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Sample records for apolipoprotein-e forms dimers

  1. Apolipoprotein E forms stable complexes with recombinant Alzheimer's disease beta-amyloid precursor protein.

    PubMed Central

    Haas, C; Cazorla, P; Miguel, C D; Valdivieso, F; Vázquez, J

    1997-01-01

    Apolipoprotein E (apoE), a protein genetically linked to the incidence of Alzheimer's disease, forms SDS-stable complexes in vitro with beta-amyloid peptide (Abeta), the primary component of senile plaques. In the present study, we investigated whether apoE was able to bind full-length Abeta precursor protein (APP). Using a maltose-binding-protein-APP fusion protein and human very-low-density lipoprotein (VLDL), we detected an interaction of apoE with APP that was inhibited by Abeta or anti-apoE antibody. Saturation-binding experiments indicated a single binding equilibrium with an apparent 1:1 stoichiometry and a dissociation constant of 15 nM. An interaction was also observed using apoE from cerebrospinal fluid or delipidated VLDL, as well as recombinant apoE. APP.apoE complexes were SDS-stable, and their formation was not inhibited by reducing conditions; however, they were dissociated by SDS under reducing conditions. ApoE.APP complexes formed high-molecular-mass aggregates, and competition experiments suggested that amino acids 14-23 of Abeta are responsible for complex-formation. Finally, no differences were found when studying the interaction of APP with apoE3 or apoE4. Taken together, our results demonstrate that apoE may form stable complexes with the Abeta moiety of APP with characteristics similar to those of complexes formed with isolated Abeta, and suggest the intriguing possibility that apoE-APP interactions may be pathologically relevant in vivo. PMID:9224643

  2. Conformational flexibility in the apolipoprotein E amino-terminal domain structure determined from three new crystal forms: implications for lipid binding.

    PubMed Central

    Segelke, B. W.; Forstner, M.; Knapp, M.; Trakhanov, S. D.; Parkin, S.; Newhouse, Y. M.; Bellamy, H. D.; Weisgraber, K. H.; Rupp, B.

    2000-01-01

    An amino-terminal fragment of human apolipoprotein E3 (residues 1-165) has been expressed and crystallized in three different crystal forms under similar crystallization conditions. One crystal form has nearly identical cell dimensions to the previously reported orthorhombic (P2(1)2(1)2(1)) crystal form of the amino-terminal 22 kDa fragment of apolipoprotein E (residues 1-191). A second orthorhombic crystal form (P2(1)2(1)2(1) with cell dimensions differing from the first form) and a trigonal (P3(1)21) crystal form were also characterized. The structures of the first orthorhombic and the trigonal form were determined by seleno-methionine multiwavelength anomalous dispersion, and the structure of the second orthorhombic form was determined by molecular replacement using the structure from the trigonal form as a search model. A combination of modern experimental and computational techniques provided high-quality electron-density maps, which revealed new features of the apolipoprotein E structure, including an unambiguously traced loop connecting helices 2 and 3 in the four-helix bundle and a number of multiconformation side chains. The three crystal forms contain a common intermolecular, antiparallel packing arrangement. The electrostatic complimentarity observed in this antiparallel packing resembles the interaction of apolipoprotein E with the monoclonal antibody 2E8 and the low density lipoprotein receptor. Superposition of the model structures from all three crystal forms reveals flexibility and pronounced kinks in helices near one end of the four-helix bundle. This mobility at one end of the molecule provides new insights into the structural changes in apolipoprotein E that occur with lipid association. PMID:10850798

  3. Apolipoprotein E genotype in schizophrenia

    SciTech Connect

    Joober, R.; Lal, S.; Bloom, D.; Benkelfat, C.

    1996-04-09

    We investigated the association between schizophrenia and the allelic polymorphism in the apolipoprotein E (Apo E) gene in 51 schizophrenic patients and 35 controls. The Apo E4 allele was equally represented in the schizophrenic group (16%) and the control group (20%) suggesting no association between schizophrenia and the Apo E4 allele. The apolipoprotein E (Apo E) is a polymorphic (E2, E3, and E4) lipoprotein involved in the transmembrane transport of cholesterol and is thought to play an important role in neuronal growth and in the central nervous system response to injury, particularly in the hippocampal region. Recent findings strongly suggest that the Apo E4 allele is associated with cognitive deficits in normal and pathological aging, e.g., Alzheimer`s disease. 5 refs., 1 tab.

  4. Role of apolipoprotein E in febrile convulsion.

    PubMed

    Giray, Ozlem; Ulgenalp, Ayfer; Bora, Elçin; Uran, Nedret; Yilmaz, Ebru; Unalp, Aycan; Erçal, Derya

    2008-10-01

    Apolipoprotein E is consistently associated with the progression of some common human neurodegenerative diseases, e.g., epilepsy. We hypothesized that genetic variations in the apolipoprotein E gene have implications for susceptibility to, and prognoses in, febrile convulsion, which plays an apparent role in the development of epilepsy. We used the polymerase chain reaction and restriction enzyme digestion to characterize variations of the apolipoprotein E gene. Sixty-nine patients with febrile convulsion (simple/complex) and a corresponding cohort of healthy patients (n = 75) were used. There was no significant difference in genotypic distribution and allelic frequencies of the apolipoprotein E gene between the febrile convulsion and control groups. Comparing subpopulations of the febrile convulsion group (patients with simple and complex febrile convulsion), we noted that no patients with the epsilon3/epsilon4 genotype had complex febrile convulsions. The apolipoprotein E epsilon3/epsilon4 genotype was more frequently seen in the simple febrile than in the complicated febrile convulsion group (9 versus 0 patients, respectively). The data indicate an association with the epsilon3/epsilon4 genotype of the apolipoprotein E gene with a milder phenotype. Although apolipoprotein E4 is not a vulnerability factor regarding febrile convulsions, it seems effective in regard to prognoses.

  5. Apolipoprotein E: the resilience gene.

    PubMed

    James, Lisa M; Engdahl, Brian E; Georgopoulos, Apostolos P

    2017-03-15

    The apolipoprotein E (apoE) gene has been implicated in various conditions, most notably Alzheimer's disease and coronary artery disease. A predisposing role of the apoE4 isoform and a protective role of apoE2 isoform in those diseases have been documented. Here we investigated the role of apoE in resilience to trauma. Three hundred and forty-three US veterans were genotyped for apoE and were assessed for their lifetime trauma exposure (trauma score, T) and severity of posttraumatic stress disorder symptoms (PCL). The ratio PCL/T indicates sensitivity to trauma; hence, its inverse indicates resilience, R, to trauma. We found a significantly higher resilience in participants with apoE genotype containing the E2 allele (E2/2, E2/3) as compared to participants with the E4 allele (E4/4, E4/3). In addition, when the categorical apoE genotype was reexpressed as the number of cysteine residues per apoE mole (CysR/mole), a highly significant positive association was found between resilience and CysR/mole, such that resilience was systematically higher as the number of CysR/mole increased, from zero CysR/mole in E4/4 to four CysR/mole in E2/2. These findings demonstrate the protective role of the CysR/mole apoE in resilience to trauma: the more CysR/mole, the higher the resilience. Thus, they are in accord with other findings pointing to a generally protective role of increasing number of CysR/mole (from E4/4 to E2/2) in other diseases. However, unlike other conditions (e.g., Alzheimer's disease and coronary artery disease), resilience to trauma is not a disease but an adaptive response to trauma. Therefore, the effects of apoE seem to be more pervasive along the CysR/mole continuum, most probably reflecting underlying effects on brain synchronicity and its variability that we have documented previously (Leuthold et al., Exp Brain Res 226:525-536, 2013).

  6. Characterization of mAb dimers reveals predominant dimer forms common in therapeutic mAbs

    PubMed Central

    Plath, Friederike; Ringler, Philippe; Graff-Meyer, Alexandra; Stahlberg, Henning; Lauer, Matthias E.; Rufer, Arne C.; Graewert, Melissa A.; Svergun, Dmitri; Gellermann, Gerald; Finkler, Christof; Stracke, Jan O.; Koulov, Atanas; Schnaible, Volker

    2016-01-01

    ABSTRACT The formation of undesired high molecular weight species such as dimers is an important quality attribute for therapeutic monoclonal antibody formulations. Therefore, the thorough understanding of mAb dimerization and the detailed characterization mAb dimers is of great interest for future pharmaceutical development of therapeutic antibodies. In this work, we focused on the analyses of different mAb dimers regarding size, surface properties, chemical identity, overall structure and localization of possible dimerization sites. Dimer fractions of different mAbs were isolated to a satisfactory purity from bulk material and revealed 2 predominant overall structures, namely elongated and compact dimer forms. The elongated dimers displayed one dimerization site involving the tip of the Fab domain. Depending on the stress applied, these elongated dimers are connected either covalently or non-covalently. In contrast, the compact dimers exhibited non-covalent association. Several interaction points were detected for the compact dimers involving the hinge region or the base of the Fab domain. These results indicate that mAb dimer fractions are rather complex and may contain more than one kind of dimer. Nevertheless, the overall appearance of mAb dimers suggests the existence of 2 predominant dimeric structures, elongated and compact, which are commonly present in preparations of therapeutic mAbs. PMID:27031922

  7. Direct Transcriptional Effects of Apolipoprotein E

    PubMed Central

    Theendakara, Veena; Peters-Libeu, Clare A.; Spilman, Patricia; Poksay, Karen S.

    2016-01-01

    A major unanswered question in biology and medicine is the mechanism by which the product of the apolipoprotein E ε4 allele, the lipid-binding protein apolipoprotein E4 (ApoE4), plays a pivotal role in processes as disparate as Alzheimer's disease (AD; in which it is the single most important genetic risk factor), atherosclerotic cardiovascular disease, Lewy body dementia, hominid evolution, and inflammation. Using a combination of neural cell lines, skin fibroblasts from AD patients, and ApoE targeted replacement mouse brains, we show in the present report that ApoE4 undergoes nuclear translocation, binds double-stranded DNA with high affinity (low nanomolar), and functions as a transcription factor. Using chromatin immunoprecipitation and high-throughput DNA sequencing, our results indicate that the ApoE4 DNA binding sites include ∼1700 gene promoter regions. The genes associated with these promoters provide new insight into the mechanism by which AD risk is conferred by ApoE4, because they include genes associated with trophic support, programmed cell death, microtubule disassembly, synaptic function, aging, and insulin resistance, all processes that have been implicated in AD pathogenesis. SIGNIFICANCE STATEMENT This study shows for the first time that apolipoprotein E4 binds DNA with high affinity and that its binding sites include 1700 promoter regions that include genes associated with neurotrophins, programmed cell death, synaptic function, sirtuins and aging, and insulin resistance, all processes that have been implicated in Alzheimer's disease pathogenesis. PMID:26791201

  8. Apolipoprotein E Polymorphism in Tuberculosis Patients

    NASA Astrophysics Data System (ADS)

    Naserpour Farivar, Taghi; Sharifi Moud, Batool; Sargazi, Mansur; Moeenrezakhanlou, Alireza

    In this study, we aimed to determine the significance of association between Tuberculosis and apolipoprotein E polymorphism. The apolipoprotein E genotypes were assayed in 250 tuberculosis patients by polymerase chain reaction followed by enzymatic digestion with Hha I. The results were compared with the results of the same experiments on 250 sex and age matched control peoples. Present results showed that in studied populations, prevalence of E4 genotype was lower in controls than in patients (8 v. 13.2%; OR = 1.75, p<0.05) and prevalence of E3 genotype was high in controls than in patients (86 v.51%; OR = 0.17, p<0.05). Statistically significant difference was found between patients and controls with respect to ɛ2 allele frequencies, while ɛ2 allele frequency was found to be much less prevalent in controls (6%) than in patients (35.8%; OR = 8.72, p<0.05). Also, our study revealed that there is an association between apolipoprotein E genotypes and amplitude to tuberculosis in studied populations. However, large population-based studies are needed to understand the exact role played by the locus in causing the condition.

  9. Graded-index optical dimer formed by optical force.

    PubMed

    Akbarzadeh, Alireza; Koschny, Thomas; Kafesaki, Maria; Economou, Eleftherios N; Soukoulis, Costas M

    2016-05-30

    We propose an optical dimer formed from two spherical lenses bound by the pressure that light exerts on matter. With the help of the method of force tracing, we find the required graded-index profiles of the lenses for the existence of the dimer. We study the dynamics of the opto-mechanical interaction of lenses under the illumination of collimated light beams and quantitatively validate the performance of proposed dimer. We also examine the stability of dimer due to the lateral misalignments and we show how restoring forces bring the dimer into lateral equilibrium. The dimer can be employed in various practical applications such as optical manipulation, sensing and imaging.

  10. Smectic Phase Formed by DNA Dimers

    NASA Astrophysics Data System (ADS)

    Salamonczyk, Miroslaw; Gleeson, James; Jakli, Antal; Sprunt, Samuel; Dhont, Jan; Stiakakis, Emmanuel

    The rapidly expanding bio market is driving the development and characterization of new multifunctional materials. In particular, nucleic acids are under intense study for gene therapy, drug delivery and other bio-safe applications [1,2,3]. DNA is well-known to form a cholesteric nematic liquid crystal in its native form; however, much recent research has focused on self-assembly and mesomorphic behavior in concentrated solutions of short DNA helices [4]. Our work focuses on DNA dimers, consisting of 48 base-pair double-stranded helices connected by a 5 to 20 base flexible single strand, and suspended in a natural buffer. Depending on temperature, concentration and length of the flexible spacer, polarizing optical microscopy and small angle x-ray scattering reveal cholesteric nematic and, remarkably, smectic liquid crystalline phases. A model for smectic phase formation in this system will be presented. 1] J.-L. Lim et al., Int. J. of. Pharm. 490 (2015) 2652] D.-H. Kim et al., Nature Biotech. 23 (2005) 2223] K. Liu et al., Chem. Eur. J. 21 (2015) 48984] M. Nakata et al., Science 318 (2007) 1276 NSF DMR 1307674.

  11. Palmitoylated APP Forms Dimers, Cleaved by BACE1.

    PubMed

    Bhattacharyya, Raja; Fenn, Rebecca H; Barren, Cory; Tanzi, Rudolph E; Kovacs, Dora M

    2016-01-01

    A major rate-limiting step for Aβ generation and deposition in Alzheimer's disease brains is BACE1-mediated cleavage (β-cleavage) of the amyloid precursor protein (APP). We previously reported that APP undergoes palmitoylation at two cysteine residues (Cys186 and Cys187) in the E1-ectodomain. 8-10% of total APP is palmitoylated in vitro and in vivo. Palmitoylated APP (palAPP) shows greater preference for β-cleavage than total APP in detergent resistant lipid rafts. Protein palmitoylation is known to promote protein dimerization. Since dimerization of APP at its E1-ectodomain results in elevated BACE1-mediated cleavage of APP, we have now investigated whether palmitoylation of APP affects its dimerization and whether this leads to elevated β-cleavage of the protein. Here we report that over 90% of palAPP is dimerized while only ~20% of total APP forms dimers. PalAPP-dimers are predominantly cis-oriented while total APP dimerizes in both cis- and trans-orientation. PalAPP forms dimers 4.5-times more efficiently than total APP. Overexpression of the palmitoylating enzymes DHHC7 and DHHC21 that increase palAPP levels and Aβ release, also increased APP dimerization in cells. Conversely, inhibition of APP palmitoylation by pharmacological inhibitors reduced APP-dimerization in coimmunoprecipitation and FLIM/FRET assays. Finally, in vitro BACE1-activity assays demonstrate that palmitoylation-dependent dimerization of APP promotes β-cleavage of APP in lipid-rich detergent resistant cell membranes (DRMs), when compared to total APP. Most importantly, generation of sAPPβ-sAPPβ dimers is dependent on APP-palmitoylation while total sAPPβ generation is not. Since BACE1 shows preference for palAPP dimers over total APP, palAPP dimers may serve as novel targets for effective β-cleavage inhibitors of APP as opposed to BACE1 inhibitors.

  12. Palmitoylated APP Forms Dimers, Cleaved by BACE1

    PubMed Central

    Fenn, Rebecca H.; Barren, Cory; Tanzi, Rudolph E.; Kovacs, Dora M.

    2016-01-01

    A major rate-limiting step for Aβ generation and deposition in Alzheimer’s disease brains is BACE1-mediated cleavage (β-cleavage) of the amyloid precursor protein (APP). We previously reported that APP undergoes palmitoylation at two cysteine residues (Cys186 and Cys187) in the E1-ectodomain. 8–10% of total APP is palmitoylated in vitro and in vivo. Palmitoylated APP (palAPP) shows greater preference for β-cleavage than total APP in detergent resistant lipid rafts. Protein palmitoylation is known to promote protein dimerization. Since dimerization of APP at its E1-ectodomain results in elevated BACE1-mediated cleavage of APP, we have now investigated whether palmitoylation of APP affects its dimerization and whether this leads to elevated β-cleavage of the protein. Here we report that over 90% of palAPP is dimerized while only ~20% of total APP forms dimers. PalAPP-dimers are predominantly cis-oriented while total APP dimerizes in both cis- and trans-orientation. PalAPP forms dimers 4.5-times more efficiently than total APP. Overexpression of the palmitoylating enzymes DHHC7 and DHHC21 that increase palAPP levels and Aβ release, also increased APP dimerization in cells. Conversely, inhibition of APP palmitoylation by pharmacological inhibitors reduced APP-dimerization in coimmunoprecipitation and FLIM/FRET assays. Finally, in vitro BACE1-activity assays demonstrate that palmitoylation-dependent dimerization of APP promotes β-cleavage of APP in lipid-rich detergent resistant cell membranes (DRMs), when compared to total APP. Most importantly, generation of sAPPβ-sAPPβ dimers is dependent on APP-palmitoylation while total sAPPβ generation is not. Since BACE1 shows preference for palAPP dimers over total APP, palAPP dimers may serve as novel targets for effective β-cleavage inhibitors of APP as opposed to BACE1 inhibitors. PMID:27875558

  13. Role of apolipoprotein E in neurodegenerative diseases

    PubMed Central

    Giau, Vo Van; Bagyinszky, Eva; An, Seong Soo A; Kim, Sang Yun

    2015-01-01

    Apolipoprotein E (APOE) is a lipid-transport protein abundantly expressed in most neurons in the central nervous system. APOE-dependent alterations of the endocytic pathway can affect different functions. APOE binds to cell-surface receptors to deliver lipids and to the hydrophobic amyloid-β peptide, regulating amyloid-β aggregations and clearances in the brain. Several APOE isoforms with major structural differences were discovered and shown to influence the brain lipid transport, glucose metabolism, neuronal signaling, neuroinflammation, and mitochondrial function. This review will summarize the updated research progress on APOE functions and its role in Alzheimer’s disease, Parkinson’s disease, cardiovascular diseases, multiple sclerosis, type 2 diabetes mellitus, Type III hyperlipoproteinemia, vascular dementia, and ischemic stroke. Understanding the mutations in APOE, their structural properties, and their isoforms is important to determine its role in various diseases and to advance the development of therapeutic strategies. Targeting APOE may be a potential approach for diagnosis, risk assessment, prevention, and treatment of various neurodegenerative and cardiovascular diseases in humans. PMID:26213471

  14. Apolipoprotein E: Risk factor for Alzheimer disease

    SciTech Connect

    Tsai, M.S.; Thibodeau, S.N.; Tangalos, E.G.; Petersen, R.C.; Kokmen, E.; Smith, G.E.; Schaid, D.J.; Ivnik, R.J. )

    1994-04-01

    The apolipoprotein E gene (APOE) has three common alleles (E2, E3, and E4) that determine six genotypes in the general population. In this study, the authors examined 77 patients with late-onset Alzheimer disease (AD), along with an equal number of age- and sex-matched controls, for an association with the APOE-E4 allele. They show that the frequency of this allele among AD patients was significantly higher than that among the control population (.351 vs. .130, P = .000006). The genotype frequencies also differed between the two groups (P = .0002), with the APOE-E4/E3 genotype being the most common in the AD group and the APOE-E3/E3 being the most common in the control group. In the AD group, homozygosity for E4 was found in nine individuals, whereas none was found in the control group. The odds ratio for AD, when associated with one or two E4 alleles, was 4.6 (95% confidence interval [CI] 1.9-12.3), while the odds ratio for AD, when associated with heterozygosity for APOE-E4, was 3.6 (05% CI 1.5-9.8). Finally, the median age at onset among the AD patients decreased from 83 to 78 to 74 years as the number of APOE-E4 alleles increased from 0 to 1 to 2, respectively (test for trend, P = .001). The data, which are in agreement with recent reports, suggest that the APOE-E4 allele is associated with AD and that this allelic variant may be an important risk factor for susceptibility to AD in the general population. 30 refs., 5 tabs.

  15. Secreted CXCL12 (SDF-1) Forms Dimers under Physiologic Conditions

    PubMed Central

    Ray, Paramita; Lewin, Sarah A.; Mihalko, Laura Anne; Lesher-Perez, Sasha Cai; Takayama, Shuichi; Luker, Kathryn E.; Luker, Gary D.

    2015-01-01

    Chemokine CXCL12 signaling through receptors CXCR4 and CXCR7 has essential functions in development and underlies diseases including cancer, atherosclerosis, and autoimmunity. Chemokines may form homodimers that regulate receptor binding and signaling, but previous studies with synthetic CXCL12 have produced conflicting evidence for homodimerization. We used bioluminescence imaging with Gaussia luciferase fusions to investigate dimerization of CXCL12 secreted from mammalian cells. By column chromatography and Gaussia luciferase complementation, we established that CXCL12 was secreted from mammalian cells as both monomers and dimers. Secreted CXCL12 also formed homodimers in the extracellular space. Monomeric CXCL12 preferentially activated CXCR4 signaling through Gαi and AKT, while dimeric CXCL12 more effectively promoted recruitment of β-arrestin 2 to CXCR4 and chemotaxis of CXCR4-expressing breast cancer cells. We also showed that CXCR7 preferentially sequestered monomeric CXCL12 from the extracellular space and had minimal effects on dimeric CXCL12 in cell-based assays and an orthotopic tumor xenograft model of human breast cancer. These studies establish that CXCL12 secreted from mammalian cells forms homodimers under physiologic conditions. Since monomeric and dimeric CXCL12 have distinct effects on cell signaling and function, our results have important implications for ongoing efforts to target CXCL12 pathways for therapy. PMID:22142194

  16. 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

  17. Apolipoprotein E and its role in aging and survival.

    PubMed

    Bonomini, Francesca; Filippini, Francesca; Hayek, Tony; Aviram, Michael; Keidar, Shlomo; Rodella, Luigi F; Coleman, Raymond; Rezzani, Rita

    2010-02-01

    The study of biological aging has seen spectacular progress in the last decade and markers are increasingly employed for understanding physiological processes that change with age. Recently, it has been demonstrated that apolipoprotein E (apoE) has a major impact on longevity, but its mechanisms are still not fully understood. ApoE-deficient (E(o)) mice have proved to be a very popular model for studying spontaneous hypercholesterolemia and the subsequent development of atherosclerotic lesions, but only limited data are available with regard to aging and aging changes. We used this murine model to better characterize the involvement of apoE in aging and to evaluate its role in the maintenance of normal organ morphology. Our results show that E(0) mice at different ages (6, 12, 20 weeks old) developed age-dependent morphological and biochemical alterations, including fibrosis (newly formed collagen), pro-inflammatory cytokine (IL-6 and iNOS), lipofuscin accumulation, and decrease of antioxidant enzymes (superoxide dismutase and catalase) in several organs (kidney, liver and heart). It is significant that the observed degenerative findings in E(0) mice at different ages (6, 12, 20 weeks old) were not identified in control mice (C57BL), at 6, 12 and 20 weeks of age. Consequently, since these mice showed enzymatic and structural alterations, normally linked to the age, such as increase of lipofuscin, pro-inflammatory cytokines and decrease of antioxidant enzymes, we can conclude that apoE is a useful player in studies of longevity and age-related diseases, such as inflammatory status and atherosclerosis that are known risk factors for functional decline and early mortality. Moreover, it is possible that apoE may also play a role in other pathological conditions including, for example, cancer, rheumatoid arthritis and macular degeneration.

  18. Plasmon excitations in the dimers formed by atom chains

    NASA Astrophysics Data System (ADS)

    Xue, Hong-jie; Hao, Da-peng; Zhang, Ming; Wang, Xiao-mei

    2017-02-01

    Based on the linear response theory in the random-phase approximation and the free-electron gas model, we study the plasmon excitations in the dimers formed by atom chains. With the help of energy absorption spectrum and charge distribution, the evolutions of longitudinal and transverse plasmon, and the effect of the system parameters such as size, atomic separation and electron filling on plasmon are obtained. In addition, the dipole, quadrupole, end and central plasmon are observed.

  19. Full-length apolipoprotein E protects against the neurotoxicity of an apoE-related peptide

    PubMed Central

    Crutcher, K.A.; Lilley, H.N.; Anthony, S. R.; Zhou, W.; Narayanaswami, V.

    2009-01-01

    Apolipoprotein E was found to protect against the neurotoxic effects of a dimeric peptide derived from the receptor-binding region of this protein (residues 141–149). Both apoE3 and apoE4 conferred protection but the major N-terminal fragment of each isoform did not. Nor was significant protection provided by bovine serum albumin or apoA-I. Full-length apoE3 and apoE4 also inhibited the uptake of a fluorescent-labeled derivative of the peptide, suggesting that the mechanism of inhibition might involve competition for cell surface receptors/proteoglycans that mediate endocytosis and/or signaling pathways. These results might bear on the question of the role of apoE in neuronal degeneration, such as occurs in Alzheimer’s disease where apoE4 confers a significantly greater risk of pathology. PMID:19836363

  20. Absence of apolipoprotein E protects mice from cerebral malaria.

    PubMed

    Kassa, Fikregabrail Aberra; Van Den Ham, Kristin; Rainone, Anthony; Fournier, Sylvie; Boilard, Eric; Olivier, Martin

    2016-09-20

    Cerebral malaria claims the life of millions of people each year, particularly those of children, and is a major global public health problem. Thus, the identification of novel malaria biomarkers that could be utilized as diagnostic or therapeutic targets is becoming increasingly important. Using a proteomic approach, we previously identified unique biomarkers in the sera of malaria-infected individuals, including apolipoprotein E (ApoE). ApoE is the dominant apolipoprotein in the brain and has been implicated in several neurological disorders; therefore, we were interested in the potential role of ApoE in cerebral malaria. Here we report the first demonstration that cerebral malaria is markedly attenuated in ApoE(-/-) mice. The protection provided by the absence of ApoE was associated with decreased sequestration of parasites and T cells within the brain, and was determined to be independent from the involvement of ApoE receptors and from the altered lipid metabolism associated with the knock-out mice. Importantly, we demonstrated that treatment of mice with the ApoE antagonist heparin octasaccharide significantly decreased the incidence of cerebral malaria. Overall, our study indicates that the reduction of ApoE could be utilized in the development of therapeutic treatments aimed at mitigating the neuropathology of cerebral malaria.

  1. Absence of apolipoprotein E protects mice from cerebral malaria

    PubMed Central

    Kassa, Fikregabrail Aberra; Van Den Ham, Kristin; Rainone, Anthony; Fournier, Sylvie; Boilard, Eric; Olivier, Martin

    2016-01-01

    Cerebral malaria claims the life of millions of people each year, particularly those of children, and is a major global public health problem. Thus, the identification of novel malaria biomarkers that could be utilized as diagnostic or therapeutic targets is becoming increasingly important. Using a proteomic approach, we previously identified unique biomarkers in the sera of malaria-infected individuals, including apolipoprotein E (ApoE). ApoE is the dominant apolipoprotein in the brain and has been implicated in several neurological disorders; therefore, we were interested in the potential role of ApoE in cerebral malaria. Here we report the first demonstration that cerebral malaria is markedly attenuated in ApoE−/− mice. The protection provided by the absence of ApoE was associated with decreased sequestration of parasites and T cells within the brain, and was determined to be independent from the involvement of ApoE receptors and from the altered lipid metabolism associated with the knock-out mice. Importantly, we demonstrated that treatment of mice with the ApoE antagonist heparin octasaccharide significantly decreased the incidence of cerebral malaria. Overall, our study indicates that the reduction of ApoE could be utilized in the development of therapeutic treatments aimed at mitigating the neuropathology of cerebral malaria. PMID:27647324

  2. Apolipoprotein E and Alzheimer disease: risk, mechanisms, and therapy

    PubMed Central

    Liu, Chia-Chen; Kanekiyo, Takahisa; Xu, Huaxi; Bu, Guojun

    2013-01-01

    Apolipoprotein E (ApoE) is a major cholesterol carrier that supports lipid transport and injury repair in the brain. APOE polymorphic alleles are the main genetic determinants of Alzheimer disease (AD) risk: individuals carrying the ε4 allele are at increased risk of AD compared with those carrying the more common ε3 allele, whereas the ε2 allele decreases risk. Presence of the APOE ε4 allele is also associated with increased risk for cerebral amyloid angiopathy and age-related cognitive decline during normal ageing. ApoE–lipoproteins bind to several cell-surface receptors to deliver lipids and also to hydrophobic amyloid-β (Aβ) peptide, which is thought to initiate toxic events that lead to synaptic dysfunction and neurodegeneration in AD. ApoE isoforms differentially regulate Aβ aggregation and clearance in the brain, and have distinct functions in regulating brain lipid transport, glucose metabolism, neuronal signalling, neuroinflammation, and mitochondrial function. In this Review, we describe current knowledge on ApoE in the CNS, with a particular emphasis on the clinical and pathological features associated with carriers of different ApoE isoforms. We also discuss Aβ-dependent and Aβ-independent mechanisms that link ApoE4 status with AD risk, and consider how to design effective strategies for AD therapy by targeting ApoE. PMID:23296339

  3. Cerebrovascular effects of apolipoprotein E: implications for Alzheimer disease.

    PubMed

    Zlokovic, Berislav V

    2013-04-01

    Human apolipoprotein E (apoE) has 3 isoforms: apoE2, apoE3, and apoE4. APOE4 is a major genetic risk factor for Alzheimer disease and is associated with dementia in Down syndrome and poor neurological outcome after traumatic brain injury, cerebral hemorrhage, and other neuropathological disorders. While apoE4 can induce neuropathology by participating in various cellular and molecular pathways, herein I review data supporting the hypothesis that apoE4 has direct toxic effects on the cerebrovascular system that in turn can lead to secondary neuronal dysfunction and degeneration as well as accumulation of neurotoxins in brain such as β-amyloid (Aβ) in Alzheimer disease. I review Aβ-independent cerebrovascular effects of apoE, particularly activation of a proinflammatory cyclophilin A-mediated pathway in brain vascular pericytes by apoE4 that has recently been shown to lead to a loss of cerebrovascular integrity and blood-brain barrier breakdown causing neuronal injury. I also review Aβ-dependent cerebrovascular effects of apoE such as faulty Aβ clearance from brain to circulation by apoE4. Finally, I discuss isoform-specific interactions of apoE with low-density lipoprotein receptor-related protein 1 on brain vascular cells (ie, endothelial cells, pericytes), which play an important role in Aβ-independent and Aβ-dependent effects of apoE on cerebral vasculature.

  4. Apolipoprotein E and Alzheimer disease: risk, mechanisms and therapy.

    PubMed

    Liu, Chia-Chen; Liu, Chia-Chan; Kanekiyo, Takahisa; Xu, Huaxi; Bu, Guojun

    2013-02-01

    Apolipoprotein E (Apo-E) is a major cholesterol carrier that supports lipid transport and injury repair in the brain. APOE polymorphic alleles are the main genetic determinants of Alzheimer disease (AD) risk: individuals carrying the ε4 allele are at increased risk of AD compared with those carrying the more common ε3 allele, whereas the ε2 allele decreases risk. Presence of the APOE ε4 allele is also associated with increased risk of cerebral amyloid angiopathy and age-related cognitive decline during normal ageing. Apo-E-lipoproteins bind to several cell-surface receptors to deliver lipids, and also to hydrophobic amyloid-β (Aβ) peptide, which is thought to initiate toxic events that lead to synaptic dysfunction and neurodegeneration in AD. Apo-E isoforms differentially regulate Aβ aggregation and clearance in the brain, and have distinct functions in regulating brain lipid transport, glucose metabolism, neuronal signalling, neuroinflammation, and mitochondrial function. In this Review, we describe current knowledge on Apo-E in the CNS, with a particular emphasis on the clinical and pathological features associated with carriers of different Apo-E isoforms. We also discuss Aβ-dependent and Aβ-independent mechanisms that link Apo-E4 status with AD risk, and consider how to design effective strategies for AD therapy by targeting Apo-E.

  5. Prenatal mercury exposure, neurodevelopment and apolipoprotein E genetic polymorphism.

    PubMed

    Snoj Tratnik, Janja; Falnoga, Ingrid; Trdin, Ajda; Mazej, Darja; Fajon, Vesna; Miklavčič, Ana; Kobal, Alfred B; Osredkar, Joško; Sešek Briški, Alenka; Krsnik, Mladen; Neubauer, David; Kodrič, Jana; Stropnik, Staša; Gosar, David; Lešnik Musek, Petra; Marc, Janja; Jurkovič Mlakar, Simona; Petrović, Oleg; Vlašić-Cicvarić, Inge; Prpić, Igor; Milardović, Ana; Radić Nišević, Jelena; Vuković, Danijela; Fišić, Elizabeta; Špirić, Zdravko; Horvat, Milena

    2017-01-01

    The aim of the present study was to evaluate the association between prenatal exposure to mercury (Hg) and neurodevelopment of the child, taking into account genetic polymorphism of apolipoprotein E (Apoe) and other relevant confounders. Six hundred and one mother-child pairs were recruited from the central Slovenia region and 243 from Rijeka, on the Croatian coast of the northern Adriatic. The total Hg in cord blood, Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) assessment at 18 months of age and Apoe genotyping was performed on 361 children; 237 of them were from Slovenia and 124 from Croatia. The results showed negative association between low-to-moderate Hg exposure in children with normal neurodevelopmental outcome and cognitive and fine motor scores at 18 months of age as assessed by Bayley III. The Hg-related decrease in cognitive score was observed only in children carrying at least one Apoe ε4 allele, while the decrease in fine motor scores was independent of the Apoe genotype. Adjusting for selenium (Se) and lead (Pb) levels, a positive association between Se and the language score and a negative association between Pb and the motor score was observed, but not in the subgroup of children carrying the ε4 allele.

  6. Alzheimer's disease, apolipoprotein E and hormone replacement therapy.

    PubMed

    Depypere, H; Vierin, A; Weyers, S; Sieben, A

    2016-12-01

    Alzheimer's disease is the most frequent cause of dementia in older patients. The prevalence is higher in women than in men. This may be the result of both the higher life expectancy of women and the loss of neuroprotective estrogen after menopause. Earlier age at menopause (spontaneous or surgical) is associated with an enhanced risk of developing Alzheimer's disease. Therefore, it is postulated that estrogen could be protective against it. If so, increasing exposure to estrogen through the use of postmenopausal hormone replacement could also be protective against Alzheimer's disease. The results of the clinical studies that have examined this hypothesis are inconclusive, however. One explanation for this is that estrogen treatment is protective only if it is initiated in the years immediately after menopause. Another possibility is that the neuroprotective effects of estrogen are negated by a particular genotype of apolipoprotein E. This protein plays an important role in cholesterol transport to the neurons. Studies that have examined the link between estrogen replacement therapy, Alzheimer's disease and the E4 allele of ApoE are inconclusive. This article reviews the literature on the influence of hormone replacement therapy on the incidence and progression of Alzheimer's disease.

  7. Apolipoprotein E receptor 2 is involved in the thrombotic complications in a murine model of the antiphospholipid syndrome.

    PubMed

    Romay-Penabad, Zurina; Aguilar-Valenzuela, Renan; Urbanus, Rolf T; Derksen, Ronald H W M; Pennings, Maarten T T; Papalardo, Elizabeth; Shilagard, Tuya; Vargas, Gracie; Hwang, Yong; de Groot, Philip G; Pierangeli, Silvia S

    2011-01-27

    Antiphospholipid (aPL)/anti-β(2) glycoprotein I (anti-β(2)GPI) antibodies stimulates tissue factor (TF) expression within vasculature and in blood cells, thereby leading to increased thrombosis. Several cellular receptors have been proposed to mediate these effects, but no convincing evidence for the involvement of a specific one has been provided. We investigated the role of Apolipoprotein E receptor 2 (ApoER2') on the pathogenic effects of a patient-derived polyclonal aPL IgG preparation (IgG-APS), a murine anti-β(2)GPI monoclonal antibody (E7) and of a constructed dimeric β(2)GPI I (dimer), which in vitro mimics β(2)GPI-antibody immune complexes, using an animal model of thrombosis, and ApoER2-deficient (-/-) mice. In wild type mice, IgG-APS, E7 and the dimer increased thrombus formation, carotid artery TF activity as well as peritoneal macrophage TF activity/expression. Those pathogenic effects were significantly reduced in ApoER2 (-/-) mice. In addition, those effects induced by the IgG-APS, by E7 and by the dimer were inhibited by treatment of wild-type mice with soluble binding domain 1 of ApoER2 (sBD1). Altogether these data show that ApoER2 is involved in pathogenesis of antiphospholipids antibodies.

  8. Apolipoprotein E receptor 2 is involved in the thrombotic complications in a murine model of the antiphospholipid syndrome

    PubMed Central

    Romay-Penabad, Zurina; Aguilar-Valenzuela, Renan; Urbanus, Rolf T.; Derksen, Ronald H. W. M.; Pennings, Maarten T. T.; Papalardo, Elizabeth; Shilagard, Tuya; Vargas, Gracie; Hwang, Yong; de Groot, Philip G.

    2011-01-01

    Antiphospholipid (aPL)/anti-β2 glycoprotein I (anti-β2GPI) antibodies stimulates tissue factor (TF) expression within vasculature and in blood cells, thereby leading to increased thrombosis. Several cellular receptors have been proposed to mediate these effects, but no convincing evidence for the involvement of a specific one has been provided. We investigated the role of Apolipoprotein E receptor 2 (ApoER2′) on the pathogenic effects of a patient-derived polyclonal aPL IgG preparation (IgG-APS), a murine anti-β2GPI monoclonal antibody (E7) and of a constructed dimeric β2GPI I (dimer), which in vitro mimics β2GPI-antibody immune complexes, using an animal model of thrombosis, and ApoER2-deficient (−/−) mice. In wild type mice, IgG-APS, E7 and the dimer increased thrombus formation, carotid artery TF activity as well as peritoneal macrophage TF activity/expression. Those pathogenic effects were significantly reduced in ApoER2 (−/−) mice. In addition, those effects induced by the IgG-APS, by E7 and by the dimer were inhibited by treatment of wild-type mice with soluble binding domain 1 of ApoER2 (sBD1). Altogether these data show that ApoER2 is involved in pathogenesis of antiphospholipids antibodies. PMID:21119114

  9. Subunit interface mutants of rabbit muscle aldolase form active dimers.

    PubMed Central

    Beernink, P. T.; Tolan, D. R.

    1994-01-01

    We report the construction of subunit interface mutants of rabbit muscle aldolase A with altered quaternary structure. A mutation has been described that causes nonspherocytic hemolytic anemia and produces a thermolabile aldolase (Kishi H et al., 1987, Proc Natl Acad Sci USA 84:8623-8627). The disease arises from substitution of Gly for Asp-128, a residue at the subunit interface of human aldolase A. To elucidate the role of this residue in the highly homologous rabbit aldolase A, site-directed mutagenesis is used to replace Asp-128 with Gly, Ala, Asn, Gln, or Val. Rabbit aldolase D128G purified from Escherichia coli is found to be similar to human D128G by kinetic analysis, CD, and thermal inactivation assays. All of the mutant rabbit aldolases are similar to the wild-type rabbit enzyme in secondary structure and kinetic properties. In contrast, whereas the wild-type enzyme is a tetramer, chemical crosslinking and gel filtration indicate that a new dimeric species exists for the mutants. In sedimentation velocity experiments, the mutant enzymes as mixtures of dimer and tetramer at 4 degrees C. Sedimentation at 20 degrees C shows that the mutant enzymes are > 99.5% dimeric and, in the presence of substrate, that the dimeric species is active. Differential scanning calorimetry demonstrates that Tm values of the mutant enzymes are decreased by 12 degrees C compared to wild-type enzyme. The results indicate that Asp-128 is important for interface stability and suggest that 1 role of the quaternary structure of aldolase is to provide thermostability. PMID:7833800

  10. Helical arrays of U-shaped ATP synthase dimers form tubular cristae in ciliate mitochondria

    PubMed Central

    Mühleip, Alexander W.; Joos, Friederike; Wigge, Christoph; Frangakis, Achilleas S.; Kühlbrandt, Werner; Davies, Karen M.

