Eric J.

    2015-01-01

    Cue-induced methamphetamine seeking progressively increases after withdrawal (incubation of methamphetamine craving), but the underlying mechanisms are largely unknown. We determined whether this incubation is associated with alterations in candidate genes in dorsal striatum (DS), a brain area implicated in cue- and context-induced drug relapse. We first measured mRNA expression of 24 candidate genes in whole DS extracts after short (2 d) or prolonged (1 month) withdrawal in rats following extended-access methamphetamine or saline (control condition) self-administration (9 h/d, 10 d). We found minimal changes. Next, using fluorescence-activated cell sorting, we compared gene expression in Fos-positive dorsal striatal neurons, which were activated during “incubated” cue-induced drug-seeking tests after prolonged withdrawal, with nonactivated Fos-negative neurons. We found significant increases in mRNA expression of immediate early genes (Arc, Egr1), Bdnf and its receptor (Trkb), glutamate receptor subunits (Gria1, Gria3, Grm1), and epigenetic enzymes (Hdac3, Hdac4, Hdac5, GLP, Dnmt3a, Kdm1a) in the Fos-positive neurons only. Using RNAscope to determine striatal subregion and cell-type specificity of the activated neurons, we measured colabeling of Fos with Drd1 and Drd2 in three DS subregions. Fos expression was neither subregion nor cell-type specific (52.5 and 39.2% of Fos expression colabeled with Drd1 and Drd2, respectively). Finally, we found that DS injections of SCH23390 (C17H18ClNO), a D1-family receptor antagonist known to block cue-induced Fos induction, decreased incubated cue-induced methamphetamine seeking after prolonged withdrawal. Results demonstrate a critical role of DS in incubation of methamphetamine craving and that this incubation is associated with selective gene-expression alterations in cue-activated D1- and D2-expressing DS neurons. PMID:26019338

  16. Real-time examination of aminoglycoside activity towards bacterial mimetic membranes using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D).

    PubMed

    Joshi, Tanmaya; Voo, Zhi Xiang; Graham, Bim; Spiccia, Leone; Martin, Lisandra L

    2015-02-01

    The rapid increase in multi-drug resistant bacteria has resulted in previously discontinued treatments being revisited. Aminoglycosides are effective "old" antibacterial agents that fall within this category. Despite extensive usage and understanding of their intracellular targets, there is limited mechanistic knowledge regarding how aminoglycosides penetrate bacterial membranes. Thus, the activity of two well-known aminoglycosides, kanamycin A and neomycin B, towards a bacterial mimetic membrane (DMPC:DMPG (4:1)) was examined using a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). The macroscopic effect of increasing the aminoglycoside concentration showed that kanamycin A exerts a threshold response, switching from binding to the membrane to disruption of the surface. Neomycin B, however, disrupted the membrane at all concentrations examined. At concentrations above the threshold value observed for kanamycin A, both aminoglycosides revealed similar mechanistic details. That is, they both inserted into the bacterial mimetic lipid bilayer, prior to disruption via loss of materials, presumably aminoglycoside-membrane composites. Depth profile analysis of this membrane interaction was achieved using the overtones of the quartz crystal sensor. The measured data is consistent with a two-stage process in which insertion of the aminoglycoside precedes the 'detergent-like' removal of membranes from the sensor. The results of this study contribute to the insight required for aminoglycosides to be reconsidered as active antimicrobial agents/co-agents by providing details of activity at the bacterial membrane. Kanamycin and neomycin still offer potential as antimicrobial therapeutics for the future and the QCM-D method illustrates great promise for screening new antibacterial or antiviral drug candidates.

  17. Transient inhibition of TrkB kinase after status epilepticus prevents development of temporal lobe epilepsy.

    PubMed

    Liu, Gumei; Gu, Bin; He, Xiao-Ping; Joshi, Rasesh B; Wackerle, Harold D; Rodriguiz, Ramona Marie; Wetsel, William C; McNamara, James O

    2013-07-10

    Temporal lobe epilepsy is the most common and often devastating form of human epilepsy. The molecular mechanism underlying the development of temporal lobe epilepsy remains largely unknown. Emerging evidence suggests that activation of the BDNF receptor TrkB promotes epileptogenesis caused by status epilepticus. We investigated a mouse model in which a brief episode of status epilepticus results in chronic recurrent seizures, anxiety-like behavior, and destruction of hippocampal neurons. We used a chemical-genetic approach to selectively inhibit activation of TrkB. We demonstrate that inhibition of TrkB commencing after status epilepticus and continued for 2 weeks prevents recurrent seizures, ameliorates anxiety-like behavior, and limits loss of hippocampal neurons when tested weeks to months later. That transient inhibition commencing after status epilepticus can prevent these long-lasting devastating consequences establishes TrkB signaling as an attractive target for developing preventive treatments of epilepsy in humans. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Mice lacking TrkB in parvalbumin-positive cells exhibit sexually dimorphic behavioral phenotypes.

    PubMed

    Lucas, Elizabeth K; Jegarl, Anita; Clem, Roger L

    2014-11-01

    Activity-dependent brain-derived neurotrophic factor (BDNF) signaling through receptor tyrosine kinase B (TrkB) is required for cued fear memory consolidation and extinction. Although BDNF is primarily secreted from glutamatergic neurons, TrkB is expressed by other genetically defined cells whose contributions to the behavioral effects of BDNF remain poorly understood. Parvalbumin (PV)-positive interneurons, which are highly enriched in TrkB, are emerging as key regulators of fear memory expression. We therefore hypothesized that activity-dependent BDNF signaling in PV-interneurons may modulate emotional learning. To test this hypothesis, we utilized the LoxP/Cre system for conditional deletion of TrkB in PV-positive cells to examine the impact of cell-autonomous BDNF signaling on Pavlovian fear conditioning and extinction. However, behavioral abnormalities indicative of vestibular dysfunction precluded the use of homozygous conditional knockouts in tests of higher cognitive functioning. While vestibular dysfunction was apparent in both sexes, female conditional knockouts exhibited an exacerbated phenotype, including extreme motor hyperactivity and circling behavior, compared to their male littermates. Heterozygous conditional knockouts were spared of vestibular dysfunction. While fear memory consolidation was unaffected in heterozygotes of both sexes, males exhibited impaired extinction consolidation compared to their littermate controls. Our findings complement evidence from human and rodent studies suggesting that BDNF signaling promotes consolidation of extinction and point to PV-positive neurons as a discrete population that mediates these effects in a sex-specific manner.

  19. A Novel Apolipoprotein C-II Mimetic Peptide That Activates Lipoprotein Lipase and Decreases Serum Triglycerides in Apolipoprotein E–Knockout Mice

    PubMed Central

    Sakurai, Toshihiro; Sakurai-Ikuta, Akiko; Sviridov, Denis; Freeman, Lita; Ahsan, Lusana; Remaley, Alan T.

    2015-01-01

    Apolipoprotein A-I (apoA-I) mimetic peptides are currently being developed as possible new agents for the treatment of cardiovascular disease based on their ability to promote cholesterol efflux and their other beneficial antiatherogenic properties. Many of these peptides, however, have been reported to cause transient hypertriglyceridemia due to inhibition of lipolysis by lipoprotein lipase (LPL). We describe a novel bihelical amphipathic peptide (C-II-a) that contains an amphipathic helix (18A) for binding to lipoproteins and stimulating cholesterol efflux as well as a motif based on the last helix of apolipoprotein C-II (apoC-II) that activates lipolysis by LPL. The C-II-a peptide promoted cholesterol efflux from ATP-binding cassette transporter ABCA1-transfected BHK cells similar to apoA-I mimetic peptides. Furthermore, it was shown in vitro to be comparable to the full-length apoC-II protein in activating lipolysis by LPL. When added to serum from a patient with apoC-II deficiency, it restored normal levels of LPL-induced lipolysis and also enhanced lipolysis in serum from patients with type IV and V hypertriglyceridemia. Intravenous injection of C-II-a (30 mg/kg) in apolipoprotein E–knockout mice resulted in a significant reduction of plasma cholesterol and triglycerides of 38 ± 6% and 85 ± 7%, respectively, at 4 hours. When coinjected with the 5A peptide (60 mg/kg), the C-II-a (30 mg/kg) peptide was found to completely block the hypertriglyceridemic effect of the 5A peptide in C57Bl/6 mice. In summary, C-II-a is a novel peptide based on apoC-II, which promotes cholesterol efflux and lipolysis and may therefore be useful for the treatment of apoC-II deficiency and other forms of hypertriglyceridemia. PMID:25395590

  20. A novel apolipoprotein C-II mimetic peptide that activates lipoprotein lipase and decreases serum triglycerides in apolipoprotein E-knockout mice.

    PubMed

    Amar, Marcelo J A; Sakurai, Toshihiro; Sakurai-Ikuta, Akiko; Sviridov, Denis; Freeman, Lita; Ahsan, Lusana; Remaley, Alan T

    2015-02-01

    Apolipoprotein A-I (apoA-I) mimetic peptides are currently being developed as possible new agents for the treatment of cardiovascular disease based on their ability to promote cholesterol efflux and their other beneficial antiatherogenic properties. Many of these peptides, however, have been reported to cause transient hypertriglyceridemia due to inhibition of lipolysis by lipoprotein lipase (LPL). We describe a novel bihelical amphipathic peptide (C-II-a) that contains an amphipathic helix (18A) for binding to lipoproteins and stimulating cholesterol efflux as well as a motif based on the last helix of apolipoprotein C-II (apoC-II) that activates lipolysis by LPL. The C-II-a peptide promoted cholesterol efflux from ATP-binding cassette transporter ABCA1-transfected BHK cells similar to apoA-I mimetic peptides. Furthermore, it was shown in vitro to be comparable to the full-length apoC-II protein in activating lipolysis by LPL. When added to serum from a patient with apoC-II deficiency, it restored normal levels of LPL-induced lipolysis and also enhanced lipolysis in serum from patients with type IV and V hypertriglyceridemia. Intravenous injection of C-II-a (30 mg/kg) in apolipoprotein E-knockout mice resulted in a significant reduction of plasma cholesterol and triglycerides of 38 ± 6% and 85 ± 7%, respectively, at 4 hours. When coinjected with the 5A peptide (60 mg/kg), the C-II-a (30 mg/kg) peptide was found to completely block the hypertriglyceridemic effect of the 5A peptide in C57Bl/6 mice. In summary, C-II-a is a novel peptide based on apoC-II, which promotes cholesterol efflux and lipolysis and may therefore be useful for the treatment of apoC-II deficiency and other forms of hypertriglyceridemia. U.S. Government work not protected by U.S. copyright.

  1. TrkB Signaling in Dorsal Raphe Nucleus is Essential for Antidepressant Efficacy and Normal Aggression Behavior.

    PubMed

    Adachi, Megumi; Autry, Anita E; Mahgoub, Melissa; Suzuki, Kanzo; Monteggia, Lisa M

    2017-03-01

    Brain-derived neurotrophic factor (BDNF) and its high affinity receptor, tropomyosin receptor kinase B (TrkB), have important roles in neural plasticity and are required for antidepressant efficacy. Studies examining the role of BDNF-TrkB signaling in depression and antidepressant efficacy have largely focused on the limbic system, leaving it unclear whether this signaling is important in other brain regions. BDNF and TrkB are both highly expressed in the dorsal raphe nucleus (DRN), a brain region that has been suggested to have a role in depression and antidepressant action, although it is unknown whether BDNF and TrkB in the dorsal raphe nucleus are involved in these processes. We combined the adeno-associated virus (AAV) with the Cre-loxP site-specific recombination system to selectively knock down either Bdnf or TrkB in the DRN. These mice were then characterized in several behavioral paradigms including measures of depression-related behavior and antidepressant efficacy. We show that knockdown of TrkB, but not Bdnf, in the DRN results in loss of antidepressant efficacy and increased aggression-related behavior. We also show that knockdown of TrkB or Bdnf in this brain region does not have an impact on weight, activity levels, anxiety, or depression-related behaviors. These data reveal a critical role for TrkB signaling in the DRN in mediating antidepressant responses and normal aggression behavior. The results also suggest a non-cell autonomous role for BDNF in the DRN in mediating antidepressant efficacy.

  2. Helix mimetics: Recent developments.

    PubMed

    Wilson, Andrew J

    2015-10-01

    The development of protein-protein interaction (PPIs) inhibitors represents a challenging goal in chemical biology and drug discovery. PPIs are problematic targets because they involve large surfaces with less well defined features and recognition motifs that are less amenable to conventional experimental and computational ligand discovery methodologies. α-Helix mediated PPIs represent a sub group with a clearly defined interface and thus may be more amenable to the development of generic ligand discovery methods. Indeed, this is borne out in numerous studies using peptides covalently constrained into a helical conformation resulting in improvement of myriad biophysical and cellular properties. It is however desirable to have small molecule alternatives: a helix mimetic (proteomimetic) is a generic small molecule scaffold that projects functional groups in a similar spatial orientation so as to mimic the presentation of key amino acid side chains from the helix that mediates the PPI. The first true example of a helix mimetic was described over a decade ago however this approach has not yet been elaborated to the extent that it receives similar levels of attention to constrained peptides. This review explores recent significant developments in the area of small molecule α-helix mimetics and provides a critical overview of success stories, potential limitations of the approach, and areas for future development. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Incubation of methamphetamine craving is associated with selective increases in expression of Bdnf and trkb, glutamate receptors, and epigenetic enzymes in cue-activated fos-expressing dorsal striatal neurons.

    PubMed

    Li, Xuan; Rubio, F Javier; Zeric, Tamara; Bossert, Jennifer M; Kambhampati, Sarita; Cates, Hannah M; Kennedy, Pamela J; Liu, Qing-Rong; Cimbro, Raffaello; Hope, Bruce T; Nestler, Eric J; Shaham, Yavin

    2015-05-27

    Cue-induced methamphetamine seeking progressively increases after withdrawal (incubation of methamphetamine craving), but the underlying mechanisms are largely unknown. We determined whether this incubation is associated with alterations in candidate genes in dorsal striatum (DS), a brain area implicated in cue- and context-induced drug relapse. We first measured mRNA expression of 24 candidate genes in whole DS extracts after short (2 d) or prolonged (1 month) withdrawal in rats following extended-access methamphetamine or saline (control condition) self-administration (9 h/d, 10 d). We found minimal changes. Next, using fluorescence-activated cell sorting, we compared gene expression in Fos-positive dorsal striatal neurons, which were activated during "incubated" cue-induced drug-seeking tests after prolonged withdrawal, with nonactivated Fos-negative neurons. We found significant increases in mRNA expression of immediate early genes (Arc, Egr1), Bdnf and its receptor (Trkb), glutamate receptor subunits (Gria1, Gria3, Grm1), and epigenetic enzymes (Hdac3, Hdac4, Hdac5, GLP, Dnmt3a, Kdm1a) in the Fos-positive neurons only. Using RNAscope to determine striatal subregion and cell-type specificity of the activated neurons, we measured colabeling of Fos with Drd1 and Drd2 in three DS subregions. Fos expression was neither subregion nor cell-type specific (52.5 and 39.2% of Fos expression colabeled with Drd1 and Drd2, respectively). Finally, we found that DS injections of SCH23390 (C17H18ClNO), a D1-family receptor antagonist known to block cue-induced Fos induction, decreased incubated cue-induced methamphetamine seeking after prolonged withdrawal. Results demonstrate a critical role of DS in incubation of methamphetamine craving and that this incubation is associated with selective gene-expression alterations in cue-activated D1- and D2-expressing DS neurons. Copyright © 2015 the authors 0270-6474/15/358232-13$15.00/0.

  4. Collagen-gelatin mixtures as wound model, and substrates for VEGF-mimetic peptide binding and endothelial cell activation.

    PubMed

    Chan, Tania R; Stahl, Patrick J; Li, Yang; Yu, S Michael

    2015-03-01

    In humans, high level of collagen remodeling is seen during normal physiological events such as bone renewal, as well as in pathological conditions, such as arthritis, tumor growth and other chronic wounds. Our lab recently discovered that collagen mimetic peptide (CMP) is able to hybridize with denatured collagens at these collagen remodeling sites with high affinity. Here, we show that the CMP's high binding affinity to denatured collagens can be utilized to deliver angiogenic signals to scaffolds composed of heat-denatured collagens (gelatins). We first demonstrate hybridization between denatured collagens and QKCMP, a CMP with pro-angiogenic QK domain. We show that high levels of QKCMP can be immobilized to a new artificial matrix containing both fibrous type I collagen and heat denatured collagen through triple helix hybridization, and that the QKCMP is able to stimulate early angiogenic response of endothelial cells (ECs). We also show that the QKCMP can bind to excised tissues from burn injuries in cutaneous mouse model, suggesting its potential for promoting neovascularization of burn wounds. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  5. Collagen-Gelatin Mixtures as Wound Model, and Substrates for VEGF-Mimetic Peptide Binding and Endothelial Cell Activation

    PubMed Central

    Chan, Tania R.; Stahl, Patrick J.; Li, Yang; Yu, S. Michael

    2015-01-01

    In humans, high level of collagen remodeling is seen during normal physiological events such as bone renewal, as well as in pathological conditions, such as arthritis, tumor growth and other chronic wounds. Our lab recently discovered that collagen mimetic peptide (CMP) is able to hybridize with denatured collagens at these collagen remodeling sites with high affinity. Here, we show that the CMP's high binding affinity to denatured collagens can be utilized to deliver angiogenic signals to scaffolds composed of heat-denatured collagens (gelatins). We first demonstrate hybridization between denatured collagens and QKCMP, a CMP with pro-angiogenic QK domain. We show that high levels of QKCMP can be immobilized to a new artificial matrix containing both fibrous type I collagen and heat denatured collagen through triple helix hybridization, and that the QKCMP is able to stimulate early angiogenic response of endothelial cells (ECs). We also show that the QKCMP can bind to excised tissues from burn injuries in cutaneous mouse model, suggesting its potential for promoting neovascularization of burn wounds. PMID:25584990

  6. TrkB kinase is required for recovery, but not loss, of cortical responses following monocular deprivation

    PubMed Central

    Kaneko, Megumi; Hanover, Jessica L; England, Pamela M; Stryker, Michael P

    2008-01-01

    Changes in visual cortical responses that are induced by monocular visual deprivation are a widely studied example of competitive, experience-dependent neural plasticity. It has been thought that the deprived-eye pathway will fail to compete against the open-eye pathway for limited amounts of brain-derived neurotrophic factor, which acts on TrkB and is needed to sustain effective synaptic connections. We tested this model by using a chemical-genetic approach in mice to inhibit TrkB kinase activity rapidly and specifically during the induction of cortical plasticity in vivo. Contrary to the model, TrkB kinase activity was not required for any of the effects of monocular deprivation. When the deprived eye was re-opened during the critical period, cortical responses to it recovered. This recovery was blocked by TrkB inhibition. These findings suggest a more conventional trophic role for TrkB signaling in the enhancement of responses or growth of new connections, rather than a role in competition. PMID:18311133

  7. TrkB kinase is required for recovery, but not loss, of cortical responses following monocular deprivation.

    PubMed

    Kaneko, Megumi; Hanover, Jessica L; England, Pamela M; Stryker, Michael P

    2008-04-01

    Changes in visual cortical responses that are induced by monocular visual deprivation are a widely studied example of competitive, experience-dependent neural plasticity. It has been thought that the deprived-eye pathway will fail to compete against the open-eye pathway for limited amounts of brain-derived neurotrophic factor, which acts on TrkB and is needed to sustain effective synaptic connections. We tested this model by using a chemical-genetic approach in mice to inhibit TrkB kinase activity rapidly and specifically during the induction of cortical plasticity in vivo. Contrary to the model, TrkB kinase activity was not required for any of the effects of monocular deprivation. When the deprived eye was re-opened during the critical period, cortical responses to it recovered. This recovery was blocked by TrkB inhibition. These findings suggest a more conventional trophic role for TrkB signaling in the enhancement of responses or growth of new connections, rather than a role in competition.

  8. B cell lymphoma-2 (BCL-2) homology domain 3 (BH3) mimetics demonstrate differential activities dependent upon the functional repertoire of pro- and anti-apoptotic BCL-2 family proteins.

    PubMed

    Renault, Thibaud T; Elkholi, Rana; Bharti, Archana; Chipuk, Jerry E

    2014-09-19

    The B cell lymphoma-2 (BCL-2) family is the key mediator of cellular sensitivity to apoptosis during pharmacological interventions for numerous human pathologies, including cancer. There is tremendous interest to understand how the proapoptotic BCL-2 effector members (e.g. BCL-2-associated X protein, BAX) cooperate with the BCL-2 homology domain only (BH3-only) subclass (e.g. BCL-2 interacting mediator of death, BIM; BCL-2 interacting-domain death agonist, BID) to induce mitochondrial outer membrane permeabilization (MOMP) and apoptosis and whether these mechanisms may be pharmacologically exploited to enhance the killing of cancer cells. Indeed, small molecule inhibitors of the anti-apoptotic BCL-2 family members have been designed rationally. However, the success of these "BH3 mimetics" in the clinic has been limited, likely due to an incomplete understanding of how these drugs function in the presence of multiple BCL-2 family members. To increase our mechanistic understanding of how BH3 mimetics cooperate with multiple BCL-2 family members in vitro, we directly compared the activity of several BH3-mimetic compounds (i.e. ABT-263, ABT-737, GX15-070, HA14.1, TW-37) in biochemically defined large unilamellar vesicle model systems that faithfully recapitulate BAX-dependent mitochondrial outer membrane permeabilization. Our investigations revealed that the presence of BAX, BID, and BIM differentially regulated the ability of BH3 mimetics to derepress proapoptotic molecules from anti-apoptotic proteins. Using mitochondria loaded with fluorescent BH3 peptides and cells treated with inducers of cell death, these differences were supported. Together, these data suggest that although the presence of anti-apoptotic BCL-2 proteins primarily dictates cellular sensitivity to BH3 mimetics, additional specificity is conferred by proapoptotic BCL-2 proteins. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Wood mimetic hydrogel beads for enzyme immobilization.

    PubMed

    Park, Saerom; Kim, Sung Hee; Won, Keehoon; Choi, Joon Weon; Kim, Yong Hwan; Kim, Hyung Joo; Yang, Yung-Hun; Lee, Sang Hyun

    2015-01-22

    Wood component-based composite hydrogels have potential applications in biomedical fields owing to their low cost, biodegradability, and biocompatibility. The controllable properties of wood mimetic composites containing three major wood components are useful for enzyme immobilization. Here, lipase from Candida rugosa was entrapped in wood mimetic beads containing cellulose, xylan, and lignin by dissolving wood components with lipase in [Emim][Ac], followed by reconstitution. Lipase entrapped in cellulose/xylan/lignin beads in a 5:3:2 ratio showed the highest activity; this ratio is very similar to that in natural wood. The lipase entrapped in various wood mimetic beads showed increased thermal and pH stability. The half-life times of lipase entrapped in cellulose/alkali lignin hydrogel were 31- and 82-times higher than those of free lipase during incubation under denaturing conditions of high temperature and low pH, respectively. Owing to their biocompatibility, biodegradability, and controllable properties, wood mimetic hydrogel beads can be used to immobilize various enzymes for applications in the biomedical, bioelectronic, and biocatalytic fields.

  10. Apolipoprotein A-I mimetic peptides inhibit expression and activity of hypoxia-inducible factor-1α in human ovarian cancer cell lines and a mouse ovarian cancer model.

    PubMed

    Gao, Feng; Chattopadhyay, Arnab; Navab, Mohamad; Grijalva, Victor; Su, Feng; Fogelman, Alan M; Reddy, Srinivasa T; Farias-Eisner, Robin

    2012-08-01

    Our previous results demonstrated that the apolipoprotein A-I (apoA-I) mimetic peptides L-4F and L-5F inhibit vascular endothelial growth factor production and tumor angiogenesis. The present study was designed to test whether apoA-I mimetic peptides inhibit the expression and activity of hypoxia-inducible factor-1α (HIF-1α), which plays a critical role in the production of angiogenic factors and angiogenesis. Immunohistochemistry staining was used to examine the expression of HIF-1α in tumor tissues. Immunoblotting, real-time polymerase chain reaction, immunofluorescence, and luciferase activity assays were used to determine the expression and activity of HIF-1α in human ovarian cancer cell lines. Immunohistochemistry staining demonstrated that L-4F treatment dramatically decreased HIF-1α expression in mouse ovarian tumor tissues. L-4F inhibited the expression and activity of HIF-1α induced by low oxygen concentration, cobalt chloride (CoCl(2), a hypoxia-mimic compound), lysophosphatidic acid, and insulin in two human ovarian cancer cell lines, OV2008 and CAOV-3. L-4F had no effect on the insulin-induced phosphorylation of Akt, but inhibited the activation of extracellular signal-regulated kinase and p70s6 kinase, leading to the inhibition of HIF-1α synthesis. Pretreatment with L-4F dramatically accelerated the proteasome-dependent protein degradation of HIF-1α in both insulin- and CoCl(2)-treated cells. The inhibitory effect of L-4F on HIF-1α expression is in part mediated by the reactive oxygen species-scavenging effect of L-4F. ApoA-I mimetic peptides inhibit the expression and activity of HIF-1α in both in vivo and in vitro models, suggesting the inhibition of HIF-1α may be a critical mechanism responsible for the suppression of tumor progression by apoA-I mimetic peptides.

  11. Effect of glatiramer acetate on peripheral blood brain-derived neurotrophic factor and phosphorylated TrkB levels in relapsing-remitting multiple sclerosis.

    PubMed

    Vacaras, Vitalie; Major, Zsigmond Z; Muresanu, Dafin F; Krausz, Tibor L; Marginean, Ioan; Buzoianu, Dana A

    2014-01-01

    Glatiramer acetate (GA) is one of the most widely used disease-modifying drugs for the treatment of relapsing-remitting multiple sclerosis; is assumed to have inductor effects on neurotrophic factor expression. One of these neurotrophic factor systems is the brain-derived neurotrophic factor (BDNF)/receptor tyrosine kinase B (TrkB) pathway. Peripheral blood is thought to contain soluble BDNF, and some blood cells express TrkB. We attempted to determine whether GA treatment leads to changes in plasma BDNF levels and TrkB activation. Such a phenomenon are relapsing-remitting multiple sclerosis patients is significantly reduced; GA treatment is not influencing peripheral BDNF levels, after one year of sustained therapy, not from the point of view of total free BDNF nor the phosphorylated TrkB.

  12. Targeted Delivery of TrkB Receptor to Phrenic Motoneurons Enhances Functional Recovery of Rhythmic Phrenic Activity after Cervical Spinal Hemisection

    PubMed Central

    Gransee, Heather M.; Zhan, Wen-Zhi; Sieck, Gary C.; Mantilla, Carlos B.

    2013-01-01

    Progressive recovery of rhythmic phrenic activity occurs over time after a spinal cord hemisection involving unilateral transection of anterolateral funiculi at C2 (SH). Brain-derived neurotrophic factor (BDNF) acting through its full-length tropomyosin related kinase receptor subtype B (TrkB.FL) contributes to neuroplasticity after spinal cord injury, but the specific cellular substrates remain unclear. We hypothesized that selectively targeting increased TrkB.FL expression to phrenic motoneurons would be sufficient to enhance recovery of rhythmic phrenic activity after SH. Several adeno-associated virus (AAV) serotypes expressing GFP were screened to determine specificity for phrenic motoneuron transduction via intrapleural injection in adult rats. GFP expression was present in the cervical spinal cord 3 weeks after treatment with AAV serotypes 7, 8, and 9, but not with AAV2, 6, or rhesus-10. Overall, AAV7 produced the most consistent GFP expression in phrenic motoneurons. SH was performed 3 weeks after intrapleural injection of AAV7 expressing human TrkB.FL-FLAG or saline. Delivery of TrkB.FL-FLAG to phrenic motoneurons was confirmed by FLAG protein expression in the phrenic motor nucleus and human TrkB.FL mRNA expression in microdissected phrenic motoneurons. In all SH rats, absence of ipsilateral diaphragm EMG activity was confirmed at 3 days post-SH, verifying complete interruption of ipsilateral descending drive to phrenic motoneurons. At 14 days post-SH, all AAV7-TrkB.FL treated rats (n = 11) displayed recovery of ipsilateral diaphragm EMG activity compared to 3 out of 8 untreated SH rats (p<0.01). During eupnea, AAV7-TrkB.FL treated rats exhibited 73±7% of pre-SH root mean squared EMG vs. only 31±11% in untreated SH rats displaying recovery (p<0.01). This study provides direct evidence that increased TrkB.FL expression in phrenic motoneurons is sufficient to enhance recovery of ipsilateral rhythmic phrenic activity after SH, indicating that

  13. Targeted delivery of TrkB receptor to phrenic motoneurons enhances functional recovery of rhythmic phrenic activity after cervical spinal hemisection.

    PubMed

    Gransee, Heather M; Zhan, Wen-Zhi; Sieck, Gary C; Mantilla, Carlos B

    2013-01-01

    Progressive recovery of rhythmic phrenic activity occurs over time after a spinal cord hemisection involving unilateral transection of anterolateral funiculi at C2 (SH). Brain-derived neurotrophic factor (BDNF) acting through its full-length tropomyosin related kinase receptor subtype B (TrkB.FL) contributes to neuroplasticity after spinal cord injury, but the specific cellular substrates remain unclear. We hypothesized that selectively targeting increased TrkB.FL expression to phrenic motoneurons would be sufficient to enhance recovery of rhythmic phrenic activity after SH. Several adeno-associated virus (AAV) serotypes expressing GFP were screened to determine specificity for phrenic motoneuron transduction via intrapleural injection in adult rats. GFP expression was present in the cervical spinal cord 3 weeks after treatment with AAV serotypes 7, 8, and 9, but not with AAV2, 6, or rhesus-10. Overall, AAV7 produced the most consistent GFP expression in phrenic motoneurons. SH was performed 3 weeks after intrapleural injection of AAV7 expressing human TrkB.FL-FLAG or saline. Delivery of TrkB.FL-FLAG to phrenic motoneurons was confirmed by FLAG protein expression in the phrenic motor nucleus and human TrkB.FL mRNA expression in microdissected phrenic motoneurons. In all SH rats, absence of ipsilateral diaphragm EMG activity was confirmed at 3 days post-SH, verifying complete interruption of ipsilateral descending drive to phrenic motoneurons. At 14 days post-SH, all AAV7-TrkB.FL treated rats (n = 11) displayed recovery of ipsilateral diaphragm EMG activity compared to 3 out of 8 untreated SH rats (p<0.01). During eupnea, AAV7-TrkB.FL treated rats exhibited 73±7% of pre-SH root mean squared EMG vs. only 31±11% in untreated SH rats displaying recovery (p<0.01). This study provides direct evidence that increased TrkB.FL expression in phrenic motoneurons is sufficient to enhance recovery of ipsilateral rhythmic phrenic activity after SH, indicating that

  14. Promises and Challenges of Smac Mimetics as Cancer Therapeutics.

    PubMed

    Fulda, Simone

    2015-11-15

    Inhibitor of Apoptosis (IAP) proteins block programmed cell death and are expressed at high levels in various human cancers, thus making them attractive targets for cancer drug development. Second mitochondrial activator of caspases (Smac) mimetics are small-molecule inhibitors that mimic Smac, an endogenous antagonist of IAP proteins. Preclinical studies have shown that Smac mimetics can directly trigger cancer cell death or, even more importantly, sensitize tumor cells for various cytotoxic therapies, including conventional chemotherapy, radiotherapy, or novel agents. Currently, several Smac mimetics are under evaluation in early clinical trials as monotherapy or in rational combinations (i.e., GDC-0917/CUDC-427, LCL161, AT-406/Debio1143, HGS1029, and TL32711/birinapant). This review discusses the promise as well as some challenges at the translational interface of exploiting Smac mimetics as cancer therapeutics.

  15. Differential regulation of catalytic and non-catalytic trkB messenger RNAs in the rat hippocampus following seizures induced by systemic administration of kainate.

    PubMed

    Dugich-Djordjevic, M M; Ohsawa, F; Okazaki, T; Mori, N; Day, J R; Beck, K D; Hefti, F

    1995-06-01

    Ribonuclease protection analysis and quantitative in situ hybridization histochemistry were used to investigate the coordination and regional expression of catalytic and non-catalytic trkB messenger RNAs in the adult rat hippocampus following systemic kainate-induced seizures. Changes in trkB expression were compared with the messenger RNA expression of its neurotrophic ligands, brain-derived neurotrophic factor and neurotrophin-3. TrkB messenger RNA expression was increased in the dentate granule cells at 1-4 h following the onset of seizures, and returned to control levels 16-24 h thereafter. In addition, seizures also induced expression of trkB messenger RNA in putative non-neuronal cells at four to seven days in the molecular layer of the dentate gyrus and the stratum lacunosum moleculare of the CA1 region. Hybridization with probes specific for the non-catalytic trkB receptor and the catalytic trkB receptor revealed that the increases at four and seven days in the molecular layers of the hippocampus reflected an up-regulation of only the non-catalytic form of the receptor. Furthermore, the neuronal increases observed 1-4 h were due to an up-regulation of both trkB TK- and trkB TK+ messenger RNAs. It was established that systemic administration of kainate increased brain-derived neurotrophic factor messenger RNA levels in the pyramidal and granule cell regions of the hippocampus 1-4 h following the onset of behaviorally manifested seizure activity. Early changes in neuronal expression of trkB TK- and trkB TK+ messenger RNA paralleled changes in brain-derived neurotrophic factor messenger RNA in the dentate granule cell and CA1 pyramidal cell layers, but not in the CA3 subregion. These data suggest that concomitant regulation of brain-derived neurotrophic factor and its cognate receptor may play a role in the selective vulnerability of hippocampal subregions to kainate-induced neuropathology. Furthermore, these data suggest a dual function for trkB receptor

  16. Apoptosis repressor with caspase recruitment domain modulates second mitochondrial-derived activator of caspases mimetic-induced cell death through BIRC2/MAP3K14 signalling in acute myeloid leukaemia.

    PubMed

    Mak, Po Y; Mak, Duncan H; Ruvolo, Vivian; Jacamo, Rodrigo; Kornblau, Steven M; Kantarjian, Hagop; Andreeff, Michael; Carter, Bing Z

    2014-11-01

    Overexpression of the apoptosis repressor with caspase recruitment domain (ARC, also termed NOL3) protein predicts adverse outcome in patients with acute myeloid leukaemia (AML) and confers drug resistance to AML cells. The second mitochondrial-derived activator of caspases (SMAC, also termed DIABLO) mimetic, birinapant, promotes extrinsic apoptosis in AML cells. SMAC mimetics induce cleavage of cellular inhibitor of apoptosis (cIAP) proteins, leading to stabilization of the nuclear factor-κB (NF-κB)-inducing kinase (MAP3K14, also termed NIK) and activation of non-canonical NF-κB signalling. To enhance the therapeutic potential of SMAC mimetics in AML, we investigated the regulation and role of ARC in birinapant-induced apoptosis. We showed that birinapant increases ARC in AML and bone marrow-derived mesenchymal stromal cells (MSCs). Downregulation of MAP3K14 by siRNA decreased ARC levels and suppressed birinapant-induced ARC increase. Reverse-phase protein array analysis of 511 samples from newly diagnosed AML patients showed that BIRC2 (also termed cIAP1) and ARC were inversely correlated. Knockdown of ARC sensitized, while overexpression attenuated, birinapant-induced apoptosis. Furthermore, ARC knockdown in MSCs sensitized co-cultured AML cells to birinapant-induced apoptosis. Our data demonstrate that ARC is regulated via BIRC2/MAP3K14 signalling and its overexpression in AML or MSCs can function as a resistant factor to birinapant-induced leukaemia cell death, suggesting that strategies to inhibit ARC will improve the therapeutic potential of SMAC mimetics. © 2014 John Wiley & Sons Ltd.

  17. Energy Restriction-mimetic Agents Induce Apoptosis in Prostate Cancer Cells in Part through Epigenetic Activation of KLF6 Tumor Suppressor Gene Expression*

    PubMed Central

    Chen, Chun-Han; Huang, Po-Hsien; Chu, Po-Chen; Chen, Mei-Chuan; Chou, Chih-Chien; Wang, Dasheng; Kulp, Samuel K.; Teng, Che-Ming; Wang, Qianben; Chen, Ching-Shih

    2011-01-01

    Although energy restriction has been recognized as an important target for cancer prevention, the mechanism by which energy restriction-mimetic agents (ERMAs) mediate apoptosis remains unclear. By using a novel thiazolidinedione-derived ERMA, CG-12 (Wei, S., Kulp, S. K., and Chen, C. S. (2010) J. Biol. Chem. 285, 9780–9791), vis-à-vis 2-deoxyglucose and glucose deprivation, we obtain evidence that epigenetic activation of the tumor suppressor gene Kruppel-like factor 6 (KLF6) plays a role in ERMA-induced apoptosis in LNCaP prostate cancer cells. KLF6 regulates the expression of many proapoptotic genes, and shRNA-mediated KLF6 knockdown abrogated the ability of ERMAs to induce apoptosis. Chromatin immunoprecipitation analysis indicates that this KLF6 transcriptional activation was associated with increased histone H3 acetylation and histone H3 lysine 4 trimethylation occupancy at the promoter region. Several lines of evidence demonstrate that the enhancing effect of ERMAs on these active histone marks was mediated through transcriptional repression of histone deacetylases and H3 lysine 4 demethylases by down-regulating Sp1 expression. First, putative Sp1-binding elements are present in the promoters of the affected histone-modifying enzymes, and luciferase reporter assays indicate that site-directed mutagenesis of these Sp1 binding sites significantly diminished the promoter activities. Second, shRNA-mediated knockdown of Sp1 mimicked the repressive effect of energy restriction on these histone-modifying enzymes. Third, ectopic Sp1 expression protected cells from the repressive effect of CG-12 on these histone-modifying enzymes, thereby abolishing the activation of KLF6 expression. Together, these findings underscore the intricate relationship between energy restriction and epigenetic regulation of tumor suppressor gene expression, which has therapeutic relevance to foster novel strategies for prostate cancer therapy. PMID:21282102

  18. Energy restriction-mimetic agents induce apoptosis in prostate cancer cells in part through epigenetic activation of KLF6 tumor suppressor gene expression.

    PubMed

    Chen, Chun-Han; Huang, Po-Hsien; Chu, Po-Chen; Chen, Mei-Chuan; Chou, Chih-Chien; Wang, Dasheng; Kulp, Samuel K; Teng, Che-Ming; Wang, Qianben; Chen, Ching-Shih

    2011-03-25

    Although energy restriction has been recognized as an important target for cancer prevention, the mechanism by which energy restriction-mimetic agents (ERMAs) mediate apoptosis remains unclear. By using a novel thiazolidinedione-derived ERMA, CG-12 (Wei, S., Kulp, S. K., and Chen, C. S. (2010) J. Biol. Chem. 285, 9780-9791), vis-à-vis 2-deoxyglucose and glucose deprivation, we obtain evidence that epigenetic activation of the tumor suppressor gene Kruppel-like factor 6 (KLF6) plays a role in ERMA-induced apoptosis in LNCaP prostate cancer cells. KLF6 regulates the expression of many proapoptotic genes, and shRNA-mediated KLF6 knockdown abrogated the ability of ERMAs to induce apoptosis. Chromatin immunoprecipitation analysis indicates that this KLF6 transcriptional activation was associated with increased histone H3 acetylation and histone H3 lysine 4 trimethylation occupancy at the promoter region. Several lines of evidence demonstrate that the enhancing effect of ERMAs on these active histone marks was mediated through transcriptional repression of histone deacetylases and H3 lysine 4 demethylases by down-regulating Sp1 expression. First, putative Sp1-binding elements are present in the promoters of the affected histone-modifying enzymes, and luciferase reporter assays indicate that site-directed mutagenesis of these Sp1 binding sites significantly diminished the promoter activities. Second, shRNA-mediated knockdown of Sp1 mimicked the repressive effect of energy restriction on these histone-modifying enzymes. Third, ectopic Sp1 expression protected cells from the repressive effect of CG-12 on these histone-modifying enzymes, thereby abolishing the activation of KLF6 expression. Together, these findings underscore the intricate relationship between energy restriction and epigenetic regulation of tumor suppressor gene expression, which has therapeutic relevance to foster novel strategies for prostate cancer therapy.

  19. TrkB blockade in the hippocampus after training or retrieval impairs memory: protection from consolidation impairment by histone deacetylase inhibition.

    PubMed

    Blank, Martina; Petry, Fernanda S; Lichtenfels, Martina; Valiati, Fernanda E; Dornelles, Arethuza S; Roesler, Rafael

    2016-03-01

    Relatively little is known about the requirement of signaling initiated by brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin receptor kinase B (TrkB), in the early phases of memory consolidation, as well as about its possible functional interactions with epigenetic mechanisms. Here we show that blocking TrkB in the dorsal hippocampus after learning or retrieval impairs retention of memory for inhibitory avoidance (IA). More importantly, the impairing effect of TrkB antagonism on consolidation was completely prevented by the histone deacetylase (HDAC) inhibitor sodium butyrate (NaB). Male Wistar rats were given an intrahippocampal infusion of saline (SAL) or NaB before training, followed by an infusion of either vehicle (VEH) or the selective TrkB antagonist ANA-12 immediately after training. In a second experiment, the infusions were administered before and after retrieval. ANA-12 after either training or retrieval produced a significant impairment in a subsequent memory retention test. Pretraining administration of NaB prevented the effect of ANA-12, although NaB given before retrieval did not alter the impairment resulting from TrkB blockade. The results indicate that inhibition of BDNF/TrkB in the hippocampus can hinder consolidation and reconsolidation of IA memory. However, TrkB activity is not required for consolidation in the presence of NaB, suggesting that a dysfunction in BDNF/TrkB signaling can be fully compensated by HDAC inhibition to allow hippocampal memory formation.

  20. Instabilities in mimetic matter perturbations

    NASA Astrophysics Data System (ADS)

    Firouzjahi, Hassan; Gorji, Mohammad Ali; Mansoori, Seyed Ali Hosseini

    2017-07-01

    We study cosmological perturbations in mimetic matter scenario with a general higher derivative function. We calculate the quadratic action and show that both the kinetic term and the gradient term have the wrong sings. We perform the analysis in both comoving and Newtonian gauges and confirm that the Hamiltonians and the associated instabilities are consistent with each other in both gauges. The existence of instabilities is independent of the specific form of higher derivative function which generates gradients for mimetic field perturbations. It is verified that the ghost instability in mimetic perturbations is not associated with the higher derivative instabilities such as the Ostrogradsky ghost.

  1. LINGO-1 negatively regulates TrkB phosphorylation after ocular hypertension.

    PubMed

    Fu, Qing-Ling; Hu, Bing; Li, Xin; Shao, Zhaohui; Shi, Jian-Bo; Wu, Wutian; So, Kwok-Fai; Mi, Sha

    2010-03-01

    The antagonism of LINGO-1, a CNS-specific negative regulator of neuronal survival, was shown to promote short-term survival of retinal ganglion cell (RGC) in an ocular hypertension model. LINGO-1 antagonists, combined with brain-derived neurotrophic factor (BDNF), can increase the length of neuron survival through an unclear molecular mechanism. To determine the relationship between LINGO-1 and BDNF/TrkB receptor in neuronal protection, we show here that LINGO-1 forms a receptor complex with TrkB and negatively regulates its activation in the retina after ocular hypertension injury. LINGO-1 antagonist antibody 1A7 or soluble LINGO-1 (LINGO-1-Fc) treatment upregulates phospho-TrkB phosphorylation and leads to RGC survival after high intraocular pressure injury. This neuronal protective effect was blocked by anti-BDNF antibody. LINGO-1 antagonism therefore promotes RGC survival by regulating the BDNF and TrkB signaling pathway after ocular hypertension.

  2. Impaired TrkB receptor signaling underlies corticostriatal dysfunction in Huntington's disease.

    PubMed

    Plotkin, Joshua L; Day, Michelle; Peterson, Jayms D; Xie, Zhong; Kress, Geraldine J; Rafalovich, Igor; Kondapalli, Jyothisri; Gertler, Tracy S; Flajolet, Marc; Greengard, Paul; Stavarache, Mihaela; Kaplitt, Michael G; Rosinski, Jim; Chan, C Savio; Surmeier, D James

    2014-07-02

    Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder. The debilitating choreic movements that plague HD patients have been attributed to striatal degeneration induced by the loss of cortically supplied brain-derived neurotrophic factor (BDNF). Here, we show that in mouse models of early symptomatic HD, BDNF delivery to the striatum and its activation of tyrosine-related kinase B (TrkB) receptors were normal. However, in striatal neurons responsible for movement suppression, TrkB receptors failed to properly engage postsynaptic signaling mechanisms controlling the induction of potentiation at corticostriatal synapses. Plasticity was rescued by inhibiting p75 neurotrophin receptor (p75NTR) signaling or its downstream target phosphatase-and-tensin-homolog-deleted-on-chromosome-10 (PTEN). Thus, corticostriatal synaptic dysfunction early in HD is attributable to a correctable defect in the response to BDNF, not its delivery. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Blocking GSK3β-mediated dynamin1 phosphorylation enhances BDNF-dependent TrkB endocytosis and the protective effects of BDNF in neuronal and mouse models of Alzheimer's disease.

    PubMed

    Liu, Xiang-Hua; Geng, Zhao; Yan, Jing; Li, Ting; Chen, Qun; Zhang, Qun-Ye; Chen, Zhe-Yu

    2015-02-01

    Endocytosis of tropomyosin related kinase B (TrkB) receptors has critical roles in brain-derived neurotrophic factor (BDNF) mediated signal transduction and biological function, however the mechanism that is governing TrkB endocytosis is still not completely understood. In this study, we showed that GSK3β, a key kinase in neuronal development and survival, could regulate TrkB endocytosis through phosphorylating dynamin1 (Dyn1) but not dynamin2 (Dyn2). Moreover, we found that beta-amyloid (Aβ) oligomer exposure could impair BDNF-dependent TrkB endocytosis and Akt activation through enhancing GSK3β activity in cultured hippocampal neurons, which suggested that BDNF-induced TrkB endocytosis and the subsequent signaling were impaired in neuronal model of Alzheimer's disease (AD). Notably, we found that inhibiting GSK3β phosphorylating Dyn1 by using TAT-Dyn1SpS could rescue the impaired TrkB endocytosis and Akt activation upon BDNF stimuli under Aβ exposure. Finally, TAT-Dyn1SpS could facilitate BDNF-mediated neuronal survival and cognitive enhancement in mouse models of AD. These results clarified a role of GSK3β in BDNF-dependent TrkB endocytosis and the subsequent signaling, and provided a potential new strategy by inhibiting GSK3β-induced Dyn1 phosphorylation for AD treatment.

  4. Pharmacological characterization of six trkB antibodies reveals a novel class of functional agents for the study of the BDNF receptor

    PubMed Central

    Cazorla, M; Arrang, JM; Prémont, J

    2011-01-01

    BACKGROUND AND PURPOSE By interacting with trkB receptors, brain-derived neurotrophic factor (BDNF) triggers various signalling pathways responsible for neurone survival, differentiation and modulation of synaptic transmission. Numerous reports have implicated BDNF and trkB in the pathogenesis of various central nervous system affections and in cancer, thus representing trkB as a promising therapeutic target. In this study, we used an antibody-based approach to search for trkB-selective functional reagents. EXPERIMENTAL APPROACH Six commercially available polyclonal and monoclonal antibodies were tested on recombinant and native, human and rodent trkB receptors. Functional and pharmacological characterization was performed using a modified version of the KIRA-elisa method and radioligand binding studies. Western blot analyses and neurite outgrowth assays were carried out to determine the specificity and selectivity of antibody effects. The survival properties of one antibody were further assessed on cultured neurones in a serum-deprived paradigm. KEY RESULTS The functional trkB-selective antibodies showed distinct pharmacological profiles, ranging from partial agonists to antagonists, acting on trkB receptors through allosteric modulations. The same diversity of effects was observed on the mitogen-activated protein kinase signalling pathway downstream of trkB and on the subsequent neurite outgrowth. One antibody with partial agonist activity demonstrated cell survival properties by activating the Akt pathway. Finally, these antibodies were functionally validated as true trkB-selective ligands because they failed activating trkA or trkC, and contrary to BDNF, none of them bind to p75NTR. CONCLUSIONS AND IMPLICATIONS These trkB-selective antibodies represent a novel class of pharmacological tools to explore the pathophysiological roles of trkB and its potential therapeutic relevance for the treatment of various disorders. PMID:21039416

  5. Retrolinkin recruits the WAVE1 protein complex to facilitate BDNF-induced TrkB endocytosis and dendrite outgrowth

    PubMed Central

    Xu, Chenchang; Fu, Xiuping; Zhu, Shaoxia; Liu, Jia-Jia

    2016-01-01

    Retrolinkin, a neuronal membrane protein, coordinates with endophilin A1 and mediates early endocytic trafficking and signal transduction of the ligand–receptor complex formed between brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase B (TrkB), in dendrites of CNS neurons. Here we report that retrolinkin interacts with the CYFIP1/2 subunit of the WAVE1 complex, a member of the WASP/WAVE family of nucleation-promoting factors that binds and activates the Arp2/3 complex to promote branched actin polymerization. WAVE1, not N-WASP, is required for BDNF-induced TrkB endocytosis and dendrite outgrowth. Disruption of the interaction between retrolinkin and CYFIP1/2 impairs recruitment of WAVE1 to neuronal plasma membrane upon BDNF addition and blocks internalization of activated TrkB. We also show that WAVE1-mediated endocytosis of BDNF-activated TrkB is actin dependent and clathrin independent. These results not only reveal the mechanistic role of retrolinkin in BDNF–TrkB endocytosis, but also indicate that WASP/WAVE-dependent actin polymerization during endocytosis is regulated by cell type–specific and cargo-specific modulators. PMID:27605705

  6. Peptide mimetics of immunoglobulin A (IgA) and FcαRI block IgA-induced human neutrophil activation and migration.

    PubMed

    Heineke, Marieke H; van der Steen, Lydia P E; Korthouwer, Rianne M; Hage, J Joris; Langedijk, Johannes P M; Benschop, Joris J; Bakema, Jantine E; Slootstra, Jerry W; van Egmond, Marjolein

    2017-07-24

    The cross-linking of the IgA Fc receptor (FcαRI) by IgA induces release of the chemoattractant LTB4, thereby recruiting neutrophils in a positive feedback loop. IgA autoantibodies of patients with autoimmune blistering skin diseases therefore induce massive recruitment of neutrophils, resulting in severe tissue damage. To interfere with neutrophil mobilization and reduce disease morbidity, we developed a panel of specific peptides mimicking either IgA or FcαRI sequences. CLIPS technology was used to stabilize three-dimensional structures and to increase peptides' half-life. IgA and FcαRI peptides reduced phagocytosis of IgA-coated beads, as well as IgA-induced ROS production and neutrophil migration in in vitro and ex vivo (human skin) experiments. Since topical application would be the preferential route of administration, Cetomacrogol cream containing an IgA CLIPS peptide was developed. In the presence of a skin permeation enhancer, peptides in this cream were shown to penetrate the skin, while not diffusing systemically. Finally, epitope mapping was used to discover sequences important for binding between IgA and FcαRI. In conclusion, a cream containing IgA or FcαRI peptide mimetics, which block IgA-induced neutrophil activation and migration in the skin may have therapeutic potential for patients with IgA-mediated blistering skin diseases. © 2017 The Authors. European Journal of Immunology published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Altered object-in-place recognition memory, prepulse inhibition, and locomotor activity in the offspring of rats exposed to a viral mimetic during pregnancy.

    PubMed

    Howland, J G; Cazakoff, B N; Zhang, Y

    2012-01-10

    Infection during pregnancy (i.e., prenatal infection) increases the risk of psychiatric illnesses such as schizophrenia and autism in the adult offspring. The present experiments examined the effects of prenatal immune challenge on behavior in three paradigms relevant to these disorders: prepulse inhibition (PPI) of the acoustic startle response, locomotor responses to an unfamiliar environment and the N-methyl-d-aspartate antagonist MK-801, and three forms of recognition memory. Pregnant Long-Evans rats were exposed to the viral mimetic polyinosinic-polycytidylic acid (PolyI:C; 4 mg/kg, i.v.) on gestational day 15. Offspring were tested for PPI and locomotor activity before puberty (postnatal days (PNDs)35 and 36) and during young adulthood (PNDs 56 and 57). Four prepulse-pulse intervals (30, 50, 80, and 140 ms) were employed in the PPI test. Recognition memory testing was performed using three different spontaneous novelty recognition tests (object, object location, and object-in-place recognition) after PND 60. Regardless of sex, offspring of PolyI:C-treated dams showed disrupted PPI at 50-, 80-, and 140-ms prepulse-pulse intervals. In the prepubescent rats, we observed prepulse facilitation for the 30-ms prepulse-pulse interval trials that was selectively retained in the adult PolyI:C-treated offspring. Locomotor responses to MK-801 were significantly reduced before puberty, whereas responses to an unfamiliar environment were increased in young adulthood. Both male and female PolyI:C-treated offspring showed intact object and object location recognition memory, whereas male PolyI:C-treated offspring displayed significantly impaired object-in-place recognition memory. Females were unable to perform the object-in-place test. The present results demonstrate that prenatal immune challenge during mid/late gestation disrupts PPI and locomotor behavior. In addition, the selective impairment of object-in-place recognition memory suggests tasks that depend on prefrontal

  8. Antifreeze (glyco)protein mimetic behavior of poly(vinyl alcohol): detailed structure ice recrystallization inhibition activity study.

    PubMed

    Congdon, Thomas; Notman, Rebecca; Gibson, Matthew I

    2013-05-13

    This manuscript reports a detailed study on the ability of poly(vinyl alcohol) to act as a biomimetic surrogate for antifreeze(glyco)proteins, with a focus on the specific property of ice-recrystallization inhibition (IRI). Despite over 40 years of study, the underlying mechanisms that govern the action of biological antifreezes are still poorly understood, which is in part due to their limited availability and challenging synthesis. Poly(vinyl alcohol) (PVA) has been shown to display remarkable ice recrystallization inhibition activity despite its major structural differences to native antifreeze proteins. Here, controlled radical polymerization is used to synthesize well-defined PVA, which has enabled us to obtain the first quantitative structure-activity relationships, to probe the role of molecular weight and comonomers on IRI activity. Crucially, it was found that IRI activity is "switched on" when the polymer chain length increases from 10 and 20 repeat units. Substitution of the polymer side chains with hydrophilic or hydrophobic units was found to diminish activity. Hydrophobic modifications to the backbone were slightly more tolerated than side chain modifications, which implies an unbroken sequence of hydroxyl units is necessary for activity. These results highlight that, although hydrophobic domains are key components of IRI activity, the random inclusion of addition hydrophobic units does not guarantee an increase in activity and that the actual polymer conformation is important.

  9. Neural ECM mimetics.

    PubMed

    Estrada, Veronica; Tekinay, Ayse; Müller, Hans Werner

    2014-01-01

    The consequence of numerous neurological disorders is the significant loss of neural cells, which further results in multilevel dysfunction or severe functional deficits. The extracellular matrix (ECM) is of tremendous importance for neural regeneration mediating ambivalent functions: ECM serves as a growth-promoting substrate for neurons but, on the other hand, is a major constituent of the inhibitory scar, which results from traumatic injuries of the central nervous system. Therefore, cell and tissue replacement strategies on the basis of ECM mimetics are very promising therapeutic interventions. Numerous synthetic and natural materials have proven effective both in vitro and in vivo. The closer a material's physicochemical and molecular properties are to the original extracellular matrix, the more promising its effectiveness may be. Relevant factors that need to be taken into account when designing such materials for neural repair relate to receptor-mediated cell-matrix interactions, which are dependent on chemical and mechanical sensing. This chapter outlines important characteristics of natural and synthetic ECM materials (scaffolds) and provides an overview of recent advances in design and application of ECM materials for neural regeneration, both in therapeutic applications and in basic biological research.

  10. Presynaptic Muscarinic Acetylcholine Receptors and TrkB Receptor Cooperate in the Elimination of Redundant Motor Nerve Terminals during Development

    PubMed Central

    Nadal, Laura; Garcia, Neus; Hurtado, Erica; Simó, Anna; Tomàs, Marta; Lanuza, Maria A.; Cilleros, Victor; Tomàs, Josep

    2017-01-01

    The development of the nervous system involves the overproduction of synapses but connectivity is refined by Hebbian activity-dependent axonal competition. The newborn skeletal muscle fibers are polyinnervated but, at the end of the competition process, some days later, become innervated by a single axon. We used quantitative confocal imaging of the autofluorescent axons from transgenic B6.Cg-Tg (Thy1-YFP)16 Jrs/J mice to investigate the possible cooperation of the muscarinic autoreceptors (mAChR, M1-, M2- and M4-subtypes) and the tyrosine kinase B (TrkB) receptor in the control of axonal elimination after the mice Levator auris longus (LAL) muscle had been exposed to several selective antagonist of the corresponding receptor pathways in vivo. Our previous results show that M1, M2 and TrkB signaling individually increase axonal loss rate around P9. Here we show that although the M1 and TrkB receptors cooperate and add their respective individual effects to increase axonal elimination rate even more, the effect of the M2 receptor is largely independent of both M1 and TrkB receptors. Thus both, cooperative and non-cooperative signaling mechanisms contribute to developmental synapse elimination. PMID:28228723

  11. Treating diabetes and obesity with an FGF21-mimetic antibody activating the βKlotho/FGFR1c receptor complex.

    PubMed

    Foltz, Ian N; Hu, Sylvia; King, Chadwick; Wu, Xinle; Yang, Chaofeng; Wang, Wei; Weiszmann, Jennifer; Stevens, Jennitte; Chen, Jiyun Sunny; Nuanmanee, Noi; Gupte, Jamila; Komorowski, Renee; Sekirov, Laura; Hager, Todd; Arora, Taruna; Ge, Hongfei; Baribault, Helene; Wang, Fen; Sheng, Jackie; Karow, Margaret; Wang, Minghan; Luo, Yongde; McKeehan, Wallace; Wang, Zhulun; Véniant, Murielle M; Li, Yang

    2012-11-28

    Fibroblast growth factor 21 (FGF21) is a distinctive member of the FGF family with potent beneficial effects on lipid, body weight, and glucose metabolism and has attracted considerable interest as a potential therapeutic for treating diabetes and obesity. As an alternative to native FGF21, we have developed a monoclonal antibody, mimAb1, that binds to βKlotho with high affinity and specifically activates signaling from the βKlotho/FGFR1c (FGF receptor 1c) receptor complex. In obese cynomolgus monkeys, injection of mimAb1 led to FGF21-like metabolic effects, including decreases in body weight, plasma insulin, triglycerides, and glucose during tolerance testing. Mice with adipose-selective FGFR1 knockout were refractory to FGF21-induced improvements in glucose metabolism and body weight. These results in obese monkeys (with mimAb1) and in FGFR1 knockout mice (with FGF21) demonstrated the essential role of FGFR1c in FGF21 function and suggest fat as a critical target tissue for the cytokine and antibody. Because mimAb1 depends on βKlotho to activate FGFR1c, it is not expected to induce side effects caused by activating FGFR1c alone. The unexpected finding of an antibody that can activate FGF21-like signaling through cell surface receptors provided preclinical validation for an innovative therapeutic approach to diabetes and obesity.