    2016-01-01

    F1Fo-ATP synthases are universal energy-converting membrane protein complexes that synthesize ATP from ADP and inorganic phosphate. In mitochondria of yeast and mammals, the ATP synthase forms V-shaped dimers, which assemble into rows along the highly curved ridges of lamellar cristae. Using electron cryotomography and subtomogram averaging, we have determined the in situ structure and organization of the mitochondrial ATP synthase dimer of the ciliate Paramecium tetraurelia. The ATP synthase forms U-shaped dimers with parallel monomers. Each complex has a prominent intracrista domain, which links the c-ring of one monomer to the peripheral stalk of the other. Close interaction of intracrista domains in adjacent dimers results in the formation of helical ATP synthase dimer arrays, which differ from the loose dimer rows in all other organisms observed so far. The parameters of the helical arrays match those of the cristae tubes, suggesting the unique features of the P. tetraurelia ATP synthase are directly responsible for generating the helical tubular cristae. We conclude that despite major structural differences between ATP synthase dimers of ciliates and other eukaryotes, the formation of ATP synthase dimer rows is a universal feature of mitochondria and a fundamental determinant of cristae morphology. PMID:27402755

  11. Apolipoprotein E promotes lipid accumulation and differentiation in human adipocytes

    SciTech Connect

    Lasrich, Dorothee; Bartelt, Alexander; Grewal, Thomas; Heeren, Joerg

    2015-09-10

    Several studies in mice indicate a role for apolipoprotein E (APOE) in lipid accumulation and adipogenic differentiation in adipose tissue. However, little is yet known if APOE functions in a similar manner in human adipocytes. This prompted us to compare lipid loading and expression of adipocyte differentiation markers in APOE-deficient and control adipocytes using the differentiated human mesenchymal stem cell line hMSC-Tert as well as primary human and mouse adipocytes as model systems. Differentiated hMSC-Tert were stably transduced with or without siRNA targeting APOE while murine adipocytes were isolated from wild type and Apoe knockout mice. Human APOE knockdown hMSC-Tert adipocytes accumulated markedly less triglycerides compared to control cells. This correlated with strongly decreased gene expression levels of adipocyte markers such as adiponectin (ADIPOQ) and fatty acid binding protein 4 (FABP4) as well as the key transcription factor driving adipocyte differentiation, peroxisome proliferator activator receptor gamma (PPARG), in particular the PPARG2 isoform. Similarly, differentiation of murine Apoe-deficient adipocytes was characterized by reduced gene expression of Adipoq, Fabp4 and Pparg. Interestingly, incubation of APOE-deficient hMSC-Tert adipocytes with conditioned media from APOE3-overexpressing adipocytes or APOE-containing Very Low Density Lipoprotein (VLDL) partially restored triglyceride accumulation, but were unable to induce adipocyte differentiation, as judged by expression of adipocyte markers. Taken together, depletion of endogenous APOE in human adipocytes severely impairs lipid accumulation, which is associated with an inability to initiate differentiation. - Highlights: • Immortalized human mesenchymal stem cells were used to study adipocyte development. • Knockdown of endogenous APOE lead to impaired lipid accumulation and adipogenesis. • APOE supplementation partially restored lipid accumulation but not differentiation.

  12. Thyroid hormones upregulate apolipoprotein E gene expression in astrocytes.

    PubMed

    Roman, Corina; Fuior, Elena V; Trusca, Violeta G; Kardassis, Dimitris; Simionescu, Maya; Gafencu, Anca V

    Apolipoprotein E (apoE), a protein mainly involved in lipid metabolism, is associated with several neurodegenerative disorders including Alzheimer's disease. Despite numerous attempts to elucidate apoE gene regulation in the brain, the exact mechanism is still uncovered. The mechanism of apoE gene regulation in the brain involves the proximal promoter and multienhancers ME.1 and ME.2, which evolved by gene duplication. Herein we questioned whether thyroid hormones and their nuclear receptors have a role in apoE gene regulation in astrocytes. Our data showed that thyroid hormones increase apoE gene expression in HTB14 astrocytes in a dose-dependent manner. This effect can be intermediated by the thyroid receptor β (TRβ) which is expressed in these cells. In the presence of triiodothyronine (T3) and 9-cis retinoic acid, in astrocytes transfected to overexpress TRβ and retinoid X receptor α (RXRα), apoE promoter was indirectly activated through the interaction with ME.2. To determine the location of TRβ/RXRα binding site on ME.2, we performed DNA pull down assays and found that TRβ/RXRα complex bound to the region 341-488 of ME.2. This result was confirmed by transient transfection experiments in which a series of 5'- and 3'-deletion mutants of ME.2 were used. These data support the existence of a biologically active TRβ binding site starting at 409 in ME.2. In conclusion, our data revealed that ligand-activated TRβ/RXRα heterodimers bind with high efficiency on tissue-specific distal regulatory element ME.2 and thus modulate apoE gene expression in the brain.

  13. Isoliquiritigenin Attenuates Atherogenesis in Apolipoprotein E-Deficient Mice

    PubMed Central

    Du, Fen; Gesang, Quzhen; Cao, Jia; Qian, Mei; Ma, Li; Wu, Dongfang; Yu, Hong

    2016-01-01

    Isoliquiritigenin (ISL) exhibits antioxidation and anti-inflammation activity. We sought to investigate the effects and mechanism of ISL on the development of atherosclerotic lesions in apolipoprotein E-deficient (apoE−/−) mice. Firstly, we determined that ISL reduced the mRNA levels of inflammatory factors interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and monocyte chemotactic protein-1 (MCP-1), while it increased the expression of several lipoprotein-related genes in peritoneal macrophages treated with lipopolysaccharide (LPS). ISL also enhanced peroxisome proliferator-activated receptor gamma (PPARγ) protein levels and reversed the changes of ATP-binding cassette transporter A (ABCA1) and cluster of differentiation 36 (CD36) in macrophages treated with oxidative low-density lipoprotein (ox-LDL). Then, in an in vivo study, female apoE−/− mice were fed a Western diet with ISL (0, 20, 100 mg/kg/day) added for 12 weeks. We found that ISL decreased the plasma cholesterol levels of very low-density lipoprotein (VLDL)/LDL, promoted plasma superoxide dismutase (SOD) and paraoxonase-1 (PON1) activities, and decreased plasma IL-6, TNF-α, and MCP-1 levels. Moreover, ISL significantly reduced the atherosclerotic lesions and hepatic steatosis in apoE−/− mice. In the liver, ISL altered the expression of several key genes (such as SRBI, ABCA1, ABCG8, PPARγ, and FASN) involving cholesterol-selective uptake and excretion into bile, triglyceride (TG) biosynthesis, and inflammation. These results suggest that the atheroprotective effects of ISL are due to the improvement of lipid metabolism, antioxidation, and anti-inflammation, which involve PPARγ-dependent signaling. PMID:27869741

  14. Does Apolipoprotein E Genotype Increase Risk of Postoperative Delirium?

    PubMed Central

    Vasunilashorn, Sarinnapha; Ngo, Long; Kosar, Cyrus M.; Fong, Tamara G.; Jones, Richard N.

    2015-01-01

    Objectives To determine whether Apolipoprotein E (ApoE) is associated with postoperative delirium incidence, severity, and duration in older patients free of dementia at baseline. Design, Setting, Participants We examined 557 non-demented patients age ≥70 undergoing major non-cardiac surgery enrolled in the Successful Aging after Elective Surgery (SAGES) Study. Measurements We considered three ApoE measures: ε2, ε4 carriers vs. non-carriers, and a three-category ApoE measure. Delirium was determined using the Confusion Assessment Method (CAM) and chart review. We used generalized linear models to estimate the association between ApoE and delirium incidence, severity (peak CAM Severity [CAM-S] score), and days. Results ApoE ε2 and ε4 was present in 15% and 19% respectively, and postoperative delirium occurred in 24%. Among patients with delirium, the mean peak CAM-S score was 8.0 (standard deviation 4), with most patients experiencing one or two delirium days (51% or 28%, respectively). After adjusting for age, sex, surgical procedure, and preoperative cognitive function, ApoE ε4 and ε2 carrier status were not associated with postoperative delirium: RR for ε4=1.0, 95% confidence interval (CI) 0.7-1.5 and RR for ε2=0.9, 95% CI 0.6-1.4. No association between ApoE and delirium severity or number of delirium days was observed. Conclusions In older surgery patients free of dementia, our findings do not support the hypothesis that the ApoE genotype does not confer either risk or protection in postoperative delirium incidence, severity, or duration. Thus, an important genetic risk factor for Alzheimer's Disease does not affect risk of delirium. PMID:26238230

  15. Heterogeneous expression of apolipoprotein-E by human macrophages

    PubMed Central

    Tedla, Nicodemus; Glaros, Elias N; Brunk, Ulf T; Jessup, Wendy; Garner, Brett

    2004-01-01

    Apolipoprotein-E (apoE) is expressed at high levels by macrophages. In addition to its role in lipid transport, macrophage-derived apoE plays an important role in immunoregulation. Previous studies have identified macrophage subpopulations that differ substantially in their ability to synthesize specific cytokines and enzymes, however, potential heterogeneous macrophage apoE expression has not been studied. Here we examined apoE expression in human THP-1 macrophages and monocyte-derived macrophages (MDM). Using immunocytochemistry and flow cytometry methods we reveal a striking heterogeneity in macrophage apoE expression in both cell types. In phorbol-ester-differentiated THP-1 macrophages, 5% of the cells over-expressed apoE at levels more than 50-fold higher than the rest of the population. ApoE over-expressing THP-1 macrophages contained condensed/fragmented nuclei and increased levels of activated caspase-3 indicating induction of apoptosis. In MDM, 3–5% of the cells also highly over-expressed apoE, up to 50-fold higher than the rest of the population; however, this was not associated with obvious nuclear alterations. The apoE over-expressing MDM were larger, more granular, and more autofluorescent than the majority of cells and they contained numerous vesicle-like structures that appeared to be coated by apoE. Flow cytometry experiments indicated that the apoE over-expressing subpopulation of MDM were positive for CD14, CD11b/Mac-1 and CD68. These observations suggest that specific macrophage subpopulations may be important for apoE-mediated immunoregulation and clearly indicate that subpopulation heterogeneity should be taken into account when investigating macrophage apoE expression. PMID:15500620

  16. Cerebral lipid deposition in aged apolipoprotein-E-deficient mice.

    PubMed Central

    Walker, L. C.; Parker, C. A.; Lipinski, W. J.; Callahan, M. J.; Carroll, R. T.; Gandy, S. E.; Smith, J. D.; Jucker, M.; Bisgaier, C. L.

    1997-01-01

    To assess the influence of age and diet on cerebral pathology in mice lacking apolipoprotein E (apoE), four male apoE knockout mice (epsilon -/-), and five male wild-type (epsilon +/+) littermate controls were placed on a high-fat/high-cholesterol diet for 7 weeks beginning at 17 months of age. All four aged knockout mice developed xanthomatous lesions in the brain consisting mostly of crystalline cholesterol clefts, lipid globules, and foam cells. Smaller xanthomas were confined mainly to the choroid plexus and ventral fornix in the roof of the third ventricle, occasionally extending subpially along the choroidal fissure and into the adjacent parenchyma. More advanced xanthomas disrupted adjoining neural tissue in the fornix, hippocampus, and dorsal diencephalon; in one case, over 60% of one telencephalic hemisphere, including nearly the entire neocortex, was obliterated by the lesion. No xanthomas were observed in aged wild-type controls fed the high-fat/high-cholesterol diet. Brains from 42 additional animals, fed only conventional chow, were examined; 3 of 15 aged (15- to 23-month-old) apoE knockout mice developed small choroidal xanthomas. In contrast, no lesions were observed in five young (2- to 4-month-old) apoE knockout mice or in any wild-type controls between the ages of 2 and 23 months. Our findings indicate that disorders of lipid metabolism can induce significant pathological changes in the central nervous system of aged apoE knockout mice, particularly those on a high-fat/high-cholesterol diet. It may be fruitful to seek potential interactions between genetic factors and diet in modulating the risk of Alzheimer's disease and other neurodegenerative disorders in aged humans. Images Figure 1 Figure 2 PMID:9358763

  17. Human apolipoprotein E expression in Escherichia coli: structural and functional identity of the bacterially produced protein with plasma apolipoprotein E.

    PubMed Central

    Vogel, T; Weisgraber, K H; Zeevi, M I; Ben-Artzi, H; Levanon, A Z; Rall, S C; Innerarity, T L; Hui, D Y; Taylor, J M; Kanner, D

    1985-01-01

    Human apolipoprotein E (apoE) was produced in Escherichia coli by transforming cells with an expression vector containing a reconstructed apoE cDNA, a lambda PL promoter regulated by the thermolabile cI repressor, and a ribosomal binding site derived from the lambda cII or the E. coli beta-lactamase gene. Transformed cells induced at 42 degrees C for short periods of time (less than 20 min) produced apoE, which accumulated in the cells at levels of approximately equal to 1% of the total soluble cellular protein. Longer induction periods resulted in cell lysis and the proteolytic destruction of apoE. The bacterially produced apoE was purified by heparin-Sepharose affinity chromatography, Sephacryl S-300 gel filtration, and preparative Immobiline isoelectric focusing. The final yield was approximately equal to 20% of the initial apoE present in the cells. Except for an additional methionine at the amino terminus, the bacterially produced apoE was indistinguishable from authentic human plasma apoE as determined by NaDodSO4 and isoelectric focusing gel electrophoresis, amino acid composition of the total protein as well as its cyanogen bromide fragments, and partial amino acid sequence analysis (residues 1-17 and 109-164). Both the bacterially produced and authentic plasma apoE bound similarly to apolipoprotein B,E(low density lipoprotein) receptors of human fibroblasts and to hepatic apoE receptors. Intravenous injection resulted in similar rates of clearance for both the bacterially produced and authentic apoE from rabbit and rat plasma (approximately equal to 50% removed in 20 min). The ability to synthesize a bacterially produced human apolipoprotein with biological properties indistinguishable from those of the native protein will allow the production of large quantities of apoE for use in further investigations of the biological and physiological properties of this apolipoprotein. Images PMID:3909150

  18. Specific Regional Transcription of Apolipoprotein E in Human Brain Neurons

    PubMed Central

    Xu, Pu-Ting; Gilbert, John R.; Qiu, Hui-Ling; Ervin, John; Rothrock-Christian, Tracie R.; Hulette, Christine; Schmechel, Donald E.

    1999-01-01

    In central nervous system injury and disease, apolipoprotein E (APOE, gene; apoE, protein) might be involved in neuronal injury and death indirectly through extracellular effects and/or more directly through intracellular effects on neuronal metabolism. Although intracellular effects could clearly be mediated by neuronal uptake of extracellular apoE, recent experiments in injury models in normal rodents and in mice transgenic for the human APOE gene suggest the additional possibility of intraneuronal synthesis. To examine whether APOE might be synthesized by human neurons, we performed in situ hybridization on paraffin-embedded and frozen brain sections from three nondemented controls and five Alzheimer’s disease (AD) patients using digoxigenin-labeled antisense and sense cRNA probes to human APOE. Using the antisense APOE probes, we found the expected strong hybridization signal in glial cells as well as a generally fainter signal in selected neurons in cerebral cortex and hippocampus. In hippocampus, many APOE mRNA-containing neurons were observed in sectors CA1 to CA4 and the granule cell layer of the dentate gyrus. In these regions, APOE mRNA containing neurons could be observed adjacent to nonhybridizing neurons of the same cell class. APOE mRNA transcription in neurons is regionally specific. In cerebellar cortex, APOE mRNA was seen only in Bergmann glial cells and scattered astrocytes but not in Purkinje cells or granule cell neurons. ApoE immunocytochemical localization in semi-adjacent sections supported the selectivity of APOE transcription. These results demonstrate the expected result that APOE mRNA is transcribed and expressed in glial cells in human brain. The important new finding is that APOE mRNA is also transcribed and expressed in many neurons in frontal cortex and human hippocampus but not in neurons of cerebellar cortex from the same brains. This regionally specific human APOE gene expression suggests that synthesis of apoE might play a role

  19. Inter-molecular crosslinking activity is engendered by the dimeric form of transglutaminase 2.

    PubMed

    Kim, Nayeon; Lee, Won-Kyu; Lee, Seon-Hyeong; Jin, Kyeong Sik; Kim, Kyung-Hee; Lee, Younho; Song, Minsoo; Kim, Soo-Youl

    2017-03-01

    Transglutaminase 2 (TGase 2) catalyzes a crosslink between protein bound-glutamine and -lysine. We proposed the mechanism of TGase 2 activation depends on conformation change from unfolded monomer to unfolded dimer. We found that TGase 2 has temperature-sensitive conformation change system at 30 °C. Small-angle X-ray scattering analysis showed that the enzyme was maintained as an unfolded monomer at temperatures below 30 °C, but changed to an unfolded dimer at over 30 °C. Mass analysis revealed that the C-terminus of TGase 2 was the critical region for dimerization. Furthermore, this conformational switch creates new biochemical reactivity that catalyzed inter-molecular crosslink at above 30 °C as an unfolded dimer of TGase 2 while catalyzed intra-molecular crosslink at below 30 °C as an unfolded monomer of TGase 2. The mechanism of TGase 2 activation depends on temperature-sensitive conformation change from unfolded monomer to unfolded dimer at over 30 °C. Furthermore, inter-molecular crosslinking activity is generated by the dimeric form of TGase 2. TGase 2 switches its conformation from a monomer to a dimer following a change in temperature, which engendered unique catalytic function of enzyme as inter-molecular crosslinking activity with calcium.

  20. Nicotinamidase/pyrazinamidase of Mycobacterium tuberculosis forms homo-dimers stabilized by disulfide bonds

    PubMed Central

    Rueda, Daniel; Sheen, Patricia; Gilman, Robert H.; Bueno, Carlos; Santos, Marco; Pando-Robles, Victoria; Batista, Cesar V.; Zimic, Mirko

    2014-01-01

    Recombinant wild-pyrazinamidase from H37Rv M. tuberculosis was analyzed by gel electrophoresis under differential reducing conditions to evaluate its quaternary structure. PZAse was fractionated by size exclusion chromatography under non-reducing conditions. PZAse activity was measured and mass spectrometry analysis was performed to determine the identity of proteins by de novo sequencing and to determine the presence of disulfide bonds. This study confirmed that M. tuberculosis wild type PZAse was able to form homo-dimers in vitro. Homo-dimers showed a slightly lower specific PZAse activity compared to monomeric PZAse. PZAse dimers were dissociated into monomers in response to reducing conditions. Mass spectrometry analysis confirmed the existence of disulfide bonds (C72-C138 and C138-C138) stabilizing the quaternary structure of the PZAse homo-dimer. PMID:25199451

  1. Comparative surface antimicrobial properties of synthetic biocides and novel human apolipoprotein E derived antimicrobial peptides.

    PubMed

    Forbes, Sarah; McBain, Andrew J; Felton-Smith, Susan; Jowitt, Thomas A; Birchenough, Holly L; Dobson, Curtis B

    2013-07-01

    Medical device infection remains a major clinical concern. Biocidal compounds have been incorporated into medical device materials ideally to inhibit bacterial colonisation whilst exhibiting relatively low cytotoxicity. We compared the antibacterial activity, anti-biofilm efficacy and cytotoxicity of a novel peptide derivative of human apolipoprotein E (apoEdpL-W) to that of commonly used biocides, before and after coating onto a range of standard polymers. Since the antimicrobial function of most biocides frequently involves associations with cellular membranes, we have also studied the detailed interactions of the test antimicrobials with phospholipid bilayers, using the quartz crystal microbalance device combined with dual-polarisation interferometry. ApoEdpL-W displayed broad-spectrum antibacterial activity and marked efficacy against nascent Staphylococcus aureus biofilms. Compounds showed better antimicrobial activity when combined with hydrogel materials than with non-porous materials. The membrane interactions of apoEdpL-W were most similar to that of PHMB, with both agents appearing to readily bind and insert into lipid bilayers, possibly forming pores. However apoEdpL-W showed lower cytotoxicity than PHMB, its efficacy was less affected by the presence of serum, and it demonstrated the highest level of biocompatibility of all the biocides, as indicated by our measurement of its antimicrobial biocompatibility index. This work shows the potential of apoEdpL-W as an effective antiseptic coating agent.

  2. Insulin resistance, dyslipidemia, and apolipoprotein E interactions as mechanisms in cognitive impairment and Alzheimer's disease

    PubMed Central

    Salameh, Therese S; Rhea, Elizabeth M; Hanson, Angela J

    2016-01-01

    An increased risk for Alzheimer's disease is associated with dyslipidemia and insulin resistance. A separate literature shows the genetic risk for developing Alzheimer's disease is strongly correlated to the presence of the E4 isoform of the apolipoprotein E carrier protein. Understanding how apolipoprotein E carrier protein, lipids, amyloid β peptides, glucose, central nervous system insulin, and peripheral insulin interact with one another in Alzheimer's disease is an area of increasing interest. Here, we will review the evidence relating apolipoprotein E carrier protein, lipids, and insulin action to Alzheimer's disease and Aβ peptides and then propose mechanisms as to how these factors might interact with one another to impair cognition and promote Alzheimer's disease. PMID:27470930

  3. Selective and asymmetric action of trypsin on the dimeric forms of seminal RNase.

    PubMed Central

    De Lorenzo, C.; Dal Piaz, F.; Piccoli, R.; Di Maro, A.; Pucci, P.; D'Alessio, G.

    1998-01-01

    Dimeric seminal RNase (BS-RNase) is an equilibrium mixture of conformationally different quaternary structures, one characterized by the interchange between subunits of their N-terminal ends (the MXM form); the other with no interchange (the M=M form). Controlled tryptic digestion of each isolated quaternary form generates, as limit digest products, folded and enzymatically active molecules, very resistant to further tryptic degradation. Electrospray mass spectrometric analyses and N-terminal sequence determinations indicate that trypsin can discriminate between the conformationally different quaternary structures of seminal RNase, and exerts a differential and asymmetric action on the two dimeric forms, depending on the original quaternary conformation of each form. The two digestion products from the MXM and the M=M dimeric forms have different structures, which are reminiscent of the original quaternary conformation of the dimers: one with interchange, the other with no interchange, of the N-terminal ends. The surprising resistance of these tryptic products to further tryptic action is explained by the persistence in each digestion product of the original intersubunit interface. PMID:9865960

  4. Orphan nuclear receptor NGFI-B forms dimers with nonclassical interface

    PubMed Central

    Calgaro, Marcos R.; Neto, Mario de Oliveira; Figueira, Ana Carolina M.; Santos, Maria A.M.; Portugal, Rodrigo V.; Guzzi, Carolina A.; Saidemberg, Daniel M.; Bleicher, Lucas; Vernal, Javier; Fernandez, Pablo; Terenzi, Hernán; Palma, Mario Sergio; Polikarpov, Igor

    2007-01-01

    The orphan receptor nerve growth factor-induced B (NGFI-B) is a member of the nuclear receptor's subfamily 4A (Nr4a). NGFI-B was shown to be capable of binding both as a monomer to an extended half-site containing a single AAAGGTCA motif and also as a homodimer to a widely separated everted repeat, as opposed to a large number of nuclear receptors that recognize and bind specific DNA sequences predominantly as homo- and/or heterodimers. To unveil the structural organization of NGFI-B in solution, we determined the quaternary structure of the NGFI-B LBD by a combination of ab initio procedures from small-angle X-ray scattering (SAXS) data and hydrogen–deuterium exchange followed by mass spectrometry. Here we report that the protein forms dimers in solution with a radius of gyration of 2.9 nm and maximum dimension of 9.0 nm. We also show that the NGFI-B LBD dimer is V-shaped, with the opening angle significantly larger than that of classical dimer's exemplified by estrogen receptor (ER) or retinoid X receptor (RXR). Surprisingly, NGFI-B dimers formation does not occur via the classical nuclear receptor dimerization interface exemplified by ER and RXR, but instead, involves an extended surface area composed of the loop between helices 3 and 4 and C-terminal fraction of the helix 3. Remarkably, the NGFI-B dimer interface is similar to the dimerization interface earlier revealed for glucocorticoid nuclear receptor (GR), which might be relevant to the recognition of cognate DNA response elements by NGFI-B and to antagonism of NGFI-B–dependent transcription exercised by GR in cells. PMID:17600153

  5. Does Possession of Apolipoprotein E[superscript E]4 Benefit Cognitive Function in Healthy Young Adults?

    ERIC Educational Resources Information Center

    Bunce, David; Anstey, Kaarin J.; Burns, Richard; Christensen, Helen; Easteal, Simon

    2011-01-01

    There is considerable evidence that the apolipoprotein E (APOE)[superscript E]4 allele is associated with cognitive deficits in older persons, and is a risk factor for dementia. However, it has recently been suggested that possession of the [superscript E]4 allele may benefit cognition in early adulthood. We tested this possibility in 5445…

  6. Dihydroxyacetone phosphate, DHAP, in the crystalline state: monomeric and dimeric forms.

    PubMed

    Slepokura, Katarzyna; Lis, Tadeusz

    2010-02-26

    It was shown that dihydroxyacetone phosphate may exist in both monomeric DHAP (C(3)H(7)O(6)P) and dimeric DHAP-dimer (C(6)H(14)O(12)P(2)) form. Monomeric DHAP was obtained in the form of four crystalline salts: CaCl(DHAP) x 2.9H(2)O (7a), Ca(2)Cl(3)(DHAP) x 5H(2)O (7b), CaCl(DHAP) x 2H(2)O (7c), and CaBr(DHAP) x 5H(2)O (7d) by crystallization from aqueous solutions containing DHAP acid and CaCl(2) or CaBr(2), or by direct crystallization from a solution containing DHAP precursor and CaCl(2). At least one of the salts is stable and may be stored in the crystalline state at room temperature for several months. The dimeric form was obtained by slow saturation of free DHAP syrup with ammonia at -18 degrees C and isolated in the form of its hydrated diammonium salt (NH(4))(2)(DHAP-dimer) x 4H(2)O (8). The synthesis of the compounds, their crystallization, and crystal structures determined by X-ray crystallography are described. In all 7a-d monomeric DHAP exists in the monoanionic form in an extended (in-plane) cisoid conformation, with both hydroxyl and ester oxygen atoms being synperiplanar to the carbonyl O atom. The crucial structural feature is the coordination manner, in which the terminal phosphate oxygen atoms act as chelating as well as bridging atoms for the calcium cations. Additionally, the DHAP monoanions chelate another Ca(2+) by the alpha-hydroxycarbonyl moiety, in a manner observed previously in dihydroxyacetone (DHA) calcium chloride complexes. In dimeric 8 the anion is a trans isomer with the dioxane ring in a chair conformation with the hydroxyl groups in axial positions and the phosphomethyl group in an equatorial position.

  7. Beta-amyloid protein-containing inclusions in skeletal muscle of apolipoprotein-E-deficient mice.

    PubMed Central

    Robertson, T. A.; Dutton, N. S.; Martins, R. N.; Roses, A. D.; Kakulas, B. A.; Papadimitriou, J. M.

    1997-01-01

    The tibialis anterior muscle and soleus muscle of apolipoprotein-E-deficient mice were examined by light and electron microscopy. By light microscopy, sarcoplasmic inclusions were seen in tibialis anterior muscle and 40% of type 2 myofibers were affected in all animals over 8 months of age. These inclusions reacted for nonspecific esterase, cytochrome oxidase, and myoadenylate deaminase and were also periodic acid Schiff positive and stained basophilic with hematoxylin. Moreover, they reacted immunocytochemically with an antibody specific to fragment 17 to 24 of the published sequence of Alzheimer's cerebrovascular amyloid peptide. Immunoreactivity was lost when the antibody was adsorbed with the appropriate synthetic peptide. Ultrastructurally, the inclusions consisted of tubular arrays and were similar to those observed in human muscle in several pathological conditions. In type 1 myofibers of both tibialis anterior and soleus muscle, however, mitochondrial abnormalities including an increase in their number and size were detected, but tubular aggregates were not seen. These large mitochondria possessed an electron-dense inner chamber with an increased number of tightly packed cristae. The results obtained suggest that in these mice there is a disturbed lipid metabolism in skeletal muscle fibers that manifests itself with an accumulation of phospholipid in the form of sarcoplasmic reticulum tubules in the type 2 fibers and enlarged mitochondria with tightly packed cristae in the type 1 fibers. In addition, beta-amyloid protein was closely associated with the accumulated tubules and vesicles of sarcoplasmic reticulum and may represent dysregulation of amyloid precursor protein metabolism. Images Figure 1 Figure 2 Figure 3 PMID:9033257

  8. Active monomeric and dimeric forms of Pseudomonas putida glyoxalase I: evidence for 3D domain swapping.

    PubMed

    Saint-Jean, A P; Phillips, K R; Creighton, D J; Stone, M J

    1998-07-21

    3D domain swapping of proteins involves the interconversion of a monomer containing a single domain-domain interface and a 2-fold symmetrical dimer containing two equivalent intermolecular interfaces. Human glyoxalase I has the structure of a domain-swapped dimer [Cameron, A. D., Olin, B., Ridderström, M., Mannervik, B., and Jones, T. A. (1997) EMBO J. 16, 3386-3395] but Pseudomonas putida glyoxalase I has been reported to be monomeric [Rhee, H.-I., Murata, K., and Kimura, A. (1986) Biochem. Biophys. Res. Commun. 141, 993-999]. We show here that recombinant P. putida glyoxalase I is an active dimer (kcat approximately 500 +/- 100 s-1; KM approximately 0.4 +/- 0.2 mM) with two zinc ions per dimer. The zinc is required for structure and function. However, treatment of the dimer with glutathione yields an active monomer (kcat approximately 115 +/- 40 s-1; KM approximately 1.4 +/- 0.4 mM) containing a single zinc ion. The monomer is metastable and slowly reverts to the active dimer in the absence of glutathione. Thus, glyoxalase I appears to be a novel example of a single protein able to exist in two alternative domain-swapped forms. It is unique among domain-swapped proteins in that the active site and an essential metal binding site are apparently disassembled and reassembled by the process of domain swapping. Furthermore, it is the only example to date in which 3D domain swapping can be regulated by a small organic ligand.

  9. Structural characterization suggests models for monomeric and dimeric forms of full-length ezrin.

    PubMed

    Phang, Juanita M; Harrop, Stephen J; Duff, Anthony P; Sokolova, Anna V; Crossett, Ben; Walsh, James C; Beckham, Simone A; Nguyen, Cuong D; Davies, Roberta B; Glöckner, Carina; Bromley, Elizabeth H C; Wilk, Krystyna E; Curmi, Paul M G

    2016-09-15

    Ezrin is a member of the ERM (ezrin-radixin-moesin) family of proteins that have been conserved through metazoan evolution. These proteins have dormant and active forms, where the latter links the actin cytoskeleton to membranes. ERM proteins have three domains: an N-terminal FERM [band Four-point-one (4.1) ERM] domain comprising three subdomains (F1, F2, and F3); a helical domain; and a C-terminal actin-binding domain. In the dormant form, FERM and C-terminal domains form a stable complex. We have determined crystal structures of the active FERM domain and the dormant FERM:C-terminal domain complex of human ezrin. We observe a bistable array of phenylalanine residues in the core of subdomain F3 that is mobile in the active form and locked in the dormant form. As subdomain F3 is pivotal in binding membrane proteins and phospholipids, these transitions may facilitate activation and signaling. Full-length ezrin forms stable monomers and dimers. We used small-angle X-ray scattering to determine the solution structures of these species. As expected, the monomer shows a globular domain with a protruding helical coiled coil. The dimer shows an elongated dumbbell structure that is twice as long as the monomer. By aligning ERM sequences spanning metazoan evolution, we show that the central helical region is conserved, preserving the heptad repeat. Using this, we have built a dimer model where each monomer forms half of an elongated antiparallel coiled coil with domain-swapped FERM:C-terminal domain complexes at each end. The model suggests that ERM dimers may bind to actin in a parallel fashion.

  10. Structure and properties of a truely apo form of AraC dimerization domain.

    PubMed

    Weldon, John E; Rodgers, Michael E; Larkin, Christopher; Schleif, Robert F

    2007-02-15

    The arabinose-binding pockets of wild type AraC dimerization domains crystallized in the absence of arabinose are occupied with the side chains of Y31 from neighboring domains. This interaction leads to aggregation at high solution concentrations and prevents determination of the structure of truely apo AraC. In this work we found that the aggregation does not significantly occur at physiological concentrations of AraC. We also found that the Y31V mutation eliminates the self-association, but does not affect regulation properties of the protein. At the same time, the mutation allows crystallization of the dimerization domain of the protein with only solvent in the arabinose-binding pocket. Using a distance difference method suitable for detecting and displaying even minor structural variation among large groups of similar structures, we find that there is no significant structural change in the core of monomers of the AraC dimerization domain resulting from arabinose, fucose, or tyrosine occupancy of the ligand-binding pocket. A slight change is observed in the relative orientation of monomers in the dimeric form of the domain upon the binding of arabinose but its significance cannot yet be assessed.

  11. A detailed MSn study for the molecular identification of a dimer formed from oxidation of pinene

    NASA Astrophysics Data System (ADS)

    Beck, Martin; Hoffmann, Thorsten

    2016-04-01

    Dimeric products formed in the oxidation of α- and β-pinene have been frequently observed in laboratory and field studies of biogenic SOA formation. While their existence is undoubted, their exact chemical structures remain unclear. This study uses a combined two step approach aiming on the molecular identification of the most important of the various dimers that have been observed in biogenic secondary organic aerosol formation, a dimer with the molecular weight 358 g mol-1. The first step is the application of a functional group derivatization technique (esterification) to quantify the number of carboxylic acid groups in the target molecule. Based on the detailed interpretation of the MSn spectra (up to n = 7) of the derivatized product further information about the exact structure of the compound of interest is compiled. To increase the intensity of precursor ions for the MSn-studies and especially to facilitate successive fragmentation of the target molecule, which yields structurally informative product spectra, cationization reagents (Li+, NH4+) are introduced. The results clearly point to the formation of a dimer containing three carboxylic acid groups and a structure containing a terpenylic acid building block and a pinic acid building block, strongly supporting a structure suggestion by Claeys and coworkers (Yasmeen et al., 2010).

  12. The HPr Proteins from the Thermophile Bacillus stearothermophilus Can Form Domain-swapped Dimers

    SciTech Connect

    Sridharan, Sudharsan; Razvi, Abbas; Scholtz, J. Martin; Sacchettini, James C.

    2010-07-20

    The study of proteins from extremophilic organisms continues to generate interest in the field of protein folding because paradigms explaining the enhanced stability of these proteins still elude us and such studies have the potential to further our knowledge of the forces stabilizing proteins. We have undertaken such a study with our model protein HPr from a mesophile, Bacillus subtilis, and a thermophile, Bacillus stearothermophilus. We report here the high-resolution structures of the wild-type HPr protein from the thermophile and a variant, F29W. The variant proved to crystallize in two forms: a monomeric form with a structure very similar to the wild-type protein as well as a domain-swapped dimer. Interestingly, the structure of the domain-swapped dimer for HPr is very different from that observed for a homologous protein, Crh, from B. subtilis. The existence of a domain-swapped dimer has implications for amyloid formation and is consistent with recent results showing that the HPr proteins can form amyloid fibrils. We also characterized the conformational stability of the thermophilic HPr proteins using thermal and solvent denaturation methods and have used the high-resolution structures in an attempt to explain the differences in stability between the different HPr proteins. Finally, we present a detailed analysis of the solution properties of the HPr proteins using a variety of biochemical and biophysical methods.

  13. Distinct Hepatic Receptors for Low Density Lipoprotein and Apolipoprotein E in Humans

    NASA Astrophysics Data System (ADS)

    Hoeg, Jeffrey M.; Demosky, Stephen J.; Gregg, Richard E.; Schaefer, Ernst J.; Brewer, H. Bryan

    1985-02-01

    Since the liver is a central organ for lipid and lipoprotein synthesis and catabolism, hepatic receptors for specific apolipoproteins on plasma lipoproteins would be expected to modulate lipid and lipoprotein metabolism. The role of hepatic receptors for low density lipoproteins and apolipoprotein E-containing lipoproteins was evaluated in patients with complementary disorders in lipoprotein metabolism: abetalipoproteinemia and homozygous familial hypercholesterolemia. In addition, hepatic membranes from a patient with familial hypercholesterolemia were studied and compared before and after portacaval shunt surgery. The results establish that the human liver has receptors for apolipoproteins B and E. Furthermore, in the human, hepatic receptors for low density lipoproteins and apolipoprotein E are genetically distinct and can undergo independent control.

  14. Association of apolipoprotein E allele {epsilon}4 with late-onset sporadic Alzheimer`s disease

    SciTech Connect

    Lucotte, G.; David, F.; Berriche, S.

    1994-09-15

    Apolipoprotein E, type {epsilon}4 allele (ApoE {epsilon}4), is associated with late-onset sporadic Alzheimer`s disease (AD) in French patients. The association is highly significant (0.45 AD versus 0.12 controls for {epsilon}4 allele frequencies). These data support the involvement of ApoE {epsilon}4 allele as a very important risk factor for the clinical expression of AD. 22 refs., 1 fig., 3 tabs.

  15. Monomeric banana lectin at acidic pH overrules conformational stability of its native dimeric form.

    PubMed

    Khan, Javed M; Qadeer, Atiyatul; Ahmad, Ejaz; Ashraf, Raghib; Bhushan, Bharat; Chaturvedi, Sumit K; Rabbani, Gulam; Khan, Rizwan H

    2013-01-01

    Banana lectin (BL) is a homodimeric protein categorized among jacalin-related family of lectins. The effect of acidic pH was examined on conformational stability of BL by using circular dichroism, intrinsic fluorescence, 1-anilino-8-napthalene sulfonate (ANS) binding, size exclusion chromatography (SEC) and dynamic light scattering (DLS). During acid denaturation of BL, the monomerization of native dimeric protein was found at pH 2.0. The elution profile from SEC showed two different peaks (59.65 ml & 87.98 ml) at pH 2.0 while single peak (61.45 ml) at pH 7.4. The hydrodynamic radii (R h) of native BL was 2.9 nm while at pH 2.0 two species were found with R h of 1.7 and 3.7 nm. Furthermore at, pH 2.0 the secondary structures of BL remained unaltered while tertiary structure was significantly disrupted with the exposure of hydrophobic clusters confirming the existence of molten globule like state. The unfolding of BL with different subunit status was further evaluated by urea and temperature mediated denaturation to check their stability. As inferred from high Cm and ΔG values, the monomeric form of BL offers more resistance towards chemical denaturation than the native dimeric form. Besides, dimeric BL exhibited a Tm of 77°C while no loss in secondary structures was observed in monomers even up to 95°C. To the best of our knowledge, this is the first report on monomeric subunit of lectins showing more stability against denaturants than its native dimeric state.

  16. Stability and photochemistry of ClO dimers formed at low temperature in the gas phase

    NASA Technical Reports Server (NTRS)

    Cox, R. A.; Hayman, G. D.

    1988-01-01

    The recent observations of elevated concentrations of the ClO radical in the austral spring over Antarctica have implicated catalytic destruction by chlorine in the large depletions seen in the total ozone column. One of the chemical theories consistent with an elevated concentration of the ClO is a cycle involving the formation of the ClO dimer through the association reaction: ClO + ClO = Cl2O2 and the photolysis of the dimer to give the active Cl species necessary for O3 depletion. Here, researchers report experimental studies designed to characterize the dimer of ClO formed by the association reaction at low temperatures. ClO was produced by static photolysis of several different precursor systems: Cl sub 2 + O sub 3; Cl sub 2 O sub 2; OClO + Cl sub 2 O spectroscopy in the U.V. region, which allowed the time dependence of Cl sub 2, Cl sub 2 O, ClO, OClO, O sub 3 and other absorbing molecules to be determined.

  17. CNK and HYP form a discrete dimer by their SAM domains to mediate RAF kinase signaling.

    PubMed

    Rajakulendran, Thanashan; Sahmi, Malha; Kurinov, Igor; Tyers, Mike; Therrien, Marc; Sicheri, Frank

    2008-02-26

    RAF kinase functions in the mitogen-activated protein kinase (MAPK) pathway to transmit growth signals to the downstream kinases MEK and ERK. Activation of RAF catalytic activity is facilitated by a regulatory complex comprising the proteins CNK (Connector enhancer of KSR), HYP (Hyphen), and KSR (Kinase Suppressor of Ras). The sterile alpha-motif (SAM) domain found in both CNK and HYP plays an essential role in complex formation. Here, we have determined the x-ray crystal structure of the SAM domain of CNK in complex with the SAM domain of HYP. The structure reveals a single-junction SAM domain dimer of 1:1 stoichiometry in which the binding mode is a variation of polymeric SAM domain interactions. Through in vitro and in vivo mutational analyses, we show that the specific mode of dimerization revealed by the crystal structure is essential for RAF signaling and facilitates the recruitment of KSR to form the CNK/HYP/KSR regulatory complex. We present two docking-site models to account for how SAM domain dimerization might influence the formation of a higher-order CNK/HYP/KSR complex.

  18. [Antirestriction activity of T7 Ocr protein in monomeric and dimeric forms].

    PubMed

    Zavil'gelskiĭ, G B; Kotova, V Iu

    2014-01-01

    The Ocr protein, encoded by 0.3 (ocr) gene of bacteriophage T7, belongs to the family of antirestriction proteins that specifically inhibit the type I restriction-modification systems. Native Ocr forms homodimer (Ocr)2 both in solution and in the crystalline state. The Ocr protein belongs to the family of mimicry proteins. F53D A57E and E53R V77D mutant proteins were obtained, which form monomers. It was shown that the values of the dissociation constants Kd for Ocr, Ocr F53D A57E and Ocr F53RV77D proteins with EcoKI enzyme differ in 1000 times: Kd (Ocr) = 10(-10) M, Kd (Ocr F53D A57E and Ocr F53R V77D) = 10(-7) M. Antimodification activity of the Ocr monomeric forms is significantly reduced. We have shown, that Ocr dimeric form has fundamental importance for high inhibitory activity.

  19. Genetically engineered photoinducible homodimerization system with improved dimer-forming efficiency.

    PubMed

    Nihongaki, Yuta; Suzuki, Hideyuki; Kawano, Fuun; Sato, Moritoshi

    2014-03-21

    Vivid (VVD) is a photoreceptor derived from Neurospora Crassa that rapidly forms a homodimer in response to blue light. Although VVD has several advantages over other photoreceptors as photoinducible homodimerization system, VVD has a critical limitation in its low dimer-forming efficiency. To overcome this limitation of wild-type VVD, here we conduct site-directed saturation mutagenesis in the homodimer interface of VVD. We have found that the Ile52Cys mutation of VVD (VVD-52C) substantially improves its homodimer-forming efficiency up to 180%. We have demonstrated the utility of VVD-52C for making a light-inducible gene expression system more robust. In addition, using VVD-52C, we have developed photoactivatable caspase-9, which enables optical control of apoptosis of mammalian cells. The present genetically engineered photoinducible homodimerization system can provide a powerful tool to optically control a broad range of molecular processes in the cell.

  20. Application of denaturing gradient gel electrophoresis to detect DNA sequence differences encoding apolipoprotein E isoforms

    SciTech Connect

    Parker, S.; Angelico, M.C.; Laffel, L.; Krolewski, A.S. Harvard Medical School, Boston, MA )

    1993-04-01

    Apolipoprotein E (apoE) plays an important role in plasma lipid metabolism. Three common isoforms of this protein have been identified by the isoelectric focusing method. In this report the authors describe a new method for distinguishing these isoforms. Their method employs PCR amplification of the DNA sequence of exon 4 in the apoE gene followed by denaturing gradient gel electrophoresis (DGGE) to distinguish its different melting characteristics. Identification of the ApoE isoforms through DNA melting behavior rather than protein charge differences eliminates the problems associated with isoelectric focusing and facilitates screening for additional mutations at the apoE locus. 12 refs., 2 figs.

  1. Analysis of cell surface alterations in Legionella pneumophila cells treated with human apolipoprotein E.

    PubMed

    Palusinska-Szysz, Marta; Zdybicka-Barabas, Agnieszka; Cytryńska, Małgorzata; Wdowiak-Wróbel, Sylwia; Chmiel, Elżbieta; Gruszecki, Wiesław I

    2015-03-01

    Binding of human apolipoprotein E (apoE) to Legionella pneumophila lipopolysaccharide was analysed at the molecular level by Fourier-transform infrared spectroscopy, thereby providing biophysical evidence for apoE-L. pneumophila lipopolysaccharide interaction. Atomic force microscopy imaging of apoE-exposed L. pneumophila cells revealed alterations in the bacterial cell surface topography and nanomechanical properties in comparison with control bacteria. The changes induced by apoE binding to lipopolysaccharide on the surface of L. pneumophila cells may participate in: (1) impeding the penetration of host cells by the bacteria; (2) suppression of pathogen intracellular growth and eventually; and (3) inhibition of the development of infection.

  2. The multidrug resistance efflux complex, EmrAB from Escherichia coli forms a dimer in vitro

    SciTech Connect

    Tanabe, Mikio; Szakonyi, Gerda; Brown, Katherine A.; Henderson, Peter J.F.; Nield, Jon; Byrne, Bernadette

    2009-03-06

    Tripartite efflux systems are responsible for the export of toxins across both the inner and outer membranes of Gram negative bacteria. Previous work has indicated that EmrAB-TolC from Escherichia coli is such a tripartite system, comprised of EmrB an MFS transporter, EmrA, a membrane fusion protein and TolC, an outer membrane channel. The whole complex is predicted to form a continuous channel allowing direct export from the cytoplasm to the exterior of the cell. Little is known, however, about the interactions between the individual components of this system. Reconstitution of EmrA + EmrB resulted in co-elution of the two proteins from a gel filtration column indicating formation of the EmrAB complex. Electron microscopic single particle analysis of the reconstituted EmrAB complex revealed the presence of particles approximately 240 x 140 A, likely to correspond to two EmrAB dimers in a back-to-back arrangement, suggesting the dimeric EmrAB form is the physiological state contrasting with the trimeric arrangement of the AcrAB-TolC system.

  3. Packing interface energetics in different crystal forms of the λ Cro dimer.

    PubMed

    Ahlstrom, Logan S; Miyashita, Osamu

    2014-07-01

    Variation among crystal structures of the λ Cro dimer highlights conformational flexibility. The structures range from a wild type closed to a mutant fully open conformation, but it is unclear if each represents a stable solution state or if one may be the result of crystal packing. Here we use molecular dynamics (MD) simulation to investigate the energetics of crystal packing interfaces and the influence of site-directed mutagenesis on them in order to examine the effect of crystal packing on wild type and mutant Cro dimer conformation. Replica exchange MD of mutant Cro in solution shows that the observed conformational differences between the wild type and mutant protein are not the direct consequence of mutation. Instead, simulation of Cro in different crystal environments reveals that mutation affects the stability of crystal forms. Molecular Mechanics Poisson-Boltzmann Surface Area binding energy calculations reveal the detailed energetics of packing interfaces. Packing interfaces can have diverse properties in strength, energetic components, and some are stronger than the biological dimer interface. Further analysis shows that mutation can strengthen packing interfaces by as much as ∼5 kcal/mol in either crystal environment. Thus, in the case of Cro, mutation provides an additional energetic contribution during crystal formation that may stabilize a fully open higher energy state. Moreover, the effect of mutation in the lattice can extend to packing interfaces not involving mutation sites. Our results provide insight into possible models for the effect of crystallization on Cro conformational dynamics and emphasize careful consideration of protein crystal structures.

  4. Biochemical, Mutational and In Silico Structural Evidence for a Functional Dimeric Form of the Ornithine Decarboxylase from Entamoeba histolytica

    PubMed Central

    Preeti; Tapas, Satya; Kumar, Pravindra; Madhubala, Rentala; Tomar, Shailly

    2012-01-01

    Background Entamoeba histolytica is responsible for causing amoebiasis. Polyamine biosynthesis pathway enzymes are potential drug targets in parasitic protozoan diseases. The first and rate-limiting step of this pathway is catalyzed by ornithine decarboxylase (ODC). ODC enzyme functions as an obligate dimer. However, partially purified ODC from E. histolytica (EhODC) is reported to exist in a pentameric state. Methodology and Results In present study, the oligomeric state of EhODC was re-investigated. The enzyme was over-expressed in Escherichia coli and purified. Pure protein was used for determination of secondary structure content using circular dichroism spectroscopy. The percentages of α-helix, β-sheets and random coils in EhODC were estimated to be 39%, 25% and 36% respectively. Size-exclusion chromatography and mass spectrophotometry analysis revealed that EhODC enzyme exists in dimeric form. Further, computational model of EhODC dimer was generated. The homodimer contains two separate active sites at the dimer interface with Lys57 and Cys334 residues of opposite monomers contributing to each active site. Molecular dynamic simulations were performed and the dimeric structure was found to be very stable with RMSD value ∼0.327 nm. To gain insight into the functional role, the interface residues critical for dimerization and active site formation were identified and mutated. Mutation of Lys57Ala or Cys334Ala completely abolished enzyme activity. Interestingly, partial restoration of the enzyme activity was observed when inactive Lys57Ala and Cys334Ala mutants were mixed confirming that the dimer is the active form. Furthermore, Gly361Tyr and Lys157Ala mutations at the dimer interface were found to abolish the enzyme activity and destabilize the dimer. Conclusion To our knowledge, this is the first report which demonstrates that EhODC is functional in the dimeric form. These findings and availability of 3D structure model of EhODC dimer opens up

  5. Vitamin D Binding Protein Isoforms and Apolipoprotein E in Cerebrospinal Fluid as Prognostic Biomarkers of Multiple Sclerosis

    PubMed Central

    Lis, Katarzyna; Minari, Nicoletta; Falvo, Sara; Marnetto, Fabiana; Caldano, Marzia; Reviglione, Raffaella; Berchialla, Paola; Capobianco, Marco A.; Malentacchi, Maria; Corpillo, Davide; Bertolotto, Antonio

    2015-01-01

    Background Multiple sclerosis (MS) is a multifactorial autoimmune disease of the central nervous system with a heterogeneous and unpredictable course. To date there are no prognostic biomarkers even if they would be extremely useful for early patient intervention with personalized therapies. In this context, the analysis of inter-individual differences in cerebrospinal fluid (CSF) proteome may lead to the discovery of biological markers that are able to distinguish the various clinical forms at diagnosis. Methods To this aim, a two dimensional electrophoresis (2-DE) study was carried out on individual CSF samples from 24 untreated women who underwent lumbar puncture (LP) for suspected MS. The patients were clinically monitored for 5 years and then classified according to the degree of disease aggressiveness and the disease-modifying therapies prescribed during follow up. Results The hierarchical cluster analysis of 2-DE dataset revealed three protein spots which were identified by means of mass spectrometry as Apolipoprotein E (ApoE) and two isoforms of vitamin D binding protein (DBP). These three protein spots enabled us to subdivide the patients into subgroups correlated with clinical classification (MS aggressive forms identification: 80%). In particular, we observed an opposite trend of values for the two protein spots corresponding to different DBP isoforms suggesting a role of a post-translational modification rather than the total protein content in patient categorization. Conclusions These findings proved to be very interesting and innovative and may be developed as new candidate prognostic biomarkers of MS aggressiveness, if confirmed. PMID:26046356

  6. A rapid flat gel isoelectric focusing method for the determination of apolipoprotein E phenotypes and its application.

    PubMed

    Eto, M; Watanabe, K; Ishii, K

    1985-06-30

    A rapid flat gel isoelectric focusing method has been developed for the determination of apolipoprotein E phenotypes. Isoelectric focusing in 5% polyacrylamide flat gel with 8 mol/l urea and 2.8% pharmalyte (pH 4-6.5) was carried out at 3,000 V and 4 degrees C for 1 h under a constant power of 30 W. The separation of apolipoprotein E isoproteins was good and the isoelectric points were determined. Using this method, the apolipoprotein E phenotype frequency was examined in the Japanese population, and a higher frequency of phenotype E3/3 and a lower frequency of phenotype E3/2 were found in Japanese than those reported for the German, American or English population. In our focusing system the cut-off point of apolipoprotein E2/E3 ratio between the phenotype E3/3 and E3/2 was assumed to be approximately 0.9. These results indicate that this method may be useful for the determination of apolipoprotein E phenotypes.

  7. The export receptor Crm1 forms a dimer to promote nuclear export of HIV RNA.

    PubMed

    Booth, David S; Cheng, Yifan; Frankel, Alan D

    2014-12-08

    The HIV Rev protein routes viral RNAs containing the Rev Response Element (RRE) through the Crm1 nuclear export pathway to the cytoplasm where viral proteins are expressed and genomic RNA is delivered to assembling virions. The RRE assembles a Rev oligomer that displays nuclear export sequences (NESs) for recognition by the Crm1-Ran(GTP) nuclear receptor complex. Here we provide the first view of an assembled HIV-host nuclear export complex using single-particle electron microscopy. Unexpectedly, Crm1 forms a dimer with an extensive interface that enhances association with Rev-RRE and poises NES binding sites to interact with a Rev oligomer. The interface between Crm1 monomers explains differences between Crm1 orthologs that alter nuclear export and determine cellular tropism for viral replication. The arrangement of the export complex identifies a novel binding surface to possibly target an HIV inhibitor and may point to a broader role for Crm1 dimerization in regulating host gene expression.

  8. A new bright green-emitting fluorescent protein: Engineered monomeric and dimeric forms

    PubMed Central

    Ilagan, Robielyn P.; Rhoades, Elizabeth; Gruber, David F.; Kao, Hung-Teh; Pieribone, Vincent A.; Regan, Lynne

    2010-01-01

    Summary Fluorescent proteins (FP) have become essential tools in molecular and biological applications. Here, we present a novel fluorescent protein isolated from warm water coral, Cyphastrea microphthalma. The protein, which we named VFP (vivid Verde FP), matures readily at 37 °C and emits bright green light. Further characterizations revealed that VFP has a tendency to form dimers. By creating a homology model of VFP, based on the structure of red fluorescent protein DsRed, we were able to make mutations that alter the protein’s oligomerization state. We present two proteins, mVFP and mVFP1, that are both exclusively monomeric, and one, dVFP, which is dimeric. We characterized the spectroscopic properties of VFP and its variants in comparison with enhance green fluorescent protein (EGFP), a widely use variant of GFP. All the VFP variants are at least twice as bright as EGFP. Finally, we demonstrate the effectiveness of the VFP variants both in vitro and in vivo detection applications. PMID:20345907

  9. Rigid dimers formed through strong interdigitated H-bonds yield compact 1D supramolecular helical polymers.

    PubMed

    Ciesielski, Artur; Stefankiewicz, Artur R; Hanke, Felix; Persson, Mats; Lehn, Jean-Marie; Samorì, Paolo

    2011-02-07

    Hierarchical self-assembly of small abiotic molecular modules interacting through noncovalent forces is increasingly being used to generate functional structures and materials for electronic, catalytic, and biomedical applications. The greatest control over the geometry in H-bond supramolecular architectures, especially in H-bonded supramolecular polymers, can be achieved by using conformationally rigid molecular modules undergoing self-assembly through strong H-bonds. Their binding strength depends on the multiplicity of the H-bonds, the nature of donor/acceptor pairs and their secondary attractive/repulsive interactions. Here a functionalized molecular module is described, which is capable of self-associating through self-complementary H-bonding patterns comprising four strong and two medium-strength H-bonds to form dimers. The self-association of these phenylpyrimidine-based dimers through directional H-bonding between two lateral pyridin-2(1H)-one units of neighboring molecules allows the formation of highly compact 1D supramolecular polymers by self-assembly on graphite. A concentration-dependent study by scanning tunneling microscopy at the solid-liquid interface, corroborated by dispersion-corrected density functional studies, reveals the controlled generation of either linear supramolecular 2D arrays, or long helical supramolecular polymers with a high shape persistence.

  10. Cystatin C deficiency increases elastic lamina degradation and aortic dilatation in apolipoprotein E-null mice.

    PubMed

    Sukhova, Galina K; Wang, Bing; Libby, Peter; Pan, Jie-Hong; Zhang, Yaou; Grubb, Anders; Fang, Kenneth; Chapman, Harold A; Shi, Guo-Ping

    2005-02-18

    The pathogenesis of atherosclerosis and abdominal aortic aneurysm involves substantial proteolysis of the arterial extracellular matrix. The lysosomal cysteine proteases can exert potent elastolytic and collagenolytic activity. Human atherosclerotic plaques have increased cysteine protease content and decreased levels of the endogenous inhibitor cystatin C, suggesting an imbalance that would favor matrix degradation in the arterial wall. This study tested directly the hypothesis that impaired expression of cystatin C alters arterial structure. Cystatin C-deficient mice (Cyst C-/-) were crossbred with apolipoprotein E-deficient mice (ApoE-/-) to generate cystatin C and apolipoprotein E-double deficient mice (Cyst C-/-ApoE-/-). After 12 weeks on an atherogenic diet, cystatin C deficiency yielded significantly increased tunica media elastic lamina fragmentation, decreased medial size, and increased smooth muscle cell and collagen content in aortic lesions of ApoE-/- mice. Cyst C-/-ApoE-/- mice also showed dilated thoracic and abdominal aortae compared with control ApoE-/- mice, although atheroma lesion size, intimal macrophage accumulation, and lipid core size did not differ between these mice. These findings demonstrate directly the importance of cysteine protease/protease inhibitor balance in dysregulated arterial integrity and remodeling during experimental atherogenesis.

  11. Pallidal neuronal apolipoprotein E in pantothenate kinase-associated neurodegeneration recapitulates ischemic injury to the globuspallidus

    PubMed Central

    Woltjer, Randall L.; Reese, Lindsay C.; Richardson, Brian E.; Tran, Huong; Green, Sarah; Pham, Thao; Chalupsky, Megan; Gabriel, Isabella; Light, Tyler; Sanford, Lynn; Jeong, Suh Y.; Hamada, Jeffrey; Schwanemann, Leila K.; Rogers, Caleb; Gregory, Allison; Hogarth, Penelope; Hayflick, Susan J.

    2015-01-01

    Pantothenate kinase-associated neurodegeneration (PKAN) is a progressive movement disorder that is due to mutations in PANK2. Pathologically, it is a member of a class of diseases known as neurodegeneration with brain iron accumulation (NBIA) and features increased tissue iron and ubiquitinated protein aceous aggregates in the globuspallidus. We have previously determined that these aggregates represent condensed residue derived from degenerated pallidal neurons. However, the protein content, other than ubiquitin, of these aggregates remains unknown. In the present study, we performed biochemical and immunohistochemical studies to characterize these aggregates and found them to be enriched in apolipoprotein E that is poorly soluble in detergent solutions. However, did not determine a significant association between APOE genotype and the clinical phenotype of disease in our database of 81 cases. Rather, we frequently identified similar ubiquitin- and apolipoprotein E-enriched lesions in these neurons in non-PKAN patients in the penumbrae of remote infarcts that involve the globuspallidus, and occasionally in other brain sites that contain large γ-aminobutyric acid (GABA)ergic neurons. Our findings, taken together, suggest that tissue or cellular hypoxic/ischemic injury within the globuspallidus may underlie the pathogenesis of PKAN. PMID:26547561

  12. Altered Energy Metabolism Pathways in the Posterior Cingulate in Young Adult Apolipoprotein E ɛ4 Carriers

    PubMed Central

    Perkins, Michelle; Wolf, Andrew B.; Chavira, Bernardo; Shonebarger, Daniel; Meckel, J.P.; Leung, Lana; Ballina, Lauren; Ly, Sarah; Saini, Aman; Jones, T. Bucky; Vallejo, Johana; Jentarra, Garilyn; Valla, Jon

    2016-01-01

    The APOE gene, encoding apolipoprotein E, is the primary genetic risk factor for late-onset Alzheimer’s disease (AD). Apolipoprotein E ɛ4 allele (APOE4) carriers have alterations in brain structure and function (as measured by brain imaging) even as young adults. Examination of this population is valuable in further identifying details of these functional changes and their association with vulnerability to AD decades later. Previous work demonstrates functional declines in mitochondrial activity in the posterior cingulate cortex, a key region in the default mode network, which appears to be strongly associated with functional changes relevant to AD risk. Here, we demonstrate alterations in the pathways underlying glucose, ketone, and mitochondrial energy metabolism. Young adult APOE4 carriers displayed upregulation of specific glucose (GLUT1 & GLUT3) and monocarboxylate (MCT2) transporters, the glucose metabolism enzyme hexokinase, the SCOT & AACS enzymes involved in ketone metabolism, and complexes I, II, and IV of the mitochondrial electron transport chain. The monocarboxylate transporter (MCT4) was found to be downregulated in APOE4 carriers. These data suggest that widespread dysregulation of energy metabolism in this at-risk population, even decades before possible disease onset. Therefore, these findings support the idea that alterations in brain energy metabolism may contribute significantly to the risk that APOE4 confers for AD. PMID:27128370

  13. [Relationship between apolipoprotein E polymorphism and cognitive function in patients with primary hypertension].

    PubMed

    Su, Yanling; Chen, Xiaoping; Huang, Yan; Jiang, Lingyun; Huang, He

    2009-08-01

    To explore the relationship between apolipoprotein E polymorphism and cognitive function in primary hypertension patients, we collected 200 Chinese primary hypertensive patients. Blood pressure (BP), heart rate (HR), height, body weight, waistline, hip circumference were measured. The Mini Mental State Examination (MMSE) was applied to test the cognitive function and compute score. Full-automatic bio-chemistry analyzer was used to determine total cholesterol (TC) and triglyeride (TG) and fasting glucose. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP) was used for the analysis of the apolipoprotein E polymorphism. We found that in primary hypertension patients, the genotype frequency of epsilon3/4 and epsilon4/4 were significantly higher in the cognitive impairment group than that in the cognitive normal group. The allele frequency of e4 is obviously higher in the cognitive impairment group than that in the cognitive normal group. Age and epsilon4/4 genetype were positively correlated with hypertensive-cognitive impairment, while cultural level was negtively correlated with it. ApoEepsilon4 allele and age might be risk factors for the cognitive impairment in hypertensive patients. The epsilon4 homozygote (epsilon4/4) might be an important influencing factor for the progression of cognitive impairment.

  14. Suppressive effects of cacao polyphenols on the development of atherosclerosis in apolipoprotein E-deficient mice.

    PubMed

    Natsume, Midori; Baba, Seigo

    2014-01-01

    Previous studies in humans have shown that the cacao polyphenols, (-)-epicatechin and its oligomers, prevent in vitro and ex vivo low-density lipoprotein oxidation mediated by free radical generators and metal ions and also reduce plasma LDL-cholesterol levels. The aim of this study was to examine the effects of cacao polyphenols on the development of atherosclerosis in apolipoprotein E-deficient (-/-) mice. Mice aged 8 weeks (n = 90) were randomized into three groups, and fed either normal mouse chow (controls) or chow supplemented with 0.25 or 0.40 % cacao polyphenols for 16 weeks. The mean plaque area in cross-sections of the brachiocephalic trunk was measured and found to be lower in the 0.25 % cacao polyphenol group than in the control group (p < 0.05). Pathological observations showed that accumulation of cholesterol crystals in the plaque area was greater in the control group compared with the 0.40 % cacao polyphenol group (p < 0.05). Immunochemical staining in the 0.25 and 0.40 % groups showed that expression of the cell adhesion molecules (VCAM-1 and ICAM-1) and production of oxidative stress markers (4-hydroxynonenal, hexanoyl-lysine, and dityrosine) were reduced in cross-sections of the brachiocephalic trunk. These results suggest that cacao polyphenols inhibit the development of atherosclerosis in apolipoprotein E-deficient (-/-) mice by reducing oxidative stress and inflammatory responses.

  15. An ABCA1-independent pathway for recycling a poorly lipidated 8.1 nm apolipoprotein E particle from glia

    PubMed Central

    Fan, Jianjia; Stukas, Sophie; Wong, Charmaine; Chan, Jennifer; May, Sharon; DeValle, Nicole; Hirsch-Reinshagen, Veronica; Wilkinson, Anna; Oda, Michael N.; Wellington, Cheryl L.

    2011-01-01

    Lipid transport in the brain is coordinated by glial-derived lipoproteins that contain apolipoprotein E (apoE) as their primary protein. Here we show that apoE is secreted from wild-type (WT) primary murine mixed glia as nascent lipoprotein subspecies ranging from 7.5 to 17 nm in diameter. Negative-staining electron microscropy (EM) revealed rouleaux, suggesting a discoidal structure. Potassium bromide (KBr) density gradient ultracentrifugation showed that all subspecies, except an 8.1 nm particle, were lipidated. Glia lacking the cholesterol transporter ABCA1 secreted only 8.1 nm particles, which were poorly lipidated and nondiscoidal but could accept lipids to form the full repertoire of WT apoE particles. Receptor-associated-protein (RAP)-mediated inhibition of apoE receptor function blocked appearance of the 8.1 nm species, suggesting that this particle may arise through apoE recycling. Selective deletion of the LDL receptor (LDLR) reduced the level of 8.1 nm particle production by approximately 90%, suggesting that apoE is preferentially recycled through the LDLR. Finally, apoA-I stimulated secretion of 8.1 nm particles in a dose-dependent manner. These results suggest that nascent glial apoE lipoproteins are secreted through multiple pathways and that a greater understanding of these mechanisms may be relevant to several neurological disorders. PMID:21705806

  16. Syndecan 4 Is Involved in Mediating HCV Entry through Interaction with Lipoviral Particle-Associated Apolipoprotein E

    PubMed Central

    Lefèvre, Mathieu; Felmlee, Daniel J.; Parnot, Marie; Baumert, Thomas F.; Schuster, Catherine

    2014-01-01

    Hepatitis C virus (HCV) is a major cause of liver disease worldwide and HCV infection represents a major health problem. HCV associates with host lipoproteins forming host/viral hybrid complexes termed lipoviral particles. Apolipoprotein E (apoE) is a lipoprotein component that interacts with heparan sulfate proteoglycans (HSPG) to mediate hepatic lipoprotein uptake, and may likewise mediate HCV entry. We sought to define the functional regions of apoE with an aim to identify critical apoE binding partners involved in HCV infection. Using adenoviral vectors and siRNA to modulate apoE expression we show a direct correlation of apoE expression and HCV infectivity, whereas no correlation exists with viral protein expression. Mutating the HSPG binding domain (HSPG-BD) of apoE revealed key residues that are critical for mediating HCV infection. Furthermore, a novel synthetic peptide that mimics apoE’s HSPG-BD directly and competitively inhibits HCV infection. Genetic knockdown of the HSPG proteins syndecan (SDC) 1 and 4 revealed that SDC4 principally mediates HCV entry. Our data demonstrate that HCV uses apoE-SDC4 interactions to enter hepatoma cells and establish infection. Targeting apoE-SDC interactions could be an alternative strategy for blocking HCV entry, a critical step in maintaining chronic HCV infection. PMID:24751902

  17. High levels of homocysteine downregulate apolipoprotein E expression via nuclear factor kappa B

    PubMed Central

    Trusca, Violeta G; Mihai, Adina D; Fuior, Elena V; Fenyo, Ioana M; Gafencu, Anca V

    2016-01-01

    AIM: To investigate the effect of high homocysteine (Hcy) levels on apolipoprotein E (apoE) expression and the signaling pathways involved in this gene regulation. METHODS: Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot were used to assess apoE expression in cells treated with various concentrations (50-500 μmol/L) of Hcy. Calcium phosphate-transient transfections were performed in HEK-293 and RAW 264.7 cells to evaluate the effect of Hcy on apoE regulatory elements [promoter and distal multienhancer 2 (ME2)]. To this aim, plasmids containing the proximal apoE promoter [(-500/+73)apoE construct] alone or in the presence of ME2 [ME2/(-500/+73)apoE construct] to drive the expression of the reporter luciferase gene were used. Co-transfection experiments were carried out to investigate the downstream effectors of Hcy-mediated regulation of apoE promoter by using specific inhibitors or a dominant negative form of IKβ. In other co-transfections, the luciferase reporter was under the control of synthetic promoters containing multiple specific binding sites for nuclear factor kappa B (NF-κB), activator protein-1 (AP-1) or nuclear factor of activated T cells (NFAT). Chromatin immunoprecipitation (ChIP) assay was accomplished to detect the binding of NF-κB p65 subunit to the apoE promoter in HEK-293 treated with 500 μmol/L Hcy. As control, cells were incubated with similar concentration of cysteine. NF-κB p65 proteins bound to DNA were immunoprecipitated with anti-p65 antibodies and DNA was identified by PCR using primers amplifying the region -100/+4 of the apoE gene. RESULTS: RT-PCR revealed that high levels of Hcy (250-750 μmol/L) induced a 2-3 fold decrease in apoE mRNA levels in HEK-293 cells, while apoE gene expression was not significantly affected by treatment with lower concentrations of Hcy (100 μmol/L). Immunoblotting data provided additional evidence for the negative role of Hcy in apoE expression. Hcy decreased apoE promoter

  18. Structure, Aggregation, and Activity of a Covalent Insulin Dimer Formed During Storage of Neutral Formulation of Human Insulin.

    PubMed

    Hjorth, Christian Fogt; Norrman, Mathias; Wahlund, Per-Olof; Benie, Andrew J; Petersen, Bent O; Jessen, Christian M; Pedersen, Thomas Å; Vestergaard, Kirsten; Steensgaard, Dorte B; Pedersen, Jan Skov; Naver, Helle; Hubálek, František; Poulsen, Christian; Otzen, Daniel

    2016-04-01

    A specific covalently linked dimeric species of insulin high molecular weight products (HMWPs), formed during prolonged incubation of a neutral pharmaceutical formulation of human insulin, were characterized in terms of tertiary structure, self-association, biological activity, and fibrillation properties. The dimer was formed by a covalent link between A21Asn and B29Lys. It was analyzed using static and dynamic light scattering and small-angle X-ray scattering to evaluate its self-association behavior. The tertiary structure was obtained using nuclear magnetic resonance and X-ray crystallography. The biological activity of HMWP was determined using 2 in vitro assays, and its influence on fibrillation was investigated using Thioflavin T assays. The dimer's tertiary structure was nearly identical to that of the noncovalent insulin dimer, and it was able to form hexamers in the presence of zinc. The dimer exhibited reduced propensity for self-association in the absence of zinc but significantly postponed the onset of fibrillation in insulin formulations. Consistent with its dimeric state, the tested species of HMWP showed little to no biological activity in the used assays. This study is the first detailed characterization of a specific type of human insulin HMWP formed during storage of a marketed pharmaceutical formulation. These results indicate that this specific type of HMWP is unlikely to antagonize the physical stability of the formulation, as HMWP retained a tertiary structure similar to the noncovalent dimer and participated in hexamer assembly in the presence of zinc. In addition, increasing amounts of HMWP reduce the rate of insulin fibrillation.

  19. No association between apolipoprotein E or N‐Acetyltransferase 2 gene polymorphisms and age‐related hearing loss

    PubMed Central

    Dawes, Piers; Platt, Hazel; Horan, Michael; Ollier, William; Munro, Kevin; Pendleton, Neil

    2014-01-01

    Objectives/Hypothesis Age‐related hearing loss has a genetic component, but there have been limited genetic studies in this field. Both N‐acetyltransferase 2 and apolipoprotein E genes have previously been associated. However, these studies have either used small sample sizes, examined a limited number of polymorphisms, or have produced conflicting results. Here we use a haplotype tagging approach to determine association with age‐related hearing loss and investigate epistasis between these two genes. Study Design Candidate gene association study of a continuous phenotype. Methods We investigated haplotype tagging single nucleotide polymorphisms in the N‐acetyltransferase 2 gene and the presence/absence of the apolipoprotein E ε4 allele for association with age‐related hearing loss in a cohort of 265 Caucasian elderly volunteers from Greater Manchester, United Kingdom. Hearing phenotypes were generated using principal component analysis of the hearing threshold levels for the better ear (severity, slope, and concavity). Genotype data for the N‐acetyltransferase 2 gene was obtained from existing genome‐wide association study data from the Illumina 610‐Quadv1 chip. Apolipoprotein E genotyping was performed using Sequenom technology. Linear regression analysis was performed using Plink and Stata software. Results No significant associations (P value, > 0.05) were observed between the N‐acetyltransferase 2 or apolipoprotein E gene polymorphisms and any hearing factor. No significant association was observed for epistasis analysis of apolipoprotein E ε4 and the N‐acetyltransferase 2 single nucleotide polymorphism rs1799930 (NAT2*6A). Conclusion We found no evidence to support that either N‐acetyltransferase 2 or apolipoprotein E gene polymorphisms are associated with age‐related hearing loss in a cohort of 265 elderly volunteers. Level of Evidence N/A. Laryngoscope, 125:E33–E38, 2015 PMID:25155015

  20. Apolipoprotein E4 influences growth and cognitive responses to micronutrient supplementation in shantytown children from northeast Brazil

    PubMed Central

    Mitter, Sumeet S.; Oriá, Reinaldo B.; Kvalsund, Michelle P.; Pamplona, Paula; Joventino, Emanuella Silva; Mota, Rosa M. S.; Gonçalves, Davi C.; Patrick, Peter D.; Guerrant, Richard L.; Lima, Aldo A. M.

    2012-01-01

    OBJECTIVE: Apolipoprotein E4 may benefit children during early periods of life when the body is challenged by infection and nutritional decline. We examined whether apolipoprotein E4 affects intestinal barrier function, thereby improving short-term growth and long-term cognitive outcomes in Brazilian shantytown children. METHODS: A total of 213 Brazilian shantytown children with below-median height-for-age z-scores (HAZ) received 200,000 IU of retinol (every four months), zinc (40 mg twice weekly), or both for one year, with half of each group receiving glutamine supplementation for 10 days. Height-for-age z-scores, weight-for-age z-scores, weight-for-height z-scores, and lactulose:mannitol ratios were assessed during the initial four months of treatment. An average of four years (range 1.4-6.6) later, the children underwent cognitive testing to evaluate non-verbal intelligence, coding, verbal fluency, verbal learning, and delayed verbal learning. Apolipoprotein E4 carriage was determined by PCR analysis for 144 children. RESULTS: Thirty-seven children were apolipoprotein E4(+), with an allele frequency of 13.9%. Significant associations were found for vitamin A and glutamine with intestinal barrier function. Apolipoprotein E4(+) children receiving glutamine presented significant positive Pearson correlations between the change in height-for-age z-scores over four months and delayed verbal learning, along with correlated changes over the same period in weight-for-age z-scores and weight-for-height z-scores associated with non-verbal intelligence quotients. There was a significant correlation between vitamin A supplementation of apolipoprotein E4(+) children and improved delta lactulose/mannitol. Apolipoprotein E4(-) children, regardless of intervention, exhibited negative Pearson correlations between the change in lactulose-to-mannitol ratio over four months and verbal learning and non-verbal intelligence. CONCLUSIONS: During development, apolipoprotein E4 may

  1. Euglena gracilis ascorbate peroxidase forms an intramolecular dimeric structure: its unique molecular characterization.

    PubMed

    Ishikawa, Takahiro; Tajima, Naoko; Nishikawa, Hitoshi; Gao, Yongshun; Rapolu, Madhusudhan; Shibata, Hitoshi; Sawa, Yoshihiro; Shigeoka, Shigeru

    2010-02-09

    Euglena gracilis lacks a catalase and contains a single APX (ascorbate peroxidase) and enzymes related to the redox cycle of ascorbate in the cytosol. In the present study, a full-length cDNA clone encoding the Euglena APX was isolated and found to contain an open reading frame encoding a protein of 649 amino acids with a calculated molecular mass of 70.5 kDa. Interestingly, the enzyme consisted of two entirely homologous catalytic domains, designated APX-N and APX-C, and an 102 amino acid extension in the N-terminal region, which had a typical class II signal proposed for plastid targeting in Euglena. A computer-assisted analysis indicated a novel protein structure with an intramolecular dimeric structure. The analysis of cell fractionation showed that the APX protein is distributed in the cytosol, but not the plastids, suggesting that Euglena APX becomes mature in the cytosol after processing of the precursor. The kinetics of the recombinant mature FL (full-length)-APX and the APX-N and APX-C domains with ascorbate and H2O2 were almost the same as that of the native enzyme. However, the substrate specificity of the mature FL-APX and the native enzyme was different from that of APX-N and APX-C. The mature FL-APX, but not the truncated forms, could reduce alkyl hydroperoxides, suggesting that the dimeric structure is correlated with substrate recognition. In Euglena cells transfected with double-stranded RNA, the silencing of APX expression resulted in a significant increase in the cellular level of H2O2, indicating the physiological importance of APX to the metabolism of H2O2.

  2. Tor forms a dimer through an N-terminal helical solenoid with a complex topology.

    PubMed

    Baretić, Domagoj; Berndt, Alex; Ohashi, Yohei; Johnson, Christopher M; Williams, Roger L

    2016-04-13

    The target of rapamycin (Tor) is a Ser/Thr protein kinase that regulates a range of anabolic and catabolic processes. Tor is present in two complexes, TORC1 and TORC2, in which the Tor-Lst8 heterodimer forms a common sub-complex. We have determined the cryo-electron microscopy (EM) structure of Tor bound to Lst8. Two Tor-Lst8 heterodimers assemble further into a dyad-symmetry dimer mediated by Tor-Tor interactions. The first 1,300 residues of Tor form a HEAT repeat-containing α-solenoid with four distinct segments: a highly curved 800-residue N-terminal 'spiral', followed by a 400-residue low-curvature 'bridge' and an extended 'railing' running along the bridge leading to the 'cap' that links to FAT region. This complex topology was verified by domain insertions and offers a new interpretation of the mTORC1 structure. The spiral of one TOR interacts with the bridge of another, which together form a joint platform for the Regulatory Associated Protein of TOR (RAPTOR) regulatory subunit.

  3. Tor forms a dimer through an N-terminal helical solenoid with a complex topology

    NASA Astrophysics Data System (ADS)

    Baretić, Domagoj; Berndt, Alex; Ohashi, Yohei; Johnson, Christopher M.; Williams, Roger L.

    2016-04-01

    The target of rapamycin (Tor) is a Ser/Thr protein kinase that regulates a range of anabolic and catabolic processes. Tor is present in two complexes, TORC1 and TORC2, in which the Tor-Lst8 heterodimer forms a common sub-complex. We have determined the cryo-electron microscopy (EM) structure of Tor bound to Lst8. Two Tor-Lst8 heterodimers assemble further into a dyad-symmetry dimer mediated by Tor-Tor interactions. The first 1,300 residues of Tor form a HEAT repeat-containing α-solenoid with four distinct segments: a highly curved 800-residue N-terminal 'spiral', followed by a 400-residue low-curvature 'bridge' and an extended `railing' running along the bridge leading to the 'cap' that links to FAT region. This complex topology was verified by domain insertions and offers a new interpretation of the mTORC1 structure. The spiral of one TOR interacts with the bridge of another, which together form a joint platform for the Regulatory Associated Protein of TOR (RAPTOR) regulatory subunit.

  4. Monocytic elastase-mediated apolipoprotein-E degradation: Potential involvement of microglial elastase-like proteases in apolipoprotein-E proteolysis in brains with Alzheimers disease.

    PubMed

    Suenaga, Midori; Furuta, Akiko; Wakabayashi, Koichi; Saibara, Toshiji; Matsunaga, Yoichi

    2015-08-01

    Impaired clearance of soluble Aβ (amyloid-β) promotes Aβ aggregation in brains with Alzheimer's disease (AD), while apolipoprotein-E (ApoE) in microglia mediates Aβ clearance. We studied the protease responsible for ApoE(4) degradation in human peripheral monocyte extracts, which are from the same lineage as microglia. We detected the hydrolytic activity for ApoE(4) in high-salt extracts with 2 M NaCl and found that the activity was inhibited by a serine protease inhibitor and an elastase-specific inhibitor, but not by other protease inhibitors. The extracts exhibited higher activity for the elastase substrate, and we followed the activity with ion-exchange and gel-filtration chromatography. Through silver staining, we partially purified a protein of 28 kDa, which was clarified as elastase by liquid chromatography-tandem mass spectrometry. These observations suggest that elastase is the key protease for ApoE(4) degradation. We also detected ApoE(4) hydrolytic activity in high-salt extracts in mouse microglial (BV-2) cell lysates, and showed that the ApoE(4) fragments by the BV-2 extracts differed from the fragments by the monocyte extracts. Though the ApoE(4) degradation by the extracts was not inhibited with elastase-specific inhibitors, it was inhibited by an elastase-specific monoclonal antibody, suggesting that elastase-like proteases in microglia differ from those of monocytes. Immunohistochemistry revealed that both elastase and ApoE were expressed in the senile plaques of brains with AD. In vitro studies also disclosed the localization of elastase in the microglial cell line, BV-2. Our results suggest that elastase-like proteases in the microglial cells surrounding Aβ plaques are responsible for ApoE degradation in the brain.

  5. Structural and biochemical studies on Vibrio cholerae Hsp31 reveals a novel dimeric form and Glutathione-independent Glyoxalase activity

    PubMed Central

    Dey, Sanjay

    2017-01-01

    Vibrio cholerae experiences a highly hostile environment at human intestine which triggers the induction of various heat shock genes. The hchA gene product of V. cholerae O395, referred to a hypothetical intracellular protease/amidase VcHsp31, is one such stress-inducible homodimeric protein. Our current study demonstrates that VcHsp31 is endowed with molecular chaperone, amidopeptidase and robust methylglyoxalase activities. Through site directed mutagenesis coupled with biochemical assays on VcHsp31, we have confirmed the role of residues in the vicinity of the active site towards amidopeptidase and methylglyoxalase activities. VcHsp31 suppresses the aggregation of insulin in vitro in a dose dependent manner. Through crystal structures of VcHsp31 and its mutants, grown at various temperatures, we demonstrate that VcHsp31 acquires two (Type-I and Type-II) dimeric forms. Type-I dimer is similar to EcHsp31 where two VcHsp31 monomers associate in eclipsed manner through several intersubunit hydrogen bonds involving their P-domains. Type-II dimer is a novel dimeric organization, where some of the intersubunit hydrogen bonds are abrogated and each monomer swings out in the opposite directions centering at their P-domains, like twisting of wet cloth. Normal mode analysis (NMA) of Type-I dimer shows similar movement of the individual monomers. Upon swinging, a dimeric surface of ~400Å2, mostly hydrophobic in nature, is uncovered which might bind partially unfolded protein substrates. We propose that, in solution, VcHsp31 remains as an equilibrium mixture of both the dimers. With increase in temperature, transformation to Type-II form having more exposed hydrophobic surface, occurs progressively accounting for the temperature dependent increase of chaperone activity of VcHsp31. PMID:28235098

  6. Apolipoprotein E, gender, and Alzheimer's disease: an overlooked, but potent and promising interaction.

    PubMed

    Ungar, Leo; Altmann, Andre; Greicius, Michael D

    2014-06-01

    Alzheimer's disease (AD) is an increasingly prevalent, fatal neurodegenerative disease that has proven resistant, thus far, to all attempts to prevent it, forestall it, or slow its progression. The ε4 allele of the Apolipoprotein E gene (APOE4) is a potent genetic risk factor for sporadic and late-onset familial AD. While the link between APOE4 and AD is strong, many expected effects, like increasing the risk of conversion from MCI to AD, have not been widely replicable. One critical, and commonly overlooked, feature of the APOE4 link to AD is that several lines of evidence suggest it is far more pronounced in women than in men. Here we review previous literature on the APOE4 by gender interaction with a particular focus on imaging-related studies.

  7. Longitudinal study of cerebrospinal fluid amyloid proteins and apolipoprotein E in patients with probable Alzheimer's disease.