  12. Postsynaptic localization of PSD-95 is regulated by all three pathways downstream of TrkB signaling.

    PubMed

    Yoshii, Akira; Constantine-Paton, Martha

    2014-01-01

    Brain-derived neurotrophic factor (BDNF) and its receptor TrkB regulate synaptic plasticity. TrkB triggers three downstream signaling pathways; Phosphatidylinositol 3-kinase (PI3K), Phospholipase Cγ (PLCγ) and Mitogen activated protein kinases/Extracellular signal-regulated kinases (MAPK/ERK). We previously showed two distinct mechanisms whereby BDNF-TrkB pathway controls trafficking of PSD-95, which is the major scaffold at excitatory synapses and is critical for synapse maturation. BDNF activates the PI3K-Akt pathway and regulates synaptic delivery of PSD-95 via vesicular transport (Yoshii and Constantine-Paton, 2007). BDNF-TrkB signaling also triggers PSD-95 palmitoylation and its transport to synapses through the phosphorylation of the palmitoylation enzyme ZDHHC8 by a protein kinase C (PKC; Yoshii etal., 2011). The second study used PKC inhibitors chelerythrine as well as a synthetic zeta inhibitory peptide (ZIP) which was originally designed to block the brain-specific PKC isoform protein kinase Mϖ (PKMϖ). However, recent studies raise concerns about specificity of ZIP. Here, we assessed the contribution of TrkB and its three downstream pathways to the synaptic distribution of endogenous PSD-95 in cultured neurons using chemical and genetic interventions. We confirmed that TrkB, PLC, and PI3K were critical for the postsynaptic distribution of PSD-95. Furthermore, suppression of MAPK/ERK also disrupted PSD-95 expression. Next, we examined the contribution of PKC. While both chelerythrine and ZIP suppressed the postsynaptic localization of PSD-95, RNA interference for PKMϖ did not have a significant effect. This result suggests that the ZIP peptide, widely used as the "specific" PKMϖ antagonist by many investigators may block a PKC variant other than PKMϖ such as PKCλ/ι. Our results indicate that TrkB regulates postsynaptic localization of PSD-95 through all three downstream pathways, but also recommend further work to identify other PKC variants that

  13. RGTA OTR4120, a heparan sulfate mimetic, is a possible long-term active agent to heal burned skin.

    PubMed

    Garcia-Filipe, S; Barbier-Chassefiere, V; Alexakis, C; Huet, E; Ledoux, D; Kerros, M E; Petit, E; Barritault, D; Caruelle, J P; Kern, P

    2007-01-01

    Burn-related skin fibrosis leads to loss of tissue function and hypertrophic scar formation with damaging consequences for the patient. There is therefore a great need for an efficient agent to treat burned skin. We report that ReGeneraTing Agent (RGTA) reduces burn-induced skin alteration. The tissue-regenerating effect of RGTA OTR4120 was evaluated after 1-6 days and after 10 months in a rat skin burn model. This effect was also examined in vitro using fibroblasts isolated from control and 6-day-old burned skins. We measured production of dermal collagen I, III, and V and activities of metalloproteinases 2 and 9 (MMP-2 and MMP-9). Ratio of collagen III over collagen I production increased 6 days after the burn, because of a decrease in collagen I production. After 10 months, ratio of collagen III over collagen I in burn sites was still increased compared with control skin, because of an increase in collagen III production. Both abnormalities were corrected by OTR4120. OTR4120 increased pro- and active MMP-2 and MMP-9, compared with healthy and burned controls and therefore accelerated remodeling. Similar data were obtained with cultured fibroblasts from healthy and burned skins. OTR4120 enhanced healing in short- and long-term after burns, reducing the formation of fibrotic tissue, and then represents a potential agent to improve burned skin healing.

  14. LIM kinase 1 (LIMK1) interacts with tropomyosin-related kinase B (TrkB) and Mediates brain-derived neurotrophic factor (BDNF)-induced axonal elongation.

    PubMed

    Dong, Qing; Ji, Yun-Song; Cai, Chang; Chen, Zhe-Yu

    2012-12-07

    BDNF/TrkB signaling plays critical roles in axonal outgrowth of neurons, the process of which requires the remodeling of the cytoskeleton structure, including microtubules and filamentous actin. However, the mechanism by which BDNF/TrkB signaling regulates cytoskeleton reorganization is still unclear. Here, we identified a novel interaction between LIMK1 and TrkB, which is required for the BDNF-induced axonal elongation. We demonstrated that BDNF-induced TrkB dimerization led to LIMK1 dimerization and transphosphorylation independent of TrkB kinase activity, which could further enhance the activation and stabilization of LIMK1. Moreover, activated LIMK1 translocated to the membrane fraction and phosphorylated its substrate cofilin, thus promoting actin polymerization and axonal elongation. Our findings provided evidence of a novel mechanism for the BDNF-mediated signal transduction leading to axonal elongation.

  15. Protein tyrosine phosphatase 1B (PTP1B) inhibitors from Morinda citrifolia (Noni) and their insulin mimetic activity.

    PubMed

    Nguyen, Phi-Hung; Yang, Jun-Li; Uddin, Mohammad N; Park, So-Lim; Lim, Seong-Il; Jung, Da-Woon; Williams, Darren R; Oh, Won-Keun

    2013-11-22

    As part of our ongoing search for new antidiabetic agents from medicinal plants, we found that a methanol extract of Morinda citrifolia showed potential stimulatory effects on glucose uptake in 3T3-L1 adipocyte cells. Bioassay-guided fractionation of this active extract yielded two new lignans (1 and 2) and three new neolignans (9, 10, and 14), as well as 10 known compounds (3-8, 11-13, and 15). The absolute configurations of compounds 9, 10, and 14 were determined by ECD spectra analysis. Compounds 3, 6, 7, and 15 showed inhibitory effects on PTP1B enzyme with IC50 values of 21.86 ± 0.48, 15.01 ± 0.20, 16.82 ± 0.42, and 4.12 ± 0.09 μM, respectively. Furthermore, compounds 3, 6, 7, and 15 showed strong stimulatory effects on 2-NBDG uptake in 3T3-L1 adipocyte cells. This study indicated the potential of compounds 3, 6, 7, and 15 as lead molecules for antidiabetic agents.

  16. Insulin-mimetic selaginellins from Selaginella tamariscina with protein tyrosine phosphatase 1B (PTP1B) inhibitory activity.

    PubMed

    Nguyen, Phi-Hung; Zhao, Bing-Tian; Ali, Md Yousof; Choi, Jae-Sue; Rhyu, Dong-Young; Min, Byung-Sun; Woo, Mi-Hee

    2015-01-23

    As part of an ongoing search for new antidiabetic agents from medicinal plants, three new (2, 4, and 5) and two known selaginellin derivatives (1 and 3) were isolated from a methanol extract of Selaginella tamariscina. The structures of the new compounds were determined by spectroscopic data analysis. All isolates showed strong glucose uptake stimulatory effects in 3T3-L1 adipocyte cells at a concentration of 5 μM. Furthermore, these compounds were found to possess inhibitory effects on PTP1B enzyme activity with IC50 values ranging from 4.6 ± 0.1 to 21.6 ± 1.5 μM. Compound 2 showed the greatest potency, with an IC50 value of 4.6 ± 0.1 μM, when compared with the positive control (ursolic acid, IC50 = 3.5 ± 0.1 μM). Therefore, these selaginellin derivatives may have value as new lead compounds for the development of agents against type 2 diabetes.

  17. Bio-mimetic surface engineering of plasmid-loaded nanoparticles for active intracellular trafficking by actin comet-tail motility.

    PubMed

    Ng, Chee Ping; Goodman, Thomas T; Park, In-Kyu; Pun, Suzie H

    2009-02-01

    Intracellular transport after endosomal escape presents one of the major barriers for efficient non-viral gene delivery because plasmid DNA and synthetic nanoparticulate carriers suffer from significantly restricted diffusion in the cytoplasm. We postulate that forces generated by actin polymerization, a mechanism used by several bacterial pathogens such as Listeria monocytogenes, can be harnessed to propel nanoparticles within the cytoplasm and thereby overcome diffusional limitations associated with gene transport in the cell cytoplasm. In this work, we synthesized and characterized plasmid DNA-containing nanoparticles modified with ActA protein, the single protein in L. monocytogenes responsible for activating actin polymerization and initiating actin comet-tail propulsion. The motility of the ActA-modified nanoparticles was assessed in Xenopus laevis cytoplasmic extract supplemented with fluorescently labeled actin. Nanoparticle motility was monitored using multi-color, time-lapse fluorescence microscopy for the formation of actin comet tails attached to the fluorescently labeled vehicle. We observed particle motility with velocities approximately 0.06 microm/s with anionic-charged plasmid carriers formed from either poly(lactic-co-glycolic acid) (PLGA) or 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes, but interestingly not with cationic particles assembled by encapsulation of plasmid with either polyethylenimine (PEI) or 1,2-dioleoyl-3-trimethylammonium-propane/1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOTAP/DOPE) lipids. Control particles coated with albumin instead of ActA also showed no motility. Taken together, we have demonstrated the feasibility of translating the comet-tail propulsion mechanism to synthetic drug carriers as a potential approach to overcome intracellular transport barriers, and also have identified appropriate gene delivery systems that can be employed for this mechanism.

  18. TrkB signalling pathways in LTP and learning.

    PubMed

    Minichiello, Liliana

    2009-12-01

    Understanding the mechanisms that underlie learning is one of the most fascinating and central aims of neurobiological research. Hippocampal long-term potentiation (LTP) is widely regarded as a prime candidate for the cellular mechanism of learning. The receptor tyrosine kinase TrkB (also known as NTRK2), known primarily for its function during PNS and CNS development, has emerged in recent years as a potent regulator of hippocampal LTP. Here I describe efforts to understand the signalling pathways and molecular mechanisms that underlie the involvement of TrkB in LTP and learning.

  19. Bio-mimetic Flow Control

    NASA Astrophysics Data System (ADS)

    Choi, Haecheon

    2009-11-01

    Bio-mimetic engineering or bio-mimetics is the application of biological methods and systems found in nature to the study and design of engineering systems and modern technology (from Wikipedia). The concept itself is old, but successful developments have been made recently, especially in the research field of flow control. The objective of flow control based on the bio-mimetic approach is to develop novel concepts for reducing drag, increasing lift and enhancing aerodynamic performance. For skin friction reduction, a few ideas have been suggested such as the riblet from shark, compliant surface from dolphin, microbubble injection and multiple front-body curvature from penguin, and V-shaped protrusion from sailfish. For form drag reduction, several new attempts have been also made recently. Examples include the V-shaped spanwise grooves from saguaro cactus, overall shape of box fish, longitudinal grooves on scallop shell, bill of swordfish, hooked comb on owl wing, trailing-edge protrusion on dragonfly wing, and fillet. For the enhancement of aerodynamic performance, focuses have been made on the birds, fish and insects: e.g., double layered feather of landing bird, leading-edge serration of humpback-whale flipper, pectoral fin of flying fish, long tail on swallowtail-butterfly wing, wing flapping motion of dragonfly, and alula in birds. Living animals adapt their bodies to better performance in multi purposes, but engineering requires single purpose in most cases. Therefore, bio-mimetic approaches often produce excellent results more than expected. However, they are sometimes based on people's wrong understanding of nature and produce unwanted results. Successes and failures from bio-mimetic approaches in flow control will be discussed in the presentation.

  20. Sigma-1 receptor enhances neurite elongation of cerebellar granule neurons via TrkB signaling.

    PubMed

    Kimura, Yuriko; Fujita, Yuki; Shibata, Kumi; Mori, Megumi; Yamashita, Toshihide

    2013-01-01

    Sigma-1 receptor (Sig-1R) is an integral membrane protein predominantly expressed in the endoplasmic reticulum. Sig-1R demonstrates a high affinity to various synthetic compounds including well-known psychotherapeutic drugs in the central nervous system (CNS). For that, it is considered as an alternative target for psychotherapeutic drugs. On the cellular level, when Sig-1R is activated, it is known to play a role in neuroprotection and neurite elongation. These effects are suggested to be mediated by its ligand-operated molecular chaperone activity, and/or upregulation of various Ca(2+) signaling. In addition, recent studies show that Sig-1R activation induces neurite outgrowth via neurotrophin signaling. Here, we tested the hypothesis that Sig-1R activation promotes neurite elongation through activation of tropomyosin receptor kinase (Trk), a family of neurotrophin receptors. We found that 2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate (PRE-084), a selective Sig-1R agonist, significantly promoted neurite outgrowth, and K252a, a Trk inhibitor, attenuated Sig-1R-mediated neurite elongation in cerebellar granule neurons (CGNs). Moreover, we revealed that Sig-1R interacts with TrkB, and PRE-084 treatment enhances phosphorylation of Y515, but not Y706. Thus, our results indicate that Sig-1R activation promotes neurite outgrowth in CGNs through Y515 phosphorylation of TrkB.

  1. Sigma-1 Receptor Enhances Neurite Elongation of Cerebellar Granule Neurons via TrkB Signaling

    PubMed Central

    Kimura, Yuriko; Fujita, Yuki; Shibata, Kumi; Mori, Megumi; Yamashita, Toshihide

    2013-01-01

    Sigma-1 receptor (Sig-1R) is an integral membrane protein predominantly expressed in the endoplasmic reticulum. Sig-1R demonstrates a high affinity to various synthetic compounds including well-known psychotherapeutic drugs in the central nervous system (CNS). For that, it is considered as an alternative target for psychotherapeutic drugs. On the cellular level, when Sig-1R is activated, it is known to play a role in neuroprotection and neurite elongation. These effects are suggested to be mediated by its ligand-operated molecular chaperone activity, and/or upregulation of various Ca2+ signaling. In addition, recent studies show that Sig-1R activation induces neurite outgrowth via neurotrophin signaling. Here, we tested the hypothesis that Sig-1R activation promotes neurite elongation through activation of tropomyosin receptor kinase (Trk), a family of neurotrophin receptors. We found that 2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate (PRE-084), a selective Sig-1R agonist, significantly promoted neurite outgrowth, and K252a, a Trk inhibitor, attenuated Sig-1R-mediated neurite elongation in cerebellar granule neurons (CGNs). Moreover, we revealed that Sig-1R interacts with TrkB, and PRE-084 treatment enhances phosphorylation of Y515, but not Y706. Thus, our results indicate that Sig-1R activation promotes neurite outgrowth in CGNs through Y515 phosphorylation of TrkB. PMID:24116072

  2. Protein-tyrosine phosphatase 1B (PTP1B) is a novel regulator of central brain-derived neurotrophic factor and tropomyosin receptor kinase B (TrkB) signaling.

    PubMed

    Ozek, Ceren; Kanoski, Scott E; Zhang, Zhong-Yin; Grill, Harvey J; Bence, Kendra K

    2014-11-14

    Neuronal protein-tyrosine phosphatase 1B (PTP1B) deficiency in mice results in enhanced leptin signaling and protection from diet-induced obesity; however, whether additional signaling pathways in the brain contribute to the metabolic effects of PTP1B deficiency remains unclear. Here, we show that the tropomyosin receptor kinase B (TrkB) receptor is a direct PTP1B substrate and implicate PTP1B in the regulation of the central brain-derived neurotrophic factor (BDNF) signaling. PTP1B interacts with activated TrkB receptor in mouse brain and human SH-SY5Y neuroblastoma cells. PTP1B overexpression reduces TrkB phosphorylation and activation of downstream signaling pathways, whereas PTP1B inhibition augments TrkB signaling. Notably, brains of Ptpn1(-/-) mice exhibit enhanced TrkB phosphorylation, and Ptpn1(-/-) mice are hypersensitive to central BDNF-induced increase in core temperature. Taken together, our findings demonstrate that PTP1B is a novel physiological regulator of TrkB and that enhanced BDNF/TrkB signaling may contribute to the beneficial metabolic effects of PTP1B deficiency.

  3. APOE-mimetic peptides reduce behavioral deficits, plaques and tangles in Alzheimer's disease transgenics.

    PubMed

    Vitek, M P; Christensen, D J; Wilcock, D; Davis, J; Van Nostrand, W E; Li, F Q; Colton, C A

    2012-01-01

    After age, the second largest risk factor for Alzheimer's disease (AD) is apolipoprotein E (APOE) genotype, where APOE4 is associated with lower apoE protein levels, more severer brain pathology, enhanced inflammation and disease. Small peptides corresponding to the receptor-binding region of apoE mimic the anti-inflammatory activity of the apoE holoprotein. These apoE mimetics greatly improve behavioral outcomes and neuronal survival in head trauma models that display AD pathology and neuronal loss. To determine whether apoE mimetics change behavior, inflammation and pathology in CVND-AD (SwDI-APP/NOS2(-/-)) transgenic mice. Starting at 9 months, apoE peptides were subcutaneously administered 3 times per week for 3 months followed by behavioral, histochemical and biochemical testing. Treatment with apoE mimetics significantly improved behavior while decreasing the inflammatory cytokine IL-6, neurofibrillary tangle-like and amyloid plaque-like structures. Biochemical measures matched the visible pathological results. Treatment with apoE mimetics significantly improved behavior, reduced inflammation and reduced pathology in CVND-AD mice. These improvements are associated with apoE-mimetic-mediated increases in protein phosphatase 2A activity. Testing in additional AD models showed similar benefits, reinforcing this novel mechanism of action of apoE mimetics. These data suggest that the combination of anti-inflammatory and neuroprotective activities of apoE mimetics represents a new generation of potential therapeutics for AD. Copyright © 2012 S. Karger AG, Basel.

  4. Expression and localisation of BDNF, NT4 and TrkB in proliferative vitreoretinopathy.

    PubMed

    Ghazi-Nouri, Seyed M S; Ellis, James S; Moss, Stephen; Limb, G Astrid; Charteris, David G

    2008-05-01

    Exogenous brain derived neurotrophic factor (BDNF) is known to rescue ganglion cell death after optic nerve injury. Its mechanism of action is believed to be indirect via glial cells in the retina. In this study we investigated the changes in expression and localisation of BDNF, neurotrophin-4 (NT4) and their common receptor (TrkB) in retinectomy sections of patients with proliferative vitreoretinopathy (PVR). Nine full-thickness retinectomy specimens obtained at retinal reattachment surgery for PVR were fixed in 4% paraformaldehyde immediately after excision and compared to similarly processed normal donor retinas (4 eyes). Agarose-embedded sections (100 microm thick) were double labelled for immunohistochemistry by confocal microscopy, with antibodies against BDNF, NT4, TrkB, rod opsin, glial fibrillary acidic protein (GFAP), cellular retinaldehyde binding protein (CRALBP) and Brn3. This study demonstrates expression of NT4 by ganglion cells and shows expression of BDNF and NT4 in the outer photoreceptor segments is downregulated during PVR, whilst NT4 is markedly upregulated throughout the retina during this condition. The findings here suggest that NT4 may play a neural protective role during the development of PVR. It also shows that upregulation of NT4 in PVR is localised to Müller glial cells, indicating either over-expression of this factor by Müller cells or that Müller cells internalise NT4 for trafficking across the retina. TrkB expression was not observed in PVR retina. The observations that Müller glia demonstrate upregulation of NT4 suggests that retinal injury may lead to activation of this neurotrophin by Müller cells as part of their neuroprotective functions.

  5. Exercise, fasting, and mimetics: toward beneficial combinations?

    PubMed

    Jaspers, Richard T; Zillikens, M Carola; Friesema, Edith C H; delli Paoli, Giuseppe; Bloch, Wilhelm; Uitterlinden, André G; Goglia, Fernando; Lanni, Antonia; de Lange, Pieter

    2017-01-01

    Obesity and type 2 diabetes are associated disorders that involve a multiplicity of tissues. Both fasting and physical exercise are known to counteract dyslipidemia/hyperglycemia. Skeletal muscle plays a key role in the control of blood glucose levels, and the metabolic changes and related signaling pathways in skeletal muscle induced by fasting overlap with those induced by exercise. The reduction of fat disposal has been shown to extend to the liver and to white and brown adipose tissue and to involve an increase in their metabolic activities. In recent years signal transduction pathways related to exercise and fasting/food withdrawal in muscle have been intensively studied, both in animals and in humans. Combining fasting/food withdrawal with exercise in animals as well as in humans causes changes unlike those seen during fasting/food withdrawal or exercise alone, which favor repair of muscle over autophagy. In addition, compounds that mimic exercise have been studied in combination with exercise or fasting/food withdrawal. This review addresses our current knowledge of the mechanisms that underlie the individual and combined effects of fasting/food withdrawal, endurance or resistance exercise, and their mimetics, in muscle vs other organs in rodents and humans, and highlights which combinations may improve metabolic disorders.-Jaspers, R. T., Zillikens, M. C., Friesema, E. C. H., delli Paoli, G., Bloch, W., Uitterlinden, A. G., Goglia, F., Lanni, A., de Lange, P. Exercise, fasting, and mimetics: toward beneficial combinations.

  6. Immunolocalization of pro- and mature-brain derived neurotrophic factor (BDNF) and receptor TrkB in the human brainstem and hippocampus.

    PubMed

    Tang, Samantha; Machaalani, Rita; Waters, Karen A

    2010-10-01

    Brain-derived neurotrophic factor (BDNF) and its receptor TrkB are essential in promoting normal development of the central nervous system. Specific functions that are affected in knockout models include respiratory control, coordination of movement and balance, and feeding activities. The expression of these markers has not yet been studied in the human infant brain. This study provides a detailed account of the distribution and localization of both pro- and mature-recombinant human (rh) forms of BDNF, and of TrkB in the human infant brainstem and hippocampus, and qualitatively compares this expression to that seen in the human adult. Using commercially available antibodies, we applied immunohistochemistry on formalin fixed and paraffin embedded human brain tissue [n=8 for infant, n=6 for adult], and qualitatively analyzed the expression of proBDNF, rhBDNF and TrkB. Amongst the brainstem regions studied, the greatest expression of the markers was in the mesencephalic trigeminal of the pons, and in the medulla, the inferior olive and arcuate nucleus. The lowest expression was in the substantia nigra of the midbrain and pontine locus coeruleus. Compared to adults, all the studied markers had a higher expression in the infant brainstem nuclei of the hypoglossal, vestibular, dorsal motor nucleus of the vagus, prepositus, cuneate, and dorsal raphe. In the hippocampus, only TrkB showed a higher expression in infants compared to adults. We conclude that BDNF and TrkB play important roles in controlling respiration, movement, balance and feeding in the brainstem and that the TrkB receptor is the most age-sensitive component of this system, especially in the hippocampus.

  7. A novel mimetic antigen eliciting protective antibody to Neisseria meningitidis.

    PubMed

    Granoff, D M; Moe, G R; Giuliani, M M; Adu-Bobie, J; Santini, L; Brunelli, B; Piccinetti, F; Zuno-Mitchell, P; Lee, S S; Neri, P; Bracci, L; Lozzi, L; Rappuoli, R

    2001-12-01

    Molecular mimetic Ags are of considerable interest as vaccine candidates. Yet there are few examples of mimetic Ags that elicit protective Ab against a pathogen, and the functional activity of anti-mimetic Abs has not been studied in detail. As part of the Neisseria meningitidis serogroup B genome sequencing project, a large number of novel proteins were identified. Herein, we provide evidence that genome-derived Ag 33 (GNA33), a lipoprotein with homology to Escherichia coli murein transglycosylase, elicits protective Ab to meningococci as a result of mimicking an epitope on loop 4 of porin A (PorA) in strains with serosubtype P1.2. Epitope mapping of a bactericidal anti-GNA33 mAb using overlapping peptides shows that the mAb recognizes peptides from GNA33 and PorA that share a QTP sequence that is necessary but not sufficient for binding. By flow cytometry, mouse antisera prepared against rGNA33 and the anti-GNA33 mAb bind as well as an anti-PorA P1.2 mAb to the surface of eight of nine N. meningitidis serogroup B strains tested with the P1.2 serosubtype. Anti-GNA33 Abs also are bactericidal for most P1.2 strains and, for susceptible strains, the activity of an anti-GNA33 mAb is similar to that of an anticapsular mAb but less active than an anti-P1.2 mAb. Anti-GNA Abs also confer passive protection against bacteremia in infant rats challenged with P1.2 strains. Thus, GNA33 represents one of the most effective immunogenic mimetics yet described. These results demonstrate that molecular mimetics have potential as meningococcal vaccine candidates.

  8. ABT-199, a BH3 mimetic that specifically targets Bcl-2, enhances the antitumor activity of chemotherapy, bortezomib and JQ1 in "double hit" lymphoma cells.

    PubMed

    Johnson-Farley, Nadine; Veliz, Jonny; Bhagavathi, S; Bertino, Joseph R

    2015-07-01

    Double hit lymphoma (DHL) is a recently recognized lymphoma with a survival of less than 2 years. Both ABT-737, a Bcl-2/Bcl-XL inhibitor, and ABT-199, which selectively targets Bcl-2, were potently cytotoxic against DHL cell lines Sc-1 and OcI-LY18, the RL cell line and primary human DHL cells, but not Ramos cells, which lack Bcl-2 expression. ABT-199 was more potent than ABT-737, and is the most promising of the BH3 mimetics to date. The DHL cell lines were also sensitive (< 200 nM) to doxorubicin, methotrexate, cytarabine and the proteosome inhibitor, bortezomib. The combination of chemotherapy with ABT-199 and doxorubicin or cytarabine, bortezomib, YM-155 and JQ1 produced synergistic cell kill against the DHL cell lines. Cells from a patient with DHL were also sensitive to JQ1 and bortezomib, providing a rationale for a clinical trial of these combinations in patients with relapsed DHL.

  9. Endocannabinoids regulate interneuron migration and morphogenesis by transactivating the TrkB receptor.

    PubMed

    Berghuis, Paul; Dobszay, Marton B; Wang, Xinyu; Spano, Sabrina; Ledda, Fernanda; Sousa, Kyle M; Schulte, Gunnar; Ernfors, Patrik; Mackie, Ken; Paratcha, Gustavo; Hurd, Yasmin L; Harkany, Tibor

    2005-12-27

    In utero exposure to Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the active component from marijuana, induces cognitive deficits enduring into adulthood. Although changes in synaptic structure and plasticity may underlie Delta(9)-THC-induced cognitive impairments, the neuronal basis of Delta(9)-THC-related developmental deficits remains unknown. Using a Boyden chamber assay, we show that agonist stimulation of the CB(1) cannabinoid receptor (CB(1)R) on cholecystokinin-expressing interneurons induces chemotaxis that is additive with brain-derived neurotrophic factor (BDNF)-induced interneuron migration. We find that Src kinase-dependent TrkB receptor transactivation mediates endocannabinoid (eCB)-induced chemotaxis in the absence of BDNF. Simultaneously, eCBs suppress the BDNF-dependent morphogenesis of interneurons, and this suppression is abolished by Src kinase inhibition in vitro. Because sustained prenatal Delta(9)-THC stimulation of CB(1)Rs selectively increases the density of cholecystokinin-expressing interneurons in the hippocampus in vivo, we conclude that prenatal CB(1)R activity governs proper interneuron placement and integration during corticogenesis. Moreover, eCBs use TrkB receptor-dependent signaling pathways to regulate subtype-selective interneuron migration and specification.

  10. Repeated stress increases catalytic TrkB mRNA in rat hippocampus.

    PubMed

    Nibuya, M; Takahashi, M; Russell, D S; Duman, R S

    1999-05-28

    Northern blot analysis was utilized to distinguish between catalytic and truncated TrkB mRNA on the basis of transcript size. Repeated (10 days), but not acute, immobilization stress significantly increased levels of catalytic TrkB mRNA, but did not influence expression of truncated TrkB transcripts in rat hippocampus. Exposure to another paradigm, a combination of different, unpredictable stressors, also increased levels of catalytic, but not truncated, TrkB mRNA. In situ hybridization analysis demonstrated that chronic stress up-regulated TrkB mRNA in CA1 and CA3 pyramidal and dentate gyrus granule cells layers of hippocampus. As previously reported, both acute and chronic immobilization stress decreased expression of BDNF mRNA, suggesting that up-regulation of catalytic TrkB mRNA may be a compensatory adaptation to repeated stress.

  11. Impaired TrkB Signaling Underlies Reduced BDNF-Mediated Trophic Support of Striatal Neurons in the R6/2 Mouse Model of Huntington’s Disease

    PubMed Central

    Nguyen, Khanh Q.; Rymar, Vladimir V.; Sadikot, Abbas F.

    2016-01-01

    The principal projection neurons of the striatum are critically dependent on an afferent supply of brain derived neurotrophic factor (BDNF) for neurotrophic support. These neurons express TrkB, the cognate receptor for BDNF, which activates signaling pathways associated with neuronal survival and phenotypic maintenance. Impairment of the BDNF-TrkB pathway is suspected to underlie the early dysfunction and prominent degeneration of striatal neurons in Huntington disease (HD). Some studies in HD models indicate that BDNF supply is reduced, while others suggest that TrkB signaling is impaired earlier in disease progression. It remains important to determine whether a primary defect in TrkB signaling underlies reduced neurotrophic support and the early vulnerability of striatal neurons in HD. Using the transgenic R6/2 mouse model of HD we found that prior to striatal degeneration there are early deficits in striatal protein levels of activated phospho-TrkB and the downstream-regulated protein DARPP-32. In contrast, total-TrkB and BDNF protein levels remained normal. Primary neurons cultured from R6/2 striatum exhibited reduced survival in response to exogenous BDNF applications. Moreover, BDNF activation of phospho-TrkB and downstream signal transduction was attenuated in R6/2 striatal cultures. These results suggest that neurotrophic support of striatal neurons is attenuated early in disease progression due to defects in TrkB signal transduction in the R6/2 model of HD. PMID:27013968

  12. Functional DNA methylation in a transcript specific 3′UTR region of TrkB associates with suicide

    PubMed Central

    Maussion, Gilles; Yang, Jennie; Suderman, Matthew; Diallo, Alpha; Nagy, Corina; Arnovitz, Mitchell; Mechawar, Naguib; Turecki, Gustavo

    2014-01-01

    Previous studies indicate that a subgroup of suicide completers has low cortical brain expression levels of TrkB-T1, a TrkB gene transcript that is highly expressed in astrocytes. Epigenetic modifications, including methylation changes in the TrkB promoter, partially explain TrkB-T1 low expression levels in brain tissue from suicide completers. The aim of this study was to investigate whether methylation changes in other regions of the TrkB gene could also contribute to the significant downregulation of the TrkB-T1 transcript observed in the brain of suicide completers. Methylation levels were assessed on BA8/9 from suicide completers expressing low TrkB-T1 transcript levels and controls, using custom-made Agilent arrays tiling the whole TrkB gene. After statistical correction for multiple testing, five probes located in the TrkB-T1 3′UTR region were found hypermethylated in the frontal cortex of suicide completers. These results were validated for four CpGs spanning a 150 bp sequence by cloning and Sanger sequencing bisulfite treated DNA. We found a significant correlation between the methylation level at these four CpGs and TrkB-T1 expression in BA8/9. Site-specific hypermethylation on this 3′UTR sequence induced decreased luciferase activity in reporter gene cell assays. Site-specific differential methylation in the TrkB-T1 3′UTR region associates with functional changes in TrkB-T1 expression and may play a significant role in the important decrease of cortical TrkB-T1 expression observed among suicide completers. PMID:24802768

  13. Interfacing membrane mimetics with mass spectrometry

    PubMed Central

    Marty, Michael T.; Hoi, Kin Kuan; Robinson, Carol V.

    2017-01-01

    Conspectus Membrane proteins play critical physiological roles and make up the majority of drug targets. Due to their generally low expression levels and amphipathic nature, membrane proteins represent challenging molecular entities for biophysical study. Mass spectrometry offers several sensitive approaches to study the biophysics of membrane proteins. By preserving noncovalent interactions in the gas phase and using collisional activation to remove solubilization agents inside the mass spectrometer, native mass spectrometry (MS) is capable of studying isolated assemblies that would be insoluble in aqueous solution, such as membrane protein oligomers and protein-lipid complexes. Conventional methods use detergent to solubilize the protein prior to electrospray ionization. Gas-phase activation inside the mass spectrometer removes the detergent to yield the isolated proteins with bound ligands. This approach has proven highly successful for ionizing membrane proteins. With the appropriate choice of detergents, membrane proteins with bound lipid species can be observed, which allows characterization of protein-lipid interactions. However, detergents have several limitations. They do not necessarily replicate the native lipid bilayer environment, and only a small number of protein-lipid interactions can be resolved. In this Account, we summarize the development of different membrane mimetics as cassettes for MS analysis of membrane proteins. Examples include amphipols, bicelles, and picodiscs with a special emphasis on lipoprotein Nanodiscs. Polydispersity and heterogeneity of the membrane mimetic cassette is a critical issue for study by MS. Ever more complex datasets consisting of overlapping protein charge states and multiple lipid-bound entities have required development of new computational, theoretical, and experimental approaches to interpret both mass and ion mobility spectra. We will present the rationale and limitations of these approaches. Starting with the

  14. Modulation of BDNF and TrkB expression in rat hippocampus in response to acute neurotoxicity by diethyldithiocarbamate.

    PubMed

    Micheli, M R; Bova, R; Laurenzi, M A; Bazzucchi, M; Grassi Zucconi, G

    2006-12-13

    In this study, we examined the expression profile of brain-derived neurotrophic factor (BDNF) and its receptor TrkB in adult rat hippocampus following acute administration of diethyldithiocarbamate (DDTC), a neurotoxic compound which was previously shown to induce microglia activation and cell death. Semiquantitative RT-PCR analysis detected significant variations of BDNF mRNA levels in whole hippocampus homogenates, with a peak at 24h after DDTC injection. Increased BDNF protein expression was demonstrated by immunohistochemistry in various hippocampal subfields. The most relevant increase was observed in the hilus of the dentate gyrus where BDNF levels at 120h were found to be almost four times those of basal levels. Full-length TrkB (TrkB.FL) encoding mRNA was also shown to undergo an earlier increase in the hippocampus of DDTC-treated rats. TrkB immunostaining with an antibody binding both full-length and truncated (TrkB.T) isoforms was found to increase at 120h in the hippocampal CA2 and CA3 regions. These results demonstrate that DDTC modulates the expression of BDNF and its receptor in the adult rat hippocampus and suggest a possible involvement of this neurotrophin in the protective response to DDTC-induced neuronal damage.

  15. Upregulation of TrkB by forskolin facilitated survival of MSC and functional recovery of memory deficient model rats.

    PubMed

    Heo, Hwon; Yoo, Minjoo; Han, Donghoon; Cho, Yakdol; Joung, Insil; Kwon, Yunhee Kim

    2013-02-22

    Mesenchymal stem cells (MSCs) are effective vectors in delivering a gene of interest into degenerating brain. In ex vivo gene therapy, viability of transplanted MSCs is correlated with the extent of functional recovery. It has been reported that BDNF facilitates survival of MSCs but dividing MSCs do not express the BDNF receptor, TrkB. In this study, we found that the expression of TrkB is upregulated in human MSCs by the addition of forskolin (Fsk), an activator of adenylyl cyclase. To increase survival rate of MSCs and their secretion of tropic factors that enhance regeneration of endogenous cells, we pre-exposed hMSCs with Fsk and transduced with BDNF-adenovirus before transplantation into the brain of memory deficient rats, a degenerating brain disease model induced by ibotenic acid injection. Viability of MSCs and expression of a GABA synthesizing enzyme were increased. The pre-treatment improved learning and memory, as detected by the behavioral tests including Y-maze task and passive avoidance test. These results suggest that TrkB expression of hMSCs elevates the neuronal regeneration and efficiency of BDNF delivery for treating degenerative neurological diseases accompanying memory loss.

  16. The Small-Molecule TrkB Agonist 7, 8-Dihydroxyflavone Decreases Hippocampal Newborn Neuron Death After Traumatic Brain Injury.

    PubMed

    Chen, Liang; Gao, Xiang; Zhao, Shu; Hu, Weipeng; Chen, Jinhui

    2015-06-01

    Previous studies in rodents have shown that after a moderate traumatic brain injury (TBI) with a controlled cortical impact (CCI) device, the adult-born immature granular neurons in the dentate gyrus are the most vulnerable cell type in the hippocampus. There is no effective approach for preventing immature neuron death after TBI. We found that tyrosine-related kinase B (TrkB), a receptor of brain-derived neurotrophic factor (BDNF), is highly expressed in adult-born immature neurons. We determined that the small molecule imitating BDNF, 7, 8-dihydroxyflavone (DHF), increased phosphorylation of TrkB in immature neurons both in vitro and in vivo. Pretreatment with DHF protected immature neurons from excitotoxicity-mediated death in vitro, and systemic administration of DHF before moderate CCI injury reduced the death of adult-born immature neurons in the hippocampus 24 hours after injury. By contrast, inhibiting BDNF signaling using the TrkB antagonist ANA12 attenuated the neuroprotective effects of DHF. These data indicate that DHF may be a promising chemical compound that promotes immature neuron survival after TBI through activation of the BDNF signaling pathway.

  17. Sulforaphane epigenetically enhances neuronal BDNF expression and TrkB signaling pathways.

    PubMed

    Kim, Jisung; Lee, Siyoung; Choi, Bo-Ryoung; Yang, Hee; Hwang, Youjin; Park, Jung Han Yoon; LaFerla, Frank M; Han, Jung-Soo; Lee, Ki Won; Kim, Jiyoung

    2017-02-01

    Brain-derived neurotrophic factor (BDNF) is a neurotrophin that supports the survival of existing neurons and encourages the growth and differentiation of new neurons and synapses. We investigated the effect of sulforaphane, a hydrolysis product of glucoraphanin present in Brassica vegetables, on neuronal BDNF expression and its synaptic signaling pathways. Mouse primary cortical neurons and a triple-transgenic mouse model of Alzheimer's disease (3 × Tg-AD) were used to study the effect of sulforaphane. Sulforaphane enhanced neuronal BDNF expression and increased levels of neuronal and synaptic molecules such as MAP2, synaptophysin, and PSD-95 in primary cortical neurons and 3 × Tg-AD mice. Sulforaphane elevated levels of synaptic TrkB signaling pathway components, including CREB, CaMKII, ERK, and Akt in both primary cortical neurons and 3 × Tg-AD mice. Sulforaphane increased global acetylation of histone 3 (H3) and H4, inhibited HDAC activity, and decreased the level of HDAC2 in primary cortical neurons. Chromatin immunoprecipitation analysis revealed that sulforaphane increased acetylated H3 and H4 at BDNF promoters, suggesting that sulforaphane regulates BDNF expression via HDAC inhibition. These findings suggest that sulforaphane has the potential to prevent neuronal disorders such as Alzheimer's disease by epigenetically enhancing neuronal BDNF expression and its TrkB signaling pathways. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Caloric restriction mimetics: towards a molecular definition.

    PubMed

    Madeo, Frank; Pietrocola, Federico; Eisenberg, Tobias; Kroemer, Guido

    2014-10-01

    Caloric restriction, be it constant or intermittent, is reputed to have health-promoting and lifespan-extending effects. Caloric restriction mimetics (CRMs) are compounds that mimic the biochemical and functional effects of caloric restriction. In this Opinion article, we propose a unifying definition of CRMs as compounds that stimulate autophagy by favouring the deacetylation of cellular proteins. This deacetylation process can be achieved by three classes of compounds that deplete acetyl coenzyme A (AcCoA; the sole donor of acetyl groups), that inhibit acetyl transferases (a group of enzymes that acetylate lysine residues in an array of proteins) or that stimulate the activity of deacetylases and hence reverse the action of acetyl transferases. A unifying definition of CRMs will be important for the continued development of this class of therapeutic agents.

  19. Laminin mimetic peptide nanofibers regenerate acute muscle defect.

    PubMed

    Eren Cimenci, Cagla; Uzunalli, Gozde; Uysal, Ozge; Yergoz, Fatih; Karaca Umay, Ebru; Guler, Mustafa O; Tekinay, Ayse B

    2017-09-15

    Skeletal muscle cells are terminally differentiated and require the activation of muscle progenitor (satellite) cells for their regeneration. There is a clinical need for faster and more efficient treatment methods for acute muscle injuries, and the stimulation of satellite cell proliferation is promising in this context. In this study, we designed and synthesized a laminin-mimetic bioactive peptide (LM/E-PA) system that is capable of accelerating satellite cell activation by emulating the structure and function of laminin, a major protein of the basal membrane of the skeletal muscle. The LM/E-PA nanofibers enhance myogenic differentiation in vitro and the clinical relevance of the laminin-mimetic bioactive scaffold system was demonstrated further by assessing its effect on the regeneration of acute muscle injury in a rat model. Laminin mimetic peptide nanofibers significantly promoted satellite cell activation in skeletal muscle and accelerated myofibrillar regeneration following acute muscle injury. In addition, the LM/E-PA scaffold treatment significantly reduced the time required for the structural and functional repair of skeletal muscle. This study represents one of the first examples of molecular- and tissue-level regeneration of skeletal muscle facilitated by bioactive peptide nanofibers following acute muscle injury. Sports, heavy lifting and other strength-intensive tasks are ubiquitous in modern life and likely to cause acute skeletal muscle injury. Speeding up regeneration of skeletal muscle injuries would not only shorten the duration of recovery for the patient, but also support the general health and functionality of the repaired muscle tissue. In this work, we designed and synthesized a laminin-mimetic nanosystem to enhance muscle regeneration. We tested its activity in a rat tibialis anterior muscle by injecting the bioactive nanosystem. The evaluation of the regeneration and differentiation capacity of skeletal muscle suggested that the laminin-mimetic

  20. How sound symbolism is processed in the brain: a study on Japanese mimetic words.

    PubMed

    Kanero, Junko; Imai, Mutsumi; Okuda, Jiro; Okada, Hiroyuki; Matsuda, Tetsuya

    2014-01-01

    Sound symbolism is the systematic and non-arbitrary link between word and meaning. Although a number of behavioral studies demonstrate that both children and adults are universally sensitive to sound symbolism in mimetic words, the neural mechanisms underlying this phenomenon have not yet been extensively investigated. The present study used functional magnetic resonance imaging to investigate how Japanese mimetic words are processed in the brain. In Experiment 1, we compared processing for motion mimetic words with that for non-sound symbolic motion verbs and adverbs. Mimetic words uniquely activated the right posterior superior temporal sulcus (STS). In Experiment 2, we further examined the generalizability of the findings from Experiment 1 by testing another domain: shape mimetics. Our results show that the right posterior STS was active when subjects processed both motion and shape mimetic words, thus suggesting that this area may be the primary structure for processing sound symbolism. Increased activity in the right posterior STS may also reflect how sound symbolic words function as both linguistic and non-linguistic iconic symbols.

  1. How Sound Symbolism Is Processed in the Brain: A Study on Japanese Mimetic Words

    PubMed Central

    Okuda, Jiro; Okada, Hiroyuki; Matsuda, Tetsuya

    2014-01-01

    Sound symbolism is the systematic and non-arbitrary link between word and meaning. Although a number of behavioral studies demonstrate that both children and adults are universally sensitive to sound symbolism in mimetic words, the neural mechanisms underlying this phenomenon have not yet been extensively investigated. The present study used functional magnetic resonance imaging to investigate how Japanese mimetic words are processed in the brain. In Experiment 1, we compared processing for motion mimetic words with that for non-sound symbolic motion verbs and adverbs. Mimetic words uniquely activated the right posterior superior temporal sulcus (STS). In Experiment 2, we further examined the generalizability of the findings from Experiment 1 by testing another domain: shape mimetics. Our results show that the right posterior STS was active when subjects processed both motion and shape mimetic words, thus suggesting that this area may be the primary structure for processing sound symbolism. Increased activity in the right posterior STS may also reflect how sound symbolic words function as both linguistic and non-linguistic iconic symbols. PMID:24840874

  2. A small molecule TrkB ligand reduces motor impairment and neuropathology in R6/2 and BACHD mouse models of Huntington's disease.

    PubMed

    Simmons, Danielle A; Belichenko, Nadia P; Yang, Tao; Condon, Christina; Monbureau, Marie; Shamloo, Mehrdad; Jing, Deqiang; Massa, Stephen M; Longo, Frank M

    2013-11-27

    Loss of neurotrophic support in the striatum caused by reduced brain-derived neurotrophic factor (BDNF) levels plays a critical role in Huntington's disease (HD) pathogenesis. BDNF acts via TrkB and p75 neurotrophin receptors (NTR), and restoring its signaling is a prime target for HD therapeutics. Here we sought to determine whether a small molecule ligand, LM22A-4, specific for TrkB and without effects on p75(NTR), could alleviate HD-related pathology in R6/2 and BACHD mouse models of HD. LM22A-4 was administered to R6/2 mice once daily (5-6 d/week) from 4 to 11 weeks of age via intraperitoneal and intranasal routes simultaneously to maximize brain levels. The ligand reached levels in the R6/2 forebrain greater than the maximal neuroprotective dose in vitro and corrected deficits in activation of striatal TrkB and its key signaling intermediates AKT, PLCγ, and CREB. Ligand-induced TrkB activation was associated with a reduction in HD pathologies in the striatum including decreased DARPP-32 levels, neurite degeneration of parvalbumin-containing interneurons, inflammation, and intranuclear huntingtin aggregates. Aggregates were also reduced in the cortex. Notably, LM22A-4 prevented deficits in dendritic spine density of medium spiny neurons. Moreover, R6/2 mice given LM22A-4 demonstrated improved downward climbing and grip strength compared with those given vehicle, though these groups had comparable rotarod performances and survival times. In BACHD mice, long-term LM22A-4 treatment (6 months) produced similar ameliorative effects. These results support the hypothesis that targeted activation of TrkB inhibits HD-related degenerative mechanisms, including spine loss, and may provide a disease mechanism-directed therapy for HD and other neurodegenerative conditions.

  3. A Small Molecule TrkB Ligand Reduces Motor Impairment and Neuropathology in R6/2 and BACHD Mouse Models of Huntington's Disease

    PubMed Central

    Simmons, Danielle A.; Belichenko, Nadia P.; Yang, Tao; Condon, Christina; Monbureau, Marie; Shamloo, Mehrdad; Jing, Deqiang; Massa, Stephen M.

    2013-01-01

    Loss of neurotrophic support in the striatum caused by reduced brain-derived neurotrophic factor (BDNF) levels plays a critical role in Huntington's disease (HD) pathogenesis. BDNF acts via TrkB and p75 neurotrophin receptors (NTR), and restoring its signaling is a prime target for HD therapeutics. Here we sought to determine whether a small molecule ligand, LM22A-4, specific for TrkB and without effects on p75NTR, could alleviate HD-related pathology in R6/2 and BACHD mouse models of HD. LM22A-4 was administered to R6/2 mice once daily (5–6 d/week) from 4 to 11 weeks of age via intraperitoneal and intranasal routes simultaneously to maximize brain levels. The ligand reached levels in the R6/2 forebrain greater than the maximal neuroprotective dose in vitro and corrected deficits in activation of striatal TrkB and its key signaling intermediates AKT, PLCγ, and CREB. Ligand-induced TrkB activation was associated with a reduction in HD pathologies in the striatum including decreased DARPP-32 levels, neurite degeneration of parvalbumin-containing interneurons, inflammation, and intranuclear huntingtin aggregates. Aggregates were also reduced in the cortex. Notably, LM22A-4 prevented deficits in dendritic spine density of medium spiny neurons. Moreover, R6/2 mice given LM22A-4 demonstrated improved downward climbing and grip strength compared with those given vehicle, though these groups had comparable rotarod performances and survival times. In BACHD mice, long-term LM22A-4 treatment (6 months) produced similar ameliorative effects. These results support the hypothesis that targeted activation of TrkB inhibits HD-related degenerative mechanisms, including spine loss, and may provide a disease mechanism-directed therapy for HD and other neurodegenerative conditions. PMID:24285878

  4. Corticosterone regulates expression of BDNF and trkB but not NT-3 and trkC mRNA in the rat hippocampus.

    PubMed

    Schaaf, M J; Hoetelmans, R W; de Kloet, E R; Vreugdenhil, E

    1997-05-15

    Corticosterone has profound effects on growth, differentiation, and synaptic transmission of hippocampal neurons by activation of mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs). In the present study we tested if neurotrophins can be implicated in these effects. For this purpose we injected 30, 300, and 1,000 microg corticosterone s.c. (per kg body weight) in adrenalectomized rats and measured the mRNA levels of brain-derived neurotrophic factor (BDNF), tyrosine receptor kinase (trk)B, neurotrophin (NT)-3, and trkC in hippocampal cell fields at 6 hr after steroid administration by in situ hybridization. NT-3 and trkC mRNA did not show significant changes in any hippocampal region after the various doses of corticosterone. BDNF mRNA decreased after corticosterone administration dose dependently, resulting in a maximal suppression of 35, 20, and 50% in dentate gyrus, CA3, and CA1, respectively. Interestingly, trkB responded to corticosterone in an inverted U-shaped fashion in CA3 and dentate gyrus: the low dose of corticosterone increased trkB mRNA expression in both regions by approximately 30%, while the effect of the two higher doses was not different from the vehicle injected controls. In conclusion, we found differential effects of low and high doses of corticosterone on BDNF and trkB expression in hippocampus, which suggests involvement of a coordinated MR- and GR-mediated action.

  5. ApoA-I mimetics.

    PubMed

    Stoekenbroek, R M; Stroes, E S; Hovingh, G K

    2015-01-01

    A wealth of evidence indicates that plasma levels of high-density lipoprotein cholesterol (HDL-C) are inversely related to the risk of cardiovascular disease (CVD). Consequently, HDL-C has been considered a target for therapy in order to reduce the residual CVD burden that remains significant, even after application of current state-of-the-art medical interventions. In recent years, however, a number of clinical trials of therapeutic strategies that increase HDL-C levels failed to show the anticipated beneficial effect on CVD outcomes. As a result, attention has begun to shift toward strategies to improve HDL functionality, rather than levels of HDL-C per se. ApoA-I, the major protein component of HDL, is considered to play an important role in many of the antiatherogenic functions of HDL, most notably reverse cholesterol transport (RCT), and several therapies have been developed to mimic apoA-I function, including administration of apoA-I, mutated variants of apoA-I, and apoA-I mimetic peptides. Based on the potential anti-inflammatory effects, apoA-I mimetics hold promise not only as anti-atherosclerotic therapy but also in other therapeutic areas.

  6. Colitis elicits differential changes in the expression levels of receptor tyrosine kinase TrkA and TrkB in colonic afferent neurons: A possible involvement of axonal transport

    PubMed Central

    Qiao, Li-Ya; Grider, John R

    2010-01-01

    The role of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in colitis-induced hypersensitivity has been suggested. NGF and BDNF facilitate cellular physiology through binding to receptor tyrosine kinase TrkA and TrkB respectively. The present study by examining the mRNA and/or protein levels of TrkA and TrkB in the distal colon and in colonic primary afferent neurons in the dorsal root ganglia (DRG) during colitis demonstrated that colitis elicited location-specific changes in the mRNA and protein levels of TrkA and TrkB in colonic primary sensory pathways. In colitis both the TrkA and TrkB protein levels were increased in the L1 and S1 DRGs in a time-dependent manner; however, the level of TrkB mRNA but not TrkA mRNA was increased in these DRGs. Further experiments showed that colitis facilitated a retrograde transport of TrkA protein toward and an anterograde transport of TrkA mRNA away from the DRG, which may contribute to the increased TrkA mRNA level in the distal colon during colitis. Colitis also increased the level of NGF mRNA but not BDNF mRNA in the distal colon. Double staining showed that the expression of TrkA but not TrkB was increased in the specifically labeled colonic afferent neurons in the L1 and S1 DRGs during colitis; this increase in TrkA level was attenuated by pretreatment with resiniferatoxin. These results suggested that colitis-induced primary afferent activation involved retrograde transport of TrkA but not TrkB from the distal colon to primary afferent neurons in DRG. PMID:20638179

  7. A Novel Peptide Thrombopoietin Mimetic Designing and Optimization Using Computational Approach

    PubMed Central

    Singh, Vimal Kishor; Kumar, Neeraj; Kalsan, Manisha; Saini, Abhishek; Chandra, Ramesh

    2016-01-01

    Thrombopoietin receptor (TPOR) is a cytokine receptor protein present on the cell surface. The activation of TPOR by thrombopoietin (TPO) (a glycoprotein hormone) triggers an intracellular cascade of megakaryocytopoiesis for the formation of platelets. Recent studies on ex vivo megakaryocytopoiesis have evolved the possibilities of therapeutics uses. These findings have paved the way for the development of various TPO alternatives (recombinant TPO, peptide, and non-peptide TPO mimetics), which are useful in regenerative medicine. However, these alternatives possess various limitations such as induction of autoimmune effects, high production cost, low specificity, and hence activity. In the present study, a novel peptidic TPO mimetic was designed through computational studies by studying the binding sites of TPO and TMP to TPOR and analogs of known mimetics. Screening of combinatorial library was done through molecular docking using ClusPro. These studies indicated mimetic-9 as a significant molecule since it was found to have better binding score of −938.8 kcal/mol with seven hydrogen bonds and a high number of hydrophobic interactions, than known mimetic TMP with docking score of −798.4 kcal/mol and TMP dimer with docking score of −811.9 kcal/mol for TPOR. Mimetic9-TPOR complex was further assessed by the molecular dynamics simulation, and their complex was found to be stable with an RMSD value of 0.091 Å. While studying the parameters, mimetic-9 was found to have overall good physiochemical properties with positive grand average hydropathy (GRAVY) score and high instability index score and was found to be localized in the extracellular region. The designed mimetic-9 might prove to be a useful lead molecule for mimicking the role of TPO for in vitro platelet production with higher efficiency. PMID:27630985

  8. BDNF up-regulates TrkB protein and prevents the death of CA1 neurons following transient forebrain ischemia.

    PubMed

    Ferrer, I; Ballabriga, J; Martí, E; Pérez, E; Alberch, J; Arenas, E

    1998-04-01

    The neurotrophin family of growth factors, which includes Nerve Growth Factor (NGF), Brain-Derived Neurotrophic Factor (BDNF), Neurotrophin-3 (NT3) and Neurotrophin-4/5 (NT4/5) bind and activate specific tyrosine kinase (Trk) receptors to promote cell survival and growth of different cell populations. For these reasons, growing attention has been paid to the use of neurotrophins as therapeutic agents in neurodegeneration, and to the regulation of the expression of their specific receptors by the ligands. BDNF expression, as revealed by immunohistochemistry, is found in the pre-subiculum, CA1, CA3, and dentate gyrus of the hippocampus. Strong TrkB immunoreactivity is present in most CA3 neurons but only in scattered neurons of the CA1 area. Weak TrkB immunoreactivity is found in the granule cell layer of the dentate gyrus. Unilateral grafting of BDNF-transfected fibroblasts into the hippocampus resulted in a marked increase in the intensity of the immunoreaction and in the number of TrkB-immunoreactive neurons in the granule cell layer of the dentate gyrus, pre-subiculum and CA1 area in the vicinity of the graft. No similar effects were produced after the injection of control mock-transfected fibroblasts. Delayed cell death in the CA1 area was produced following 5 min of forebrain ischemia in the gerbil. The majority of living cells in the CA1 area at the fourth day were BDNF/TrkB immunoreactive. Unilateral grafting of control mock-transfected or BDNF fibroblasts two days before ischemia resulted in a moderate non-specific protection of TrkB-negative, but not TrkB-positive cells, in the CA1 area of the grafted side. This finding is in line with a vascular and glial reaction, as revealed, by immunohistochemistry using astroglial and microglial cell markers. This astroglial response was higher in the grafted side than in the contralateral side in ischemic gerbils, but no differences were seen between BDNF-producing and non-BDNF-producing grafts. However, grafting of

  9. Up-regulation of dorsal root ganglia BDNF and trkB receptor in inflammatory pain: an in vivo and in vitro study

    PubMed Central

    2011-01-01

    -regulated trkB expression in DRG cultures. Conclusions Based on our current experimental results, we conclude that inflammation and TNF-α up-regulate the BDNF-trkB system in DRG. This phenomenon suggests that up-regulation of BDNF in DRG may, in addition to its post-synaptic effect in spinal dorsal horn, act as an autocrine and/or paracrine signal to activate the pre-synaptic trkB receptor and regulate synaptic excitability in pain transmission, thereby contributing to the development of hyperalgesia. PMID:21958434

  10. TrkB Receptor Signalling: Implications in Neurodegenerative, Psychiatric and Proliferative Disorders

    PubMed Central

    Gupta, Vivek K.; You, Yuyi; Gupta, Veer Bala; Klistorner, Alexander; Graham, Stuart L.

    2013-01-01

    The Trk family of receptors play a wide variety of roles in physiological and disease processes in both neuronal and non-neuronal tissues. Amongst these the TrkB receptor in particular has attracted major attention due to its critical role in signalling for brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and neurotrophin-4 (NT4). TrkB signalling is indispensable for the survival, development and synaptic plasticity of several subtypes of neurons in the nervous system. Substantial evidence has emerged over the last decade about the involvement of aberrant TrkB signalling and its compromise in various neuropsychiatric and degenerative conditions. Unusual changes in TrkB signalling pathway have also been observed and implicated in a range of cancers. Variations in TrkB pathway have been observed in obesity and hyperphagia related disorders as well. Both BDNF and TrkB have been shown to play critical roles in the survival of retinal ganglion cells in the retina. The ability to specifically modulate TrkB signalling can be critical in various pathological scenarios associated with this pathway. In this review, we discuss the mechanisms underlying TrkB signalling, disease implications and explore plausible ameliorative or preventive approaches. PMID:23670594

  11. TrkB receptor signalling: implications in neurodegenerative, psychiatric and proliferative disorders.

    PubMed

    Gupta, Vivek K; You, Yuyi; Gupta, Veer Bala; Klistorner, Alexander; Graham, Stuart L

    2013-05-13

    The Trk family of receptors play a wide variety of roles in physiological and disease processes in both neuronal and non-neuronal tissues. Amongst these the TrkB receptor in particular has attracted major attention due to its critical role in signalling for brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and neurotrophin-4 (NT4). TrkB signalling is indispensable for the survival, development and synaptic plasticity of several subtypes of neurons in the nervous system. Substantial evidence has emerged over the last decade about the involvement of aberrant TrkB signalling and its compromise in various neuropsychiatric and degenerative conditions. Unusual changes in TrkB signalling pathway have also been observed and implicated in a range of cancers. Variations in TrkB pathway have been observed in obesity and hyperphagia related disorders as well. Both BDNF and TrkB have been shown to play critical roles in the survival of retinal ganglion cells in the retina. The ability to specifically modulate TrkB signalling can be critical in various pathological scenarios associated with this pathway. In this review, we discuss the mechanisms underlying TrkB signalling, disease implications and explore plausible ameliorative or preventive approaches.

  12. CD4-mimetic sulfopeptide conjugates display sub-nanomolar anti-HIV-1 activity and protect macaques against a SHIV162P3 vaginal challenge

    PubMed Central

    Ariën, Kevin K.; Baleux, Françoise; Desjardins, Delphine; Porrot, Françoise; Coïc, Yves-Marie; Michiels, Johan; Bouchemal, Kawthar; Bonnaffé, David; Bruel, Timothée; Schwartz, Olivier; Le Grand, Roger; Vanham, Guido; Dereuddre-Bosquet, Nathalie; Lortat-Jacob, Hugues

    2016-01-01

    The CD4 and the cryptic coreceptor binding sites of the HIV-1 envelope glycoprotein are key to viral attachment and entry. We developed new molecules comprising a CD4 mimetic peptide linked to anionic compounds (mCD4.1-HS12 and mCD4.1-PS1), that block the CD4-gp120 interaction and simultaneously induce the exposure of the cryptic coreceptor binding site, rendering it accessible to HS12- or PS1- mediated inhibition. Using a cynomolgus macaque model of vaginal challenge with SHIV162P3, we report that mCD4.1-PS1, formulated into a hydroxyethyl-cellulose gel provides 83% protection (5/6 animals). We next engineered the mCD4 moiety of the compound, giving rise to mCD4.2 and mCD4.3 that, when conjugated to PS1, inhibited cell-free and cell-associated HIV-1 with particularly low IC50, in the nM to pM range, including some viral strains that were resistant to the parent molecule mCD4.1. These chemically defined molecules, which target major sites of vulnerability of gp120, are stable for at least 48 hours in conditions replicating the vaginal milieu (37 °C, pH 4.5). They efficiently mimic several large gp120 ligands, including CD4, coreceptor or neutralizing antibodies, to which their efficacy compares very favorably, despite a molecular mass reduced to 5500 Da. Together, these results support the development of such molecules as potential microbicides. PMID:27721488

  13. Synthetic N-acetyl-D-glucosamine based fully branched tetrasaccharide, a mimetic of the endogenous ligand for CD69, activates CD69+ killer lymphocytes upon dimerization via a hydrophilic flexible linker.