    PubMed

    Pirttilä, T; Koivisto, K; Mehta, P D; Reinikainen, K; Kim, K S; Kilkku, O; Heinonen, E; Soininen, H; Riekkinen, P; Wisniewski, H M

    1998-06-12

    Levels of soluble amyloid beta protein (sAbeta), amyloid beta precursor protein (APP) and apolipoprotein E (apoE) were examined in cerebrospinal fluid (CSF) obtained twice, at baseline and after 3-year follow-up, from 25 patients with probable Alzheimer's disease (AD). Levels of sAbeta and apoE from patients with the apoE4 allele decreased with time, whereas the levels were similar in patients without apoE4 allele. Changes of sAbeta and apoE concentrations correlated significantly with those of mini-mental state examination (MMSE) scores. Levels of sAbeta did not change with time in patients with mild dementia, whereas they decreased significantly in patients with moderate dementia. ApoE concentrations decreased in both groups whereas APP levels were similar. We conclude that measurements of CSF sAbeta and apoE levels may be helpful in monitoring progression of the disease.

  8. Inflammation, cytokines, immune response, apolipoprotein E, cholesterol, and oxidative stress in Alzheimer disease: therapeutic implications.

    PubMed

    Candore, Giuseppina; Bulati, Matteo; Caruso, Calogero; Castiglia, Laura; Colonna-Romano, Giuseppina; Di Bona, Danilo; Duro, Giovanni; Lio, Domenico; Matranga, Domenica; Pellicanò, Mariavaleria; Rizzo, Claudia; Scapagnini, Giovanni; Vasto, Sonya

    2010-01-01

    Alzheimer disease (AD) is a heterogeneous and progressive neurodegenerative disease, which in Western society mainly accounts for senile dementia. Today many countries have rising aging populations and are facing an increased prevalence of age-related diseases, such as AD, with increasing health-care costs. Understanding the pathophysiology process of AD plays a prominent role in new strategies for extending the health of the elderly population. Considering the future epidemic of AD, prevention and treatment are important goals of ongoing research. However, a better understanding of AD pathophysiology must be accomplished to make this objective feasible. In this paper, we review some hot topics concerning AD pathophysiology that have an important impact on therapeutic perspectives. Hence, we have focused our attention on inflammation, cytokines, immune response, apolipoprotein E (APOE), cholesterol, oxidative stress, as well as exploring the related therapeutic possibilities, i.e., nonsteroidal antiinflammatory drugs, cytokine blocking antibodies, immunotherapy, diet, and curcumin.

  9. Apolipoprotein E alleles in Alzheimer`s and Parkinson`s patients

    SciTech Connect

    Poduslo, S.E.; Schwankhaus, J.D.

    1994-09-01

    A number of investigators have found an association between the apolipoprotein E4 allele and Alzheimer`s disease. The E4 allele appears at a higher frequency in late onset familial Alzheimer`s patients. In our studies we obtained blood samples from early and late onset familial and sporadic Alzheimer`s patients and spouses, as well as from Parkinson`s patients. The patients were diagnosed as probable Alzheimer`s patients after a neurological examination, extensive blood work, and a CAT scan. The diagnosis was made according to the NINCDS-ADRDA criteria. The apolipoprotein E4 polymorphism was detected after PCR amplification of genomic DNA, restriction enzyme digestion with Hhal, and polyacrylamide gel electrophoresis. Ethidium bromide-stained bands at 91 bp were designated as allele 3, at 83 bp as allele 2, and at 72 bp as allele 4. Of the 84 probable Alzheimer`s patients (all of whom were Caucasian), 47 were heterozygous and 13 were homozygous for the E4 allele. There were 26 early onset patients; 13 were heterozygous and 7 homozygous for the E4 allele. The frequencies for the E4 allele for late onset familial patients was 0.45 and for sporadic patients was 0.37. We analyzed 77 spouses with an average age of 71.9 {plus_minus} 7.4 years as controls, and 15 were heterozygous for the E4 allele for an E4 frequency of 0.097. Of the 53 Parkinson`s patients, 11 had the E4 allele for a frequency of 0.113. Thus our findings support the association of the ApoE4 allele with Alzheimer`s disease.

  10. Amphiphile dependency of the monomeric and dimeric forms of acetylcholinesterase from human erythrocyte membrane.

    PubMed

    Ott, P; Brodbeck, U

    1984-08-08

    Human erythrocyte membrane-bound acetylcholinesterase was converted to a monomeric species by treatment of ghosts with 2-mercaptoethanol and iodoacetic acid. After solubilization with Triton X-100, the reduced and alkylated enzyme was partially purified by affinity chromatography and separated from residual dimeric enzyme by sucrose density gradient centrifugation in a zonal rotor. Monomeric and dimeric acetylcholinesterase showed full enzymatic activity in presence of Triton X-100 whereas in the absence of detergent, activity was decreased to approx. 20% and 15%, respectively. Preformed egg phosphatidylcholine vesicles fully sustained activity of the monomeric species whereas the dimer was only 80% active. The results suggest that a dimeric structure is not required for manifestation of amphiphile dependency of membrane-bound acetylcholinesterase from human erythrocytes. Furthermore, monomeric enzyme appears to be more easily inserted into phospholipid bilayers than the dimeric species.

  11. Recombinant neural protein PrP can bind with both recombinant and native apolipoprotein E in vitro.

    PubMed

    Gao, Chen; Lei, Yan-Jun; Han, Jun; Shi, Qi; Chen, Lan; Guo, Yan; Gao, Yong-Jun; Chen, Jian-Ming; Jiang, Hui-Ying; Zhou, Wei; Dong, Xiao-Ping

    2006-09-01

    The most essential and crucial step during the pathogenesis of transmissible spongiform encephalopathy is the conformational change of cellular prion protein (PrP(C)) to pathologic isoform (PrP(Sc)). A lot of data revealed that caveolae-like domains (CLDs) in the cell surface were the probable place where the conversion of PrP proteins happened. Apolipoprotein E (ApoE) is an apolipoprotein which is considered to play an important role in the development of Alzheimer's disease and other neurodegenerative diseases by forming protein complex through binding to the receptor located in the clathrin-coated pits of the cell surface. In this study, a 914-bp cDNA sequence encoding human ApoE3 was amplified from neuroblastoma cell line SH-SY5Y. Three human ApoE isomers were expressed and purified from Escherichia coli. ApoE-specific antiserum was prepared by immunizing rabbits with the purified ApoE3. GST/His pull-down assay, immunoprecipitation and ELISA revealed that three full-length ApoE isomers interact with the recombinant full-length PrP protein in vitro. The regions corresponding to protein binding were mapped in the N-terminal segment of ApoE (amino acid 1-194) and the N-terminal of PrP (amino acid 23-90). Moreover, the recombinant PrP showed the ability to form a complex with the native ApoE from liver tissues. Our data provided direct evidence of molecular interaction between ApoE and PrP. It also supplied scientific clues for assessing the significance of CLDs on the surface of cellular membrane in the process of conformational conversion from PrP(C) to PrP(Sc) and probing into the pathogenesis of transmissible spongiform encephalopathy.

  12. Scavenger receptor function of mouse Fcγ receptor III contributes to progression of atherosclerosis in apolipoprotein E hyperlipidemic mice.

    PubMed

    Zhu, Xinmei; Ng, Hang Pong; Lai, Yen-Chun; Craigo, Jodi K; Nagilla, Pruthvi S; Raghani, Pooja; Nagarajan, Shanmugam

    2014-09-01

    Recent studies showed loss of CD36 or scavenger receptor-AI/II (SR-A) does not ameliorate atherosclerosis in a hyperlipidemic mouse model, suggesting receptors other than CD36 and SR-A may also contribute to atherosclerosis. In this report, we show that apolipoprotein E (apoE)-CD16 double knockout (DKO; apoE-CD16 DKO) mice have reduced atherosclerotic lesions compared with apoE knockout mice. In vivo and in vitro foam cell analyses showed apoE-CD16 DKO macrophages accumulated less neutral lipids. Reduced foam cell formation in apoE-CD16 DKO mice is not due to change in expression of CD36, SR-A, and LOX-1. This led to a hypothesis that CD16 may have scavenger receptor activity. We presented evidence that a soluble form of recombinant mouse CD16 (sCD16) bound to malondialdehyde-modified low-density lipoprotein (MDALDL), and this binding is blocked by molar excess of MDA- modified BSA and anti-MDA mAbs, suggesting CD16 specifically recognizes MDA epitopes. Interestingly, sCD16 inhibited MDALDL binding to macrophage cell line, as well as soluble forms of recombinant mouse CD36, SR-A, and LOX-1, indicating CD16 can cross-block MDALDL binding to other scavenger receptors. Anti-CD16 mAb inhibited immune complex binding to sCD16, whereas it partially inhibited MDALDL binding to sCD16, suggesting MDALDL binding site may be in close proximity to the immune complex binding site in CD16. Loss of CD16 expression resulted in reduced levels of MDALDL-induced proinflammatory cytokine expression. Finally, CD16-deficient macrophages showed reduced MDALDL-induced Syk phosphorylation. Collectively, our findings suggest scavenger receptor activity of CD16 may, in part, contribute to the progression of atherosclerosis.

  13. Evidence for major gene inheritance of Alzheimer disease in families of patients with and without Apolipoprotein E {epsilon}4

    SciTech Connect

    Rao, V.S.; Auerbach, S.A.; Farrer, L.A.

    1996-09-01

    Apolipoprotein E (APOE) genotype is the single most important determinant to the common form of Alzheimer disease (AD) yet identified. Several studies show that family history of AD is not entirely accounted for by APOE genotype. Also, there is evidence for an interaction between APOE genotype and gender. We carried out a complex segregation analysis in 636 nuclear families of consecutively ascertained and rigorously diagnosed probands in the Multi-Institutional Research in Alzheimer Genetic Epidemiology study in order to derive models of disease transmission which account for the influences of APOE genotype of the proband and gender. In the total group of families, models postulating sporadic occurrence, no major gene effect, random environmental transmission, and Mendelian inheritance were rejected. Transmission of AD in families of probands with at least one {epsilon}4 allele best fit a dominant model. Moreover, single gene inheritance best explained clustering of the disorder in families of probands lacking E4, but a more complex genetic model or multiple genetic models may ultimately account for risk in this group of families. Our results also suggest that susceptibility to AD differs between men and women regardless of the proband`s APOE status. Assuming a dominant model, AD appears to be completely penetrant in women, whereas only 62%-65% of men with predisposing genotypes develop AD. However, parameter estimates from the arbitrary major gene model suggests that AD is expressed dominantly in women and additively in men. These observations, taken together with epidemiologic data, are consistent with the hypothesis of an interaction between genes and other biological factors affecting disease susceptibility. 76 refs., 4 tabs.

  14. Bowman-Birk protease inhibitor from the seeds of Vigna unguiculata forms a highly stable dimeric structure.

    PubMed

    Rao, K N; Suresh, C G

    2007-10-01

    Different protease inhibitors including Bowman-Birk type (BBI) have been reported from the seeds of Vigna unguiculata. Protease isoinhibitors of double-headed Bowman-Birk type from the seeds of Vigna unguiculata have been purified and characterized. The BBI from Vigna unguiculata (Vu-BBI) has been found to undergo self-association to form very stable dimers and more complex oligomers, by size-exclusion chromatography and SDS-PAGE in the presence of urea. Many BBIs have been reported to undergo self-association to form homodimers or more complex oligomers in solution. Only one dimeric crystal structure of a BBI (pea-BBI) is reported to date. We report the three-dimensional structure of a Vu-BBI determined at 2.5 A resolution. Although, the inhibitor has a monomer fold similar to that found in other known structures of Bowman-Birk protease inhibitors, its quaternary structure is different from that commonly observed in this family. The structural elements responsible for the stability of monomer molecule and dimeric association are discussed. The Vu-BBI may use dimeric or higher quaternary association to maintain the physiological state and to execute its biological function.

  15. The apolipoprotein E/CI/CII gene cluster and late-onset Alzheimer disease

    SciTech Connect

    Yu, Chang-En; Nemens, E.; Olson, J.M.; Goddard, K.A.B.; Kukull, W.A.; Payami, H.; Boehnke, M.; Wijsman, E.M.; Orr, H.T.; White, J.A.

    1994-04-01

    The chromosome 19 apolipoprotein E/CI/CII gene cluster was examined for evidence of linkage to a familial Alzheimer disease (FAD) locus. The family groups studied were Volga German (VG), early-onset non-VG (ENVG; mean age at onset <60 years), and late-onset families. A genetic association was observed between apolipoprotein E (ApoE) allele E4 and FAD in late-onset families; the E4 allele frequency was .51 in affected subjects, .37 in at-risk subjects, .11 in spouses, and .19 in unrelated controls. The differences between the E4 frequencies in affected subjects versus controls and in at-risk subjects versus controls were highly significant. No association between the E4 allele and FAD was observed in the ENVG or VG groups. A statistically significant allelic association between E4 and AD was also observed in a group of unrelated subjects; the E4 frequency was .26 in affected subjects, versus .19 in controls (Z[sub SND] = 2.20, P < .03). Evidence of linkage of ApoE and ApoCII to FAD was examined by maximum-likelihood methods, using three models and assuming autosomal dominant inheritance: (1) age-dependent penetrance, (2) extremely low (1%) penetrance, and (3) age-dependent penetrance corrected for sporadic Alzheimer disease (AD). For ApoCII in late-onset families, results for close linkage were negative, and only small positive lod-score-statistic (Z) values were obtained. For ApoE in late-onset kindreds, positive Z values were obtained when either allele frequencies from controls or allele frequencies from the families were used. When linkage disequilibrium was incorporated into the analysis, the Z values increased. For the ENVG group, results for ApoE and ApoCII were uniformly negative. Affected-pedigree-member analysis gave significant results for the late-onset kindreds, for ApoE, when control allele frequencies were used but not when allele frequencies were derived from the families. 58 refs., 6 tabs.

  16. The Apolipoprotein E/CI/CII Gene Cluster and Late-Onset Alzheimer Disease

    PubMed Central

    Yu, Chang-En; Payami, Haydeh; Olson, Jane M.; Boehnke, Michael; Wijsman, Ellen M.; Orr, Harry T.; Kukull, Walter A.; Goddard, Katrina A. B.; Nemens, Ellen; White, June A.; Alonso, M. Elisa; Taylor, Todd D.; Ball, Melvyn J.; Kaye, Jeffrey; Morris, John; Chui, Helena; Sadovnick, Adele D.; Martin, George M.; Larson, Eric B.; Heston, Leonard L.; Bird, Thomas D.; Schellenberg, Gerard D.

    1994-01-01

    The chromosome 19 apolipoprotein E/CI/CII gene cluster was examined for evidence of linkage to a familial Alzheimer disease (FAD) locus. The family groups studied were Volga German (VG), early-onset non-VG (ENVG; mean age at onset <60 years), and late-onset families. A genetic association was observed between apolipoprotein E (ApoE) allele ε4 and FAD in late-onset families; the ε4 allele frequency was .51 in affected subjects, .37 in at-risk subjects, .11 in spouses, and .19 in unrelated controls. The differences between the ε4 frequencies in affected subjects versus controls and in at-risk subjects versus controls were highly significant (standard normal deviate [ZSND]) = 7.37, P < 10−9; and ZSND = 4.07, P < .00005, respectively). No association between the ε4 allele and FAD was observed in the ENVG or VG groups. A statistically significant allelic association between ε4 and AD was also observed in a group of unrelated subjects; the ε4 frequency was .26 in affected subjects, versus .19 in controls (ZSND = 2.20, P < .03). Evidence of linkage of ApoE and ApoCII to FAD was examined by maximum-likelihood methods, using three models and assuming autosomal dominant inheritance: (1) age-dependent penetrance, (2) extremely low (1%) penetrance, and (3) age-dependent penetrance corrected for sporadic Alzheimer disease (AD). For ApoCII in late-onset families, results for close linkage were negative, and only small positive lod-score-statistic (Z) values were obtained (model 1, maximum Z [Zmax] = 0.61, recombination fraction [θ] = .30; model 2, Zmax = 0.47, θ = .20). For ApoE in late-onset kindreds, positive Z values were obtained when either allele frequencies from controls (model 1, Zmax = 2.02, θ = .15; model 2, Zmax = 3.42, θ = .05) or allele frequencies from the families (model 1, Zmax = 1.43, θ = .15; model 2, Zmax = 1.70, θ = .05) were used. When linkage disequilibrium was incorporated into the analysis, the Z values increased (model 1, Zmax = 3.17,

  17. The dimers of cyanamide

    NASA Astrophysics Data System (ADS)

    Moffat, J. B.

    Ab initio calculations have been performed on various dimeric forms of cyanamide. The "nondissociative" dimerization of cyanamide leads to cyclic molecules all of which are unstable with respect to cyanamide. However, the molecules produced by "dissociative" dimerization are stable relative to cyanamide. Dicyandiamide is found to be the most stable of nine dimeric configurations.

  18. Apolipoprotein E-Mimetic COG1410 Reduces Acute Vasogenic Edema following Traumatic Brain Injury

    PubMed Central

    Cao, Fang; Wu, Yue; Zhong, Jianjun; Liu, Jieshi; Qin, Xinghu; Chen, Ligang; Vitek, Michael P.; Li, Fengqiao; Xu, Lu

    2016-01-01

    Abstract The degree of post-traumatic brain edema and dysfunction of the blood–brain barrier (BBB) influences the neurofunctional outcome after a traumatic brain injury (TBI). Previous studies have demonstrated that the administration of apolipoprotein E-mimetic peptide COG1410 reduces the brain water content after subarachnoid hemorrhage, intra-cerebral hemorrhage, and focal brain ischemia. However, the effects of COG1410 on vasogenic edema following TBI are not known. The current study evaluated the effects of 1 mg/kg daily COG1410 versus saline administered intravenously after a controlled cortical impact (CCI) injury on BBB dysfunction and vasogenic edema at an acute stage in mice. The results demonstrated that treatment with COG1410 suppressed the activity of matrix metalloproteinase-9, reduced the disruption of the BBB and Evans Blue dye extravasation, reduced the TBI lesion volume and vasogenic edema, and decreased the functional deficits compared with mice treated with vehicle, at an acute stage after CCI. These findings suggest that COG1410 is a promising preclinical therapeutic agent for the treatment of traumatic brain injury. PMID:26192010

  19. Apolipoprotein E4 and Insulin Resistance Interact to Impair Cognition and Alter the Epigenome and Metabolome

    PubMed Central

    Johnson, Lance A.; Torres, Eileen Ruth S.; Impey, Soren; Stevens, Jan F.; Raber, Jacob

    2017-01-01

    Apolipoprotein E4 (E4) and type 2 diabetes are major risk factors for cognitive decline and late onset Alzheimer’s disease (AD). E4-associated phenotypes and insulin resistance (IR) share several features and appear to interact in driving cognitive dysfunction. However, shared mechanisms that could explain their overlapping pathophysiology have yet to be found. We hypothesized that, compared to E3 mice, E4 mice would be more susceptible to the harmful cognitive effects of high fat diet (HFD)-induced IR due to apoE isoform-specific differences in brain metabolism. While both E3 and E4 mice fed HFD displayed impairments in peripheral metabolism and cognition, deficits in hippocampal-dependent spatial learning and memory were exaggerated in E4 mice. Combining genome-wide measures of DNA hydroxymethylation with comprehensive untargeted metabolomics, we identified novel alterations in purine metabolism, glutamate metabolism, and the pentose phosphate pathway. Finally, in E4 mice, the metabolic and cognitive deficiencies caused by HFD were rescued by switching to a low fat diet for one month, suggesting a functional role was associated with reversal of the same metabolic pathways described above. These results suggest a susceptibility of E4 carriers to metabolic impairments brought on by IR, and may guide development of novel therapies for cognitive decline and dementia. PMID:28272510

  20. Intracellular trafficking of recycling apolipoprotein E in Chinese hamster ovary cells.

    PubMed

    Braun, Nicole A; Mohler, Peter J; Weisgraber, Karl H; Hasty, Alyssa H; Linton, MacRae F; Yancey, Patricia G; Su, Yan Ru; Fazio, Sergio; Swift, Larry L

    2006-06-01

    We have investigated apolipoprotein E (apoE) recycling in Chinese hamster ovary (CHO) cells, a peripheral cell that does not produce lipoproteins or express apoE. Using a pulse-chase protocol in which cells were pulsed with 125I-apoE-VLDL and chased for different periods, approximately 30% of the apoE internalized during the pulse was resecreted within a 4 h chase in a relatively lipid-free state. The addition of lysosomotropic agents or brefeldin A had no effect on apoE recycling. Unlike previous results with hepatocytes and macrophages, neither apoA-I nor upregulation of ABCA1 stimulated apoE recycling. However, cyclodextrin, which extracts cholesterol from plasma membrane lipid rafts, increased recycling. Confocal studies revealed that apoE, internalized during a 1 h pulse, colocalizes with early endosomal antigen-1, Rab5, Rab11a, and lysobisphosphatidic acid but not with lysosomal-associated membrane protein-1. Colocalization of apoE and Rab11a persisted even after cells had been chased for 1 h, suggesting a pool of apoE within the endosomal recycling compartment (ERC). Our data suggest that apoE recycling in CHO cells is linked to cellular cholesterol removal via the ERC and phospholipid-containing acceptors in a pathway alternative to the ABCA1-apoA-I axis.

  1. Apolipoprotein E4 as a predictor of outcomes in pediatric mild traumatic brain injury.

    PubMed

    Moran, Lisa M; Taylor, H Gerry; Ganesalingam, Kalaichelvi; Gastier-Foster, Julie M; Frick, Jessica; Bangert, Barbara; Dietrich, Ann; Nuss, Kathryn E; Rusin, Jerome; Wright, Martha; Yeates, Keith O

    2009-09-01

    The epsilon4 allele of the apolipoprotein E (APOE) gene has been linked to negative outcomes among adults with traumatic brain injury (TBI) across the spectrum of severity, with preliminary evidence suggesting a similar pattern among children. This study investigated the relationship of the APOE epsilon4 allele to outcomes in children with mild TBI. Participants in this prospective, longitudinal study included 99 children with mild TBI between the ages of 8 and 15 recruited from consecutive admissions to Emergency Departments at two large children's hospitals. Outcomes were assessed acutely in the Emergency Department and at follow-ups at 2 weeks, 3 months, and 12 months post-injury. Among the 99 participants, 28 had at least one epsilon4 allele. Children with and without an epsilon4 allele did not differ demographically. Children with an epsilon4 allele were significantly more likely than those without an epsilon4 allele to have a Glasgow Coma Scale score of less than 15, but the groups did not differ on any other measures of injury severity. Those with an epsilon4 allele exhibited better performance than children without an epsilon4 allele on a test of constructional skill, but the groups did not differ on any other neuropsychological tests. Children with and without an epsilon4 allele also did not differ on measures of post-concussive symptoms. Overall, the findings suggest that the APOE epsilon4 allele is not consistently related to the outcomes of mild TBI in children.

  2. Apolipoprotein E (APOE) ϵ4 Allele Is Associated with Increased Symptom Reporting Following Sports Concussion.

    PubMed

    Merritt, Victoria C; Arnett, Peter A

    2016-01-01

    Exploring the relationship between genetic factors and outcome following brain injury has received increased attention in recent years. However, few studies have evaluated the influence of genes on specific sequelae of concussion. The purpose of this study was to determine how the ϵ4 allele of the apolipoprotein E (APOE) gene influences symptom expression following sports-related concussion. Participants included 42 collegiate athletes who underwent neuropsychological testing, including completion of the Post-Concussion Symptom Scale (PCSS), within 3 months after sustaining a concussion (73.8% were evaluated within 1 week). Athletes provided buccal samples that were analyzed to determine the make-up of their APOE genotype. Dependent variables included a total symptom score and four symptom clusters derived from the PCSS. Mann-Whitney U tests showed higher scores reported by athletes with the ϵ4 allele compared to those without it on the total symptom score and the physical and cognitive symptom clusters. Furthermore, logistic regression showed that the ϵ4 allele independently predicted those athletes who reported physical and cognitive symptoms following concussion. These findings illustrate that ϵ4+ athletes report greater symptomatology post-concussion than ϵ4- athletes, suggesting that the ϵ4 genotype may confer risk for poorer post-concussion outcome. (JINS, 2016, 22, 89-94).

  3. Extracellular Proteolysis of Apolipoprotein E (apoE) by Secreted Serine Neuronal Protease

    PubMed Central

    Tamboli, Irfan Y.; Heo, Dongeun; Rebeck, G. William

    2014-01-01

    Under normal conditions, brain apolipoprotein E (apoE) is secreted and lipidated by astrocytes, then taken up by neurons via receptor mediated endocytosis. Free apoE is either degraded in intraneuronal lysosomal compartments or released. Here we identified a novel way by which apoE undergoes proteolysis in the extracellular space via a secreted neuronal protease. We show that apoE is cleaved in neuronal conditioned media by a secreted serine protease. This apoE cleavage was inhibited by PMSF and α1-antichymotrypsin, but not neuroserpin-1 or inhibitors of thrombin and cathepsin G, supporting its identity as a chymotrypsin like protease. In addition, apoE incubation with purified chymotrypsin produced a similar pattern of apoE fragments. Analysis of apoE fragments by mass spectrometry showed cleavages occuring at the C-terminal side of apoE tryptophan residues, further supporting our identification of cleavage by chymotrypsin like protease. Hippocampal neurons were more efficient in mediating this apoE cleavage than cortical neurons. Proteolysis of apoE4 generated higher levels of low molecular weight fragments compared to apoE3. Primary glial cultures released an inhibitor of this proteolytic activity. Together, these studies reveal novel mechanism by which apoE can be regulated and therefore could be useful in designing apoE directed AD therapeutic approaches. PMID:24675880

  4. Color multiplexing hybridization probes using the apolipoprotein E locus as a model system for genotyping.

    PubMed

    Bernard, P S; Pritham, G H; Wittwer, C T

    1999-09-10

    Fluorescent hybridization probes were multiplexed for color genotyping of the apolipoprotein E locus using model oligonucleotide targets. Fluorescence resonance energy transfer was observed during adjacent hybridization of 3'-fluorescein-labeled "donor" probes paired with 5'-labeled "acceptor" probes with different emission spectra reporting at codons 112 and 158. The acceptor dyes emitted at either 640 nm (LightCycler Red 640) or 705 nm (LightCycler Red 705) and were monitored with a LightCycler, a thermal cycler with an integrated fluorimeter. The color of the acceptor dye identified each site and the characteristic melting temperatures of the fluorescein-labeled probes identified single base changes within each codon. Color compensation of temperature-dependent spectral overlap was applied to completely separate each channel. Competition between the probes and the complementary strand for the target sequence decreased resonance energy transfer, indicating an advantage of single-stranded target. Hybridization probes of the same length, but different GC content are T(m) shifted by the same amount during A:C mismatch duplex melting. Genotyping was optimal at both sites if melting curve analysis was preceded by a slow (1 degrees C/s) annealing phase. Although each site preferred different concentrations of Mg(2+) and target strand for optimal genotyping, conditions for multiplexing were found. This method, along with an appropriate amplification technique, should allow real-time multiplex genotyping from genomic DNA.

  5. Apolipoprotein E polymorphism in alagille syndrome and progressive familial intrahepatic cholestasis.

    PubMed

    Socha, P; Nowicka, G; Jankowska, I; Rujner, J; Pawłowska, J; Socha, J

    2000-04-01

    The aim of the study was to assess the apolipoprotein E polymorphism (apoE) in two familial cholestatic diseases-Alagille syndrome (AS) and progressive familial intrahepatic cholestasis (PFIC)-and to estimate its association with gallstone formation, cholesterol levels, and response to UDCA treatment. We investigated 16 children with AS age 8.8 +/- 5.7 years (mean +/- SD) and 18 children with PFIC age 6.3 +/- 4.6 years. The frequency of the epsilon-2 allele in AS and PFIC was higher and the frequency of the epsilon-3 allele was lower than in controls. Gallstones were diagnosed in nine children with PFIC and different apoE phenotypes. No association between phenotype and cholesterol levels or response to UDCA therapy was observed in the patients studied. In conclusion, the allele epsilon-2 is overrepresented in AS and PFIC, similar to primary biliary cirrhosis, although this does not seem to contribute to different cholesterol levels, gallstones, and response to UDCA therapy.

  6. Allergic lung inflammation promotes atherosclerosis in apolipoprotein E-deficient mice.

    PubMed

    Liu, Cong-Lin; Wang, Yi; Liao, Mengyang; Santos, Marcela M; Fernandes, Cleverson; Sukhova, Galina K; Zhang, Jin-Ying; Cheng, Xiang; Yang, Chongzhe; Huang, Xiaozhu; Levy, Bruce; Libby, Peter; Wu, Gongxiong; Shi, Guo-Ping

    2016-05-01

    Inflammation drives asthma and atherosclerosis. Clinical studies suggest that asthmatic patients have a high risk of atherosclerosis. Yet this hypothesis remains uncertain, given that Th2 imbalance causes asthma whereas Th1 immunity promotes atherosclerosis. In this study, chronic allergic lung inflammation (ALI) was induced in mice by ovalbumin sensitization and challenge. Acute ALI was induced in mice by ovalbumin and aluminum sensitization and ovalbumin challenge. Atherosclerosis was produced in apolipoprotein E-deficient (Apoe(-/-)) mice with a Western diet. When chronic ALI and atherosclerosis were produced simultaneously, ALI increased atherosclerotic lesion size, lesion inflammatory cell content, elastin fragmentation, smooth muscle cell (SMC) loss, lesion cell proliferation, and apoptosis. Production of acute ALI before atherogenesis did not affect lesion size, but increased atherosclerotic lesion CD4(+) T cells, lesion SMC loss, angiogenesis, and apoptosis. Production of acute ALI after atherogenesis also did not change atherosclerotic lesion area, but increased lesion elastin fragmentation, cell proliferation, and apoptosis. In mice with chronic ALI and diet-induced atherosclerosis, daily inhalation of a mast cell inhibitor or corticosteroid significantly reduced atherosclerotic lesion T-cell and mast cell contents, SMC loss, angiogenesis, and cell proliferation and apoptosis, although these drugs did not affect lesion area, compared with those that received vehicle treatment. In conclusion, both chronic and acute ALI promote atherogenesis or aortic lesion pathology, regardless whether ALI occurred before, after, or at the same time as atherogenesis. Antiasthmatic medication can efficiently mitigate atherosclerotic lesion pathology.

  7. The Complex Role of Apolipoprotein E in Alzheimer's Disease: an Overview and Update.

    PubMed

    Mahoney-Sanchez, Laura; Belaidi, Abdel Ali; Bush, Ashley I; Ayton, Scott

    2016-11-01

    Apolipoprotein E (ApoE) plays a crucial role in the homeostatic control of lipids in both the periphery and the central nervous system (CNS). In humans, ApoE exists in three different isoforms: ε2, ε3 and ε4. ApoE ε3 is the most common isoform, while the ε4 isoform confers the greatest genetic risk for Alzheimer's disease (AD). However, the mechanisms underlying how ApoE contributes to the pathogenesis of AD are still debated. ApoE has been shown to impact amyloid β (Aβ) deposition and clearance in the brain. ApoE also has Aβ-independent pathways in AD, which has led to the discovery of new roles of ApoE ranging from mitochondria dysfunction to, most recently, iron metabolism. Here, we review the role of ApoE in health and in AD, with the view of identifying therapeutic approaches that could prevent the risk associated with the ε4 isoform.

  8. Expression of the human apolipoprotein E gene suppresses steroidogenesis in mouse Y1 adrenal cells

    SciTech Connect

    Reyland, M.E.; Forgez, P.; Prack, M.M.; Williams, D.L. ); Gwynne, J.T. )

    1991-03-15

    The lipid transport protein, apolipoprotein E (apoE), is expressed in many peripheral tissues in vivo including the adrenal gland and testes. To investigate the role of apoE in adrenal cholesterol homeostasis, the authors have expressed a human apoE genomic clone in the Y1 mouse adrenocortical cell line. Y1 cells do not express endogenous apoE mRNA or protein. Expression of apoE in Y1 cells resulted in a dramatic decrease in basal steroidogenesis; secretion of fluorogenic steroid was reduced 7- to {gt}100-fold relative to Y1 parent cells. Addition of 5-cholesten-3{beta},25-idol failed to overcome the suppression of steroidogenesis in these cells. Cholesterol esterification under basal conditions, as measured by the production of cholesteryl ({sup 14}C)oleate, was similar in the Y1 parent and the apoE-transfected cell lines. Upon incubation with adrenocorticotropin or dibutyryl cAMP, production of cholesteryl ({sup 14}C)oleate decreased 5-fold in the Y1 parent cells but was unchanged in the apoE-transfected cell lines. These results suggest that apoE may be an important modulator of cholesterol utilization and steroidogenesis in adrenal cells.

  9. Coronary artery disease and plasma apolipoprotein E4 in mild cognitive impairment

    PubMed Central

    Barekatain, Majid; Zahedian, Faezeh; Askarpour, Hedyeh; Maracy, Mohammad Reza; Hashemi-Jazi, Mohammad; Aghaye-Ghazvini, Mohammad Reza

    2014-01-01

    BACKGROUND Atherosclerosis and apolipoprotein E4 (APOE4) are known risks for Dementia. We sought to evaluate the relationship between coronary atherosclerosis and APOE4 with mild cognitive impairment (MCI). METHODS In a case-control study, subjects with age more than 60 years and recent coronary angiography were evaluated by mini-mental state examination and neuropsychiatry unit cognitive assessment tool (NUCOG) to find the patients with MCI (n = 40) and the controls with normal cognition (n = 40). Coronary angiography records were re-assessed to find the severity of coronary artery disease by the Gensini scores. Plasma levels of APOE4 were measured. RESULTS There were no-significant difference between the 2 groups regarding the plasma APOE4 levels (P = 0.706) and the Gensini scores (P = 0.236). Associations between the Gensini scores and the NUCOG scores in the MCI group (r = −0.196, P = 0.225) and the control group (r = 0.189, P = 0.243) were not significant. However, the interaction effect between the Gensini and the NUCOG scores based on allocation to the control or the patient groups showed statistically significant difference (F(1,67) = 4.84, P = 0.031). CONCLUSION Although atherosclerosis has been considered as known risk factor for dementia and MCI, this study could not reveal that coronary atherosclerosis-related to declining in cognitive functioning. There was no significant association between plasma APOE4 levels and MCI. PMID:25477981

  10. C-terminal interactions of apolipoprotein E4 respond to the postprandial state.

    PubMed

    Tetali, Sarada D; Budamagunta, Madhu S; Voss, John C; Rutledge, John C

    2006-07-01

    Increased triglyceride-rich lipoproteins (TGRLs) in the postprandial state are associated with atherosclerosis. We investigated whether the postprandial state induced structural changes at the apolipoprotein E4 (apoE4) C terminus, its principal lipid binding domain, using electron paramagnetic resonance (EPR) spectroscopy of a site-directed spin label attached to the cysteine of apoE4-W264C. Spin coupling between labels located in the C termini was followed after mixing with preprandial and postprandial human plasma samples. Our results indicate that postprandial plasma triggers a reorganization of the protein such that the dipolar broadening is diminished, indicating a reduction in C-terminal interaction. The loss of spectral broadening was directly correlated with an increase in postprandial plasma triglycerides and was reduced with delipidated plasma. The spin-labeled apoE4 displayed a lipid preference of VLDL > LDL > HDL in the preprandial and postprandial states. The apoE4 shift to VLDL during the postprandial state was accompanied by a loss in spectral broadening of the protein. These findings suggest that apoE4 associated with LDL maintains self-association via its C terminus and that this association is diminished in VLDL-associated protein. Lipolyzed TGRL reflected a depletion of the C-terminal interaction of apoE4. Addition of palmitate to VLDL gave a similar response as lipolyzed TGRL, suggesting that lipolysis products play a major role in reorganizing apoE4 during the postprandial state.

  11. Longitudinal Trajectories of Cholesterol from Midlife through Late Life according to Apolipoprotein E Allele Status

    PubMed Central

    Downer, Brian; Estus, Steven; Katsumata, Yuriko; Fardo, David W.

    2014-01-01

    Background: Previous research indicates that total cholesterol levels increase with age during young adulthood and middle age and decline with age later in life. This is attributed to changes in diet, body composition, medication use, physical activity, and hormone levels. In the current study we utilized data from the Framingham Heart Study Original Cohort to determine if variations in apolipoprotein E (APOE), a gene involved in regulating cholesterol homeostasis, influence trajectories of total cholesterol, HDL cholesterol, and total: HDL cholesterol ratio from midlife through late life. Methods: Cholesterol trajectories from midlife through late life were modeled using generalized additive mixed models and mixed-effects regression models. Results: APOE e2+ subjects had lower total cholesterol levels, higher HDL cholesterol levels, and lower total: HDL cholesterol ratios from midlife to late life compared to APOE e3 and APOE e4+ subjects. Statistically significant differences in life span cholesterol trajectories according to gender and use of cholesterol-lowering medications were also detected. Conclusion: The findings from this research provide evidence that variations in APOE modify trajectories of serum cholesterol from midlife to late life. In order to efficiently modify cholesterol through the life span, it is important to take into account APOE allele status. PMID:25325355

  12. Expression of apolipoprotein E by cultured vascular smooth muscle cells is controlled by growth state

    PubMed Central

    1988-01-01

    Rat vascular smooth muscle cells (SMC) in culture synthesize and secrete a approximately 38,000-Mr protein doublet or triplet that, as previously described (Majack and Bornstein. 1984. J. Cell Biol. 99:1688- 1695), rapidly and reversibly accumulates in the SMC culture medium upon addition of heparin. In the present study, we show that this approximately 38,000-Mr heparin-regulated protein is electrophoretically and immunologically identical to apolipoprotein E (apo-E), a major plasma apolipoprotein involved in cholesterol transport. In addition, we show that expression of apo-E by cultured SMC varies according to growth state: while proliferating SMC produced little apo-E and expressed low levels of apo-E mRNA, quiescent SMC produced significantly more apo-E (relative to other proteins) and expressed markedly increased levels of apo-E mRNA. Northern analysis of RNA extracted from aortic tissue revealed that fully differentiated, quiescent SMC contain significant quantities of apo-E mRNA. These data establish aortic SMC as a vascular source for apo-E and suggest new functional roles for this apolipoprotein, possibly unrelated to traditional concepts of lipid metabolism. PMID:2458361

  13. Osteopontin deficiency reduces kidney damage from hypercholesterolemia in Apolipoprotein E-deficient mice

    PubMed Central

    Pei, Zouwei; Okura, Takafumi; Nagao, Tomoaki; Enomoto, Daijiro; Kukida, Masayoshi; Tanino, Akiko; Miyoshi, Ken-ichi; Kurata, Mie; Higaki, Jitsuo

    2016-01-01

    Hypercholesterolemia is a well-established risk factor for kidney injury, which can lead to chronic kidney disease (CKD). Osteopontin (OPN) has been implicated in the pathology of several renal conditions. This study was to evaluate the effects of OPN on hypercholesterolemia induced renal dysfunction. Eight-week-old male mice were divided into 4 groups: apolipoprotein E knockout (ApoE−/−) and ApoE/OPN knockout (ApoE−/−/OPN−/−) mice fed a normal diet (ND) or high cholesterol diet (HD). After 4 weeks, Periodic acid-Schiff (PAS) and oil red O staining revealed excessive lipid deposition in the glomeruli of ApoE−/−HD mice, however, significantly suppressed in ApoE−/−/OPN−/−HD mice. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression was lower in the glomeruli of ApoE−/−/OPN−/−HD mice than ApoE−/−HD mice. In vitro study, primary mesangial cells were incubated with recombinant mouse OPN (rmOPN). RmOPN induced LOX-1 mRNA and protein expression in primary mesangial cells. Pre-treatment with an ERK inhibitor suppressed the LOX-1 gene expression induced by rmOPN. These results indicate that OPN contributes to kidney damage in hypercholesterolemia and suggest that inhibition of OPN may provide a potential therapeutic target for the prevention of hypercholesterolemia. PMID:27353458

  14. Differential regulation of amyloid-β endocytic trafficking and lysosomal degradation by apolipoprotein E isoforms.

    PubMed

    Li, Jie; Kanekiyo, Takahisa; Shinohara, Mitsuru; Zhang, Yunwu; LaDu, Mary Jo; Xu, Huaxi; Bu, Guojun

    2012-12-28

    Aggregation of amyloid-β (Aβ) peptides leads to synaptic disruption and neurodegeneration in Alzheimer disease (AD). A major Aβ clearance pathway in the brain is cellular uptake and degradation. However, how Aβ traffics through the endocytic pathway and how AD risk factors regulate this event is unclear. Here we show that the majority of endocytosed Aβ in neurons traffics through early and late endosomes to the lysosomes for degradation. Overexpression of Rab5 or Rab7, small GTPases that function in vesicle fusion for early and late endosomes, respectively, significantly accelerates Aβ endocytic trafficking to the lysosomes. We also found that a portion of endocytosed Aβ traffics through Rab11-positive recycling vesicles. A blockage of this Aβ recycling pathway with a constitutively active Rab11 mutant significantly accelerates cellular Aβ accumulation. Inhibition of lysosomal enzymes results in Aβ accumulation and aggregation. Importantly, apolipoprotein E (apoE) accelerates neuronal Aβ uptake, lysosomal trafficking, and degradation in an isoform-dependent manner with apoE3 more efficiently facilitating Aβ trafficking and degradation than apoE4, a risk factor for AD. Taken together, our results demonstrate that Aβ endocytic trafficking to lysosomes for degradation is a major Aβ clearance pathway that is differentially regulated by apoE isoforms. A disturbance of this pathway can lead to accumulation and aggregation of cellular Aβ capable of causing neurotoxicity and seeding amyloid.

  15. A possible role of apolipoprotein E polymorphism in predisposition to higher education.

    PubMed

    Hubacek, J A; Pitha, J; Skodová, Z; Adámková, V; Lánská, V; Poledne, R

    2001-01-01

    A potential candidate gene that could contribute to the education process is the apolipoprotein E (apo E) gene that has been shown to correlate with memory function and memory decline. We measured apo E polymorphism in groups of probands with different levels of education selected from a population sample. In the group of probands with higher education (n = 82), 24.4% had the e4 allele, compared with 7.3% who had the e2 allele. A reverse association was found in the group that left school aged 15 (n = 36) - 8.3% had the e4 allele and 13.9% had the e2 allele. Eighty-seven percent of the probands with the allele e4 reached higher education, compared to only 54.5% with the allele e2. The difference between the groups is statistically significant (p = 0.039), and this may indicate some role for the apo E polymorphism in subjects' intelligence or ability to learn.

  16. Low Density Lipoprotein Receptor-Related Protein and Apolipoprotein E Expression is Altered in Schizophrenia

    PubMed Central

    Gibbons, Andrew Stuart; Thomas, Elizabeth A.; Scarr, Elizabeth; Dean, Brian

    2010-01-01

    Our recent microarray study reported altered mRNA expression of several low density lipoprotein receptor-related proteins (LRP) associated with the first 4 years following diagnosis with schizophrenia. Whilst this finding is novel, apolipoprotein E (APOE), which mediates its activity through LRPs, has been reported by several studies to be altered in brains of subjects with schizophrenia. We used qPCR to measure the expression of LRP2, LRP4, LRP6, LRP8, LRP10 and LRP12 mRNA in Brodmann's area (BA) 46 of the dorsolateral prefrontal cortex in 15 subjects with short duration of illness schizophrenia (SDS) and 15 pair matched controls. We also used Western blotting to measure APOE protein expression in BA46 from these subjects. Amongst the LRPs examined, LRP10 expression was significantly increased (P = 0.03) and LRP12 was significantly decreased (P < 0.01) in SDS. APOE protein expression was also increased in SDS (P = 0.01). No other marker examined in this study was altered with diagnosis. Our data supports a role for distinct members of the LRP family in the pathology of schizophrenia and adds weight to the hypothesis that aberrant apolipoprotein signaling is involved in the early stages of schizophrenia. PMID:21423430

  17. Apolipoprotein E polymorphisms increase the risk of post-stroke depression

    PubMed Central

    Li, Xue-bin; Wang, Jie; Xu, An-ding; Huang, Jian-min; Meng, Lan-qing; Huang, Rui-ya; Wang, Jun-li

    2016-01-01

    Recent reports have shown that apolipoprotein E (APOE) polymorphisms are involved in neurodegenerative disease. However, it is unclear whether APOE affects post-stroke depression. Accordingly, we hypothesized that APOE polymorphisms modify the risk of post-stroke depression. Here, we performed a hospital-based case-control study (including 76 cerebral infarction cases with post-stroke depression, 88 cerebral infarction cases without post-stroke depression, and 109 controls without any evidence of post-stroke depression or cerebral infarction) to determine possible association between APOE rs429358 and rs7412 polymorphisms and risk of post-stroke depression. Our findings show no difference among the groups with regards genotype distribution of the rs7412 polymorphism. In contrast, APOE genotypes with rs429358-C alleles increased the risk of post-stroke depression. Further, the rs429358 polymorphism was associated with significantly decreased regional cerebral blood flow values in the left temporal lobe of post-stroke depression cases. Additionally, the rs429358 polymorphism was not only associated with depression severity, but with increasing serum levels of total cholesterol. These results suggest that the APOE rs429358 polymorphism is associated with increased risk of developing post-stroke depression, and that APOE rs429358-C allele genotypes may be detrimental to recovery of nerve function after stoke. Indeed, these findings provide clinical data for future post-stroke depression gene interventions. PMID:28123423

  18. Bexarotene protects against traumatic brain injury in mice partially through apolipoprotein E.

    PubMed

    Zhong, Jianjun; Cheng, Chongjie; Liu, Han; Huang, Zhijian; Wu, Yue; Teng, Zhipeng; He, Junchi; Zhang, Hongrong; Wu, Jinchuan; Cao, Fang; Jiang, Li; Sun, Xiaochuan

    2017-02-20

    Bexarotene has been proved to have neuroprotective effects in many animal models of neurological diseases. However, its neuroprotection in traumatic brain injury (TBI) is still unknown. This study aims to explore the neuroprotective effects of bexarotene on TBI and its possible mechanism. Controlled cortical impact (CCI) model was used to simulate TBI in C57BL/6 mice as well as APOE gene knockout (APOE-KO) mice. After CCI, mice were daily dosed with bexarotene or vehicle solution intraperitoneally. The motor function, learning and memory, inflammatory factors, microglia amount, apoptosis condition around injury site and main side-effects were all measured. The results showed that, after CCI, bexarotene treatment markedly improved the motor function and spatial memory in C57BL/6 compare to APOE-KO mice which showed no improvement. The inflammatory cytokines, microglia amount, cell apoptosis rate, and protein of cleaved caspase-3 around the injury site were markedly upregulated after TBI in both C57BL/6 and APOE-KO mice, and all these upregulation were significantly mitigated by bexarotene treatment in C57BL/6 mice, but not in APOE-KO mice. No side-effects were detected after consecutive administration. Taken together, bexarotene inhibits the inflammatory response as well as cell apoptosis and improves the neurological function of mice after TBI partially through apolipoprotein E. This may make it a promising candidate for the therapeutic treatment after TBI.

  19. An Apolipoprotein E-Mimetic Stimulates Axonal Regeneration and Remyelination after Peripheral Nerve Injury

    PubMed Central

    Fowler, Kenneth A.; Neil, Jessica E.; Colton, Carol A.; Vitek, Michael P.

    2010-01-01

    Elevated apolipoprotein E (apoE) synthesis within crushed sciatic nerves advocates that apoE could benefit axonal repair and reconstruction of axonal and myelin membranes. We created an apoE-mimetic peptide, COG112 (acetyl-RQIKIWFQNRRMKWKKCLRVRLASHLRKLRKRLL-amide), and found that postinjury treatment with COG112 significantly improved recovery of motor and sensory function following sciatic nerve crush in C57BL/6 mice. Morphometric analysis of injured sciatic nerves revealed that COG112 promoted axonal regrowth after 2 weeks of treatment. More strikingly, the thickness of myelin sheaths was increased by COG112 treatment. Consistent with these histological findings, COG112 potently elevated growth associated protein 43 (GAP-43) and peripheral myelin protein zero (P0), which are markers of axon regeneration and remyelination, respectively. Electron microscopic examination further suggested that the apoE-mimetic COG112 may increase clearance of myelin debris. Schwann cell uptake of cholesterol-containing low-density lipoprotein particles was selectively enhanced by COG112 treatment in a Schwann cell line S16. Moreover, COG112 significantly promoted axon elongation in primary dorsal root ganglion cultures from rat pups. Considering that cholesterol and lipids are needed for reconstructing myelin sheaths and axon extension, these data support a hypothesis where supplementation with exogenous apoE-mimetics such as COG112 may be a promising strategy for restoring lost functional and structural elements following nerve injury. PMID:20406857

  20. Apolipoprotein E4 Genotype Does Not Increase Risk of HIV-associated Neurocognitive Disorders

    PubMed Central

    Morgan, E.E.; Woods, S.P.; Letendre, S.L.; Franklin, D.R.; Bloss, C.; Goate, A.; Heaton, R.K.; Collier, A.C.; Marra, C.M.; Gelman, B.B.; McArthur, J.C.; Morgello, S.; Simpson, D.M.; McCutchan, J.A.; Ellis, R.J.; Abramson, I.; Gamst, A.; Fennema-Notestine, C.; Smith, D.M.; Grant, I.; Vaida, F.; Clifford, D.B.

    2013-01-01

    This is a cross-sectional, observational study to evaluate the hypothesis that HIV-seropositive (HIV+) apolipoprotein E4 (APOE4) carriers are at increased risk for HIV-associated Neurocognitive Disorders (HAND) compared to APOE4 noncarriers with HIV in the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) Group sample. APOE genotype was determined in 466 CHARTER participants with varying disease stages and histories of antiretroviral treatment who did not have severe psychiatric or medical comorbid conditions that preclude diagnosis of HAND. HAND diagnoses were based on results of comprehensive neurobehavioral evaluation and use of current neuroAIDS diagnostic criteria. HAND status consisting of two levels: neuropsychologically normal status (i.e., no HAND) and any HAND diagnosis (i.e., asymptomatic neurocognitive impairment, minor neurocognitive disorder, HIV-associated dementia). Logistic regression analyses revealed no association between APOE4 carrier status and HAND, and there were no interactions between APOE4 carrier status and ethnicity, age, substance use disorders, duration of infection, or nadir CD4. Results did not differ when analysis was restricted to symptomatic HAND, and no APOE4 gene dose-dependent relationship to HAND emerged. APOE4 status was not associated with concurrent HAND in this large, well-characterized sample. This does not preclude emergence of an association between APOE4 status and HAND as this population ages. Prospective, longitudinal studies are needed to examine APOE4 as a risk factor for neurocognitive decline, incident HAND at older ages, and potential associations with CSF amyloid. PMID:23408335

  1. Consumption of hydrogen water prevents atherosclerosis in apolipoprotein E knockout mice.

    PubMed

    Ohsawa, Ikuroh; Nishimaki, Kiyomi; Yamagata, Kumi; Ishikawa, Masahiro; Ohta, Shigeo

    2008-12-26

    Oxidative stress is implicated in atherogenesis; however most clinical trials with dietary antioxidants failed to show marked success in preventing atherosclerotic diseases. We have found that hydrogen (dihydrogen; H(2)) acts as an effective antioxidant to reduce oxidative stress [I. Ohsawa, M. Ishikawa, K. Takahashi, M. Watanabe, K. Nishimaki, K. Yamagata, K. Katsura, Y. Katayama, S, Asoh, S. Ohta, Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals, Nat. Med. 13 (2007) 688-694]. Here, we investigated whether drinking H(2)-dissolved water at a saturated level (H(2)-water) ad libitum prevents arteriosclerosis using an apolipoprotein E knockout mouse (apoE(-/-)), a model of the spontaneous development of atherosclerosis. ApoE(-/-) mice drank H(2)-water ad libitum from 2 to 6 month old throughout the whole period. Atherosclerotic lesions were significantly reduced by ad libitum drinking of H(2)-water (p=0.0069) as judged by Oil-Red-O staining series of sections of aorta. The oxidative stress level of aorta was decreased. Accumulation of macrophages in atherosclerotic lesions was confirmed. Thus, consumption of H(2)-dissolved water has the potential to prevent arteriosclerosis.

  2. Apolipoprotein E in the genetics and epidemiology of Alzheimer`s disease

    SciTech Connect

    Hardy, J.

    1995-10-09

    The role of apolipoprotein E (ApoE) alleles and isoforms in the etiology and pathogenesis of Alzheimer`s disease is discussed. The possibility that ApoE itself is not involved in the disease pathogenesis but is merely in genetic disequilibrium with the real locus is discussed and dismissed. The data showing that the {epsilon}4 allele is associated with an increased risk of developing the disease and with an earlier onset age are reviewed. The data showing that, at least in some circumstances, the {epsilon}2 allele is associated with a decrease in the risk of developing the disease, and with a later onset age are also reviewed. Data from the genetic analysis of other disorders are reviewed and presented, and it is suggested that the genetic data support the notion that the role of ApoE in the etiology of the disease directly relates to {beta}-amyloid deposition and plaque formation. This suggestion is in concordance with the most likely mechanism for the role of P-amyloid precursor protein gene mutations as other risk factors for the disease. 68 refs.

  3. Increased sensitivity of apolipoprotein E knockout mice to copper-induced oxidative injury to the liver.

    PubMed

    Chen, Yuan; Li, Bin; Zhao, Ran-ran; Zhang, Hui-feng; Zhen, Chao; Guo, Li

    2015-04-10

    Apolipoprotein E (ApoE) genotypes are related to clinical presentations in patients with Wilson's disease, indicating that ApoE may play an important role in the disease. However, our understanding of the role of ApoE in Wilson's disease is limited. High copper concentration in Wilson's disease induces excessive generation of free oxygen radicals. Meanwhile, ApoE proteins possess antioxidant effects. We therefore determined whether copper-induced oxidative damage differ in the liver of wild-type and ApoE knockout (ApoE(-/-)) mice. Both wild-type and ApoE(-/-) mice were intragastrically administered with 0.2 mL of copper sulfate pentahydrate (200 mg/kg; a total dose of 4 mg/d) or the same volume of saline daily for 12 weeks, respectively. Copper and oxidative stress markers in the liver tissue and in the serum were assessed. Our results showed that, compared with the wild-type mice administered with copper, TBARS as a marker of lipid peroxidation, the expression of oxygenase-1 (HO-1), NAD(P)H dehydrogenase, and quinone 1 (NQO1) significantly increased in the ApoE(-/-) mice administered with copper, meanwhile superoxide dismutase (SOD) activity significantly decreased. Thus, it is concluded that ApoE may protect the liver from copper-induced oxidative damage in Wilson's disease.

  4. Evolutionary analysis of apolipoprotein E by Maximum Likelihood and complex network methods

    PubMed Central

    Benevides, Leandro de Jesus; de Carvalho, Daniel Santana; Andrade, Roberto Fernandes Silva; Bomfim, Gilberto Cafezeiro; Fernandes, Flora Maria de Campos

    2016-01-01

    Abstract Apolipoprotein E (apo E) is a human glycoprotein with 299 amino acids, and it is a major component of very low density lipoproteins (VLDL) and a group of high-density lipoproteins (HDL). Phylogenetic studies are important to clarify how various apo E proteins are related in groups of organisms and whether they evolved from a common ancestor. Here, we aimed at performing a phylogenetic study on apo E carrying organisms. We employed a classical and robust method, such as Maximum Likelihood (ML), and compared the results using a more recent approach based on complex networks. Thirty-two apo E amino acid sequences were downloaded from NCBI. A clear separation could be observed among three major groups: mammals, fish and amphibians. The results obtained from ML method, as well as from the constructed networks showed two different groups: one with mammals only (C1) and another with fish (C2), and a single node with the single sequence available for an amphibian. The accordance in results from the different methods shows that the complex networks approach is effective in phylogenetic studies. Furthermore, our results revealed the conservation of apo E among animal groups. PMID:27560837

  5. Apolipoprotein E and lipid homeostasis in the etiology and treatment of sporadic Alzheimer's disease.

    PubMed

    Poirier, Judes; Miron, Justin; Picard, Cynthia; Gormley, Patrick; Théroux, Louise; Breitner, John; Dea, Doris

    2014-09-01

    The discovery that the apolipoprotein E (apoE) ε4 allele is genetically linked to both sporadic and familial late-onset Alzheimer's disease (AD) raises the possibility that a dysfunction of the lipid transport system could seriously affect lipid homeostasis in the brain of AD subjects. The presence of the ε4 allele has been associated with lower levels of apoE in both serum and brain tissues of normal and AD subjects. In an attempt to reverse the apoE deficit in AD, we identified and characterized several apoE inducer agents using a low-throughput in vitro screening assay. The most promising of these compounds is called probucol. Administration of probucol, an old cholesterol-lowering drug, in a pilot trial in mild-to-moderate sporadic AD led to a significant increase in cerebrospinal fluid (CSF) apoE levels and a decrease in CSF in both phosphorylated tau 181 and beta-amyloid 1-42 concentrations without significant modifications of lipid hydroperoxide levels.

  6. An apolipoprotein E-mimetic stimulates axonal regeneration and remyelination after peripheral nerve injury.

    PubMed

    Li, Feng-Qiao; Fowler, Kenneth A; Neil, Jessica E; Colton, Carol A; Vitek, Michael P

    2010-07-01

    Elevated apolipoprotein E (apoE) synthesis within crushed sciatic nerves advocates that apoE could benefit axonal repair and reconstruction of axonal and myelin membranes. We created an apoE-mimetic peptide, COG112 (acetyl-RQIKIWFQNRRMKWKKCLRVRLASHLRKLRKRLL-amide), and found that postinjury treatment with COG112 significantly improved recovery of motor and sensory function following sciatic nerve crush in C57BL/6 mice. Morphometric analysis of injured sciatic nerves revealed that COG112 promoted axonal regrowth after 2 weeks of treatment. More strikingly, the thickness of myelin sheaths was increased by COG112 treatment. Consistent with these histological findings, COG112 potently elevated growth associated protein 43 (GAP-43) and peripheral myelin protein zero (P0), which are markers of axon regeneration and remyelination, respectively. Electron microscopic examination further suggested that the apoE-mimetic COG112 may increase clearance of myelin debris. Schwann cell uptake of cholesterol-containing low-density lipoprotein particles was selectively enhanced by COG112 treatment in a Schwann cell line S16. Moreover, COG112 significantly promoted axon elongation in primary dorsal root ganglion cultures from rat pups. Considering that cholesterol and lipids are needed for reconstructing myelin sheaths and axon extension, these data support a hypothesis where supplementation with exogenous apoE-mimetics such as COG112 may be a promising strategy for restoring lost functional and structural elements following nerve injury.

  7. Olive oils modulate fatty acid content and signaling protein expression in apolipoprotein E knockout mice brain.

    PubMed

    Alemany, Regina; Navarro, María A; Vögler, Oliver; Perona, Javier S; Osada, Jesús; Ruiz-Gutiérrez, Valentina

    2010-01-01

    Atherosclerosis contributes to disruption of neuronal signaling pathways by producing lipid-dependent modifications of brain plasma membranes, neuroinflammation and oxidative stress. We investigated whether long-term (11 weeks) consumption of refined- (ROO) and pomace- (POO) olive oil modulated the fatty acid composition and the levels of membrane signaling proteins in the brain of apolipoprotein E (apoE) knockout (KO) mice, an animal model of atherosclerosis. Both of these oils are rich in bioactive molecules with anti-inflammatory and antioxidant effects. ROO and POO long-term consumption increased the proportion of monounsaturated fatty acids (MUFAs), particularly of oleic acid, while reducing the level of the saturated fatty acids (SFAs) palmitic and stearic acid. As a result, the MUFA:SFA ratio was higher in apoE KO mice brain fed with ROO and POO. Furthermore, both oils reduced the level of arachidonic and eicosapentaenoic acid, suggesting a decrease in the generation of pro- and anti-inflammatory eicosanoids. Finally, ROO and POO induced an increase in the density of membrane proteins implicated in both the Galphas/PKA and Galphaq/PLCbeta1/PKCalpha signaling pathways. The combined effects of long-term ROO and POO consumption on fatty acid composition and the level of signaling proteins involved in PKA and PKC activation, suggest positive effects on neuroinflammation and brain function in apoE KO mice brain, and convert these oils into promising functional foods in diseases involving apoE deficiency.

  8. Solid lipid nanoparticles as a vehicle for brain-targeted drug delivery: two new strategies of functionalization with apolipoprotein E

    NASA Astrophysics Data System (ADS)

    Rute Neves, Ana; Fontes Queiroz, Joana; Weksler, Babette; Romero, Ignacio A.; Couraud, Pierre-Olivier; Reis, Salette

    2015-12-01

    Nanotechnology can be an important tool to improve the permeability of some drugs for the blood-brain barrier. In this work we created a new system to enter the brain by functionalizing solid lipid nanoparticles with apolipoprotein E, aiming to enhance their binding to low-density lipoprotein receptors on the blood-brain barrier endothelial cells. Solid lipid nanoparticles were successfully functionalized with apolipoprotein E using two distinct strategies that took advantage of the strong interaction between biotin and avidin. Transmission electron microscopy images revealed spherical nanoparticles, and dynamic light scattering gave a Z-average under 200 nm, a polydispersity index below 0.2, and a zeta potential between -10 mV and -15 mV. The functionalization of solid lipid nanoparticles with apolipoprotein E was demonstrated by infrared spectroscopy and fluorimetric assays. In vitro cytotoxic effects were evaluated by MTT and LDH assays in the human cerebral microvascular endothelial cells (hCMEC/D3) cell line, a human blood-brain barrier model, and revealed no toxicity up to 1.5 mg ml-1 over 4 h of incubation. The brain permeability was evaluated in transwell devices with hCMEC/D3 monolayers, and a 1.5-fold increment in barrier transit was verified for functionalized nanoparticles when compared with non-functionalized ones. The results suggested that these novel apolipoprotein E-functionalized nanoparticles resulted in dynamic stable systems capable of being used for an improved and specialized brain delivery of drugs through the blood-brain barrier.

  9. Electrochemical, spectral, and computational studies of metalloporphyrin dimers formed by cation complexation of crown ether cavities.

    PubMed

    Chitta, Raghu; Rogers, Lisa M; Wanklyn, Amber; Karr, Paul A; Kahol, Pawan K; Zandler, Melvin E; D'Souza, Francis

    2004-11-01

    The effect on the electrochemical oxidation and reduction potentials of 5,10,15,20-tetrakis(benzo-15-crown-5)porphyrin (TCP) and its metal derivatives (MTCP; M = Mg(II), VO(IV), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Ag(II)) upon potassium ion induced dimerization of the porphyrins was systematically performed in benzonitrile containing 0.1 M (TBA)ClO(4) by differential pulse voltammetry technique. The HOMO--LUMO energy level diagram constructed from the electrochemical data revealed destabilization of the HOMO level and stabilization of the LUMO level upon dimer formation while such a perturbation was larger for the HOMO level than the LUMO level. The geometry and electronic structure of a representative ZnTCP and its dimer, K(4)(ZnTCP)(2), were evaluated by the ab initio B3LYP method utilizing a mixed basis set of 3-21G(*) for Zn, K, O, and N and STO-3G for C and H. The inter-porphyrin ring distance of the dimer calculated from the optimized geometry agreed with the spectroscopically determined one, and the calculated HOMO and LUMO frontier orbitals revealed delocalization on both of the porphyrins rings. The metal-metal distances calculated from the triplet ESR spectra of the K(+) induced porphyrin dimers bearing paramagnetic metal ions in the cavity followed the trend Cu--Cu < VO--VO < Ag--Ag. However, the spectral shifts resulting from the exciton coupling of the interacting porphyrin pi-systems revealed no specific trend with respect to the metal ion in the porphyrin cavity. Additionally, linear trends in the electrochemically measured HOMO--LUMO gap and the energy corresponding to the most intense visible band of both MTCP and K(4)(MTCP)(2) were observed. A reduced HOMO--LUMO gap predicted for the dimer by B3LYP/(3-21G(), STO-3G) calculations was confirmed by the results of optical absorption and electrochemical studies.

  10. Apolipoprotein E expression and behavioral toxicity of high charge, high energy (HZE) particle radiation

    NASA Technical Reports Server (NTRS)

    Higuchi, Yoshinori; Nelson, Gregory A.; Vazquez, Marcelo; Laskowitz, Daniel T.; Slater, James M.; Pearlstein, Robert D.

    2002-01-01

    Apolipoprotein E (apoE) is a lipid binding protein that plays an important role in tissue repair following brain injury. In the present studies, we have investigated whether apoE affects the behavioral toxicity of high charge, high energy (HZE) particle radiation. METHODS: Sixteen male apoE knockout (KO) mice and sixteen genetically matched wild-type (WT) C57BL mice were used in this experiment. Half of the KO and half of the WT animals were irradiated with 600 MeV/amu iron particles (2 Gy whole body). The effect of irradiation on motor coordination and stamina (Rotarod test), exploratory behavior (open field test), and spatial working and reference memory (Morris water maze) was assessed. ROTAROD TEST: Performance was adversely affected by radiation exposure in both KO and WT groups at 30 d after irradiation. By 60 d after radiation, the radiation effect was lost in WT, but still apparent in irradiated KO mice. OPEN FIELD TEST: Radiation reduced open field exploratory activity 14, 28, 56, 84, and 168 d after irradiation of KO mice, but had no effect on WT mice. MORRIS WATER MAZE: Radiation adversely affected spatial working memory in the KO mice, but had no discernible effect in the WT mice as assessed 180 d after irradiation. In contrast, irradiated WT mice showed marked impairment of spatial reference memory in comparison to non-irradiated mice, while no effect of radiation was observed in KO mice. CONCLUSIONS: These studies show that apoE expression influences the behavioral toxicity of HZE particle radiation and suggest that apoE plays a role in the repair/recovery from radiation injury of the CNS. ApoE deficiency may exacerbate the previously reported effects of HZE particle radiation in accelerating the brain aging process.

  11. AN APOLIPOPROTEIN E4 FRAGMENT CAN PROMOTE INTRACELLULAR ACCUMULATION OF AMYLOID PEPTIDE BETA 42

    PubMed Central

    Dafnis, Ioannis; Stratikos, Efstratios; Tzinia, Athina; Tsilibary, Effie C.; Zannis, Vassilis I.; Chroni, Angeliki

    2010-01-01

    Apolipoprotein E (apoE) plays a crucial role in lipid transport in circulation and the brain. The apoE4 isoform is a major risk factor for Alzheimer's disease (AD). ApoE4 is more susceptible to proteolysis than other apoE isoforms and apoE4 fragments have been found in brains of AD patients. These apoE4 fragments have been hypothesized to be involved in the pathogenesis of AD, although the mechanism is not clear. In this study we examined the effect of lipid-free apoE4 on amyloid precursor protein (APP) processing and Aβ40 and Aβ42 levels in human neuroblastoma SK-N-SH cells. We discovered that a specific apoE4 fragment, apoE4[Δ(166-299)], can promote the cellular uptake of extracellular Aβ40 and Aβ42 either generated after APP transfection or added exogenously. A longer length fragment, apoE4[Δ(186-299)], or full-length apoE4 failed to elicit this effect. ApoE4[Δ(166-299)] effected a 20% reduction of cellular sphingomyelin levels, as well as changes in cellular membrane micro-fluidity. Following uptake, approximately 50% of Aβ42 remained within the cell for at least 24h, and led to increased formation of reactive oxygen species. Overall, our findings suggest a direct link between two early events in the pathogenesis of AD, apoE4 proteolysis and intraneuronal presence of Aβ. PMID:20412390

  12. A FDG-PET Study of Metabolic Networks in Apolipoprotein E ε4 Allele Carriers.

    PubMed

    Yao, Zhijun; Hu, Bin; Zheng, Jiaxiang; Zheng, Weihao; Chen, Xuejiao; Gao, Xiang; Xie, Yuanwei; Fang, Lei

    2015-01-01

    Recently, some studies have applied the graph theory in brain network analysis in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). However, relatively little research has specifically explored the properties of the metabolic network in apolipoprotein E (APOE) ε4 allele carriers. In our study, all the subjects, including ADs, MCIs and NCs (normal controls) were divided into 165 APOE ε4 carriers and 165 APOE ε4 noncarriers. To establish the metabolic network for all brain regions except the cerebellum, cerebral glucose metabolism data obtained from FDG-PET (18F-fluorodeoxyglucose positron emission tomography) were segmented into 90 areas with automated anatomical labeling (AAL) template. Then, the properties of the networks were computed to explore the between-group differences. Our results suggested that both APOE ε4 carriers and noncarriers showed the small-world properties. Besides, compared with APOE ε4 noncarriers, the carriers showed a lower clustering coefficient. In addition, significant changes in 6 hub brain regions were found in between-group nodal centrality. Namely, compared with APOE ε4 noncarriers, significant decreases of the nodal centrality were found in left insula, right insula, right anterior cingulate, right paracingulate gyri, left cuneus, as well as significant increases in left paracentral lobule and left heschl gyrus in APOE ε4 carriers. Increased local short distance interregional correlations and disrupted long distance interregional correlations were found, which may support the point that the APOE ε4 carriers were more similar with AD or MCI in FDG uptake. In summary, the organization of metabolic network in APOE ε4 carriers indicated a less optimal pattern and APOE ε4 might be a risk factor for AD.

  13. Xyloketal B Attenuates Atherosclerotic Plaque Formation and Endothelial Dysfunction in Apolipoprotein E Deficient Mice

    PubMed Central

    Zhao, Li-Yan; Li, Jie; Yuan, Feng; Li, Mei; Zhang, Quan; Huang, Yun-Ying; Pang, Ji-Yan; Zhang, Bin; Sun, Fang-Yun; Sun, Hong-Shuo; Li, Qian; Cao, Lu; Xie, Yu; Lin, Yong-Cheng; Liu, Jie; Tan, Hong-Mei; Wang, Guan-Lei

    2015-01-01

    Our previous studies demonstrated that xyloketal B, a novel marine compound with a unique chemical structure, has strong antioxidant actions and can protect against endothelial injury in different cell types cultured in vitro and model organisms in vivo. The oxidative endothelial dysfunction and decrease in nitric oxide (NO) bioavailability are critical for the development of atherosclerotic lesion. We thus examined whether xyloketal B had an influence on the atherosclerotic plaque area in apolipoprotein E-deficient (apoE−/−) mice fed a high-fat diet and investigated the underlying mechanisms. We found in our present study that the administration of xyloketal B dose-dependently decreased the atherosclerotic plaque area both in the aortic sinus and throughout the aorta in apoE−/− mice fed a high-fat diet. In addition, xyloketal B markedly reduced the levels of vascular oxidative stress, as well as improving the impaired endothelium integrity and NO-dependent aortic vasorelaxation in atherosclerotic mice. Moreover, xyloketal B significantly changed the phosphorylation levels of endothelial nitric oxide synthase (eNOS) and Akt without altering the expression of total eNOS and Akt in cultured human umbilical vein endothelial cells (HUVECs). Here, it increased eNOS phosphorylation at the positive regulatory site of Ser-1177, while inhibiting phosphorylation at the negative regulatory site of Thr-495. Taken together, these findings indicate that xyloketal B has dramatic anti-atherosclerotic effects in vivo, which is partly due to its antioxidant features and/or improvement of endothelial function. PMID:25874925

  14. Effects of Apolipoprotein E Isoforms in Diabetic Nephropathy of Chinese Type 2 Diabetic Patients

    PubMed Central

    Ma, Liang; Han, ChengWu; Liu, Qian; Cong, Xiao; Xu, YaPing; Zhao, TingTing

    2017-01-01

    Diabetic nephropathy (DN) is one of the major chronic complications of diabetes. Genetic polymorphism of Apolipoprotein E (ApoE) has been proposed to participating in DN. The purpose of the study was to evaluate the relationship between ApoE genetic polymorphism and the presence of DN in Chinese type 2 diabetic patients. We studied 845 diabetic patients who were divided into DN group (n = 429) and control group (n = 416). ApoE genotype was determined by ApoE genotyping chip and the plasmatic biochemical characterization was performed on all subjects. There were differences (P < 0.001) in HbA1c, creatinine, and urinary albumin between the two groups. The ApoE ε2 allelic frequency was 7.69% in DN group versus 3.49% in control group (OR = 2.22, 95% CI = 1.41–3.47, and P < 0.05), as expected, ApoE E2/E2 and E2/E3 genotype frequency were higher in DN group (13.75% versus 6.49%, P < 0.05). The ApoE ε4 allelic frequency was 7.93% in DN group versus 11.54% in control group (OR = 0.70, 95% CI = 0.50–0.97, and P < 0.05), and DN group presented a lower frequency of ApoE E3/E4 and E4/E4 genotype frequency (14.91% versus 19.96%, P < 0.05). These results suggest ApoE ε2 allele may be a risk factor; however ApoE ε4 allele may play a protective role of DN in Chinese type 2 diabetic patients. PMID:28326331

  15. Apolipoprotein E4 Elicits Lysosomal Cathepsin D Release, Decreased Thioredoxin-1 Levels, and Apoptosis

    PubMed Central

    Persson, Torbjörn; Lattanzio, Francesca; Calvo-Garrido, Javier; Rimondini, Roberto; Rubio-Rodrigo, Marta; Sundström, Erik; Maioli, Silvia; Sandebring-Matton, Anna; Cedazo-Mínguez, Ángel

    2016-01-01

    The major genetic risk factor for Alzheimer’s disease (AD), apolipoprotein E4 (ApoE4), has been suggested to have detrimental effects on neurons, including direct toxicity via apoptosis. Thioredoxin-1 (Trx1) is an endogenous antioxidant protein important for redox regulation and participates in the regulation of apoptosis through the inhibition of apoptosis signal-regulating kinase-1 (Ask-1). In this study, we have investigated the effects of ApoE on Trx1 in the brain. Our results showed that the protein levels of Trx1 were reduced in the hippocampus of ApoE4 targeted replacement (TR) mice compared to ApoE3 TR mice. The reduction was also seen in vitro after treatment of both human primary cortical neurons and neuroblastoma cells with human recombinant ApoE4 (rApoE4). Furthermore, ApoE4 caused a disruption of lysosomal integrity and a shift in the localization of Cathepsin D, an enzyme known to degrade Trx1. ApoE4 treatment induced in addition apoptosis through translocation of Death-domain associated protein-6 (Daxx) from the nucleus to the cytosol, suggesting an activation of the Ask-1 pathway. This toxicity was prevented by overexpression of Trx1 and other endogenous Ask-1 inhibitors. Our data suggests that down-regulation of Trx1 is involved in the toxicity caused by ApoE4. An activated ASK-1 pathway might indeed make cells more vulnerable to other insults such as amyloid-β, which could partially explain the mechanism behind the strongest genetic risk factor for AD. PMID:28035917

  16. Cognitive deficits and disruption of neurogenesis in a mouse model of apolipoprotein E4 domain interaction.

    PubMed

    Adeosun, Samuel O; Hou, Xu; Zheng, Baoying; Stockmeier, Craig; Ou, Xiaoming; Paul, Ian; Mosley, Thomas; Weisgraber, Karl; Wang, Jun Ming

    2014-01-31

    Apolipoprotein E4 (apoE4) allele is the major genetic risk factor for sporadic Alzheimer disease (AD) due to the higher prevalence and earlier onset of AD in apoE4 carriers. Accumulating data suggest that the interaction between the N- and the C-terminal domains in the protein may be the main pathologic feature of apoE4. To test this hypothesis, we used Arg-61 mice, a model of apoE4 domain interaction, by introducing the domain interaction feature of human apoE4 into native mouse apoE. We carried out hippocampus-dependent learning and memory tests and related cellular and molecular assays on 12- and 3-month-old Arg-61 and age-matched background C57BL/6J mice. Learning and memory task performance were impaired in Arg-61 mice at both old and young ages compared with C57BL/6J mice. Surprisingly, young Arg-61 mice had more mitotic doublecortin-positive cells in the subgranular zone; mRNA levels of brain-derived neurotrophic factor (BDNF) and TrkB were also higher in 3-month-old Arg-61 hippocampus compared with C57BL/6J mice. These early-age neurotrophic and neurogenic (proliferative) effects in the Arg-61 mouse may be an inadequate compensatory but eventually detrimental attempt by the system to "repair" itself. This is supported by the higher cleaved caspase-3 levels in the young animals that not only persisted, but increased in old age, and the lower levels of doublecortin at old age in the hippocampus of Arg-61 mice. These results are consistent with human apoE4-dependent cognitive and neuro-pathologic changes, supporting the principal role of domain interaction in the pathologic effect of apoE4. Domain interaction is, therefore, a viable therapeutic/prophylactic target for cognitive impairment and AD in apoE4 subjects.

  17. Association between Apolipoprotein E genotype and cerebral palsy is not confirmed in a Caucasian population.

    PubMed

    McMichael, Gai L; Gibson, Catherine S; Goldwater, Paul N; Haan, Eric A; Priest, Kevin; Dekker, Gustaaf A; MacLennan, Alastair H

    2008-11-01

    Apolipoprotein E (APOE) plays a significant role in lipid metabolism and has been implicated in the growth and repair of injured neurons. Two small studies have suggested an association between APOE genotype and cerebral palsy. We investigated if APOE genotype is associated with an increased risk for cerebral palsy, influences the type of cerebral palsy or interacts with prenatal viral infection to influence risk of cerebral palsy. The population-based case-control study comprised newborn screening cards of 443 Caucasian patients with cerebral palsy and 883 Caucasian matched controls. APOE genotyping was performed on DNA extracted from dried blood spots. Allelic and genotypic frequencies did not differ between cases and controls and combined frequencies were 0.10 (epsilon2), 0.76 (epsilon3), 0.14 (epsilon4), 0.03 (epsilon2/epsilon2), 0.10 (epsilon2/epsilon3), 0.03 (epsilon2/epsilon4), 0.02 (epsilon4/epsilon4), 0.21 (epsilon3/epsilon4), 0.61 (epsilon3/epsilon3). APOE genotype was correlated with cerebral palsy, type of cerebral palsy, gestation at birth and the presence of viral nucleic acids detected in previous work. Analysis by gestational age (all gestational ages, >/=37, 32-36 and <32 weeks) and type of cerebral palsy (all types, diplegia, hemiplegia and quadriplegia) showed no association between APOE genotype and cerebral palsy in this Caucasian population. An association between prenatal viral infection, APOE genotype and cerebral palsy was not demonstrated. These results did not confirm an association between APOE genotype, cerebral palsy, type of cerebral palsy and prenatal infection in a Caucasian population. Given the low frequency of APOE epsilon2 and some of the heterozygote and homozygote combinations in this study, a larger study is assessing this further.

  18. Nitric oxide-releasing agent, LA419, reduces atherogenesis in apolipoprotein E-deficient mice.

    PubMed

    Carnicer, Ricardo; Guillén, Natalia; Arbonés-Mainar, José M; Navarro, María A; Guzmán, Mario A; Barranquero, Cristina; Arnal, Carmen; Gascón, Sonia; Acín, Sergio; Mourelle, Marisabel; Osada, Jesús

    2009-05-01

    LA419 is a novel nitric oxide-donor with antioxidant properties. The effect of this compound on the development of atherosclerosis was investigated in apolipoprotein E-deficient mice. Male mice were randomized to receive vehicle or 5 mg/kg/day LA419 for 12 weeks. At the end of this period, plasma lipid and lipoprotein parameters, oxidative stress markers and hepatic fat, and mRNA levels were measured as well as en face and cross-sectional lesion areas of the aorta. Data showed that LA419 administration reduced atherosclerotic foci and cross-sectional lesion areas by decreasing the intimae presence of macrophage-derived foam cells despite an increase in plasma cholesterol. This agent induced a significant reduction in body weight gain and mass of adipose tissue. Furthermore, compared with placebo, LA419 administration significantly reduced plasma triglycerides and apolipoprotein C-III levels as well as systemic oxidative stress, estimated by plasma 8-isoprostane. Conversely, nonesterified fatty acid and HDL cholesterol levels remained unchanged, as well as apolipoproteins A-I, A-IV, and B and paraoxonase activity. Plasma triglycerides were significantly associated with plasma levels of apolipoprotein C-III and hepatic Fsp27 mRNA expression. These results indicate that administration of LA419 modulates lesion development. These actions are partly independent of total cholesterol as well as HDL particles and related to triglyceridemia and oxidative stress. Hypotriglyceridemia is associated with an equal number of apoB-containing particles. Hence, LA419 administration could be used as a safe alternative to control the metabolic syndrome and atherosclerosis.

  19. Age-Related Effects of the Apolipoprotein E Gene on Brain Function.

    PubMed

    Matura, Silke; Prvulovic, David; Hartmann, Daniel; Scheibe, Monika; Sepanski, Beate; Butz, Marius; Oertel-Knöchel, Viola; Knöchel, Christian; Karakaya, Tarik; Fußer, Fabian; Hattingen, Elke; Pantel, Johannes

    2016-03-16

    The apolipoprotein E (ApoE) ɛ4 allele is a well-established genetic risk factor for sporadic Alzheimer's disease. Some evidence suggests a negative role of the ApoE ɛ4 allele for cognitive performance in late life, while beneficial effects on cognition have been shown in young age. We investigated age-related effects of the ApoE gene on brain function by assessing cognitive performance, as well as functional activation patterns during retrieval of Face-Name pairs in a group of young (n = 50; age 26.4±4.6 years, 25 ɛ4 carriers) and old (n = 40; age 66.1±7.0 years, 20 ɛ4 carriers) participants. A cross-sectional factorial design was used to examine the effects of age, ApoE genotype, and their interaction on both cognitive performance and the blood oxygenation level dependent (BOLD) brain response during retrieval of Face-Name pairs. While there were no genotype-related differences in cognitive performance, we found a significant interaction of age and ApoE genotype on task-related activation bilaterally in anterior cingulate gyrus and superior frontal gyrus, as well as left and right insula. Old age was associated with increased activity in ɛ4 carriers. The increased BOLD response in old ɛ4 carriers during retrieval could indicate a neurocognitive disadvantage associated with the ɛ4 allele with increasing age. Furthermore, recruitment of neuronal resources resulted in enhanced memory performance in young ɛ4 carriers, pointing to a better neurofunctional capacity associated with the ApoE4 genotype in young age.

  20. Apolipoprotein E ε4 modulates functional brain connectome in Alzheimer's disease.

    PubMed

    Wang, Jinhui; Wang, Xiao; He, Yi; Yu, Xin; Wang, Huali; He, Yong

    2015-05-01

    The apolipoprotein E (APOE) ɛ4 allele is a well-established genetic risk factor for Alzheimer's disease (AD). Recent research has demonstrated an APOE ɛ4-mediated modulation of intrinsic functional brain networks in cognitively normal individuals. However, it remains largely unknown whether and how APOE ɛ4 affects the brain's functional network architecture in patients with AD. Using resting-state functional MRI and graph-theory approaches, we systematically investigated the topological organization of whole-brain functional networks in 16 APOE ɛ4 carriers and 26 matched noncarriers with AD at three levels: global whole-brain, intermediate module, and regional node/connection. Neuropsychological analysis showed that the APOE ɛ4 carriers performed worse on delayed memory but better on a late item generation of a verbal fluency task (associated with executive function) than noncarriers. Whole-brain graph analyses revealed that APOE ɛ4 significantly disrupted whole-brain topological organization as characterized by (i) reduced parallel information transformation efficiency; (ii) decreased intramodular connectivity within the posterior default mode network (pDMN) and intermodular connectivity of the pDMN and executive control network (ECN) with other neuroanatomical systems; and (iii) impaired functional hubs and their rich-club connectivities that primarily involve the pDMN, ECN, and sensorimotor systems. Further simulation analysis indicated that these altered connectivity profiles of the pDMN and ECN largely accounted for the abnormal global network topology. Finally, the changes in network topology exhibited significant correlations with the patients' cognitive performances. Together, our findings suggest that the APOE genotype modulates large-scale brain networks in AD and shed new light on the gene-connectome interaction in this disease.