    PubMed

    Kovalová, Anna; Ledvina, Miroslav; Saman, David; Zyka, Daniel; Kubícková, Monika; Zídek, Lukás; Sklenár, Vladimír; Pompach, Petr; Kavan, Daniel; Bílý, Jan; Vanek, Ondrej; Kubínková, Zuzana; Libigerová, Martina; Ivanová, Ljubina; Antolíková, Mária; Mrázek, Hynek; Rozbeský, Daniel; Hofbauerová, Katerina; Kren, Vladimír; Bezouska, Karel

    2010-05-27

    On the basis of the highly branched ovomucoid-type undecasaccharide that had been shown previously to be an endogenous ligand for CD69 leukocyte receptor, a systematic investigation of smaller oligosaccharide mimetics was performed based on linear and branched N-acetyl-d-hexosamine homooligomers prepared synthetically using hitherto unexplored reaction schemes. The systematic structure-activity studies revealed the tetrasaccharide GlcNAcbeta1-3(GlcNAcbeta1-4)(GlcNAcbeta1-6)GlcNAc (compound 52) and its alpha-benzyl derivative 49 as the best ligand for CD69 with IC(50) as high as 10(-9) M. This compound thus approaches the affinity of the classical high-affinity neoglycoprotein ligand GlcNAc(23)BSA. Compound 68, GlcNAc tetrasaccharide 52 dimerized through a hydrophilic flexible linker, turned out to be effective in activating CD69(+) lymphocytes. It also proved efficient in enhancing natural killing in vitro, decreasing the growth of tumors in vivo, and activating the CD69(+) tumor infiltrating lymphocytes examined ex vivo. This compound is thus a candidate for carbohydrate-based immunomodulators with promising antitumor potential.

  14. Anti-endotoxic activity and structural basis for human MD-2·TLR4 antagonism of tetraacylated lipid A mimetics based on βGlcN(1↔1)αGlcN scaffold

    PubMed Central

    Garate, Jose Antonio; Stöckl, Johannes; del Carmen Fernández-Alonso, María; Artner, Daniel; Haegman, Mira; Oostenbrink, Chris; Jiménez-Barbero, Jesús; Beyaert, Rudi; Heine, Holger; Kosma, Paul

    2015-01-01

    Interfering with LPS binding by the co-receptor protein myeloid differentiation factor 2 (MD-2) represents a useful approach for down-regulation of MD-2·TLR4-mediated innate immune signaling, which is implicated in the pathogenesis of a variety of human diseases, including sepsis syndrome. The antagonistic activity of a series of novel synthetic tetraacylated bis-phosphorylated glycolipids based on the βGlcN(1↔1)αGlcN scaffold was assessed in human monocytic macrophage-like cell line THP-1, dendritic cells and human epithelial cells. Two compounds were shown to inhibit efficiently the LPS-induced inflammatory signaling by down-regulation of the expression of TNF-α, IL-6, IL-8, IL-10 and IL-12 to background levels. The binding of the tetraacylated by (R)-3-hydroxy-fatty acids (2 × C12, 2 × C14), 4,4′-bisphosphorylated βGlcN(1↔1)αGlcN-based lipid A mimetic DA193 to human MD-2 was calculated to be 20-fold stronger than that of Escherichia coli lipid A. Potent antagonistic activity was related to a specific molecular shape induced by the β,α(1↔1)-diglucosamine backbone. ‘Co-planar’ relative arrangement of the GlcN rings was inflicted by the double exo-anomeric conformation around both glycosidic torsions in the rigid β,α(1↔1) linkage, which was ascertained using NOESY NMR experiments and confirmed by molecular dynamics simulation. In contrast to the native lipid A ligands, the binding affinity of βGlcN(1↔1)αGlcN-based lipid A mimetics to human MD-2 was independent on the orientation of the diglucosamine backbone of the synthetic antagonist within the binding pocket of hMD-2 (rotation by 180°) allowing for two equally efficient binding modes as shown by molecular dynamics simulation. PMID:25394365

  15. Investigating the Efficacy of Novel TrkB Agonists to Augment Stroke Recovery

    NASA Astrophysics Data System (ADS)

    Warraich, Zuha

    Stroke remains the leading cause of adult disability in developed countries. Most survivors live with residual motor impairments that severely diminish independence and quality of life. After stroke, the only accepted treatment for these patients is motor rehabilitation. However, the amount and kind of rehabilitation required to induce clinically significant improvements in motor function is rarely given due to the constraints of our current health care system. Research reported in this dissertation contributes towards developing adjuvant therapies that may augment the impact of motor rehabilitation and improve functional outcome. These studies have demonstrated reorganization of maps within motor cortex as a function of experience in both healthy and brain-injured animals by using intracortical microstimulation technique. Furthermore, synaptic plasticity has been identified as a key neural mechanism in directing motor map plasticity, evidenced by restoration of movement representations within the spared cortical tissue accompanied by increase in synapse number translating into motor improvement after stroke. There is increasing evidence that brain-derived neurotrophic factor (BDNF) modulates synaptic and morphological plasticity in the developing and mature nervous system. Unfortunately, BDNF itself is a poor candidate because of its short half-life, low penetration through the blood brain barrier, and activating multiple receptor units, p75 and TrkB on the neuronal membrane. In order to circumvent this problem efficacy of two recently developed novel TrkB agonists, LM22A-4 and 7,8-dihydroxyflavone, that actively penetrate the blood brain barrier and enhance functional recovery. Findings from these dissertation studies indicate that administration of these pharmacological compounds, accompanied by motor rehabilitation provide a powerful therapeutic tool for stroke recovery.

  16. Small-molecule BH3 mimetic and pan-Bcl-2 inhibitor AT-101 enhances the antitumor efficacy of cisplatin through inhibition of APE1 repair and redox activity in non-small-cell lung cancer

    PubMed Central

    Ren, Tao; Shan, Jinlu; Li, Mengxia; Qing, Yi; Qian, Chengyuan; Wang, Guangjie; Li, Qing; Lu, Guoshou; Li, Chongyi; Peng, Yu; Luo, Hao; Zhang, Shiheng; Yang, Yuxing; Cheng, Yi; Wang, Dong; Zhou, Shu-Feng

    2015-01-01

    AT-101 is a BH3 mimetic and pan-Bcl-2 inhibitor that has shown potent anticancer activity in non-small-cell lung cancer (NSCLC) in murine models, but failed to show clinical efficacy when used in combination with docetaxel in NSCLC patients. Our recent study has demonstrated that AT-101 enhanced the antitumor effect of cisplatin (CDDP) in a murine model of NSCLC via inhibition of the interleukin-6/signal transducer and activator of transcription 3 (STAT3) pathway. This study explored the underlying mechanisms for the enhanced anticancer activity of CDDP by AT-101. Our results show that, when compared with monotherapy, AT-101 significantly enhanced the inhibitory effects of CDDP on proliferation and migration of A549 cells and on tube formation and migration in human umbilical vein endothelial cells. AT-101 promoted the proapoptotic activity of CDDP in A549 cells. AT-101 also enhanced the inhibitory effect of CDDP on DNA repair and redox activities of apurinic/apyrimidinic endonuclease 1 (APE1) in A549 cells. In tumor tissues from nude mice treated with AT-101 plus CDDP or monotherapy, the combination therapy resulted in greater inhibition of angiogenesis and tumor cell proliferation than the monotherapy. These results suggest that AT-101 can enhance the antitumor activity of CDDP in NSCLC via inhibition of APE1 DNA repair and redox activities and by angiogenesis and induction of apoptosis, but other mechanisms cannot be excluded. We are now conducting a Phase II trial to examine the clinical efficacy and safety profile of combined use of AT-101 plus CDDP in advanced NSCLC patients. PMID:26089640

  17. TrkB gene therapy by adeno-associated virus enhances recovery after cervical spinal cord injury.

    PubMed

    Martínez-Gálvez, Gabriel; Zambrano, Juan M; Diaz Soto, Juan C; Zhan, Wen-Zhi; Gransee, Heather M; Sieck, Gary C; Mantilla, Carlos B

    2016-02-01

    Unilateral cervical spinal cord hemisection at C2 (C2SH) interrupts descending bulbospinal inputs to phrenic motoneurons, paralyzing the diaphragm muscle. Recovery after C2SH is enhanced by brain derived neurotrophic factor (BDNF) signaling via the tropomyosin-related kinase subtype B (TrkB) receptor in phrenic motoneurons. The role for gene therapy using adeno-associated virus (AAV)-mediated delivery of TrkB to phrenic motoneurons is not known. The present study determined the therapeutic efficacy of intrapleural delivery of AAV7 encoding for full-length TrkB (AAV-TrkB) to phrenic motoneurons 3 days post-C2SH. Diaphragm EMG was recorded chronically in male rats (n=26) up to 21 days post-C2SH. Absent ipsilateral diaphragm EMG activity was verified 3 days post-C2SH. A greater proportion of animals displayed recovery of ipsilateral diaphragm EMG activity during eupnea by 14 and 21 days post-SH after AAV-TrkB (10/15) compared to AAV-GFP treatment (2/11; p=0.031). Diaphragm EMG amplitude increased over time post-C2SH (p<0.001), and by 14 days post-C2SH, AAV-TrkB treated animals displaying recovery achieved 48% of the pre-injury values compared to 27% in AAV-GFP treated animals. Phrenic motoneuron mRNA expression of glutamatergic AMPA and NMDA receptors revealed a significant, positive correlation (r(2)=0.82), with increased motoneuron NMDA expression evident in animals treated with AAV-TrkB and that displayed recovery after C2SH. Overall, gene therapy using intrapleural delivery of AAV-TrkB to phrenic motoneurons is sufficient to promote recovery of diaphragm activity, adding a novel potential intervention that can be administered after upper cervical spinal cord injury to improve impaired respiratory function.

  18. TrkB Gene Therapy by Adeno-Associated Virus Enhances Recovery after Cervical Spinal Cord Injury

    PubMed Central

    Martínez-Gálvez, Gabriel; Zambrano, Juan M.; Diaz Soto, Juan C.; Zhan, Wen-Zhi; Gransee, Heather M.; Sieck, Gary C.; Mantilla, Carlos B.

    2015-01-01

    Unilateral cervical spinal cord hemisection at C2 (C2SH) interrupts descending bulbospinal inputs to phrenic motoneurons, paralyzing the diaphragm muscle. Recovery after C2SH is enhanced by brain derived neurotrophic factor (BDNF) signaling via the tropomyosin-related kinase subtype B (TrkB) receptor in phrenic motoneurons. The role for gene therapy using adeno-associated virus (AAV)-mediated delivery of TrkB to phrenic motoneurons is not known. The present study determined the therapeutic efficacy of intrapleural delivery of AAV7 encoding for full-length TrkB (AAV-TrkB) to phrenic motoneurons 3 days post-C2SH. Diaphragm EMG was recorded chronically in male rats (n = 26) up to 21 days post-C2SH. Absent ipsilateral diaphragm EMG activity was verified 3 days post-C2SH. A greater proportion of animals displayed recovery of ipsilateral diaphragm EMG activity during eupnea by 14 and 21 days post-SH after AAV-TrkB (10/15) compared to AAV-GFP treatment (2/11; p = 0.031). Diaphragm EMG amplitude increased over time post-C2SH (p < 0.001), and by 14 days post-C2SH, AAV-TrkB treated animals displaying recovery achieved 48% of the pre-injury values compared to 27% in AAV-GFP treated animals. Phrenic motoneuron mRNA expression of glutamatergic AMPA and NMDA receptors revealed a significant, positive correlation (r2 = 0.82), with increased motoneuron NMDA expression evident in animals treated with AAV-TrkB and that displayed recovery after C2SH. Overall, gene therapy using intrapleural delivery of AAV-TrkB to phrenic motoneurons is sufficient to promote recovery of diaphragm activity, adding a novel potential intervention that can be administered after upper cervical spinal cord injury to improve impaired respiratory function. PMID:26607912

  19. Tackling Glaucoma from within the Brain: An Unfortunate Interplay of BDNF and TrkB.

    PubMed

    Dekeyster, Eline; Geeraerts, Emiel; Buyens, Tom; Van den Haute, Chris; Baekelandt, Veerle; De Groef, Lies; Salinas-Navarro, Manuel; Moons, Lieve

    2015-01-01

    According to the neurotrophin deprivation hypothesis, diminished retrograde delivery of neurotrophic support during an early stage of glaucoma pathogenesis is one of the main triggers that induce retinal ganglion cell (RGC) degeneration. Therefore, interfering with neurotrophic signaling seems an attractive strategy to achieve neuroprotection. Indeed, exogenous neurotrophin administration to the eye has been shown to reduce loss of RGCs in animal models of glaucoma; however, the neuroprotective effect was mostly insufficient for sustained RGC survival. We hypothesized that treatment at the level of neurotrophin-releasing brain areas might be beneficial, as signaling pathways activated by target-derived neurotrophins are suggested to differ from pathways that are initiated at the soma membrane. In our study, first, the spatiotemporal course of RGC degeneration was characterized in mice subjected to optic nerve crush (ONC) or laser induced ocular hypertension (OHT). Subsequently, the well-known neurotrophin brain-derived neurotrophic factor (BDNF) was chosen as the lead molecule, and the levels of BDNF and its high-affinity receptor, tropomyosin receptor kinase B (TrkB), were examined in the mouse retina and superior colliculus (SC) upon ONC and OHT. Both models differentially influenced BDNF and TrkB levels. Next, we aimed for RGC protection through viral vector-mediated upregulation of collicular BDNF, thought to boost the retrograde neurotrophin delivery. Although the previously reported temporary neuroprotective effect of intravitreally delivered recombinant BDNF was confirmed, viral vector-induced BDNF overexpression in the SC did not result in protection of the RGCs in the glaucoma models used. These findings most likely relate to decreased neurotrophin responsiveness upon vector-mediated BDNF overexpression. Our results highlight important insights concerning the complexity of neurotrophic factor treatments that should surely be considered in future

  20. Upregulation of TrkB promotes epithelial-mesenchymal transition and anoikis resistance in endometrial carcinoma.

    PubMed

    Bao, Wei; Qiu, Haifeng; Yang, Tingting; Luo, Xin; Zhang, Huijuan; Wan, Xiaoping

    2013-01-01

    Mechanisms governing the metastasis of endometrial carcinoma (EC) are poorly defined. Recent data support a role for the cell surface receptor tyrosine kinase TrkB in the progression of several human tumors. Here we present evidence for a direct role of TrkB in human EC. Immunohistochemical analysis revealed that TrkB and its secreted ligand, brain-derived neurotrophic factor (BDNF), are more highly expressed in EC than in normal endometrium. High TrkB levels correlated with lymph node metastasis (p<0.05) and lymphovascular space involvement (p<0.05) in EC. Depletion of TrkB by stable shRNA-mediated knockdown decreased the migratory and invasive capacity of cancer cell lines in vitro and resulted in anoikis in suspended cells. Conversely, exogenous expression of TrkB increased cell migration and invasion and promoted anoikis resistance in suspension culture. Furthermore, over-expression of TrkB or stimulation by BDNF resulted in altered the expression of molecular mediators of the epithelial-to-mesenchymal transition (EMT). RNA interference (RNAi)-mediated depletion of the downstream regulator, Twist, blocked TrkB-induced EMT-like transformation. The use of in vivo models revealed decreased peritoneal dissemination in TrkB-depleted EC cells. Additionally, TrkB-depleted EC cells underwent mesenchymal-to-epithelial transition and anoikis in vivo. Our data support a novel function for TrkB in promoting EMT and resistance to anoikis. Thus, TrkB may constitute a potential therapeutic target in human EC.

  1. [Incretin mimetic drugs: therapeutic positioning].

    PubMed

    López Simarro, F

    2014-07-01

    Type 2 diabetes is a chronic and complex disease, due to the differences among affected individuals, which affect choice of treatment. The number of drug families has increased in the last few years, and these families have widely differing mechanisms of action, which contributes greatly to the individualization of treatment according to the patient's characteristics and comorbidities. The present article discusses incretin mimetic drugs. Their development has been based on knowledge of the effects of natural incretin hormones: GLP-1 (glucagon-like peptide 1), GIP (glucose-dependent insulinotropic peptide) and dipeptidyl peptidase enzyme 4 (DPP4), which rapidly degrade them in the systemic circulation. This group is composed of 2 different types of molecules: GLP-1 analogs and DPP4 enzyme inhibitors. The benefits of these molecules include a reduction in plasma glucose without the risk of hypoglycemias or weight gain. There are a series of questions that require new studies to establish a possible association between the use of these drugs and notification of cases of pancreatitis, as well as their relationship with pancreatic and thyroid cancer. Also awaited is the publication of several studies that will provide information on the relationship between these drugs and cardiovascular risk in people with diabetes. All these questions will probably be progressively elucidated with greater experience in the use of these drugs. Copyright © 2014 Elsevier España, S.L.U. y Sociedad Española de Medicina Rural y Generalista (SEMERGEN). All rights reserved.

  2. Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus.

    PubMed

    Dolotov, Oleg V; Karpenko, Ekaterina A; Inozemtseva, Lyudmila S; Seredenina, Tamara S; Levitskaya, Natalia G; Rozyczka, Joanna; Dubynina, Elena V; Novosadova, Ekaterina V; Andreeva, Lyudmila A; Alfeeva, Lyudmila Yu; Kamensky, Andrey A; Grivennikov, Igor A; Myasoedov, Nikolay F; Engele, Jürgen

    2006-10-30

    The heptapeptide Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is an analog of the adrenocorticotropin fragment (4-10) which after intranasal application has profound effects on learning and exerts marked neuroprotective activities. Here, we found that a single application of Semax (50 microg/kg body weight) results in a maximal 1.4-fold increase of BDNF protein levels accompanying with 1.6-fold increase of trkB tyrosine phosporylation levels, and a 3-fold and a 2-fold increase of exon III BDNF and trkB mRNA levels, respectively, in the rat hippocampus. Semax-treated animals showed a distinct increase in the number of conditioned avoidance reactions. We suggest that Semax affects cognitive brain functions by modulating the expression and the activation of the hippocampal BDNF/trkB system.

  3. TrkB signaling in parvalbumin-positive interneurons is critical for gamma-band network synchronization in hippocampus.

    PubMed

    Zheng, Kang; An, Juan Ji; Yang, Feng; Xu, Weifeng; Xu, Zhi-Qing David; Wu, Jianyoung; Hökfelt, Tomas G M; Fisahn, André; Xu, Baoji; Lu, Bai

    2011-10-11

    Although brain-derived neurotrophic factor (BDNF) is known to regulate circuit development and synaptic plasticity, its exact role in neuronal network activity remains elusive. Using mutant mice (TrkB-PV(-/-)) in which the gene for the BDNF receptor, tyrosine kinase B receptor (trkB), has been specifically deleted in parvalbumin-expressing, fast-spiking GABAergic (PV+) interneurons, we show that TrkB is structurally and functionally important for the integrity of the hippocampal network. The amplitude of glutamatergic inputs to PV+ interneurons and the frequency of GABAergic inputs to excitatory pyramidal cells were reduced in the TrkB-PV(-/-) mice. Functionally, rhythmic network activity in the gamma-frequency band (30-80 Hz) was significantly decreased in hippocampal area CA1. This decrease was caused by a desynchronization and overall reduction in frequency of action potentials generated in PV+ interneurons of TrkB-PV(-/-) mice. Our results show that the integration of PV+ interneurons into the hippocampal microcircuit is impaired in TrkB-PV(-/-) mice, resulting in decreased rhythmic network activity in the gamma-frequency band.

  4. Expression of BDNF and TrkB Phosphorylation in the Rat Frontal Cortex During Morphine Withdrawal are NO Dependent.

    PubMed

    Peregud, Danil I; Yakovlev, Alexander A; Stepanichev, Mikhail Yu; Onufriev, Mikhail V; Panchenko, Leonid F; Gulyaeva, Natalia V

    2016-08-01

    Nitric oxide (NO) mediates pharmacological effects of opiates including dependence and abstinence. Modulation of NO synthesis during the induction phase of morphine dependence affects manifestations of morphine withdrawal syndrome, though little is known about mechanisms underlying this phenomenon. Neurotrophic and growth factors are involved in neuronal adaptation during opiate dependence. NO-dependent modulation of morphine dependence may be mediated by changes in expression and activity of neurotrophic and/or growth factors in the brain. Here, we studied the effects of NO synthesis inhibition during the induction phase of morphine dependence on the expression of brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), nerve growth factor (NGF), and insulin-like growth factor 1 (IGF1) as well as their receptors in rat brain regions after spontaneous morphine withdrawal in dependent animals. Morphine dependence in rats was induced within 6 days by 12 injections of morphine in increasing doses (10-100 mg/kg), and NO synthase inhibitor L-N(G)-nitroarginine methyl ester (L-NAME) (10 mg/kg) was given 1 h before each morphine injection. The expression of the BDNF, GDNF, NGF, IGF1, and their receptors in the frontal cortex, striatum, hippocampus, and midbrain was assessed 40 h after morphine withdrawal. L-NAME treatment during morphine intoxication resulted in an aggravation of the spontaneous morphine withdrawal severity. Morphine withdrawal was accompanied by upregulation of BDNF, IGF1, and their receptors TrkB and IGF1R, respectively, on the mRNA level in the frontal cortex, and only BDNF in hippocampus and midbrain. L-NAME administration during morphine intoxication decreased abstinence-induced upregulation of these mRNAs in the frontal cortex, hippocampus and midbrain. L-NAME prevented from abstinence-induced elevation of mature but not pro-form of BDNF polypeptide in the frontal cortex. While morphine abstinence did not affect TrkB

  5. TrkB regulates hippocampal neurogenesis and governs sensitivity to antidepressive treatment

    PubMed Central

    Li, Yun; Luikart, Bryan W.; Birnbaum, Shari; Chen, Jian; Kwon, Chang-Hyuk; Kernie, Steven G.; Bassel-Duby, Rhonda; Parada, Luis F.

    2008-01-01

    Summary Adult hippocampal neurogenesis is stimulated by chronic administration of antidepressants (ADs) and by voluntary exercise. Neural progenitor cells in the dentate gyrus (DG) that are capable of continuous proliferation and neuronal differentiation are the source of such structural plasticity. Here we report that mice lacking the receptor tyrosine kinase TrkB in hippocampal NPCs have impaired proliferation and neurogenesis. When exposed to chronic AD or wheel running, no increase in proliferation or neurogenesis is observed. Ablation of TrkB also renders these mice behaviorally insensitive to antidepressive treatment in depression and anxiety-like paradigms. In contrast, mice lacking TrkB only in differentiated DG neurons display typical neurogenesis and respond normally to chronic AD. Thus, our data establish an essential cell autonomous role for TrkB in regulating hippocampal neurogenesis, behavioral sensitivity to antidepressive treatments, and support the notion that impairment of the neurogenic niche is an etiological factor for refractory responses to antidepressive regimen. PMID:18701066

  6. Mitochondrial apoptosis and BH3 mimetics

    PubMed Central

    2016-01-01

    The BCL2-selective BH3 mimetic venetoclax was recently approved for the treatment of relapsed, chromosome 17p-deleted chronic lymphocytic leukemia (CLL) and is undergoing extensive testing, alone and in combination, in lymphomas, acute leukemias, and solid tumors. Here we summarize recent advances in understanding of the biology of BCL2 family members that shed light on the action of BH3 mimetics, review preclinical and clinical studies leading to the regulatory approval of venetoclax, and discuss future investigation of this new class of antineoplastic agent. PMID:27990281

  7. Mitochondrial apoptosis and BH3 mimetics.

    PubMed

    Dai, Haiming; Meng, X Wei; Kaufmann, Scott H

    2016-01-01

    The BCL2-selective BH3 mimetic venetoclax was recently approved for the treatment of relapsed, chromosome 17p-deleted chronic lymphocytic leukemia (CLL) and is undergoing extensive testing, alone and in combination, in lymphomas, acute leukemias, and solid tumors. Here we summarize recent advances in understanding of the biology of BCL2 family members that shed light on the action of BH3 mimetics, review preclinical and clinical studies leading to the regulatory approval of venetoclax, and discuss future investigation of this new class of antineoplastic agent.

  8. Thrombopoietin mimetics for patients with myelodysplastic syndromes.

    PubMed

    Dodillet, Helga; Kreuzer, Karl-Anton; Monsef, Ina; Skoetz, Nicole

    2017-09-30

    Myelodysplastic syndrome (MDS) is one of the most frequent haematologic malignancies of the elderly population and characterised by progenitor cell dysplasia with ineffective haematopoiesis and a high rate of transformation to acute myeloid leukaemia (AML). Thrombocytopenia represents a common problem for patients with MDS. ranging from mild to serious bleeding events and death. To manage thrombocytopenia, the current standard treatment includes platelet transfusion, unfortunately leading to a range of side effects. Thrombopoietin (TPO) mimetics represent an alternative treatment option for MDS patients with thrombocytopenia. However, it remains unclear, whether TPO mimetics influence the increase of blast cells and therefore to premature progression to AML. To evaluate the efficacy and safety of thrombopoietin (TPO) mimetics for patients with MDS. We searched for randomised controlled trials in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (January 2000 to August 2017), trials registries (ISRCTN, EU clinical trials register and clinicaltrials.gov) and conference proceedings. We did not apply any language restrictions. Two review authors independently screened search results, disagreements were solved by discussion. We included randomised controlled trials comparing TPO mimetics with placebo, no further treatment or another TPO mimetic in patients with MDS of all risk groups, without gender, age or ethnicity restrictions. Additional chemotherapeutic treatment had to be equal in both arms. Two review authors independently extracted data and assessed the quality of trials, disagreements were resolved by discussion. Risk ratio (RR) was used to analyse mortality during study, transformation to AML, incidence of bleeding events, transfusion requirement, all adverse events, adverse events >= grade 3, serious adverse events and platelet response. Overall survival (OS) and progression-free survival (PFS) have been extracted as hazard ratios, but

  9. “On Trk” - the TrkB signal transduction pathway is an increasingly important target in cancer biology

    PubMed Central

    Thiele, Carol J.; Li, Zhijie; McKee, Amy E.

    2009-01-01

    In the beginning - Trk was an oncogene. Yet Neurotrophin-Trk signaling came to pre-eminence in the field of neurobiology. Now it is appreciated that Trks regulate important processes in non-neuronal cells and, in addition to their impact on tumors of neural origin, may contribute to the pathogenesis of carcinomas, myelomas, prostate and lymphoid tumors. While mutations and rearrangements of Trk are only sporadically seen in human cancers such as medullary thryoid carcinoma, a number of recent studies indicate that expression of TrkB contributes to tumor pathology. In neuroblastoma TrkA expression marks good prognosis which TrkB and Brain-derived neurotrophic factor (BDNF) expression marks poor prognosis. Activation of the BDNF/TrkB signal transduction pathway also stimulates tumor cell survival and angiogenesis and contributes to resistance to cytotoxic drugs and anoikis, enabling cells to acquire many of the characteristic features required for tumorigenesis. Small molecule inihibitors such as Cephalon's CEP-701 are in Phase I & II clinical trials, and a series of AstraZeneca Trk inhibitors are poised to enter the clinic. As monotherapy, inhibitors may only be effective in tumors with activating Trk mutations. Important clinical follow-up will be the assessment of Trk inhibitors in combination with standard chemo- or radiotherapy or other signal transduction pathway inhibitors. PMID:19755385

  10. Iron Oxide Nanozyme: A Multifunctional Enzyme Mimetic for Biomedical Applications

    PubMed Central

    Gao, Lizeng; Fan, Kelong; Yan, Xiyun

    2017-01-01

    Iron oxide nanoparticles have been widely used in many important fields due to their excellent nanoscale physical properties, such as magnetism/superparamagnetism. They are usually assumed to be biologically inert in biomedical applications. However, iron oxide nanoparticles were recently found to also possess intrinsic enzyme-like activities, and are now regarded as novel enzyme mimetics. A special term, “Nanozyme”, has thus been coined to highlight the intrinsic enzymatic properties of such nanomaterials. Since then, iron oxide nanoparticles have been used as nanozymes to facilitate biomedical applications. In this review, we will introduce the enzymatic features of iron oxide nanozyme (IONzyme), and summarize its novel applications in biomedicine. PMID:28900505

  11. Non-peptidyl insulin mimetics as a potential antidiabetic agent.

    PubMed

    Nankar, Rakesh P; Doble, Mukesh

    2013-08-01

    Insulin has an important role in the maintenance of blood sugar. It is the only available therapeutic agent for the treatment of type 1 diabetes mellitus and there is a dire need for an oral substitute. Different categories of compounds including mono and di substituted benzoquinones, vanadium based compounds and natural products have been reported to cause insulin-like effects either by increasing phosphorylation of insulin receptor (IR) or inhibiting the protein tyrosine phosphatases. This review summarizes the development of various insulin mimetics with special emphasis on their structure-activity relationships and various biological actions they produce.

  12. (Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

    PubMed Central

    Ortega-Caballero, Fernando; Ortiz Mellet, Carmen; García Fernández, José M

    2010-01-01

    Summary Oligosaccharides are currently recognised as having functions that influence the entire spectrum of cell activities. However, a distinct disadvantage of naturally occurring oligosaccharides is their metabolic instability in biological systems. Therefore, much effort has been spent in the past two decades on the development of feasible routes to carbohydrate mimetics which can compete with their O-glycosidic counterparts in cell surface adhesion, inhibit carbohydrate processing enzymes, and interfere in the biosynthesis of specific cell surface carbohydrates. Such oligosaccharide mimetics are potential therapeutic agents against HIV and other infections, against cancer, diabetes and other metabolic diseases. An efficient strategy to access this type of compounds is the replacement of the glycosidic linkage by amide or pseudoamide functions such as thiourea, urea and guanidine. In this review we summarise the advances over the last decade in the synthesis of oligosaccharide mimetics that possess amide and pseudoamide linkages, as well as studies focussing on their supramolecular and recognition properties. PMID:20485602

  13. Distribution and function of TrkB receptors in the developing brain of the opossum Monodelphis domestica.

    PubMed

    Bartkowska, Katarzyna; Aniszewska, Agata; Turlejski, Kris; Djavadian, Ruzanna L

    2014-07-01

    The expression, development pattern, spatiotemporal distribution, and function of TrkB receptors were investigated during the postnatal brain development of the opossum. Full-length TrkB receptor expression was detectable in the newborn opossum, whereas three different short forms that are expressed in the adult brain were almost undetectable in the newborn opossum brain. The highest level of full-length TrkB receptor expression was observed at P35, which corresponds to the time of eye opening. We found that in different brain structures, TrkB receptors were localized in various compartments of cells. The hypothalamus was distinguished by the presence of TrkB receptors not only in cell bodies but also in the neuropil. Double immunofluroscent staining for TrkB and a marker for the identification of the cell phenotype in several brain regions such as the olfactory bulb, hippocampus, thalamus, and cerebellum showed that unlike in eutherians, in the opossum, TrkB receptors were predominantly expressed in neurons. A lack of TrkB receptors in glial cells, particularly astrocytes and oligodendrocytes, provides evidence that TrkB receptors can play a functionally different role in marsupials than in eutherians. The effects of TrkB signaling on the development of cortical progenitor cells were examined in vitro using shRNAs. Blockade of the endogenous TrkB receptor expression induced a decrease in the number of progenitor cells proliferation, whereas the number of apoptotic progenitor cells increased. These changes were statistically significant but relatively small. In contrast, TrkB signaling was strongly involved in regulation of the cortical progenitor cell differentiation process.

  14. Antibody mimetics: promising complementary agents to animal-sourced antibodies.

    PubMed

    Baloch, Abdul Rasheed; Baloch, Abdul Wahid; Sutton, Brian J; Zhang, Xiaoying

    2016-01-01

    Despite their wide use as therapeutic, diagnostic and detection agents, the limitations of polyclonal and monoclonal antibodies have inspired scientists to design the next generation biomedical agents, so-called antibody mimetics that offer many advantages over conventional antibodies. Antibody mimetics can be constructed by protein-directed evolution or fusion of complementarity-determining regions through intervening framework regions. Substantial progress in exploiting human, butterfly (Pieris brassicae) and bacterial systems to design and select mimetics using display technologies has been made in the past 10 years, and one of these mimetics [Kalbitor® (Dyax)] has made its way to market. Many challenges lie ahead to develop mimetics for various biomedical applications, especially those for which conventional antibodies are ineffective, and this review describes the current characteristics, construction and applications of antibody mimetics compared to animal-sourced antibodies. The possible limitations of mimetics and future perspectives are also discussed.

  15. The Naturally Occurring Host Defense Peptide, LL-37, and Its Truncated Mimetics KE-18 and KR-12 Have Selected Biocidal and Antibiofilm Activities Against Candida albicans, Staphylococcus aureus, and Escherichia coli In vitro.

    PubMed

    Luo, Yu; McLean, Denise T F; Linden, Gerard J; McAuley, Danny F; McMullan, Ronan; Lundy, Fionnuala T

    2017-01-01

    Amongst the recognized classes of naturally occurring antimicrobials, human host defense peptides are an important group with an advantage (given their source) that they should be readily translatable to medicinal products. It is also plausible that truncated versions will display some of the biological activities of the parent peptide, with the benefit that they are less costly to synthesize using solid-phase chemistry. The host defense peptide, LL-37, and two truncated mimetics, KE-18 and KR-12, were tested for their inhibitory effects and antibiofilm properties against Candida albicans, Staphylococcus aureus, and Escherichia coli, microorganisms commonly implicated in biofilm-related infections such as ventilator-associated pneumonia (VAP). Using in silico prediction tools, the truncated peptides KE-18 and KR-12 were selected for minimum inhibitory concentration (MIC) and antibiofilm testing on the basis of their favorable cationicity, hydrophobic ratio, and amphipathicity compared with the parent peptide. Two methods were analyzed for determining peptide efficacy against biofilms; a crystal violet assay and an XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] assay. The biocidal activities (measured by MIC) and antibiofilm activities (measured by a crystal violet assay) appeared to be independent. LL-37 had no biocidal action against C. albicans (MIC > 250 μg/ml) but significant effects in both biofilm-prevention and biofilm-inhibition assays. KE-18 and KR-12 yielded superior MIC values against all three microorganisms. Only KE-18 had a significant effect in the biofilm-prevention assay, which persisted even at sub-MICs. Neither of the truncated peptides were active in the biofilm-inhibition assay. KE-18 was shown to bind lipopolysaccharide as effectively as LL-37 and to bind lipoteichoic acid more effectively. None of the peptides showed hemolytic activity against human erythrocytes at the concentrations tested. KE-18 should be

  16. The Naturally Occurring Host Defense Peptide, LL-37, and Its Truncated Mimetics KE-18 and KR-12 Have Selected Biocidal and Antibiofilm Activities Against Candida albicans, Staphylococcus aureus, and Escherichia coli In vitro

    PubMed Central

    Luo, Yu; McLean, Denise T. F.; Linden, Gerard J.; McAuley, Danny F.; McMullan, Ronan; Lundy, Fionnuala T.

    2017-01-01

    Amongst the recognized classes of naturally occurring antimicrobials, human host defense peptides are an important group with an advantage (given their source) that they should be readily translatable to medicinal products. It is also plausible that truncated versions will display some of the biological activities of the parent peptide, with the benefit that they are less costly to synthesize using solid-phase chemistry. The host defense peptide, LL-37, and two truncated mimetics, KE-18 and KR-12, were tested for their inhibitory effects and antibiofilm properties against Candida albicans, Staphylococcus aureus, and Escherichia coli, microorganisms commonly implicated in biofilm-related infections such as ventilator-associated pneumonia (VAP). Using in silico prediction tools, the truncated peptides KE-18 and KR-12 were selected for minimum inhibitory concentration (MIC) and antibiofilm testing on the basis of their favorable cationicity, hydrophobic ratio, and amphipathicity compared with the parent peptide. Two methods were analyzed for determining peptide efficacy against biofilms; a crystal violet assay and an XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] assay. The biocidal activities (measured by MIC) and antibiofilm activities (measured by a crystal violet assay) appeared to be independent. LL-37 had no biocidal action against C. albicans (MIC > 250 μg/ml) but significant effects in both biofilm-prevention and biofilm-inhibition assays. KE-18 and KR-12 yielded superior MIC values against all three microorganisms. Only KE-18 had a significant effect in the biofilm-prevention assay, which persisted even at sub-MICs. Neither of the truncated peptides were active in the biofilm-inhibition assay. KE-18 was shown to bind lipopolysaccharide as effectively as LL-37 and to bind lipoteichoic acid more effectively. None of the peptides showed hemolytic activity against human erythrocytes at the concentrations tested. KE-18 should be

  17. Chemoenzymatic Synthesis of Functional Sialyl LewisX Mimetics with a Heteroaromatic Core

    PubMed Central

    Schlemmer, Claudine; Wiebe, Christine; Ferenc, Dorota; Kowalczyk, Danuta; Wedepohl, Stefanie; Ziegelmüller, Patrick; Dernedde, Jens; Opatz, Till

    2014-01-01

    Functional mimetics of the sialyl LewisX tetrasaccharide were prepared by the enzymatic sialylation of a 1,3-diglycosylated indole and a glycosyl azide, which was subsequently transformed into a 1,4-diglycosylated 1,2,3-triazole, by using the trans-sialidase of Trypanosoma cruzi. These compounds inhibited the binding of E-, L-, and P-selectin-coated nanoparticles to polyacrylamide-bound sialyl-LewisX-containing neighboring sulfated tyrosine residues (sTyr/sLeX-PAA) at low or sub-millimolar concentrations. Except for E-selectin, the mimetics showed higher activities than the natural tetrasaccharide. PMID:24888318

  18. Glycosaminoglycan mimetic peptide nanofibers promote mineralization by osteogenic cells.

    PubMed

    Kocabey, Samet; Ceylan, Hakan; Tekinay, Ayse B; Guler, Mustafa O

    2013-11-01

    Bone tissue regeneration is accomplished by concerted regulation of protein-based extracellular matrix components, glycosaminoglycans (GAGs) and inductive growth factors. GAGs constitute a significant portion of the extracellular matrix and have a significant impact on regulating cellular behavior, either directly or through encapsulation and presentation of growth factors to the cells. In this study we utilized a supramolecular peptide nanofiber system that can emulate both the nanofibrous architecture of collagenous extracellular matrix and the major chemical composition found on GAGs. GAGs and collagen mimetic peptide nanofibers were designed and synthesized with sulfonate and carboxylate groups on the peptide scaffold. The GAG mimetic peptide nanofibers interact with bone morphogenetic protein-2 (BMP-2), which is a critical growth factor for osteogenic activity. The GAG mimicking ability of the peptide nanofibers and their interaction with BMP-2 promoted osteogenic activity and mineralization by osteoblastic cells. Alkaline phosphatase activity, Alizarin red staining and energy dispersive X-ray analysis spectroscopy indicated the efficacy of the peptide nanofibers in inducing mineralization. The multifunctional and bioactive microenvironment presented here provides osteoblastic cells with osteogenic stimuli similar to those observed in native bone tissue. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. Novel thrombopoietin mimetic peptides bind c-Mpl receptor: Synthesis, biological evaluation and molecular modeling.

    PubMed

    Liu, Yaquan; Tian, Fang; Zhi, Dejuan; Wang, Haiqing; Zhao, Chunyan; Li, Hongyu

    2017-02-01

    Thrombopoietin (TPO) acts in promoting the proliferation of hematopoietic stem cells and by initiating specific maturation events in megakaryocytes. Now, TPO-mimetic peptides with amino acid sequences unrelated to TPO are of considerable pharmaceutical interest. In the present paper, four new TPO mimetic peptides that bind and activate c-Mpl receptor have been identified, synthesized and tested by Dual-Luciferase reporter gene assay for biological activities. The molecular modeling research was also approached to understand key molecular mechanisms and structural features responsible for peptide binding with c-Mpl receptor. The results presented that three of four mimetic peptides showed significant activities. In addition, the molecular modeling approaches proved hydrophobic interactions were the driven positive forces for binding behavior between peptides and c-Mpl receptor. TPO peptide residues in P7, P13 and P7' positions were identified by the analysis of hydrogen bonds and energy decompositions as the key ones for benefiting better biological activities. Our data suggested the synthesized peptides have considerable potential for the future development of stable and highly active TPO mimetic peptides.

  20. Substrate-Assisted Inhibition of Ubiquitin-like Protein-Activating Enzymes: The NEDD8 E1 Inhibitor MLN4924 Forms a NEDD8-AMP Mimetic In Situ

    SciTech Connect

    Brownell, James E.; Sintchak, Michael D.; Gavin, James M.; Liao, Hua; Bruzzese, Frank J.; Bump, Nancy J.; Soucy, Teresa A.; Milhollen, Michael A.; Yang, Xiaofeng; Burkhardt, Anne L.; Ma, Jingya; Loke, Huay-Keng; Lingaraj, Trupti; Wu, Dongyun; Hamman, Kristin B.; Spelman, James J.; Cullis, Courtney A.; Langston, Steven P.; Vyskocil, Stepan; Sells, Todd B.; Mallender, William D.; Visiers, Irache; Li, Ping; Claiborne, Christopher F.; Rolfe, Mark; Bolen, Joseph B.; Dick, Lawrence R.

    2010-11-15

    The NEDD8-activating enzyme (NAE) initiates a protein homeostatic pathway essential for cancer cell growth and survival. MLN4924 is a selective inhibitor of NAE currently in clinical trials for the treatment of cancer. Here, we show that MLN4924 is a mechanism-based inhibitor of NAE and creates a covalent NEDD8-MLN4924 adduct catalyzed by the enzyme. The NEDD8-MLN4924 adduct resembles NEDD8 adenylate, the first intermediate in the NAE reaction cycle, but cannot be further utilized in subsequent intraenzyme reactions. The stability of the NEDD8-MLN4924 adduct within the NAE active site blocks enzyme activity, thereby accounting for the potent inhibition of the NEDD8 pathway by MLN4924. Importantly, we have determined that compounds resembling MLN4924 demonstrate the ability to form analogous adducts with other ubiquitin-like proteins (UBLs) catalyzed by their cognate-activating enzymes. These findings reveal insights into the mechanism of E1s and suggest a general strategy for selective inhibition of UBL conjugation pathways.

  1. Substrate-assisted inhibition of ubiquitin-like protein-activating enzymes: the NEDD8 E1 inhibitor MLN4924 forms a NEDD8-AMP mimetic in situ.

    PubMed

    Brownell, James E; Sintchak, Michael D; Gavin, James M; Liao, Hua; Bruzzese, Frank J; Bump, Nancy J; Soucy, Teresa A; Milhollen, Michael A; Yang, Xiaofeng; Burkhardt, Anne L; Ma, Jingya; Loke, Huay-Keng; Lingaraj, Trupti; Wu, Dongyun; Hamman, Kristin B; Spelman, James J; Cullis, Courtney A; Langston, Steven P; Vyskocil, Stepan; Sells, Todd B; Mallender, William D; Visiers, Irache; Li, Ping; Claiborne, Christopher F; Rolfe, Mark; Bolen, Joseph B; Dick, Lawrence R

    2010-01-15

    The NEDD8-activating enzyme (NAE) initiates a protein homeostatic pathway essential for cancer cell growth and survival. MLN4924 is a selective inhibitor of NAE currently in clinical trials for the treatment of cancer. Here, we show that MLN4924 is a mechanism-based inhibitor of NAE and creates a covalent NEDD8-MLN4924 adduct catalyzed by the enzyme. The NEDD8-MLN4924 adduct resembles NEDD8 adenylate, the first intermediate in the NAE reaction cycle, but cannot be further utilized in subsequent intraenzyme reactions. The stability of the NEDD8-MLN4924 adduct within the NAE active site blocks enzyme activity, thereby accounting for the potent inhibition of the NEDD8 pathway by MLN4924. Importantly, we have determined that compounds resembling MLN4924 demonstrate the ability to form analogous adducts with other ubiquitin-like proteins (UBLs) catalyzed by their cognate-activating enzymes. These findings reveal insights into the mechanism of E1s and suggest a general strategy for selective inhibition of UBL conjugation pathways.

  2. BDNF and its TrkB receptor in human fracture healing.

    PubMed

    Kilian, Olaf; Hartmann, Sonja; Dongowski, Nicole; Karnati, Srikanth; Baumgart-Vogt, Eveline; Härtel, Frauke V; Noll, Thomas; Schnettler, Reinhard; Lips, Katrin Susanne

    2014-09-01

    Fracture healing is a physiological process of repair which proceeds in stages, each characterized by a different predominant tissue in the fracture gap. Matrix reorganization is regulated by cytokines and growth factors. Neurotrophins and their receptors might be of importance to osteoblasts and endothelial cells during fracture healing. The aim of this study was to examine the presence of brain-derived neurotrophic factor (BDNF) and its tropomyosin-related kinase B receptor (TrkB) during human fracture healing. BDNF and TrkB were investigated in samples from human fracture gaps and cultured cells using RT-PCR, Western blot, and immunohistochemistry. Endothelial cells and osteoblastic cell lines demonstrated a cytoplasmic staining pattern of BDNF and TrkB in vitro. At the mRNA level, BDNF and TrkB were expressed in the initial and osteoid formation phase of human fracture healing. In the granulation tissue of fracture gap, both proteins--BDNF and TrkB--are concentrated in endothelial and osteoblastic cells at the margins of woven bone suggesting their involvement in the formation of new vessels. There was no evidence of BDNF or TrkB during fracture healing in chondrocytes of human enchondral tissue. Furthermore, BDNF is absent in mature bone. Taken together, BDNF and TrkB are involved in vessel formation and osteogenic processes during human fracture healing. The detection of BDNF and its TrkB receptor during various stages of the bone formation process in human fracture gap tissue were shown for the first time. The current study reveals that both proteins are up-regulated in human osteoblasts and endothelial cells in fracture healing. Copyright © 2014 Elsevier GmbH. All rights reserved.

  3. Max Bergmann lecture protein epitope mimetics in the age of structural vaccinology.

    PubMed

    Robinson, John A

    2013-03-01

    This review highlights the growing importance of protein epitope mimetics in the discovery of new biologically active molecules and their potential applications in drug and vaccine research. The focus is on folded β-hairpin mimetics, which are designed to mimic β-hairpin motifs in biologically important peptides and proteins. An ever-growing number of protein crystal structures reveal how β-hairpin motifs often play key roles in protein-protein and protein-nucleic acid interactions. This review illustrates how using protein structures as a starting point for small-molecule mimetic design can provide novel ligands as protein-protein interaction inhibitors, as protease inhibitors, and as ligands for chemokine receptors and folded RNA targets, as well as novel antibiotics to combat the growing health threat posed by the emergence of antibiotic-resistant bacteria. The β-hairpin antibiotics are shown to target a β-barrel outer membrane protein (LptD) in Pseudomonas sp., which is essential for the biogenesis of the outer cell membrane. Another exciting prospect is that protein epitope mimetics will be of increasing importance in synthetic vaccine design, in the emerging field of structural vaccinology. Crystal structures of protective antibodies bound to their pathogen-derived epitopes provide an ideal starting point for the design of synthetic epitope mimetics. The mimetics can be delivered to the immune system in a highly immunogenic format on the surface of synthetic virus-like particles. The scientific challenges in molecular design remain great, but the potential significance of success in this area is even greater. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.

  4. The design of synthetic superoxide dismutase mimetics: seven-coordinate water soluble manganese(ii) and iron(ii) complexes and their superoxide dismutase-like activity studies.

    PubMed

    Singh, Ovender; Tyagi, Nidhi; Olmstead, Marilyn M; Ghosh, Kaushik

    2017-10-06

    Bio-inspired manganese [Mn(N5Py)(H2O)(CH3OH)](ClO4)2 (1) and iron [Fe(N5Py)(H2O)(ClO4)]ClO4 (2) complexes derived from a pentadentate ligand (N5Py = 2,6-bis((E)-1-phenyl-2-(pyridin-2-ylmethylene)hydrazinyl)pyridine) framework containing a N5 binding motif were synthesized and characterized using different spectroscopic methods. The molecular structures of complexes 1 and 2 were determined by X-ray crystallography. These complexes were found to be stable under physiological conditions and exhibited an excellent superoxide dismutase (SOD) activity. The SOD activity was determined by a xanthine-xanthine oxidase-nitro blue tetrazolium assay and the IC50 values were determined to be 1.53 and 2.09 μM, respectively.

  5. Hierarchical CNFs/MnCo2O4.5 nanofibers as a highly active oxidase mimetic and its application in biosensing.

    PubMed

    Gao, Mu; Lu, Xiaofeng; Nie, Guangdi; Chi, Maoqiang; Wang, Ce

    2017-10-05

    Recently, much attention has been paid on the nanomaterial-based artificial enzymes due to their tunable catalytic activity, high stability and low cost compared to the natural enzymes. Different from the peroxidase mimics which have been studied for several decades, nanomaterials with oxidase-like property are burgeoning in the recent years. In this paper, hierarchical carbon nanofibers (CNFs)/MnCo2O4.5 nanofibers as efficient oxidase mimics are reported. The products are synthesized by an electrospinning technique and an electrochemcial deposition process in which the CNFs are used as the working electrode where MnCo2O4.5 nanosheets deposit on. The resulting binary metal oxide-based nanocomposites exhibit a good oxidase-like activity toward the oxidations of 3,3',5,5'Tetramethylbenzi-dine (TMB), 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) salt and o-Phenylenediamine (OPD) without exogenous addition of H2O2. The system of CNFs/MnCo2O4.5-TMB can be used as a candidate to detect sulfite and ascorbic acid (AA) via a colorimetric method with a high sensitivity. This work provides the efficient utilization and potential applications of binary metal oxide-based nanocomposites with oxidase activities in biosensors and other biotechnologies. © 2017 IOP Publishing Ltd.

  6. Modular protein switches derived from antibody mimetic proteins

    PubMed Central

    Nicholes, N.; Date, A.; Beaujean, P.; Hauk, P.; Kanwar, M.; Ostermeier, M.

    2016-01-01

    Protein switches have potential applications as biosensors and selective protein therapeutics. Protein switches built by fusion of proteins with the prerequisite input and output functions are currently developed using an ad hoc process. A modular switch platform in which existing switches could be readily adapted to respond to any ligand would be advantageous. We investigated the feasibility of a modular protein switch platform based on fusions of the enzyme TEM-1 β-lactamase (BLA) with two different antibody mimetic proteins: designed ankyrin repeat proteins (DARPins) and monobodies. We created libraries of random insertions of the gene encoding BLA into genes encoding a DARPin or a monobody designed to bind maltose-binding protein (MBP). From these libraries, we used a genetic selection system for β-lactamase activity to identify genes that conferred MBP-dependent ampicillin resistance to Escherichia coli. Some of these selected genes encoded switch proteins whose enzymatic activity increased up to 14-fold in the presence of MBP. We next introduced mutations into the antibody mimetic domain of these switches that were known to cause binding to different ligands. To different degrees, introduction of the mutations resulted in switches with the desired specificity, illustrating the potential modularity of these platforms. PMID:26637825

  7. Insulino-mimetic and anti-diabetic effects of zinc.

    PubMed

    Vardatsikos, George; Pandey, Nihar R; Srivastava, Ashok K

    2013-03-01

    While it has long been known that zinc (Zn) is crucial for the proper growth and maintenance of normal biological functions, Zn has also been shown to exert insulin-mimetic and anti-diabetic effects. These insulin-like properties have been demonstrated in isolated cells, tissues, and different animal models of type 1 and type 2 diabetes. Zn treatment has been found to improve carbohydrate and lipid metabolism in rodent models of diabetes. In isolated cells, it enhances glucose transport, glycogen and lipid synthesis, and inhibits gluconeogenesis and lipolysis. The molecular mechanism responsible for the insulin-like effects of Zn compounds involves the activation of several key components of the insulin signaling pathways, which include the extracellular signal-regulated kinase 1/2 (ERK1/2) and phosphatidylinositol 3-kinase (PI3-K)/protein kinase B/Akt (PKB/Akt) pathways. However, the precise molecular mechanisms by which Zn triggers the activation of these pathways remain to be clarified. In this review, we provide a brief history of zinc, and an overview of its insulin-mimetic and anti-diabetic effects, as well as the potential mechanisms by which zinc exerts these effects.

  8. Modular protein switches derived from antibody mimetic proteins.

    PubMed

    Nicholes, N; Date, A; Beaujean, P; Hauk, P; Kanwar, M; Ostermeier, M

    2016-02-01

    Protein switches have potential applications as biosensors and selective protein therapeutics. Protein switches built by fusion of proteins with the prerequisite input and output functions are currently developed using an ad hoc process. A modular switch platform in which existing switches could be readily adapted to respond to any ligand would be advantageous. We investigated the feasibility of a modular protein switch platform based on fusions of the enzyme TEM-1 β-lactamase (BLA) with two different antibody mimetic proteins: designed ankyrin repeat proteins (DARPins) and monobodies. We created libraries of random insertions of the gene encoding BLA into genes encoding a DARPin or a monobody designed to bind maltose-binding protein (MBP). From these libraries, we used a genetic selection system for β-lactamase activity to identify genes that conferred MBP-dependent ampicillin resistance to Escherichia coli. Some of these selected genes encoded switch proteins whose enzymatic activity increased up to 14-fold in the presence of MBP. We next introduced mutations into the antibody mimetic domain of these switches that were known to cause binding to different ligands. To different degrees, introduction of the mutations resulted in switches with the desired specificity, illustrating the potential modularity of these platforms. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  9. Vascular neuroprotection via TrkB- and Akt-dependent cell survival signaling.

    PubMed

    Guo, Shuzhen; Som, Angel T; Waeber, Christian; Lo, Eng H

    2012-11-01

    The cerebral endothelium can be a vital source of signaling factors such as brain-derived neurotrophic factor that defends the neuronal parenchyma against stress and injury. But the underlying mechanisms remain to be fully defined. Here, we use cell models to ask how vascular neuroprotection is sustained. Human brain endothelial cells were grown in culture, and conditioned media were transferred to primary rat cortical neurons. Brain endothelial cell-conditioned media activated neuronal Akt signaling and protected neurons against hypoxia and oxygen-glucose deprivation. Blockade of Akt phosphorylation with the PI3-kinase inhibitor LY294002 negated this vascular neuroprotective effect. Upstream of Akt signaling, the brain-derived neurotrophic factor receptor TrkB (neurotrophic tyrosine kinase receptor, type 2) was involved because depletion with TrkB/Fc eliminated the ability of endothelial-conditioned media to protect neurons against hypoxia. Downstream of Akt signaling, activation of GSK-3β (glycogen synthase kinase 3 beta), caspase 9, caspase 3 and Bad pathways were detected. Taken together, these findings suggest that the molecular basis for vascular neuroprotection involves TrkB-Akt signaling that ameliorates neuronal apoptosis. Further investigation of these mechanisms may reveal new approaches for augmenting endogenous vascular neuroprotection in stroke, brain injury, and neurodegeneration.

  10. Expression of the TrkB neurotrophin receptor by thymic macrophages.

    PubMed Central

    García-Suárez, O; Hannestad, J; Esteban, I; Sainz, R; Naves, F J; Vega, J A

    1998-01-01

    Increasing evidence suggests that some members of the neurotrophic factor family of neurotrophins could be implicated in the regulation of immune responses. Neurotrophins, as well as their tyrosine kinase signal-transducing receptors (the so-called Trk neurotrophin receptors), have been detected in different lymphoid tissues, although their cellular localization is not well known. In this study we used single and double immunohistochemistry to localize TrkB in situ in the rat thymus (in animals from 0 days to 2 years of age), in cytospin preparations of rat thymic cells, and in two mouse monocyte-macrophage cell lines (RAW 264.7 and J774A.1). We found TrkB protein expression in a subpopulation of cells in the corticomedullary junction, which simultaneously expressed the rat macrophage marker ED1. The density of TrkB-expressing cells increased with age, reaching maximal values at 2 years. Conversely, no evidence of TrkB protein expression could be found in dendritic cells, epithelial cells or thymocytes. Thymic macrophages in cytospin preparations, as well as in the mouse monocyte macrophage cell lines, also expressed TrkB protein. Although the possible function of TrkB in the thymic macrophage remains to be clarified, present findings add further evidence to the proposed role of neurotrophins in the immune system. Images Figure 1 Figure 2 Figure 3 Figures 4 and 5 PMID:9741346

  11. TrkB receptor signaling is required for establishment of GABAergic synapses in the cerebellum.

    PubMed

    Rico, Beatriz; Xu, Baoji; Reichardt, Louis F

    2002-03-01

    Neurotrophins are essential to the normal development and maintenance of the nervous system. Neurotrophin signaling is mediated by Trk family tyrosine kinases such as TrkA, TrkB and TrkC, as well as by the pan-neurotrophin receptor p75NTR. Here we have deleted the trkB gene in cerebellar precursors by Wnt1-driven Cre--mediated recombination to study the function of the TrkB in the cerebellum. Despite the absence of TrkB, the mature cerebellum of mutant mice appears similar to that of wild type, with all types of cell present in normal numbers and positions. Granule and Purkinje cell dendrites appear normal and the former have typical numbers of excitatory synapses. By contrast, inhibitory interneurons are strongly affected: although present in normal numbers, they express reduced amounts of GABAergic markers and develop reduced numbers of GABAergic boutons and synaptic specializations. Thus, TrkB is essential to the development of GABAergic neurons and regulates synapse formation in addition to its role in the development of axon terminals.

  12. TrkB receptor signaling is required for establishment of GABAergic synapses in the cerebellum

    PubMed Central

    Rico, Beatriz; Xu, Baoji; Reichardt, Louis F.

    2009-01-01

    Neurotrophins are essential to the normal development and maintenance of the nervous system. Neurotrophin signaling is mediated by Trk family tyrosine kinases such as TrkA, TrkB and TrkC, as well as by the pan-neurotrophin receptor p75NTR. Here we have deleted the trkB gene in cerebellar precursors by Wnt1-driven Cre–mediated recombination to study the function of the TrkB in the cerebellum. Despite the absence of TrkB, the mature cerebellum of mutant mice appears similar to that of wild type, with all types of cell present in normal numbers and positions. Granule and Purkinje cell dendrites appear normal and the former have typical numbers of excitatory synapses. By contrast, inhibitory interneurons are strongly affected: although present in normal numbers, they express reduced amounts of GABAergic markers and develop reduced numbers of GABAergic boutons and synaptic specializations. Thus, TrkB is essential to the development of GABAergic neurons and regulates synapse formation in addition to its role in the development of axon terminals. PMID:11836532

  13. Structure-activity relationships associated with 3,4,5-triphenyl-1H-pyrazole-1-nonanoic acid, a nonprostanoid prostacyclin mimetic.

    PubMed

    Meanwell, N A; Rosenfeld, M J; Wright, J J; Brassard, C L; Buchanan, J O; Federici, M E; Fleming, J S; Seiler, S M

    1992-01-24

    A series of phenylated pyrazoloalkanoic acid derivatives were synthesized and evaluated as inhibitors of ADP-induced human platelet aggregation. 3,4,5-Triphenyl-1H-pyrazole-1-nonanoic acid (8d), with an IC50 of 0.4 microM, was the most potent inhibitor identified in this study. Biochemical studies determined that 8d increased intraplatelet cAMP accumulation and stimulated platelet membrane-bound adenylate cyclase in a concentration-dependent fashion. Displacement of [3H]iloprost by 8d from platelet membranes indicated that the platelet prostacyclin (PGI2) receptor is the locus of biological action. Structure-activity studies demonstrated that the minimum structural requirements for binding to the platelet PGI2 receptor and inhibition of ADP-induced platelet aggregation within this series are a vicinally diphenylated pyrazole substituted with an omega-alkanoic acid side chain eight or nine atoms long. Potency depended upon both side-chain length and its topological relationship with the two phenyl rings.

  14. In situ growth of positively-charged gold nanoparticles on single-walled carbon nanotubes as a highly active peroxidase mimetic and its application in biosensing.

    PubMed

    Zhang, Yuanfu; Xu, Chunli; Li, Baoxin; Li, Yanbin

    2013-05-15

    We prepared a new positively-charged gold nanoparticle ((+)AuNPs)-single-walled carbon nanotubes (SWNTs) nanohybrids. The results showed that small (+)AuNPs dispersed uniformly on the surface of SWNTs. Importantly the resulting nanohybrids exhibited fascinating peroxidase-like activity, which can catalyze oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to develop a blue color in aqueous solution. Furthermore, single-stranded DNA (ss-DNA) can resist salt-induced (+)AuNPs-SWNTs nanohybrids aggregation, whereas double-stranded DNA (ds-DNA) can not inhibit salt-induced nanohybrids aggregation. Based on these unique properties of the (+)AuNPs-SWNTs nanohybrids, we developed a label-free colorimetric method for DNA hybridization detection. The response to target DNA concentration was linear in the range of 0.025-0.5μM with a detection limit of 2nM (3σ). Based on the specific recognition of aptamer, the method can be extended to detect non-nucleic acid targets such as cocaine. The present limit of detection for cocaine is 2nM. The method offers the advantages of simple, cheap, rapid and sensitive. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Alterations of BDNF and trkB mRNA Expression in the 6-Hydroxydopamine-Induced Model of Preclinical Stages of Parkinson’s Disease: An Influence of Chronic Pramipexole in Rats

    PubMed Central

    Berghauzen-Maciejewska, Klemencja; Wardas, Jadwiga; Kosmowska, Barbara; Głowacka, Urszula; Kuter, Katarzyna; Ossowska, Krystyna

    2015-01-01

    Our recent study has indicated that a moderate lesion of the mesostriatal and mesolimbic pathways in rats, modelling preclinical stages of Parkinson’s disease, induces a depressive-like behaviour which is reversed by chronic treatment with pramipexole. The purpose of the present study was to examine the role of brain derived neurotrophic factor (BDNF) signalling in the aforementioned model of depression. Therefore, we investigated the influence of 6-hydoxydopamine (6-OHDA) administration into the ventral region of the caudate-putamen on mRNA levels of BDNF and tropomyosin-related kinase B (trkB) receptor. The BDNF and trkB mRNA levels were determined in the nigrostriatal and limbic structures by in situ hybridization 2 weeks after the operation. Pramipexole (1 mg/kg sc twice a day) and imipramine (10 mg/kg ip once a day) were injected for 2 weeks. The lesion lowered the BDNF and trkB mRNA levels in the hippocampus [CA1, CA3 and dentate gyrus (DG)] and amygdala (basolateral/lateral) as well as the BDNF mRNA content in the habenula (medial/lateral). The lesion did not influence BDNF and trkB expression in the caudate-putamen, substantia nigra, nucleus accumbens (shell and core) and ventral tegmental area (VTA). Chronic imipramine reversed the lesion-induced decreases in BDNF mRNA in the DG. Chronic pramipexole increased BDNF mRNA, but decreased trkB mRNA in the VTA in lesioned rats. Furthermore, it reduced BDNF and trkB mRNA expression in the shell and core of the nucleus accumbens, BDNF mRNA in the amygdala and trkB mRNA in the caudate-putamen in these animals. The present study indicates that both the 6-OHDA-induced dopaminergic lesion and chronic pramipexole influence BDNF signalling in limbic structures, which may be related to their pro-depressive and antidepressant activity in rats, respectively. PMID:25739024

  16. Alterations of BDNF and trkB mRNA expression in the 6-hydroxydopamine-induced model of preclinical stages of Parkinson's disease: an influence of chronic pramipexole in rats.

    PubMed

    Berghauzen-Maciejewska, Klemencja; Wardas, Jadwiga; Kosmowska, Barbara; Głowacka, Urszula; Kuter, Katarzyna; Ossowska, Krystyna

    2015-01-01

    Our recent study has indicated that a moderate lesion of the mesostriatal and mesolimbic pathways in rats, modelling preclinical stages of Parkinson's disease, induces a depressive-like behaviour which is reversed by chronic treatment with pramipexole. The purpose of the present study was to examine the role of brain derived neurotrophic factor (BDNF) signalling in the aforementioned model of depression. Therefore, we investigated the influence of 6-hydoxydopamine (6-OHDA) administration into the ventral region of the caudate-putamen on mRNA levels of BDNF and tropomyosin-related kinase B (trkB) receptor. The BDNF and trkB mRNA levels were determined in the nigrostriatal and limbic structures by in situ hybridization 2 weeks after the operation. Pramipexole (1 mg/kg sc twice a day) and imipramine (10 mg/kg ip once a day) were injected for 2 weeks. The lesion lowered the BDNF and trkB mRNA levels in the hippocampus [CA1, CA3 and dentate gyrus (DG)] and amygdala (basolateral/lateral) as well as the BDNF mRNA content in the habenula (medial/lateral). The lesion did not influence BDNF and trkB expression in the caudate-putamen, substantia nigra, nucleus accumbens (shell and core) and ventral tegmental area (VTA). Chronic imipramine reversed the lesion-induced decreases in BDNF mRNA in the DG. Chronic pramipexole increased BDNF mRNA, but decreased trkB mRNA in the VTA in lesioned rats. Furthermore, it reduced BDNF and trkB mRNA expression in the shell and core of the nucleus accumbens, BDNF mRNA in the amygdala and trkB mRNA in the caudate-putamen in these animals. The present study indicates that both the 6-OHDA-induced dopaminergic lesion and chronic pramipexole influence BDNF signalling in limbic structures, which may be related to their pro-depressive and antidepressant activity in rats, respectively.

  17. Chronic Wound Dressings Based on Collagen-Mimetic Proteins

    PubMed Central

    Cereceres, Stacy; Touchet, Tyler; Browning, Mary Beth; Smith, Clayton; Rivera, Jose; Höök, Magnus; Whitfield-Cargile, Canaan; Russell, Brooke; Cosgriff-Hernandez, Elizabeth

    2015-01-01

    Objective: Chronic wounds are projected to reach epidemic proportions due to the aging population and the increasing incidence of diabetes. There is a strong clinical need for an improved wound dressing that can balance wound moisture, promote cell migration and proliferation, and degrade at an appropriate rate to minimize the need for dressing changes. Approach: To this end, we have developed a bioactive, hydrogel microsphere wound dressing that incorporates a collagen-mimetic protein, Scl2GFPGER, to promote active wound healing. A redesigned Scl2GFPGER, engineered collagen (eColGFPGER), was created to reduce steric hindrance of integrin-binding motifs and increase overall stability of the triple helical backbone, thereby resulting in increased cell adhesion to substrates. Results: This study demonstrates the successful modification of the Scl2GFPGER protein to eColGFPGER, which displayed enhanced stability and integrin interactions. Fabrication of hydrogel microspheres provided a matrix with adaptive moisture technology, and degradation rates have potential for use in human wounds. Innovation: This collagen-mimetic wound dressing was designed to permit controlled modulation of cellular interactions and degradation rate without impact on other physical properties. Its fabrication into uniform hydrogel microspheres provides a bioactive dressing that can readily conform to irregular wounds. Conclusion: Overall, this new eColGFPGER shows strong promise in the generation of bioactive hydrogels for wound healing as well as a variety of tissue scaffolds. PMID:26244101

  18. Genetic analysis of the TrkB gene and schizophrenia in the Japanese population: Juntendo University Schizophrenia Projects (JUSP).

    PubMed

    Higashi, Maiko; Higashi, Shinji; Ohnuma, Tohru; Shibata, Nobuto; Sakai, Yoshie; Arai, Heii

    2007-09-20

    The presence of cognitive and social impairments during childhood and adolescence in patients with schizophrenia has lead to the widespread hypothesis that schizophrenia may be a neurodevelopmental disorder, which suggests that risk genes for schizophrenia may act through the disruption of normal neurodevelopmental processes. Moreover, recent studies indicate that TrkB, which is receptor of neurotrophins including BDNF, might be involved in schizophrenia. The aim of this study is to evaluate the role of sequence variation at the TrkB locus on schizophrenia. We genotyped 12 single nucleotide polymorphisms (SNPs) across TrkB in 276 subjects with schizophrenia and 274 control subjects from the Japanese population and assessed whether TrkB SNPs are associated with a diagnosis of schizophrenia. In addition, we also investigated if any association exists between the TrkB SNPs and the premorbid functioning as measured by M-PAS using 62 subjects with schizophrenia. The TrkB SNPs were not significantly associated with a diagnosis of schizophrenia. Although one TrkB SNP (rs920776) showed weak association with premorbid functioning (p=0.025), the significance did not remain after Bonferroni correction. Thus, these results do not support a significant role for TrkB sequence variation in the etiology of schizophrenia.

  19. TrkB and PKMζ regulate synaptic localization of PSD-95 in developing cortex

    PubMed Central

    Yoshii, Akira; Murata, Yasunobu; Kim, Jihye; Zhang, Chao; Shokat, Kevan M.; Constantine-Paton, Martha

    2011-01-01

    Post-synaptic density 95 (PSD-95), the major scaffold at excitatory synapses, is critical for synapse maturation and learning. In rodents, eye opening, the onset of pattern vision, triggers a rapid movement of PSD-95 from visual neuron somata to synapses. We previously showed that the PI3 kinase-Akt pathway downstream of BDNF/TrkB signaling stimulates synaptic delivery of PSD-95 via vesicular transport. However, vesicular transport requires PSD-95 palmitoylation to attach it to a lipid membrane. Also PSD-95 insertion at synapses is known to require this lipid modification. Here, we show that BDNF/TrkB signaling is also necessary for PSD-95 palmitoylation and its transport to synapses in mouse visual cortical layer 2/3 neurons. However, palmitoylation of PSD-95 requires the activation of another pathway downstream of BDNF/TrkB, namely signaling through PLCγ and the brain-specific PKC variant PKMζ. We find that PKMζ selectively regulates phosphorylation of the palmitoylation enzyme ZDHHC8. Inhibition of PKMζ results in a reduction of synaptic PSD-95 accumulation in vivo, which can be rescued by over-expression ZDHHC8. Therefore, TrkB and PKMζ, two critical regulators of synaptic plasticity, facilitate PSD-95 targeting to synapses. These results also indicate that palmitoylation can be regulated by a trophic factor. Our findings have implications for neurodevelopmental disorders as well as ageing brains. PMID:21849550

  20. TrkB and protein kinase Mζ regulate synaptic localization of PSD-95 in developing cortex.

    PubMed

    Yoshii, Akira; Murata, Yasunobu; Kim, Jihye; Zhang, Chao; Shokat, Kevan M; Constantine-Paton, Martha

    2011-08-17

    Postsynaptic density 95 (PSD-95), the major scaffold at excitatory synapses, is critical for synapse maturation and learning. In rodents, eye opening, the onset of pattern vision, triggers a rapid movement of PSD-95 from visual neuron somata to synapses. We showed previously that the PI3 kinase-Akt pathway downstream of BDNF/TrkB signaling stimulates synaptic delivery of PSD-95 via vesicular transport. However, vesicular transport requires PSD-95 palmitoylation to attach it to a lipid membrane. Also, PSD-95 insertion at synapses is known to require this lipid modification. Here, we show that BDNF/TrkB signaling is also necessary for PSD-95 palmitoylation and its transport to synapses in mouse visual cortical layer 2/3 neurons. However, palmitoylation of PSD-95 requires the activation of another pathway downstream of BDNF/TrkB, namely, signaling through phospholipase Cγ and the brain-specific PKC variant protein kinase M ζ (PKMζ). We find that PKMζ selectively regulates phosphorylation of the palmitoylation enzyme ZDHHC8. Inhibition of PKMζ results in a reduction of synaptic PSD-95 accumulation in vivo, which can be rescued by overexpressing ZDHHC8. Therefore, TrkB and PKMζ, two critical regulators of synaptic plasticity, facilitate PSD-95 targeting to synapses. These results also indicate that palmitoylation can be regulated by a trophic factor. Our findings have implications for neurodevelopmental disorders as well as aging brains.

  1. Non-local F(R)-mimetic gravity

    NASA Astrophysics Data System (ADS)

    Myrzakulov, Ratbay; Sebastiani, Lorenzo

    2016-06-01

    In this paper, we study non-local F(R)-mimetic gravity. We implement mimetic gravity in the framework of non-local F(R)-theories of gravity. Given some specific class of models and using a potential on the mimetic field, we investigate some scenarios related to the early-time universe, namely the inflation and the cosmological bounce, which bring to Einstein's gravity with cold dark matter at the late-time.

  2. NEC violation in mimetic cosmology revisited

    NASA Astrophysics Data System (ADS)

    Ijjas, Anna; Ripley, Justin; Steinhardt, Paul J.

    2016-09-01

    In the context of Einstein gravity, if the null energy condition (NEC) is satisfied, the energy density in expanding space-times always decreases while in contracting space-times the energy density grows and the universe eventually collapses into a singularity. In particular, no non-singular bounce is possible. It is, though, an open question if this energy condition can be violated in a controlled way, i.e., without introducing pathologies, such as unstable negative-energy states or an imaginary speed of sound. In this letter, we will re-examine the claim that the recently proposed mimetic scenario can violate the NEC without pathologies. We show that mimetic cosmology is prone to gradient instabilities even in cases when the NEC is satisfied (except for trivial examples). Most interestingly, the source of the instability is always the Einstein-Hilbert term in the action. The matter stress-energy component does not contribute spatial gradient terms but instead makes the problematic curvature modes dynamical. We also show that mimetic cosmology can be understood as a singular limit of known, well-behaved theories involving higher-derivative kinetic terms and discuss ways of removing the instability.

  3. Designing a small molecule erythropoietin mimetic.

    PubMed

    Guarnieri, Frank

    2015-01-01

    Erythropoietin (EPO) is a protein made by the kidneys in response to low red blood cell count that is secreted into the bloodstream and binds to a receptor on hematopoietic stem cells in the bone marrow inducing them to become new red blood cells. EPO made with recombinant DNA technology was brought to market in the 1980s to treat anemia caused by kidney disease and cancer chemotherapy. Because EPO infusion was able to replace blood transfusions in many cases, it rapidly became a multibillion dollar per year drug and as the first biologic created with recombinant technology it launched the biotech industry. For many years intense research was focused on creating a small molecule orally available EPO mimetic. The Robert Wood Johnson (RWJ) group seemed to definitively establish that only large peptides with a minimum of 60 residues could replace EPO, as anything less was not a full agonist. An intense study of the published work led me to hypothesize that the size of the mimetic is not the real issue, but the symmetry making and breaking of the EPO receptor induced by the ligand is the key to activating the stem cells. This analysis meant that residues in the binding site of the receptor deemed absolutely essential for ligand binding and activation from mutagenesis experiments, were probably not really that important. My fundamental hypotheses were: (a) the symmetric state of the homodimeric receptor is the most stable state and thus must be the off-state, (b) a highly localized binding site exists at a pivot point where the two halves of the receptor meet, (c) small molecules can be created that have high potency for this site that will be competitive with EPO and thus can displace the protein-protein interaction, (d) small symmetric molecules will stabilize the symmetric off-state of the receptor, and (e) a key asymmetry in the small molecule will stabilize a mirror image asymmetry in the receptor resulting in the stabilization of the on-state and proliferation of

  4. Progress of Mimetic Enzymes and Their Applications in Chemical Sensors.

    PubMed

    Yang, Bin; Li, Jianping; Deng, Huan; Zhang, Lianming

    2016-11-01

    The need to develop innovative and reformative approaches to synthesize chemical sensors has increased in recent years because of demands for selectivity, stability, and reproducibility. Mimetic enzymes provide an efficient and convenient method for chemical sensors. This review summarizes the application of mimetic enzymes in chemical sensors. Mimetic enzymes can be classified into five categories: hydrolases, oxidoreductases, transferases, isomerases, and induced enzymes. Potential and recent applications of mimetic enzymes in chemical sensors are reviewed in detail, and the outlook of profound development has been illustrated.

  5. Transglutaminase 2 overexpression induces depressive-like behavior and impaired TrkB signaling in mice

    PubMed Central

    Pandya, Chirayu D; Hoda, Nasrul; Crider, Amanda; Peter, Diya; Kutiyanawalla, Ammar; Kumar, Sanjiv; Ahmed, Anthony O; Turecki, Gustavo; Hernandez, Caterina M; Terry, Alvin V

    2016-01-01

    Serotonin (5-HT) and brain derived neurotrophic factor (BDNF) are two signaling molecules that play important regulatory roles in the development and plasticity of neural circuits that are known to be altered in depression. However, the mechanism by which 5-HT regulates BDNF signaling is unknown. In the present study, we found that 5-HT treatment increases BDNF receptor, TrkB (tropomyosin related kinase B) levels in mouse primary cortical neurons via a Rac1 (RAS-related C3 botulinum toxin substrate 1)-dependent mechanism. Significant increases in the levels of transglutaminase 2 (TG2, which is implicated in transamidation of 5-HT to Rac1) are observed in the mouse prefrontal cortex (PFC) following chronic exposure to stress. We also found that TG2 levels are increased in the postmortem PFC of depressed suicide subjects relative to matched controls. Moreover, in mice, neuronal overexpression of TG2 resulted in the atrophy of neurons and reduced levels of TrkB in the PFC as well as a depressive-like phenotype. Overexpression of TG2 in mouse cortical neurons reduced TrkB levels as a result of impaired endocytosis of TrkB. TG2 inhibition by either a viral particle or pharmacological approach attenuated behavioral deficits caused by chronic unpredictable stress. Moreover, the overexpression of TrkB in the mouse PFC ameliorated the depressive-like phenotype of TG2 overexpressed mice. Taken together, these postmortem and preclinical findings identify TG2 as a critical mediator of the altered TrkB expression and depressive-like behaviors associated with chronic exposure to stress and suggest that TG2 may represent a novel therapeutic target in depression. PMID:27620841

  6. Expression and cell localization of brain-derived neurotrophic factor and TrkB during zebrafish retinal development.

    PubMed

    Germanà, A; Sánchez-Ramos, C; Guerrera, M C; Calavia, M G; Navarro, M; Zichichi, R; García-Suárez, O; Pérez-Piñera, P; Vega, Jose A

    2010-09-01

    Brain-derived neurotrophic factor (BDNF) signaling through TrkB regulates different aspects of neuronal development, including survival, axonal and dendritic growth, and synapse formation. Despite recent advances in our understanding of the functional significance of BDNF and TrkB in the retina, the cell types in the retina that express BDNF and TrkB, and the variations in their levels of expression during development, remain poorly defined. The goal of the present study is to determine the age-dependent changes in the levels of expression and localization of BDNF and TrkB in the zebrafish retina. Zebrafish retinas from 10 days post-fertilization (dpf) to 180 dpf were used to perform PCR, Western blot and immunohistochemistry. Both BDNF and TrkB mRNAs, and BDNF and full-length TrkB proteins were detected at all ages sampled. The localization of these proteins in the retina was very similar at all time points studied. BDNF immunoreactivity was found in the outer nuclear layer, the outer plexiform layer and the inner plexiform layer, whereas TrkB immunoreactivity was observed in the inner plexiform layer and, to a lesser extent, in the ganglion cell layer. These results demonstrate that the pattern of expression of BDNF and TrkB in the retina of zebrafish remains unchanged during postembryonic development and adult life. Because TrkB expression in retina did not change with age, cells expressing TrkB may potentially be able to respond during the entire lifespan of zebrafish to BDNF either exogenously administered or endogenously produced, acting through paracrine mechanisms.

  7. Expression and cell localization of brain-derived neurotrophic factor and TrkB during zebrafish retinal development

    PubMed Central

    Germanà, A; Sánchez-Ramos, C; Guerrera, M C; Calavia, M G; Navarro, M; Zichichi, R; García-Suárez, O; Pérez-Piñera, P; Vega, Jose A

    2010-01-01

    Brain-derived neurotrophic factor (BDNF) signaling through TrkB regulates different aspects of neuronal development, including survival, axonal and dendritic growth, and synapse formation. Despite recent advances in our understanding of the functional significance of BDNF and TrkB in the retina, the cell types in the retina that express BDNF and TrkB, and the variations in their levels of expression during development, remain poorly defined. The goal of the present study is to determine the age-dependent changes in the levels of expression and localization of BDNF and TrkB in the zebrafish retina. Zebrafish retinas from 10 days post-fertilization (dpf) to 180 dpf were used to perform PCR, Western blot and immunohistochemistry. Both BDNF and TrkB mRNAs, and BDNF and full-length TrkB proteins were detected at all ages sampled. The localization of these proteins in the retina was very similar at all time points studied. BDNF immunoreactivity was found in the outer nuclear layer, the outer plexiform layer and the inner plexiform layer, whereas TrkB immunoreactivity was observed in the inner plexiform layer and, to a lesser extent, in the ganglion cell layer. These results demonstrate that the pattern of expression of BDNF and TrkB in the retina of zebrafish remains unchanged during postembryonic development and adult life. Because TrkB expression in retina did not change with age, cells expressing TrkB may potentially be able to respond during the entire lifespan of zebrafish to BDNF either exogenously administered or endogenously produced, acting through paracrine mechanisms. PMID:20649707

  8. A BDNF loop-domain mimetic acutely reverses spontaneous apneas and respiratory abnormalities during behavioral arousal in a mouse model of Rett syndrome

    PubMed Central

    Kron, Miriam; Lang, Min; Adams, Ian T.; Sceniak, Michael; Longo, Frank; Katz, David M.

    2014-01-01

    Reduced levels of brain-derived neurotrophic factor (BDNF) are thought to contribute to the pathophysiology of Rett syndrome (RTT), a severe neurodevelopmental disorder caused by loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). In Mecp2 mutant mice, BDNF deficits have been associated with breathing abnormalities, a core feature of RTT, as well as with synaptic hyperexcitability within the brainstem respiratory network. Application of BDNF can reverse hyperexcitability in acute brainstem slices from Mecp2-null mice, suggesting that therapies targeting BDNF or its receptor, TrkB, could be effective at acute reversal of respiratory abnormalities in RTT. Therefore, we examined the ability of LM22A-4, a small-molecule BDNF loop-domain mimetic and TrkB partial agonist, to modulate synaptic excitability within respiratory cell groups in the brainstem nucleus tractus solitarius (nTS) and to acutely reverse abnormalities in breathing at rest and during behavioral arousal in Mecp2 mutants. Patch-clamp recordings in Mecp2-null brainstem slices demonstrated that LM22A-4 decreases excitability at primary afferent synapses in the nTS by reducing the amplitude of evoked excitatory postsynaptic currents and the frequency of spontaneous and miniature excitatory postsynaptic currents. In vivo, acute treatment of Mecp2-null and -heterozygous mutants with LM22A-4 completely eliminated spontaneous apneas in resting animals, without sedation. Moreover, we demonstrate that respiratory dysregulation during behavioral arousal, a feature of human RTT, is also reversed in Mecp2 mutants by acute treatment with LM22A-4. Together, these data support the hypothesis that reduced BDNF signaling and respiratory dysfunction in RTT are linked, and establish the proof-of-concept that treatment with a small-molecule structural mimetic of a BDNF loop domain and a TrkB partial agonist can acutely reverse abnormal breathing at rest and in response to behavioral arousal

  9. The first MCL-1-selective BH3 mimetics have therapeutic potential for chronic lymphocytic leukemia.

    PubMed

    Besbes, Samaher; Pocard, Marc; Mirshahi, Massoud; Billard, Christian

    2016-04-01

    Small-molecule BH3 mimetics are designed to mimic the BH3 domain of BH3-only BCL-2 family members which are antagonists of the prosurvival members (such as BCL-2, BCL-XL and MCL-1). The BH3 mimetics are intended to bind with high affinity to prosurvival proteins, in order to inhibit their functional activity and hence to induce apoptosis in cancer cells. Both navitoclax (BCL-2/BCL-XL antagonist) and ABT-199/venetoclax (BCL-2-selective inhibitor) have demonstrated therapeutic efficacy especially in chronic lymphocytic leukemia (CLL). However, these BH3 mimetics cannot antagonize the prosurvival protein MCL-1 that is overexpressed and involved in therapeutic resistance in CLL. Furthermore, until now, none of the reported small-molecule MCL-1 inhibitors bound to their target with high affinity. The first MCL-1-selective BH3 mimetics capable of high-affinity binding and inducing apoptosis in cancer cells through an on-target mechanism have just been identified. This discovery should advance the translational research to implement novel drugs in treating CLL.

  10. New diketone based vanadium complexes as insulin mimetics.

    PubMed

    Sheela, A; Roopan, S Mohana; Vijayaraghavan, R

    2008-10-01

    Since 1985, when Heyliger et al. first reported the in vivo insulin mimetic activity of oral vanadate, extensive studies exploring vanadium chemistry, including the synthesis of novel complexes and their biological effects both in vitro and in vivo have been pursued. Such complexes have emerged as possible potential agents for diabetes therapy. Among the several existing compounds, diketone based vanadium complexes have been chosen for the current study. Two new complexes namely bisdimethylmalonatooxovanadium(IV) and bisdiethylmalonatooxovanadium(IV) have been synthesized and characterized by UV-visible, FTIR and mass spectral studies. The antidiabetic activity of the complexes was proved by animal study. The results show that the above complexes have comparable antidiabetic potential with respect to the standard drug as well as with bisacetylacetonatooxovanadium(IV) which has been studied earlier by Reul et al.

  11. The Role of Brain-Derived Neurotrophic Factor Receptors in the Mature Hippocampus: Modulation of Long-Term Potentiation through a Presynaptic Mechanism involving TrkB

    PubMed Central

    Xu, Baoji; Gottschalk, Wolfram; Chow, Ana; Wilson, Rachel I.; Schnell, Eric; Zang, Keling; Wang, Denan; Nicoll, Roger A.; Lu, Bai; Reichardt, Louis F.

    2009-01-01

    The neurotrophin BDNF has been shown to modulate long-term potentiation (LTP) at Schaffer collateral-CA1 hippocampal synapses. Mutants in the BDNF receptor gene trkB and antibodies to its second receptor p75NTR have been used to determine the receptors and cells involved in this response. Inhibition of p75NTR does not detectably reduce LTP or affect presynaptic function, but analyses of newly generated trkB mutants implicate TrkB. One mutant has reduced expression in a normal pattern of TrkB throughout the brain. The second mutant was created by cre-loxP-mediated removal of TrkB in CA1 pyramidal neurons of this mouse. Neither mutant detectably impacts survival or morphology of hippocampal neurons. TrkB reduction, however, affects presynaptic function and reduces the ability of tetanic stimulation to induce LTP. Postsynaptic glutamate receptors are not affected by TrkB reduction, indicating that BDNF does not modulate plasticity through postsynaptic TrkB. Consistent with this, elimination of TrkB in postsynaptic neurons does not affect LTP. Moreover, normal LTP is generated in the mutant with reduced TrkB by a depolarization–low-frequency stimulation pairing protocol that puts minimal demands on presynaptic terminal function. Thus, BDNF appears to act through TrkB presynaptically, but not postsynaptically, to modulate LTP. PMID:10995833

  12. From neutron stars to quark stars in mimetic gravity

    NASA Astrophysics Data System (ADS)

    Astashenok, Artyom V.; Odintsov, Sergei D.

    2016-09-01

    Realistic models of neutron and quark stars in the framework of mimetic gravity with a Lagrange multiplier constraint are presented. We discuss the effect of a mimetic scalar aiming to describe dark matter on the mass-radius relation and the moment of inertia for slowly rotating relativistic stars. The mass-radius relation and moment of inertia depend on the value of the mimetic scalar in the center of the star. This fact leads to the ambiguity in the mass-radius relation for a given equation of state. Such ambiguity allows us to explain some observational facts better than in standard general relativity. The case of mimetic potential V (ϕ )˜A eC ϕ2 is considered in detail. The relative deviation of the maximal moment of inertia is approximately twice as large as the relative deviation of the maximal stellar mass. We also briefly discuss the mimetic f (R ) gravity. In the case of f (R )=R +a R2 mimetic gravity, it is expected that the increase of maximal mass and maximal moment of inertia due to the mimetic scalar becomes much stronger with bigger parameter a . The influence of the scalar field in mimetic gravity can lead to the possible existence of extreme neutron stars with large masses.

  13. Disformal transformations, veiled General Relativity and Mimetic Gravity

    SciTech Connect

    Deruelle, Nathalie; Rua, Josephine E-mail: rua@cbpf.br

    2014-09-01

    In this Note we show that Einstein's equations for gravity are generically invariant under ''disformations''. We also show that the particular subclass when this is not true yields the equations of motion of ''Mimetic Gravity''. Finally we give the ''mimetic'' generalization of the Schwarzschild solution.

  14. Social variables exert selective pressures in the evolution and form of primate mimetic musculature.

    PubMed

    Burrows, Anne M; Li, Ly; Waller, Bridget M; Micheletta, Jerome

    2016-04-01

    Mammals use their faces in social interactions more so than any other vertebrates. Primates are an extreme among most mammals in their complex, direct, lifelong social interactions and their frequent use of facial displays is a means of proximate visual communication with conspecifics. The available repertoire of facial displays is primarily controlled by mimetic musculature, the muscles that move the face. The form of these muscles is, in turn, limited by and influenced by phylogenetic inertia but here we use examples, both morphological and physiological, to illustrate the influence that social variables may exert on the evolution and form of mimetic musculature among primates. Ecomorphology is concerned with the adaptive responses of morphology to various ecological variables such as diet, foliage density, predation pressures, and time of day activity. We present evidence that social variables also exert selective pressures on morphology, specifically using mimetic muscles among primates as an example. Social variables include group size, dominance 'style', and mating systems. We present two case studies to illustrate the potential influence of social behavior on adaptive morphology of mimetic musculature in primates: (1) gross morphology of the mimetic muscles around the external ear in closely related species of macaque (Macaca mulatta and Macaca nigra) characterized by varying dominance styles and (2) comparative physiology of the orbicularis oris muscle among select ape species. This muscle is used in both facial displays/expressions and in vocalizations/human speech. We present qualitative observations of myosin fiber-type distribution in this muscle of siamang (Symphalangus syndactylus), chimpanzee (Pan troglodytes), and human to demonstrate the potential influence of visual and auditory communication on muscle physiology. In sum, ecomorphologists should be aware of social selective pressures as well as ecological ones, and that observed morphology might

  15. Acid-sensing ion channel 2 (asic 2) and trkb interrelationships within the intervertebral disc

    PubMed Central

    Cuesta, Antonio; Viña, Eliseo; Cabo, Roberto; Vázquez, Gorka; Cobo, Ramón; García-Suárez, Olivia; García-Cosamalón, José; Vega, José A

    2015-01-01

    The cells of the intervertebral disc (IVD) have an unusual acidic and hyperosmotic microenvironment. They express acid-sensing ion channels (ASICs), gated by extracellular protons and mechanical forces, as well as neurotrophins and their signalling receptors. In the nervous tissues some neurotrophins regulate the expression of ASICs. The expression of ASIC2 and TrkB in human normal and degenerated IVD was assessed using quantitative-PCR, Western blot, and immunohistochemistry. Moreover, we investigated immunohistochemically the expression of ASIC2 in the IVD of TrkB-deficient mice. ASIC2 and TrkB mRNAs were found in normal human IVD and both increased significantly in degenerated IVD. ASIC2 and TrkB proteins were also found co-localized in a variable percentage of cells, being significantly higher in degenerated IVD than in controls. The murine IVD displayed ASIC2 immunoreactivity which was absent in the IVD of TrkB-deficient mice. Present results demonstrate the occurrence of ASIC2 and TrkB in the human IVD, and the increased expression of both in pathological IVD suggest their involvement in IVD degeneration. These data also suggest that TrkB-ligands might be involved in the regulation of ASIC2 expression, and therefore in mechanisms by which the IVD cells accommodate to low pH and hypertonicity. PMID:26617738

  16. Role of TrkB expression in rat adrenal gland during acute immobilization stress

    PubMed Central

    Kondo, Yusuke; To, Masahiro; Saruta, Juri; Hayashi, Takashi; Sugiyama, Hiroki; Tsukinoki, Keiichi

    2013-01-01

    Expression of tyrosine receptor kinase B (TrkB), a receptor for brain-derived neurotrophic factor (BDNF), is markedly elevated in the adrenal medulla during immobilization stress. Catecholamine release was confirmed in vitro by stimulating chromaffin cells with recombinant BDNF. We investigated the role of TrkB and the localization of BDNF in the adrenal gland during immobilization stress for 60 min. Blood catecholamine levels increased after stimulation with TrkB expressed in the adrenal medulla during 60-min stress; however, blood catecholamine levels did not increase in adrenalectomized rats. Furthermore, expression of BDNF mRNA and protein was detected in the adrenal medulla during 60-min stress. Similarly, in rats undergoing sympathetic nerve block with propranolol, BDNF mRNA and protein were detected in the adrenal medulla during 60-min stress. These results suggest that signal transduction of TrkB in the adrenal medulla evokes catecholamine release. In addition, catecholamine release was evoked by both the hypothalamic–pituitary–adrenal axis and autocrine signaling by BDNF in the adrenal gland. BDNF–TrkB interaction may play a role in a positive feedback loop in the adrenal medulla during immobilization stress. PMID:23017014

  17. Mimetic gain in batesian and Müllerian mimicry.

    PubMed

    Hadeler, K P; de Mottoni, P; Tesei, A

    1982-04-01

    Starting from field investigations and experiments on mimetic butterfly populations a model for two mimetic species is developed. The model comprises various features such as the growth rates and carrying capacities of the two species, their unpalatability to predators, the recruitment and the training of the predators and, most important, the similarity of the two mimetic species. The model ranges from pure Batesian to pure Müllerian mimicry over a spectrum of possible cases. The mimetic gain is introduced as the relative increase in equilibrium density in a mimetic situation as compared to a situation where mimicry is not present. The dependence of this quantity on parameters as growth rate, carrying capacity, unpalatability, and similarity is investigated using numerical methods.

  18. Inflamed leukocyte-mimetic nanoparticles for molecular imaging of inflammation.

    PubMed

    Chen, Xiaoyue; Wong, Richard; Khalidov, Ildar; Wang, Andrew Y; Leelawattanachai, Jeerapond; Wang, Yi; Jin, Moonsoo M

    2011-10-01

    Dysregulated host inflammatory response causes many diseases, including cardiovascular and neurodegenerative diseases, cancer, and sepsis. Sensitive detection of the site of inflammation will, therefore, produce a wide-ranging impact on disease diagnosis and treatment. We hypothesized that nanoprobes designed to mimic the molecular interactions occurring between inflamed leukocytes and endothelium may possess selectivity toward diverse host inflammatory responses. To incorporate inflammation-sensitive molecular interactions, super paramagnetic iron oxide nanoparticles were conjugated with integrin lymphocyte function-associated antigen (LFA)-1 I domain, engineered to mimic activated leukocytes in physiology. Whole body optical and magnetic resonance imaging in vivo revealed that leukocyte-mimetic nanoparticles localized preferentially to the vasculature within and in the invasive front of the tumor, as well as to the site of acute inflammation. This study explored in vivo detection of tumor-associated vasculature with systemically injected inflammation-specific nanoparticles, presenting a possibility of tumor detection by inflamed tumor microenvironment.

  19. Towards protein-based viral mimetics for cancer therapies.

    PubMed

    Unzueta, Ugutz; Céspedes, María Virtudes; Vázquez, Esther; Ferrer-Miralles, Neus; Mangues, Ramón; Villaverde, Antonio

    2015-05-01

    High resistance and recurrence rates, together with elevated drug clearance, compel the use of maximum-tolerated drug doses in cancer therapy, resulting in high-grade toxicities and limited clinical applicability. Promoting active drug accumulation in tumor tissues would minimize such issues and improve therapeutic outcomes. A new class of therapeutic drugs suitable for the task has emerged based on the concept of virus-mimetic nanocarriers, or 'artificial viruses'. Among the spectrum of materials under exploration in nanocarrier research, proteins offer unparalleled structural and functional versatility for designing virus-like molecular vehicles. By exhibiting 'smart' functions and biomimetic traits, protein-based nanocarriers will be a step ahead of the conventional drug-protein conjugates already in the clinic in ensuring efficient delivery of passenger antitumor drugs.

  20. Exercise Mimetics: Impact on Health and Performance.

    PubMed

    Fan, Weiwei; Evans, Ronald M

    2017-02-07

    The global epidemic of obesity and its associated chronic diseases is largely attributed to an imbalance between caloric intake and energy expenditure. While physical exercise remains the best solution, the development of muscle-targeted "exercise mimetics" may soon provide a pharmaceutical alternative to battle an increasingly sedentary lifestyle. At the same time, these advances are fueling a raging debate on their escalating use as performance-enhancing drugs in high-profile competitions such as the Olympics. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. A loss-of-function screen for phosphatases that regulate neurite outgrowth identifies PTPN12 as a negative regulator of TrkB tyrosine phosphorylation.

    PubMed

    Ambjørn, Malene; Dubreuil, Véronique; Miozzo, Federico; Nigon, Fabienne; Møller, Bente; Issazadeh-Navikas, Shohreh; Berg, Jacob; Lees, Michael; Sap, Jan

    2013-01-01

    Alterations in function of the neurotrophin BDNF are associated with neurodegeneration, cognitive decline, and psychiatric disorders. BDNF promotes axonal outgrowth and branching, regulates dendritic tree morphology and is important for axonal regeneration after injury, responses that largely result from activation of its tyrosine kinase receptor TrkB. Although intracellular neurotrophin (NT) signaling presumably reflects the combined action of kinases and phosphatases, little is known about the contributions of the latter to TrkB regulation. The issue is complicated by the fact that phosphatases belong to multiple independently evolved families, which are rarely studied together. We undertook a loss-of-function RNA-interference-based screen of virtually all known (254) human phosphatases to understand their function in BDNF/TrkB-mediated neurite outgrowth in differentiated SH-SY5Y cells. This approach identified phosphatases from diverse families, which either positively or negatively modulate BDNF-TrkB-mediated neurite outgrowth, and most of which have little or no previously established function related to NT signaling. "Classical" protein tyrosine phosphatases (PTPs) accounted for 13% of the candidate regulatory phosphatases. The top classical PTP identified as a negative regulator of BDNF-TrkB-mediated neurite outgrowth was PTPN12 (also called PTP-PEST). Validation and follow-up studies showed that endogenous PTPN12 antagonizes tyrosine phosphorylation of TrkB itself, and the downstream activation of ERK1/2. We also found PTPN12 to negatively regulate phosphorylation of p130cas and FAK, proteins with previously described functions related to cell motility and growth cone behavior. Our data provide the first comprehensive survey of phosphatase function in NT signaling and neurite outgrowth. They reveal the complexity of phosphatase control, with several evolutionarily unrelated phosphatase families cooperating to affect this biological response, and hence the

  2. A Loss-of-Function Screen for Phosphatases that Regulate Neurite Outgrowth Identifies PTPN12 as a Negative Regulator of TrkB Tyrosine Phosphorylation

    PubMed Central

    Ambjørn, Malene; Dubreuil, Véronique; Miozzo, Federico; Nigon, Fabienne; Møller, Bente; Issazadeh-Navikas, Shohreh; Berg, Jacob; Lees, Michael; Sap, Jan

    2013-01-01

    Alterations in function of the neurotrophin BDNF are associated with neurodegeneration, cognitive decline, and psychiatric disorders. BDNF promotes axonal outgrowth and branching, regulates dendritic tree morphology and is important for axonal regeneration after injury, responses that largely result from activation of its tyrosine kinase receptor TrkB. Although intracellular neurotrophin (NT) signaling presumably reflects the combined action of kinases and phosphatases, little is known about the contributions of the latter to TrkB regulation. The issue is complicated by the fact that phosphatases belong to multiple independently evolved families, which are rarely studied together. We undertook a loss-of-function RNA-interference-based screen of virtually all known (254) human phosphatases to understand their function in BDNF/TrkB-mediated neurite outgrowth in differentiated SH-SY5Y cells. This approach identified phosphatases from diverse families, which either positively or negatively modulate BDNF-TrkB-mediated neurite outgrowth, and most of which have little or no previously established function related to NT signaling. “Classical” protein tyrosine phosphatases (PTPs) accounted for 13% of the candidate regulatory phosphatases. The top classical PTP identified as a negative regulator of BDNF-TrkB-mediated neurite outgrowth was PTPN12 (also called PTP-PEST). Validation and follow-up studies showed that endogenous PTPN12 antagonizes tyrosine phosphorylation of TrkB itself, and the downstream activation of ERK1/2. We also found PTPN12 to negatively regulate phosphorylation of p130cas and FAK, proteins with previously described functions related to cell motility and growth cone behavior. Our data provide the first comprehensive survey of phosphatase function in NT signaling and neurite outgrowth. They reveal the complexity of phosphatase control, with several evolutionarily unrelated phosphatase families cooperating to affect this biological response, and hence

  3. TrkB receptors are required for follicular growth and oocyte survival in the mammalian ovary

    PubMed Central

    Paredes, Alfonso; Romero, Carmen; Dissen, Gregory A.; DeChiara, Tom M.; Reichardt, Louis; Cornea, Anda; Ojeda, Sergio R.; Xu, Baoji

    2009-01-01

    Although it is well established that both follicular assembly and the initiation of follicle growth in the mammalian ovary occur independently of pituitary hormone support, the factors controlling these processes remain poorly understood. We now report that neurotrophins (NTs) signaling via TrkB receptors are required for the growth of newly formed follicles. Both neurotrophin-4/5 (NT-4) and brain-derived neurotrophic factor (BDNF), the preferred TrkB ligands, are expressed in the infantile mouse ovary. Initially, they are present in oocytes, but this site of expression switches to granulosa cells after the newly assembled primordial follicles develop into growing primary follicles. Full-length kinase domain-containing TrkB receptors are expressed at low and seemingly unchanging levels in the oocytes and granulosa cells of both primordial and growing follicles. In contrast, a truncated TrkB isoform lacking the intracellular domain of the receptor is selectively expressed in oocytes, where it is targeted to the cell membrane as primary follicles initiate growth. Using gene-targeted mice lacking all TrkB isoforms, we show that the ovaries of these mice or those lacking both NT-4 and BDNF suffer a stage-selective deficiency in early follicular development that compromises the ability of follicles to grow beyond the primary stage. Proliferation of granulosa cells— required for this transition—and expression of FSH receptors (FSHR), which reflects the degree of biochemical differentiation of growing follicles, are reduced in trkB-null mice. Ovaries from these animals grafted under the kidney capsule of wild-type mice fail to sustain follicular growth and show a striking loss of follicular organization, preceded by massive oocyte death. These results indicate that TrkB receptors are required for the early growth of ovarian follicles and that they exert this function by primarily supporting oocyte development as well as providing granulosa cells with a proliferative

  4. Dysregulation of TrkB phosphorylation and proBDNF protein in adenylyl cyclase 1 and 8 knockout mice in a model of fetal alcohol spectrum disorder

    PubMed Central

    Susick, Laura L.; Chrumka, Alexandria C.; Hool, Steven M.; Conti, Alana C.

    2017-01-01

    Brain-derived neurotrophic factor (BDNF) mediates neuron growth and is regulated by adenylyl cyclases (ACs). Mice lacking AC1/8 (DKO) have a basal reduction in the dendritic complexity of medium spiny neurons in the caudate putamen and demonstrate increased neurotoxicity in the striatum following acute neonatal ethanol exposure compared to wild type (WT) controls, suggesting a compromise in BDNF regulation under varying conditions. Although neonatal ethanol exposure can negatively impact BDNF expression, little is known about the effect on BDNF receptor activation and its downstream signaling, including Akt activation, an established neuroprotective pathway. Therefore, here we determined the effects of AC1/8 deletion and neonatal ethanol administration on BDNF and proBDNF protein expression, and activation of tropomyosin-related kinase B (TrkB), Akt, ERK1/2, and PLCγ. WT and DKO mice were treated with a single dose of 2.5 g/kg ethanol or saline at postnatal days 5–7 to model late-gestational alcohol exposure. Striatal and cortical tissues were analyzed using a BDNF enzyme-linked immunosorbent assay or immunoblotting for proBDNF, phosphorylated and total TrkB, Akt, ERK1/2, and PLCγ1. Neither postnatal ethanol exposure nor AC1/8 deletion affected total BDNF protein expression at any time point in either region examined. Neonatal ethanol increased the expression of proBDNF protein in the striatum of WT mice 6, 24, and 48 h after exposure, with DKO mice demonstrating a reduction in proBDNF expression 6 h after exposure. Six and 24 h after ethanol administration, phosphorylation of full-length TrkB in the striatum was significantly reduced in WT mice, but was significantly increased in DKO mice only at 24 h. Interestingly, 48 h after ethanol, both WT and DKO mice demonstrated a reduction in phosphorylated full-length TrkB. In addition, Akt and PLCγ1 phosphorylation was also decreased in ethanol-treated DKO mice 48 h after injection. These data demonstrate

  5. Dysregulation of TrkB phosphorylation and proBDNF protein in adenylyl cyclase 1 and 8 knockout mice in a model of fetal alcohol spectrum disorder.

    PubMed

    Susick, Laura L; Chrumka, Alexandria C; Hool, Steven M; Conti, Alana C

    2016-03-01

    Brain-derived neurotrophic factor (BDNF) mediates neuron growth and is regulated by adenylyl cyclases (ACs). Mice lacking AC1/8 (DKO) have a basal reduction in the dendritic complexity of medium spiny neurons in the caudate putamen and demonstrate increased neurotoxicity in the striatum following acute neonatal ethanol exposure compared to wild type (WT) controls, suggesting a compromise in BDNF regulation under varying conditions. Although neonatal ethanol exposure can negatively impact BDNF expression, little is known about the effect on BDNF receptor activation and its downstream signaling, including Akt activation, an established neuroprotective pathway. Therefore, here we determined the effects of AC1/8 deletion and neonatal ethanol administration on BDNF and proBDNF protein expression, and activation of tropomyosin-related kinase B (TrkB), Akt, ERK1/2, and PLCγ. WT and DKO mice were treated with a single dose of 2.5 g/kg ethanol or saline at postnatal days 5-7 to model late-gestational alcohol exposure. Striatal and cortical tissues were analyzed using a BDNF enzyme-linked immunosorbent assay or immunoblotting for proBDNF, phosphorylated and total TrkB, Akt, ERK1/2, and PLCɣ1. Neither postnatal ethanol exposure nor AC1/8 deletion affected total BDNF protein expression at any time point in either region examined. Neonatal ethanol increased the expression of proBDNF protein in the striatum of WT mice 6, 24, and 48 h after exposure, with DKO mice demonstrating a reduction in proBDNF expression 6 h after exposure. Six and 24 h after ethanol administration, phosphorylation of full-length TrkB in the striatum was significantly reduced in WT mice, but was significantly increased in DKO mice only at 24 h. Interestingly, 48 h after ethanol, both WT and DKO mice demonstrated a reduction in phosphorylated full-length TrkB. In addition, Akt and PLCɣ1 phosphorylation was also decreased in ethanol-treated DKO mice 48 h after injection. These data demonstrate

  6. Chronic Deprivation of TrkB Signaling Leads to Selective Late-onset Nigrostriatal Dopaminergic Degeneration

    PubMed Central

    Baydyuk, Maryna; Nguyen, Madeline T.; Xu, Baoji

    2011-01-01

    The pathological hallmark of Parkinson's disease (PD) is a selective and progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). In the vast majority of cases the appearance of PD is sporadic, and its etiology remains unknown. Several postmortem studies demonstrate reduced levels of brain-derived neurotrophic factor (BDNF) in the SNc of PD patients. Application of BDNF promotes the survival of DA neurons in PD animal models. Here we show that BDNF signaling via its TrkB receptor tyrosine kinase is important for survival of nigrostriatal DA neurons in aging brains. Immunohistochemistry revealed that the TrkB receptor was expressed in DA neurons located in the SNc and ventral tegmental area (VTA). However, a significant loss of DA neurons occurred at 12-24 months of age only in the SNc but not in the VTA of TrkB hypomorphic mice in which the TrkB receptor was expressed at a quarter to a third of the normal amount. The neuronal loss was accompanied by a decrease in dopaminergic axonal terminals in the striatum and by gliosis in both the SNc and striatum. Furthermore, nigrostriatal DA neurons in the TrkB mutant mice were hypersensitive to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a mitochondrial complex I inhibitor that selectively kills DA neurons. These results suggest that BDNF-to-TrkB signaling plays an important role in the long-term maintenance of the nigrostriatal system and that its deficiency may contribute to the progression of PD. PMID:21192928

  7. Stabilization of the cysteine-rich conotoxin MrIA by using a 1,2,3-triazole as a disulfide bond mimetic.

    PubMed

    Gori, Alessandro; Wang, Ching-I A; Harvey, Peta J; Rosengren, K Johan; Bhola, Rebecca F; Gelmi, Maria L; Longhi, Renato; Christie, Macdonald J; Lewis, Richard J; Alewood, Paul F; Brust, Andreas

    2015-01-19

    The design of disulfide bond mimetics is an important strategy for optimising cysteine-rich peptides in drug development. Mimetics of the drug lead conotoxin MrIA, in which one disulfide bond is selectively replaced of by a 1,4-disubstituted-1,2,3-triazole bridge, are described. Sequential copper-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction) followed by disulfide formation resulted in the regioselective syntheses of triazole-disulfide hybrid MrIA analogues. Mimetics with a triazole replacing the Cys4-Cys13 disulfide bond retained tertiary structure and full in vitro and in vivo activity as norepinephrine reuptake inhibitors. Importantly, these mimetics are resistant to reduction in the presence of glutathione, thus resulting in improved plasma stability and increased suitability for drug development. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Neurotrophin modulation of voltage-gated potassium channels in rat through TrkB receptors is time and sensory experience dependent

    PubMed Central

    Tucker, K; Fadool, DA

    2002-01-01

    The whole-cell configuration of the patch-clamp technique, immunoprecipitation experiments and unilateral naris occlusions were used to investigate whether the voltage-gated potassium channel Kv1.3 was a substrate for neurotrophin-induced tyrosine phosphorylation and subsequent functional modulation of current properties in cultured rat olfactory bulb (OB) neurons. Membrane proteins of the OB included all three Trk receptor kinases, but the truncated form of the receptor, lacking an intact kinase domain, was the predominant form of the protein for TrkA and TrkC, while TrkB was predominantly found as the full-length receptor. Acute (15 min) stimulation of OB neurons with bath application of 50 ng ml−1 brain-derived neurotrophic factor (BDNF), which is a selective ligand for TrkB, caused suppression of the whole-cell outward current and no changes in the kinetics of inactivation or deactivation. Acute stimulation with either nerve growth factor or neurotrophin-3 failed to evoke any changes in Kv1.3 function in the OB neurons. Chronic exposure to BDNF (days) caused an increase in the magnitude of Kv1.3 current and speeding of the inactivation and deactivation of the channel. Acute BDNF-induced activation of TrkB receptors significantly increased tyrosine phosphorylation of Kv1.3 in the OB, as shown using a combined immunoprecipitation and Western blot analysis. With unilateral naris occlusion, the acute BDNF-induced tyrosine phosphorylation of Kv1.3 was increased in neurons lacking odour sensory experience. In summary, the duration of neurotrophin exposure and the sensory-dependent state of a neuron can influence the degree of phosphorylation of a voltage-gated ion channel and its concomitant functional modulation by neurotrophins. PMID:12122142

  9. BDNF/ TrkB interaction regulates migration of SVZ precursor cells via PI3-K and MAP-K signalling pathways.

    PubMed

    Chiaramello, S; Dalmasso, G; Bezin, L; Marcel, D; Jourdan, F; Peretto, P; Fasolo, A; De Marchis, S

    2007-10-01

    Neuroblasts born in the subventricular zone (SVZ) migrate along the rostral migratory stream, reaching the olfactory bulb (OB) where they differentiate into local interneurons. Several extracellular factors have been suggested to control specific steps of this process. The brain-derived neurotrophic factor (BDNF) has been demonstrated to promote morphological differentiation and survival of OB interneurons. Here we show that BDNF and its receptor TrkB are expressed in vivo throughout the migratory pathway, implying that BDNF might also mediate migratory signals. By using in vitro models we demonstrate that BDNF promotes migration of SVZ neuroblasts, acting both as inducer and attractant through TrkB activation. We show that BDNF induces cAMP response element-binding protein (CREB) activation in migrating neuroblasts via phosphatidylinositol 3-kinase (PI3-K) and mitogen-activated protein kinase (MAP-K) signalling. Pharmacological blockade of these pathways on SVZ explants significantly reduces CREB activation and impairs neuronal migration. This study identifies a function of BDNF in the SVZ system, which involves multiple protein kinase pathways leading to neuroblast migration.

  10. Type I Collagen and Collagen Mimetics as Angiogenesis Promoting Superpolymers

    SciTech Connect

    Twardowski, T.; Fertala, A.; Orgel, J.P.R.O.; San Antonio, J.D.

    2008-07-18

    Angiogenesis, the development of blood vessels from the pre-existing vasculature, is a key component of embryogenesis and tissue regeneration. Angiogenesis also drives pathologies such as tumor growth and metastasis, and hemangioma development in newborns. On the other hand, promotion of angiogenesis is needed in tissues with vascular insufficiencies, and in bioengineering, to endow tissue substitutes with appropriate microvasculatures. Therefore, much research has focused on defining mechanisms of angiogenesis, and identifying pro- and anti-angiogenic molecules. Type I collagen, the most abundant protein in humans, potently stimulates angiogenesis in vitro and in vivo. Crucial to its angiogenic activity appears to be ligation and possibly clustering of endothelial cell (EC) surface {alpha}1{beta}1/{alpha}2{beta}1 integrin receptors by the GFPGER502-507 sequence of the collagen fibril. However, additional aspects of collagen structure and function that may modulate its angiogenic properties are discussed. Moreover, type I collagen and fibrin, another angiogenic polymer, share several structural features. These observations suggest strategies for creating 'angiogenic superpolymers', including: modifying type I collagen to influence its biological half-life, immunogenicity, and integrin binding capacity; genetically engineering fibrillar collagens to include additional integrin binding sites or angiogenic determinants, and remove unnecessary or deleterious sequences without compromising fibril integrity; and exploring the suitability of poly(ortho ester), PEG-lysine copolymer, tubulin, and cholesteric cuticle as collagen mimetics, and suggesting means of modifying them to display ideal angiogenic properties. The collagenous and collagen mimetic angiogenic superpolymers described here may someday prove useful for many applications in tissue engineering and human medicine.

  11. Experience-dependent regulation of TrkB isoforms in rodent visual cortex.

    PubMed

    Bracken, Bethany K; Turrigiano, Gina G

    2009-04-01

    Within primary visual cortex (V1), brain-derived neurotrophic factor (BDNF) signaling through its high-affinity receptor TrkB is important for normal development and experience-dependent plasticity. TrkB is expressed in several alternatively spliced isoforms, including full-length TrkB (TrkB.FL), and several truncated isoforms (TrkB.T1, TrkB.T2, and TrkB.T4) that lack the intracellular tyrosine kinase domain. These isoforms are important components of BDNF signaling, yet little is known about the developmental or experience-dependent regulation of their expression. Using immunohistochemistry, we found TrkB.FL and TrkB.T1 expressed in interneurons and pyramidal neurons within V1, but not in cortical astrocytes. We used real-time PCR to quantify the changes in mRNA expression of BDNF, the four TrkB isoforms, and the low-affinity receptor P75NTR during normal development, and in response to visual deprivation at two different ages. BDNF expression increased between postnatal days 10 (P10) and P30, and was rapidly down-regulated by 3 days of visual deprivation during both the pre-critical period (P14-P17) and the critical period (P18-P21). Over the same developmental period, expression of each TrkB isoform was regulated independently; TrkB.T1 increased, TrkB.FL and TrkB.T2 decreased, and TrkB.T4 showed transient changes. Neither brief visual deprivation nor prolonged dark-rearing induced changes in either TrkB.FL or TrkB.T1 expression. However, TrkB.T4 expression was reduced by brief visual deprivation, whereas TrkB.T4, TrkB.T2 and P75(NTR) were up-regulated by prolonged dark-rearing into the critical period. Our data indicate that TrkB isoform expression can be selectively regulated by visual experience, and may contribute to experience-dependent cortical plasticity.

  12. Inhibiting NANOG Enhances Efficacy of BH3 Mimetics | Center for Cancer Research

    Cancer.gov

    BCL-2 family proteins regulate cell fate. Some members promote cell survival while others induce programmed cell death. A third group, the BH3-only members, modulates the activities of the rest of the family. Some cancers, including those of the colon and rectum, express elevated levels of pro-survival BCL-2 members, which may protect cancer cells from chemotherapy. BH3 mimetics are novel therapies that target and inhibit these pro-survival family members. Two in particular, ABT-737 and ABT-199, have activity against multiple cancer types, though neither targets the protein MCL-1, which is related to the BCL-2 family and causes resistance to the BH3 mimetics. Recent studies have revealed that the embryonic regulator NANOG and the related gene NANOGP8 can indirectly regulate MCL-1 via the kinase AKT. Abid Mattoo, Ph.D., J. Milburn Jessup, M.D., and colleagues of CCR’s Laboratory of Experimental Carcinogenesis, hypothesized that combining NANOG or NANOGP8 inhibition with a BH3 mimetic would enhance the latter’s anticancer activity.

  13. Polyketide mimetics yield structural and mechanistic insights into product template domain function in nonreducing polyketide synthases.

    PubMed

    Barajas, Jesus F; Shakya, Gaurav; Moreno, Gabriel; Rivera, Heriberto; Jackson, David R; Topper, Caitlyn L; Vagstad, Anna L; La Clair, James J; Townsend, Craig A; Burkart, Michael D; Tsai, Shiou-Chuan

    2017-05-23

    Product template (PT) domains from fungal nonreducing polyketide synthases (NR-PKSs) are responsible for controlling the aldol cyclizations of poly-β-ketone intermediates assembled during the catalytic cycle. Our ability to understand the high regioselective control that PT domains exert is hindered by the inaccessibility of intrinsically unstable poly-β-ketones for in vitro studies. We describe here the crystallographic application of "atom replacement" mimetics in which isoxazole rings linked by thioethers mimic the alternating sites of carbonyls in the poly-β-ketone intermediates. We report the 1.8-Å cocrystal structure of the PksA PT domain from aflatoxin biosynthesis with a heptaketide mimetic tethered to a stably modified 4'-phosphopantetheine, which provides important empirical evidence for a previously proposed mechanism of PT-catalyzed cyclization. Key observations support the proposed deprotonation at C4 of the nascent polyketide by the catalytic His1345 and the role of a protein-coordinated water network to selectively activate the C9 carbonyl for nucleophilic addition. The importance of the 4'-phosphate at the distal end of the pantetheine arm is demonstrated to both facilitate delivery of the heptaketide mimetic deep into the PT active site and anchor one end of this linear array to precisely meter C4 into close proximity to the catalytic His1345. Additional structural features, docking simulations, and mutational experiments characterize protein-substrate mimic interactions, which likely play roles in orienting and stabilizing interactions during the native multistep catalytic cycle. These findings afford a view of a polyketide "atom-replaced" mimetic in a NR-PKS active site that could prove general for other PKS domains.

  14. Differential effects of superoxide dismutase and superoxide dismutase/catalase mimetics on human breast cancer cells.