  1. Apolipoprotein E genotyping using PCR-GoldMag lateral flow assay and its clinical applications

    PubMed Central

    Lian, Ting; Hui, Wenli; Li, Xianying; Zhang, Chao; Zhu, Juanli; Li, Rui; Wan, Yinsheng; Cui, Yali

    2016-01-01

    A polymerase chain reaction-gold magnetic nanoparticles lateral flow assay (PCR-GoldMag LFA) has been developed via integrating multiplex amplification refractory mutation system PCR (multi-ARMS-PCR) with GoldMag-based LFA for the visual detection of single-nucleotide polymorphisms (SNPs). This assay was applied to genotype Apolipoprotein E (ApoE). ApoE genotyping is important due to the predictive value for the development of coronary artery disease and Alzheimer's disease. The method requires two steps: i) Simultaneous amplifications of the two polymorphic codons (ApoE 158 and 112), performed in separated reactions using multi-ARMS-PCR; and ii) detection of the wild-type and mutant PCR products via dual immunoreactions, which can be performed in ~5 min. Within two LFAs, anti-digoxin antibody-conjugated GoldMag probes bind digoxin-labeled wild-type PCR products, and anti-fluorescein isothiocyanate (FITC) antibody-conjugated GoldMag probes bind FITC-labeled mutant PCR products. All PCR products are biotin labeled and are detected by streptavidin-coated regions on the LFA strip, resulting in a red color. The current approach is capable of detecting the SNPs of ApoE in ~1.5 h, with a broad detection range from 10–1,000 ng of genomic DNA. Thus, the present protocol may facilitate simple, fast and cost-effective screening for important SNPs, as demonstrated by the evaluation of the prevalence of ApoE variants in a Han Chinese cohort. PMID:27665864

  2. Radiative-SPR platform for the detection of apolipoprotein E for use in medical diagnostics

    NASA Astrophysics Data System (ADS)

    Sciacca, Beniamino; Francois, Alexandre; Penno, Megan A. S.; Brazzatti, Julie A.; Klingler-Hoffmann, Manuela; Hoffmann, Peter; Monro, Tanya M.

    2012-03-01

    Surface Plasmon Resonance (SPR) based sensors enable the rapid, label-free and highly sensitive detection of a large range of biomolecules. We have previously shown that, using silver coated optical fibres with an high surface roughness, a re-scattering of the surface plasmons is possible, turning SPR into a radiative process. This approach overcomes limitations associated with current SPR technologies such as the tight tolerance on the metallic coating thickness, and results in a more compact, versatile, robust and cost-effective approach. However, the specific detection of small molecules is a challenge in SPR systems, regardless of the SPR architecture that is used. This new sensing platform, which has proved effective for the detection of large molecules such as viruses, is now demonstrated to be able to detect small proteins thanks to an improved surface functionalization procedure, a key point for reliable and robust immunosensors. Avidin, a tetrameric biotin-binding protein, was used to link biotinylated antibodies to the biotinylated surface, with a given orientation, to enable efficient sensing of the analyte. This approach may offer significant advantages compared to protein A surface functionalization strategies such as a limited cross reactivity with free IgG antibodies in clinical samples. We demonstrate that by bringing together this novel emission-based fibre SPR platform, with an improved surface functionalization process, is possible to rapidly and specifically detect human apolipoprotein E, a low molecular weight protein (~39kDa) known to be involved in cardiovascular diseases, in Alzheimer's disease and in gastric cancer. The results obtained clearly show that this new sensing platform has the potential to serve as a tool for point-of-decision medical diagnostics.

  3. Apolipoprotein E and Alzheimer disease: genotype-specific risks by age and sex.

    PubMed Central

    Bickeböller, H; Campion, D; Brice, A; Amouyel, P; Hannequin, D; Didierjean, O; Penet, C; Martin, C; Pérez-Tur, J; Michon, A; Dubois, B; Ledoze, F; Thomas-Anterion, C; Pasquier, F; Puel, M; Demonet, J F; Moreaud, O; Babron, M C; Meulien, D; Guez, D; Chartier-Harlin, M C; Frebourg, T; Agid, Y; Martinez, M; Clerget-Darpoux, F

    1997-01-01

    The distribution of apolipoprotein E (APOE) genotypes as a function of age and sex has been examined in a French population of 417 Alzheimer disease (AD) patients and 1,030 control subjects. When compared to the APOE epsilon3 allele, an increased risk associated with the APOE epsilon4 allele (odds ratio [OR] [epsilon4] = 2.7 with 95% confidence interval [CI] = 2.0-3.6; P < .001) and a protective effect of the APOE epsilon2 allele (OR[epsilon2] = 0.5 with 95% CI = 0.3-0.98; P = .012) were retrieved. An effect of the epsilon4 allele dosage on susceptibility was confirmed (OR[epsilon4/epsilon4] vs. the epsilon3/epsilon3 genotype = 11.2 [95% CI = 4.0-31.6]; OR[epsilon3/epsilon4] vs. the epsilon3/epsilon3 genotype = 2.2 [95% CI = 1.5-3.5]). The frequency of the epsilon4 allele was lower in male cases than in female cases, but, since a similar difference was found in controls, this does not lead to a difference in OR between sex. ORs for the epsilon4 allele versus the epsilon3 allele, OR(epsilon4), were not equal in all age classes: OR(epsilon4) in the extreme groups with onset at < 60 years or > 79 years were significantly lower than those from the age groups 60-79 years. In epsilon3/epsilon4 individuals, sex-specific lifetime risk estimates by age 85 years (i.e., sex-specific penetrances by age 85 years) were 0.14 (95% CI 0.04-0.30) for men and 0.17 (95% CI 0.09-0.28) for women. PMID:9012418

  4. Apolipoprotein E genetic polymorphism, serum lipoprotein levels and breast cancer risk: A case-control study

    PubMed Central

    CIBEIRA, GABRIELA HERRMANN; GIACOMAZZI, JULIANA; AGUIAR, ERNESTINA; SCHNEIDER, SILVANA; ETTRICH, BETINA; DE SOUZA, CAROLINE ISOPPO; CAMEY, SUZI; CALEFFI, MAIRA; WEBER, BERNARDETE; ASHTON-PROLLA, PATRICIA; MORIGUCHI, EMILIO HIDEYUKI

    2014-01-01

    The purpose of this study was to evaluate the association between apolipoprotein E (APOE) allelic frequency, serum lipoproteins and breast cancer (BC). We conducted a nested case-control study within a cohort including 47 cases and 165 controls. Polymerase chain reaction-restriction fragment length polymorphism analyses of the APOE polymorphism were performed. In general, participants with the genotype including alleles e2 and e3 tended to have lower serum triglycerides, total cholesterol and low-density lipoprotein cholesterol levels and higher high-density lipoprotein (HDL) cholesterol levels compared to participants homozygous for the e3 allele and participants heterozygous for the e3 and e4 alleles, respectively. BC patients exhibited higher mean levels of total serum cholesterol (P=0.070), dietary fat intake (P=0.020) and dietary cholesterol intake (P=0.017) compared to control subjects. The allelic distribution between the two groups revealed that the presence of the e2 allele was positively associated with the absence of BC, whereas the e4 allele was positively associated with the BC case group (P=0.019). The distribution of the APOE genotypes was not significantly different between cases and controls (P=0.172). The concomitant presence of the e2 and e4 alleles was positively associated with the absence of BC and e4/e4 homozygosity was positively associated with BC (P=0.021). Our findings suggested that APOE polymorphism plays an important role in the development of BC, particularly when associated with higher serum triglyceride levels. PMID:25279190

  5. Serum apolipoprotein E concentration and polymorphism influence serum lipid levels in Chinese Shandong Han population.

    PubMed

    Han, ShuYi; Xu, YiHui; Gao, MeiHua; Wang, YunShan; Wang, Jun; Liu, YanYan; Wang, Min; Zhang, XiaoQian

    2016-12-01

    Apolipoprotein E (ApoE), which has been shown to influence serum lipid parameters, can bind to multiple types of lipids and plays an important role in the metabolism and homeostasis of lipids and lipoproteins. A previous study showed that ApoE concentration significantly affects serum lipid levels independently of ApoE polymorphism. The serum lipid levels were also closely correlated with dietary habits, and Shandong cuisine is famous for its high salt and oil contents, which widely differ among the different areas in China. Therefore, studying the effect of ApoE polymorphism on ApoE concentration and serum lipid levels in Shandong province is very important.A total of 815 subjects including 285 men and 530 women were randomly selected and studied from Jinan, Shandong province. In order to evaluate the association of ApoE polymorphism and serum level on lipid profiles, the ApoE genotypes, as well as levels of fasting serum ApoE and other lipid parameters, were detected in all subjects.The frequency of the ApoE E3 allele was highest (83.1%), while those of E2 and E4 were 9.4% and 7.5%, respectively, which are similar to those in other Asian populations. ApoE2 allele carriers showed significantly increased ApoE levels but lower levels of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and Apolipoprotein B (ApoB).We found that ApoE level is influenced by ApoE polymorphism in a gene-dependent manner. The ApoE polymorphism showed different influences on serum lipid parameters with increasing age and body mass index (BMI) in our Shandong Han population.

  6. Serum apolipoprotein E concentration and polymorphism influence serum lipid levels in Chinese Shandong Han population

    PubMed Central

    Han, ShuYi; Xu, YiHui; Gao, MeiHua; Wang, YunShan; Wang, Jun; Liu, YanYan; Wang, Min; Zhang, XiaoQian

    2016-01-01

    Abstract Apolipoprotein E (ApoE), which has been shown to influence serum lipid parameters, can bind to multiple types of lipids and plays an important role in the metabolism and homeostasis of lipids and lipoproteins. A previous study showed that ApoE concentration significantly affects serum lipid levels independently of ApoE polymorphism. The serum lipid levels were also closely correlated with dietary habits, and Shandong cuisine is famous for its high salt and oil contents, which widely differ among the different areas in China. Therefore, studying the effect of ApoE polymorphism on ApoE concentration and serum lipid levels in Shandong province is very important. A total of 815 subjects including 285 men and 530 women were randomly selected and studied from Jinan, Shandong province. In order to evaluate the association of ApoE polymorphism and serum level on lipid profiles, the ApoE genotypes, as well as levels of fasting serum ApoE and other lipid parameters, were detected in all subjects. The frequency of the ApoE E3 allele was highest (83.1%), while those of E2 and E4 were 9.4% and 7.5%, respectively, which are similar to those in other Asian populations. ApoE2 allele carriers showed significantly increased ApoE levels but lower levels of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and Apolipoprotein B (ApoB). We found that ApoE level is influenced by ApoE polymorphism in a gene-dependent manner. The ApoE polymorphism showed different influences on serum lipid parameters with increasing age and body mass index (BMI) in our Shandong Han population. PMID:27977609

  7. Amyloid mediates the association of apolipoprotein E e4 allele to cognitive function in older people

    PubMed Central

    Bennett, D; Schneider, J; Wilson, R; Bienias, J; Berry-Kravis, E; Arnold, S

    2005-01-01

    Background: The neurobiological changes underlying the association of the apolipoprotein E (APOE) e4 allele with level of cognition are poorly understood. Objective: To test the hypothesis that amyloid load can account for (mediate) the association of the APOE e4 allele with level of cognition assessed proximate to death. Methods: There were 44 subjects with clinically diagnosed Alzheimer's disease and 50 without dementia, who had participated in the Religious Orders Study. They underwent determination of APOE allele status, had comprehensive cognitive testing in the last year of life, and brain autopsy at death. The percentage area of cortex occupied by amyloid beta and the density of tau positive neurofibrillary tangles were quantified from six brain regions and averaged to yield summary measures of amyloid load and neurofibrillary tangles. Multiple regression analyses were used to examine whether amyloid load could account for the effect of allele status on level of cognition, controlling for age, sex, and education. Results: Possession of at least one APOE e4 allele was associated with lower level of cognitive function proximate to death (p = 0.04). The effect of the e4 allele was reduced by nearly 60% and was no longer significant after controlling for the effect of amyloid load, whereas there was a robust inverse association between amyloid and cognition (p = 0.001). Because prior work had suggested that neurofibrillary tangles could account for the association of amyloid on cognition, we next examined whether amyloid could account for the effect of allele status on tangles. In a series of regression analyses, e4 was associated with density of tangles (p = 0.002), but the effect of the e4 allele was reduced by more than 50% and was no longer significant after controlling for the effect of amyloid load. Conclusion: These findings are consistent with a sequence of events whereby the e4 allele works through amyloid deposition and subsequent tangle formation to

  8. [Polymorphism of the apolipoprotein E gene (APOE) in the populations of Russia and neighboring countries].

    PubMed

    Borinskaia, S A; Kal'ina, N R; Sanina, E D; Kozhekbaeva, Zh M; Gupalo, E Iu; Garmash, I V; Ogurtsov, P P; Parshukova, O N; Boĭko, S G; Veselovskiĭ, E M; Vershubskaia, G G; Kozlov, A I; Rogaev, E I; Iankovskiĭ, N K

    2007-10-01

    Allele and genotype frequencies for the locus encoding apolipoprotein E, involved in the regulation of lipid metabolism (APOE), were evaluated in 16 populations representing 12 ethnic groups (a total of 1103 subjects) from Russia and neighboring countries. In the populations examined, the frequencies of allele epsilon4, which is the risk factor of Alzheimer's disease and coronary heart disease, varied from less than 5 to more than 20%, while the variation of the major epsilon3 allele in these populations ranged from less than 75 to 95%. The frequencies of alleles epsilon3 and epsilon4 were 0.714 and 0.205 in Saami, 0.734 and 0.149 in Maris, 0.841 and 0.122 in Evenks, 0.788 and 0.163 in Buryats, 0.764 and 0.202 in Chukchi, 0.875 and 0.075 in Iranians, 0.956 and 0.044 in mountain-dwellers of the Pamirs, 0.771 and 0.094 in Ukrainians, and 0.795 and 0.091 in Belarussians, respectively. In Russians from different regions of the country, the frequencies of these alleles were 0.728 and 0.139 (Kostroma), 0.795 and 0.105 (Moscow), 0.857 and 0.092 (Rostov-on-Don), and 0.824 and 0.083 (Krasnodar), respectively. The latitudinal distribution of the APOE epsilon3 and epsilon4 allele frequencies in the populations examined was comparable to the frequency distribution pattern of these alleles in other populations of Eurasia.

  9. Apolipoprotein E metabolism and functions in brain and its role in Alzheimer's disease

    PubMed Central

    Liao, Fan; Yoon, Hyejin; Kim, Jungsu

    2017-01-01

    Purpose of review APOE4 genotype is the strongest genetic risk factor for Alzheimer's disease. Prevailing evidence suggests that amyloid β plays a critical role in Alzheimer's disease. The objective of this article is to review the recent findings about the metabolism of apolipoprotein E (ApoE) and amyloid β and other possible mechanisms by which ApoE contributes to the pathogenesis of Alzheimer's disease. Recent findings ApoE isoforms have differential effects on amyloid β metabolism. Recent studies demonstrated that ApoE-interacting proteins, such as ATP-binding cassette A1 (ABCA1) and LDL receptor, may be promising therapeutic targets for Alzheimer's disease treatment. Activation of liver X receptor and retinoid X receptor pathway induces ABCA1 and other genes, leading to amyloid β clearance. Inhibition of the negative regulators of ABCA1, such as microRNA-33, also induces ABCA1 and decreases the levels of ApoE and amyloid β. In addition, genetic inactivation of an E3 ubiquitin ligase, myosin regulatory light chain interacting protein, increases LDL receptor levels and inhibits amyloid accumulation. Although amyloid β-dependent pathways have been extensively investigated, there have been several recent studies linking ApoE with vascular function, neuroinflammation, metabolism, synaptic plasticity, and transcriptional regulation. For example, ApoE was identified as a ligand for a microglial receptor, TREM2, and studies suggested that ApoE may affect the TREM2-mediated microglial phagocytosis. Summary Emerging data suggest that ApoE affects several amyloid β-independent pathways. These underexplored pathways may provide new insights into Alzheimer's disease pathogenesis. However, it will be important to determine to what extent each mechanism contributes to the pathogenesis of Alzheimer's disease. PMID:27922847

  10. Tau hyperphosphorylation in apolipoprotein E-deficient and control mice after closed head injury.

    PubMed

    Genis, L; Chen, Y; Shohami, E; Michaelson, D M

    2000-05-15

    Apolipoprotein E (apoE)-deficient mice have learning and memory impairments that are associated with specific neurochemical changes and hyperphosphorylation of distinct epitopes of the cytoskeletal protein tau. Furthermore, such mice are highly susceptible to the sequelae of brain trauma and their ability to recover from head injury is impaired. In the present study we investigated the extent that the neuronal maintenance and repair impairments of apoE-deficient mice are related to aberrations at the tau phosphorylation level. This was pursued by subjecting control and apoE-deficient mice to closed head injury (CHI) and examination, utilizing immunoblot assays, of the resulting effects on tau phosphorylation. The results thus obtained revealed that tau of apoE-deficient mice is hyperphosphorylated before CHI and that this insult results in transient tau hyperphosphorylation, whose extent and time course in the two mouse groups varied markedly. Tau hyperphosphorylation in the injured controls was maximal by about 4 hr after injury and reverted to basal levels by 24 hr. In contrast, almost no head injury-induced tau hyperphosphorylation was observed in the apoE-deficient mice at 4 hr after injury. Some tau hyper-phosphorylation was detected in the head-injured apoE-deficient mice after longer time intervals, but its extent was markedly lower than the maximal values obtained in the head injured controls. These findings show that the chronic neuronal impairments brought about by apoE deficiency and the acute response to head injury are both associated with hyperphosphorylation of the same tau domain and that the ability of apoE-deficient mice to mount the acute tau hyperphosphorylation response to head injury is impaired.

  11. Inhibition of Interleukin-10 Signaling Induces Microbiota-Dependent Chronic Colitis in Apolipoprotein E Deficient Mice

    PubMed Central

    Singh, Vishal; Kumar, Manish; Yeoh, Beng San; Xiao, Xia; Saha, Piu; Kennett, Mary J.; Vijay-Kumar, Matam

    2015-01-01

    Background Apolipoprotein E (ApoE) mediates potent anti-inflammatory and immunomodulatory properties in addition to its roles in regulating cholesterol transport and metabolism. However, its role in the intestine, specifically during inflammation is largely unknown. Methods Mice [C57BL/6 or ApoE deficient (ApoE-KO) mice] were administered either single or four injections (weekly) of anti-interleukin (IL)-10 receptor monoclonal antibody (1.0 mg/mouse; intraperitoneally) and euthanized one week after the last injection. 16S rRNA sequencing was performed in fecal samples to analyze the gut bacterial load and its composition. Microbiota was ablated by administration of broad-spectrum antibiotics in drinking water. IL-10KO mice were cohoused with ApoE-KO mice or their WT littermates to monitor the colitogenic potential of gut microbiota harbored in ApoE-KO mice. Results ApoE-KO mice developed severe colitis upon neutralization of IL-10 signaling as assessed by every parameter analyzed. 16S rRNA sequencing revealed that the ApoE-KO mice display elevated and altered gut microbiota that were accompanied with impaired production of intestinal antimicrobial peptides. Interestingly, microbiota ablation ameliorates the colitis development in ApoE-KO mice. Exacerbated and accelerated colitis was observed in IL-10KO mice when cohoused with ApoE-KO mice. Conclusions Our study highlights a novel interplay between ApoE and IL-10 in maintaining gut homeostasis and that such cross-talk may play a critical role in inflammatory bowel disease (IBD) pathogenesis. Gut sterilization and cohousing experiment suggests that microbiota play pivotal role in the development of IBD in mice lacking ApoE. PMID:26891260

  12. Apolipoprotein E4 allele as a predictor of cholinergic deficits and treatment outcome in Alzheimer disease.

    PubMed Central

    Poirier, J; Delisle, M C; Quirion, R; Aubert, I; Farlow, M; Lahiri, D; Hui, S; Bertrand, P; Nalbantoglu, J; Gilfix, B M

    1995-01-01

    Apolipoprotein E (apoE) is critical in the modulation of cholesterol and phospholipid transport between cells of different types. Human apoE is a polymorphic protein with three common alleles, APO epsilon 2, APO epsilon 3, and APO epsilon 4. ApoE4 is associated with sporadic and late-onset familial Alzheimer disease (AD). Gene dose was shown to have an effect on risk of developing AD, age of onset, accumulation of senile plaques in the brain, and reduction of choline acetyltransferase (ChAT) activity in the hippocampus of AD subjects. To characterize the possible impact of the apoE4 allele on cholinergic markers in AD, we examined the effect of apoE4 allele copy number on pre- and postsynaptic markers of cholinergic activity. ApoE4 allele copy number showed an inverse relationship with residual brain ChAT activity and nicotinic receptor binding sites in both the hippocampal formation and the temporal cortex of AD subjects. AD cases lacking the apoE4 allele showed ChAT activities close or within age-matched normal control values. The effect of the apoE4 allele on cholinomimetic drug responsiveness was assessed next in a group (n = 40) of AD patients who completed a double-blind, 30-week clinical trial of the cholinesterase inhibitor tacrine. Results showed that > 80% of apoE4-negative AD patients showed marked improvement after 30 weeks as measured by the AD assessment scale (ADAS), whereas 60% of apoE4 carriers had ADAS scores that were worse compared to baseline. These results strongly support the concept that apoE4 plays a crucial role in the cholinergic dysfunction associated with AD and may be a prognostic indicator of poor response to therapy with acetylcholinesterase inhibitors in AD patients. Images Fig. 2 PMID:8618881

  13. Modulation of autoimmune arthritis severity in mice by apolipoprotein E (ApoE) and cholesterol.

    PubMed

    Alvarez, P; Genre, F; Iglesias, M; Augustin, J J; Tamayo, E; Escolà-Gil, J C; Lavín, B; Blanco-Vaca, F; Merino, R; Merino, J

    2016-12-01

    Apolipoprotein E (ApoE) deficiency promoted an exacerbation of autoimmune arthritis in mice by inducing proinflammatory immune responses. In this study we analysed the contribution of hypercholesterolaemia and/or the absence of ApoE anti-inflammatory properties, unrelated to its function in the control of cholesterol metabolism, towards the acceleration of arthritis in these mutant animals. The induction and severity of collagen type II-induced arthritis (CIA) were compared for B10.RIII wild-type (WT), B10.RIII.ApoE(+/-) , B10.RIII.ApoE(-/-) and B10.RIII.low-density lipoprotein receptor (LDLR(-/-) ) mice with different concentrations of circulating ApoE and cholesterol. A 50-70% reduction in serum levels of ApoE was observed in heterozygous B10.RIII.ApoE(+/-) mice in comparison to B10.RIII.WT, although both strains of mice exhibited similar circulating lipid profiles. This ApoE reduction was associated with an increased CIA severity that remained lower than in homozygous B10.RIII.ApoE(-/-) mice. An important rise in circulating ApoE concentration was observed in hypercholesterolaemic B10.RIII.LDLR(-/-) mice fed with a normal chow diet, and both parameters increased further with an atherogenic hypercholesterolaemic diet. However, the severity of CIA in B10.RIII.LDLR(-/-) mice was similar to that of B10.RIII.WT controls. In conclusion, by comparing the evolution of CIA between several strains of mutant mice with different levels of serum ApoE and cholesterol, our results demonstrate that both hypercholesterolaemia and ApoE regulate the intensity of in-vivo systemic autoimmune responses.

  14. Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of apolipoprotein E deficient mice

    SciTech Connect

    Xiao, Hong-Bo; Lu, Xiang-Yang; Sun, Zhi-Liang; Zhang, Heng-Bo

    2011-12-15

    Recent studies show that osteopontin (OPN) and its receptor cluster of differentiation 44 (CD44) are two pro-inflammatory cytokines contributing to the development of atherosclerosis. The objective of this study was to explore the inhibitory effect of kaempferol, a naturally occurring flavonoid compound, on atherogenesis and the mechanisms involved. The experiments were performed in aorta and plasma from C57BL/6J control and apolipoprotein E-deficient (ApoE{sup -/-}) mice treated or not with kaempferol (50 or 100 mg/kg, intragastrically) for 4 weeks. Kaempferol treatment decreased atherosclerotic lesion area, improved endothelium-dependent vasorelaxation, and increased the maximal relaxation value concomitantly with decrease in the half-maximum effective concentration, plasma OPN level, aortic OPN expression, and aortic CD44 expression in ApoE{sup -/-} mice. In addition, treatment with kaempferol also significantly decreased reactive oxygen species production in mice aorta. The present results suggest that kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of ApoE{sup -/-} mice. -- Graphical abstract: Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis of ApoE{sup -/-} mice. Highlights: Black-Right-Pointing-Pointer OPN-CD44 pathway plays a critical role in the development of atherosclerosis. Black-Right-Pointing-Pointer We examine lesion area, OPN and CD44 changes after kaempferol treatment. Black-Right-Pointing-Pointer Kaempferol treatment decreased atherosclerotic lesion area in ApoE{sup -/-} mice. Black-Right-Pointing-Pointer Kaempferol treatment decreased aortic OPN and CD44 expressions in ApoE{sup -/-} mice. Black-Right-Pointing-Pointer Kaempferol regulates OPN-CD44 pathway to inhibit the atherogenesis.

  15. Induction of fibroblast apolipoprotein E expression during apoptosis, starvation-induced growth arrest and mitosis.

    PubMed Central

    Quinn, Carmel M; Kågedal, Katarina; Terman, Alexei; Stroikin, Uri; Brunk, Ulf T; Jessup, Wendy; Garner, Brett

    2004-01-01

    Apolipoprotein E (apoE) mediates the hepatic clearance of plasma lipoproteins, facilitates cholesterol efflux from macrophages and aids neuronal lipid transport. ApoE is expressed at high levels in hepatocytes, macrophages and astrocytes. In the present study, we identify nuclear and cytosolic pools of apoE in human fibroblasts. Fibroblast apoE mRNA and protein levels were up-regulated during staurosporine-induced apoptosis and this was correlated with increased caspase-3 activity and apoptotic morphological alterations. Because the transcription of apoE and specific pro-apoptotic genes is regulated by the nuclear receptor LXR (liver X receptor) alpha, we analysed LXRalpha mRNA expression by quantitative real-time PCR and found it to be increased before apoE mRNA induction. The expression of ABCA1 (ATP-binding cassette transporter A1) mRNA, which is also regulated by LXRalpha, was increased in parallel with apoE mRNA, indicating that LXRalpha probably promotes apoE and ABCA1 transcription during apoptosis. Fibroblast apoE levels were increased under conditions of serum-starvation-induced growth arrest and hyperoxia-induced senescence. In both cases, an increased nuclear apoE level was observed, particularly in cells that accumulated lipofuscin. Nuclear apoE was translocated to the cytosol when mitotic nuclear disassembly occurred and this was associated with an increase in total cellular apoE levels. ApoE amino acid sequence analysis indicated several potential sites for phosphorylation. In vivo studies, using 32P-labelling and immunoprecipitation, revealed that fibroblast apoE can be phosphorylated. These studies reveal novel associations and potential roles for apoE in fundamental cellular processes. PMID:14656220

  16. Blue-Green Algae Inhibit the Development of Atherosclerotic Lesions in Apolipoprotein E Knockout Mice

    PubMed Central

    Ku, Chai Siah; Kim, Bohkyung; Pham, Tho X.; Yang, Yue; Wegner, Casey J.; Park, Young-Ki; Balunas, Marcy

    2015-01-01

    Abstract Hyperlipidemia and inflammation contribute to the development of atherosclerotic lesions. Our objective was to determine antiatherogenic effect of edible blue-green algae (BGA) species, that is, Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP), in apolipoprotein E knockout (ApoE−/−) mice, a well-established mouse model of atherosclerosis. Male ApoE−/− mice were fed a high-fat/high-cholesterol (HF/HC, 15% fat and 0.2% cholesterol by wt) control diet or a HF/HC diet supplemented with 5% (w/w) of NO or SP powder for 12 weeks. Plasma total cholesterol (TC) and triglycerides (TG) were measured, and livers were analyzed for histology and gene expression. Morphometric analysis for lesions and immunohistochemical analysis for CD68 were conducted in the aorta and the aortic root. NO supplementation significantly decreased plasma TC and TG, and liver TC, compared to control and SP groups. In the livers of NO-fed mice, less lipid droplets were present with a concomitant decrease in fatty acid synthase protein levels than the other groups. There was a significant increase in hepatic low-density lipoprotein receptor protein levels in SP-supplemented mice than in control and NO groups. Quantification of aortic lesions by en face analysis demonstrated that both NO and SP decreased aortic lesion development to a similar degree compared with control. While lesions in the aortic root were not significantly different between groups, the CD68-stained area in the aortic root was significantly lowered in BGA-fed mice than controls. In conclusion, both NO and SP supplementation decreased the development of atherosclerotic lesions, suggesting that they may be used as a natural product for atheroprotection. PMID:26566121

  17. Apolipoprotein E and Alzheimer disease: Genotype-specific risks by age and sex

    SciTech Connect

    Bickeboeller, H. |; Babron, M.C.; Clerget-Darpoux, F.

    1997-02-01

    The distribution of apolipoprotein E (APOE) genotypes as a function of age and sex has been examined in a French population of 417 Alzheimer disease (AD) patients and 1,030 control subjects. When compared to the APOE {epsilon}3 allele, an increased risk associated with the APOE {epsilon}4 allele (odds ratio [OR] [{epsilon}4] = 2.7 with 95% confidence interval [CI] = 2.0-3.6; P < .001) and a protective effect of the APOE {epsilon}2 allele (OR[{epsilon}2] = 0.5 with 95% CI = 0.3-0.98; P = .012) were retrieved. An effect of the {epsilon}4 allele dosage on susceptibility was confirmed (OR[{epsilon}4/{epsilon}4] vs. the {epsilon}3/{epsilon}3 genotype = 11.2 [95% CI = 4.0-31.6]; OR[{epsilon}3/{epsilon}4] vs. the {epsilon}3/{epsilon}3 genotype = 2.2 [95% Cl = 1.5-3.5]). The frequency of the {epsilon}4 allele was lower in male cases than in female cases, but, since a similar difference was found in controls, this does not lead to a difference in OR between sex. ORs for the {epsilon}4 allele versus the {epsilon}3 allele, OR({epsilon}4), were not equal in all age classes: OR({epsilon}4) in the extreme groups with onset at < 60 years or > 79 years were significantly lower than those from the age groups 60-79 years. In {epsilon}3/{epsilon}4 individuals, sex-specific lifetime risk estimates by age 85 years (i.e., sex-specific penetrances by age 85 years) were 0.14 (95% CI 0.04-0.30) for men and 0.17 (95% CI 0.09-0.28) for women. 53 refs., 1 fig., 3 tabs.

  18. Apolipoprotein E gene polymorphism and Alzheimer's disease in Chinese population: a meta-analysis

    NASA Astrophysics Data System (ADS)

    Liu, Mengying; Bian, Chen; Zhang, Jiqiang; Wen, Feng

    2014-03-01

    The relationship between Apolipoprotein E (ApoE) genotype and the risk of Alzheimer's disease (AD) is relatively well established in Caucasians, but less established in other ethnicities. To examine the association between ApoE polymorphism and the onset of AD in Chinese population, we searched the commonly used electronic databases between January 2000 and November 2013 for relevant studies. Total 20 studies, including 1576 cases and 1741 controls, were retrieved. The results showed statistically significant positive association between risk factor ɛ4 allele carriers and AD in Chinese population (OR = 3.93, 95% CI = 3.37-4.58, P < 0.00001). Genotype ApoE ɛ4/ɛ4 and ɛ4/ɛ3 have statistically significant association with AD as well (ɛ4/ɛ4: OR = 11.76, 95% CI = 6.38-21.47, P < 0.00001; ɛ4/ɛ3: OR = 3.08, 95% CI = 2.57-3.69, P < 0.00001). Furthermore, the frequency of the ApoE ɛ3 is lower in AD than that in the health controls, and the difference of ɛ3 allele is also statistically significant (OR = 0.42, 95% CI = 0.37-0.47, P < 0.00001). No significant heterogeneity was observed among all studies. This meta-analysis suggests that the subject with at least one ApoE ɛ4 allele has higher risk suffering from AD than controls in Chinese population. The results also provide a support for the protection effect of ApoE ɛ3 allele in developing AD.

  19. Apolipoprotein E epsilon4 allele differentiates the clinical response to donepezil in Alzheimer's disease.

    PubMed

    Bizzarro, A; Marra, C; Acciarri, A; Valenza, A; Tiziano, F D; Brahe, C; Masullo, C

    2005-01-01

    The existence of an association between apolipoprotein E (APOE) and Alzheimer's disease (AD) has been reported in several studies. The possession of an ApoE epsilon4 allele is now considered a genetic risk factor for sporadic AD. There has been a growing agreement about the role exerted by the ApoE epsilon4 allele on the neuropsychological profile and the rate of cognitive decline in AD patients. However, a more controversial issue remains about a possible influence of the APOE genotype on acetylcholinesterase inhibitor therapy response in AD patients. In order to address this issue, 81 patients diagnosed as having probable AD were evaluated by a complete neuropsychological test battery at the time of diagnosis (baseline) and after 12-16 months (retest). Patients were divided into two subgroups: (1) treated with donepezil at a dose of 5 mg once a day (n = 41) and (2) untreated (n = 40). Donepezil therapy was started after baseline evaluation. The APOE genotype was determined according to standardized procedures. We evaluated the possible effect of the APOE genotype on the neuropsychological tasks in relation to donepezil therapy. The statistical analysis of the results showed a global worsening of cognitive performances for all AD patients at the retest. Differences in the clinical outcome were analysed in the four subgroups of AD patients for each neuropsychological task. ApoE epsilon4 carriers/treated patients had improved or unchanged scores at retest evaluation for the following tasks: visual and verbal memory, visual attention and inductive reasoning and Mini Mental State Examination. These results indicate an effect of donepezil on specific cognitive domains (attention and memory) in the ApoE epsilon4 carriers with AD. This might suggest an early identification of AD patients carrying at least one epsilon4 allele as responders to donepezil therapy.

  20. Differential action of glucocorticoids on apolipoprotein E gene expression in macrophages and hepatocytes

    PubMed Central

    Trusca, Violeta Georgeta; Fuior, Elena Valeria; Fenyo, Ioana Madalina; Kardassis, Dimitris; Simionescu, Maya

    2017-01-01

    Apolipoprotein E (apoE) has anti-atherosclerotic properties, being involved in the transport and clearance of cholesterol-rich lipoproteins as well as in cholesterol efflux from cells. We hypothesized that glucocorticoids may exert anti-inflammatory properties by increasing the level of macrophage-derived apoE. Our data showed that glucocorticoids increased apoE expression in macrophages in vitro as well as in vivo. Dexamethasone increased ~6 fold apoE mRNA levels in cultured peritoneal macrophages and RAW 264.7 cells. Administered to C57BL/6J mice, dexamethasone induced a two-fold increase in apoE expression in peritoneal macrophages. By contrast, glucocorticoids did not influence apoE expression in hepatocytes, in vitro and in vivo. Moreover, dexamethasone enhanced apoE promoter transcriptional activity in RAW 264.7 macrophages, but not in HepG2 cells, as tested by transient transfections. Analysis of apoE proximal promoter deletion mutants, complemented by protein-DNA interaction assays demonstrated the functionality of a putative glucocorticoid receptors (GR) binding site predicted by in silico analysis in the -111/-104 region of the human apoE promoter. In hepatocytes, GR can bind to their specific site within apoE promoter but are not able to modulate the gene expression. The modulatory blockade in hepatocytes is a consequence of partial involvement of transcription factors and other signaling molecules activated through MEK1/2 and PLA2/PLC pathways. In conclusion, our study indicates that glucocorticoids (1) differentially target apoE gene expression; (2) induce a significant increase in apoE level specifically in macrophages. The local increase of apoE gene expression in macrophages at the level of the atheromatous plaque may have therapeutic implications in atherosclerosis. PMID:28355284

  1. Anti-atherogenic effect of Humulus japonicus in apolipoprotein E-deficient mice

    PubMed Central

    Lim, Haian; Noh, Jung-Ran; Kim, Yong-Hoon; Hwang, Jung Hwan; Kim, Kyoung-Shim; Choi, Dong-Hee; Go, Min-Jeong; Han, Sang-Seop; Oh, Won-Keun; Lee, Chul-Ho

    2016-01-01

    Humulus japonicus (HJ) is used as a traditional medicine in Korea owing to its multiple properties including anti-mycobacterial, antioxidant and antihypertensive effects. The present study aimed to examine the anti-inflammatory and anti-atherogenic effects of a methanol extract of HJ. In lipopolysaccharide-stimulated RAW 264.7 cells, HJ significantly suppressed the mRNA expression and secretion of pro-inflammatory cytokines [tumor necrosis factor-α, interleukin (IL)-1β and IL-6)], and the release of inflammatory mediators such as nitrite and prostaglandin E2, together with a concomitant decrease in the mRNA levels of inducible nitric oxide synthase and cyclooxygenase-2. To examine whether HJ is capable of inhibiting experimental atherogenesis in an animal model, we randomly divided apolipoprotein E-deficient (apoE−/−) mice into three groups: mice fed an atherogenic diet plus vehicle (0.5% carboxymethyl cellulose) as the control vehicle group, and mice fed an atherogenic diet plus either 100 (HJ100) or 500 mg/kg (HJ500) of HJ as the experimental groups. After 12 weeks of HJ administration, lipid accumulation and the formation of atherosclerotic lesions in the aorta (en face) and the aortic sinus markedly decreased in the HJ500 group compared with the corresponding values in the vehicle control group. Moreover, monocyte and macrophage infiltration in the aortic sinus was markedly reduced in the HJ500 group. Reverse transcription-quantitative polymerase chain reaction analysis of the whole aorta showed that the mRNA levels of intercellular adhesion molecule-1, monocyte chemoattractant protein-1, CD68 and IL-18 were significantly decreased in the HJ500 group. Collectively, these findings suggest that HJ may suppress atherosclerosis by inhibiting lipid accumulation and the expression of pro-atherogenic factors, and it may be effective at preventing the development of atherosclerosis. PMID:27600281

  2. Apolipoprotein E gene associations in age-related macular degeneration: the Melbourne Collaborative Cohort Study.

    PubMed

    Adams, Madeleine K M; Simpson, Julie A; Richardson, Andrea J; English, Dallas R; Aung, Khin Zaw; Makeyeva, Galina A; Guymer, Robyn H; Giles, Graham G; Hopper, John; Robman, Liubov D; Baird, Paul N

    2012-03-15

    The apolipoprotein E gene (APOE) has been found to be associated with age-related macular degeneration (AMD). Reported associations have been questioned, as they are opposite those for Alzheimer's disease and cardiovascular disease. The authors examined associations between APOE genotype and AMD using a case-control study (2,287 cases and 2,287 controls individually matched on age, sex, and country of origin) nested within Melbourne Collaborative Cohort Study participants aged 48-86 years at AMD detection. The odds ratio for early AMD among participants with ε2-containing genotypes (ε2ε2/ε2ε3/ε2ε4) was 1.32 (95% confidence interval (CI): 1.11, 1.58; P = 0.002) versus persons with genotype ε3ε3. Associations with early AMD varied by smoking status; ε2-containing genotypes were positively associated with early AMD for never and previous smokers (never smokers: odds ratio (OR) = 1.40, 95% CI: 1.12, 1.76 (P = 0.003); previous smokers: OR = 1.39, 95% CI: 1.00, 1.93 (P = 0.05)) but not for current smokers (OR = 0.66, 95% CI: 0.34, 1.30 (P = 0.2; interaction P = 0.05). The ε4-containing genotype group (ε3ε4/ε4ε4) had an inverse association with early AMD among current smokers only (OR = 0.41, 95% CI: 0.22, 0.77 (P = 0.005)). These results highlight the importance of stratifying by smoking status in elderly populations. Smokers who survive to old age may be more likely to possess unknown genotypes which modify exposure-disease associations.

  3. Endothelial Surface Layer Degradation by Chronic Hyaluronidase Infusion Induces Proteinuria in Apolipoprotein E-Deficient Mice

    PubMed Central

    Kuikhoven, Mayella; Heeneman, Sylvia; Lutgens, Esther; Gijbels, Marion J. J.; Nieuwdorp, Max; Peutz, Carine J.; Stroes, Erik S. G.; Vink, Hans; van den Berg, Bernard M.