    PubMed

    Shah, Manisha H; Liu, Guei-Sheung; Thompson, Erik W; Dusting, Gregory J; Peshavariya, Hitesh M

    2015-04-01

    Reactive oxygen species (ROS) such as superoxide and hydrogen peroxide (H2O2) have been implicated in development and progression of breast cancer. In the present study, we have evaluated the effects of the superoxide dismutase (SOD) mimetic MnTmPyP and the SOD/catalase mimetic EUK 134 on superoxide and H2O2 formation as well as proliferation, adhesion, and migration of MCF-7 and MDA-MB-231 cells. Superoxide and H2O2 production was examined using dihydroethidium and Amplex red assays, respectively. Cell viability and adhesion were measured using a tetrazolium-based MTT assay. Cell proliferation was determined using trypan blue assay. Cell cycle progression was analyzed using flow cytometry. Clonal expansion of a single cell was performed using a colony formation assay. Cell migration was measured using transwell migration assay. Dual luciferase assay was used to determine NF-κB reporter activity. EUK 134 effectively reduced both superoxide and H2O2, whereas MnTmPyP removed superoxide but enhanced H2O2 formation. EUK 134 effectively attenuated viability, proliferation, clonal expansion, adhesion, and migration of MCF-7 and MDA-MB-231 cells. In contrast, MnTmPyP only reduced clonal expansion of MCF-7 and MDA-MB-231 cells but had no effect on adhesion and cell cycle progression. Tumor necrosis factor-alpha-induced NF-κB activity was reduced by EUK 134, whereas MnTmPyP enhanced this activity. These data indicate that the SOD mimetic MnTmPyP and the SOD/catalase mimetic EUK 134 exert differential effects on breast cancer cell growth. Inhibition of H2O2 signaling using EUK 134-like compound might be a promising approach to breast cancer therapy.

  15. Functional Mimetics of the HIV-1 CCR5 Co-Receptor Displayed on the Surface of Magnetic Liposomes.

    PubMed

    Kuzmina, Alona; Vaknin, Karin; Gdalevsky, Garik; Vyazmensky, Maria; Marks, Robert S; Taube, Ran; Engel, Stanislav

    2015-01-01

    Chemokine G protein coupled receptors, principally CCR5 or CXCR4, function as co-receptors for HIV-1 entry into CD4+ T cells. Initial binding of the viral envelope glycoprotein (Env) gp120 subunit to the host CD4 receptor induces a cascade of structural conformational changes that lead to the formation of a high-affinity co-receptor-binding site on gp120. Interaction between gp120 and the co-receptor leads to the exposure of epitopes on the viral gp41 that mediates fusion between viral and cell membranes. Soluble CD4 (sCD4) mimetics can act as an activation-based inhibitor of HIV-1 entry in vitro, as it induces similar structural changes in gp120, leading to increased virus infectivity in the short term but to virus Env inactivation in the long term. Despite promising clinical implications, sCD4 displays low efficiency in vivo, and in multiple HIV strains, it does not inhibit viral infection. This has been attributed to the slow kinetics of the sCD4-induced HIV Env inactivation and to the failure to obtain sufficient sCD4 mimetic levels in the serum. Here we present uniquely structured CCR5 co-receptor mimetics. We hypothesized that such mimetics will enhance sCD4-induced HIV Env inactivation and inhibition of HIV entry. Co-receptor mimetics were derived from CCR5 gp120-binding epitopes and functionalized with a palmitoyl group, which mediated their display on the surface of lipid-coated magnetic beads. CCR5-peptidoliposome mimetics bound to soluble gp120 and inhibited HIV-1 infectivity in a sCD4-dependent manner. We concluded that CCR5-peptidoliposomes increase the efficiency of sCD4 to inhibit HIV infection by acting as bait for sCD4-primed virus, catalyzing the premature discharge of its fusion potential.

  16. Functional Mimetics of the HIV-1 CCR5 Co-Receptor Displayed on the Surface of Magnetic Liposomes

    PubMed Central

    Kuzmina, Alona; Vaknin, Karin; Gdalevsky, Garik; Vyazmensky, Maria; Marks, Robert S.; Taube, Ran

    2015-01-01

    Chemokine G protein coupled receptors, principally CCR5 or CXCR4, function as co-receptors for HIV-1 entry into CD4+ T cells. Initial binding of the viral envelope glycoprotein (Env) gp120 subunit to the host CD4 receptor induces a cascade of structural conformational changes that lead to the formation of a high-affinity co-receptor-binding site on gp120. Interaction between gp120 and the co-receptor leads to the exposure of epitopes on the viral gp41 that mediates fusion between viral and cell membranes. Soluble CD4 (sCD4) mimetics can act as an activation-based inhibitor of HIV-1 entry in vitro, as it induces similar structural changes in gp120, leading to increased virus infectivity in the short term but to virus Env inactivation in the long term. Despite promising clinical implications, sCD4 displays low efficiency in vivo, and in multiple HIV strains, it does not inhibit viral infection. This has been attributed to the slow kinetics of the sCD4-induced HIV Env inactivation and to the failure to obtain sufficient sCD4 mimetic levels in the serum. Here we present uniquely structured CCR5 co-receptor mimetics. We hypothesized that such mimetics will enhance sCD4-induced HIV Env inactivation and inhibition of HIV entry. Co-receptor mimetics were derived from CCR5 gp120-binding epitopes and functionalized with a palmitoyl group, which mediated their display on the surface of lipid-coated magnetic beads. CCR5-peptidoliposome mimetics bound to soluble gp120 and inhibited HIV-1 infectivity in a sCD4-dependent manner. We concluded that CCR5-peptidoliposomes increase the efficiency of sCD4 to inhibit HIV infection by acting as bait for sCD4-primed virus, catalyzing the premature discharge of its fusion potential. PMID:26629902

  17. A spectral mimetic least-squares method

    DOE PAGES

    Bochev, Pavel; Gerritsma, Marc

    2014-09-01

    We present a spectral mimetic least-squares method for a model diffusion–reaction problem, which preserves key conservation properties of the continuum problem. Casting the model problem into a first-order system for two scalar and two vector variables shifts material properties from the differential equations to a pair of constitutive relations. We also use this system to motivate a new least-squares functional involving all four fields and show that its minimizer satisfies the differential equations exactly. Discretization of the four-field least-squares functional by spectral spaces compatible with the differential operators leads to a least-squares method in which the differential equations are alsomore » satisfied exactly. Additionally, the latter are reduced to purely topological relationships for the degrees of freedom that can be satisfied without reference to basis functions. Furthermore, numerical experiments confirm the spectral accuracy of the method and its local conservation.« less

  18. A spectral mimetic least-squares method

    SciTech Connect

    Bochev, Pavel; Gerritsma, Marc

    2014-09-01

    We present a spectral mimetic least-squares method for a model diffusion–reaction problem, which preserves key conservation properties of the continuum problem. Casting the model problem into a first-order system for two scalar and two vector variables shifts material properties from the differential equations to a pair of constitutive relations. We also use this system to motivate a new least-squares functional involving all four fields and show that its minimizer satisfies the differential equations exactly. Discretization of the four-field least-squares functional by spectral spaces compatible with the differential operators leads to a least-squares method in which the differential equations are also satisfied exactly. Additionally, the latter are reduced to purely topological relationships for the degrees of freedom that can be satisfied without reference to basis functions. Furthermore, numerical experiments confirm the spectral accuracy of the method and its local conservation.

  19. A safe lithium mimetic for bipolar disorder.

    PubMed

    Singh, Nisha; Halliday, Amy C; Thomas, Justyn M; Kuznetsova, Olga V; Baldwin, Rhiannon; Woon, Esther C Y; Aley, Parvinder K; Antoniadou, Ivi; Sharp, Trevor; Vasudevan, Sridhar R; Churchill, Grant C

    2013-01-01

    Lithium is the most effective mood stabilizer for the treatment of bipolar disorder, but it is toxic at only twice the therapeutic dosage and has many undesirable side effects. It is likely that a small molecule could be found with lithium-like efficacy but without toxicity through target-based drug discovery; however, therapeutic target of lithium remains equivocal. Inositol monophosphatase is a possible target but no bioavailable inhibitors exist. Here we report that the antioxidant ebselen inhibits inositol monophosphatase and induces lithium-like effects on mouse behaviour, which are reversed with inositol, consistent with a mechanism involving inhibition of inositol recycling. Ebselen is part of the National Institutes of Health Clinical Collection, a chemical library of bioavailable drugs considered clinically safe but without proven use. Therefore, ebselen represents a lithium mimetic with the potential both to validate inositol monophosphatase inhibition as a treatment for bipolar disorder and to serve as a treatment itself.

  20. Peptide Mimetics of Apolipoproteins Improve HDL Function

    PubMed Central

    Navab, Mohamad; Anantharamaiah, G. M.; Reddy, Srinivasa T.; Van Lenten, Brian J.; Buga, Georgette M.; Fogelman, Alan M.

    2007-01-01

    Over the past decade evidence has accumulated that suggests that the anti-inflammatory properties of HDL may be at least as important as the levels of HDL-cholesterol. The recent failure of the torcetrapib clinical trails has highlighted the potential differences between HDL-cholesterol levels and HDL function. Agents to improve HDL function including HDL anti-inflammatory properties provide a new therapeutic strategy for ameliorating atherosclerosis and other chronic inflammatory conditions related to dyslipidemia. Seeking guidance from the structure of the apolipoproteins of the plasma lipoproteins has allowed the creation of a series of polypeptides that have interesting functionality with therapeutic implications. In animal models of atherosclerosis, peptide mimetics of apolipoproteins have been shown to improve the anti-inflammatory properties of HDL, significantly reduce lesions and improve vascular inflammation and function without necessarily altering HDL-cholesterol levels. Some of these are now entering the clinical arena as interventions in pharmacologic and pharmacodynamic studies. PMID:18449337

  1. Folate Receptor-Targeting Gold Nanoclusters as Fluorescence Enzyme Mimetic Nanoprobes for Tumor Molecular Colocalization Diagnosis

    PubMed Central

    Hu, Dehong; Sheng, Zonghai; Fang, Shengtao; Wang, Yanan; Gao, Duyang; Zhang, Pengfei; Gong, Ping; Ma, Yifan; Cai, Lintao

    2014-01-01

    Nanoprobes with enzyme-like properties attracted a growing interest in early screening and diagnosis of cancer. To achieve high accuracy and specificity of tumor detection, the design and preparation of enzyme mimetic nanoprobes with high enzyme activity, tumor targeting and excellent luminescence property is highly desirable. Herein, we described a novel kind of fluorescence enzyme mimetic nanoprobe based on folate receptor-targeting Au nanoclusters. The nanoprobes exhibited excellent stability, low cytotoxicity, high fluorescence and enzyme activity. We demonstrated that the nanoprobes could be used for tumor tissues fluorescence/visualizing detection. For the same tumor tissue slice, the nanoprobes peroxidase staining and fluorescent staining were obtained simultaneously, and the results were mutually complementary. Therefore, the fluorescence enzyme mimetic nanoprobes could provide a molecular colocalization diagnosis strategy, efficiently avoid false-positive and false-negative results, and further improve the accuracy and specificity of cancer diagnoses. By examining different clinical samples, we demonstrated that the nanoprobes could distinguish efficiently cancerous cells from normal cells, and exhibit a clinical potential for cancer diagnosis. PMID:24465272

  2. Supramolecular assembly of multifunctional maspin-mimetic nanostructures as a potent peptide-based angiogenesis inhibitor

    SciTech Connect

    Zha, R. Helen; Sur, Shantanu; Boekhoven, Job; Shi, Heidi Y.; Zhang, Ming; Stupp, Samuel I.

    2014-11-08

    Aberrant angiogenesis plays a large role in pathologies ranging from tumor growth to macular degeneration. Anti-angiogenic proteins have thus come under scrutiny as versatile, potent therapeutics but face problems with purification and tissue retention. We report here on the synthesis of supramolecular nanostructures that mimic the anti-angiogenic activity of maspin, a class II tumor suppressor protein. These maspin-mimetic nanostructures are formed via self-assembly of small peptide amphiphiles containing the g-helix motif of maspin. Using tubulogenesis assays with human umbilical vein endothelial cells, we demonstrate that maspin-mimetic nanostructures show anti-angiogenic activity at concentrations that are significantly lower than those necessary for the g-helix peptide. Furthermore, in vivo assays in the chick chorioallantoic membrane show maspin-mimetic nanostructures to be effective over controls at inhibiting angiogenesis. Thus, in conclusion, the nanostructures investigated here offer an attractive alternative to the use of anti-angiogenic recombinant proteins in the treatment of cancer or other diseases involving abnormal blood vessel formation.

  3. Supramolecular assembly of multifunctional maspin-mimetic nanostructures as a potent peptide-based angiogenesis inhibitor

    DOE PAGES

    Zha, R. Helen; Sur, Shantanu; Boekhoven, Job; ...

    2014-11-08

    Aberrant angiogenesis plays a large role in pathologies ranging from tumor growth to macular degeneration. Anti-angiogenic proteins have thus come under scrutiny as versatile, potent therapeutics but face problems with purification and tissue retention. We report here on the synthesis of supramolecular nanostructures that mimic the anti-angiogenic activity of maspin, a class II tumor suppressor protein. These maspin-mimetic nanostructures are formed via self-assembly of small peptide amphiphiles containing the g-helix motif of maspin. Using tubulogenesis assays with human umbilical vein endothelial cells, we demonstrate that maspin-mimetic nanostructures show anti-angiogenic activity at concentrations that are significantly lower than those necessary formore » the g-helix peptide. Furthermore, in vivo assays in the chick chorioallantoic membrane show maspin-mimetic nanostructures to be effective over controls at inhibiting angiogenesis. Thus, in conclusion, the nanostructures investigated here offer an attractive alternative to the use of anti-angiogenic recombinant proteins in the treatment of cancer or other diseases involving abnormal blood vessel formation.« less

  4. Amylin structure-function relationships and receptor pharmacology: implications for amylin mimetic drug development.

    PubMed

    Bower, Rebekah L; Hay, Debbie L

    2016-06-01

    Amylin is an important, but poorly understood, 37 amino acid glucoregulatory hormone with great potential to target metabolic diseases. A working example that the amylin system is one worth developing is the FDA-approved drug used in insulin-requiring diabetic patients, pramlintide. However, certain characteristics of pramlintide pharmacokinetics and formulation leave considerable room for further development of amylin-mimetic compounds. Given that amylin-mimetic drug design and development is an active area of research, surprisingly little is known about the structure/function relationships of amylin. This is largely due to the unfavourable aggregative and solubility properties of the native peptide sequence, which are further complicated by the composition of amylin receptors. These are complexes of the calcitonin receptor with receptor activity-modifying proteins. This review explores what is known of the structure-function relationships of amylin and provides insights that can be drawn from the closely related peptide, CGRP. We also describe how this information is aiding the development of more potent and stable amylin mimetics, including peptide hybrids.

  5. Design and synthesis of a protein. beta. -turn mimetic

    SciTech Connect

    Olson, G.L.; Voss, M.E.; Hill, D.E.; Kahn, M.; Madison, V.S.; Cook, C.M. )

    1990-01-03

    A nine-membered-ring lactam system (1) has been chosen as a framework for the development of non-peptide molecules to mimic structural features of peptide and protein {beta}-turns. The synthesis of model di- and tetrapeptide mimetics starting from 1,5-cyclooctadiene derivatives is reported. In the model dipeptide mimetic (9), the amide linkages is trans (NMR, X-ray) and functional groups at positions adjacent to the lactam amide bond correspond closely to the side-chain positions of residues i + 1 and i + 2 of classical type II{prime} {beta}-turns. In the model tetrapeptide mimetic (30), all four side chains of low-energy trans amide conformers of the mimetic are well matched to their peptide counterparts.

  6. Crossmodal Modulation of Spatial Localization by Mimetic Words

    PubMed Central

    Yamada, Yuki; Miura, Kayo

    2016-01-01

    The present study investigated whether aurally presented mimetic words affect the judgment of the final position of a moving object. In Experiment 1, horizontal apparent motion of a visual target was presented, and an auditory mimetic word of “byun” (representing rapid forward motion), “pitari” (representing stop of motion), or “nisahi” (nonsense syllable) was presented via headphones. Observers were asked to judge which of two test stimuli was horizontally aligned with the target. The results showed that forward displacement in the “pitari” condition was significantly smaller than in the “byun” and “nisahi” conditions. However, when non-mimetic but meaningful words were presented (Experiment 2), this effect did not occur. Our findings suggest that the mimetic words, especially that meaning stop of motion, affect spatial localization by means of mental imagery regarding “stop” established by the phonological information of the word. PMID:27994845

  7. Understanding Mimetic Documents through "Knowledge Modeling" (Understanding Documents).

    ERIC Educational Resources Information Center

    Kirsch, Irwin S.; Mosenthal, Peter B.

    1991-01-01

    Shows how the scheme for understanding mimetic documents in previous columns can be used as a framework for understanding the levels of knowledge that make up John Anderson's "declarative stage." (RS)

  8. A neuron-specific cytoplasmic dynein isoform preferentially transports TrkB signaling endosomes

    PubMed Central

    Ha, Junghoon; Lo, Kevin W.-H.; Myers, Kenneth R.; Carr, Tiffany M.; Humsi, Michael K.; Rasoul, Bareza A.; Segal, Rosalind A.; Pfister, K. Kevin

    2008-01-01

    Cytoplasmic dynein is the multisubunit motor protein for retrograde movement of diverse cargoes to microtubule minus ends. Here, we investigate the function of dynein variants, defined by different intermediate chain (IC) isoforms, by expressing fluorescent ICs in neuronal cells. Green fluorescent protein (GFP)–IC incorporates into functional dynein complexes that copurify with membranous organelles. In living PC12 cell neurites, GFP–dynein puncta travel in both the anterograde and retrograde directions. In cultured hippocampal neurons, neurotrophin receptor tyrosine kinase B (TrkB) signaling endosomes are transported by cytoplasmic dynein containing the neuron-specific IC-1B isoform and not by dynein containing the ubiquitous IC-2C isoform. Similarly, organelles containing TrkB isolated from brain by immunoaffinity purification also contain dynein with IC-1 but not IC-2 isoforms. These data demonstrate that the IC isoforms define dynein populations that are selectively recruited to transport distinct cargoes. PMID:18559670

  9. Evaluation of TrkB and BDNF transcripts in prefrontal cortex, hippocampus, and striatum from subjects with schizophrenia, bipolar disorder, and major depressive disorder.

    PubMed

    Reinhart, Veronica; Bove, Susan E; Volfson, Dmitri; Lewis, David A; Kleiman, Robin J; Lanz, Thomas A

    2015-05-01

    Brain-derived neurotrophic factor (BDNF) signaling is integral to a range of neural functions, including synaptic plasticity and exhibits activity-dependent regulation of expression. As altered BDNF signaling has been implicated in multiple psychiatric diseases, here we report a quantitative reverse transcription polymerase chain reaction (RT-PCR) analysis of mRNAs encoding TrkB, total BDNF, and the four most abundant BDNF transcripts (I, IIc, IV, and VI) in postmortem tissue from matched tetrads of subjects with schizophrenia, bipolar disorder, or major depressive disorder (MDD) and healthy comparison subjects. In all three regions examined, dorsolateral prefrontal cortex (DLPFC), associative striatum and hippocampus, total BDNF mRNA levels did not differ in any disease state. In DLPFC, BDNF IIc was significantly lower in schizophrenia relative to healthy comparison subjects. In hippocampus, BDNF I, IIc, and VI were lower in subjects with both schizophrenia and bipolar disorder relative to comparison subjects. In striatum, TrkB mRNA was lower in bipolar disorder and MDD, while BDNF IIc was elevated in MDD, relative to comparison subjects. These data highlight potential alterations in BDNF signaling in the corticohippocampal circuit in schizophrenia, and within the striatum in mood disorders. Novel therapies aimed at improving BDNF-TrkB signaling may therefore have potential to impact on a range of psychiatric disorders. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Transactivation of TrkB by Sigma-1 receptor mediates cocaine-induced changes in dendritic spine density and morphology in hippocampal and cortical neurons

    PubMed Central

    Ka, Minhan; Kook, Yeon-Hee; Liao, Ke; Buch, Shilpa; Kim, Woo-Yang

    2016-01-01

    Cocaine is a highly addictive narcotic associated with dendritic spine plasticity in the striatum. However, it remains elusive whether cocaine modifies spines in a cell type-specific or region-specific manner or whether it alters different types of synapses in the brain. In addition, there is a paucity of data on the regulatory mechanism(s) involved in cocaine-induced modification of spine density. In the current study, we report that cocaine exposure differentially alters spine density, spine morphology, and the types of synapses in hippocampal and cortical neurons. Cocaine exposure in the hippocampus resulted in increased spine density, but had no significant effect on cortical neurons. Although cocaine exposure altered spine morphology in both cell types, the patterns of spine morphology were distinct for each cell type. Furthermore, we observed that cocaine selectively affects the density of excitatory synapses. Intriguingly, in hippocampal neurons cocaine-mediated effects on spine density and morphology involved sigma-1 receptor (Sig-1 R) and its downstream TrkB signaling, which were not the case in cortical neurons. Furthermore, pharmacological inhibition of Sig-1 R prevented cocaine-induced TrkB activation in hippocampal neurons. Our findings reveal a novel mechanism by which cocaine induces selective changes in spine morphology, spine density, and synapse formation, and could provide insights into the cellular basis for the cognitive impairment observed in cocaine addicts. PMID:27735948

  11. Transactivation of TrkB by Sigma-1 receptor mediates cocaine-induced changes in dendritic spine density and morphology in hippocampal and cortical neurons.

    PubMed

    Ka, Minhan; Kook, Yeon-Hee; Liao, Ke; Buch, Shilpa; Kim, Woo-Yang

    2016-10-13

    Cocaine is a highly addictive narcotic associated with dendritic spine plasticity in the striatum. However, it remains elusive whether cocaine modifies spines in a cell type-specific or region-specific manner or whether it alters different types of synapses in the brain. In addition, there is a paucity of data on the regulatory mechanism(s) involved in cocaine-induced modification of spine density. In the current study, we report that cocaine exposure differentially alters spine density, spine morphology, and the types of synapses in hippocampal and cortical neurons. Cocaine exposure in the hippocampus resulted in increased spine density, but had no significant effect on cortical neurons. Although cocaine exposure altered spine morphology in both cell types, the patterns of spine morphology were distinct for each cell type. Furthermore, we observed that cocaine selectively affects the density of excitatory synapses. Intriguingly, in hippocampal neurons cocaine-mediated effects on spine density and morphology involved sigma-1 receptor (Sig-1 R) and its downstream TrkB signaling, which were not the case in cortical neurons. Furthermore, pharmacological inhibition of Sig-1 R prevented cocaine-induced TrkB activation in hippocampal neurons. Our findings reveal a novel mechanism by which cocaine induces selective changes in spine morphology, spine density, and synapse formation, and could provide insights into the cellular basis for the cognitive impairment observed in cocaine addicts.

  12. Role of TrkB during the postnatal development of the rat carotid body.

    PubMed

    Bavis, Ryan W; Blegen, Halward J; Logan, Sarah; Fallon, Sarah C; McDonough, Amy B

    2015-12-01

    Brain-derived neurotrophic factor (BDNF) supports innervation of the carotid body by neurons projecting from the petrosal ganglion. Although carotid body glomus cells also express TrkB, BDNF's high affinity receptor, the role of BDNF in carotid body growth and O2 sensitivity has not been studied. Neonatal rats were treated with the TrkB antagonist K252a (100 μg kg(-1), i.p., b.i.d.) or vehicle on postnatal days P0-P6 and studied on P7. Carotid body volume was decreased by 35% after chronic K252a (P<0.001); a reduction in carotid body size was also elicited using the more selective TrkB antagonist ANA-12 (500 μg kg(-1), i.p., b.i.d.). In contrast, single-unit chemoafferent responses to 5% O2, measured in vitro, were unaffected by chronic K252a administration. Normoxic and hypoxic ventilation, measured by head-body plethysmography, were also normal after chronic K252a administration, but acute K252a administration produced a slower, deeper breathing pattern during the transition into hypoxia. These data suggest that BDNF regulates postnatal carotid body growth but does not influence the development of glomus cell O2 sensitivity. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Role of TrkB during the postnatal development of the rat carotid body

    PubMed Central

    Bavis, Ryan W.; Blegen, Halward J.; Logan, Sarah; Fallon, Sarah C.; McDonough, Amy B.

    2015-01-01

    Brain-derived neurotrophic factor (BDNF) supports innervation of the carotid body by neurons projecting from the petrosal ganglion. Although carotid body glomus cells also express TrkB, BDNF’s high affinity receptor, the role of BDNF in carotid body growth and O2 sensitivity has not been studied. Neonatal rats were treated with the TrkB antagonist K252a (100 μg kg−1, i.p., b.i.d.) or vehicle on postnatal days P0–P6 and studied on P7. Carotid body volume was decreased by 35% after chronic K252a (P<0.001); a reduction in carotid body size was also elicited using the more selective TrkB antagonist ANA-12 (500 μg kg−1, i.p., b.i.d.). In contrast, single-unit chemoafferent responses to 5% O2, measured in vitro, were unaffected by chronic K252a administration. Normoxic and hypoxic ventilation, measured by head-body plethysmography, were also normal after chronic K252a administration, but acute K252a administration produced a slower, deeper breathing pattern during the transition into hypoxia. These data suggest that BDNF regulates postnatal carotid body growth but does not influence the development of glomus cell O2 sensitivity. PMID:26222433

  14. Glycosaminoglycan mimetic improves enrichment and cell functions of human endothelial progenitor cell colonies.

    PubMed

    Chevalier, Fabien; Lavergne, Mélanie; Negroni, Elisa; Ferratge, Ségolène; Carpentier, Gilles; Gilbert-Sirieix, Marie; Siñeriz, Fernando; Uzan, Georges; Albanese, Patricia

    2014-05-01

    Human circulating endothelial progenitor cells isolated from peripheral blood generate in culture cells with features of endothelial cells named late-outgrowth endothelial colony-forming cells (ECFC). In adult blood, ECFC display a constant quantitative and qualitative decline during life span. Even after expansion, it is difficult to reach the cell dose required for cell therapy of vascular diseases, thus limiting the clinical use of these cells. Glycosaminoglycans (GAG) are components from the extracellular matrix (ECM) that are able to interact and potentiate heparin binding growth factor (HBGF) activities. According to these relevant biological properties of GAG, we designed a GAG mimetic having the capacity to increase the yield of ECFC production from blood and to improve functionality of their endothelial outgrowth. We demonstrate that the addition of [OTR(4131)] mimetic during the isolation process of ECFC from Cord Blood induces a 3 fold increase in the number of colonies. Moreover, addition of [OTR(4131)] to cell culture media improves adhesion, proliferation, migration and self-renewal of ECFC. We provide evidence showing that GAG mimetics may have great interest for cell therapy applied to vascular regeneration therapy and represent an alternative to exogenous growth factor treatments to optimize potential therapeutic properties of ECFC.

  15. [Effect of needling the mimetic muscle on recovery of mimetic function in the patient of spontaneous facial paralysis].

    PubMed

    Chen, Ri-Han; Chen, Ri-Li

    2008-11-01

    To observe therapeutic effects of different acupuncture methods for recovery of mimetic function in the patient of spontaneous facial paralysis. One hundred and thirty-four cases of facial paralysis were randomly divided into a mimetic muscle acupuncture group (mimetic muscle group, n = 79) and a routine acupoint group (n = 55). The mimetic muscle group were treated by encircling needling frontal belly of epicranial muscle, orbicular muscle of eye, orbicular muscle of mouth and buccinator muscle, and the routine acupoint group with acupuncture at Dicang (ST 4), Jiache (ST 6), Yangbai (GB 14), Sibai (ST 2), Cuanzhu (BL 2), etc. on the affected side. Their therapeutic effects were compared after they were treated for 2 courses. The effective rate and the good rate were 94.9% and 92.4% in the mimetic muscle group and 70.9% and 52.7% in the routine acupoint group, respectively, with a significant difference between the two groups (P < 0.05). The therapeutic effect of needling the mimetic muscle on spontaneous facial paralysis is superior to that of the routine acupuncture therapy.

  16. Expression of brain-derived neurotrophic factor and TrkB in the lateral line system of zebrafish during development.

    PubMed

    Germanà, A; Laurà, R; Montalbano, G; Guerrera, M C; Amato, V; Zichichi, R; Campo, S; Ciriaco, E; Vega, J A

    2010-07-01

    The neuromasts of the lateral line system are regarded as a model to study the mechanisms of hearing, deafness, and ototoxicity. The neurotrophins (NTs), especially brain-derived neurotrophic factor (BDNF), and its signaling receptor TrkB are involved in the development and maintenance of neuromasts. To know the period in which the BDNF/TrkB complex has more effects in the neuromast biology, the age-related changes were studied. Normal zebrafish from 10 to 180 days post-fertilization (dpf), as well as transgenic ET4 zebrafish 10 and 20 dpf, was analyzed using qRT-PCR, western blot, and immunohistochemistry. BDNF and TrkB mRNAs followed a parallel course, peaking at 20 dpf, and thereafter progressively decreased. Specific immunoreactivity for BDNF and TrkB was found co-localized in all hairy cells of neuromasts in 20 and 30 dpf; then, the number of immunoreactive cells decreased, and by 180 dpf BDNF remains restricted to a subpopulation of hairy cells, and TrkB to a few number of sensory and non-sensory cells. At all ages examined, TrkB immunoreactivity was detected in sensory ganglia innervating the neuromasts. The present results demonstrate that there is a parallel time-related decline in the expression of BDNF and TrkB in zebrafish. Also, the patterns of cell expression suggest that autocrine/paracrine mechanisms for this NT system might occur within the neuromasts. Because TrkB in lateral line ganglia did not vary with age, their neurons are potentially capable to respond to BDNF during the entire lifespan of zebrafish.

  17. Altered morphology of hippocampal dentate granule cell presynaptic and postsynaptic terminals following conditional deletion of TrkB.

    PubMed

    Danzer, Steve C; Kotloski, Robert J; Walter, Cynthia; Hughes, Maya; McNamara, James O

    2008-01-01

    Dentate granule cells play a critical role in the function of the entorhinal-hippocampal circuitry in health and disease. Dentate granule cells are situated to regulate the flow of information into the hippocampus, a structure required for normal learning and memory. Correspondingly, impaired granule cell function leads to memory deficits, and, interestingly, altered granule cell connectivity may contribute to the hyperexcitability of limbic epilepsy. It is important, therefore, to understand the molecular determinants of synaptic connectivity of these neurons. Brain-derived neurotrophic factor and its receptor TrkB are expressed at high levels in the dentate gyrus (DG) of the hippocampus, and are implicated in regulating neuronal development, neuronal plasticity, learning, and the development of epilepsy. Whether and how TrkB regulates granule cell structure, however, is incompletely understood. To begin to elucidate the role of TrkB in regulating granule cell morphology, here we examine conditional TrkB knockout mice crossed to mice expressing green fluorescent protein in subsets of dentate granule cells. In stratum lucidum, where granule cell mossy fiber axons project, the density of giant mossy fiber boutons was unchanged, suggesting similar output to CA3 pyramidal cell targets. However, filopodial extensions of giant boutons, which contact inhibitory interneurons, were increased in number in TrkB knockout mice relative to wildtype controls, predicting enhanced feedforward inhibition of CA3 pyramidal cells. In knockout animals, dentate granule cells possessed fewer primary dendrites and enlarged dendritic spines, indicative of disrupted excitatory synaptic input to the granule cells. Together, these findings demonstrate that TrkB is required for development and/or maintenance of normal synaptic connectivity of the granule cells, thereby implying an important role for TrkB in the function of the granule cells and hippocampal circuitry.

  18. Connexin43 mimetic peptide reduces vascular leak and retinal ganglion cell death following retinal ischaemia.

    PubMed

    Danesh-Meyer, Helen V; Kerr, Nathan M; Zhang, Jie; Eady, Elizabeth K; O'Carroll, Simon J; Nicholson, Louise F B; Johnson, Cameron S; Green, Colin R

    2012-02-01

    Connexin43 gap junction protein is expressed in astrocytes and the vascular endothelium in the central nervous system. It is upregulated following central nervous system injury and is recognized as playing an important role in modulating the extent of damage. Studies that have transiently blocked connexin43 in spinal cord injury and central nervous system epileptic models have reported neuronal rescue. The purpose of this study was to investigate neuronal rescue following retinal ischaemia-reperfusion by transiently blocking connexin43 activity using a connexin43 mimetic peptide. A further aim was to evaluate the effect of transiently blocking connexin43 on vascular permeability as this is known to increase following central nervous system ischaemia. Adult male Wistar rats were exposed to 60 min of retinal ischaemia. Treatment groups consisted of no treatment, connexin43 mimetic peptide and scrambled peptide. Retinas were then evaluated at 1-2, 4, 8 and 24 h, and 7 and 21 days post-ischaemia. Evans blue dye leak from retinal blood vessels was used to assess vascular leakage. Blood vessel integrity was examined using isolectin-B4 labelling. Connexin43 levels and astrocyte activation (glial fibrillary acidic protein) were assessed using immunohistochemistry and western blot analysis. Retinal whole mounts and retinal ganglion cell counts were used to quantify neurodegeneration. An in vitro cell culture model of endothelial cell ischaemia was used to assess the effect of connexin43 mimetic peptide on endothelial cell survival and connexin43 hemichannel opening using propidium iodide dye uptake. We found that retinal ischaemia-reperfusion induced significant vascular leakage and disruption at 1-2, 4 and 24 h following injury with a peak at 4 h. Connexin43 immunoreactivity was significantly increased at 1-2, 4, 8 and 24 h post ischaemia-reperfusion injury co-localizing with activated astrocytes, Muller cells and vascular endothelial cells. Connexin43 mimetic peptide

  19. Cerebral Response to Peripheral Challenge with a Viral Mimetic.

    PubMed

    Konat, Gregory

    2016-02-01

    It has been well established that peripheral inflammation resulting from microbial infections profoundly alters brain function. This review focuses on experimental systems that model cerebral effects of peripheral viral challenge. The most common models employ the induction of the acute phase response via intraperitoneal injection of a viral mimetic, polyinosinic-polycytidylic acid (PIC). The ensuing transient surge of blood-borne inflammatory mediators induces a "mirror" inflammatory response in the brain characterized by the upregulated expression of a plethora of genes encoding cytokines, chemokines and other inflammatory/stress proteins. These inflammatory mediators modify the activity of neuronal networks leading to a constellation of behavioral traits collectively categorized as the sickness behavior. Sickness behavior is an important protective response of the host that has evolved to enhance survival and limit the spread of infections within a population. However, a growing body of clinical data indicates that the activation of inflammatory pathways in the brain may constitute a serious comorbidity factor for neuropathological conditions. Such comorbidity has been demonstrated using the PIC paradigm in experimental models of Alzheimer's disease, prion disease and seizures. Also, prenatal or perinatal PIC challenge has been shown to disrupt normal cerebral development of the offspring resulting in phenotypes consistent with neuropsychiatric disorders, such as schizophrenia and autism. Remarkably, recent studies indicate that mild peripheral PIC challenge may be neuroprotective in stroke. Altogether, the PIC challenge paradigm represents a unique heuristic model to elucidate the immune-to-brain communication pathways and to explore preventive strategies for neuropathological disorders.

  20. Regulation of neurotrophin and trkA, trkB and trkC tyrosine kinase receptor messenger RNA expression in kindling.

    PubMed

    Bengzon, J; Kokaia, Z; Ernfors, P; Kokaia, M; Leanza, G; Nilsson, O G; Persson, H; Lindvall, O

    1993-03-01

    Levels of messenger RNA for nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3, and the tyrosine kinase receptors trkA, trkB and trkC have been studied using in situ hybridization in the rat brain 2 h and four weeks after kindling-induced seizures. Epileptiform activity evoked by hippocampal stimulation and exceeding 70 s lead to a concomitant and transient increase of brain- derived neurotrophic factor, nerve growth factor, trkB and trkC messenger RNA expression in dentate granule cells after both focal and generalized seizures. Brain-derived neurotrophic factor messenger RNA levels were also increased bilaterally in the CA1-CA3 regions, amygdala and the piriform, entorhinal, perirhinal, retrosplenial and temporal cortices after generalized seizures. The magnitude of the increases was similar throughout the development of kindling and in the fully kindled brain. No changes of trkA messenger RNA were observed. In amygdalar kindling, elevated brain-derived neurotrophic factor messenger RNA levels developed more rapidly in the amygdala-piriform cortex than after stimulation in the hippocampus but changes in the hippocampal formation were only seen in few animals. Intraventricular 6-hydroxydopamine or a bilateral fimbria-fornix lesion did not alter basal expression or seizure-evoked changes in messenger RNA levels for neurotrophins or trk receptors but increased the number of animals exhibiting elevated levels after the first stimulation, probably due to a prolongation of seizure activity. Both in sham-operated and fimbria-fornix-lesioned rats seizure activity caused a marked reduction of neurotrophin-3 messenger RNA levels in dentate granule cells. The results indicate that activation of the brain-derived neurotrophic factor gene, at least in dentate granule cells, is an "all-or-none" type of response and dependent on the duration but not the severity of seizures or the stage of kindling epileptogenesis. Changes in brain-derived neurotrophic

  1. Bcl-xL-inhibitory BH3 mimetics can induce a transient thrombocytopathy that undermines the hemostatic function of platelets.

    PubMed

    Schoenwaelder, Simone M; Jarman, Kate E; Gardiner, Elizabeth E; Hua, My; Qiao, Jianlin; White, Michael J; Josefsson, Emma C; Alwis, Imala; Ono, Akiko; Willcox, Abbey; Andrews, Robert K; Mason, Kylie D; Salem, Hatem H; Huang, David C S; Kile, Benjamin T; Roberts, Andrew W; Jackson, Shaun P

    2011-08-11

    BH3 mimetics are a new class of proapo-ptotic anticancer agents that have shown considerable promise in preclinical animal models and early-stage human trials. These agents act by inhibiting the pro-survival function of one or more Bcl-2-related proteins. Agents that inhibit Bcl-x(L) induce rapid platelet death that leads to thrombocytopenia; however, their impact on the function of residual circulating platelets remains unclear. In this study, we demonstrate that the BH3 mimetics, ABT-737 or ABT-263, induce a time- and dose-dependent decrease in platelet adhesive function that correlates with ectodomain shedding of the major platelet adhesion receptors, glycoprotein Ibα and glycoprotein VI, and functional down-regulation of integrin α(IIb)β(3). Analysis of platelets from mice treated with higher doses of BH3 mimetics revealed the presence of a subpopulation of circulating platelets undergoing cell death that have impaired activation responses to soluble agonists. Functional analysis of platelets by intravital microscopy revealed a time-dependent defect in platelet aggregation at sites of vascular injury that correlated with an increase in tail bleeding time. Overall, these studies demonstrate that Bcl-x(L)-inhibitory BH3 mimetics not only induce thrombocytopenia but also a transient thrombocytopathy that can undermine the hemostatic function of platelets.

  2. An overview on antidiabetic medicinal plants having insulin mimetic property.

    PubMed

    Patel, D K; Prasad, S K; Kumar, R; Hemalatha, S

    2012-04-01

    Diabetes mellitus is one of the common metabolic disorders acquiring around 2.8% of the world's population and is anticipated to cross 5.4% by the year 2025. Since long back herbal medicines have been the highly esteemed source of medicine therefore, they have become a growing part of modern, high-tech medicine. In view of the above aspects the present review provides profiles of plants (65 species) with hypoglycaemic properties, available through literature source from various database with proper categorization according to the parts used, mode of reduction in blood glucose (insulinomimetic or insulin secretagogues activity) and active phytoconstituents having insulin mimetics activity. From the review it was suggested that, plant showing hypoglycemic potential mainly belongs to the family Leguminoseae, Lamiaceae, Liliaceae, Cucurbitaceae, Asteraceae, Moraceae, Rosaceae and Araliaceae. The most active plants are Allium sativum, Gymnema sylvestre, Citrullus colocynthis, Trigonella foenum greacum, Momordica charantia and Ficus bengalensis. The review describes some new bioactive drugs and isolated compounds from plants such as roseoside, epigallocatechin gallate, beta-pyrazol-1-ylalanine, cinchonain Ib, leucocyandin 3-O-beta-d-galactosyl cellobioside, leucopelargonidin-3- O-alpha-L rhamnoside, glycyrrhetinic acid, dehydrotrametenolic acid, strictinin, isostrictinin, pedunculagin, epicatechin and christinin-A showing significant insulinomimetic and antidiabetic activity with more efficacy than conventional hypoglycaemic agents. Thus, from the review majorly, the antidiabetic activity of medicinal plants is attributed to the presence of polyphenols, flavonoids, terpenoids, coumarins and other constituents which show reduction in blood glucose levels. The review also discusses the management aspect of diabetes mellitus using these plants and their active principles.

  3. An overview on antidiabetic medicinal plants having insulin mimetic property

    PubMed Central

    Patel, DK; Prasad, SK; Kumar, R; Hemalatha, S

    2012-01-01

    Diabetes mellitus is one of the common metabolic disorders acquiring around 2.8% of the world's population and is anticipated to cross 5.4% by the year 2025. Since long back herbal medicines have been the highly esteemed source of medicine therefore, they have become a growing part of modern, high-tech medicine. In view of the above aspects the present review provides profiles of plants (65 species) with hypoglycaemic properties, available through literature source from various database with proper categorization according to the parts used, mode of reduction in blood glucose (insulinomimetic or insulin secretagogues activity) and active phytoconstituents having insulin mimetics activity. From the review it was suggested that, plant showing hypoglycemic potential mainly belongs to the family Leguminoseae, Lamiaceae, Liliaceae, Cucurbitaceae, Asteraceae, Moraceae, Rosaceae and Araliaceae. The most active plants are Allium sativum, Gymnema sylvestre, Citrullus colocynthis, Trigonella foenum greacum, Momordica charantia and Ficus bengalensis. The review describes some new bioactive drugs and isolated compounds from plants such as roseoside, epigallocatechin gallate, beta-pyrazol-1-ylalanine, cinchonain Ib, leucocyandin 3-O-beta-d-galactosyl cellobioside, leucopelargonidin-3- O-alpha-L rhamnoside, glycyrrhetinic acid, dehydrotrametenolic acid, strictinin, isostrictinin, pedunculagin, epicatechin and christinin-A showing significant insulinomimetic and antidiabetic activity with more efficacy than conventional hypoglycaemic agents. Thus, from the review majorly, the antidiabetic activity of medicinal plants is attributed to the presence of polyphenols, flavonoids, terpenoids, coumarins and other constituents which show reduction in blood glucose levels. The review also discusses the management aspect of diabetes mellitus using these plants and their active principles. PMID:23569923

  4. Energy restriction and potential energy restriction mimetics.

    PubMed

    Nikolai, Sibylle; Pallauf, Kathrin; Huebbe, Patricia; Rimbach, Gerald

    2015-12-01

    Energy restriction (ER; also known as caloric restriction) is the only nutritional intervention that has repeatedly been shown to increase lifespan in model organisms and may delay ageing in humans. In the present review we discuss current scientific literature on ER and its molecular, metabolic and hormonal effects. Moreover, criteria for the classification of substances that might induce positive ER-like changes without having to reduce energy intake are summarised. Additionally, the putative ER mimetics (ERM) 2-deoxy-d-glucose, metformin, rapamycin, resveratrol, spermidine and lipoic acid and their suggested molecular targets are discussed. While there are reports on these ERM candidates that describe lifespan extension in model organisms, data on longevity-inducing effects in higher organisms such as mice remain controversial or are missing. Furthermore, some of these candidates produce detrimental side effects such as immunosuppression or lactic acidosis, or have not been tested for safety in long-term studies. Up to now, there are no known ERM that could be recommended without limitations for use in humans.

  5. Emerging roles of ARHGAP33 in intracellular trafficking of TrkB and pathophysiology of neuropsychiatric disorders

    PubMed Central

    Nakazawa, Takanobu; Hashimoto, Ryota; Sakoori, Kazuto; Sugaya, Yuki; Tanimura, Asami; Hashimotodani, Yuki; Ohi, Kazutaka; Yamamori, Hidenaga; Yasuda, Yuka; Umeda-Yano, Satomi; Kiyama, Yuji; Konno, Kohtarou; Inoue, Takeshi; Yokoyama, Kazumasa; Inoue, Takafumi; Numata, Shusuke; Ohnuma, Tohru; Iwata, Nakao; Ozaki, Norio; Hashimoto, Hitoshi; Watanabe, Masahiko; Manabe, Toshiya; Yamamoto, Tadashi; Takeda, Masatoshi; Kano, Masanobu

    2016-01-01

    Intracellular trafficking of receptor proteins is essential for neurons to detect various extracellular factors during the formation and refinement of neural circuits. However, the precise mechanisms underlying the trafficking of neurotrophin receptors to synapses remain elusive. Here, we demonstrate that a brain-enriched sorting nexin, ARHGAP33, is a new type of regulator for the intracellular trafficking of TrkB, a high-affinity receptor for brain-derived neurotrophic factor. ARHGAP33 knockout (KO) mice exhibit reduced expression of synaptic TrkB, impaired spine development and neuropsychiatric disorder-related behavioural abnormalities. These deficits are rescued by specific pharmacological enhancement of TrkB signalling in ARHGAP33 KO mice. Mechanistically, ARHGAP33 interacts with SORT1 to cooperatively regulate TrkB trafficking. Human ARHGAP33 is associated with brain phenotypes and reduced SORT1 expression is found in patients with schizophrenia. We propose that ARHGAP33/SORT1-mediated TrkB trafficking is essential for synapse development and that the dysfunction of this mechanism may be a new molecular pathology of neuropsychiatric disorders. PMID:26839058

  6. Emerging roles of ARHGAP33 in intracellular trafficking of TrkB and pathophysiology of neuropsychiatric disorders.

    PubMed

    Nakazawa, Takanobu; Hashimoto, Ryota; Sakoori, Kazuto; Sugaya, Yuki; Tanimura, Asami; Hashimotodani, Yuki; Ohi, Kazutaka; Yamamori, Hidenaga; Yasuda, Yuka; Umeda-Yano, Satomi; Kiyama, Yuji; Konno, Kohtarou; Inoue, Takeshi; Yokoyama, Kazumasa; Inoue, Takafumi; Numata, Shusuke; Ohnuma, Tohru; Iwata, Nakao; Ozaki, Norio; Hashimoto, Hitoshi; Watanabe, Masahiko; Manabe, Toshiya; Yamamoto, Tadashi; Takeda, Masatoshi; Kano, Masanobu

    2016-02-03

    Intracellular trafficking of receptor proteins is essential for neurons to detect various extracellular factors during the formation and refinement of neural circuits. However, the precise mechanisms underlying the trafficking of neurotrophin receptors to synapses remain elusive. Here, we demonstrate that a brain-enriched sorting nexin, ARHGAP33, is a new type of regulator for the intracellular trafficking of TrkB, a high-affinity receptor for brain-derived neurotrophic factor. ARHGAP33 knockout (KO) mice exhibit reduced expression of synaptic TrkB, impaired spine development and neuropsychiatric disorder-related behavioural abnormalities. These deficits are rescued by specific pharmacological enhancement of TrkB signalling in ARHGAP33 KO mice. Mechanistically, ARHGAP33 interacts with SORT1 to cooperatively regulate TrkB trafficking. Human ARHGAP33 is associated with brain phenotypes and reduced SORT1 expression is found in patients with schizophrenia. We propose that ARHGAP33/SORT1-mediated TrkB trafficking is essential for synapse development and that the dysfunction of this mechanism may be a new molecular pathology of neuropsychiatric disorders.

  7. TrkB is necessary for pruning at the climbing fibre–Purkinje cell synapse in the developing murine cerebellum

    PubMed Central

    Johnson, Erin M; Craig, Ethan T; Yeh, Hermes H

    2007-01-01

    TrkB, the cognate receptor for brain-derived neurotrophic factor and neurotrophin-4, has been implicated in regulating synapse formation in the central nervous system. Here we asked whether TrkB plays a role in the maturation of the climbing fibre–Purkinje cell (CF–PC) synapse. In rodent cerebellum, Purkinje cells are initially innervated by multiple climbing fibres that are subsequently culled to assume the mature mono-innervated state, and whose contacts translocate from the soma to the dendrites. By employing transgenic mice hypomorphic or null for TrkB expression, our results indicated that perturbation of TrkB in the immature cerebellum resulted in ataxia, that Purkinje cells remained multiply innervated by climbing fibres beyond the normal developmental time frame, and that synaptic transmission at the parallel fibre–Purkinje cell synapse remained functionally unaltered. Mechanistically, we present evidence that attributes the persistence of multiple climbing fibre innervation to an obscured discrimination of relative strengths among competing climbing fibres. Soma-to-dendrite translocation of climbing fibre terminals was unaffected. Thus, TrkB regulates pruning but not translocation of nascent CF–PC synaptic contacts. PMID:17463037

  8. Dispersal of mimetic seeds of three species of Ormosia (Leguminosae)

    USGS Publications Warehouse

    Foster, M.S.; DeLay, L.S.

    1998-01-01

    Seeds with 'imitation arils' appear wholly or partially covered by pulp or aril but actually carry no fleshy material. The mimetic seed hypothesis to explain this phenomenon proposes a parasitic relationship in which birds are deceived into dispersing seeds that resemble bird-dispersed fruits, without receiving a nutrient reward. The hard-seed for grit hypothesis proposes a mutualistic relationship in which large, terrestrial birds swallow the exceptionally hard 'mimetic' seeds as grit for grinding the softer seeds on which they feed. They defecate, dispersing the seeds, and abrade the seed surface, enhancing germination. Any fruit mimicry is incidental. Fruiting trees of Ormosia spp. (Leguminosae: Papilionoideae) were observed to ascertain mechanisms of seed dispersal and the role of seemingly mimetic characteristics of the seeds in that dispersal. Seed predation and seed germination were also examined. Ormosia isthamensis and O. macrocalyx (but not O. bopiensis) deceived arboreally-foraging frugivorous birds into taking their mimetic seeds, although rates of seed dispersal were low. These results are consistent with the mimetic seed hypothesis. On the other hand, the rates of disappearance of seeds from the ground under the Ormosia trees, hardness of the seeds, and enhancement of germination with the abrasion of the seed coat are all consistent with the hard-seed for grit hypothesis.

  9. Tunicate-mimetic nanofibrous hydrogel adhesive with improved wet adhesion.

    PubMed

    Oh, Dongyeop X; Kim, Sangsik; Lee, Dohoon; Hwang, Dong Soo

    2015-07-01

    The main impediment to medical application of biomaterial-based adhesives is their poor wet adhesion strength due to hydration-induced softening and dissolution. To solve this problem, we mimicked the wound healing process found in tunicates, which use a nanofiber structure and pyrogallol group to heal any damage on its tunic under sea water. We fabricated a tunicate-mimetic hydrogel adhesive based on a chitin nanofiber/gallic acid (a pyrogallol acid) composite. The pyrogallol group-mediated cross-linking and the nanofibrous structures improved the dissolution resistance and cohesion strength of the hydrogel compared to the amorphous polymeric hydrogels in wet condition. The tunicate-mimetic adhesives showed higher adhesion strength between fully hydrated skin tissues than did fibrin glue and mussel-mimetic adhesives. The tunicate mimetic hydrogels were produced at low cost from recyclable and abundant raw materials. This tunicate-mimetic adhesive system is an example of how natural materials can be engineered for biomedical applications.

  10. Promotion of hair growth by newly synthesized ceramide mimetic compound.

    PubMed

    Park, Bu-Mahn; Bak, Soon-Sun; Shin, Kyung-Oh; Kim, Minhee; Kim, Daehwan; Jung, Sang-Hun; Jeong, Sekyoo; Sung, Young Kwan; Kim, Hyun Jung

    2017-09-09

    Based on the crucial roles of ceramides in skin barrier function, use of ceramides or their structural mimetic compounds, pseudoceramides, as cosmetic ingredients are getting more popular. While currently used pseudoceramides are intended to substitute the structural roles of ceramides in stratum corneum, development of bioactive pseudoceramides has been repeatedly reported. In this study, based on the potential involvement of sphingolipids in hair cycle regulation, we investigated the effects of newly synthesized pseudoceramide, bis-oleamido isopropyl alcohol (BOI), on hair growth using cultured human hair follicles and animal models. BOI treatment promoted hair growth in cultured human hair follicles ex vivo and induced earlier conversion of telogen into anagen. Although we did not find a significant enhancement of growth factor expression and follicular cell proliferation, BOI treatment resulted in an increased sphinganine and sphingosine contents as well as increased ceramides contents in cultured dermal papilla (DP) cells. Taken together, our data strongly suggest that biologically active pseudoceramide promotes hair growth by stimulating do novo synthesis of sphingolipids in DP cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Preclinical pharmacokinetic analysis of NOV-002, a glutathione disulfide mimetic.

    PubMed

    Uys, J D; Manevich, Y; Devane, L C; He, L; Garret, T E; Pazoles, C J; Tew, K D; Townsend, D M

    2010-09-01

    NOV-002 is a glutathione disulfide (GSSG) mimetic that is the subject of clinical investigation in oncology indications. GSSG is reduced by glutathione reductase (GR) to form glutathione (GSH), thereby maintaining redox homeostasis. The purpose of the study was to report the pharmacokinetic properties of NOV-002 and evaluate the effect that NOV-002 elicits in redox homeostasis. The pharmacokinetic analysis and tissue distribution of NOV-002 and GSH was evaluated in mice following a dose of 250 mg/kg, i.p. The redox potential and total protein thiol status was calculated. Here we show that NOV-002 is a substrate for GR and that GSH is a primary metabolite. Non-linear pharmacokinetic modeling predicted that the estimated absorption and elimination rate constants correspond to a half-life of approximately 13 min with an AUC of 1.18 μgh/mL, a C(max) of 2.16 μg/ml and a volume of distribution of 42.61 L/kg. In addition, measurement of the redox potential and total protein thiol status indicated the generation of a transient oxidative signal in the plasma compartment after administration of NOV-002. These results indicate that NOV-002 exerts kinetic and dynamic effects in mice consistent with the GSSG component as the active pharmacological constituent of the drug. A longer-lasting decrease in total plasma free thiol content was also seen, suggesting that the oxidative effect of the GSSG from NOV-002 was impacting redox homeostasis.

  12. Bio-mimetic optical sensor for structural deflection measurement

    NASA Astrophysics Data System (ADS)

    Frost, Susan A.; Wright, Cameron H. G.; Streeter, Robert W.; Khan, Md. A.; Barrett, Steven F.

    2014-03-01

    Reducing the environmental impact of aviation is a primary goal of NASA aeronautics research. One approach to achieve this goal is to build lighter weight aircraft, which presents complex challenges due to a corresponding increase in structural flexibility. Wing flexibility can adversely affect aircraft performance from the perspective of aerodynamic efficiency and safety. Knowledge of the wing position during flight can aid active control methods designed to mitigate problems due to increased wing flexibility. Current approaches to measuring wing deflection, including strain measurement devices, accelerometers, or GPS solutions, and new technologies such as fiber optic strain sensors, have limitations for their practical application to flexible aircraft control. Hence, it was proposed to use a bio-mimetic optical sensor based on the fly-eye to track wing deflection in real-time. The fly-eye sensor has several advantages over conventional sensors used for this application, including light weight, low power requirements, fast computation, and a small form factor. This paper reports on the fly-eye sensor development and its application to real-time wing deflection measurement.

  13. Apolipoprotein A-I Mimetic Peptides: Discordance Between In Vitro and In Vivo Properties-Brief Report.

    PubMed

    Ditiatkovski, Michael; Palsson, Jonatan; Chin-Dusting, Jaye; Remaley, Alan T; Sviridov, Dmitri

    2017-07-01

    Apolipoprotein A-I (apoA-I) mimetic peptides have antiatherogenic properties of high-density lipoprotein in vitro and have been shown to inhibit atherosclerosis in vivo. It is unclear, however, if each in vitro antiatherogenic property of these peptides translates to a corresponding activity in vivo, and if so, which of these contributes most to reduce atherosclerosis. The effect of 7 apoA-I mimetic peptides, which were developed to selectively reproduce a specific component of the antiatherogenic properties of apoA-I, on the development of atherosclerosis was investigated in apolipoprotein E-deficient mice fed a high-fat diet for 4 or 12 weeks. The peptides include those that selectively upregulate cholesterol efflux, or are anti-inflammatory, or have antioxidation properties. All the peptides studied effectively inhibited the in vivo development of atherosclerosis in this model to the same extent. However, none of the peptides had the same selective effect in vivo as they had exhibited in vitro. None of the tested peptides affected plasma lipoprotein profile; capacity of plasma to support cholesterol efflux was increased modestly and similarly for all peptides. There is a discordance between the selective in vitro and in vivo functional properties of apoA-I mimetic peptides, and the in vivo antiatherosclerotic effect of apoA-I-mimetic peptides is independent of their in vitro functional profile. Comparing the properties of apoA-I mimetic peptides in plasma rather than in the lipid-free state is better for predicting their in vivo effects on atherosclerosis. © 2017 American Heart Association, Inc.

  14. Deoxygedunin, a natural product with potent neurotrophic activity in mice.

    PubMed

    Jang, Sung-Wuk; Liu, Xia; Chan, Chi Bun; France, Stefan A; Sayeed, Iqbal; Tang, Wenxue; Lin, Xi; Xiao, Ge; Andero, Raul; Chang, Qiang; Ressler, Kerry J; Ye, Keqiang

    2010-07-13

    Gedunin, a family of natural products from the Indian neem tree, possess a variety of biological activities. Here we report the discovery of deoxygedunin, which activates the mouse TrkB receptor and its downstream signaling cascades. Deoxygedunin is orally available and activates TrkB in mouse brain in a BDNF-independent way. Strikingly, it prevents the degeneration of vestibular ganglion in BDNF -/- pups. Moreover, deoxygedunin robustly protects rat neurons from cell death in a TrkB-dependent manner. Further, administration of deoxygedunin into mice displays potent neuroprotective, anti-depressant and learning enhancement effects, all of which are mediated by the TrkB receptor. Hence, deoxygedunin imitates BDNF's biological activities through activating TrkB, providing a powerful therapeutic tool for treatment of various neurological diseases.

  15. Deoxygedunin, a Natural Product with Potent Neurotrophic Activity in Mice

    PubMed Central

    Jang, Sung-Wuk; Liu, Xia; Chan, Chi Bun; France, Stefan A.; Sayeed, Iqbal; Tang, Wenxue; Lin, Xi; Xiao, Ge; Andero, Raul; Chang, Qiang; Ressler, Kerry J.; Ye, Keqiang

    2010-01-01

    Gedunin, a family of natural products from the Indian neem tree, possess a variety of biological activities. Here we report the discovery of deoxygedunin, which activates the mouse TrkB receptor and its downstream signaling cascades. Deoxygedunin is orally available and activates TrkB in mouse brain in a BDNF-independent way. Strikingly, it prevents the degeneration of vestibular ganglion in BDNF −/− pups. Moreover, deoxygedunin robustly protects rat neurons from cell death in a TrkB-dependent manner. Further, administration of deoxygedunin into mice displays potent neuroprotective, anti-depressant and learning enhancement effects, all of which are mediated by the TrkB receptor. Hence, deoxygedunin imitates BDNF's biological activities through activating TrkB, providing a powerful therapeutic tool for treatment of various neurological diseases. PMID:20644624

  16. Increased Cx32 expression in spinal cord TrkB oligodendrocytes following peripheral axon injury.

    PubMed

    Coulibaly, Aminata P; Isaacson, Lori G

    2016-08-03

    Following injury to motor axons in the periphery, retrograde influences from the injury site lead to glial cell plasticity in the vicinity of the injured neurons. Following the transection of peripherally located preganglionic axons of the cervical sympathetic trunk (CST), a population of oligodendrocyte (OL) lineage cells expressing full length TrkB, the cognate receptor for brain derived neurotrophic factor (BDNF), is significantly increased in number in the spinal cord. Such robust plasticity in OL lineage cells in the spinal cord following peripheral axon transection led to the hypothesis that the gap junction communication protein connexin 32 (Cx32), which is specific to OL lineage cells, was influenced by the injury. Following CST transection, Cx32 expression in the spinal cord intermediolateral cell column (IML), the location of the parent cell bodies, was significantly increased. The increased Cx32 expression was localized specifically to TrkB OLs in the IML, rather than other cell types in the OL cell lineage, with the population of Cx32/TrkB cells increased by 59%. Cx32 expression in association with OPCs was significantly decreased at one week following the injury. The results of this study provide evidence that peripheral axon injury can differentially affect the gap junction protein expression in OL lineage cells in the adult rat spinal cord. We conclude that the retrograde influences originating from the peripheral injury site elicit dramatic changes in the CNS expression of Cx32, which in turn may mediate the plasticity of OL lineage cells observed in the spinal cord following peripheral axon injury.

  17. Characterization of Potent SMAC Mimetics that Sensitize Cancer Cells to TNF Family-Induced Apoptosis

    PubMed Central

    Welsh, Kate; Milutinovic, Snezana; Ardecky, Robert J.; Gonzalez-Lopez, Marcos; Ganji, Santhi Reddy; Finlay, Darren; Riedl, Stefan; Matsuzawa, Shu-ichi; Pinilla, Clemencia; Houghten, Richard; Vuori, Kristiina; Reed, John C.; Cosford, Nicholas D. P.

    2016-01-01

    Members of the Inhibitor of APoptosis (IAP) protein family suppress apoptosis within tumor cells, particularly in the context of immune cell-mediated killing by the tumor necrosis factor (TNF) superfamily cytokines. Most IAPs are opposed endogenously by the second mitochondrial activator of caspases (SMAC), which binds to selected baculovirus IAP repeat (BIR) domains of IAPs to displace interacting proteins. The development of SMAC mimetics as novel anticancer drugs has gained impetus, with several agents now in human clinical trials. To further understand the cellular mechanisms of SMAC mimetics, we focused on IAP family members cIAP1 and cIAP2, which are recruited to TNF receptor complexes where they support cell survival through NF-κB activation while suppressing apoptosis by preventing caspase activation. We established fluorescence polarization (FP) assays for the BIR2 and BIR3 domains of human cIAP1 and cIAP2 using fluorochrome-conjugated SMAC peptides as ligands. A library of SMAC mimetics was profiled using the FP assays to provide a unique structure activity relationship (SAR) analysis compared to previous assessments of binding to XIAP. Potent compounds displayed mean inhibitory binding constants (Ki) of 9 to 27 nM against the BIR3 domains of cIAP1 and cIAP2, respectively. Selected compounds were then characterized using cytotoxicity assays in which a cytokine-resistant human tumor cell line was sensitized to either TNF or lymphotoxin-α (LT-α). Cytotoxicity correlated closely with cIAP1 and cIAP2 BIR3 binding activity with the most potent compounds able to reduce cell viability by 50%. Further testing demonstrated that active compounds also inhibit RIP1 binding to BIR3 of cIAP1 and cIAP2 in vitro and reduce steady-state cIAP1 protein levels in cells. Altogether, these data inform the SAR for our SMAC mimetics with respect to cIAP1 and cIAP2, suggesting that these IAP family members play an important role in tumor cell resistance to cytotoxicity

  18. A human apolipoprotein E mimetic peptide reduces atherosclerosis in aged apolipoprotein E null mice

    PubMed Central

    Xu, Yanyong; Liu, Hongmei; Liu, Mengting; Li, Feifei; Liu, Liangchen; Du, Fen; Fan, Daping; Yu, Hong

    2016-01-01

    Apolipoprotein E (apoE) is well known as an antiatherogenic protein via regulating lipid metabolism and inflammation. We previously reported that a human apoE mimetic peptide, EpK, reduced atherosclerosis in apoE null (apoE-/-) mice through reducing inflammation without affecting plasma lipid levels. Here, we construct another human apoE mimetic peptide, named hEp, and investigate whether expression of hEp can reduce atherosclerotic lesion development in aged female apoE-/- mice with pre-existing lesions. We found that chemically synthesized hEp significantly decreased cholesterol accumulation induced by oxidized low density lipoprotein and the expression of inflammatory cytokines TNFα and IL-6 induced by lipopolysaccharide in macrophages. In an in vivo study, Lv-hEp-GFP lentiviruses were intravenously injected into 9 month-old apoE-/- mice. Mice were then fed a chow diet for 18 weeks. Results showed that in comparison to the Lv-GFP lentivirus injection (Lv-GFP) group, Lv-hEp-GFP lentivirus injection achieved hepatic hEp expression and secretion in apoE-/- mice. It was observed that hEp expression significantly reduced plasma VLDL and LDL cholesterol levels and decreased aortic atherosclerotic lesions. This was accompanied by an increase of LDL receptor expression and a reduction of TNFα and IL-6 mRNA levels in the liver. Moreover, expression of hEp increased plasma paraoxonase-1 activity and decreased plasma myeloperoxidase activity and serum amyloid A levels. Our study provides evidence that hEp may be developed as a promising therapeutic apoE mimetic peptide for atherosclerosis-related cardiovascular diseases through its induction of plasma VLDL/LDL cholesterol clearance as well as its anti-oxidative and anti-inflammatory activities. PMID:27648138

  19. Efficient synthesis of a multi-substituted diphenylmethane skeleton as a steroid mimetic.

    PubMed

    Misawa, Takashi; Tanaka, Katsuya; Demizu, Yosuke; Kurihara, Masaaki

    2017-03-24

    Steroids are important components of cell membranes and are involved in several physiological functions. A diphenylmethane (DPM) skeleton has recently been suggested to act as a mimetic of the steroid skeleton. However, difficulties are associated with efficiently introducing different substituents between two phenyl rings of the DPM skeleton, and, thus, further structural development based on the DPM skeleton has been limited. We herein developed an efficient synthetic method for introducing different substituents into two phenyl rings of the DPM skeleton. We also synthesized DPM-based estrogen receptor (ER) modulators using our synthetic method and evaluated their ER transcriptional activities.

  20. Discovery of HIV fusion inhibitors targeting gp41 using a comprehensive α-helix mimetic library

    PubMed Central

    Whitby, Landon R.; Boyle, Kristopher E.; Cai, Lifeng; Yu, Xiaoqian; Gochin, Miriam; Boger, Dale L.

    2012-01-01

    The evaluation of a comprehensive α-helix mimetic library for binding the gp41 NHR hydrophobic pocket recognizing an intramolecular CHR α-helix provided a detailed depiction of structural features required for binding and led to the discovery of small molecule inhibitors (Ki 0.6–1.3 µM) that not only match or exceed the potency of those disclosed over the past decade, but that also exhibit effective activity in a cell–cell fusion assay (IC50 5–8 µM). PMID:22424973

  1. BDNF, via truncated TrkB receptor, modulates GlyT1 and GlyT2 in astrocytes.

    PubMed

    Aroeira, Rita I; Sebastião, Ana M; Valente, Cláudia A

    2015-12-01

    Glycine transporters (GlyT), GlyT1 and GlyT2, are responsible for the termination of glycine-mediated synaptic activity through removal of neurotransmitter from synaptic cleft. Brain-derived neurotrophic factor (BDNF) activates its high affinity tropomyosin-related kinase (Trk) receptors, namely TrkB, which includes full length (TrkB-FL) and truncated (TrkB-T) isoforms. In this article we evaluated the influence of BDNF upon the activity of glycine transporters in astrocytes. We report that BDNF decreases GlyT1- and GlyT2- mediated [(3) H]glycine transport in primary cultures of astrocytes from rat cerebral cortex. BDNF decreased Vmax but not Km values of transport, which suggests that BDNF induces transporter internalization. Accordingly, dynasore, an inhibitor of dynamin/clathrin-dependent endocytosis, prevented the influence of BDNF upon GlyT-mediated transport. While quantifying mRNA and protein levels, we detected a predominance of truncated isoforms over the TrkB-FL receptor. The effect of BDNF was not abolished by specific inhibitors of PLCγ, PI3K and MAPK, indicating that it did not occur through TrkB-FL canonical pathways. However, BDNF action was lost in the presence of a Rho family-specific blocker (toxin B), a signaling pathway that has been associated to TrkB-T1. Furthermore, the effect of BDNF was abolished upon TrkB-T knockdown in astrocytes by RNA interference. Immunofluorescence assays confirmed an increased GlyT expression in endosomes upon BDNF incubation, which was prevented in the presence of either dynasore or toxin B. We conclude that BDNF, acting on TrkB-T1 receptors, inhibits glycine uptake in astrocytes by promoting GlyT internalization through a Rho-GTPase activity dependent mechanism. © 2015 Wiley Periodicals, Inc.

  2. Cerebral Response to Peripheral Challenge with a Viral Mimetic

    PubMed Central

    Konat, Gregory

    2015-01-01

    It has been well established that peripheral inflammation resulting from microbial infections profoundly alters brain function. This review focuses on experimental systems that model cerebral effects of peripheral viral challenge. The most common models employ the induction of the acute phase response (APR) via intraperitoneal injection of a viral mimetic, polyinosinic-polycytidylic acid (PIC). The ensuing transient surge of blood-borne inflammatory mediators induces a “mirror” inflammatory response in the brain characterized by the upregulated expression of a plethora of genes encoding cytokines, chemokines and other inflammatory/stress proteins. These inflammatory mediators modify the activity of neuronal networks leading to a constellation of behavioral traits collectively categorized as the sickness behavior. Sickness behavior is an important protective response of the host that has evolved to enhance survival and limit the spread of infections within a population. However, a growing body of clinical data indicates that the activation of inflammatory pathways in the brain may constitute a serious comorbidity factor for neuropathological conditions. Such comorbidity has been demonstrated using the PIC paradigm in experimental models of Alzheimer's disease, prion disease and seizures. Also, prenatal or perinatal PIC challenge has been shown to disrupt normal cerebral development of the offspring resulting in phenotypes consistent with neuropsychiatric disorders, such as schizophrenia and autism. Remarkably, recent studies indicate that mild peripheral PIC challenge may be neuroprotective in stroke. Altogether, the PIC challenge paradigm represents a unique heuristic model to elucidate the immune-to-brain communication pathways and to explore preventive strategies for neuropathological disorders. PMID:26526143

  3. Differential role of RIP1 in Smac mimetic-mediated chemosensitization of neuroblastoma cells

    PubMed Central

    Czaplinski, Sebastian; Abhari, Behnaz Ahangarian; Torkov, Alica; SeggewiΔ, Dominik; Hugle, Manuela; Fulda, Simone

    2015-01-01

    We explored the potential of Smac mimetics, which antagonize Inhibitor of Apoptosis (IAP) proteins, for chemosensitization of neuroblastoma (NB). Here, we report that Smac mimetics, e.g. BV6, prime NB cells for chemotherapeutics including the topoisomerase II inhibitor doxorubicin (DOX) and vinca alkaloids such as Vincristine (VCR), Vinblastine (VBL) and Vinorelbine (VNR). Additionally, BV6 acts in concert with DOX or VCR to suppress long-term clonogenic growth. While BV6 causes rapid downregulation of cellular IAP (cIAP)1 protein and nuclear factor-kappaB (NF-κB) activation, DOX/BV6- or VCR/BV6-induced apoptosis occurs independently of NF-κB or TNFα signaling, since overexpression of dominant-negative IκBα superrepressor or the Tumor Necrosis Factor (TNF)α-blocking antibody Enbrel fail to block cell death. Mechanistic studies reveal that Receptor-interacting protein (RIP)1 is required for DOX/BV6-, but not for VCR/BV6-induced apoptosis, since transient or stable knockdown of RIP1 or the pharmacological RIP1 inhibitor necrostatin-1 significantly reduce apoptosis. By comparison, VCR/BV6-mediated apoptosis critically depends on the mitochondrial pathway. VCR/BV6 cotreatment causes phosphorylation of BCL-2 during mitotic arrest, enhanced activation of BAX and BAK and loss of mitochondrial membrane potential (MMP). Additionally, overexpression of BCL-2 profoundly suppresses VCR/BV6-induced apoptosis. Thus, BV6 sensitizes NB cells to chemotherapy-induced apoptosis via distinct initial signaling mechanisms depending on the chemotherapeutic drug. These findings provide novel mechanistic insights into Smac mimetic-mediated chemosensitization of NB. PMID:26575016

  4. A New Aspect of the TrkB Signaling Pathway in Neural Plasticity

    PubMed Central

    Ohira, K; Hayashi, M

    2009-01-01

    In the central nervous system (CNS), the expression of molecules is strictly regulated during development. Control of the spatiotemporal expression of molecules is a mechanism not only to construct the functional neuronal network but also to adjust the network in response to new information from outside of the individual, i.e., through learning and memory. Among the functional molecules in the CNS, one of the best-studied groups is the neurotrophins, which are nerve growth factor (NGF)-related gene family molecules. Neurotrophins include NGF, brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), and NT-4/5 in the mammal. Among neurotrophins and their receptors, BDNF and tropomyosin-related kinases B (TrkB) are enriched in the CNS. In the CNS, the BDNF-TrkB signaling pathway fulfills a wide variety of functions throughout life, such as cell survival, migration, outgrowth of axons and dendrites, synaptogenesis, synaptic transmission, and remodeling of synapses. Although the same ligand and receptor, BDNF and TrkB, act in these various developmental events, we do not yet understand what kind of mechanism provokes the functional multiplicity of the BDNF-TrkB signaling pathway. In this review, we discuss the mechanism that elicits the variety of functions performed by the BDNF-TrkB signaling pathway in the CNS as a tool of pharmacological therapy. PMID:20514207

  5. A new aspect of the TrkB signaling pathway in neural plasticity.

    PubMed

    Ohira, K; Hayashi, M

    2009-12-01

    In the central nervous system (CNS), the expression of molecules is strictly regulated during development. Control of the spatiotemporal expression of molecules is a mechanism not only to construct the functional neuronal network but also to adjust the network in response to new information from outside of the individual, i.e., through learning and memory. Among the functional molecules in the CNS, one of the best-studied groups is the neurotrophins, which are nerve growth factor (NGF)-related gene family molecules. Neurotrophins include NGF, brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), and NT-4/5 in the mammal. Among neurotrophins and their receptors, BDNF and tropomyosin-related kinases B (TrkB) are enriched in the CNS. In the CNS, the BDNF-TrkB signaling pathway fulfills a wide variety of functions throughout life, such as cell survival, migration, outgrowth of axons and dendrites, synaptogenesis, synaptic transmission, and remodeling of synapses. Although the same ligand and receptor, BDNF and TrkB, act in these various developmental events, we do not yet understand what kind of mechanism provokes the functional multiplicity of the BDNF-TrkB signaling pathway. In this review, we discuss the mechanism that elicits the variety of functions performed by the BDNF-TrkB signaling pathway in the CNS as a tool of pharmacological therapy.

  6. Enzyme-mimetic model compounds: conformational analysis and far-IR study of Cu(TAAB)2+.

    PubMed

    Weinberger, P; Schamschule, R; Parusel, A B; Köhler, G; Linert, W

    2000-04-01

    Many enzymes occurring in nature like superoxide dismutase are systems rather too big to be accessible for vibrational and quantum chemical investigations. Thus, enzyme-mimetic model compounds consisting of a biological active metal centre surrounded by a macrocyclic ligand are used to shed light on binding properties of the active metal centre. Far- and mid-range IR spectroscopic investigations and a conformational analysis with the semi-empirical ZINDO/1 method of superoxide dismutase-mimetic complex Cu[TAAB]2+ are performed (TAAB = [b,f,j,n][1,5,9,13]tetra-aza-cyclohexadecine (tetra-anhydroamino benzaldehyde)). A distorted tetrahedral copper(II) centre with slightly twisted phenyl subunits is determined as the most stable conformation. Calculated mid- and far-IR spectra are in good agreement with the experimental data and confirm the proposed structure. A harmonic normal-coordinate analysis is used to assign the vibrational modes of the observed spectra.

  7. Functional and pharmacological characterization of a VEGF mimetic peptide on reparative angiogenesis.

    PubMed

    Finetti, Federica; Basile, Anna; Capasso, Domenica; Di Gaetano, Sonia; Di Stasi, Rossella; Pascale, Maria; Turco, Caterina Maria; Ziche, Marina; Morbidelli, Lucia; D'Andrea, Luca Domenico

    2012-08-01

    Vascular endothelial growth factor (VEGF) is the main regulator of physiological and pathological angiogenesis. Low molecular weight molecules able to stimulate angiogenesis have interesting medical application for example in regenerative medicine, but at present none has reached the clinic. We reported that a VEGF mimetic helical peptide, QK, designed on the VEGF helix sequence 17-25, is able to bind and activate the VEGF receptors, producing angiogenesis. In this study we evaluate the pharmacological properties of peptide QK with the aim to propose it as a VEGF-mimetic drug to be employed in reparative angiogenesis. We show that the peptide QK is able to recapitulate all the biological activities of VEGF in vivo and on endothelial cells. In experiments evaluating sprouting from aortic ring and vessel formation in an in vivo angiogenesis model, the peptide QK showed biological effects comparable with VEGF. At endothelial level, the peptide up-regulates VEGF receptor expression, activates intracellular pathways depending on VEGFR2, and consistently it induces endothelial cell proliferation, survival and migration. When added to angiogenic factors (VEGF and/or FGF-2), QK produces an improved biological action, which resulted in reduced apoptosis and accelerated in vitro wound healing. The VEGF-like activity of the short peptide QK, characterized by lower cost of production and easier handling compared to the native glycoprotein, suggests that it is an attractive candidate to be further developed for application in therapeutic angiogenesis.

  8. A BH3 Mimetic for Killing Cancer Cells.

    PubMed

    Green, Douglas R

    2016-06-16

    Venetoclax is a BH3 mimetic approved for treating chronic lymphocytic leukemia. Cancer cells are resistant to apoptosis but "primed for death" by elevated BCL-2, which binds to pro-apoptotic proteins and holds them in check. Venetoclax releases this antagonism and is the first approved drug to target a protein-protein interaction.

  9. Bio-Mimetic Sensors Based on Molecularly Imprinted Membranes

    PubMed Central

    Algieri, Catia; Drioli, Enrico; Guzzo, Laura; Donato, Laura

    2014-01-01

    An important challenge for scientific research is the production of artificial systems able to mimic the recognition mechanisms occurring at the molecular level in living systems. A valid contribution in this direction resulted from the development of molecular imprinting. By means of this technology, selective molecular recognition sites are introduced in a polymer, thus conferring it bio-mimetic properties. The potential applications of these systems include affinity separations, medical diagnostics, drug delivery, catalysis, etc. Recently, bio-sensing systems using molecularly imprinted membranes, a special form of imprinted polymers, have received the attention of scientists in various fields. In these systems imprinted membranes are used as bio-mimetic recognition elements which are integrated with a transducer component. The direct and rapid determination of an interaction between the recognition element and the target analyte (template) was an encouraging factor for the development of such systems as alternatives to traditional bio-assay methods. Due to their high stability, sensitivity and specificity, bio-mimetic sensors-based membranes are used for environmental, food, and clinical uses. This review deals with the development of molecularly imprinted polymers and their different preparation methods. Referring to the last decades, the application of these membranes as bio-mimetic sensor devices will be also reported. PMID:25196110

  10. Bio-mimetic sensors based on molecularly imprinted membranes.

    PubMed

    Algieri, Catia; Drioli, Enrico; Guzzo, Laura; Donato, Laura

    2014-07-30

    An important challenge for scientific research is the production of artificial systems able to mimic the recognition mechanisms occurring at the molecular level in living systems. A valid contribution in this direction resulted from the development of molecular imprinting. By means of this technology, selective molecular recognition sites are introduced in a polymer, thus conferring it bio-mimetic properties. The potential applications of these systems include affinity separations, medical diagnostics, drug delivery, catalysis, etc. Recently, bio-sensing systems using molecularly imprinted membranes, a special form of imprinted polymers, have received the attention of scientists in various fields. In these systems imprinted membranes are used as bio-mimetic recognition elements which are integrated with a transducer component. The direct and rapid determination of an interaction between the recognition element and the target analyte (template) was an encouraging factor for the development of such systems as alternatives to traditional bio-assay methods. Due to their high stability, sensitivity and specificity, bio-mimetic sensors-based membranes are used for environmental, food, and clinical uses. This review deals with the development of molecularly imprinted polymers and their different preparation methods. Referring to the last decades, the application of these membranes as bio-mimetic sensor devices will be also reported.

  11. Dark energy oscillations in mimetic F (R ) gravity

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-08-01

    In this paper we address the problem of dark energy oscillations in the context of mimetic F (R ) gravity with potential. The issue of dark energy oscillations can be a problem in some models of ordinary F (R ) gravity, and a remedy that can make the oscillations milder is to introduce additional modifications in the functional form of the F (R ) gravity. As we demonstrate, the power-law modifications are not necessary in the mimetic F (R ) case, and by appropriately choosing the mimetic potential and the Lagrange multiplier, it is possible to make the oscillations almost vanish at the end of the matter domination era and during the late-time acceleration era. We examine the behavior of the dark energy equation of state parameter and of the total effective equation of state parameter as functions of the redshift, and we compare the resulting picture with the ordinary F (R ) gravity case. As we also show that the present day values of the dark energy equation of state parameter and of the total effective equation of state parameter are in better agreement with the observational data, in comparison to the ordinary F (R ) gravity case. Finally, we study the evolution of the growth factor as a function of the redshift for all the mimetic models we use.

  12. Cholesterol depletion blocks redistribution of lipid raft components and insulin-mimetic signaling by glimepiride and phosphoinositolglycans in rat adipocytes.

    PubMed Central

    Müller, Gunter; Hanekop, Nils; Wied, Susanne; Frick, Wendelin

    2002-01-01

    Glycosylphosphatidylinositol-anchored plasma membrane (GPI) proteins, such as Gce1, the dually acylated nonreceptor tyrosine kinases (NRTKs), such as pp59(Lyn), and the membrane protein, caveolin, together with cholesterol are typical components of detergent/carbonate-insoluble glycolipid-enriched raft domains (DIGs) in the plasma membrane of most eucaryotes. Previous studies demonstrated the dissociation from caveolin and concomitant redistribution from DIGs of Gce1 and pp59(Lyn) in rat adipocytes in response to four different insulin-mimetic stimuli, glimepiride, phosphoinositolglycans, caveolin-binding domain peptide, and trypsin/NaCl-treatment. We now characterized the structural basis for this dynamic of DIG components. MATERIALS AND METHODS: Carbonate extracts from purified plasma membranes of basal and stimulated adipocytes were analyzed by high-resolution sucrose gradient centrifugation. RESULTS: This process revealed the existence of two distinct species of detergent/carbonate-insoluble complexes floating at higher buoyant density and harboring lower amounts of cholesterol, caveolin, GPI proteins, and NRTKs (lcDIGs) compared to typical DIGs of high cholesterol content (hcDIGs). The four insulin-mimetic stimuli decreased by 40-70% and increased by 2.5- to 5-fold the amounts of GPI proteins and NRTKs at hcDIGs and lcDIGs, respectively. Cholesterol depletion of adipocytes per se by incubation with methyl-beta-cyclodextrin or cholesterol oxidase also caused translocation of GPI proteins and NRTKs from hcDIGs to lcDIGs and their release from caveolin in reversible fashion without concomitant induction of insulin-mimetic signaling. Cholesterol depletion, however, reduced by 50-60% the stimulus-induced translocation as well as dissociation from hcDIGs-associated caveolin of GPI proteins and NRTKs, activation of NRTKs as well as insulin-mimetic signaling and metabolic action. In contrast, insulin-mimetic signaling induced by vanadium compounds was not

  13. Cellular hybridization for BDNF, trkB, and NGF mRNAs and BDNF-immunoreactivity in rat forebrain after pilocarpine-induced status epilepticus.

    PubMed

    Schmidt-Kastner, R; Humpel, C; Wetmore, C; Olson, L

    1996-01-01

    The messenger RNAs (mRNAs) for the neurotrophins, brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF), are upregulated during epileptic seizure activity, as visualized by in situ hybridization techniques. Neurotrophins might be protective against excitotoxic cell stress, and the upregulation during seizures might provide such cell protection. In this study, a high dose of pilocarpine (300 mg/kg) was used to induce long-lasting, limbic motor status epilepticus and a selective pattern of brain damage. The regulation of BDNF, trkB, and NGF mRNA was studied by in situ hybridization at 1, 3, 6, and 24 h after induction of limbic motor status epilepticus. BDNF immunoreactivity was examined with an anti-peptide antibody and the neuropathological process studied in parallel. BDNF mRNA increased in hippocampus, neocortex, piriform cortex, striatum, and thalamus with a maximum at 3-6 h. Hybridization levels increased earlier in the resistant granule and CA1 cells as compared to the vulnerable CA3 neurons. BDNF immunoreactivity was elevated in dentate gyrus at 3-6 h. trkB mRNA increased in the entire hippocampus. NGF mRNA in hippocampus appeared in dentate gyrus at 3-6 h and declined in hilar neurons at 6-24 h. Cell damage was found in the CA3 area, entire basal cortex, and layers II/III of neocortex. Endogenous neurotrophins are upregulated during status epilepticus caused by pilocarpine, which is related to the coupling between neuronal excitation and trophic factor expression. This upregulation of neurotrophic factors may serve endogenous protective effects; however, the excessive levels of neuronal hyperexcitation resulting from pilocarpine seizures lead to cell damage which cannot be prevented by endogenous neurotrophins.

  14. Human neural stem/progenitor cells derived from the olfactory epithelium express the TrkB receptor and migrate in response to BDNF.

    PubMed

    Ortiz-López, Leonardo; González-Olvera, Jorge Julio; Vega-Rivera, Nelly Maritza; García-Anaya, Maria; Carapia-Hernández, Ana Karen; Velázquez-Escobar, Julio César; Ramírez-Rodríguez, Gerardo Bernabé

    2017-07-04

    Neurogenesis constitutively occurs in the olfactory epithelium of mammals, including humans. The fact that new neurons in the adult olfactory epithelium derive from resident neural stem/progenitor cells suggests a potential use for these cells in studies of neural diseases, as well as in neuronal cell replacement therapies. In this regard, some studies have proposed that the human olfactory epithelium is a source of neural stem/progenitor cells for autologous transplantation. Although these potential applications are interesting, it is important to understand the cell biology and/or whether human neural stem/progenitor cells in the olfactory epithelium sense external signals, such as brain-derived neurotrophic factor (BDNF), that is also found in other pro-neurogenic microenvironments. BDNF plays a key role in several biological processes, including cell migration. Thus, we characterized human neural stem/progenitor cells derived from the olfactory epithelium (hNS/PCs-OE) and studied their in vitro migratory response to BDNF. In the present study, we determined that hNS/PCs-OE express the protein markers Nestin, Sox2, Ki67 and βIII-tubulin. Moreover, the doubling time of hNS/PCs-OE was approximately 38h. Additionally, we found that hNS/PCs-OE express the BDNF receptor TrkB, and pharmacological approaches showed that the BDNF-induced (40ng/ml) migration of differentiated hNS/PCs-OE was affected by the compound K252a, which prevents TrkB activation. This observation was accompanied by changes in the number of vinculin adhesion contacts. Our results suggest that hNS/PCs-OE exhibit a migratory response to BDNF, accompanied by the turnover of adhesion contacts. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  15. Mature brain-derived neurotrophic factor and its receptor TrkB are upregulated in human glioma tissues.

    PubMed

    Xiong, Jing; Zhou, L I; Lim, Yoon; Yang, Miao; Zhu, Yu-Hong; Li, Zhi-Wei; Fu, Deng-Li; Zhou, Xin-Fu

    2015-07-01

    There are two forms of brain-derived neurotrophic factor (BDNF), precursor of BDNF (proBDNF) and mature BDNF, which each exert opposing effects through two different transmembrane receptor signaling systems, consisting of p75 neurotrophin receptor (p75NTR) and tyrosine receptor kinase B (TrkB). Previous studies have demonstrated that proBDNF promotes cell death and inhibits the growth and migration of C6 glioma cells through p75NTR in vitro, while mature BDNF has opposite effects on C6 glioma cells. It is hypothesized that mature BDNF is essential in the development of malignancy in gliomas. However, histological data obtained in previous studies were unable distinguish mature BDNF from proBDNF due to the lack of specific antibodies. The present study investigated the expression of mature BDNF using a specific sheep monoclonal anti-mature BDNF antibody in 42 human glioma tissues of different grades and 10 control tissues. The correlation between mature BDNF and TrkB was analyzed. Mature BDNF expression was significantly increased in high-grade gliomas, and was positively correlated with the malignancy of the tumor and TrkB receptor expression. The present data have demonstrated that increased levels of mature BDNF contribute markedly to the development of malignancy of human gliomas through the primary BDNF receptor TrkB.

  16. Expression of brain-derived neurotrophic factor and TrkB receptor in the sudden infant death syndrome brainstem.

    PubMed

    Tang, Samantha; Machaalani, Rita; Waters, Karen A

    2012-01-15

    This study compared the expression of BDNF (proBDNF and rhBDNF forms) and its receptor TrkB, in the medulla of sudden infant death syndrome (SIDS) infants and infants who died from known causes (non-SIDS). This study also evaluated these markers in association with SIDS clinical risk factors including, sleep position, cigarette smoke exposure and gender. Brainstem tissue was immunohistochemically stained and quantitative analyses were made for eight nuclei of the caudal and rostral medulla. Compared to non-SIDS, SIDS infants had lower rhBDNF in the caudal nucleus of the solitary tract and higher TrkB in the caudal dorsal motor nucleus of the vagus. Within the SIDS cohort, prone sleep position was associated with lower rhBDNF in the caudal arcuate nucleus, and cigarette smoke exposure was associated with lower rhBDNF and TrkB in the inferior olivary nucleus. Abnormal expression of BDNF and TrkB suggests that neuroprotective functions of the BDNF/TrkB system may be reduced in respiratory-related nuclei of SIDS infants.

  17. Selective Requirement for Maintenance of Synaptic Contacts onto Motoneurons by Target-Derived trkB Receptors.

    PubMed

    Zhu, Xiya; Ward, Patricia J; English, Arthur W

    2016-01-01

    Synaptic contacts onto motoneurons were studied in mice in which the gene for the trkB neurotrophin receptor was knocked out selectively in a subset of spinal motoneurons. The extent of contacts by structures immunoreactive for either of two different vesicular glutamate transporters (VGLUT1 and VGLUT2), the vesicular GABA transporter, or glutamic acid decarboxylase 67 (GAD67) with the somata of motoneurons, was studied in wild type and trkB knockout cells in tamoxifen treated male and female SLICK-trkB(-/-) mice. Selective knockout of the trkB gene resulted in a marked reduction in contacts made by VGLUT2- and GAD67-immunoreactive structures in both sexes and a significant reduction in contacts containing only glycine in male mice. No reduction was found for glycinergic contacts in female mice or for VGLUT1 immunoreactive contacts in either sex. Signaling through postsynaptic trkB receptors is considered to be an essential part of a cellular mechanism for maintaining the contacts of some, but not all, synaptic contacts onto motoneurons.

  18. Selective Requirement for Maintenance of Synaptic Contacts onto Motoneurons by Target-Derived trkB Receptors

    PubMed Central

    2016-01-01

    Synaptic contacts onto motoneurons were studied in mice in which the gene for the trkB neurotrophin receptor was knocked out selectively in a subset of spinal motoneurons. The extent of contacts by structures immunoreactive for either of two different vesicular glutamate transporters (VGLUT1 and VGLUT2), the vesicular GABA transporter, or glutamic acid decarboxylase 67 (GAD67) with the somata of motoneurons, was studied in wild type and trkB knockout cells in tamoxifen treated male and female SLICK-trkB−/− mice. Selective knockout of the trkB gene resulted in a marked reduction in contacts made by VGLUT2- and GAD67-immunoreactive structures in both sexes and a significant reduction in contacts containing only glycine in male mice. No reduction was found for glycinergic contacts in female mice or for VGLUT1 immunoreactive contacts in either sex. Signaling through postsynaptic trkB receptors is considered to be an essential part of a cellular mechanism for maintaining the contacts of some, but not all, synaptic contacts onto motoneurons. PMID:27433358

  19. The promise of apolipoprotein A-I mimetics.

    PubMed

    Mendez, Armando J

    2010-04-01

    Synthetic high-density lipoprotein (HDL) and apolipoprotein (apo) A-I mimetic peptides emulate many of the atheroprotective biological functions attributed to HDL and can modify atherosclerotic disease processes. Administration of these agents as HDL replacement or modifying therapy has tremendous potential of providing new treatments for cardiovascular disease. Progress in the understanding of these agents is discussed in this review. Prospective, observational, and interventional studies have convincingly demonstrated that elevated serum levels of high-density lipoprotein-cholesterol (HDL-C) are associated with reduced risk for coronary heart disease (CHD). Although traditional pharmacological agents have shown modest utility in raising HDL levels and reducing CHD risk, use of HDL and apo A-I mimetics provides novel therapies to not only increase HDL levels, but to also influence HDL functionality. Evidence developed over the last several years has identified a number of pathways affected by synthetic HDL and apoA-I mimetic peptides, including enhancing reverse cholesterol transport and reducing oxidation and inflammation that directly influence the progression and regression of atherosclerotic disease. Clinical trials of relatively short-term synthetic HDL infusion into patients with CHD demonstrate beneficial effects. Use of apo A-I mimetic peptides could potentially overcome some of the limitations associated with use of the intact apo. Studies to establish the most efficacious peptides, optimal dosing regimens, and routes of administration are needed. Use of apo A-I mimetic peptides shows great promise as a therapeutic modality for HDL replacement and enhancing HDL function in treatment of patients with CHD.

  20. Exercise-mimetic AICAR transiently benefits brain function.

    PubMed

    Guerrieri, Davide; van Praag, Henriette

    2015-07-30

    Exercise enhances learning and memory in animals and humans. The role of peripheral factors that may trigger the beneficial effects of running on brain function has been sparsely examined. In particular, it is unknown whether AMP-kinase (AMPK) activation in muscle can predict enhancement of brain plasticity. Here we compare the effects of running and administration of AMPK agonist 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR, 500 mg/kg), for 3, 7 or 14 days in one-month-old male C57BL/6J mice, on muscle AMPK signaling. At the time-points where we observed equivalent running- and AICAR-induced muscle pAMPK levels (7 and 14 days), cell proliferation, synaptic plasticity and gene expression, as well as markers of oxidative stress and inflammation in the dentate gyrus (DG) of the hippocampus and lateral entorhinal cortex (LEC) were evaluated. At the 7-day time-point, both regimens increased new DG cell number and brain-derived neurotrophic factor (BDNF) protein levels. Furthermore, microarray analysis of DG and LEC tissue showed a remarkable overlap between running and AICAR in the regulation of neuronal, mitochondrial and metabolism related gene classes. Interestingly, while similar outcomes for both treatments were stable over time in muscle, in the brain an inversion occurred at fourteen days. The compound no longer increased DG cell proliferation or neurotrophin levels, and upregulated expression of apoptotic genes and inflammatory cytokine interleukin-1β. Thus, an exercise mimetic that produces changes in muscle consistent with those of exercise does not have the same sustainable positive effects on the brain, indicating that only running consistently benefits brain function.

  1. Exercise-mimetic AICAR transiently benefits brain function

    PubMed Central

    Guerrieri, Davide; van Praag, Henriette

    2015-01-01

    Exercise enhances learning and memory in animals and humans. The role of peripheral factors that may trigger the beneficial effects of running on brain function has been sparsely examined. In particular, it is unknown whether AMP-kinase (AMPK) activation in muscle can predict enhancement of brain plasticity. Here we compare the effects of running and administration of AMPK agonist 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR, 500 mg/kg), for 3, 7 or 14 days in one-month-old male C57BL/6J mice, on muscle AMPK signaling. At the time-points where we observed equivalent running- and AICAR-induced muscle pAMPK levels (7 and 14 days), cell proliferation, synaptic plasticity and gene expression, as well as markers of oxidative stress and inflammation in the dentate gyrus (DG) of the hippocampus and lateral entorhinal cortex (LEC) were evaluated. At the 7-day time-point, both regimens increased new DG cell number and brain-derived neurotrophic factor (BDNF) protein levels. Furthermore, microarray analysis of DG and LEC tissue showed a remarkable overlap between running and AICAR in the regulation of neuronal, mitochondrial and metabolism related gene classes. Interestingly, while similar outcomes for both treatments were stable over time in muscle, in the brain an inversion occurred at fourteen days. The compound no longer increased DG cell proliferation or neurotrophin levels, and upregulated expression of apoptotic genes and inflammatory cytokine interleukin-1β. Thus, an exercise mimetic that produces changes in muscle consistent with those of exercise does not have the same sustainable positive effects on the brain, indicating that only running consistently benefits brain function. PMID:26286955

  2. Preclinical Pharmacokinetic Analysis of NOV-002, a Glutathione Disulfide Mimetic

    PubMed Central

    Uys, Joachim D.; Manevich, Yefim; DeVane, Lindsay C.; He, Lin; Garret, Tracy E.; Pazoles, Christopher J.; Tew, Kenneth D.; Townsend, Danyelle M.

    2010-01-01

    Summary NOV-002 is a glutathione disulfide (GSSG) mimetic that is in Phase III clinical trials for the treatment of advanced non-small cell lung cancer and other oncology indications. GSSG is reduced by glutathione reductase (GR) to form glutathione (GSH), thereby maintaining redox homeostasis. The purpose of the study was to report the pharmacokinetic properties of NOV-002 and evaluate the effect that NOV-002 elicits in redox homeostasis. The pharmacokinetic analysis and tissue distribution of NOV-002 and GSH was evaluated in mice following a dose of 250 mg/kg, i.p. The redox potential and total protein thiol status was calculated. Here we show that NOV-002 is a substrate for GR and that GSH is a primary metabolite. Nonlinear pharmacokinetic modeling predicted that the estimated absorption and elimination rate constants correspond to a half-life of ~13 mins with an AUC of 1.18 μg.h/ml, a Cmax of 2.16 μg/ml and a volume of distribution of 42.61 L/kg. In addition, measurement of the redox potential and total protein thiol status indicated the generation of a transient oxidative signal in the plasma compartment after administration of NOV-002. These results indicate that NOV-002 exerts kinetic and dynamic effects in mice consistent with the GSSG component as the active pharmacological constituent of the drug. A longer-lasting decrease in total plasma free thiol content was also seen, suggesting that the oxidative effect of the GSSG from NOV-002 was impacting redox homeostasis. PMID:20359856

  3. Fibronectin Matrix Mimetics Promote Full-Thickness Wound Repair in Diabetic Mice

    PubMed Central

    Roy, Daniel C.; Mooney, Nancie A.; Raeman, Carol H.; Dalecki, Diane

    2013-01-01

    During tissue repair, fibronectin is converted from a soluble, inactive form into biologically active extracellular matrix (ECM) fibrils through a cell-dependent process. ECM fibronectin promotes numerous cell processes that are critical to tissue repair and regulates the assembly of other proteins into the matrix. Nonhealing wounds show reduced levels of ECM fibronectin. To functionally mimic ECM fibronectin, a series of fibronectin matrix mimetics was developed by directly coupling the matricryptic, heparin-binding fragment of the first type III repeat of fibronectin (FNIII1H) to various sequences from the integrin-binding domain (FNIII8–10). The recombinant proteins were produced as glutathione-S-transferase (GST)-tagged fusion proteins for ease of production and purification. Full-thickness, excisional wounds were produced in genetically diabetic mice, and fibronectin matrix mimetics were applied directly to the wounds. A significant enhancement of wound closure was observed by day 9 in response to GST/III1H,8–10 versus GST-treated controls (73.9%±4.1% vs. 58.1%±4.7% closure, respectively). Two weeks after injury, fibronectin matrix mimetic-treated wounds had developed a multi-layered epithelium that completely covered the wound space. Furthermore, significant increases in granulation tissue thickness were observed in response to treatment with GST/III1H,8–10 (4.05±0.93-fold), GST/III1H,8,10 (2.91±0.49-fold), or GST/III1H,8RGD (3.55±0.59-fold) compared with GST controls, and was accompanied by dense collagen deposition, the presence of myofibroblasts, and functional vasculature. Thus, the recombinant fibronectin matrix analogs normalized the impairment in repair observed in this chronic wound model and may provide a new approach to accelerate the healing of diabetic wounds. PMID:23808793

  4. Aggrecan-mimetic, glycosaminoglycan-containing nanoparticles for growth factor stabilization and delivery.

    PubMed

    Place, Laura W; Sekyi, Maria; Kipper, Matt J

    2014-02-10

    The direct delivery of growth factors to sites of tissue healing is complicated by their relative instability. In many tissues, the glycosaminoglycan (GAG) side chains of proteoglycans like aggrecan stabilize growth factors in the pericellular and extracellular space, creating a local reservoir that can be accessed during a wound healing response. GAGs also regulate growth factor-receptor interactions at the cell surface. Here we report the development of nanoparticles for growth factor delivery that mimic the size, GAG composition, and growth factor binding and stabilization of aggrecan. The aggrecan-mimetic nanoparticles are easy to assemble, and their structure and composition can be readily tuned to alter their physical and biological properties. We use basic fibroblast growth factor (FGF-2) as a model heparin-binding growth factor, demonstrating that aggrecan-mimetic nanoparticles can preserve its activity for more than three weeks. We evaluate FGF-2 activity by measuring both the proliferation and metabolic activity of bone marrow stromal cells to demonstrate that chondroitin sulfate-based aggrecan mimics are as effective as aggrecan, and heparin-based aggrecan mimics are superior to aggrecan as delivery vehicles for FGF-2.

  5. Effects of TrkB agonist 7,8-dihydroxyflavone on sensory gating deficits in mice after administration of methamphetamine.

    PubMed

    Ren, Qian; Zhang, Ji-Chun; Fujita, Yuko; Ma, Min; Wu, Jin; Hashimoto, Kenji

    2013-05-01

    Several lines of evidence suggest that the brain-derived neurotrophic factor (BDNF)-tropomyosin-related kinase B (TrkB) signaling pathway plays a role in behavioral abnormalities observed after administration of psychostimulants, such as methamphetamine (METH). This study was undertaken to examine whether the potent TrkB agonist, 7,8-dihydroxyflavone (7,8-DHF) could improve prepulse inhibition (PPI) deficits in mice seen after a single dose of METH. Treatment with 7,8-DHF (3.0, 10 or 30 mg/kg) improved PPI deficits in mice associated with exposure to METH (3.0 mg/kg), in a dose dependent manner. Furthermore, co-administration of ANA-12 (0.5 mg/kg), a TrkB antagonist, significantly blocked the effects of 7,8-DHF (30 mg/kg) on METH-induced PPI deficits. In contrast, administration of 5,7-dihydroxyflavone (5,7-DHF: 30 mg/kg), an inactive TrkB ligand, did not affect METH-induced PPI deficits in mice. An in vivo microdialysis study in conscious mice showed that 7,8-DHF (30 mg/kg) significantly attenuated increased dopamine release in the striatum, after METH administration (3 mg/kg). This study suggests that 7,8-DHF can improve PPI deficits in these mice, through the inhibition of METH-induced dopamine release. Therefore, it is likely that TrkB agonists, such as 7,8-DHF, may constitute a novel class of therapeutic drugs for neuropsychiatric diseases such as METH-use disorder and schizophrenia.

  6. Antibodies Elicited by Multiple Envelope Glycoprotein Immunogens in Primates Neutralize Primary Human Immunodeficiency Viruses (HIV-1) Sensitized by CD4-Mimetic Compounds

    PubMed Central

    Madani, Navid; Princiotto, Amy M.; Easterhoff, David; Bradley, Todd; Luo, Kan; Williams, Wilton B.; Liao, Hua-Xin; Moody, M. Anthony; Phad, Ganesh E.; Vázquez Bernat, Néstor; Melillo, Bruno; Santra, Sampa; Smith, Amos B.; Karlsson Hedestam, Gunilla B.; Haynes, Barton

    2016-01-01

    ABSTRACT The human immunodeficiency virus (HIV-1) envelope glycoproteins (Env) mediate virus entry through a series of complex conformational changes triggered by binding to the receptors CD4 and CCR5/CXCR4. Broadly neutralizing antibodies that recognize conserved Env epitopes are thought to be an important component of a protective immune response. However, to date, HIV-1 Env immunogens that elicit broadly neutralizing antibodies have not been identified, creating hurdles for vaccine development. Small-molecule CD4-mimetic compounds engage the CD4-binding pocket on the gp120 exterior Env and induce Env conformations that are highly sensitive to neutralization by antibodies, including antibodies directed against the conserved Env region that interacts with CCR5/CXCR4. Here, we show that CD4-mimetic compounds sensitize primary HIV-1 to neutralization by antibodies that can be elicited in monkeys and humans within 6 months by several Env vaccine candidates, including gp120 monomers. Monoclonal antibodies directed against the gp120 V2 and V3 variable regions were isolated from the immunized monkeys and humans; these monoclonal antibodies neutralized a primary HIV-1 only when the virus was sensitized by a CD4-mimetic compound. Thus, in addition to their direct antiviral effect, CD4-mimetic compounds dramatically enhance the HIV-1-neutralizing activity of antibodies that can be elicited with currently available immunogens. Used as components of microbicides, the CD4-mimetic compounds might increase the protective efficacy of HIV-1 vaccines. IMPORTANCE Preventing HIV-1 transmission is a high priority for global health. Eliciting antibodies that can neutralize transmitted strains of HIV-1 is difficult, creating problems for the development of an effective vaccine. We found that small-molecule CD4-mimetic compounds sensitize HIV-1 to antibodies that can be elicited in vaccinated humans and monkeys. These results suggest an approach to prevent HIV-1 sexual transmission in

  7. Targeted taste cell-specific overexpression of brain-derived neurotrophic factor in adult taste buds elevates phosphorylated TrkB protein levels in taste cells, increases taste bud size, and promotes gustatory innervation.

    PubMed

    Nosrat, Irina V; Margolskee, Robert F; Nosrat, Christopher A

    2012-05-11

    Brain-derived neurotrophic factor (BDNF) is the most potent neurotrophic factor in the peripheral taste system during embryonic development. It is also expressed in adult taste buds. There is a lack of understanding of the role of BDNF in the adult taste system. To address this, we generated novel transgenic mice in which transgene expression was driven by an α-gustducin promoter coupling BDNF expression to the postnatal expression of gustducin in taste cells. Immunohistochemistry revealed significantly stronger BDNF labeling in taste cells of high BDNF-expressing mouse lines compared with controls. We show that taste buds in these mice are significantly larger and have a larger number of taste cells compared with controls. To examine whether innervation was affected in Gust-BDNF mice, we used antibodies to neural cell adhesion molecule (NCAM) and ATP receptor P2X3. The total density of general innervation and specifically the gustatory innervation was markedly increased in high BDNF-expressing mice compared with controls. TrkB and NCAM gene expression in laser capture microdissected taste epithelia were significantly up-regulated in these mice. Up-regulation of TrkB transcripts in taste buds and elevated taste cell-specific TrkB phosphorylation in response to increased BDNF levels indicate that BDNF controls the expression and activation of its high affinity receptor in taste cells. This demonstrates a direct taste cell function for BDNF. BDNF also orchestrates and maintains taste bud innervation. We propose that the Gust-BDNF transgenic mouse models can be employed to further dissect the specific roles of BDNF in the adult taste system.

  8. Targeted Taste Cell-specific Overexpression of Brain-derived Neurotrophic Factor in Adult Taste Buds Elevates Phosphorylated TrkB Protein Levels in Taste Cells, Increases Taste Bud Size, and Promotes Gustatory Innervation*

    PubMed Central

    Nosrat, Irina V.; Margolskee, Robert F.; Nosrat, Christopher A.

    2012-01-01

    Brain-derived neurotrophic factor (BDNF) is the most potent neurotrophic factor in the peripheral taste system during embryonic development. It is also expressed in adult taste buds. There is a lack of understanding of the role of BDNF in the adult taste system. To address this, we generated novel transgenic mice in which transgene expression was driven by an α-gustducin promoter coupling BDNF expression to the postnatal expression of gustducin in taste cells. Immunohistochemistry revealed significantly stronger BDNF labeling in taste cells of high BDNF-expressing mouse lines compared with controls. We show that taste buds in these mice are significantly larger and have a larger number of taste cells compared with controls. To examine whether innervation was affected in Gust-BDNF mice, we used antibodies to neural cell adhesion molecule (NCAM) and ATP receptor P2X3. The total density of general innervation and specifically the gustatory innervation was markedly increased in high BDNF-expressing mice compared with controls. TrkB and NCAM gene expression in laser capture microdissected taste epithelia were significantly up-regulated in these mice. Up-regulation of TrkB transcripts in taste buds and elevated taste cell-specific TrkB phosphorylation in response to increased BDNF levels indicate that BDNF controls the expression and activation of its high affinity receptor in taste cells. This demonstrates a direct taste cell function for BDNF. BDNF also orchestrates and maintains taste bud innervation. We propose that the Gust-BDNF transgenic mouse models can be employed to further dissect the specific roles of BDNF in the adult taste system. PMID:22442142

  9. A conformational mimetic approach for the synthesis of carbocyclic nucleosides as anti-HCV leads.

    PubMed

    Kasula, Mohan; Balaraju, Tuniki; Toyama, Massaki; Thiyagarajan, Anandarajan; Bal, Chandralata; Baba, Masanori; Sharon, Ashoke

    2013-10-01

    Computer-aided approaches coupled with medicinal chemistry were used to explore novel carbocyclic nucleosides as potential anti-hepatitis C virus (HCV) agents. Conformational analyses were carried out on 6-amino-1H-pyrazolo[3,4-d]pyrimidine (6-APP)-based carbocyclic nucleoside analogues, which were considered as nucleoside mimetics to act as HCV RNA-dependent RNA polymerase (RdRp) inhibitors. Structural insight gained from the modeling studies revealed the molecular basis behind these nucleoside mimetics. The rationally chosen 6-APP analogues were prepared and evaluated for anti-HCV activity. RdRp SiteMap analysis revealed the presence of a hydrophobic cavity near C7 of the nucleosides; introduction of bulkier substituents at this position enhanced their activity. Herein we report the identification of an iodinated compound with an EC50 value of 6.6 μM as a preliminary anti-HCV lead. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. One step electro-oxidative preparation of graphene quantum dots from wood charcoal as a peroxidase mimetic.

    PubMed

    Nirala, Narsingh R; Khandelwal, Gaurav; Kumar, Brijesh; Vinita; Prakash, Rajiv; Kumar, Vinod

    2017-10-01

    In present study, we highlight one-step electrochemical synthesis of nearly uniform size (~ 5nm) of graphene quantum dots (E-GQDs) from wood charcoal and their further application as a peroxidase enzyme mimetic. The structural and optical properties of as-synthesized E-GQDs were probed by TEM, AFM, and spectroscopic techniques. Peroxidase enzyme mimetic potential of E-GQDs were examined for colorimetric detection of H2O2 and glucose. E-GQDs allowed a rapid and sensitive detection of glucose with a detection limit of 0.006mM for dynamic response range of 0.01-0.6mM. The calculated higher value of Vmax (7.2 × 10(-7)Ms(-1)) along with lower Km (0.012mM) corroborate enhanced the peroxidase-like activity of E-GQDs. Study introduces a cheap and widely available raw material for the electrochemical synthesis of graphene quantum dots with commendable enzyme mimetic activity which may have a huge impact in developing calorimetric bioanalysis systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Glucocorticoid regulates TrkB protein levels via c-Cbl dependent ubiquitination: a decrease in c-Cbl mRNA in the prefrontal cortex of suicide subjects.

    PubMed

    Pandya, Chirayu; Kutiyanawalla, Ammar; Turecki, Gustavo; Pillai, Anilkumar

    2014-07-01

    Brain derived neurotrophic factor (BDNF) signaling through its receptor TrkB plays a crucial role in neurodevelopment and plasticity. Stress and glucocorticoids have been shown to alter TrkB signaling in neurons, and defects in TrkB expression have been reported in the prefrontal cortex of suicide subjects. Glucocorticoid treatment has been shown to induce deleterious effects on the neuronal maturation. However, the mechanisms involved in the regulation of TrkB by glucocorticoid during neurodevelopment are not clear. Here we show that acute corticosterone exposure induced posttranslational upregulation of TrkB in primary cortical neurons (days in vitro 4, DIV4), which was blocked by the proteasome inhibitors. Acute corticosterone-induced increase in TrkB protein levels was dependent on glucocorticoid receptor (GR). At the cellular level, ubiquitin E3 ligase c-Cbl mediates TrkB stabilization and corticosterone-induced TrkB levels. Moreover, the tyrosine kinase binding domain in c-Cbl plays a critical role in corticosterone-induced TrkB levels. Chronic treatment of neurons with corticosterone induced significant decreases in both TrkB and c-Cbl protein levels. Acute corticosterone treatment failed to induce any significant change in TrkB and c-Cbl protein levels in mature neurons (DIV 12), where as chronic corticosterone exposure reduced TrkB levels. Under an in vivo condition, chronic corticosterone exposure induced down-regulation of c-Cbl in mouse frontal cortex and hippocampus. Importantly, we demonstrate for the first time a significant decrease in c-Cbl mRNA levels in the prefrontal cortex of suicide subjects indicating the possible role of c-Cbl in the pathophysiology of suicidal behavior. Thus, ubiquitin-proteasome-mediated TrkB regulation may be an important mechanism for improving BDNF signaling and maintaining neuroplasticity in stress-related neuropsychiatric disorders.

  12. The polysialic acid mimetics 5-nonyloxytryptamine and vinorelbine facilitate nervous system repair

    PubMed Central

    Saini, Vedangana; Lutz, David; Kataria, Hardeep; Kaur, Gurcharan; Schachner, Melitta; Loers, Gabriele

    2016-01-01

    Polysialic acid (PSA) is a large negatively charged glycan mainly attached to the neural cell adhesion molecule (NCAM). Several studies have shown that it is important for correct formation of brain circuitries during development and for synaptic plasticity, learning and memory in the adult. PSA also plays a major role in nervous system regeneration following injury. As a next step for clinical translation of PSA based therapeutics, we have previously identified the small organic compounds 5-nonyloxytryptamine and vinorelbine as PSA mimetics. Activity of 5-nonyloxytryptamine and vinorelbine had been confirmed in assays with neural cells from the central and peripheral nervous system in vitro and shown to be independent of their function as serotonin receptor 5-HT1B/1D agonist or cytostatic drug, respectively. As we show here in an in vivo paradigm for spinal cord injury in mice, 5-nonyloxytryptamine and vinorelbine enhance regain of motor functions, axonal regrowth, motor neuron survival and remyelination. These data indicate that 5-nonyloxytryptamine and vinorelbine may be re-tasked from their current usage as a 5-HT1B/1D agonist or cytostatic drug to act as mimetics for PSA to stimulate regeneration after injury in the mammalian nervous system. PMID:27324620

  13. Prussian blue nanoparticles as peroxidase mimetics for sensitive colorimetric detection of hydrogen peroxide and glucose.

    PubMed

    Zhang, Weimin; Ma, Diao; Du, Jianxiu

    2014-03-01

    Prussian blue nanoparticles (PB NPs) exhibits an intrinsic peroxidase-like catalytic activity towards the hydrogen peroxide (H2O2)-mediated oxidation of classical peroxidase substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt to produce a colored product. The catalysis follows Michaelis-Menen kinetics and shows strong affinity for H2O2. Using PB NPs as a peroxidase mimetics, a colorimetric method was developed for the detection of 0.05-50.0 μM H2O2, with a detection limit of 0.031 μM. When the catalytic reaction of PB NPs was coupled with the reaction of glucose oxidation catalyzed by glucose oxidase, a sensitive and selective colorimetric method for the detection of glucose was realized. The limit of detection for glucose was determined to be as low as 0.03 μM and the linear range was from 0.1 μM to 50.0 μM. The method was successfully applied to the determination of glucose in human serum. Compared with other nanomaterials-based peroxidase mimetics, PB NPs provides 10-100 times higher sensitivity toward the detection of H2O2 and glucose. The detection platform developed showed great potential applications in varieties of physiological importance substances when merged with appropriate H2O2-producing oxidases. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Evidence for a Müllerian mimetic radiation in Asian pitvipers

    PubMed Central

    Sanders, K.L; Malhotra, A; Thorpe, R.S

    2006-01-01

    Müllerian mimicry, in which toxic species gain mutual protection from shared warning signals, is poorly understood in vertebrates, reflecting a paucity of examples. Indirect evidence for mimicry is found if monophyletic species or clades show parallel geographic variation in warning patterns. Here, we evaluate a hypothesis of Müllerian mimicry for the pitvipers in Southeast Asia using a phylogeny derived from DNA sequences from four combined mitochondrial regions. Mantel matrix correlation tests show that conspicuous red colour pattern elements are significantly associated with sympatric and parapatric populations in four genera. To our knowledge, this represents the first evidence of a Müllerian mimetic radiation in vipers. The putative mimetic patterns are rarely found in females. This appears paradoxical in light of the Müllerian prediction of monomorphism, but may be explained by divergent selection pressures on the sexes, which have different behaviours. We suggest that biased predation on active males causes selection for protective warning coloration, whereas crypsis is favoured in relatively sedentary females. PMID:16600892

  15. A biologically effective fullerene (C60) derivative with superoxide dismutase mimetic properties.

    PubMed

    Ali, Sameh S; Hardt, Joshua I; Quick, Kevin L; Kim-Han, Jeong Sook; Erlanger, Bernard F; Huang, Ting-Ting; Epstein, Charles J; Dugan, Laura L

    2004-10-15

    Superoxide, a potentially toxic by-product of cellular metabolism, may contribute to tissue injury in many types of human disease. Here we show that a tris-malonic acid derivative of the fullerene C60 molecule (C3) is capable of removing the biologically important superoxide radical with a rate constant (k(C3)) of 2 x 10(6) mol(-1) s(-1), approximately 100-fold slower than the superoxide dismutases (SOD), a family of enzymes responsible for endogenous dismutation of superoxide. This rate constant is within the range of values reported for several manganese-containing SOD mimetic compounds. The reaction between C3 and superoxide was not via stoichiometric "scavenging," as expected, but through catalytic dismutation of superoxide, indicated by lack of structural modifications to C3, regeneration of oxygen, production of hydrogen peroxide, and absence of EPR-active (paramagnetic) products, all consistent with a catalytic mechanism. A model is proposed in which electron-deficient regions on the C60 sphere work in concert with malonyl groups attached to C3 to electrostatically guide and stabilize superoxide, promoting dismutation. We also found that C3 treatment of Sod2(-/-) mice, which lack expression of mitochondrial manganese superoxide dismutase (MnSOD), increased their life span by 300%. These data, coupled with evidence that C3 localizes to mitochondria, suggest that C3 functionally replaces MnSOD, acting as a biologically effective SOD mimetic.

  16. Inhibition of Antiapoptotic BCL-XL, BCL-2, and MCL-1 Proteins by Small Molecule Mimetics

    PubMed Central

    Dalafave, D.S.; Prisco, G.