    2010-01-01

    Objective Functional studies show that disruption of endothelial surface layer (ESL) is accompanied by enhanced sensitivity of the vasculature towards atherogenic stimuli. However, relevance of ESL disruption as causal mechanism for vascular dysfunction remains to be demonstrated. We examined if loss of ESL through enzymatic degradation would affect vascular barrier properties in an atherogenic model. Methods Eight week old male apolipoprotein E deficient mice on Western-type diet for 10 weeks received continuous active or heat-inactivated hyaluronidase (10 U/hr, i.v.) through an osmotic minipump during 4 weeks. Blood chemistry and anatomic changes in both macrovasculature and kidneys were examined. Results Infusion with active hyaluronidase resulted in decreased ESL (0.32±0.22 mL) and plasma volume (1.03±0.18 mL) compared to inactivated hyaluronidase (0.52±0.29 mL and 1.28±0.08 mL, p<0.05 respectively).Active hyaluronidase increased proteinuria compared to inactive hyaluronidase (0.27±0.02 vs. 0.15±0.01 µg/µg protein/creatinin, p<0.05) without changes in glomerular morphology or development of tubulo-interstitial inflammation. Atherosclerotic lesions in the aortic branches showed increased matrix production (collagen, 32±5 vs. 18±3%; glycosaminoglycans, 11±5 vs. 0.1±0.01%, active vs. inactive hyaluronidase, p<0.05). Conclusion ESL degradation in apoE deficient mice contributes to reduced increased urinary protein excretion without significant changes in renal morphology. Second, the induction of compositional changes in atherogenic plaques by hyaluronidase point towards increased plaque vulnerability. These findings support further efforts to evaluate whether ESL restoration is a valuable target to prevent (micro) vascular disease progression. PMID:21170388

  4. Health-protective and Adverse Effects of the Apolipoprotein E ε2 Allele in Older Males

    PubMed Central

    Kulminski, Alexander M.; Ukraintseva, Svetlana V.; Arbeev, Konstantin G.; Manton, Kenneth G.; Oshima, Junko; Martin, George M.; Il'yasova, Dora; Yashin, Anatoli I.

    2009-01-01

    OBJECTIVES: To re-examine a health-protective role of the common Apolipoprotein E (APOE) polymorphism focusing on connections between the APOE ε2-containing genotypes and impairments in instrumental activities of daily living [IADL] in older (65+) males and females. To examine how these connections may be mediated by diagnosed coronary heart disease (CHD), Alzheimer's disease, colorectal cancer, macular degeneration (MD), and atherosclerosis. DESIGN: Retrospective cross-sectional study. SETTING: The unique disability-focused data from a genetic sub-sample of the 1999 National Long Term Care Survey linked with Medicare service use files. PARTICIPANTS: 1733 genotyped individuals interviewed on IADL disabilities. MEASUREMENTS: Indicators of IADL impairments, five geriatric disorders, and ε2-containing genotypes. RESULTS: The ε2/3 genotype is a major contributor to adverse associations between the ε2 allele and IADL disability in males [Odds Ratio (OR)=3.09, Confidence Interval (CI)=1.53-6.26)]. It shows, however, significant protective effects for CHD (OR=0.55, CI=0.33-0.92), while CHD is adversely associated with IADL disability (OR=2.18, CI=1.28-3.72). The presence of five diseases does not significantly alter the adverse association between ε2-containing genotypes and disability. Protective effects of the ε2/3 genotype for CHD (OR=0.52, CI=0.27-0.99) and deleterious effects for IADL (OR=3.50, CI=1.71-7.14) for males hold in multivariate models with both these factors included. No significant associations between the ε2-containing genotypes and IADL are found in females. CONCLUSIONS: The ε2 allele can play a dual role in males, protecting them against some health disorders, while promoting others. Strong adverse relationships with disability suggest that ε2-containing genotypes can be unfavorable factors for the health/well-being of aging males. PMID:18179501

  5. A Multinuclear Copper(I) Cluster Forms the Dimerization Interface in Copper-Loaded Human Copper Chaperone for Superoxide Dismutase

    SciTech Connect

    Stasser, J.P.; Siluvai, G.S.; Barry, A.N.; Blackburn, N.J.

    2009-06-04

    Copper binding and X-ray aborption spectroscopy studies are reported on untagged human CCS (hCCS; CCS = copper chaperone for superoxide dismutase) isolated using an intein self-cleaving vector and on single and double Cys to Ala mutants of the hCCS MTCQSC and CSC motifs of domains 1 (D1) and 3 (D3), respectively. The results on the wild-type protein confirmed earlier findings on the CCS-MBP (maltose binding protein) constructs, namely, that Cu(I) coordinates to the CXC motif, forming a cluster at the interface of two D3 polypeptides. In contrast to the single Cys to Ser mutations of the CCS-MBP protein (Stasser, J. P., Eisses, J. F., Barry, A. N., Kaplan, J. H., and Blackburn, N. J. (2005) Biochemistry 44, 3143-3152), single Cys to Ala mutations in D3 were sufficient to eliminate cluster formation and significantly reduce CCS activity. Analysis of the intensity of the Cu-Cu cluster interaction in C244A, C246A, and C244/246A variants suggested that the nuclearity of the cluster was greater than 2 and was most consistent with a Cu4S6 adamantane-type species. The relationship among cluster formation, oligomerization, and metal loading was evaluated. The results support a model in which Cu(I) binding converts the apo dimer with a D2-D2 interface to a new dimer connected by cluster formation at two D3 CSC motifs. The predominance of dimer over tetramer in the cluster-containing species strongly suggests that the D2 dimer interface remains open and available for sequestering an SOD1 monomer. This work implicates the copper cluster in the reactive form and adds detail to the cluster nuclearity and how copper loading affects the oligomerization states and reactivity of CCS for its partner SOD1.

  6. Can gallium dimer react effectively with three H 2 molecules to form digallane?

    NASA Astrophysics Data System (ADS)

    Moc, Jerzy

    2005-06-01

    Distinct routes of formation of digallane (4) Ga 2H 4 and digallane (6) Ga 2H 6 starting with gallium atoms/H 2 and gallium dimers/H 2 are compared based on the high level ab initio single-reference CCSD(T) and CASSCF based SOCI and hybrid density functional theory calculations of the mechanisms involved. The predicted reaction paths are of relevance to the recent matrix IR studies on the gallium hydrides, notably the extensive one by Wang and Andrews [X. Wang, L. Andrews, J. Phys. Chem. A 107 (2003) 11371] who isolated and assigned the series of mono- and digallium hydrides including the two digallanes.

  7. Sirt1 is involved in decreased bone formation in aged apolipoprotein E-deficient mice

    PubMed Central

    Hong, Wei; Xu, Xiao-ya; Qiu, Zhao-hui; Gao, Jian-jun; Wei, Zhan-ying; Zhen, Li; Zhang, Xiao-li; Ye, Zhi-bing

    2015-01-01

    Aim: Apolipoprotein E (ApoE) plays an important role in the transport and metabolism of lipids. Recent studies show that bone mass is increased in young apoE−/− mice. In this study we investigated the bone phenotype and metabolism in aged apoE−/− mice. Methods: Femurs and tibias were collected from 18- and 72-week-old apoE−/− mice and their age-matched wild-type (WT) littermates, and examined using micro-CT and histological analysis. Serum levels of total cholesterol, oxidized low-density lipoprotein (ox-LDL) and bone turnover markers were measured. Cultured bone mesenchymal stem cells (BMSCs) from tibias and femurs of 18-week-old apoE−/− mice were used in experiments in vitro. The expression levels of Sirt1 and Runx2 in bone tissue and BMSCs were measured using RT-PCR and Western blot analysis. Results: Compared with age-matched WT littermates, young apoE−/− mice exhibited high bone mass with increased bone formation, accompanied by higher serum levels of bone turnover markers OCN and TRAP5b, and higher expression levels of Sirt1, Runx2, ALP and OCN in bone tissue. In contrast, aged apoE−/− mice showed reduced bone formation and lower bone mass relative to age-matched WT mice, accompanied by lower serum OCN levels, and markedly reduced expression levels of Sirt1, Runx2, ALP and OCN in bone tissue. After BMSCs were exposed to ox-LDL (20 μg/mL), the expression of Sirt1 and Runx2 proteins was significantly increased at 12 h, and then decreased at 72 h. Treatment with the Sirt1 inhibitor EX527 (10 μmol/L) suppressed the expression of Runx2, ALP and OCN in BMSCs. Conclusion: In contrast to young apoE−/− mice, aged apoE−/− mice showe lower bone mass than age-matched WT mice. Long-lasting exposure to ox-LDL decreases the expression of Sirt1 and Runx2 in BMSCs, which may explain the decreased bone formation in aged apoE−/− mice. PMID:26592520

  8. Sequence Diversity and Large-Scale Typing of SNPs in the Human Apolipoprotein E Gene

    PubMed Central

    Nickerson, Deborah A.; Taylor, Scott L.; Fullerton, Stephanie M.; Weiss, Kenneth M.; Clark, Andrew G.; Stengård, Jari H.; Salomaa, Veikko; Boerwinkle, Eric; Sing, Charles F.

    2000-01-01

    A common strategy for genotyping large samples begins with the characterization of human single nucleotide polymorphisms (SNPs) by sequencing candidate regions in a small sample for SNP discovery. This is usually followed by typing in a large sample those sites observed to vary in a smaller sample. We present results from a systematic investigation of variation at the human apolipoprotein E locus (APOE), as well as the evaluation of the two-tiered sampling strategy based on these data. We sequenced 5.5 kb spanning the entire APOE genomic region in a core sample of 72 individuals, including 24 each of African-Americans from Jackson, Mississippi; European-Americans from Rochester, Minnesota; and Europeans from North Karelia, Finland. This sequence survey detected 21 SNPs and 1 multiallelic indel, 14 of which had not been previously reported. Alleles varied in relative frequency among the populations, and 10 sites were polymorphic in only a single population sample. Oligonucleotide ligation assays (OLA) were developed for 20 of these sites (omitting the indel and a closely-linked SNP). These were then scored in 2179 individuals sampled from the same three populations (n = 843, 884, and 452, respectively). Relative allele frequencies were generally consistent with estimates from the core sample, although variation was found in some populations in the larger sample at SNPs that were monomorphic in the corresponding smaller core sample. Site variation in the larger samples showed no systematic deviation from Hardy-Weinberg expectation. The large OLA sample clearly showed that variation in many, but not all, of OLA-typed SNPs is significantly correlated with the classical protein-coding variants, implying that there may be important substructure within the classical ɛ2, ɛ3, and ɛ4 alleles. Comparison of the levels and patterns of polymorphism in the core samples with those estimated for the OLA-typed samples shows how nucleotide diversity is underestimated when

  9. Apolipoprotein E genotyping and cerebrospinal fluid tau protein: implications for the clinical diagnosis of Alzheimer's disease.

    PubMed

    Arai, H; Higuchi, S; Sasaki, H

    1997-01-01

    Apolipoprotein E (ApoE) genotyping was conducted in sporadic Alzheimer's disease (AD, n = 91) as well as in other dementing disorders including Parkinson's disease (PD, n = 73), autopsy-confirmed diffuse Lewy body disease (DLBD, n = 16), progressive supranuclear palsy (n = 13), vascular dementia (n = 55), alcoholic dementia (n =25) and normal control subjects (n = 77). ApoE epsilon 4 allele frequency was significantly higher in AD (33.5%, p < 0.001), DLBD (40.6%, p < 0.001) and demented PD (29.4%, p < 0.05) compared to that in normal controls (11.7%). The association of the ApoE epsilon 4 allele with AD was more pronounced in early-onset AD (46.4%) than in late-onset AD (27.8%). 46% of the AD individuals developed AD without association to ApoE epsilon 4, and epsilon 4 homozygotes were found not only in AD, but also in many of other dementing disorders. These results suggest that ApoE genotyping cannot provide certainty about the presence of absence of AD, and that it should be used as an adjunct to other diagnostic tests for AD. On the other hand, cerebrospinal fluid (CSF) tau levels were significantly elevated (p < 0.0001) in AD (78.0 +/- 44.2 pg/ml) compared to those in normal controls (10.6 +/- 8.6 pg/ml). The specificity and the sensitivity of distinguishing AD from normal controls was 95.0 and 91.2%, respectively. Elevated CSF-tau levels were also detected in some patients with acute neurological diseases including meningoencephalitis, Creutzfeld-Jacob disease, normal pressure hydrocephalus and vitamin B12 deficiency encephalopathy. Increased CSF-tau levels in AD were found regardless of the age at onset, clinical stage, ApoE genotype, alpha 1-antichymotrypsin genotype, and presenilin-1 genotype. The CSF-tau levels continued to be abnormal during the progression of AD. These results suggest that CSF-tau serves as an unequivocal and reliable biological marker to aid in the clinical diagnosis of AD.

  10. Identification of a Chrysanthemic Ester as an Apolipoprotein E Inducer in Astrocytes

    PubMed Central

    Zhao, Wenchen; Shimizu, Yoko; Pfeifer, Tom A.; Tak, Jun-Hyung; Isman, Murray B.; Van den Hoven, Bernard; Duggan, Mark E.; Wood, Michael W.; Wellington, Cheryl L.

    2016-01-01

    The apolipoprotein E (APOE) gene is the most highly associated susceptibility locus for late onset Alzheimer’s Disease (AD), and augmenting the beneficial physiological functions of apoE is a proposed therapeutic strategy. In a high throughput phenotypic screen for small molecules that enhance apoE secretion from human CCF-STTG1 astrocytoma cells, we show the chrysanthemic ester 82879 robustly increases expressed apoE up to 9.4-fold and secreted apoE up to 6-fold and is associated with increased total cholesterol in conditioned media. Compound 82879 is unique as structural analogues, including pyrethroid esters, show no effect on apoE expression or secretion. 82879 also stimulates liver x receptor (LXR) target genes including ATP binding cassette A1 (ABCA1), LXRα and inducible degrader of low density lipoprotein receptor (IDOL) at both mRNA and protein levels. In particular, the lipid transporter ABCA1 was increased by up to 10.6-fold upon 82879 treatment. The findings from CCF-STTG1 cells were confirmed in primary human astrocytes from three donors, where increased apoE and ABCA1 was observed along with elevated secretion of high-density lipoprotein (HDL)-like apoE particles. Nuclear receptor transactivation assays revealed modest direct LXR agonism by compound 82879, yet 10 μM of 82879 significantly upregulated apoE mRNA in mouse embryonic fibroblasts (MEFs) depleted of both LXRα and LXRβ, demonstrating that 82879 can also induce apoE expression independent of LXR transactivation. By contrast, deletion of LXRs in MEFs completely blocked mRNA changes in ABCA1 even at 10 μM of 82879, indicating the ability of 82879 to stimulate ABCA1 expression is entirely dependent on LXR transactivation. Taken together, compound 82879 is a novel chrysanthemic ester capable of modulating apoE secretion as well as apoE-associated lipid metabolic pathways in astrocytes, which is structurally and mechanistically distinct from known LXR agonists. PMID:27598782

  11. Alanyl-glutamine attenuates 5-fluorouracil-induced intestinal mucositis in apolipoprotein E-deficient mice

    PubMed Central

    Araújo, C.V.; Lazzarotto, C.R.; Aquino, C.C.; Figueiredo, I.L.; Costa, T.B.; de Oliveira Alves, L.A.; Ribeiro, R.A.; Bertolini, L.R.; Lima, A.A.M.; Brito, G.A.C.; Oriá, R.B.

    2015-01-01

    Apolipoprotein E (APOE=gene, apoE=protein) is a known factor regulating the inflammatory response that may have regenerative effects during tissue recovery from injury. We investigated whether apoE deficiency reduces the healing effect of alanyl-glutamine (Ala-Gln) treatment, a recognized gut-trophic nutrient, during tissue recovery after 5-FU-induced intestinal mucositis. APOE-knockout (APOE-/-) and wild-type (APOE+/+) C57BL6J male and female mice (N=86) were given either Ala-Gln (100 mM) or phosphate buffered saline (PBS) by gavage 3 days before and 5 days after a 5-fluorouracil (5-FU) challenge (450 mg/kg, via intraperitoneal injection). Mouse body weight was monitored daily. The 5-FU cytotoxic effect was evaluated by leukometry. Intestinal villus height, villus/crypt ratio, and villin expression were monitored to assess recovery of the intestinal absorptive surface area. Crypt length, mitotic, apoptotic, and necrotic crypt indexes, and quantitative real-time PCR for insulin-like growth factor-1 (IGF-1) and B-cell lymphoma 2 (Bcl-2) intestinal mRNA transcripts were used to evaluate intestinal epithelial cell turnover. 5-FU challenge caused significant weight loss and leukopenia (P<0.001) in both mouse strains, which was not improved by Ala-Gln. Villus blunting, crypt hyperplasia, and reduced villus/crypt ratio (P<0.05) were found in all 5-FU-challenged mice but not in PBS controls. Ala-Gln improved villus/crypt ratio, crypt length and mitotic index in all challenged mice, compared with PBS controls. Ala-Gln improved villus height only in APOE-/- mice. Crypt cell apoptosis and necrotic scores were increased in all mice challenged by 5-FU, compared with untreated controls. Those scores were significantly lower in Ala-Gln-treated APOE+/+ mice than in controls. Bcl-2 and IGF-1 mRNA transcripts were reduced only in the APOE-/--challenged mice. Altogether our findings suggest APOE-independent Ala-Gln regenerative effects after 5-FU challenge. PMID:25945744

  12. The Association Between Apolipoprotein E and Functional Outcome After Traumatic Brain Injury: A Meta-Analysis.

    PubMed

    Li, Lizhuo; Bao, Yijun; He, Songbai; Wang, Gang; Guan, Yanlei; Ma, Dexuan; Wu, Rile; Wang, Pengfei; Huang, Xiaolong; Tao, Shanwei; Liu, Qiwen; Wang, Yunjie; Yang, Jingyun

    2015-11-01

    Traumatic brain injury (TBI) is a leading cause of death and disability. Previous studies have investigated the association of apolipoprotein E (APOE) ε4 with functional outcome after TBI and reported inconsistent results.The purpose of this study was to perform a systematic literature search and conduct meta-analyses to examine whether APOE ε4 is associated with poorer functional outcome in patients with TBI.We performed a systematic literature search in PubMed, Cochrane Library, Embase, Google Scholar, and HuGE.The eligibility criteria of this study included the following: Patients had TBI; the studies reported APOE genotype data or provided odds ratios (ORs) and the corresponding 95% confidence intervals (CIs); the functional outcome was assessed using the Glasgow Outcome Scale (GOS) or the Glasgow Outcome Scale Extended (GOSE); and patients were followed for at least 3 months after TBI.In all meta-analyses, we used random-effects models to calculate the odds ratio as a measure of association. We examined the association of APOE ε4 with functional outcome at different time points after TBI.A total of 12 studies met the eligibility criteria and were included in the meta-analyses. We did not find a significant association between APOE ε4 and functional outcome at 6 (P = 0.23), 12 (P = 0.44), and 24 months (P = 0.85) after TBI. However, APOE ε4 was associated with an increased risk of unfavorable long-term (≥6 months) functional outcome after TBI (OR = 1.36, 95% CI: 1.07-1.74, P = 0.01).Limitations of this study include The sample size was limited; the initial severity of TBI varied within and across studies; we could not control for potential confounding factors, such as age at injury and sex; a meta-analysis of the genotype dosage effect was not feasible; and we could not examine the association with specific factors such as neurobehavioral or specific cognitive functions.Our meta-analysis indicates APOE ε4 is associated with the long

  13. Crystal Structure of the Mycoplasma arthritidis-Derived Mitogen in Apo Form Reveals a 3D Domain-Swapped Dimer

    SciTech Connect

    Liu, L.; Li, Z; Guo, Y; VanVranken, S; Mourad, W; Li, H

    2010-01-01

    Mycoplasma arthritidis-derived mitogen (MAM) is a superantigen that can activate large fractions of T cells bearing particular V{beta} elements of T cell receptor. Here, we report the crystal structure of a MAM mutant K201A in apo form (unliganded) at 2.8-{angstrom} resolutions. We also partially refined the crystal structures of the MAM wild type and another MAM mutant L50A in apo forms at low resolutions. Unexpectedly, the structures of these apo MAM molecules display a three-dimensional domain-swapped dimer. The entire C-terminal domains of these MAM molecules are involved in the domain swapping. Functional analyses demonstrated that the K201A and L50A mutants do not show altered ability to bind to their host receptors and that they stimulate the activation of T cells as efficiently as does the wild type. Structural comparisons indicated that the 'reconstituted' MAM monomer from the domain-swapped dimer displays large differences at the hinge regions from the MAM{sub wt} molecule in the receptor-bound form. Further comparison indicated that MAM has a flexible N-terminal loop, implying that conformational changes could occur upon receptor binding.

  14. Systemic markers of the redox balance and apolipoprotein E polymorphism in atherosclerosis: the relevance for an integrated study.

    PubMed

    Lopes, Paula A; Napoleão, Patrícia; Pinheiro, Teresa; Ceia, Fátima; Steghens, Jean-Paul; Pavão, M Leoner; Santos, M Cristina; Viegas-Crespo, Ana M

    2006-07-01

    Prospective studies have demonstrated that an imbalance between oxidative damage and antioxidative protection can play a role in the development and progression of atherosclerosis. Also, genotypes with the apolipoprotein E epsilon4 allele have been associated with an increase risk for this pathology. Based on this knowledge, the aim of this study was to evaluate indicators of the redox balance, trace elements, and apolipoprotein E allelic profile in subjects from the Lisbon population with clinically stable atherosclerosis, at risk for atherosclerotic events, and in healthy subjects for comparison. The activities of superoxide dismutase in erythrocytes and glutathione peroxidase in whole blood, plasma total thiols, and serum ceruloplasmin were kept unchanged among the three groups. Serum alpha- tocopherol was increased in atherosclerotic patients. Total malondialdehyde in serum and protein carbonyls in plasma, which are indicators of lipid and protein oxidative damage, respectively, reached their highest values in risk subjects. The concentrations of potassium and calcium, in plasma and in blood cells, were slightly elevated in patients and might reflect an electrolytic imbalance. Regarding the apolipoprotein E polymorphism, atherosclerotic patients had an increased incidence of the high-risk genotypes for atherogenesis (epsilon3/epsilon4 and epsilon4/epsilon4). A multivariate model applied to the general population using most of the parameters clearly separated the three groups at study (i.e., the healthy group from the steady-state group of risk disease and from the atherosclerotic one). As shown by us, the usefulness of biochemical and complementary genetic markers is warranted for a better knowledge on atherosclerosis molecular basis.

  15. [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.

  16. Evidence for a functional dimeric form of the PcrA helicase in DNA unwinding.

    PubMed

    Yang, Ye; Dou, Shuo-Xing; Ren, Hua; Wang, Peng-Ye; Zhang, Xing-Dong; Qian, Min; Pan, Bing-Yi; Xi, Xu Guang

    2008-04-01

    PcrA helicase, a member of the superfamily 1, is an essential enzyme in many bacteria. The first crystal structures of helicases were obtained with PcrA. Based on structural and biochemical studies, it was proposed and then generally believed that PcrA is a monomeric helicase that unwinds DNA by an inchworm mechanism. But a functional state of PcrA from unwinding kinetics studies has been lacking. In this work, we studied the kinetic mechanism of PcrA-catalysed DNA unwinding with fluorometric stopped-flow method under both single- and multiple-turnover conditions. It was found that the PcrA-catalysed DNA unwinding depended strongly on the PcrA concentration as well as on the 3'-ssDNA tail length of the substrate, indicating that an oligomerization was indispensable for efficient unwinding. Study of the effect of ATP concentration on the unwinding rate gave a Hill coefficient of approximately 2, suggesting strongly that PcrA functions as a dimer. It was further determined that PcrA unwound DNA with a step size of 4 bp and a rate of approximately 9 steps per second. Surprisingly, it was observed that PcrA unwound 12-bp duplex substrates much less efficiently than 16-bp ones, highlighting the importance of protein-DNA duplex interaction in the helicase activity. From the present studies, it is concluded that PcrA is a dimeric helicase with a low processivity in vitro. Implications of the experimental results for the DNA unwinding mechanism of PcrA are discussed.

  17. The structure of apo and holo forms of xylose reductase, a dimeric aldo-keto reductase from Candida tenuis.

    PubMed

    Kavanagh, Kathryn L; Klimacek, Mario; Nidetzky, Bernd; Wilson, David K

    2002-07-16

    Xylose reductase is a homodimeric oxidoreductase dependent on NADPH or NADH and belongs to the largely monomeric aldo-keto reductase superfamily of proteins. It catalyzes the first step in the assimilation of xylose, an aldose found to be a major constituent monosaccharide of renewable plant hemicellulosic material, into yeast metabolic pathways. It does this by reducing open chain xylose to xylitol, which is reoxidized to xylulose by xylitol dehydrogenase and metabolically integrated via the pentose phosphate pathway. No structure has yet been determined for a xylose reductase, a dimeric aldo-keto reductase or a family 2 aldo-keto reductase. The structures of the Candida tenuis xylose reductase apo- and holoenzyme, which crystallize in spacegroup C2 with different unit cells, have been determined to 2.2 A resolution and an R-factor of 17.9 and 20.8%, respectively. Residues responsible for mediating the novel dimeric interface include Asp-178, Arg-181, Lys-202, Phe-206, Trp-313, and Pro-319. Alignments with other superfamily members indicate that these interactions are conserved in other dimeric xylose reductases but not throughout the remainder of the oligomeric aldo-keto reductases, predicting alternate modes of oligomerization for other families. An arrangement of side chains in a catalytic triad shows that Tyr-52 has a conserved function as a general acid. The loop that folds over the NAD(P)H cosubstrate is disordered in the apo form but becomes ordered upon cosubstrate binding. A slow conformational isomerization of this loop probably accounts for the observed rate-limiting step involving release of cosubstrate. Xylose binding (K(m) = 87 mM) is mediated by interactions with a binding pocket that is more polar than a typical aldo-keto reductase. Modeling of xylose into the active site of the holoenzyme using ordered waters as a guide for sugar hydroxyls suggests a convincing mode of substrate binding.

  18. Icariin improves eNOS/NO pathway to prohibit the atherogenesis of apolipoprotein E-null mice.

    PubMed

    Xiao, Hong-Bo; Sui, Guo-Guang; Lu, Xiang-Yang

    2016-12-22

    Impaired endothelial nitric oxide synthase (eNOS)/nitric oxide (NO) pathway induces atherogenesis. The present study examined whether icariin improves the eNOS/NO pathway to prohibit the atherogenesis of apolipoprotein E-null (ApoE(-/-)) mice. In vitro, primary human umbilical vein endothelial cells (HUVECs) were randomly divided into 7 groups: control; vehicle; icariin 10; lyphosphatidylcholine (LPC) group; LPC + icariin 1; LPC + icariin 3; and LPC + icariin 10. In vivo, 80 mice were separated randomly into 4 groups (n = 20): control, ApoE(-/-), ApoE(-/-) + icariin 10, and ApoE(-/-) + icariin 30. ApoE(-/-) mice had significantly more atherosclerosis in the aortic root together with increased aortic ROS production, body mass, plasma triglyceride (TG) and total cholesterol (TC) concentration, decreased aortic eNOS expression, and plasma NO concentration. LPC (10 μg/mL) treatment induced a big decline in NO level in the conditioned medium and eNOS expression, and an increase in intracellular reactive oxygen species (ROS) production in HUVECs. Icariin treatment decreased atherogenesis, ROS production, body mass, plasma TG concentration, and plasma TC concentration, and increased NO concentration and eNOS expression. These findings suggested icariin could improve eNOS/NO-pathway to prohibit the atherogenesis of apolipoprotein E-null mice by restraining oxidative stress.

  19. The carp muscle-specific sub-isoenzymes of creatine kinase form distinct dimers at different temperatures.

    PubMed Central

    Sun, Hsi-Wen; Liu, Cheng-Wen; Hui, Cho-Fat; Wu, Jen-Leih

    2002-01-01

    We have previously cloned three muscle-specific sub-isoforms of creatine kinase (CK, EC 2.7.3.2) from the common carp ( Cyprinus carpio ), designated M1-CK, M2-CK, and M3-CK. The enzyme has a key role in maintaining the energy homoeostasis of cells with fluctuating energy requirements. In the present paper, we report that all three M-CKs in the red and white muscle of different temperature-acclimatized carp were ubiquitously distributed in the cytosol and along membranes. In addition, the expression levels of these isoforms were not significantly altered in response to the temperature acclimatization. Interestingly, our studies showed that the formation of distinct homo- or heterodimers among these three M-CKs was found at various temperatures. At higher temperature, the M1M1-CK and M2M2-CK homodimers, and the M1M3-CK heterodimer are the predominant MM-CKs, whereas the M3M3-CK achieves its homodimeric state at lower temperature. We postulated testable homology models to investigate the chemical properties of these dimeric interfaces. M1M1-CK was used as a reference to compare the structural differences with the M3M3-CK dimer. The calculated solvent accessible surface area that was buried in the contact interfaces of the M1M1-CK and M3M3-CK dimers showed an overall decrease of 12% in the M3M3-CK interface. The modelling analysis also suggested a net decrease of twelve hydrophobic residues and a Phe(3)-->Lys substitution in the M3M3-CK interface. An increase in thermolability of the M3M3-CK homodimer might be due to the decrease in subunit ion pairs and buried surface area in this dimer. Based on our findings, we propose that the carp-muscle-specific CK isoenzymes could undergo shuffling to form distinct M-CK homo- or heterodimers in acclimatization to environmental temperatures. PMID:12213085

  20. Terpenylic and Related Lactone-Containing Acids: Novel Monoterpene Secondary Organic Aerosol Tracers with Dimer-Forming Properties

    NASA Astrophysics Data System (ADS)

    Claeys, M.; Iinuma, Y.; Szmigielski, R.; Farhat, Y.; Surratt, J. D.; Blockhuys, F.; van Alsenoy, C.; Böge, O.; Sierau, B.; Gómez-González, Y.; Vermeylen, R.; van der Veken, P.; Shahgholi, M.; Chan, A. W.; Herrmann, H.; Seinfeld, J.; Maenhaut, W.

    2009-12-01

    Blue haze is a natural phenomenon that is observed in forested regions worldwide and is due to the formation of secondary organic aerosol (SOA) particles. While evidence exists for organic molecular clusters in the size range of < 2 nm, the chemical structures of the nucleating particles have remained unresolved. In the present study, novel SOA products from the monoterpene α-pinene with unique dimer-forming properties have been identified as lactone-containing terpenoic acids, i.e., terpenylic (molecular weight (MW) 172), terebic (MW 158) and 2-hydroxyterpenylic acid (MW 188), and diaterpenylic acid acetate (MW 232). The structural characterizations were based on synthesis of reference compounds and detailed interpretation of negative ion electrospray ionization mass spectral [(-)ESI-MS] data, including accurate mass and MSn ion trap measurements. Terpenylic acid and diaterpenylic acid acetate are early oxidation products formed upon both photooxidation and ozonolysis, and are abundant SOA tracers in ambient fine aerosol from coniferous forest sites (e.g., K-puszta, Hungary). Terebic and 2-hydroxyterpenylic acid can be explained by further oxidation of terpenylic acid, and are also prominent tracers in ambient fine aerosol. Quantum chemical calculations support that non-covalent dimer formation involving double hydrogen bonding interactions between carboxyl groups of the monomers is energetically favorable. Lactone-containing terpenoic acids also form through photooxidation from monoterpenes other than α-pinene, i.e., terebic acid from Δ3-carene, and terpenylic, homoterpenylic (MW 186), and terebic acid from β-pinene. A distinct feature of terpenylic acid and related lactone-containing acids is that they can be selectively detected in positive ion (+)ESI-MS, unlike isobaric dicarboxylic terpenoic acids such as norpinic (MW 172) and pinic acid (MW 186). Interestingly, terpenylic, terebic and homoterpenylic acid were already reported in the early German

  1. The dimeric form of HLA-G molecule is associated with the response of early rheumatoid arthritis (ERA) patients to methotrexate.

    PubMed

    Rizzo, Roberta; Farina, Ilaria; Bortolotti, Daria; Galuppi, Elisa; Padovan, Melissa; Di Luca, Dario; Govoni, Marcello

    2017-03-01

    A growing body of evidence indicates a possible involvement of HLA (human leukocyte antigen)-G antigens in rheumatoid arthritis (RA), mainly in the HLA-G dimeric isoform, the most active HLA-G form with the strongest immunosuppression, that showed an excellent anti-inflammatory effect in collagen-induced arthritis model mice. However, the relevance of HLA-G dimers in RA response to methotrexate (MTX) treatment is still unknown. We analyzed the HLA-G dimers' amount in plasma samples from early rheumatoid arthritis (ERA) patients before MTX therapy and evaluated the role of these molecules as biomarker of the different response to the treatment. Plasma sHLA-G levels were detected by ELISA, and HLA-G dimeric and monomeric forms were revealed by Western blot in 12 MTX responder (reaching DAS28 remission <2.6) and 8 MTX non-responder (DAS28 ≥5.1) patients before the therapy. The response to MTX was evaluated after 6 months of treatment. All ERA patients reaching remission showed higher plasma sHLA-G levels and the 78 kDa HLA-G dimeric form. Unresponsive ERA patients were characterized by lower plasma sHLA-G levels, and only one patient presented the 78 kDa HLA-G dimeric form (DAS28 5.1). Our preliminary results support the hypothesis that in ERA patients, sHLA-G and, in particular, the presence of the dimeric form in plasma samples before MTX therapy could be an a priori biomarker for the response to MTX treatment.

  2. Preliminary crystallographic analysis of a double mutant of the acetyl xylo-oligosaccharide esterase Axe2 in its dimeric form.

    PubMed

    Lansky, Shifra; Alalouf, Onit; Salama, Rachel; Dvir, Hay; Shoham, Yuval; Shoham, Gil

    2014-04-01

    Xylans are polymeric sugars constituting a significant part of the plant cell wall. They are usually substituted with acetyl side groups attached at positions 2 or 3 of the xylose backbone units. Acetylxylan esterases are part of the hemicellulolytic system of many microorganisms which utilize plant biomass for growth. These enzymes hydrolyze the ester linkages of the xylan acetyl groups and thus improve the accessibility of main-chain-hydrolyzing enzymes and their ability to break down the sugar backbone units. The acetylxylan esterases are therefore critically important for those microorganisms and as such could be used for a wide range of biotechnological applications. The structure of an acetylxylan esterase (Axe2) isolated from the thermophilic bacterium Geobacillus stearothermophilus T6 has been determined, and it has been demonstrated that the wild-type enzyme is present as a unique torus-shaped octamer in the crystal and in solution. In order to understand the functional origin of this unique oligomeric structure, a series of rational noncatalytic, site-specific mutations have been made on Axe2. Some of these mutations led to a different dimeric form of the protein, which showed a significant reduction in catalytic activity. One of these double mutants, Axe2-Y184F-W190P, has recently been overexpressed, purified and crystallized. The best crystals obtained belonged to the orthorhombic space group P212121, with unit-cell parameters a = 71.1, b = 106.0, c = 378.6 Å. A full diffraction data set to 2.3 Å resolution has been collected from a flash-cooled crystal of this type at 100 K using synchrotron radiation. This data set is currently being used for the three-dimensional structure analysis of the Axe2-Y184F-W190P mutant in its dimeric form.

  3. Proteomic Profile of Unstable Atheroma Plaque: Increased Neutrophil Defensin 1, Clusterin, and Apolipoprotein E Levels in Carotid Secretome.

    PubMed

    Aragonès, Gemma; Auguet, Teresa; Guiu-Jurado, Esther; Berlanga, Alba; Curriu, Marta; Martinez, Salomé; Alibalic, Ajla; Aguilar, Carmen; Hernández, Esteban; Camara, María-Luisa; Canela, Núria; Herrero, Pol; Ruyra, Xavier; Martín-Paredero, Vicente; Richart, Cristóbal

    2016-03-04

    Because of the clinical significance of carotid atherosclerosis, the search for novel biomarkers has become a priority. The aim of the present study was to compare the protein secretion profile of the carotid atherosclerotic plaque (CAP, n = 12) and nonatherosclerotic mammary artery (MA, n = 10) secretomes. We used a nontargeted proteomic approach that incorporated tandem immunoaffinity depletion, iTRAQ labeling, and nanoflow liquid chromatography coupled to high-resolution mass spectrometry. In total, 162 proteins were quantified, of which 25 showed statistically significant differences in secretome levels between carotid atherosclerotic plaque and nondiseased mammary artery. We found increased levels of neutrophil defensin 1, apolipoprotein E, clusterin, and zinc-alpha-2-glycoprotein in CAP secretomes. Results were validated by ELISA assays. Also, differentially secreted proteins are involved in pathways such as focal adhesion and leukocyte transendothelial migration. In conclusion, this study provides a subset of identified proteins that are differently expressed in secretomes of clinical significance.

  4. Evidence for apolipoprotein E {epsilon}4 association in early-onset Alzheimer`s patients with late-onset relatives

    SciTech Connect

    Perez-Tur, J.; Delacourte, A.; Chartier-Harlin, M.C.

    1995-12-18

    Recently several reports have extended the apolipoprotein E (APOE) {epsilon}4 association found in late-onset Alzheimer`s disease (LOAD) patients to early-onset (EO) AD patients. We have studied this question in a large population of 119 EOAD patients (onset {<=}60 years) in which family history was carefully assessed and in 109 controls. We show that the APOE {epsilon}A allele frequency is increased only in the subset of patients who belong to families where LOAD secondary cases are present. Our sampling scheme permits us to demonstrate that, for an individual, bearing at least one {epsilon}4 allele increases both the risk of AD before age 60 and the probability of belonging to a family with late-onset affected subjects. Our results suggest that a subset of EOAD cases shares a common determinism with LOAD cases. 19 refs., 3 tabs.

  5. Allelic association but only weak evidence for linkage to the apolipoprotein E locus in late-onset Swedish Alzheimer families

    SciTech Connect

    Liu, L.; Forsell, C.; Lilius, L.

    1996-05-31

    An association between the {epsilon}4 allele of the apolipoprotein E gene (APOE) and late-onset Alzheimer`s disease (AD) was recently demonstrated. In order to confirm the association and to gauge the ability of standard genetic linkage methods to identify susceptibility genes, we investigated 15 Swedish late-onset AD families. We found an association of familial AD to the APOE {epsilon}4 allele (P = 0.01) but no indication of linkage to the APOE region using 2-point linkage analysis, and only weak evidence using the affected pedigree-member (APM) method. Our results confirm an APOE {epsilon}4 association with late-onset familial AD and indicate that susceptibility genes can easily be missed when using standard lod score and APM genetic linkage analysis. 19 refs., 1 fig., 4 tabs.

  6. Enhanced synthesis and secretion of apolipoprotein E from sciatic nerves of streptozotocin-induced diabetic rats after injury

    SciTech Connect

    Ishibashi, S.; Yamada, N.; Oka, Y.; Shimano, H.; Mori, N.; Yoon, T.H.; Shimada, M.; Kanazawa, Y.; Akanuma, Y.; Murase, T.

    1988-08-30

    To elucidate the pathogenesis of diabetic neuropathy, synthesis and secretion of apolipoprotein E (apo E) from sciatic nerves after injury was studied in normal and streptozotocin-induced diabetic rats. Seven, 14, 28, 45 and 59 days after making crush injury on sciatic nerves with concomitant administration of streptozotocin (50 mg/kg body weight), the nerves were taken out and incubated with (/sup 35/S)methionine. The (/sup 35/S)labeled apo E was precipitated with specific antiserum. The amounts of apo E secreted into medium by nerves of diabetic rats were 7 times greater than those of non-diabetic rats 7 days after injury. This enhanced secretion of apo E was relatively selective for this protein, since the ratio of the immunoprecipitable apo E to the TCA preciptitable protein in the medium increased in diabetic rats. Intriguing possibility deduced from these results is that the secretion of apo E is involved in the development of diabetic neuropathy.

  7. Proteomic Analysis of Plasma from California Sea Lions (Zalophus californianus) Reveals Apolipoprotein E as a Candidate Biomarker of Chronic Domoic Acid Toxicosis.

    PubMed

    Neely, Benjamin A; Ferrante, Jason A; Chaves, J Mauro; Soper, Jennifer L; Almeida, Jonas S; Arthur, John M; Gulland, Frances M D; Janech, Michael G

    2014-01-01

    Domoic acid toxicosis (DAT) in California sea lions (Zalophus californianus) is caused by exposure to the marine biotoxin domoic acid and has been linked to massive stranding events and mortality. Diagnosis is based on clinical signs in addition to the presence of domoic acid in body fluids. Chronic DAT further is characterized by reoccurring seizures progressing to status epilepticus. Diagnosis of chronic DAT is often slow and problematic, and minimally invasive tests for DAT have been the focus of numerous recent biomarker studies. The goal of this study was to retrospectively profile plasma proteins in a population of sea lions with chronic DAT and those without DAT using two dimensional gel electrophoresis to discover whether individual, multiple, or combinations of protein and clinical data could be utilized to identify sea lions with DAT. Using a training set of 32 sea lion sera, 20 proteins and their isoforms were identified that were significantly different between the two groups (p<0.05). Interestingly, 11 apolipoprotein E (ApoE) charge forms were decreased in DAT samples, indicating that ApoE charge form distributions may be important in the progression of DAT. In order to develop a classifier of chronic DAT, an independent blinded test set of 20 sea lions, seven with chronic DAT, was used to validate models utilizing ApoE charge forms and eosinophil counts. The resulting support vector machine had high sensitivity (85.7% with 92.3% negative predictive value) and high specificity (92.3% with 85.7% positive predictive value). These results suggest that ApoE and eosinophil counts along with machine learning can perform as a robust and accurate tool to diagnose chronic DAT. Although this analysis is specifically focused on blood biomarkers and routine clinical data, the results demonstrate promise for future studies combining additional variables in multidimensional space to create robust classifiers.

  8. Expression of the very low-density lipoprotein receptor (VLDL-r), an apolipoprotein-E receptor, in the central nervous system and in Alzheimer`s disease

    SciTech Connect

    Christie, R.H.; Chung, Haeyong; Rebeck, G.W.; Hyman, B.T.