    2010-01-01

    Informatics and computational design methods were used to create new molecules that could potentially bind antiapoptotic proteins, thus promoting death of cancer cells. Apoptosis is a cellular process that leads to the death of damaged cells. Its malfunction can cause cancer and poor response to conventional chemotherapy. After being activated by cellular stress signals, proapoptotic proteins bind antiapoptotic proteins, thus allowing apoptosis to go forward. An excess of antiapoptotic proteins can prevent apoptosis. Designed molecules that mimic the roles of proapoptotic proteins can promote the death of cancer cells. The goal of our study was to create new putative mimetics that could simultaneously bind several antiapoptotic proteins. Five new small molecules were designed that formed stable complexes with BCL-2, BCL-XL, and MCL-1 antiapoptotic proteins. These results are novel because, to our knowledge, there are not many, if any, small molecules known to bind all three proteins. Drug-likeness studies performed on the designed molecules, as well as previous experimental and preclinical studies on similar agents, strongly suggest that the designed molecules may indeed be promising drug candidates. All five molecules showed “drug-like” properties and had overall drug-likeness scores between 81% and 96%. A single drug based on these mimetics should cost less and cause fewer side effects than a combination of drugs each aimed at a single protein. Computer-based molecular design promises to accelerate drug research by predicting potential effectiveness of designed molecules prior to laborious experiments and costly preclinical trials. PMID:20838611

  17. Evidence for a Müllerian mimetic radiation in Asian pitvipers.

    PubMed

    Sanders, K L; Malhotra, A; Thorpe, R S

    2006-05-07

    Müllerian mimicry, in which toxic species gain mutual protection from shared warning signals, is poorly understood in vertebrates, reflecting a paucity of examples. Indirect evidence for mimicry is found if monophyletic species or clades show parallel geographic variation in warning patterns. Here, we evaluate a hypothesis of Müllerian mimicry for the pitvipers in Southeast Asia using a phylogeny derived from DNA sequences from four combined mitochondrial regions. Mantel matrix correlation tests show that conspicuous red colour pattern elements are significantly associated with sympatric and parapatric populations in four genera. To our knowledge, this represents the first evidence of a Müllerian mimetic radiation in vipers. The putative mimetic patterns are rarely found in females. This appears paradoxical in light of the Müllerian prediction of monomorphism, but may be explained by divergent selection pressures on the sexes, which have different behaviours. We suggest that biased predation on active males causes selection for protective warning coloration, whereas crypsis is favoured in relatively sedentary females.

  18. Minimalist Antibodies and Mimetics: An Update and Recent Applications.

    PubMed

    Bruce, Virginia J; Ta, Angeline N; McNaughton, Brian R

    2016-10-17

    The immune system utilizes antibodies to recognize foreign or disease-relevant receptors, initiating an immune response to destroy unwelcomed guests. Because researchers can evolve antibodies to bind virtually any target, it is perhaps unsurprising that these reagents, and their small-molecule conjugates, are used extensively in clinical and basic research environments. However, virtues of antibodies are countered by significant challenges. Foremost among these is the need for expression in mammalian cells (largely due to often necessary post-translational modifications). In response to these challenges, researchers have developed an array of minimalist antibodies and mimetics, which are smaller, more stable, simpler to express in Escherichia coli, and amendable to laboratory evolution and protein engineering. Here we describe these scaffolds and discuss recent applications of minimalist antibodies and mimetics. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Imperfect Batesian mimicry and the conspicuousness costs of mimetic resemblance.

    PubMed

    Speed, Michael P; Ruxton, Graeme D

    2010-07-01

    We apply signal detection methodology to make predictions about the evolution of Batesian mimicry. Our approach is novel in three ways. First, we applied a deterministic evolutionary modeling system that allows a large number of alternative mimetic morphs to coexist and compete. Second, we considered that there may be natural boundaries to phenotypic expression. Finally, we allowed increasing conspicuousness to impose an increasing detection cost on mimics. In some instances, the model predicts widespread variation in mimetic forms at evolutionary stability. In other situations, rather than a polymorphism the model predicts dimorphisms in which some prey were maximally cryptic and had minimal resemblance to the model, whereas many others were more conspicuous than the model. The biological implications of these results, particularly for our understanding of imperfect mimicry, are discussed.

  20. Small-molecule SMAC mimetics as new cancer therapeutics.

    PubMed

    Bai, Longchuan; Smith, David C; Wang, Shaomeng

    2014-10-01

    Apoptosis is a tightly regulated cellular process and faulty regulation of apoptosis is a hallmark of human cancers. Targeting key apoptosis regulators with the goal to restore apoptosis in tumor cells has been pursued as a new cancer therapeutic strategy. XIAP, cIAP1, and cIAP2, members of inhibitor of apoptosis (IAP) proteins, are critical regulators of cell death and survival and are attractive targets for new cancer therapy. The SMAC/DIABLO protein is an endogenous antagonist of XIAP, cIAP1, and cIAP2. In the last decade, intense research efforts have resulted in the design and development of several small-molecule SMAC mimetics now in clinical trials for cancer treatment. In this review, we will discuss the roles of XIAP, cIAP1, and cIAP2 in regulation of cell death and survival, and the design and development of small-molecule SMAC mimetics as novel cancer treatments.

  1. On (in)stabilities of perturbations in mimetic models with higher derivatives

    NASA Astrophysics Data System (ADS)

    Zheng, Yunlong; Shen, Liuyuan; Mou, Yicen; Li, Mingzhe

    2017-08-01

    Usually when applying the mimetic model to the early universe, higher derivative terms are needed to promote the mimetic field to be dynamical. However such models suffer from the ghost and/or the gradient instabilities and simple extensions cannot cure this pathology. We point out in this paper that it is possible to overcome this difficulty by considering the direct couplings of the higher derivatives of the mimetic field to the curvature of the spacetime.

  2. Dynamical behavior in mimetic F(R) gravity

    SciTech Connect

    Leon, Genly; Saridakis, Emmanuel N. E-mail: Emmanuel_Saridakis@baylor.edu

    2015-04-01

    We investigate the cosmological behavior of mimetic F(R) gravity. This scenario is the F(R) extension of usual mimetic gravity classes, which are based on re-parametrizations of the metric using new, but not propagating, degrees of freedom, that can lead to a wider family of solutions. Performing a detailed dynamical analysis for exponential, power-law, and arbitrary F(R) forms, we extracted the corresponding critical points. Interestingly enough, we found that although the new features of mimetic F(R) gravity can affect the universe evolution at early and intermediate times, at late times they will not have any effect, and the universe will result at stable states that coincide with those of usual F(R) gravity. However, this feature holds for the late-time background evolution only. On the contrary, the behavior of the perturbations is expected to be different since the new term contributes to the perturbations even if it does not contribute at the background level.

  3. Recovering a MOND-like acceleration law in mimetic gravity

    NASA Astrophysics Data System (ADS)

    Vagnozzi, Sunny

    2017-09-01

    We reconsider the recently proposed mimetic gravity, focusing in particular on whether the theory is able to reproduce the inferred flat rotation curves of galaxies. We extend the theory by adding a non-minimal coupling between matter and mimetic field. Such coupling leads to the appearance of an extra force which renders the motion of test particles non-geodesic. By studying the weak field limit of the resulting equations of motion, we demonstrate that in the Newtonian limit the acceleration law induced by the non-minimal coupling reduces to a modified Newtonian dynamics (MOND)-like one. In this way, it is possible to reproduce the successes of MOND, namely the explanation for the flat galactic rotation curves and the Tully–Fisher relation, within the framework of mimetic gravity, without the need for particle dark matter. The scale-dependence of the recovered acceleration scale opens up the possibility of addressing the missing mass problem not only on galactic but also on cluster scales: we defer a full study of this issue, together with a complete analysis of fits to spiral galaxy rotation curves, to an upcoming companion paper.

  4. Exosome mimetics: a novel class of drug delivery systems.

    PubMed

    Kooijmans, Sander A A; Vader, Pieter; van Dommelen, Susan M; van Solinge, Wouter W; Schiffelers, Raymond M

    2012-01-01

    The identification of extracellular phospholipid vesicles as conveyors of cellular information has created excitement in the field of drug delivery. Biological therapeutics, including short interfering RNA and recombinant proteins, are prone to degradation, have limited ability to cross biological membranes, and may elicit immune responses. Therefore, delivery systems for such drugs are under intensive investigation. Exploiting extracellular vesicles as carriers for biological therapeutics is a promising strategy to overcome these issues and to achieve efficient delivery to the cytosol of target cells. Exosomes are a well studied class of extracellular vesicles known to carry proteins and nucleic acids, making them especially suitable for such strategies. However, the considerable complexity and the related high chance of off-target effects of these carriers are major barriers for translation to the clinic. Given that it is well possible that not all components of exosomes are required for their proper functioning, an alternative strategy would be to mimic these vesicles synthetically. By assembly of liposomes harboring only crucial components of natural exosomes, functional exosome mimetics may be created. The low complexity and use of well characterized components strongly increase the pharmaceutical acceptability of such systems. However, exosomal components that would be required for the assembly of functional exosome mimetics remain to be identified. This review provides insights into the composition and functional properties of exosomes, and focuses on components which could be used to enhance the drug delivery properties of exosome mimetics.

  5. Exosome mimetics: a novel class of drug delivery systems

    PubMed Central

    Kooijmans, Sander AA; Vader, Pieter; van Dommelen, Susan M; van Solinge, Wouter W; Schiffelers, Raymond M

    2012-01-01

    The identification of extracellular phospholipid vesicles as conveyors of cellular information has created excitement in the field of drug delivery. Biological therapeutics, including short interfering RNA and recombinant proteins, are prone to degradation, have limited ability to cross biological membranes, and may elicit immune responses. Therefore, delivery systems for such drugs are under intensive investigation. Exploiting extracellular vesicles as carriers for biological therapeutics is a promising strategy to overcome these issues and to achieve efficient delivery to the cytosol of target cells. Exosomes are a well studied class of extracellular vesicles known to carry proteins and nucleic acids, making them especially suitable for such strategies. However, the considerable complexity and the related high chance of off-target effects of these carriers are major barriers for translation to the clinic. Given that it is well possible that not all components of exosomes are required for their proper functioning, an alternative strategy would be to mimic these vesicles synthetically. By assembly of liposomes harboring only crucial components of natural exosomes, functional exosome mimetics may be created. The low complexity and use of well characterized components strongly increase the pharmaceutical acceptability of such systems. However, exosomal components that would be required for the assembly of functional exosome mimetics remain to be identified. This review provides insights into the composition and functional properties of exosomes, and focuses on components which could be used to enhance the drug delivery properties of exosome mimetics. PMID:22619510

  6. Highest trkB mRNA expression in the entorhinal cortex among hippocampal subregions in the adult rat: contrasting pattern with BDNF mRNA expression.

    PubMed

    Tokuyama, W; Hashimoto, T; Li, Y X; Okuno, H; Miyashita, Y

    1998-11-20

    Brain-derived neurotrophic factor (BDNF) and its receptor, TrkB, regulate synaptic functions in the hippocampus of the adult rodent. In previous studies, in situ hybridization methods have been used to evaluate regional differences in BDNF and trkB mRNA expression levels in hippocampal subregions. However, these studies have failed to reach consensus regarding the regional differences in the mRNA expression levels. In the present study, we quantitated mRNA expression levels using two different methods, ribonuclease protection assays and a quantitative reverse-transcription polymerase chain reaction technique, in four hippocampal subregions: the entorhinal cortex, dentate gyrus (DG), CA3 and CA1. These two methods yielded the same results. We found that BDNF and trkB mRNA expression levels did not covary in the four subregions. BDNF and full length trkB (trkB FL) mRNA in the entorhinal cortex and the DG show contrasting expression patterns. The expression level of BDNF mRNA was highest in the DG among the hippocampal subregions and low in the entorhinal cortex and the CA1, whereas the trkB FL mRNA expression level was highest in the entorhinal cortex, low in the DG and lowest in the CA3. These results suggest regional differences in BDNF/TrkB signaling for maintenance and modifiability of neuronal connections in the hippocampal formation.

  7. Synthetic, structural mimetics of the β-hairpin flap of HIV-1 protease inhibit enzyme function.

    PubMed

    Chauhan, Jay; Chen, Shen-En; Fenstermacher, Katherine J; Naser-Tavakolian, Aurash; Reingewertz, Tali; Salmo, Rosene; Lee, Christian; Williams, Emori; Raje, Mithun; Sundberg, Eric; DeStefano, Jeffrey J; Freire, Ernesto; Fletcher, Steven

    2015-11-01

    Small-molecule mimetics of the β-hairpin flap of HIV-1 protease (HIV-1 PR) were designed based on a 1,4-benzodiazepine scaffold as a strategy to interfere with the flap-flap protein-protein interaction, which functions as a gated mechanism to control access to the active site. Michaelis-Menten kinetics suggested our small-molecules are competitive inhibitors, which indicates the mode of inhibition is through binding the active site or sterically blocking access to the active site and preventing flap closure, as designed. More generally, a new bioactive scaffold for HIV-1PR inhibition has been discovered, with the most potent compound inhibiting the protease with a modest K(i) of 11 μM. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Resistance to BH3 mimetic S1 in SCLC cells that up-regulate and phosphorylate Bcl-2 through ERK1/2.

    PubMed

    Liu, Yubo; Zhang, Zhichao; Song, Ting; Liang, Furong; Xie, Mingzhou; Sheng, Hongkun

    2013-08-01

    B cell lymphoma 2 (Bcl-2) is a central regulator of cell survival that is overexpressed in the majority of small-cell lung cancers (SCLC) and contributes to both malignant transformation and therapeutic resistance. The purpose of this work was to study the key factors that determine the sensitivity of SCLC cells to Bcl-2 homology domain-3 (BH3) mimetic S1 and the mechanism underlying the resistance of BH3 mimetics. Western blot was used to evaluate the contribution of Bcl-2 family members to the cellular response of SCLC cell lines to S1. Acquired resistant cells were derived from initially sensitive H1688 cells. Quantitative PCR and gene silencing were performed to investigate Bcl-2 up-regulation. A progressive increase in the relative levels of Bcl-2 and phosphorylated Bcl-2 (pBcl-2) characterized the increased de novo and acquired resistance of SCLC cell lines. Furthermore, acute treatment of S1 induced Bcl-2 expression and phosphorylation. We showed that BH3 mimetics, including S1 and ABT-737, induced endoplasmic reticulum (ER) stress and then activated MAPK/ERK pathway. The dual function of MAPK/ERK pathway in defining BH3 mimetics was illustrated; ERK1/2 activation leaded to Bcl-2 transcriptional up-regulation and sustained phosphorylation in naïve and acquired resistant SCLC cells. pBcl-2 played a key role in creating resistance of S1 and ABT-737 not only by sequestrating pro-apoptotic proteins, but also sequestrating a positive feedback to promote ERK1/2 activation. These results provide significant novel insights into the molecular mechanisms for crosstalk between ER stress and endogenously apoptotic pathways in SCLC following BH3 mimetics treatment. © 2013 The British Pharmacological Society.

  9. Resistance to BH3 mimetic S1 in SCLC cells that up-regulate and phosphorylate Bcl-2 through ERK1/2

    PubMed Central

    Liu, Yubo; Zhang, Zhichao; Song, Ting; Liang, Furong; Xie, Mingzhou; Sheng, Hongkun

    2013-01-01

    Background and Purpose B cell lymphoma 2 (Bcl-2) is a central regulator of cell survival that is overexpressed in the majority of small-cell lung cancers (SCLC) and contributes to both malignant transformation and therapeutic resistance. The purpose of this work was to study the key factors that determine the sensitivity of SCLC cells to Bcl-2 homology domain-3 (BH3) mimetic S1 and the mechanism underlying the resistance of BH3 mimetics. Experimental Approaches Western blot was used to evaluate the contribution of Bcl-2 family members to the cellular response of SCLC cell lines to S1. Acquired resistant cells were derived from initially sensitive H1688 cells. Quantitative PCR and gene silencing were performed to investigate Bcl-2 up-regulation. Key Results A progressive increase in the relative levels of Bcl-2 and phosphorylated Bcl-2 (pBcl-2) characterized the increased de novo and acquired resistance of SCLC cell lines. Furthermore, acute treatment of S1 induced Bcl-2 expression and phosphorylation. We showed that BH3 mimetics, including S1 and ABT-737, induced endoplasmic reticulum (ER) stress and then activated MAPK/ERK pathway. The dual function of MAPK/ERK pathway in defining BH3 mimetics was illustrated; ERK1/2 activation leaded to Bcl-2 transcriptional up-regulation and sustained phosphorylation in naïve and acquired resistant SCLC cells. pBcl-2 played a key role in creating resistance of S1 and ABT-737 not only by sequestrating pro-apoptotic proteins, but also sequestrating a positive feedback to promote ERK1/2 activation. Conclusions and Implications These results provide significant novel insights into the molecular mechanisms for crosstalk between ER stress and endogenously apoptotic pathways in SCLC following BH3 mimetics treatment. PMID:23651505

  10. Analysis of Arg-Gly-Asp mimetics and soluble receptor of tumour necrosis factor as therapeutic modalities for concanavalin A induced hepatitis in mice.

    PubMed Central

    Bruck, R; Shirin, H; Hershkoviz, R; Lider, O; Kenet, G; Aeed, H; Matas, Z; Zaidel, L; Halpern, Z

    1997-01-01

    BACKGROUND/AIMS: It has been shown that synthetic non-peptidic analogues of Arg-Gly-Asp, a major cell adhesive ligand of extracellular matrix, prevented an increase in serum aminotransferase activity, as a manifestation of concanavalin A induced liver damage in mice. This study examined the effects of an Arg-Gly-Asp mimetic on liver histology and cytokine release in response to concanavalin A administration, and the efficacy of soluble receptor of tumour necrosis factor (TNF) alpha in preventing hepatitis in this model of liver injury. METHODS: Mice were pretreated with either the Arg-Gly-Asp mimetic SF-6,5 or recombinant soluble receptor of TNF alpha before their inoculation with 10 mg/kg concanavalin A. Liver enzymes, histology, and the serum values of TNF alpha and interleukin (IL)6 were examined. RESULTS: The histopathological damage in the liver, and the concanavalin A induced release of TNF alpha and IL6 were significantly inhibited by the synthetic Arg-Gly-Asp mimetic (p < 0.001). Liver injury, manifested by the increase in serum aminotransferase and cytokines, as well as by histological manifestations of hepatic damage, was effectively prevented by pretreatment of the mice with the soluble TNF receptor (p < 0.001). CONCLUSIONS: This study confirms the efficacy of a synthetic Arg-Gly-Asp mimetic and soluble TNF receptor in the prevention of immune mediated liver damage in mice. Images PMID:9155591

  11. Angiogenic Effects of Dimeric Dipeptide Mimetic of Loop 4 of Nerve Growth Factor.

    PubMed

    Kryzhanovskii, S A; Antipova, T A; Tsorin, I B; Pekeldina, E S; Stolyaruk, V N; Nikolaev, S V; Sorokina, A V; Gudasheva, T A; Seredenin, S B

    2016-08-01

    Angiogenic action of compound GK-2, a dimeric dipeptide mimetic of loop 4 of nerve growth factor (NGF), was studied in in vitro and in vivo experiments. Experiments on human endothelial cell culture HUVEC showed that compound GK-2 significantly (p<0.05) stimulated the initial stage of angiogenesis, and its angiogenic activity was not inferior to the reference neurotrophin NGF. In experiments with hindlimb ischemia modeled in rats, GK-2 (1 mg/kg intraperitoneally for 14 days) significantly increased the total length of capillary vessels (p<0.003) and the number of vessels per 1 mm2 ischemic tissue (p<0.001) in comparison with the control. Our findings indicate that under experimental conditions compound GK-2 exhibits not only angiogenic, but also anti-ischemic activity.

  12. Virtual ligand screening of α-glucosidase: Identification of a novel potent noncarbohydrate mimetic inhibitor.

    PubMed

    Hakamata, Wataru; Ishikawa, Ryosuke; Ushijima, Yoriko; Tsukagoshi, Takumi; Tamura, Saori; Hirano, Takako; Nishio, Toshiyuki

    2012-01-01

    5-Thiazoleacetamide derivatives of AR122 and AR125 were screened as α-glucosidase inhibitors by in silico high-throughput screening from commercial drug-like small compound libraries. Inhibition of α-glucosidase with AR122 and AR125 is time dependent: with no preincubation, AR122 and AR125 are relatively moderate inhibitors, but interestingly, after a 120 min incubation, they were 50-fold more potent (AR122: IC(50)=2.47 μM and AR125: IC(50)=27.1 μM). Plots of ln [residual α-glucosidase activity %] versus preincubation time show a pseudo-first order kinetics for both inhibitors. Through dialysis of enzyme-inhibitor complexes, no activity recovery was shown. These results suggest that AR122 and AR125 constitute a new class of noncarbohydrate mimetic inhibitor with an irreversible mechanism.

  13. ω-Conotoxin GVIA Mimetics that Bind and Inhibit Neuronal Cav2.2 Ion Channels

    PubMed Central

    Tranberg, Charlotte Elisabet; Yang, Aijun; Vette, Irina; McArthur, Jeffrey R.; Baell, Jonathan B.; Lewis, Richard J.; Tuck, Kellie L.; Duggan, Peter J.

    2012-01-01

    The neuronal voltage-gated N-type calcium channel (Cav2.2) is a validated target for the treatment of neuropathic pain. A small library of anthranilamide-derived ω-Conotoxin GVIA mimetics bearing the diphenylmethylpiperazine moiety were prepared and tested using three experimental measures of calcium channel blockade. These consisted of a 125I-ω-conotoxin GVIA displacement assay, a fluorescence-based calcium response assay with SH-SY5Y neuroblastoma cells, and a whole-cell patch clamp electrophysiology assay with HEK293 cells stably expressing human Cav2.2 channels. A subset of compounds were active in all three assays. This is the first time that compounds designed to be mimics of ω-conotoxin GVIA and found to be active in the 125I-ω-conotoxin GVIA displacement assay have also been shown to block functional ion channels in a dose-dependent manner. PMID:23170089

  14. Pancreatic Cancer Combination Therapy Using a BH3 Mimetic and a Synthetic Tetracycline.

    PubMed

    Quinn, Bridget A; Dash, Rupesh; Sarkar, Siddik; Azab, Belal; Bhoopathi, Praveen; Das, Swadesh K; Emdad, Luni; Wei, Jun; Pellecchia, Maurizio; Sarkar, Devanand; Fisher, Paul B

    2015-06-01

    Improved treatments for pancreatic cancer remain a clinical imperative. Sabutoclax, a small-molecule BH3 mimetic, inhibits the function of antiapoptotic Bcl-2 proteins. Minocycline, a synthetic tetracycline, displays antitumor activity. Here, we offer evidence of the combinatorial antitumor potency of these agents in several preclinical models of pancreatic cancer. Sabutoclax induced growth arrest and apoptosis in pancreatic cancer cells and synergized with minocycline to yield a robust mitochondria-mediated caspase-dependent cytotoxicity. This combinatorial property relied upon loss of phosphorylated Stat3 insofar as reintroduction of activated Stat3-rescued cells from toxicity. Tumor growth was inhibited potently in both immune-deficient and immune-competent models with evidence of extended survival. Overall, our results showed that the combination of sabutoclax and minocycline was highly cytotoxic to pancreatic cancer cells and safely efficacious in vivo.

  15. Probing the Catalytic Charge-Relay System in Alanine Racemase with Genetically Encoded Histidine Mimetics.

    PubMed

    Sharma, Vangmayee; Wang, Yane-Shih; Liu, Wenshe R

    2016-12-16

    Histidine is a unique amino acid with an imidazole side chain in which both of the nitrogen atoms are capable of serving as a proton donor and proton acceptor in hydrogen bonding interactions. In order to probe the functional role of histidine involved in hydrogen bonding networks, fine-tuning the hydrogen bonding potential of the imidazole side chain is required but not feasible through traditional mutagenesis methods. Here, we show that two close mimetics of histidine, 3-methyl-histidine and thiazole alanine, can be genetically encoded using engineered pyrrolysine incorporation machinery. Replacement of the three histidine residues predicted to be involved in an extended charge-relay system in alanine racemase with 3-methyl-histidine or thiazole alanine shows a dramatic loss in the enzyme's catalytic efficiency, implying the role of this extended charge-relay system in activating the active site residue Y265, a general acid/base catalyst in the enzyme.

  16. Smac mimetic induces cell death in a large proportion of primary acute myeloid leukemia samples, which correlates with defined molecular markers

    PubMed Central

    Lueck, Sonja C.; Russ, Annika C.; Botzenhardt, Ursula; Schlenk, Richard F.; Zobel, Kerry; Deshayes, Kurt; Vucic, Domagoj; Döhner, Hartmut; Döhner, Konstanze

    2016-01-01

    Apoptosis is deregulated in most, if not all, cancers, including hematological malignancies. Smac mimetics that antagonize Inhibitor of Apoptosis (IAP) proteins have so far largely been investigated in acute myeloid leukemia (AML) cell lines; however, little is yet known on the therapeutic potential of Smac mimetics in primary AML samples. In this study, we therefore investigated the antileukemic activity of the Smac mimetic BV6 in diagnostic samples of 67 adult AML patients and correlated the response to clinical, cytogenetic and molecular markers and gene expression profiles. Treatment with cytarabine (ara-C) was used as a standard chemotherapeutic agent. Interestingly, about half (51%) of primary AML samples are sensitive to BV6 and 21% intermediate responsive, while 28% are resistant. Notably, 69% of ara-C-resistant samples show a good to fair response to BV6. Furthermore, combination treatment with ara-C and BV6 exerts additive effects in most samples. Whole-genome gene expression profiling identifies cell death, TNFR1 and NF-κB signaling among the top pathways that are activated by BV6 in BV6-sensitive, but not in BV6-resistant cases. Furthermore, sensitivity of primary AML blasts to BV6 correlates with significantly elevated expression levels of TNF and lower levels of XIAP in diagnostic samples, as well as with NPM1 mutation. In a large set of primary AML samples, these data provide novel insights into factors regulating Smac mimetic response in AML and have important implications for the development of Smac mimetic-based therapies and related diagnostics in AML. PMID:27385100

  17. Bivalent O-glycoside mimetics with S/disulfide/Se substitutions and aromatic core: Synthesis, molecular modeling and inhibitory activity on biomedically relevant lectins in assays of increasing physiological relevance.

    PubMed

    Kaltner, Herbert; Szabó, Tamás; Fehér, Krisztina; André, Sabine; Balla, Sára; Manning, Joachim C; Szilágyi, László; Gabius, Hans-Joachim

    2017-06-15

    The emerging significance of recognition of cellular glycans by lectins for diverse aspects of pathophysiology is a strong incentive for considering development of bioactive and non-hydrolyzable glycoside derivatives, for example by introducing S/Se atoms and the disulfide group instead of oxygen into the glycosidic linkage. We report the synthesis of 12 bivalent thio-, disulfido- and selenoglycosides attached to benzene/naphthalene cores. They present galactose, for blocking a plant toxin, or lactose, the canonical ligand of adhesion/growth-regulatory galectins. Modeling reveals unrestrained flexibility and inter-headgroup distances too small to bridge two sites in the same lectin. Inhibitory activity was first detected by solid-phase assays using a surface-presented glycoprotein, with relative activity enhancements per sugar unit relative to free cognate sugar up to nearly 10fold. Inhibitory activity was also seen on lectin binding to surfaces of human carcinoma cells. In order to proceed to characterize this capacity in the tissue context monitoring of lectin binding in the presence of inhibitors was extended to sections of three types of murine organs as models. This procedure proved to be well-suited to determine relative activity levels of the glycocompounds to block binding of the toxin and different human galectins to natural glycoconjugates at different sites in sections. The results on most effective inhibition by two naphthalene-based disulfides and a selenide raise the perspective for broad applicability of the histochemical assay in testing glycoclusters that target biomedically relevant lectins. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Expression of trkB mRNA is altered in rat hippocampus after experimental brain trauma.

    PubMed

    Hicks, R R; Zhang, L; Dhillon, H S; Prasad, M R; Seroogy, K B

    1998-08-31

    Recent investigations have shown that expression of mRNAs for the neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) is differentially altered in the hippocampus following traumatic brain injury. In the present study, modulation of neurotrophin receptor expression was examined in the hippocampus in a rat model of traumatic brain injury using in situ hybridization. Messenger RNA for trkB, the high-affinity receptor for BDNF and neurotrophin-4 (NT-4), was increased between 3 and 6 h bilaterally in the dentate gyrus following a lateral fluid-percussion brain injury of moderate severity (2.0-2.1 atm). No time-dependent alterations were observed for trkB mRNA in hippocampal subfields CA1 and CA3. Levels of mRNA for trkC, the high-affinity receptor for NT-3, did not change in any region of the hippocampus. These data demonstrate that lateral fluid-percussion injury modulates expression of trkB mRNA in the hippocampus and support a role for BDNF/trkB signalling mechanisms in secondary events associated with traumatic brain injury.

  19. TTIP is a novel protein that interacts with the truncated T1 TrkB neurotrophin receptor.

    PubMed

    Kryl, D; Barker, P A

    2000-12-29

    Alternative splicing of the TrkB gene produces a full length tyrosine kinase receptor as well as two truncated isoforms that contain extracellular and transmembrane domains but lack the kinase domain and have unique C terminal tails. The function of the truncated TrkB isoforms is unclear and to gain insights into their function, we have isolated a protein from 15N neuroblastoma cells that specifically binds the TrkB.T1 isoform. Pulldown experiments using a GST fusion protein containing the TrkB.T1 intracellular domain identified a 61 kDa protein from radiolabeled 15N lysates. Coimmunoprecipitation experiments showed that the 61 kDa protein interacted with epitope-tagged TrkB.T1 overexpressed in 15N cells as well as with TrkB.T1 which was endogenously expressed. Peptide competition experiments revealed that the protein, designated TTIP (for Truncated TrkB Interacting Protein), showed specific binding to the TrkB.T1 tail. MALDI MS and MS/MS analysis has revealed that TTIP is a novel protein not yet listed in the current databases.

  20. The in vivo contribution of motor neuron TrkB receptors to mutant SOD1 motor neuron disease.

    PubMed

    Zhai, Jinbin; Zhou, Weiguo; Li, Jian; Hayworth, Christopher R; Zhang, Lei; Misawa, Hidemi; Klein, Rudiger; Scherer, Steven S; Balice-Gordon, Rita J; Kalb, Robert Gordon

    2011-11-01

    Brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) are widely expressed in the vertebrate nervous system and play a central role in mature neuronal function. In vitro BDNF/TrkB signaling promotes neuronal survival and can help neurons resist toxic insults. Paradoxically, BDNF/TrkB signaling has also been shown, under certain in vitro circumstances, to render neurons vulnerable to insults. We show here that in vivo conditional deletion of TrkB from mature motor neurons attenuates mutant superoxide dismutase 1 (SOD1) toxicity. Mutant SOD1 mice lacking motor neuron TrkB live a month longer than controls and retain motor function for a longer period, particularly in the early phase of the disease. These effects are subserved by slowed motor neuron loss, persistence of neuromuscular junction integrity and reduced astrocytic and microglial reactivity within the spinal cord. These results suggest that manipulation of BDNF/TrkB signaling might have therapeutic efficacy in motor neuron diseases.

  1. Xiangshao Granule Exerts Antidepressive Effects in a Depression Mouse Model by Ameliorating Deficits in Hippocampal BDNF and TrkB

    PubMed Central

    Liu, Jie; Wu, Xiaoting; Nice, Edouard Collins

    2013-01-01

    This study explores the therapeutic effects of Xiangshao granules in a mouse depression model and examines the potential molecular mechanisms involved. After 21 consecutive days of chronic stress challenge, all mice were divided into three groups: control group, depression group, and Xiangshao granule treatment group. On the 22nd day, rats in the Xiangshao granule treatment group received Xiangshao granules via gastrogavage for 3 consecutive weeks. Depression group mice showed a significant reduction of crossings (P < 0.01) but not rearings (P < 0.05). Serum CRH, CORT, and ACTH levels were significantly increased in depression mice compared with control (P < 0.05) and the expression levels of hippocampal BDNF and TrkB were reduced in the model group (P < 0.05). However, Xiangshao granule treatment remarkably rescued the decrease in the body weight (P < 0.05), increased crossings in the open field test (P < 0.05), upregulated the expression of hippocampal BDNF and TrkB expression, and reduced the serum CRH, CORT, and ACTH concentrations compared with the depression group (P < 0.05). Collectively, these results demonstrated that Xiangshao granule could effectively induce antidepressive effects in the depression mouse model by ameliorating the expression of hippocampal BDNF and TrkB. PMID:24367385

  2. Thioredoxin-mimetic peptides (TXM) reverse auranofin induced apoptosis and restore insulin secretion in insulinoma cells.

    PubMed

    Cohen-Kutner, Moshe; Khomsky, Lena; Trus, Michael; Aisner, Yonatan; Niv, Masha Y; Benhar, Moran; Atlas, Daphne

    2013-04-01

    The thioredoxin reductase/thioredoxin system (TrxR/Trx1) plays a major role in protecting cells from oxidative stress. Disruption of the TrxR-Trx1 system keeps Trx1 in the oxidized state leading to cell death through activation of the ASK1-Trx1 apoptotic pathway. The potential mechanism and ability of tri- and tetra-oligopeptides derived from the canonical -CxxC- motif of the Trx1-active site to mimic and enhance Trx1 cellular activity was examined. The Trx mimetics peptides (TXM) protected insulinoma INS 832/13 cells from oxidative stress induced by selectively inhibiting TrxR with auranofin (AuF). TXM reversed the AuF-effects preventing apoptosis, and increasing cell-viability. The TXM peptides were effective in inhibiting AuF-induced MAPK, JNK and p38(MAPK) phosphorylation, in correlation with preventing caspase-3 cleavage and thereby PARP-1 dissociation. The ability to form a disulfide-bridge-like conformation was estimated from molecular dynamics simulations. The TXM peptides restored insulin secretion and displayed Trx1 denitrosylase activity. Their potency was 10-100-fold higher than redox reagents like NAC, AD4, or ascorbic acid. Unable to reverse ERK1/2 phosphorylation, TXM-CB3 (NAc-Cys-Pro-Cys amide) appeared to function in part, through inhibiting ASK1-Trx dissociation. These highly effective anti-apoptotic effects of Trx1 mimetic peptides exhibited in INS 832/13 cells could become valuable in treating adverse oxidative-stress related disorders such as diabetes. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. The BH3 Mimetic Obatoclax Accumulates in Lysosomes and Causes Their Alkalinization.

    PubMed

    Stamelos, Vasileios A; Fisher, Natalie; Bamrah, Harnoor; Voisey, Carolyn; Price, Joshua C; Farrell, William E; Redman, Charles W; Richardson, Alan

    2016-01-01

    Obatoclax belongs to a class of compounds known as BH3 mimetics which function as antagonists of Bcl-2 family apoptosis regulators. It has undergone extensive preclinical and clinical evaluation as a cancer therapeutic. Despite this, it is clear that obatoclax has additional pharmacological effects that contribute to its cytotoxic activity. It has been claimed that obatoclax, either alone or in combination with other molecularly targeted therapeutics, induces an autophagic form of cell death. In addition, obatoclax has been shown to inhibit lysosomal function, but the mechanism of this has not been elucidated. We have evaluated the mechanism of action of obatoclax in eight ovarian cancer cell lines. Consistent with its function as a BH3 mimetic, obatoclax induced apoptosis in three cell lines. However, in the remaining cell lines another form of cell death was evident because caspase activation and PARP cleavage were not observed. Obatoclax also failed to show synergy with carboplatin and paclitaxel, chemotherapeutic agents which we have previously shown to be synergistic with authentic Bcl-2 family antagonists. Obatoclax induced a profound accumulation of LC-3 but knockdown of Atg-5 or beclin had only minor effects on the activity of obatoclax in cell growth assays suggesting that the inhibition of lysosomal function rather than stimulation of autophagy may play a more prominent role in these cells. To evaluate how obatoclax inhibits lysosomal function, confocal microscopy studies were conducted which demonstrated that obatoclax, which contains two basic pyrrole groups, accumulates in lysosomes. Studies using pH sensitive dyes demonstrated that obatoclax induced lysosomal alkalinization. Furthermore, obatoclax was synergistic in cell growth/survival assays with bafilomycin and chloroquine, two other drugs which cause lysosomal alkalinization. These studies explain, for the first time, how obatoclax inhibits lysosomal function and suggest that lysosomal

  4. The consequences of selective inhibition of signal transducer and activator of transcription 3 (STAT3) tyrosine705 phosphorylation by phosphopeptide mimetic prodrugs targeting the Src homology 2 (SH2) domain

    PubMed Central

    McMurray, John S.; Mandal, Pijus K.; Liao, Warren S.; Klostergaard, Jim; Robertson, Fredika M.

    2012-01-01

    Herein we review our progress on the development of phosphopeptide-based prodrugs targeting the SH2 domain of STAT3 to prevent recruitment to cytokine and growth factor receptors, activation, nuclear translocation and transcription of genes involved in cancer. We developed high affinity phosphopeptides (KI = 46–200 nM). Corresponding prodrugs inhibited constitutive and IL-6 induced Tyr705 phosphorylation at 0.5–1 μM in a variety of human cancer cell lines. They were not cytotoxic at 5 μM in vitro but they inhibited tumor growth in a human xenograft breast cancer model in mice, accompanied by reduced VEGF expression and angiogenesis. PMID:24058783

  5. Expression of trkB and trkC receptors and their ligands brain-derived neurotrophic factor and neurotrophin-3 in the murine amygdala.

    PubMed

    Krause, S; Schindowski, K; Zechel, S; von Bohlen und Halbach, O

    2008-02-01

    The neurotrophin brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) and their cognate receptors, trkB and trkC, have a variety of physiological brain functions, ranging from cell survival to mechanisms involved in learning and memory and long-term potentiation (LTP). LTP can be induced in the cortex and hippocampus, as well as within the amygdala. However, the role of neurotrophins in amygdalar LTP is largely unknown. Expression patterns of BDNF and NT-3 and their cognate receptors in the adult mouse amygdala have not been analyzed in detail. We have therefore examined the expression of trkB, trkC, BDNF, and NT-3 mRNA and protein in different amygdalar nuclei as well as in the hippocampal areas CA1-CA3 and the dentate gyrus. The distribution pattern of trkB, trkC, BDNF, and NT-3 mRNA in the murine hippocampus is comparable to that seen in rats. Within most amygdalar nuclei, a moderate BDNF mRNA expression was found; however, BDNF mRNA was virtually absent from the central nucleus. No expression of NT-3 mRNA was found within the amygdala, but trkC mRNA-expressing cells were widely distributed within this brain region. trkB mRNA was strongly expressed in the amygdala. Because trkB is expressed in a full-length and a truncated form (the latter form is also expressed by nonneuronal cells), we also investigated the distribution of full-length trkB mRNA-expressing cells and could demonstrate that this version of trkB receptors is also widely expressed in the amygdala. These results can serve as a basis for studies elucidating the physiological roles of these receptors in the amygdala.

  6. Antidepressant Effects of TrkB Ligands on Depression-Like Behavior and Dendritic Changes in Mice After Inflammation

    PubMed Central

    Zhang, Ji-chun; Wu, Jin; Fujita, Yuko; Yao, Wei; Ren, Qian; Yang, Chun; Li, Su-xia; Shirayama, Yukihiko

    2015-01-01

    Background: Brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase B (TrkB), signaling represent potential therapeutic targets for major depressive disorder. The purpose of this study is to examine whether TrkB ligands show antidepressant effects in an inflammation-induced model of depression. Methods: In this study, we examined the effects of TrkB agonist 7,8-dihydroxyflavone (7,8-DHF) and TrkB antagonist ANA-12 on depression-like behavior and morphological changes in mice previously exposed to lipopolysaccharide (LPS). Protein levels of BDNF, phospho-TrkB (p-TrkB), and TrkB in the brain regions were also examined. Results: LPS caused a reduction of BDNF in the CA3 and dentate gyrus (DG) of the hippocampus and prefrontal cortex (PFC), whereas LPS increased BDNF in the nucleus accumbens (NAc). Dexamethason suppression tests showed hyperactivity of the hypothalamic-pituitary-adrenal axis in LPS-treated mice. Intraperitoneal (i.p.) administration of 7,8-DHF showed antidepressant effects on LPS-induced depression-like behavior, and i.p. pretreatment with ANA-12 blocked its antidepressant effects. Surprisingly, ANA-12 alone showed antidepressant-like effects on LPS-induced depression-like behavior. Furthermore, bilateral infusion of ANA-12 into the NAc showed antidepressant effects. Moreover, LPS caused a reduction of spine density in the CA3, DG, and PFC, whereas LPS increased spine density in the NAc. Interestingly, 7,8-DHF significantly attenuated LPS-induced reduction of p-TrkB and spine densities in the CA3, DG, and PFC, whereas ANA-12 significantly attenuated LPS-induced increases of p-TrkB and spine density in the NAc. Conclusions: The results suggest that LPS-induced inflammation may cause depression-like behavior by altering BDNF and spine density in the CA3, DG, PFC, and NAc, which may be involved in the antidepressant effects of 7,8-DHF and ANA-12, respectively. PMID:25628381

  7. Cisplatin-induced apoptosis in non-small-cell lung cancer cells is dependent on Bax- and Bak-induction pathway and synergistically activated by BH3-mimetic ABT-263 in p53 wild-type and mutant cells.

    PubMed

    Matsumoto, Masaru; Nakajima, Wataru; Seike, Masahiro; Gemma, Akihiko; Tanaka, Nobuyuki

    2016-04-29

    Cisplatin is a highly effective anticancer drug for treatment of various tumors including non-small-cell lung cancer (NSCLC), and is especially useful in cases nonresponsive to molecular-targeted drugs. Accumulating evidence has shown that cisplatin activates the p53-dependent apoptotic pathway, but it also induces apoptosis in p53-mutated cancer cells. Here we demonstrated that DNA-damage inducible proapoptotic BH3 (Bcl-2 homology region 3)-only Bcl-2 family members, Noxa, Puma, Bim and Bid, are not involved in cisplatin-induced apoptosis in human NSCLC cell lines. In contrast, the expression of proapoptotic multidomain Bcl-2-family members, Bak and Bax, was induced by cisplatin in p53-dependent and -independent manners, respectively. Moreover, in wild-type p53-expressing cells, cisplatin mainly used the Bak-dependent apoptotic pathway, but this apoptotic pathway shifted to the Bax-dependent pathway by loss-of-function of p53. Furthermore, both Bak- and Bax-induced apoptosis was enhanced by the antiapoptotic Bcl-2 family member, Bcl-XL knockdown, but not by Mcl-1 knockdown. From this result, we tested the effect of ABT-263 (Navitoclax), the specific inhibitor of Bcl-2 and Bcl-XL, but not Mcl-1, and found that ABT-263 synergistically enhanced cisplatin-induced apoptosis in NSCLC cells in the presence or absence of p53. These results indicate a novel regulatory system in cisplatin-induced NSCLC cell apoptosis, and a candidate efficient combination chemotherapy method against lung cancers.

  8. Phylogenetic codivergence supports coevolution of mimetic Heliconius butterflies.

    PubMed

    Cuthill, Jennifer Hoyal; Charleston, Michael

    2012-01-01

    The unpalatable and warning-patterned butterflies Heliconius erato and Heliconius melpomene provide the best studied example of mutualistic Müllerian mimicry, thought-but rarely demonstrated-to promote coevolution. Some of the strongest available evidence for coevolution comes from phylogenetic codivergence, the parallel divergence of ecologically associated lineages. Early evolutionary reconstructions suggested codivergence between mimetic populations of H. erato and H. melpomene, and this was initially hailed as one of the most striking known cases of coevolution. However, subsequent molecular phylogenetic analyses found discrepancies in phylogenetic branching patterns and timing (topological and temporal incongruence) that argued against codivergence. We present the first explicit cophylogenetic test of codivergence between mimetic populations of H. erato and H. melpomene, and re-examine the timing of these radiations. We find statistically significant topological congruence between multilocus coalescent population phylogenies of H. erato and H. melpomene. Cophylogenetic historical reconstructions support repeated codivergence of mimetic populations, from the base of the sampled radiations. Pairwise distance correlation tests, based on our coalescent analyses plus recently published AFLP and wing colour pattern gene data, also suggest that the phylogenies of H. erato and H. melpomene show significant topological congruence. Divergence time estimates, based on a Bayesian coalescent model, suggest that the evolutionary radiations of H. erato and H. melpomene occurred over the same time period, and are compatible with a series of temporally congruent codivergence events. Our results suggest that differences in within-species genetic divergence are the result of a greater overall effective population size for H. erato relative to H. melpomene and do not imply incongruence in the timing of their phylogenetic radiations. Repeated codivergence between Müllerian co

  9. Phylogenetic Codivergence Supports Coevolution of Mimetic Heliconius Butterflies

    PubMed Central

    Hoyal Cuthill, Jennifer; Charleston, Michael

    2012-01-01

    The unpalatable and warning-patterned butterflies Heliconius erato and Heliconius melpomene provide the best studied example of mutualistic Müllerian mimicry, thought–but rarely demonstrated–to promote coevolution. Some of the strongest available evidence for coevolution comes from phylogenetic codivergence, the parallel divergence of ecologically associated lineages. Early evolutionary reconstructions suggested codivergence between mimetic populations of H. erato and H. melpomene, and this was initially hailed as one of the most striking known cases of coevolution. However, subsequent molecular phylogenetic analyses found discrepancies in phylogenetic branching patterns and timing (topological and temporal incongruence) that argued against codivergence. We present the first explicit cophylogenetic test of codivergence between mimetic populations of H. erato and H. melpomene, and re-examine the timing of these radiations. We find statistically significant topological congruence between multilocus coalescent population phylogenies of H. erato and H. melpomene. Cophylogenetic historical reconstructions support repeated codivergence of mimetic populations, from the base of the sampled radiations. Pairwise distance correlation tests, based on our coalescent analyses plus recently published AFLP and wing colour pattern gene data, also suggest that the phylogenies of H. erato and H. melpomene show significant topological congruence. Divergence time estimates, based on a Bayesian coalescent model, suggest that the evolutionary radiations of H. erato and H. melpomene occurred over the same time period, and are compatible with a series of temporally congruent codivergence events. Our results suggest that differences in within-species genetic divergence are the result of a greater overall effective population size for H. erato relative to H. melpomene and do not imply incongruence in the timing of their phylogenetic radiations. Repeated codivergence between M

  10. Reproductive isolation related to mimetic divergence in the poison frog Ranitomeya imitator.

    PubMed

    Twomey, Evan; Vestergaard, Jacob S; Summers, Kyle

    2014-08-27

    In a mimetic radiation--when a single species evolves to resemble different model species--mimicry can drive within-species morphological diversification, and, potentially, speciation. While mimetic radiations have occurred in a variety of taxa, their role in speciation remains poorly understood. We study the Peruvian poison frog Ranitomeya imitator, a species that has undergone a mimetic radiation into four distinct morphs. Using a combination of colour-pattern analysis, landscape genetics and mate-choice experiments, we show that a mimetic shift in R. imitator is associated with a narrow phenotypic transition zone, neutral genetic divergence and assortative mating, suggesting that divergent selection to resemble different model species has led to a breakdown in gene flow between these two populations. These results extend the effects of mimicry on speciation into a vertebrate system and characterize an early stage of speciation where reproductive isolation between mimetic morphs is incomplete but evident.

  11. Initial testing (stage 1) of LCL161, a SMAC mimetic, by the Pediatric Preclinical Testing Program.

    PubMed

    Houghton, Peter J; Kang, Min H; Reynolds, C Patrick; Morton, Christopher L; Kolb, E Anders; Gorlick, Richard; Keir, Stephen T; Carol, Hernan; Lock, Richard; Maris, John M; Billups, Catherine A; Smith, Malcolm A

    2012-04-01

    LCL161, a SMAC mimetic, was tested against the PPTP in vitro panel (1.0 nM to 10.0 µM) and the PPTP in vivo panels (30 or 75 mg/kg [solid tumors] or 100 mg/kg [ALL]) administered orally twice in a week. LCL161 showed a median relative IC(50) value of >10 µM, being more potent against several leukemia and lymphoma lines. In vivo LCL161 induced significant differences in EFS distribution in approximately one-third of solid tumor xenografts (osteosarcoma and glioblastoma), but not in ALL xenografts. No objective tumor responses were observed. In vivo LCL161 demonstrated limited single agent activity against the pediatric preclinical models studied. Copyright © 2011 Wiley Periodicals, Inc.

  12. Synthesis of a sulfonic acid mimetic of the sulfated Lewis A pentasaccharide.

    PubMed

    Jakab, Zsolt; Fekete, Anikó; Csávás, Magdolna; Borbás, Anikó; Lipták, András; Antus, Sándor

    2012-03-01

    The first sulfonic acid mimetic of the sulfated Lewis A pentasaccharide in which the natural L-fucose unit is replaced by a D-arabinose ring was synthesized. Formation of the sulfonic acid moiety at a pentasaccharide level could be successfully achieved by means of introduction of an acetylthio moiety into the terminal D-galactose residue and subsequent oxidation. The equatorial arrangement of the acetylthio group linked to C-3 of the galactose ring could be obtained by double nucleophilic substitutions; efficient formation of the gulo-triflate derivatives required low-power microwave (MW) activation. Oxidation of the acetylthio group was carried out using Oxone in the presence of acetic acid.

  13. Asymmetric synthesis of highly substituted azapolycyclic compounds via 2-alkenyl sulfoximines: potential scaffolds for peptide mimetics.

    PubMed

    Reggelin, Michael; Junker, Bernd; Heinrich, Timo; Slavik, Stefan; Bühle, Philipp

    2006-03-29

    The application of metalated, enantiomerically pure acyclic and cyclic 2-alkenyl sulfoximines for the synthesis of highly substituted aza(poly)cyclic ring systems is described. The method relies on a one-pot combination of a reagent-controlled allyl transfer reaction to alpha- or beta-amino aldehydes, followed by a Michael-type cyclization of the intermediate vinyl sulfoximines generated in the first step. The sulfur-free target compounds are preferentially obtained by samarium iodide treatment of the sulfonimidoyl substituted heterocycles. In addition to this methodological work, initial results on the biological activity of selected examples are reported. Furthermore, a concept for the transformation of peptidic lead structures into non-peptide mimetics is described, and the relevance of the new approach to highly substituted azaheterocycles in this context is discussed.

  14. Microemulsions, micelles, and vesicles as media for membrane mimetic photochemistry

    SciTech Connect

    Fendler, J.H.

    1980-06-12

    Microemulsions, micelles, and vesicles are compared as media for membrane mimetic photochemistry. These systems solubilize, concentrate, compartmentalize, organize, and localize reactants; maintain proton and/or reactant gradients; alter quantum efficiencies; lower ionization potentials; change oxidation and reduction properties; change dissociation constants; affect vectorial electron displacements; alter photophysical pathways and rates; alter chemical pathways and rates; stabilize reactants, intermediates, and products; and separate products (charges). Formation of structures of microemulsions, micelles, and vesicles as well as substrate solubilization therein are summarized. Attention is focused on the utilization of microemulsions as reaction media. 72 references.

  15. Thrombin receptor (PAR-1) antagonists. Solid-phase synthesis of indole-based peptide mimetics by anchoring to a secondary amide.

    PubMed

    Zhang, H C; McComsey, D F; White, K B; Addo, M F; Andrade-Gordon, P; Derian, C K; Oksenberg, D; Maryanoff, B E

    2001-08-20

    A novel, 10-step, solid-phase method, based on a secondary amide linker, was developed to construct a diverse library of indole-based SFLLR peptide mimetics as thrombin receptor (protease-activated receptor 1, PAR-1) antagonists. The key steps include stepwise reductive alkylation, urea formation, and Mannich reaction. Screening of the library led to a quick development of the SAR and the significant improvement of PAR-1 activity.

  16. RSL3 and Erastin differentially regulate redox signaling to promote Smac mimetic-induced cell death

    PubMed Central

    Dächert, Jasmin; Schoeneberger, Hannah; Rohde, Katharina; Fulda, Simone

    2016-01-01

    Redox mechanisms play an important role in the control of various signaling pathways. Here, we report that Second mitochondrial activator of caspases (Smac) mimetic-induced cell death is regulated by redox signaling. We show that RSL3, a glutathione (GSH) peroxidase (GPX) 4 inhibitor, or Erastin, an inhibitor of the cystine/glutamate antiporter, cooperate with the Smac mimetic BV6 to induce reactive oxygen species (ROS)-dependent cell death in acute lymphoblastic leukemia (ALL) cells. Addition of the caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) fails to rescue ROS-induced cell death, demonstrating that RSL3/BV6- or Erastin/BV6-induced cell death occurs in a caspase-independent manner. Interestingly, the iron chelator Deferoxamine (DFO) significantly inhibits RSL3/BV6-induced cell death, whereas it is unable to rescue cell death by Erastin/BV6, showing that RSL3/BV6-, but not Erastin/BV6-mediated cell death depends on iron. ROS production is required for both RSL3/BV6- and Erastin/BV6-induced cell death, since the ROS scavenger α-tocopherol (α-Toc) rescues RSL3/BV6- and Erastin/BV6-induced cell death. By comparison, genetic or pharmacological inhibition of lipid peroxidation by GPX4 overexpression or ferrostatin (Fer)-1 significantly decreases RSL3/BV6-, but not Erastin/BV6-induced cell death, despite inhibition of lipid peroxidation upon exposure to RSL3/BV6 or Erastin/BV6. Of note, inhibition of lipid peroxidation by Fer-1 protects from RSL3/BV6-, but not from Erastin/BV6-stimulated ROS production, indicating that other forms of ROS besides lipophilic ROS occur during Erastin/BV6-induced cell death. Taken together, RSL3/BV6 and Erastin/BV6 differentially regulate redox signaling and cell death in ALL cells. While RSL3/BV6 cotreatment induces ferroptotic cell death, Erastin/BV6 stimulates oxidative cell death independently of iron. These findings have important implications for the therapeutic targeting of redox signaling to

  17. Inter-species extrapolation of pharmacokinetic data of three prostacyclin-mimetics.

    PubMed

    Hildebrand, M

    1994-11-01

    Cica-, eptalo- and iloprost are chemically and metabolically stabilized derivatives of prostacyclin which maintain the pharmacodynamic profile of the endogenous precursor. While iloprost is still subject to beta-oxidative degradation of the upper side chain, cicaprost is highly metabolically stable. Eptaloprost was synthesized to realize the pro-drug concept in PGI2-mimetics and was designed to be activated to cicaprost by single beta-oxidation. All three prostacyclin-mimetics were studied in various animal species (mouse, rat, rabbit, monkey, dog and pig) and in man to determine their pharmacokinetic profiles. Based upon this data, it was of interest whether an inter-species extrapolation of pharmacokinetic parameters can be performed to show the predictive value of animal experimentation. Allometric inter-species extrapolation is performed by modelling pharmacokinetic data (Y) as exponential functions (x) of species characteristics (e.g. body weight, W) as: Y = .aWx. For total clearance and volumes of distribution at steady state, a clear-cut correlation with x-values of 0.6-0.8 and 1.0-1.1 could be shown for all three compounds. For cicaprost, which was excreted unchanged in several species, renal and non-renal clearance was also mathematically scalable. Due to the use of different compartment models to describe plasma disposition, different sets of half-life data were obtained and could not be extrapolated reasonably. However, mean residence time showed a dependency on body weight with 0.25 as power function. In case of cicaprost, only the dog, which extensively metabolizes the compound, could not be enrolled in inter-species extrapolation. Excretion half-lives or residence times did not show a significant correlation to body weight or maximum life time potential. The present inter-species extrapolation showed a dependency from species body weight for model-independent pharmacokinetic data, e.g. clearance, volume of distribution at steady state and

  18. TrkB reduction exacerbates Alzheimer's disease-like signaling aberrations and memory deficits without affecting β-amyloidosis in 5XFAD mice.

    PubMed

    Devi, L; Ohno, M

    2015-05-05

    Accumulating evidence shows that brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) significantly decrease early in Alzheimer's disease (AD). However, it remains unclear whether BDNF/TrkB reductions may be mechanistically involved in the pathogenesis of AD. To address this question, we generated 5XFAD transgenic mice with heterozygous TrkB knockout (TrkB(+/-)·5XFAD), and tested the effects of TrkB reduction on AD-like features in this mouse model during an incipient stage that shows only modest amyloid-β (Aβ) pathology and retains normal mnemonic function. TrkB(+/-) reduction exacerbated memory declines in 5XFAD mice at 4-5 months of age as assessed by the hippocampus-dependent spontaneous alternation Y-maze task, while the memory performance was not affected in TrkB(+/-) mice. Meanwhile, TrkB(+/-)·5XFAD mice were normal in nest building, a widely used measure for social behavior, suggesting the memory-specific aggravation of AD-associated behavioral impairments. We found no difference between TrkB(+/-)·5XFAD and 5XFAD control mice in cerebral plaque loads, Aβ concentrations including total Aβ42 and soluble oligomers and β-amyloidogenic processing of amyloid precursor protein. Interestingly, reductions in hippocampal expression of AMPA/NMDA glutamate receptor subunits as well as impaired signaling pathways downstream to TrkB such as CREB (cAMP response element-binding protein) and Akt/GSK-3β (glycogen synthase kinase-3β) were observed in TrkB(+/-)·5XFAD mice but not in 5XFAD mice. Among these signaling aberrations, only Akt/GSK-3β dysfunction occurred in TrkB(+/-) mice, while others were synergistic consequences between TrkB reduction and subthreshold levels of Aβ in TrkB(+/-)·5XFAD mice. Collectively, our results indicate that reduced TrkB does not affect β-amyloidosis but exacerbates the manifestation of hippocampal mnemonic and signaling dysfunctions in early AD.

  19. Cysteamine Attenuates the Decreases in TrkB Protein Levels and the Anxiety/Depression-Like Behaviors in Mice Induced by Corticosterone Treatment

    PubMed Central

    Kutiyanawalla, Ammar; Terry, Alvin V.; Pillai, Anilkumar

    2011-01-01

    Objective Stress and glucocorticoid hormones, which are released into the circulation following stressful experiences, have been shown to contribute significantly to the manifestation of anxiety-like behaviors observed in many neuropsychiatric disorders. Brain-derived neurotrophic factor (BDNF) signaling through its receptor TrkB plays an important role in stress-mediated changes in structural as well as functional neuroplasticity. Studies designed to elucidate the mechanisms whereby TrkB signaling is regulated in chronic stress might provide valuable information for the development of new therapeutic strategies for several stress-related psychiatric disorders. Materials and Methods We examined the potential of cysteamine, a neuroprotective compound to attenuate anxiety and depression like behaviors in a mouse model of anxiety/depression induced by chronic corticosterone exposure. Results Cysteamine administration (150 mg/kg/day, through drinking water) for 21 days significantly ameliorated chronic corticosterone-induced decreases in TrkB protein levels in frontal cortex and hippocampus. Furthermore, cysteamine treatment reversed the anxiety and depression like behavioral abnormalities induced by chronic corticosterone treatment. Finally, mice deficient in TrkB, showed a reduced response to cysteamine in behavioral tests, suggesting that TrkB signaling plays an important role in the antidepressant effects of cysteamine. Conclusions The animal studies described here highlight the potential use of cysteamine as a novel therapeutic strategy for glucocorticoid-related symptoms of psychiatric disorders. PMID:22039440

  20. Cysteamine attenuates the decreases in TrkB protein levels and the anxiety/depression-like behaviors in mice induced by corticosterone treatment.

    PubMed

    Kutiyanawalla, Ammar; Terry, Alvin V; Pillai, Anilkumar

    2011-01-01

    Stress and glucocorticoid hormones, which are released into the circulation following stressful experiences, have been shown to contribute significantly to the manifestation of anxiety-like behaviors observed in many neuropsychiatric disorders. Brain-derived neurotrophic factor (BDNF) signaling through its receptor TrkB plays an important role in stress-mediated changes in structural as well as functional neuroplasticity. Studies designed to elucidate the mechanisms whereby TrkB signaling is regulated in chronic stress might provide valuable information for the development of new therapeutic strategies for several stress-related psychiatric disorders. We examined the potential of cysteamine, a neuroprotective compound to attenuate anxiety and depression like behaviors in a mouse model of anxiety/depression induced by chronic corticosterone exposure. Cysteamine administration (150 mg/kg/day, through drinking water) for 21 days significantly ameliorated chronic corticosterone-induced decreases in TrkB protein levels in frontal cortex and hippocampus. Furthermore, cysteamine treatment reversed the anxiety and depression like behavioral abnormalities induced by chronic corticosterone treatment. Finally, mice deficient in TrkB, showed a reduced response to cysteamine in behavioral tests, suggesting that TrkB signaling plays an important role in the antidepressant effects of cysteamine. The animal studies described here highlight the potential use of cysteamine as a novel therapeutic strategy for glucocorticoid-related symptoms of psychiatric disorders.

  1. Behavioral and transcriptome alterations in male and female mice with postnatal deletion of TrkB in dorsal striatal medium spiny neurons

    PubMed Central

    2013-01-01

    Background The high affinity tyrosine kinase receptor, TrkB, is the primary receptor for brain derived neurotrophic factor (BDNF) and plays an important role in development, maintenance and plasticity of the striatal output medium size spiny neuron. The striatal BDNF/TrkB system is thereby implicated in many physiologic and pathophysiologic processes, the latter including mood disorders, addiction, and Huntington’s disease. We crossed a mouse harboring a transgene directing cre-recombinase expression primarily to postnatal, dorsal striatal medium spiny neurons, to a mouse containing a floxed TrkB allele (fB) mouse designed for deletion of TrkB to determine its role in the adult striatum. Results We found that there were sexually dimorphic alterations in behaviors in response to stressful situations and drugs of abuse. Significant sex and/or genotype differences were found in the forced swim test of depression-like behaviors, anxiety-like behaviors on the elevated plus maze, and cocaine conditioned reward. Microarray analysis of dorsal striatum revealed significant dysregulation in individual and groups of genes that may contribute to the observed behavioral responses and in some cases, represent previously unidentified downstream targets of TrkB. Conclusions The data point to a set of behaviors and changes in gene expression following postnatal deletion of TrkB in the dorsal striatum distinct from those in other brain regions. PMID:24369067

  2. Road to exercise mimetics: targeting nuclear receptors in skeletal muscle.

    PubMed

    Fan, Weiwei; Atkins, Annette R; Yu, Ruth T; Downes, Michael; Evans, Ronald M

    2013-12-01

    Skeletal muscle is the largest organ in the human body and is the major site for energy expenditure. It exhibits remarkable plasticity in response to physiological stimuli such as exercise. Physical exercise remodels skeletal muscle and enhances its capability to burn calories, which has been shown to be beneficial for many clinical conditions including the metabolic syndrome and cancer. Nuclear receptors (NRs) comprise a class of transcription factors found only in metazoans that regulate major biological processes such as reproduction, development, and metabolism. Recent studies have demonstrated crucial roles for NRs and their co-regulators in the regulation of skeletal muscle energy metabolism and exercise-induced muscle remodeling. While nothing can fully replace exercise, development of exercise mimetics that enhance or even substitute for the beneficial effects of physical exercise would be of great benefit. The unique property of NRs that allows modulation by endogenous or synthetic ligands makes them bona fide therapeutic targets. In this review, we present an overview of the current understanding of the role of NRs and their co-regulators in skeletal muscle oxidative metabolism and summarize recent progress in the development of exercise mimetics that target NRs and their co-regulators.

  3. The mimetic repertoire of the spotted bowerbird Ptilonorhynchus maculatus

    NASA Astrophysics Data System (ADS)

    Kelley, Laura A.; Healy, Susan D.

    2011-06-01

    Although vocal mimicry in songbirds is well documented, little is known about the function of such mimicry. One possibility is that the mimic produces the vocalisations of predatory or aggressive species to deter potential predators or competitors. Alternatively, these sounds may be learned in error as a result of their acoustic properties such as structural simplicity. We determined the mimetic repertoires of a population of male spotted bowerbirds Ptilonorhynchus maculatus, a species that mimics predatory and aggressive species. Although male mimetic repertoires contained an overabundance of vocalisations produced by species that were generally aggressive, there was also a marked prevalence of mimicry of sounds that are associated with alarm such as predator calls, alarm calls and mobbing calls, irrespective of whether the species being mimicked was aggressive or not. We propose that it may be the alarming context in which these sounds are first heard that may lead both to their acquisition and to their later reproduction. We suggest that enhanced learning capability during acute stress may explain vocal mimicry in many species that mimic sounds associated with alarm.

  4. Mimetic butterflies support Wallace's model of sexual dimorphism.

    PubMed

    Kunte, Krushnamegh

    2008-07-22

    Theoretical and empirical observations generally support Darwin's view that sexual dimorphism evolves due to sexual selection on, and deviation in, exaggerated male traits. Wallace presented a radical alternative, which is largely untested, that sexual dimorphism results from naturally selected deviation in protective female coloration. This leads to the prediction that deviation in female rather than male phenotype causes sexual dimorphism. Here I test Wallace's model of sexual dimorphism by tracing the evolutionary history of Batesian mimicry-an example of naturally selected protective coloration-on a molecular phylogeny of Papilio butterflies. I show that sexual dimorphism in Papilio is significantly correlated with both female-limited Batesian mimicry, where females are mimetic and males are non-mimetic, and with the deviation of female wing colour patterns from the ancestral patterns conserved in males. Thus, Wallace's model largely explains sexual dimorphism in Papilio. This finding, along with indirect support from recent studies on birds and lizards, suggests that Wallace's model may be more widely useful in explaining sexual dimorphism. These results also highlight the contribution of naturally selected female traits in driving phenotypic divergence between species, instead of merely facilitating the divergence in male sexual traits as described by Darwin's model.

  5. Effects of canola and corn oil mimetic on Jurkat cells

    PubMed Central

    2011-01-01

    Background The Western diet is high in omega-6 fatty acids and low in omega-3 fatty acids. Canola oil contains a healthier omega 3 to omega 6 ratio than corn oil. Jurkat T leukemia cells were treated with free fatty acids mixtures in ratios mimicking that found in commercially available canola oil (7% α-linolenic, 30% linoleic, 54% oleic) or corn oil (59% linoleic, 24% oleic) to determine the cell survival or cell death and changes in expression levels of inflammatory cytokines and receptors following oil treatment. Methods Fatty acid uptake was assessed by gas chromatography. Cell survival and cell death were evaluated by cell cycle analyses, propidium-iodide staining, trypan blue exclusion and phosphatidylserine externalization. mRNA levels of inflammatory cytokines and receptors were assessed by RT-PCR. Results There was a significant difference in the lipid profiles of the cells after treatment. Differential action of the oils on inflammatory molecules, following treatment at non-cytotoxic levels, indicated that canola oil mimetic was anti-inflammatory whereas corn oil mimetic was pro-inflammatory. Significance These results indicate that use of canola oil in the diet instead of corn oil might be beneficial for diseases promoted by inflammation. PMID:21631947

  6. BSA-stabilized Au clusters as peroxidase mimetics for use in xanthine detection.

    PubMed

    Wang, Xian-Xiang; Wu, Qi; Shan, Zhi; Huang, Qian-Ming

    2011-04-15

    In this paper, we demonstrated that bovine serum albumin (BSA) stabilized Au clusters exhibited highly intrinsic peroxidase-like activity. Unlike nature enzymes, the BSA-Au clusters have strong robustness and can be used over a wide range of pH and temperature. Because of ultra-small size, good stability and high biocompatibility in water solution compare with other kinds of nanoparticles as peroxidase mimetics, such as Fe(3)O(4), FeS or graphene oxide, it is more competent for bioanalysis. Furthermore, we make use of the novel properties of BSA-Au clusters as peroxidase mimetics to detect H(2)O(2). The as-prepared BSA-Au clusters were used to catalyze the oxidation of a peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) by H(2)O(2) to the oxidized colored product, and which provides a colorimetric detection of H(2)O(2). As low as 2.0 × 10(-8)M H(2)O(2) could be detected with a linear range from 5.0 × 10(-7) to 2.0 × 10(-5)M via this method. More importantly, a sensitive and selective method for xanthine detection was developed using xanthine oxidase (XOD) and the as-prepared BSA-Au clusters. The detection limit of this assay for xanthine was 5 × 10(-7)M and the proposed method was successfully applied for the determination of xanthine in urine and human serum sample. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Inhibition of Salmonella enterica biofilm formation using small-molecule adenosine mimetics.

    PubMed

    Koopman, Jacob A; Marshall, Joanna M; Bhatiya, Aditi; Eguale, Tadesse; Kwiek, Jesse J; Gunn, John S

    2015-01-01

    Biofilms have been widely implicated in chronic infections and environmental persistence of Salmonella enterica, facilitating enhanced colonization of surfaces and increasing the ability of the bacteria to be transmitted to new hosts. Salmonella enterica serovar Typhi biofilm formation on gallstones from humans and mice enhances gallbladder colonization and bacterial shedding, while Salmonella enterica serovar Typhimurium biofilms facilitate long-term persistence in a number of environments important to food, medical, and farming industries. Salmonella regulates expression of many virulence- and biofilm-related processes using kinase-driven pathways. Kinases play pivotal roles in phosphorylation and energy transfer in cellular processes and possess an ATP-binding pocket required for their functions. Many other cellular proteins also require ATP for their activity. Here we test the hypothesis that pharmacological interference with ATP-requiring enzymes utilizing adenosine mimetic compounds would decrease or inhibit bacterial biofilm formation. Through the screening of a 3,000-member ATP mimetic library, we identified a single compound (compound 7955004) capable of significantly reducing biofilm formation by S. Typhimurium and S. Typhi. The compound was not bactericidal or bacteriostatic toward S. Typhimurium or cytotoxic to mammalian cells. An ATP-Sepharose affinity matrix technique was used to discover potential protein-binding targets of the compound and identified GroEL and DeoD. Compound 7955004 was screened against other known biofilm-forming bacterial species and was found to potently inhibit biofilms of Acinetobacter baumannii as well. The identification of a lead compound with biofilm-inhibiting capabilities toward Salmonella provides a potential new avenue of therapeutic intervention against Salmonella biofilm formation, with applicability to biofilms of other bacterial pathogens.

  8. A novel approach to oral apoA-I mimetic therapy[S

    PubMed Central

    Chattopadhyay, Arnab; Navab, Mohamad; Hough, Greg; Gao, Feng; Meriwether, David; Grijalva, Victor; Springstead, James R.; Palgnachari, Mayakonda N.; Namiri-Kalantari, Ryan; Su, Feng; Van Lenten, Brian J.; Wagner, Alan C.; Anantharamaiah, G. M.; Farias-Eisner, Robin; Reddy, Srinivasa T.; Fogelman, Alan M.

    2013-01-01

    Transgenic tomato plants were constructed with an empty vector (EV) or a vector expressing an apoA-I mimetic peptide, 6F. EV or 6F tomatoes were harvested, lyophilized, ground into powder, added to Western diet (WD) at 2.2% by weight, and fed to LDL receptor-null (LDLR−/−) mice at 45 mg/kg/day 6F. After 13 weeks, the percent of the aorta with lesions was 4.1 ± 4%, 3.3 ± 2.4%, and 1.9 ± 1.4% for WD, WD + EV, and WD + 6F, respectively (WD + 6F vs. WD, P = 0.0134; WD + 6F vs. WD + EV, P = 0.0386; WD + EV vs. WD, not significant). While body weight did not differ, plasma serum amyloid A (SAA), total cholesterol, triglycerides, and lysophosphatidic acid (LPA) levels were less in WD + 6F mice; P < 0.0295. HDL cholesterol and paroxonase-1 activity (PON) were higher in WD + 6F mice (P = 0.0055 and P = 0.0254, respectively), but not in WD + EV mice. Plasma SAA, total cholesterol, triglycerides, LPA, and 15-hydroxyeicosatetraenoic acid (HETE) levels positively correlated with lesions (P < 0.0001); HDL cholesterol and PON were inversely correlated (P < 0.0001). After feeding WD + 6F: i) intact 6F was detected in small intestine (but not in plasma); ii) small intestine LPA was decreased compared with WD + EV (P < 0.0469); and iii) small intestine LPA 18:2 positively correlated with the percent of the aorta with lesions (P < 0.0179). These data suggest that 6F acts in the small intestine and provides a novel approach to oral apoA-I mimetic therapy. PMID:23378594

  9. A Furan-Based Lewis-Y-(CD174)-Saccharide Mimetic Inhibits Endothelial Functions and In Vitro Angiogenesis.

    PubMed

    Sauer, Sandra; Meissner, Tobias; Moehler, Thomas

    2015-01-01

    Angiogenesis is a fundamental process underlying cancer progression and autoimmune disease. Lewis Y is known as a regulated glycan-structure supporting human endothelial function and angiogenesis. We hypothesize that Lewis Y based analogues interfere with Lewis Y mediated endothelial functions and angiogenesis. We therefore evaluated the ability of 3, 4-bis [(b-D-galactopyranosyl)osy]-methyl-furan (BGF) a furan-based Lewis-Y saccharide mimetic to inhibit human endothelial adhesion, migration and in vitro angiogenesis. The ability of BGF and additional furan-based saccharide-mimetics was investigated to inhibit adhesion and migration of human bone marrow endothelial cells (HBMEC). Influence of BGF was tested on a multicelluar in vitro - angiogenesis assay in the presence of VEGF. BGF significantly inhibited HBMEC adhesion and migration stimulated by TNF-alpha by up to 70%. The anti-adhesive effect of BGF was particularly evident when HBMEC adhesion and migration was tested on collagen as extracellular matrix with weaker effect when laminin and fibronectin were used as an extracellular matrix. BGF was ineffective when HBMEC were stimulated with VEGF. The inhibition of endothelial function translated into a significant inhibitory effect of BGF in the multicellular in vitro angiogenesis-assay. BGF reduced the angiogenesis index compared to the positive controls by 32%. We identified the ability of the furan-based Lewis Y saccharide mimetic BGF as a specific modulator of TNF-alpha activated endothelial function and in vitro angiogenesis. BGF and other related glycan analogues should further be explored for their ability to down modulate endothelial activation in TNF-alpha driven pathophysiologic conditions in autoimmune disease and cancer indications.

  10. MET-Independent Lung Cancer Cells Evading EGFR Kinase Inhibitors are Therapeutically Susceptible to BH3 Mimetic Agents

    PubMed Central

    Fan, Weiwen; Tang, Zhe; Yin, Lihong; Morrison, Bei; Hafez-Khayyata, Said; Fu, Pingfu; Huang, Honglian; Bagai, Rakesh; Jiang, Shan; Kresak, Adam; Howell, Scott; Vasanji, Amit; Flask, Chris A.; Halmos, Balazs; Koon, Henry; Ma, Patrick C.

    2011-01-01

    Targeted therapies for cancer are inherently limited by the inevitable recurrence of resistant disease after initial responses. To define early molecular changes within residual tumor cells that persist after treatment, we analyzed drug sensitive lung adenocarcinoma cell lines exposed to reversible or irreversible EGFR inhibitors, alone or in combination with MET kinase inhibitors, to characterize the adaptive response that engenders drug resistance. Tumor cells displaying early resistance exhibited dependence on MET-independent activation of BCL-2/BCL-XL survival signaling. Further, such cells displayed a quiescence-like state associated with greatly retarded cell proliferation and cytoskeletal functions that were readily reversed after withdrawal of targeted inhibitors. Findings were validated in a xenograft model, demonstrating BCL-2 induction and p-STAT3[Y705] activation within the residual tumor cells surviving the initial anti-tumor response to targeted therapies. Disrupting the mitochondrial BCL-2/BCL-XL antiapoptotic machinery in early survivor cells using BH3 mimetic agents such as ABT-737, or by dual RNAi-mediated knockdown of BCL-2/BCL-XL, was sufficient to eradicate the early resistant lung tumor cells evading targeted inhibitors. Similarly, in a xenograft model the preemptive co-treatment of lung tumor cells with an EGFR inhibitor and a BH3 mimetic eradicated early TKI-resistant evaders and ultimately achieved a more durable response with prolonged remission. Our findings prompt prospective clinical investigations using BH3-mimetics combined with targeted receptor kinase inhibitors to optimize and improve clinical outcomes in lung cancer treatment. PMID:21555370

  11. Administration of the TrkB receptor agonist 7,8-dihydroxyflavone prevents traumatic stress-induced spatial memory deficits and changes in synaptic plasticity.

    PubMed

    Sanz-García, Ancor; Knafo, Shira; Pereda-Pérez, Inmaculada; Esteban, José A; Venero, César; Armario, Antonio

    2016-09-01

    Post-traumatic stress disorder (PTSD) occurs after exposure to traumatic situations and it is characterized by cognitive deficits that include impaired explicit memory. The neurobiological bases of such PTSD-associated memory alterations are yet to be elucidated and no satisfactory treatment for them exists. To address this issue, we first studied whether a single exposure of young adult rats (60 days) to immobilization on boards (IMO), a putative model of PTSD, produces long-term behavioral effects (2-8 days) similar to those found in PTSD patients. Subsequently, we investigated whether the administration of the TrkB agonist 7,8-dihydroxyflavone (DHF) 8 h after stress (therapeutic window) ameliorated the PTSD-like effect of IMO and the associated changes in synaptic plasticity. A single IMO exposure induced a spatial memory impairment similar to that found in other animal models of PTSD or in PTSD patients. IMO also increased spine density and long-term potentiation (LTP) in the CA3-CA1 pathway. Significantly, DHF reverted both spatial memory impairment and the increase in LTP, while it produced no effect in the controls. These data provide novel insights into the possible neurobiological substrate for explicit memory impairment in PTSD patients, supporting the idea that the activation of the BDNF/TrkB pathway fulfils a protective role after severe stress. Administration of DHF in the aftermath of a traumatic experience might be relevant to prevent its long-term consequences. © 2016 Wiley Periodicals, Inc.

  12. Involvement of TrkB- and p75NTR-signaling pathways in two contrasting forms of long-lasting synaptic plasticity

    NASA Astrophysics Data System (ADS)

    Sakuragi, Shigeo; Tominaga-Yoshino, Keiko; Ogura, Akihiko

    2013-11-01

    The repetition of experience is often necessary to establish long-lasting memory. However, the cellular mechanisms underlying this repetition-dependent consolidation of memory remain unclear. We previously observed in organotypic slice cultures of the rodent hippocampus that repeated inductions of long-term potentiation (LTP) led to a slowly developing long-lasting synaptic enhancement coupled with synaptogenesis. We also reported that repeated inductions of long-term depression (LTD) produced a long-lasting synaptic suppression coupled with synapse elimination. We proposed these phenomena as useful in vitro models for analyzing repetition-dependent consolidation. Here, we hypothesized that the enhancement and suppression are mediated by the brain-derived neurotrophic factor (BDNF)-TrkB signaling pathway and the proBDNF-p75NTR pathway, respectively. When we masked the respective pathways, reversals of the enhancement and suppression resulted. These results suggest the alternative activation of the p75NTR pathway by BDNF under TrkB-masking conditions and of the TrkB pathway by proBDNF under p75NTR-masking conditions, thus supporting the aforementioned hypothesis.

  13. Metallosurfactant Ionogels in Imidazolium and Protic Ionic Liquids as Precursors To Synthesize Nanoceria as Catalase Mimetics for the Catalytic Decomposition of H2 O2.

    PubMed

    Wang, Xiaolin; Yang, Qiao; Cao, Yixue; Hao, Haibin; Zhou, Junhan; Hao, Jingcheng

    2016-12-05

    The gelation behavior of cationic surfactants with different counterions, Br(-) , [FeCl3 Br](-) , and [CeCl3 Br](-) , in imidazolium ionic liquids (ILs) and protic ethylammonium nitrate was investigated. Small-angle X-ray scattering measurements and freeze-fracture transmission electron microscopy observations revealed the lamellar phases of metallosurfactant ionogels. The characteristics of imidazolium ILs, including the size and type, have effects on metallosurfactant ionogel properties, such as transformation temperatures, interlayer spacing, and mechanical strength. Cubic fluorite structured cerium oxide nanoparticles (CeO2 NPs) were produced by using metallosurfactant ionogels as precursors. Cubic fluorite CeO2 exhibited good catalase mimetic activity toward H2 O2 to generate O2 , providing more multiple mimetic enzyme activities of CeO2 NPs for H2 O2 .

  14. Presenilin mediates neuroprotective functions of ephrinB and brain-derived neurotrophic factor and regulates ligand-induced internalization and metabolism of EphB2 and TrkB receptors.

    PubMed

    Barthet, Gael; Dunys, Julie; Shao, Zhiping; Xuan, Zhao; Ren, Yimin; Xu, Jindong; Arbez, Nicolas; Mauger, Gweltas; Bruban, Julien; Georgakopoulos, Anastasios; Shioi, Junichi; Robakis, Nikolaos K

    2013-02-01

    Activation of EphB receptors by ephrinB (efnB) ligands on neuronal cell surface regulates important functions, including neurite outgrowth, axonal guidance, and synaptic plasticity. Here, we show that efnB rescues primary cortical neuronal cultures from necrotic cell death induced by glutamate excitotoxicity and that this function depends on EphB receptors. Importantly, the neuroprotective function of the efnB/EphB system depends on presenilin 1 (PS1), a protein that plays crucial roles in Alzheimer's disease (AD) neurodegeneration. Furthermore, absence of one PS1 allele results in significantly decreased neuroprotection, indicating that both PS1 alleles are necessary for full expression of the neuroprotective activity of the efnB/EphB system. We also show that the ability of brain-derived neurotrophic factor (BDNF) to protect neuronal cultures from glutamate-induced cell death depends on PS1. Neuroprotective functions of both efnB and BDNF, however, were independent of γ-secretase activity. Absence of PS1 decreases cell surface expression of neuronal TrkB and EphB2 without affecting total cellular levels of the receptors. Furthermore, PS1-knockout neurons show defective ligand-dependent internalization and decreased ligand-induced degradation of TrkB and Eph receptors. Our data show that PS1 mediates the neuroprotective activities of efnB and BDNF against excitotoxicity and regulates surface expression and ligand-induced metabolism of their cognate receptors. Together, our observations indicate that PS1 promotes neuronal survival by regulating neuroprotective functions of ligand-receptor systems.

  15. The SMAC mimetic birinapant attenuates lipopolysaccharide-induced liver injury by inhibiting the tumor necrosis factor receptor-associated factor 3 degradation in Kupffer cells.

    PubMed

    Liu, Hongxiang; Liao, Rui; He, Kun; Zhu, Xiwen; Li, Peizhi; Gong, Jianping

    2017-03-09

    It was demonstrated that second mitochondria-derived activator of caspases (SMAC) mimetic inhibites tumor necrosis factor receptor-associated factor 3 (TRAF3) degradation and the mitogen-activated protein kinase (MAPK) signaling pathway activation induced by lipopolysaccharide (LPS) in vitro. However, the effect of Smac mimetic in vivo is not clear. The present study was to investigate the role of Smac mimetic in LPS-induced liver injury in mice and its possible mechanism. An animal model of LPS-induced liver injury was established by intraperitoneally injecting mice with 10mg/kg LPS pretreatment with or without Smac mimetic birinapant (30mg/kg body weight). Birinapant significantly improved the survival rate of endotoxemic mice (P<0.05) and attenuated LPS-induced liver pathologic damage and inflammatory response. IL-1 and TNF-α levels in the serum were markedly decreased in birinapant pretreatment mice compared with control mice (P<0.05).The cellular inhibitor of apoptosis protein 1 (cIAP1) expression in liver resident macrophage (Kupffer cells, KCs) was significantly decreased in the Birinapant group compared to the Vehicle group (P<0.05). At the same time, total TRAF3 protein abundance in KCs rapidly declined after LPS stimulation in the Vehicle group. However, it remained constant in the Birinapant group. Moreover, K48-linked polyubiquitination of TRAF3 in KCs was markedly impressed in the birinapant group compared with the control group. At last, the JNK and p38 MAPK activation in KCs was significantly inhibited by birinapant pretreatment (P<0.05). These results suggested that birinapant attenuated liver injury and improved survival rates in endotoxemic mice by inhibited the expression of cIAP1, degradation of TRAF3 and aviation of MAPK signaling pathway.

  16. Changes in expression of BDNF and its receptors TrkB and p75NTR in the hippocampus of a dog model of chronic alcoholism and abstinence.

    PubMed

    Xu, R; Duan, S R; Zhao, J W; Wang, C Y

    2015-08-01

    Chronic ethanol consumption can produce learning and memory deficits. Brain-derived neurotrophic factor (BDNF) and its receptors affect the pathogenesis of alcoholism. In this study, we examined the expression of BDNF, tropomyosin receptor kinase B (TrkB) and p75 neurotrophin receptor (p75NTR) in the hippocampus of a dog model of chronic alcoholism and abstinence. Twenty domestic dogs (9-10 months old, 15-20 kg; 10 males and 10 females) were obtained from Harbin Medical University. A stable alcoholism model was established through ad libitum feeding, and anti-alcohol drug treatment (Zhong Yao Jie Jiu Ling, the main ingredient was the stems of watermelon; developed in our laboratory), at low- and high-doses, was carried out. The Zhong Yao Jie Jiu Ling was effective for the alcoholism in dogs. The morphology of hippocampal neurons was evaluated using hematoxylin-eosin staining. The number and morphological features of BDNF, TrkB and p75NTR-positive neurons in the dentate gyrus (DG), and the CA1, CA3 and CA4 regions of the hippocampus were observed using immunohistochemistry. One-way ANOVA was used to determine differences in BDNF, TrkB and p75NTR expression. BDNF, TrkB and p75NTR-positive cells were mainly localized in the granular cell layer of the DG and in the pyramidal cell layer of the CA1, CA3 and CA4 regions (DG>CA1>CA3>CA4). Expression levels of both BDNF and TrkB were decreased in chronic alcoholism, and increased after abstinence. The CA4 region appeared to show the greatest differences. Changes in p75NTR expression were the opposite of those of BDNF and TrkB, with the greatest differences observed in the DG and CA4 regions.

  17. Neurotrophic factor small-molecule mimetics mediated neuroregeneration and synaptic repair: emerging therapeutic modality for Alzheimer's disease.

    PubMed

    Kazim, Syed Faraz; Iqbal, Khalid

    2016-07-11

    Alzheimer's disease (AD) is an incurable and debilitating chronic progressive neurodegenerative disorder which is the leading cause of dementia worldwide. AD is a heterogeneous and multifactorial disorder, histopathologically characterized by the presence of amyloid β (Aβ) plaques and neurofibrillary tangles composed of Aβ peptides and abnormally hyperphosphorylated tau protein, respectively. Independent of the various etiopathogenic mechanisms, neurodegeneration is a final common outcome of AD neuropathology. Synaptic loss is a better correlate of cognitive impairment in AD than Aβ or tau pathologies. Thus a highly promising therapeutic strategy for AD is to shift the balance from neurodegeneration to neuroregeneration and synaptic repair. Neurotrophic factors, by virtue of their neurogenic and neurotrophic activities, have potential for the treatment of AD. However, the clinical therapeutic usage of recombinant neurotrophic factors is limited because of the insurmountable hurdles of unfavorable pharmacokinetic properties, poor blood-brain barrier (BBB) permeability, and severe adverse effects. Neurotrophic factor small-molecule mimetics, in this context, represent a potential strategy to overcome these short comings, and have shown promise in preclinical studies. Neurotrophic factor small-molecule mimetics have been the focus of intense research in recent years for AD drug development. Here, we review the relevant literature regarding the therapeutic beneficial effect of neurotrophic factors in AD, and then discuss the recent status of research regarding the neurotrophic factor small-molecule mimetics as therapeutic candidates for AD. Lastly, we summarize the preclinical studies with a ciliary neurotrophic factor (CNTF) small-molecule peptide mimetic, Peptide 021 (P021). P021 is a neurogenic and neurotrophic compound which enhances dentate gyrus neurogenesis and memory processes via inhibiting leukemia inhibitory factor (LIF) signaling pathway and increasing

  18. Localization of TrkB and p75 receptors in peritoneal and deep infiltrating endometriosis: an immunohistochemical study.

    PubMed

    Dewanto, Agung; Dudas, Jozsef; Glueckert, Rudolf; Mechsner, Sylvia; Schrott-Fischer, Anneliese; Wildt, Ludwig; Seeber, Beata

    2016-08-12

    The roles of the neurotrophins NGF (Neurotrophic growth factor) and BDNF (brain-derived neurotrophic factor) in neuronal growth and development are already known. Meanwhile, the neurotrophin receptors TrkA (tropomyosin related kinase A), TrkB, and p75 are important for determining the fate of cells. In endometriosis, this complex system has not been fully elucidated yet. The aim of this study was to evaluate the expression and location of these neurotrophins and their receptors in peritoneal (PE) and deep infiltrating endometriotic (DIE) tissues and to measure and compare the density of nerve fibers in the disease subtypes. PE lesions (n = 20) and DIE lesions (n = 22) were immunostained and analyzed on serial slides with anti-BDNF, -NGF, -TrkA, -TrkB, -p75,-protein gene product 9.5 (PGP9.5, intact nerve fibers) and -tyrosine hydroxylase (TH, sympathetic nerve fibers) antibodies. There was an equally high percentage (greater than 75 %) of BDNF-positive immunostaining cells in both PE and DIE. TrkB (major BDNF receptor) and p75 showed a higher percentage of immunostaining cells in DIE compared to in PE in stroma only (p < 0.014, p < 0.027, respectively). Both gland and stroma of DIE lesions had a lower percentage of NGF-positive immunostaining cells compared to those in PE lesions (p < 0.01 and p < 0.01, respectively), but there was no significant reduction in immunostaining of TrkA in DIE lesions. There was no difference in the mean density of nerve fibers stained with PGP9.5 between PE (26.27 ± 17.32) and DIE (28.19 ± 33.15, p = 0.8). When we performed sub-group analysis, the density of nerves was significantly higher in the bowel DIE (mean 57.33 ± 43.9) than in PE (mean 26.27 ± 17.32, p < 0.01) and non-bowel DIE (mean 14.6. ± 8.6 p < 0.002). While the neurotrophin BDNF is equally present in PE and DIE, its receptors TrkB and p75 are more highly expressed in DIE and may have a potential role in the

  19. Modification of biomaterials surface by mimetic cell membrane to improve biocompatibility

    NASA Astrophysics Data System (ADS)

    Zhou, Lei; Tan, Guo-Xin; Ning, Cheng-Yun

    2014-12-01

    Modification of biomaterials surface by mimetic cell membrane for improving biocompatibility, to imitate the excellent biological and physiological properties of the natural cell membrane, is an important research area in materials science. Numerous studies have been attempted to construct a mimetic cell membrane biointerface composed of phosphorylcholine (PC)-containing polymers or other phospholipid analogues on biomaterials surface. PC-containing biointerfaces show outstanding characteristics, especially in biological aspects such as blood compatibility and antifouling property. In this mini-review, the strategies of membrane mimetic modification of biomaterials and their antifouling applications are summarized.

  20. Protection against the synaptic targeting and toxicity of Alzheimer's-associated Aβ oligomers by insulin mimetic chiro-inositols

    PubMed Central

    Pitt, Jason; Thorner, Michael; Brautigan, David; Larner, Joseph; Klein, William L.

    2013-01-01

    Alzheimer's disease (AD) is a progressive dementia that correlates highly with synapse loss. This loss appears due to the synaptic accumulation of toxic Aβ oligomers (ADDLs), which damages synapse structure and function. Although it has been reported that oligomer binding and toxicity can be prevented by stimulation of neuronal insulin signaling with PPARγ agonists, these agonists have problematic side effects. We therefore investigated the therapeutic potential of chiro-inositols, insulin-sensitizing compounds safe for human consumption. Chiro-inositols have been studied extensively for treatment of diseases associated with peripheral insulin resistance, but their insulin mimetic function in memory-relevant central nervous system (CNS) cells is unknown. Here we demonstrate that mature cultures of hippocampal neurons respond to d-chiro-inositol (DCI), pinitol (3-O-methyl DCI), and the inositol glycan INS-2 (pinitol β-1-4 galactosamine) with increased phosphorylation in key upstream components in the insulin-signaling pathway (insulin receptor, insulin receptor substrate-1, and Akt). Consistent with insulin stimulation, DCI treatment promotes rapid withdrawal of dendritic insulin receptors. With respect to neuroprotection, DCI greatly enhances the ability of insulin to prevent ADDL-induced synapse damage (EC50 of 90 nM). The mechanism comprises inhibition of oligomer binding at synapses and requires insulin/IGF signaling. DCI showed no effects on Aβ oligomerization. We propose that inositol glycans and DCI, a compound already established as safe for human consumption, have potential as AD therapeutics by protecting CNS synapses against Aβ oligomers through their insulin mimetic activity.—Pitt, J., Thorner, M., Brautigan, D., Larner, J., Klein, W. L. Protection against the synaptic targeting and toxicity of Alzheimer's-associated Aβ oligomers by insulin mimetic chiro-inositols. PMID:23073831

  1. TrkB Activators for the Treatment of Traumatic Vision Loss

    DTIC Science & Technology

    2015-10-01

    Figure 1. Nissl- stained (red) retinal cross sections stained of Thy1-CFP (green) mice 7 days after exposure to 48psi blast. Effect of HIOC, with...Publications 1. Lay press: none 2. Peer-reviewed scientific journals: Setterholm, N.A., McDonald, F.E., Boatright, J.H., Iuvone, P.M.: Gram scale...Reprint of published paper: Setterholm et al., Gram -scale, chemoselective synthesis of N -[2-(5hydroxy-1H-indol-3-yl)ethyl]-2-oxopiperidine-3-carboxamide

  2. TrkB Activators for the Treatment of Traumatic Vision Loss

    DTIC Science & Technology

    2015-10-01

    reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions ...Figure 1. Nissl- stained (red) retinal cross sections stained of Thy1-CFP (green) mice 7 days after exposure to 48psi blast. Effect of HIOC, with...Publications 1. Lay press: none 2. Peer-reviewed scientific journals: Setterholm, N.A., McDonald, F.E., Boatright, J.H., Iuvone, P.M.: Gram scale

  3. TrkB Activators for the Treatment of Traumatic Vision Loss

    DTIC Science & Technology

    2013-10-01

    Mechanisms of Glaucoma Symposium. A manuscript is being prepared for submission as a technical brief. A B Figure 2. Optic nerve...at the International Society for Eye Research (ISER) Symposium on Molecular Mechanisms in Glaucoma on the new RGC cell death assay. A copy of the

  4. Distinct regulatory mechanisms of the human ferritin gene by hypoxia and hypoxia mimetic cobalt chloride at the transcriptional and post-transcriptional levels.

    PubMed

    Huang, Bo-Wen; Miyazawa, Masaki; Tsuji, Yoshiaki

    2014-12-01

    Cobalt chloride has been used as a hypoxia mimetic because it stabilizes hypoxia inducible factor-1α (HIF1-α) and activates gene transcription through a hypoxia responsive element (HRE). However, differences between hypoxia and hypoxia mimetic cobalt chloride in gene regulation remain elusive. Expression of ferritin, the major iron storage protein, is regulated at the transcriptional and posttranscriptional levels through DNA and RNA regulatory elements. Here we demonstrate that hypoxia and cobalt chloride regulate ferritin heavy chain (ferritin H) expression by two distinct mechanisms. Both hypoxia and cobalt chloride increased HIF1-α but a putative HRE in the human ferritin H gene was not activated. Instead, cobalt chloride but not hypoxia activated ferritin H transcription through an antioxidant responsive element (ARE), to which Nrf2 was recruited. Intriguingly, cobalt chloride downregulated ferritin H protein expression while it upregulated other ARE-regulated antioxidant genes in K562 cells. Further characterization demonstrated that cobalt chloride increased interaction between iron regulatory proteins (IRP1 and IRP2) and iron responsive element (IRE) in the 5'UTR of ferritin H mRNA, resulting in translational block of the accumulated ferritin H mRNA. In contrast, hypoxia had marginal effect on ferritin H transcription but increased its translation through decreased IRP1-IRE interaction. These results suggest that hypoxia and hypoxia mimetic cobalt chloride employ distinct regulatory mechanisms through the interplay between DNA and mRNA elements at the transcriptional and post-transcriptional levels. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Distinct Regulatory Mechanisms of the Human Ferritin Gene by Hypoxia and Hypoxia Mimetic Cobalt Chloride at the Transcriptional and Post-transcriptional Levels

    PubMed Central

    Huang, Bo-Wen; Miyazawa, Masaki; Tsuji, Yoshiaki

    2014-01-01

    Cobalt chloride has been used as a hypoxia mimetic because it stabilizes hypoxia inducible factor-1α (HIF1-α) and activates gene transcription through a hypoxia responsive element (HRE). However, differences between hypoxia and hypoxia mimetic cobalt chloride in gene regulation remain elusive. Expression of ferritin, the major iron storage protein, is regulated at the transcriptional and posttranscriptional levels through DNA and RNA regulatory elements. Here we demonstrate that hypoxia and cobalt chloride regulate ferritin heavy chain (ferritin H) expression by two distinct mechanisms. Both hypoxia and cobalt chloride increased HIF1-α but a putative HRE in the human ferritin H gene was not activated. Instead, cobalt chloride but not hypoxia activated ferritin H transcription through an antioxidant responsive element (ARE), to which Nrf2 was recruited. Intriguingly, cobalt chloride downregulated ferritin H protein expression while upregulated other ARE-regulated antioxidant genes in K562 cells. Further characterization demonstrated that cobalt chloride increased interaction between iron regulatory proteins (IRP1 and IRP2) and iron responsive element (IRE) in the 5′UTR of ferritin H mRNA, resulting in translational block of the accumulated ferritin H mRNA. In contrast, hypoxia had marginal effect on ferritin H transcription but increased its translation through decreased IRP1-IRE interaction. These results suggest that hypoxia and hypoxia mimetic cobalt chloride employ distinct regulatory mechanisms through the interplay between DNA and mRNA elements at the transcriptional and post-transcriptional levels. PMID:25172425

  6. SMAC mimetic (JP1201) sensitizes non-small cell lung cancers to multiple chemotherapy agents in an IAP dependent but TNFα independent manner

    PubMed Central

    Greer, Rachel M.; Peyton, Michael; Larsen, Jill E.; Girard, Luc; Xie, Yang; Gazdar, Adi; Harran, Patrick; Wang, Lai; Brekken, Rolf A.; Wang, Xiaodong; Minna, John D.

    2012-01-01

    Inhibitors of apoptosis proteins (IAPs) are key regulators of apoptosis and are inhibited by the second mitocondrial activator of caspases (SMAC). Previously, a small subset of TNFα-expressing non-small cell lung cancers (NSCLCs) was found to be sensitive to SMAC mimetics alone. In this study we determined if a SMAC mimetic (JP1201) could sensitize non-responsive NSCLC cell lines to standard chemotherapy. We found that JP1201 sensitized NSCLCs to doxorubicin, erlotinib, gemcitabine, paclitaxel, vinorelbine, and the combination of carboplatin with paclitaxel in a synergistic manner at clinically achievable drug concentrations. Sensitization did not occur with platinum alone. Furthermore, sensitization was specific for tumor compared to normal lung epithelial cells, increased in NSCLCs harvested after chemotherapy treatment, and did not induce TNFα secretion. Sensitization also was enhanced in vivo with increased tumor inhibition and increased survival of mice carrying xenografts. These effects were accompanied by caspase 3, 4, and 9 activation, indicating that both mitochondrial and ER stress-induced apoptotic pathways are activated by the combination of vinorelbine and JP1201. Chemotherapies that induce cell death through the mitochondrial pathway required only inhibition of XIAP for sensitization, while chemotherapies that induce cell death through multiple apoptotic pathways required inhibition of cIAP1, cIAP2, and XIAP. Therefore, the data suggest that IAP-targeted therapy using a SMAC mimetic provides a new therapeutic strategy for synergistic sensitization of NSCLCs to standard chemotherapy agents, which appears to occur independently of TNFα secretion. PMID:22049529

  7. Co-targeting of Bcl-2 and mTOR pathway triggers synergistic apoptosis in BH3 mimetics resistant acute lymphoblastic leukemia

    PubMed Central

    Allegretti, Matteo; Mirabilii, Simone; Licchetta, Roberto; Bergamo, Paola; Rinaldo, Cinzia; Zeuner, Ann; Foà, Robin; Milella, Michele; McCubrey, James A.; Martelli, Alberto M.; Tafuri, Agostino

    2015-01-01

    Several chemo-resistance mechanisms including the Bcl-2 protein family overexpression and constitutive activation of the PI3K/Akt/mTOR signaling have been documented in acute lymphoblastic leukemia (ALL), encouraging targeted approaches to circumvent this clinical problem. Here we analyzed the activity of the BH3 mimetic ABT-737 in ALL, exploring the synergistic effects with the mTOR inhibitor CCI-779 on ABT-737 resistant cells. We showed that a low Mcl-1/Bcl-2 plus Bcl-xL protein ratio determined ABT-737 responsiveness. ABT-737 exposure further decreased Mcl-1, inducing apoptosis on sensitive models and primary samples, while not affecting resistant cells. Co-inhibition of Bcl-2 and the mTOR pathway resulted cytotoxic on ABT-737 resistant models, by downregulating mTORC1 activity and Mcl-1 in a proteasome-independent manner. Although Mcl-1 seemed to be critical, ectopic modulation did not correlate with apoptosis changes. Importantly, dual targeting proved effective on ABT-737 resistant samples, showing additive/synergistic effects. Together, our results show the efficacy of BH3 mimetics as single agent in the majority of the ALL samples and demonstrate that resistance to ABT-737 mostly correlated with Mcl-1 overexpression. Co-targeting of the Bcl-2 protein family and mTOR pathway enhanced drug-induced cytotoxicity by suppressing Mcl-1, providing a novel therapeutic approach to overcome BH3 mimetics resistance in ALL. PMID:26392332

  8. TrkB overexpression in mice buffers against memory deficits and depression-like behavior but not all anxiety- and stress-related symptoms induced by developmental exposure to methylmercury

    PubMed Central

    Karpova, Nina N.; Lindholm, Jesse Saku Olavi; Kulesskaya, Natalia; Onishchenko, Natalia; Vahter, Marie; Popova, Dina; Ceccatelli, Sandra; Castrén, Eero

    2014-01-01

    Developmental exposure to low dose of methylmercury (MeHg) has a long-lasting effect on memory and attention deficits in humans, as well as cognitive performance, depression-like behavior and the hippocampal levels of the brain-derived neurotrophic factor (Bdnf)in mice. The Bdnf receptor TrkB is a key player of Bdnf signaling. Using transgenic animals, here we analyzed the effect of the full-length TrkB overexpression (TK+) on behavior impairments induced by perinatal MeHg. TK overexpression in the MeHg-exposed mice enhanced generalized anxiety and cue memory in the fear conditioning (FC) test. Early exposure to MeHg induced deficits in reversal spatial memory in the Morris water maze (MWM) test and depression-like behavior in the forced swim test (FST) in only wild-type (WT) mice but did not affect these parameters in TK+ mice. These changes were associated with TK+ effect on the increase in Bdnf 2, 3, 4 and 6 transcription in the hippocampus as well as with interaction of TK+ and MeHg factors for Bdnf 1, 9a and truncated TrkB.T1 transcripts in the prefrontal cortex. However, the MeHg-induced anxiety-like behavior in the elevated plus maze (EPM) and open field (OF) tests was ameliorated by TK+ background only in the OF test. Moreover, TK overexpression in the MeHg mice did not prevent significant stress-induced weight loss during the period of adaptation to individual housing in metabolic cages. These TK genotype-independent changes were primarily accompanied by the MeHg-induced hippocampal deficits in the activity-dependent Bdnf 1, 4 and 9a variants, TrkB.T1, and transcripts for important antioxidant enzymes glyoxalases Glo1 and Glo2 and glutathione reductase Gsr. Our data suggest a role of full-length TrkB in buffering against memory deficits and depression-like behavior in the MeHg mice but propose the involvement of additional pathways, such as the antioxidant system or TrkB.T1 signaling, in stress- or anxiety-related responses induced by developmental Me

  9. Extracellular matrix-mimetic adhesive biomaterials for bone repair

    PubMed Central

    Shekaran, Asha; García, Andrés J.

    2010-01-01

    Limited osseointegration of current orthopaedic biomaterials contributes to the failure of implants such as arthroplasties, bone screws and bone grafts, which present a large socioeconomic cost within the United States. These implant failures underscore the need for biomimetic approaches that modulate host cell-implant material responses to enhance implant osseointegration and bone formation. Bioinspired strategies have included functionalizing implants with ECM proteins or ECM-derived peptides or protein fragments which engage integrins and direct osteoblast adhesion and differentiation. This review discusses 1) bone ECM composition and key integrins implicated in osteogenic differentiation, 2) the use of implants functionalized with ECM-mimetic peptides/protein fragments, and 3) growth-factor derived peptides to promote the mechanical fixation of implants to bone and to enhance bone healing within large defects. PMID:21105174

  10. Resveratrol as a calorie restriction mimetic: therapeutic implications

    PubMed Central

    Chung, Jay H.; Manganiello, Vincent; Dyck, Jason R.B.

    2012-01-01

    It is widely believed that calorie restriction (CR) can extend the lifespan of model organisms and protect against aging-related diseases. A potential CR mimetic is resveratrol, which may have beneficial effects against numerous diseases such as type 2 diabetes, cardiovascular diseases, and cancer in tissue culture and animal models. However, resveratrol in its current form is not ideal as therapy, because even at very high doses it has modest efficacy and many downstream effects. Identifying the cellular targets responsible for the effects of resveratrol and developing target-specific therapies will be helpful in increasing the efficacy of this drug without increasing its potential adverse effects. A recent discovery suggests that the metabolic effects of resveratrol may be mediated by inhibiting cAMP phosphodiesterases (PDEs), particularly PDE4. Here, we review the current literature on the metabolic and cardiovascular effects of resveratrol and attempt to shed light on the controversies surrounding its action. PMID:22885100

  11. A multilevel multiscale mimetic method for an anisotropic infiltration problem

    SciTech Connect

    Lipnikov, Konstantin; Moulton, David; Svyatskiy, Daniil

    2009-01-01

    Modeling of multiphase flow and transport in highly heterogeneous porous media must capture a broad range of coupled spatial and temporal scales. Recently, a hierarchical approach dubbed the Multilevel Multiscale Mimetic (M3) method, was developed to simulate two-phase flow in porous media. The M{sup 3} method is locally mass conserving at all levels in its hierarchy, it supports unstructured polygonal grids and full tensor permeabilities, and it can achieve large coarsening factors. In this work we consider infiltration of water into a two-dimensional layered medium. The grid is aligned with the layers but not the coordinate axes. We demonstrate that with an efficient temporal updating strategy for the coarsening parameters, fine-scale accuracy of prominent features in the flow is maintained by the M{sup 3} method.

  12. Self-assembly of fibronectin mimetic peptide-amphiphile nanofibers

    NASA Astrophysics Data System (ADS)

    Rexeisen, Emilie Lynn

    Many therapeutic strategies incorporate peptides into their designs to mimic the natural protein ligands found in vivo. A few examples are the short peptide sequences RGD and PHSRN that mimic the primary and synergy-binding domains of the extracellular matrix protein, fibronectin, which is recognized by the cell surface receptor, alpha5beta 1 integrin. Even though scaffold modification with biomimetic peptides remains one of the most promising approaches for tissue engineering, the use of these peptides in therapeutic tissue-engineered products and drug delivery systems available on the commercial market is limited because the peptides are not easily able to mimic the natural protein. The design of a peptide that can effectively target the alpha5beta1 integrin would greatly increase biomimetic scaffold therapeutic potential. A novel peptide containing both the RGD primary binding domain and PHSRN synergy-binding domain for fibronectin joined with the appropriate linker should bind alpha 5beta1 integrin more efficiently and lead to greater cell adhesion over RGD alone. Several fibronectin mimetic peptides were designed and coupled to dialkyl hydrocarbon tails to make peptide-amphiphiles. The peptides contained different linkers connecting the two binding domains and different spacers separating the hydrophobic tails from the hydrophilic headgroups. The peptide-amphiphiles were deposited on mica substrates using the Langmuir-Blodgett technique. Langmuir isotherms indicated that the peptide-amphiphiles that contained higher numbers of serine residues formed a more tightly packed monolayer, but the increased number of serines also made transferring the amphiphiles to the mica substrate more difficult. Atomic force microscopy (AFM) images of the bilayers showed that the headgroups might be bent, forming small divots in the surface. These divots may help expose the PHSRN synergy-binding domain. Parallel studies undertaken by fellow group members showed that human

  13. Taking toll: lipid A mimetics as adjuvants and immunomodulators.

    PubMed

    Persing, David H; Coler, Rhea N; Lacy, Michael J; Johnson, David A; Baldridge, Jory R; Hershberg, Robert M; Reed, Steven G

    2002-01-01

    Vaccine adjuvants based on the structure of lipid A, such as monophosphoryl lipid A (MLA), have proven to be safe and effective in inducing immune responses to heterologous proteins in animal and human vaccines. Recent work on the development of a recombinant vaccine for leishmaniasis has demonstrated that a clinical grade MLA formulation - MPL(R) adjuvant - is essential in the development of a protective response. Preliminary evidence suggests that MLA and a chemically distinct family of lipid A mimetics - the aminoalkyl glucosaminide 4-phosphates - act on Toll-like receptor 4 (TLR4). As TLR4 agonists, they have potent immunomodulatory effects when used both as vaccine adjuvants and as stand-alone products. Novel approaches to vaccine development could benefit from taking full advantage of the effects of these compounds on innate and adaptive responses.

  14. Genes controlling mimetic colour pattern variation in butterflies.

    PubMed

    Nadeau, Nicola J

    2016-10-01

    Butterfly wing patterns are made up of arrays of coloured scales. There are two genera in which within-species variation in wing patterning is common and has been investigated at the molecular level, Heliconius and Papilio. Both of these species have mimetic relationships with other butterfly species that increase their protection from predators. Heliconius have a 'tool-kit' of five genetic loci that control colour pattern, three of which have been identified at the gene level, and which have been repeatedly used to modify colour pattern by different species in the genus. By contrast, the three Papilio species that have been investigated each have different genetic mechanisms controlling their polymorphic wing patterns.

  15. Ancient homology underlies adaptive mimetic diversity across butterflies

    PubMed Central

    Gallant, Jason R.; Imhoff, Vance E.; Martin, Arnaud; Savage, Wesley K.; Chamberlain, Nicola L.; Pote, Ben L.; Peterson, Chelsea; Smith, Gabriella E.; Evans, Benjamin; Reed, Robert D.; Kronforst, Marcus R.; Mullen, Sean P.

    2014-01-01

    Convergent evolution provides a rare, natural experiment with which to test the predictability of adaptation at the molecular level. Little is known about the molecular basis of convergence over macro-evolutionary timescales. Here we use a combination of positional cloning, population genomic resequencing, association mapping and developmental data to demonstrate that positionally orthologous nucleotide variants in the upstream region of the same gene, WntA, are responsible for parallel mimetic variation in two butterfly lineages that diverged >65 million years ago. Furthermore, characterization of spatial patterns of WntA expression during development suggests that alternative regulatory mechanisms underlie wing pattern variation in each system. Taken together, our results reveal a strikingly predictable molecular basis for phenotypic convergence over deep evolutionary time. PMID:25198507

  16. A Bak-dependent mitochondrial amplification step contributes to Smac mimetic/glucocorticoid-induced necroptosis.

    PubMed

    Rohde, Katharina; Kleinesudeik, Lara; Roesler, Stefanie; Löwe, Oliver; Heidler, Juliana; Schröder, Katrin; Wittig, Ilka; Dröse, Stefan; Fulda, Simone

    2017-01-01

    Necroptosis is a form of programmed cell death that critically depends on RIP3 and MLKL. However, the contribution of mitochondria to necroptosis is still poorly understood. In the present study, we discovered that mitochondrial perturbations play a critical role in Smac mimetic/Dexamethasone (Dexa)-induced necroptosis independently of death receptor ligands. We demonstrate that the Smac mimetic BV6 and Dexa cooperate to trigger necroptotic cell death in acute lymphoblastic leukemia (ALL) cells that are deficient in caspase activation due to absent caspase-8 expression or pharmacological inhibition by the caspase inhibitor zVAD.fmk, since genetic silencing or pharmacological inhibition of RIP3 or MLKL significantly rescue BV6/Dexa-induced necroptosis. In addition, RIP3 or MLKL knockout mouse embryonic fibroblasts (MEFs) are protected from BV6/Dexa/zVAD.fmk-induced cell death. In contrast, antagonistic antibodies against the death receptor ligands TNFα, TRAIL or CD95 ligand fail to rescue BV6/Dexa-triggered cell death. Kinetic studies revealed that prior to cell death BV6/Dexa treatment causes hyperpolarization of the mitochondrial membrane potential (MMP) followed by loss of MMP, reactive oxygen species (ROS) production, Bak activation and disruption of mitochondrial respiration. Importantly, knockdown of Bak significantly reduces BV6/Dexa-induced loss of MMP and delays cell death, but not ROS production, whereas ROS scavengers attenuate Bak activation, indicating that ROS production occurs upstream of BV6/Dexa-mediated Bak activation. Consistently, BV6/Dexa treatment causes oxidative thiol modifications of Bak protein. Intriguingly, knockdown or knockout of RIP3 or MLKL protect ALL cells or MEFs from BV6/Dexa-induced ROS production, Bak activation, drop of MMP and disruption of mitochondrial respiration, demonstrating that these mitochondrial events depend on RIP3 and MLKL. Thus, mitochondria might serve as an amplification step in BV6/Dexa-induced necroptosis

  17. CNTO 530 functions as a potent EPO mimetic via unique sustained effects on bone marrow proerythroblast pools.

    PubMed

    Sathyanarayana, Pradeep; Houde, Estelle; Marshall, Deborah; Volk, Amy; Makropoulos, Dorie; Emerson, Christine; Pradeep, Anamika; Bugelski, Peter J; Wojchowski, Don M

    2009-05-14

    Anemia as associated with numerous clinical conditions can be debilitating, but frequently can be treated via administration of epoetin-alfa, darbepoietin-alfa, or methoxy-PEG epoetin-beta. Despite the complexity of EPO-EPO receptor interactions, the development of interesting EPO mimetic peptides (EMPs) also has been possible. CNTO 530 is one such novel MIMETIBODY Fc-domain dimeric EMP fusion protein. In a mouse model, single-dose CNTO 530 (unlike epoetin-alfa or darbepoietin-alfa) bolstered red cell production for up to 1 month. In 5-fluorouracil and carboplatin-paclitaxel models, CNTO 530 also protected against anemia with unique efficiency. These actions were not fully accounted for by half-life estimates, and CNTO 530 signaling events therefore were studied. Within primary bone marrow erythroblasts, kinetics of STAT5, ERK, and AKT activation were similar for CNTO 530 and epoetin-alfa. p70S6K activation by CNTO 530, however, was selectively sustained. In vivo, CNTO 530 uniquely stimulated the enhanced formation of PODXL(high)CD71(high) (pro)erythroblasts at frequencies multifold above epoetin-alfa or darbepoietin-alfa. CNTO 530 moreover supported the sustained expansion of a bone marrow-resident Kit(neg)CD71(high)Ter119(neg) progenitor pool. Based on these distinct erythropoietic and EPOR signaling properties, CNTO 530 holds excellent promise as a new EPO mimetic.

  18. CNTO 530 functions as a potent EPO mimetic via unique sustained effects on bone marrow proerythroblast pools

    PubMed Central

    Sathyanarayana, Pradeep; Houde, Estelle; Marshall, Deborah; Volk, Amy; Makropoulos, Dorie; Emerson, Christine; Pradeep, Anamika; Bugelski, Peter J.

    2009-01-01

    Anemia as associated with numerous clinical conditions can be debilitating, but frequently can be treated via administration of epoetin-alfa, darbepoietin-alfa, or methoxy-PEG epoetin-beta. Despite the complexity of EPO-EPO receptor interactions, the development of interesting EPO mimetic peptides (EMPs) also has been possible. CNTO 530 is one such novel MIMETIBODY Fc-domain dimeric EMP fusion protein. In a mouse model, single-dose CNTO 530 (unlike epoetin-alfa or darbepoietin-alfa) bolstered red cell production for up to 1 month. In 5-fluorouracil and carboplatin-paclitaxel models, CNTO 530 also protected against anemia with unique efficiency. These actions were not fully accounted for by half-life estimates, and CNTO 530 signaling events therefore were studied. Within primary bone marrow erythroblasts, kinetics of STAT5, ERK, and AKT activation were similar for CNTO 530 and epoetin-alfa. p70S6K activation by CNTO 530, however, was selectively sustained. In vivo, CNTO 530 uniquely stimulated the enhanced formation of PODXLhighCD71high (pro)erythroblasts at frequencies multifold above epoetin-alfa or darbepoietin-alfa. CNTO 530 moreover supported the sustained expansion of a bone marrow–resident KitnegCD71highTer119neg progenitor pool. Based on these distinct erythropoietic and EPOR signaling properties, CNTO 530 holds excellent promise as a new EPO mimetic. PMID:19264917

  19. Effect of Vanadyl Rosiglitazone, a New Insulin-Mimetic Vanadium Complexes, on Glucose Homeostasis of Diabetic Mice.

    PubMed

    Jiang, Pingzhe; Dong, Zhen; Ma, Baicheng; Ni, Zaizhong; Duan, Huikun; Li, Xiaodan; Wang, Bin; Ma, Xiaofeng; Wei, Qian; Ji, Xiangzhen; Li, Minggang

    2016-11-01

    Diabetes has been cited as the most challenging health problem in the twenty-first century. Accordingly, it is urgent to develop a new type of efficient and low-toxic antidiabetic medication. Since vanadium compounds have insulin-mimetic and potential hypoglycemic activities for type 1 and type 2 diabetes, a new trend has been developed using vanadium and organic ligands to form a new compound in order to increase the intestinal absorption and reduce the toxicity of vanadium compound. In the current investigation, a new organic vanadium compounds, vanadyl rosiglitazone, was synthesized and determined by infrared spectra. Vanadyl rosiglitazone and three other organic vanadium compounds were administered to the diabetic mice through oral administration for 5 weeks. The results of mouse model test indicated that vanadyl rosiglitazone could regulate the blood glucose level and relieve the symptoms of polydipsia, polyphagia, polyuria, and weight loss without side effects and was more effective than the other three organic vanadium compounds including vanadyl trehalose, vanadyl metformin, and vanadyl quercetin. The study indicated that vanadyl rosiglitazone presents insulin-mimetic activities, and it will be a good potential candidate for the development of a new type of oral drug for type 2 diabetes.

  20. Female preferences drive the evolution of mimetic accuracy in male sexual displays.

    PubMed

    Coleman, Seth William; Patricelli, Gail Lisa; Coyle, Brian; Siani, Jennifer; Borgia, Gerald

    2007-10-22

    Males in many bird species mimic the vocalizations of other species during sexual displays, but the evolutionary and functional significance of interspecific vocal mimicry is unclear. Here we use spectrographic cross-correlation to compare mimetic calls produced by male satin bowerbirds (Ptilonorhynchus violaceus) in courtship with calls from several model species. We show that the accuracy of vocal mimicry and the number of model species mimicked are both independently related to male mating success. Multivariate analyses revealed that these mimetic traits were better predictors of male mating success than other male display traits previously shown to be important for male mating success. We suggest that preference-driven mimetic accuracy may be a widespread occurrence, and that mimetic accuracy may provide females with important information about male quality. Our findings support an alternative hypothesis to help explain a common element of male sexual displays.

  1. Design and synthesis of type-III mimetics of ShK toxin

    NASA Astrophysics Data System (ADS)

    Baell, Jonathan B.; Harvey, Andrew J.; Norton, Raymond S.

    2002-04-01

    ShK toxin is a structurally defined, 35-residue polypeptide which blocks the voltage-gated Kv1.3 potass