    1996-04-01

    The very low density lipoprotein receptor (VLDL-r) is a cell-surface molecule specialized for the internalization of multiple diverse ligands, including apolipoprotein E (apoE)-containing lipoprotein particles, via clathrin-coated pits. Its structure is similar to the low-density lipoprotein receptor (LDL-r), although the two have substantially different systemic distributions and regulatory pathways. The present work examines the distribution of VLDL-r in the central nervous system (CNS) and in relation to senile plaques in Alzheimer disease (AD). VLDL-r is present on resting and activated microglia, particularly those associated with senile plaques (SPs). VLDL-r immunoreactivity is also found in cortical neurons. Two exons of VLDL-r mRNA are differentially spliced in the mature receptor mRNA. One set of splice forms gives rise to receptors containing (or lacking) an extracellular O-linked glycosylation domain near the transmembrane portion of the molecule. The other set of splice forms appears to be brain-specific, and is responsible for the presence or absence of one of the cysteine-rich repeat regions in the binding region of the molecule. Ratios of the receptor variants generated from these splice forms do not differ substantially across different cortical areas or in AD. We hypothesize that VLDL-r might contribute to metabolism of apoE and apoE/A{beta} complexes in the brain. Further characterization of apoE receptors in Alzheimer brain may help lay the groundwork for understanding the role of apoE in the CNS and in the pathophysiology of AD. 43 refs., 5 figs.

  9. Proteomic Analysis of Plasma from California Sea Lions (Zalophus californianus) Reveals Apolipoprotein E as a Candidate Biomarker of Chronic Domoic Acid Toxicosis

    PubMed Central

    Neely, Benjamin A.; Ferrante, Jason A.; Chaves, J. Mauro; Soper, Jennifer L.; Almeida, Jonas S.; Arthur, John M.; Gulland, Frances M. D.; Janech, Michael G.

    2015-01-01

    Domoic acid toxicosis (DAT) in California sea lions (Zalophus californianus) is caused by exposure to the marine biotoxin domoic acid and has been linked to massive stranding events and mortality. Diagnosis is based on clinical signs in addition to the presence of domoic acid in body fluids. Chronic DAT further is characterized by reoccurring seizures progressing to status epilepticus. Diagnosis of chronic DAT is often slow and problematic, and minimally invasive tests for DAT have been the focus of numerous recent biomarker studies. The goal of this study was to retrospectively profile plasma proteins in a population of sea lions with chronic DAT and those without DAT using two dimensional gel electrophoresis to discover whether individual, multiple, or combinations of protein and clinical data could be utilized to identify sea lions with DAT. Using a training set of 32 sea lion sera, 20 proteins and their isoforms were identified that were significantly different between the two groups (p<0.05). Interestingly, 11 apolipoprotein E (ApoE) charge forms were decreased in DAT samples, indicating that ApoE charge form distributions may be important in the progression of DAT. In order to develop a classifier of chronic DAT, an independent blinded test set of 20 sea lions, seven with chronic DAT, was used to validate models utilizing ApoE charge forms and eosinophil counts. The resulting support vector machine had high sensitivity (85.7% with 92.3% negative predictive value) and high specificity (92.3% with 85.7% positive predictive value). These results suggest that ApoE and eosinophil counts along with machine learning can perform as a robust and accurate tool to diagnose chronic DAT. Although this analysis is specifically focused on blood biomarkers and routine clinical data, the results demonstrate promise for future studies combining additional variables in multidimensional space to create robust classifiers. PMID:25919366

  10. Apolipoprotein E polymorphisms and postprandial triglyceridemia before and after fenofibrate treatment in the Genetics of Lipid Lowering and Diet Network (GOLDN) Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: While much is known about the effect of Apolipoprotein E (APOE) alleles on fasting lipid concentrations, less is known about the effect of APOE alleles on postprandial triglyceridemia or the triglyceride response to fenofibrate. Methods and Results: We evaluated the effects of the APOE l...

  11. Dietary Soy Protein Isolate Ameliorates Atherosclerotic Lesions in Apolipoprotein E-Deficient Mice Potentially by Inhibiting Monocyte Chemoattractant Protein-1 Expression

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soy-based diets reportedly protect against the development of atherosclerosis; however, the underlying mechanism(s) for this protection remains unknown. In this report, the mechanism(s) contributing to the atheroprotective effects of a soy-based diet was addressed using the apolipoprotein E knockout...

  12. Apolipoprotein e4 Is Associated with More Rapid Decline in Odor Identification than in Odor Threshold or Dementia Rating Scale Scores

    ERIC Educational Resources Information Center

    Calhoun-Haney, R.; Murphy, C.

    2005-01-01

    Individuals with the apolipoprotein E e4 genetic risk factor for Alzheimer's disease (AD) show deficits in olfactory function. The purpose of the present study was to examine longitudinally odor identification (odor ID), odor threshold, picture identification, and global cognitive status in allele positive (e4+) and negative (e4-) persons.…

  13. The multiple forms of bovine seminal ribonuclease: structure and stability of a C-terminal swapped dimer.

    PubMed

    Sica, Filomena; Pica, Andrea; Merlino, Antonello; Russo Krauss, Irene; Ercole, Carmine; Picone, Delia

    2013-11-29

    Bovine seminal ribonuclease (BS-RNase) acquires an interesting anti-tumor activity associated with the swapping on the N-terminal. The first direct experimental evidence on the formation of a C-terminal swapped dimer (C-dimer) obtained from the monomeric derivative of BS-RNase, although under non-native conditions, is here reported. The X-ray model of this dimer reveals a quaternary structure different from that of the C-dimer of RNase A, due to the presence of three mutations in the hinge peptide 111-116. The mutations increase the hinge peptide flexibility and decrease the stability of the C-dimer against dissociation. The biological implications of the structural data are also discussed.

  14. Effect of Dimer Dissociation on Activity and Thermostability of the α-Glucuronidase from Geobacillus stearothermophilus: Dissecting the Different Oligomeric Forms of Family 67 Glycoside Hydrolases

    PubMed Central

    Shallom, Dalia; Golan, Gali; Shoham, Gil; Shoham, Yuval

    2004-01-01

    The oligomeric organization of enzymes plays an important role in many biological processes, such as allosteric regulation, conformational stability and thermal stability. α-Glucuronidases are family 67 glycosidases that cleave the α-1,2-glycosidic bond between 4-O-methyl-d-glucuronic acid and xylose units as part of an array of hemicellulose-hydrolyzing enzymes. Currently, two crystal structures of α-glucuronidases are available, those from Geobacillus stearothermophilus (AguA) and from Cellvibrio japonicus (GlcA67A). Both enzymes are homodimeric, but surprisingly their dimeric organization is different, raising questions regarding the significance of dimerization for the enzymes' activity and stability. Structural comparison of the two enzymes suggests several elements that are responsible for the different dimerization organization. Phylogenetic analysis shows that the α-glucuronidases AguA and GlcA67A can be classified into two distinct subfamilies of bacterial α-glucuronidases, where the dimer-forming residues of each enzyme are conserved only within its own subfamily. It seems that the different dimeric forms of AguA and GlcA67A represent the two alternative dimeric organizations of these subfamilies. To study the biological significance of the dimerization in α-glucuronidases, we have constructed a monomeric form of AguA by mutating three of its interface residues (W328E, R329T, and R665N). The activity of the monomer was significantly lower than the activity of the wild-type dimeric AguA, and the optimal temperature for activity of the monomer was around 35°C, compared to 65°C of the wild-type enzyme. Nevertheless, the melting temperature of the monomeric protein, 72.9°C, was almost identical to that of the wild-type, 73.4°C. It appears that the dimerization of AguA is essential for efficient catalysis and that the dissociation into monomers results in subtle conformational changes in the structure which indirectly influence the active site region

  15. Effect of dimer dissociation on activity and thermostability of the alpha-glucuronidase from Geobacillus stearothermophilus: dissecting the different oligomeric forms of family 67 glycoside hydrolases.

    PubMed

    Shallom, Dalia; Golan, Gali; Shoham, Gil; Shoham, Yuval

    2004-10-01

    The oligomeric organization of enzymes plays an important role in many biological processes, such as allosteric regulation, conformational stability and thermal stability. alpha-Glucuronidases are family 67 glycosidases that cleave the alpha-1,2-glycosidic bond between 4-O-methyl-D-glucuronic acid and xylose units as part of an array of hemicellulose-hydrolyzing enzymes. Currently, two crystal structures of alpha-glucuronidases are available, those from Geobacillus stearothermophilus (AguA) and from Cellvibrio japonicus (GlcA67A). Both enzymes are homodimeric, but surprisingly their dimeric organization is different, raising questions regarding the significance of dimerization for the enzymes' activity and stability. Structural comparison of the two enzymes suggests several elements that are responsible for the different dimerization organization. Phylogenetic analysis shows that the alpha-glucuronidases AguA and GlcA67A can be classified into two distinct subfamilies of bacterial alpha-glucuronidases, where the dimer-forming residues of each enzyme are conserved only within its own subfamily. It seems that the different dimeric forms of AguA and GlcA67A represent the two alternative dimeric organizations of these subfamilies. To study the biological significance of the dimerization in alpha-glucuronidases, we have constructed a monomeric form of AguA by mutating three of its interface residues (W328E, R329T, and R665N). The activity of the monomer was significantly lower than the activity of the wild-type dimeric AguA, and the optimal temperature for activity of the monomer was around 35 degrees C, compared to 65 degrees C of the wild-type enzyme. Nevertheless, the melting temperature of the monomeric protein, 72.9 degrees C, was almost identical to that of the wild-type, 73.4 degrees C. It appears that the dimerization of AguA is essential for efficient catalysis and that the dissociation into monomers results in subtle conformational changes in the structure

  16. The HC fragment of tetanus toxin forms stable, concentration-dependent dimers via an intermolecular disulphide bond.

    PubMed

    Qazi, Omar; Bolgiano, Barbara; Crane, Dennis; Svergun, Dmitri I; Konarev, Petr V; Yao, Zhong-Ping; Robinson, Carol V; Brown, Katherine A; Fairweather, Neil

    2007-01-05

    Protein oligomerisation is a prerequisite for the toxicity of a number of bacterial toxins. Examples include the pore-forming cytotoxin streptolysin O, which oligomerises to form large pores in the membrane and the protective antigen of anthrax toxin, where a heptameric complex is essential for the delivery of lethal factor and edema factor to the cell cytosol. Binding of the clostridial neurotoxins to receptors on neuronal cells is well characterised, but little is known regarding the quaternary structure of these toxins and the role of oligomerisation in the intoxication process. We have investigated the oligomerisation of the receptor binding domain (H(C)) of tetanus toxin, which retains the binding and trafficking properties of the full-length toxin. Electrophoresis, size exclusion chromatography and mass spectrometry were used to demonstrate that H(C) undergoes concentration-dependent oligomerisation in solution. Reducing agents were found to affect H(C) oligomerisation and, using mutagenesis, Cys869 was shown to be essential for this process. Furthermore, the oligomeric state and quaternary structure of H(C) in solution was assessed using synchrotron small-angle X-ray scattering. Ab initio shape analysis and rigid body modelling coupled with mutagenesis data allowed the construction of an unequivocal model of dimeric H(C) in solution. We propose a possible mechanism for H(C) oligomerisation and discuss how this may relate to toxicity.

  17. Dimerization, oligomerization, and aggregation of human amyotrophic lateral sclerosis copper/zinc superoxide dismutase 1 protein mutant forms in live cells.

    PubMed

    Kim, Jiho; Lee, Honggun; Lee, Joo Hyun; Kwon, Do-yoon; Genovesio, Auguste; Fenistein, Denis; Ogier, Arnaud; Brondani, Vincent; Grailhe, Regis

    2014-05-23

    More than 100 copper/zinc superoxide dismutase 1 (SOD1) genetic mutations have been characterized. These mutations lead to the death of motor neurons in ALS. In its native form, the SOD1 protein is expressed as a homodimer in the cytosol. In vitro studies have shown that SOD1 mutations impair the dimerization kinetics of the protein, and in vivo studies have shown that SOD1 forms aggregates in patients with familial forms of ALS. In this study, we analyzed WT SOD1 and 9 mutant (mt) forms of the protein by non-invasive fluorescence techniques. Using microscopic techniques such as fluorescence resonance energy transfer, fluorescence complementation, image-based quantification, and fluorescence correlation spectroscopy, we studied SOD1 dimerization, oligomerization, and aggregation. Our results indicate that SOD1 mutations lead to an impairment in SOD1 dimerization and, subsequently, affect protein aggregation. We also show that SOD1 WT and mt proteins can dimerize. However, aggregates are predominantly composed of SOD1 mt proteins.

  18. LexA repressor forms stable dimers in solution. The role of specific dna in tightening protein-protein interactions.

    PubMed

    Mohana-Borges, R; Pacheco, A B; Sousa, F J; Foguel, D; Almeida, D F; Silva, J L

    2000-02-18

    Cooperativity in the interactions among proteins subunits and DNA is crucial for DNA recognition. LexA repressor was originally thought to bind DNA as a monomer, with cooperativity leading to tighter binding of the second monomer. The main support for this model was a high value of the dissociation constant for the LexA dimer (micromolar range). Here we show that the protein is a dimer at nanomolar concentrations under different conditions. The reversible dissociation of LexA dimer was investigated by the effects of hydrostatic pressure or urea, using fluorescence emission and polarization to monitor the dissociation process. The dissociation constant lies in the picomolar range (lower than 20 pM). LexA monomers associate with an unusual large volume change (340 ml/mol), indicating the burial of a large surface area upon dimerization. Whereas nonspecific DNA has no stabilizing effect, specific DNA induces tightening of the dimer and a 750-fold decrease in the K(d). In contrast to the previous model, a tight dimer rather than a monomer is the functional repressor. Accordingly, the LexA dimer only loses its ability to recognize a specific DNA sequence by RecA-induced autoproteolysis. Our work provides insights into the linkage between protein-protein interactions, DNA recognition, and DNA repair.

  19. Succinyl-5-aminoimidazole-4-carboxamide-1-ribose 5'-Phosphate (SAICAR) Activates Pyruvate Kinase Isoform M2 (PKM2) in Its Dimeric Form.

    PubMed

    Yan, Ming; Chakravarthy, Srinivas; Tokuda, Joshua M; Pollack, Lois; Bowman, Gregory D; Lee, Young-Sam

    2016-08-23

    Human pyruvate kinase isoform M2 (PKM2) is a glycolytic enzyme isoform implicated in cancer. Malignant cancer cells have higher levels of dimeric PKM2, which is regarded as an inactive form of tetrameric pyruvate kinase. This perceived inactivity has fueled controversy about how the dimeric form of pyruvate kinase might contribute to cancer. Here we investigate enzymatic properties of PKM2(G415R), a variant derived from a cancer patient, which we show by size-exclusion chromatography and small-angle X-ray scattering to be a dimer that cannot form a tetramer in solution. Although PKM2(G415R) binds to fructose 1,6-bisphosphate (FBP), unlike the wild type this PKM2 variant shows no activation by FBP. In contrast, PKM2(G415R) is activated by succinyl-5-aminoimidazole-4-carboxamide-1-ribose 5'-phosphate (SAICAR), an endogenous metabolite that we previously showed correlates with an increased level of cell proliferation and promotes protein kinase activity of PKM2. Our results demonstrate an important and unexpected enzymatic activity of the PKM2 dimer that likely has a key role in cancer progression.

  20. Apolipoprotein E inhibits osteoclast differentiation via regulation of c-Fos, NFATc1 and NF-κB

    SciTech Connect

    Kim, Woo-Shin; Kim, Hyung Joon; Lee, Zang Hee; Lee, Youngkyun; Kim, Hong-Hee

    2013-02-15

    Apolipoprotein E (ApoE) plays a major role in the transport and metabolism of lipid. Other functions of ApoE include modulation of innate and adaptive immune responses. The expression of ApoE in osteoblasts and its relevance with bone formation have also been reported. However, the effect of ApoE on osteoclasts has not yet been examined. Here, we investigated the role of ApoE in osteoclast differentiation using bone marrow-derived macrophages (BMMs) and RAW264.7 cells. We found a down-regulation of ApoE gene expression during osteoclastic differentiation of those cells. Overexpression of ApoE in BMMs and RAW264.7 cells significantly blocked the induction of c-Fos and nuclear factor of activated T cell c1 (NFATc1), transcription factors critical for expression of osteoclast marker genes, by receptor activator of nuclear factor κB ligand (RANKL), the osteoclast differentiation factor. ApoE inhibited osteoclast differentiation, as measured by decreased number of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells (MNCs). In addition, ApoE reduced the expression of dendritic cell-specific transmembrane protein (DC-STAMP) and ATPase, H{sup +} transporting, lysosomal 38 kDa, V0 subunit d2 (ATP6v0d2), genes involved in cell–cell fusion during osteoclastogenesis. Knock-down of ApoE using a specific siRNA promoted the RANKL-mediated induction of osteoclast differentiation. While ApoE did not affect the activation of ERK, JNK, and p38 MAPK signaling pathways by RANKL, the phosphorylation of p65 trans-activation domain on serine 536 and transcription activity of NF-κB were reduced by ApoE overexpression. These findings suggest that ApoE plays an inhibitory role in osteoclast differentiation via the suppression of RANKL-dependent activation of NF-κB and induction of c-Fos and NFATc1. - Highlights: ► Apolipoprotein E (ApoE) significantly inhibited osteoclast differentiation and activation of NF-κB. ► ApoE decreased the induction of osteoclast marker

  1. Apolipoprotein E-knockout mice on high-fat diet show autoimmune injury on kidney and aorta

    SciTech Connect

    Wang, Yuehai; Lu, Huixia; Huang, Ziyang; Lin, Huili; Lei, Zhenmin; Tang, Mengxiong; Gao, Fei; Dong, Mei; Li, Rongda; Lin, Ling

    2014-07-18

    Highlights: • Titers of ANA and anti-dsDNA antibodies were similar in ApoE{sup −/−} and Fas{sup −/−} mice. • The spleen weights and glomerular areas were similar in ApoE{sup −/−} and Fas{sup −/−} mice. • Expressions of IgG and C3 in glomeruli were similar in ApoE{sup −/−} and Fas{sup −/−} mice. • IgG, C3 and macrophage infiltration in aortic plaques were found in ApoE{sup −/−} mice. - Abstract: Background: Apolipoprotein E-knockout (ApoE{sup −/−}) mice is a classic model of atherosclerosis. We have found that ApoE{sup −/−} mice showed splenomegaly, higher titers of serum anti-nuclear antibody (ANA) and anti-dsDNA antibody compared with C57B6/L (B6) mice. However, whether ApoE{sup −/−} mice show autoimmune injury remains unclear. Methods and results: Six females and six males in each group, ApoE{sup −/−}, Fas{sup −/−} and B6 mice, were used in this study. The titers of serum ANA, anti-dsDNA antibody and creatinine and urine protein were measured by ELISA after 4 months of high-fat diet. The spleen weight and the glomerular area were determined. The expressions of IgG, C3 and macrophage in kidney and atherosclerotic plaque were detected by immunostaining followed by morphometric analysis. Similar to the characteristics of Fas{sup −/−} mice, a model of systemic lupus erythematosus (SLE), ApoE{sup −/−} mice, especially female, displayed significant increases of spleen weight and glomerular area when compared to B6 mice. Also, elevated titers of serum ANA, anti-dsDNA antibody and creatinine and urine protein. Moreover, the expressions of IgG, C3 and macrophage in glomeruli and aortic plaques were found in ApoE{sup −/−} mice. In addition, the IgG and C3 expressions in glomeruli and plaques significantly increased (or a trend of increase) in female ApoE{sup −/−} mice compared with males. Conclusions: Apolipoprotein E-knockout mice on high-fat diet show autoimmune injury on kidney and aorta.

  2. The Apolipoprotein E Polymorphism rs7412 Associates with Body Fatness Independently of Plasma Lipids in Middle Aged Men

    PubMed Central

    Tejedor, M. Teresa; Garcia-Sobreviela, Maria Pilar; Ledesma, Marta; Arbones-Mainar, Jose M.

    2014-01-01

    Background The apolipoprotein E (APOE) gene is polymorphic, encoding one of 3 common alleles (ε2, ε3, ε4) produced from combinations of 2 non-synonymous SNPs (rs429358 and rs7412). APOE plays an important role controlling plasma lipids but its association with adipocyte functionality and body fatness remains to be determined. Methods We analyzed fasting plasma lipids and genotyped the two main APOE-SNPs (rs429358 and rs7412), both located in the fourth exon of the APOE, in 4660 Caucasian middle-aged men free of cardiovascular disease. Results The rs7412 SNP, which determines the APOE2 isoform, was significantly associated with Body Mass Index (BMI) and Waist Girth (WG) in a multivariate model accounting for age, smoking status and plasma lipids. BMI and WG were highest in TT homozygotes and lowest in CC homozygotes. This effect was independent of the rs429358 SNP, which failed to show any association with the BMI and WG variables. The odds ratio of being obese (BMI>30) for individuals carrying the APOε2 allele, present in 14% of the cohort and defined by the rs7412 SNP, was also significant in this multivariate model, with an OR of 1.27 (95% CI: 1.01–1.59). Conclusions This study provides an evidence of a lipid-independent association between the APOE SNP rs7412 and body fatness surrogates, BMI and WG, in a large cohort of middle-aged males. PMID:25268647

  3. Demographic and Lifestyle Characteristics, but Not Apolipoprotein E Genotype, Are Associated with Intelligence among Young Chinese College Students

    PubMed Central

    Wang, Tingting; Zhang, Zhen-Lian; Wang, Yiwei; Heckman, Michael G.; Diehl, Nancy N.; Zhang, Yun-Wu; Xu, Huaxi; Bu, Guojun

    2015-01-01

    Background Intelligence is an important human feature that strongly affects many life outcomes, including health, life-span, income, educational and occupational attainments. People at all ages differ in their intelligence but the origins of these differences are much debated. A variety of environmental and genetic factors have been reported to be associated with individual intelligence, yet their nature and contribution to intelligence differences have been controversial. Objective To investigate the contribution of apolipoprotein E (APOE) genotype, which is associated with the risk for Alzheimer’s disease, as well as demographic and lifestyle characteristics, to the variation in intelligence. Methods A total of 607 Chinese college students aged 18 to 25 years old were included in this prospective observational study. The Chinese revision of Wechsler Adult Intelligence Scale (the fourth edition, short version) was used to determine the intelligence level of participants. Demographic and lifestyle characteristics data were obtained from self-administered questionnaires. Results No significant association was found between APOE polymorphic alleles and different intelligence quotient (IQ) measures. Interestingly, a portion of demographic and lifestyle characteristics, including age, smoking and sleep quality were significantly associated with different IQ measures. Conclusions Our findings indicate that demographic features and lifestyle characteristics, but not APOE genotype, are associated with intelligence measures among young Chinese college students. Thus, although APOE ε4 allele is a strong genetic risk factor for Alzheimer’s disease, it does not seem to impact intelligence at young ages. PMID:26574747

  4. Tongxinluo mitigates atherogenesis by regulating angiogenic factors and inhibiting vasa vasorum neovascularization in apolipoprotein E-deficient mice

    PubMed Central

    Ma, Lianyue; Ni, Mei; Hao, Panpan; Lu, Huixia; Yang, Xiaoyan; Xu, Xingli; Zhang, Cheng; Huang, Shanying; Zhao, Yuxia; Liu, Xiaoling; Zhang, Yun

    2016-01-01

    Vasa vasorum (VV) neovascularization contributes to atherogenesis and its expansion and distribution is correlated with intraplaque expression of angiogenic factors. The present study investigated the roles of Tongxinluo (TXL), a traditional Chinese medication, on VV proliferation and atherogenesis. In vitro, TXL pre-treatment reversed the tumor necrosis factor-a (TNF-a) induced expression of vascular endothelial growth factor A (VEGF-A) and angiopoietin-1 (ANGPT-1) but not ANGPT-2, leading to increased ratio of ANGPT-1 to ANGPT-2. Consistently, TXL treatment (at a dosage of 0.38, 0.75, 1.5 g/kg/d, respectively) decreased the expression of VEGF-A while increased that of ANGPT-1 in early atherosclerotic lesions of apolipoprotein E deficient (apoE−/−) mice. On aortic ring assay, microvessels sprouting from aortas were significantly inhibited in TXL-treated mice. Moreover, VV neovascularization in plaques was markedly reduced with TXL treatment. Histological and morphological analysis demonstrated that TXL treatment reduced plaque burden, plaque size and changed the plaque composition. These data suggest that TXL inhibits early atherogenesis through regulating angiogenic factor expression and inhibiting VV proliferation in atherosclerotic plaque. Our study shed new light on the anti-atherosclerotic effect of TXL. PMID:26908443

  5. Apolipoprotein E (ApoE) polymorphism is related to differences in potential fertility in women: a case of antagonistic pleiotropy?

    PubMed

    Jasienska, Grazyna; Ellison, Peter T; Galbarczyk, Andrzej; Jasienski, Michal; Kalemba-Drozdz, Malgorzata; Kapiszewska, Maria; Nenko, Ilona; Thune, Inger; Ziomkiewicz, Anna

    2015-03-22

    The alleles that are detrimental to health, especially in older age, are thought to persist in populations because they also confer some benefits for individuals (through antagonistic pleiotropy). The ApoE4 allele at the ApoE locus, encoding apolipoprotein E (ApoE), significantly increases risk of poor health, and yet it is present in many populations at relatively high frequencies. Why has it not been replaced by natural selection with the health-beneficial ApoE3 allele? ApoE is a major supplier of cholesterol precursor for the production of ovarian oestrogen and progesterone, thus ApoE has been suggested as the potential candidate gene that may cause variation in reproductive performance. Our results support this hypothesis showing that in 117 regularly menstruating women those with genotypes with at least one ApoE4 allele had significantly higher levels of mean luteal progesterone (144.21 pmol l(-1)) than women with genotypes without ApoE4 (120.49 pmol l(-1)), which indicates higher potential fertility. The hormonal profiles were based on daily data for entire menstrual cycles. We suggest that the finding of higher progesterone in women with ApoE4 allele could provide first strong evidence for an evolutionary mechanism of maintaining the ancestral and health-worsening ApoE4 allele in human populations.

  6. Characterization of five new mutants in the carboxyl-terminal domain of human apolipoprotein E: No cosegregation with severe hyperlipidemia

    SciTech Connect

    Maagdenberg, A.M.J.M. van den; Bruijn, I.H. de; Hofker, M.H.; Frants, R.R. ); Knijff, P. de; Smelt, A.H.M.; Leuven, J.A.G.; van't Hooft, F.; Assmann, G.; Havekes, L.M. ); Weng, Wei; Funke, H. )

    1993-05-01

    Assessment of the apolipoprotein E (apoE) phenotype by isoelectric focusing of both hyperlipidemic and normolipidemic individuals identified five new variants. All mutations were confined to the downstream part of the APOE gene by using denaturing gradient gel electrophoresis (DGGE). Sequence analysis revealed five new mutations causing unique amino acid substitutions in the carboxyl-terminal part of the protein containing the putative lipid-binding domain. Three hyperlipoproteinemic probands were carriers of the APOE*2(Va1236[r arrow]Glu) allele, the APOE*3(Cys112-Arg; Arg251[r arrow]Gly) allele, or the APOE*1(Arg158[r arrow]Cys; Leu252[r arrow]Glu) allele. DGGE of the region encoding the receptor-binding domain was useful for haplotyping the mutations at codons 112 and 158. Family studies failed to demonstrate cosegregation between the new mutations and severe hyperlipoproteinemia, although a number of carriers for the APOE*3(Cys112[r arrow]Arg; Arg251[r arrow]Gly) allele and the APOE*1(Arg158-Cys; Leu252[r arrow]Glu) allele expressed hypertriglyceridemia and/ or hypercholesterolemia. Two other mutant alleles, APOE*4[sup [minus

  7. Apolipoprotein E epsilon 4 allele distribution in Wernicke-Korsakoff syndrome with or without global intellectual deficits.

    PubMed

    Muramatsu, T; Kato, M; Matsui, T; Yoshimasu, H; Yoshino, A; Matsushita, S; Higuchi, S; Kashima, H

    1997-01-01

    Recent genetic studies show that the apolipoprotein E (ApoE) epsilon 4 allele is a risk factor for Alzheimer's disease (AD). Whether this allele is associated with other dementing diseases is the next important question. The information could provide a clue to the pathogenetic role of ApoE. In the present study, patients with Wernicke-Korsakoff syndrome (WKS) of alcoholic etiology were divided into two groups according to the severity of intellectual deficits, i.e., those of "classical" Korsakoff patients with preserved intellectual function other than amnesia and those with global intellectual deficits. Genotyping showed that the frequency of ApoE epsilon 4 allele was significantly higher in the patients with global deficits, suggesting the involvement of this allele in the intellectual decline of WKS. In contrast, distributions of other two markers, alpha 1-antichymotrypsin and presenilin-1, did not differ between the two groups. These results added further support to the notion that the consequence of acute insult to the brain is influenced by the ApoE genotype, and suggested ApoE's role in the development of a certain group of "alcoholic dementia."

  8. Dynamic imaging of allogeneic adipose-derived regenerative cells transplanted in ischemic hind limb of apolipoprotein E mouse model

    PubMed Central

    Zheng, Yi; Qin, Jinbao; Wang, Xin; Peng, Zhiyou; Hou, Peiyong; Lu, Xinwu

    2017-01-01

    Background Transplantation of allogeneic adipose-derived regenerative cells (ADRCs) is a promising treatment modality for severe ischemic diseases. However, minimal information is available on the in vivo effects, fate, and migration of ADRCs, as well as the mechanisms of their therapeutic angiogenesis. Materials and methods In this study, green fluorescent protein-expressing ADRCs (GFP-ADRCs) were obtained, labeled with acetylated 3-aminopropyltrimethoxysilane (APTS)-coated iron oxide nanoparticles (APTS NPs), and injected into an old apolipoprotein E knockout (ApoE-KO) mouse model with hind limb ischemia. Then, 3.0 T magnetic resonance imaging (MRI) was performed to dynamically trace the role of ADRCs targeting hind limb ischemia in the ApoE-KO mice model. Results Labeled cells were visualized as large hypointense spots in ischemic muscles by serial 3.0 T MRI scans during a 4-week follow-up. The presence of labeled GFP-ADRCs was confirmed by Prussian blue staining and fluorescence microscopy on postmortem specimens. Conclusion This study showed that allogeneic ADRCs offer great potential application for therapeutic angiogenesis in severe ischemic disease based on the efficacy and feasibility of ADRC transplantation and on the available amounts of tissue. PMID:28053524

  9. Xanthohumol Prevents Atherosclerosis by Reducing Arterial Cholesterol Content via CETP and Apolipoprotein E in CETP-Transgenic Mice

    PubMed Central

    Segawa, Shuichi; Ozaki, Moeko; Kobayashi, Naoyuki; Shigyo, Tatsuro; Chiba, Hitoshi

    2012-01-01

    Background Xanthohumol is expected to be a potent anti-atherosclerotic agent due to its inhibition of cholesteryl ester transfer protein (CETP). In this study, we hypothesized that xanthohumol prevents atherosclerosis in vivo and used CETP-transgenic mice (CETP-Tg mice) to evaluate xanthohumol as a functional agent. Methodology/Principal Findings Two strains of mice, CETP-Tg and C57BL/6N (wild-type), were fed a high cholesterol diet with or without 0.05% (w/w) xanthohumol ad libitum for 18 weeks. In CETP-Tg mice, xanthohumol significantly decreased accumulated cholesterol in the aortic arch and increased HDL cholesterol (HDL-C) when compared to the control group (without xanthohumol). Xanthohumol had no significant effect in wild-type mice. CETP activity was significantly decreased after xanthohumol addition in CETP-Tg mice compared with the control group and it inversely correlated with HDL-C (%) (P<0.05). Furthermore, apolipoprotein E (apoE) was enriched in serum and the HDL-fraction in CETP-Tg mice after xanthohumol addition, suggesting that xanthohumol ameliorates reverse cholesterol transport via apoE-rich HDL resulting from CETP inhibition. Conclusions Our results suggest xanthohumol prevents cholesterol accumulation in atherogenic regions by HDL-C metabolism via CETP inhibition leading to apoE enhancement. PMID:23166663

  10. Sex Differences in Neuropsychiatric Symptoms of Alzheimer's Disease: The Modifying Effect of Apolipoprotein E ε4 Status.

    PubMed

    Xing, Yi; Tang, Yi; Jia, Jianping

    2015-01-01

    Sex differences in neuropsychiatric symptoms of Alzheimer's disease (AD) have been demonstrated in previous studies, and apolipoprotein E (ApoE) ε4 status influences psychiatric manifestations of AD. However, whether ApoE ε4 status modifies the sex differences in neuropsychiatric symptoms of AD is still unclear. In this study, sex differences in neuropsychiatric abnormalities were stratified and analyzed by ApoE ε4 status in mild AD and moderate to severe AD separately. The Clinical Dementia Rating (CDR) scale and the Neuropsychiatric Inventory (NPI) were used to assess dementia severity and neuropsychiatric symptoms. No sex differences were found in mild AD. In moderate to severe AD, among ε4 positive individuals, disinhibition was significantly more prevalent (8.0% in men versus 43.2% in women, p = 0.003) and severer (p = 0.003) in female patients. The frequency (16.0% in men versus 51.4% in women, p = 0.005) and score (p = 0.004) of irritability were of borderline significance after strict Bonferroni correction. In conclusion, this study supported the modifying effect of ApoE ε4 status on sex differences in neuropsychiatric symptoms of AD, and this modifying effect was pronounced in moderate to severe stage of AD. The interaction between gender and ApoE ε4 status should be considered in studies on neuropsychiatric symptoms of AD.

  11. Angiopoietin-2 attenuates angiotensin II-induced aortic aneurysm and atherosclerosis in apolipoprotein E-deficient mice

    PubMed Central

    Yu, Hongyou; Moran, Corey S.; Trollope, Alexandra F.; Woodward, Lynn; Kinobe, Robert; Rush, Catherine M.; Golledge, Jonathan

    2016-01-01

    Angiogenesis and inflammation are implicated in aortic aneurysm and atherosclerosis and regulated by angiopoietin-2 (Angpt2). The effect of Angpt2 administration on experimental aortic aneurysm and atherosclerosis was examined. Six-month-old male apolipoprotein E deficient (ApoE−/−) mice were infused with angiotensin II (AngII) and administered subcutaneous human Fc-protein (control) or recombinant Angpt2 (rAngpt2) over 14 days. Administration of rAngpt2 significantly inhibited AngII-induced aortic dilatation and rupture of the suprarenal aorta (SRA), and development of atherosclerosis within the aortic arch. These effects were blood pressure and plasma lipoprotein independent and associated with Tie2 activation and down-regulation of monocyte chemotactic protein-1 (MCP-1) within the SRA. Plasma concentrations of MCP-1 and interleukin-6 were significantly lower in mice receiving rAngpt2. Immunostaining for the monocyte/macrophage marker MOMA-2 and the angiogenesis marker CD31 within the SRA were less in mice receiving rAngpt2 than controls. The percentage of inflammatory (Ly6Chi) monocytes within the bone marrow was increased while that in peripheral blood was decreased by rAngpt2 administration. In conclusion, administration of rAngpt2 attenuated angiotensin II-induced aortic aneurysm and atherosclerosis in ApoE−/− mice associated with reduced aortic inflammation and angiogenesis. Up-regulation of Angpt2 may have potential therapeutic value in patients with aortic aneurysm and atherosclerosis. PMID:27767064

  12. Accelerated pericyte degeneration and blood–brain barrier breakdown in apolipoprotein E4 carriers with Alzheimer’s disease

    PubMed Central

    Halliday, Matthew R; Rege, Sanket V; Ma, Qingyi; Zhao, Zhen; Miller, Carol A; Winkler, Ethan A

    2016-01-01

    The blood–brain barrier (BBB) limits the entry of neurotoxic blood-derived products and cells into the brain that is required for normal neuronal functioning and information processing. Pericytes maintain the integrity of the BBB and degenerate in Alzheimer’s disease (AD). The BBB is damaged in AD, particularly in individuals carrying apolipoprotein E4 (APOE4) gene, which is a major genetic risk factor for late-onset AD. The mechanisms underlying the BBB breakdown in AD remain, however, elusive. Here, we show accelerated pericyte degeneration in AD APOE4 carriers >AD APOE3 carriers >non-AD controls, which correlates with the magnitude of BBB breakdown to immunoglobulin G and fibrin. We also show accumulation of the proinflammatory cytokine cyclophilin A (CypA) and matrix metalloproteinase-9 (MMP-9) in pericytes and endothelial cells in AD (APOE4 >APOE3), previously shown to lead to BBB breakdown in transgenic APOE4 mice. The levels of the apoE lipoprotein receptor, low-density lipoprotein receptor-related protein-1 (LRP1), were similarly reduced in AD APOE4 and APOE3 carriers. Our data suggest that APOE4 leads to accelerated pericyte loss and enhanced activation of LRP1-dependent CypA–MMP-9 BBB-degrading pathway in pericytes and endothelial cells, which can mediate a greater BBB damage in AD APOE4 compared with AD APOE3 carriers. PMID:25757756

  13. Human apolipoprotein E ɛ4 expression impairs cerebral vascularization and blood–brain barrier function in mice

    PubMed Central

    Alata, Wael; Ye, Yue; St-Amour, Isabelle; Vandal, Milène; Calon, Frédéric

    2015-01-01

    Human apolipoprotein E (APOE) exists in three isoforms ɛ2, ɛ3, and ɛ4, of which APOE4 is the main genetic risk factor of Alzheimer's disease (AD). As cerebrovascular defects are associated with AD, we tested whether APOE genotype has an impact on the integrity and function of the blood–brain barrier (BBB) in human APOE-targeted replacement mice. Using the quantitative in situ brain perfusion technique, we first found lower (13.0% and 17.0%) brain transport coefficient (Clup) of [3H]-diazepam in APOE4 mice at 4 and 12 months, compared with APOE2 and APOE3 mice, reflecting a decrease in cerebral vascularization. Accordingly, results from immunohistofluorescence experiments revealed a structurally reduced cerebral vascularization (26% and 38%) and thinner basement membranes (30% and 35%) in 12-month-old APOE4 mice compared with APOE2 and APOE3 mice, suggesting vascular atrophy. In addition, APOE4 mice displayed a 29% reduction in [3H]-d-glucose transport through the BBB compared with APOE2 mice without significant changes in the expression of its transporter GLUT1 in brain capillaries. However, an increase of 41.3% of receptor for advanced glycation end products (RAGE) was found in brain capillaries of 12-month-old APOE4 mice. In conclusion, profound divergences were observed between APOE genotypes at the cerebrovascular interface, suggesting that APOE4-induced BBB anomalies may contribute to AD development. PMID:25335802

  14. Site-specific dephosphorylation of tau of apolipoprotein E-deficient and control mice by M1 muscarinic agonist treatment.

    PubMed

    Genis, I; Fisher, A; Michaelson, D M

    1999-01-01

    Apolipoprotein E (apoE)-deficient mice have memory deficits that are associated with synaptic loss of basal forebrain cholinergic projections and with hyperphosphorylation of distinct epitopes of the microtubule-associated protein tau. Furthermore, treatment of apoE-deficient mice with the M1 selective agonist 1-methylpiperidine-4-spiro-(2'-methylthiazoline) [AF150(S)] abolishes their memory deficits and results in recovery of their brain cholinergic markers. In the present study, we used a panel of anti-tau monoclonal antibodies to further map the tau epitopes that are hyperphosphorylated in apoE-deficient mice and examined the effects of prolonged treatment with AF150(S). This revealed that tau of apoE-deficient mice contains a distinct, hyperphosphorylated "hot spot" domain which is localized N-terminally to the microtubule binding domain of tau, and that AF150(S) has an epitope-specific tau dephosphorylating effect whose magnitude is affected by apoE deficiency. Accordingly, epitopes which reside in the hyperphosphorylated "hot spot" are dephosphorylated by AF150(S) in apoE-deficient mice but are almost unaffected in the controls, whereas epitopes which flank this tau domain are dephosphorylated by AF150(S) in both mice groups. In contrast, epitopes located at the N and C terminals of tau are unaffected by AF150(S) in both groups of mice. These findings suggest that apoE deficiency results in hyperphosphorylation of a distinct tau domain whose excess phosphorylation can be reduced by muscarinic treatment.

  15. Comprehensive Plasma Metabolomic Analyses of Atherosclerotic Progression Reveal Alterations in Glycerophospholipid and Sphingolipid Metabolism in Apolipoprotein E-deficient Mice

    PubMed Central

    Dang, Vi T.; Huang, Aric; Zhong, Lexy H.; Shi, Yuanyuan; Werstuck, Geoff H.

    2016-01-01

    Atherosclerosis is the major underlying cause of most cardiovascular diseases. Despite recent advances, the molecular mechanisms underlying the pathophysiology of atherogenesis are not clear. In this study, comprehensive plasma metabolomics were used to investigate early-stage atherosclerotic development and progression in chow-fed apolipoprotein E-deficient mice at 5, 10 and 15 weeks of age. Comprehensive plasma metabolomic profiles, based on 4365 detected metabolite features, differentiate atherosclerosis-prone from atherosclerosis-resistant models. Metabolites in the sphingomyelin pathway were significantly altered prior to detectable lesion formation and at all subsequent time-points. The cytidine diphosphate-diacylglycerol pathway was up-regulated during stage I of atherosclerosis, while metabolites in the phosphatidylethanolamine and glycosphingolipid pathways were augmented in mice with stage II lesions. These pathways, involving glycerophospholipid and sphingolipid metabolism, were also significantly affected during the course of atherosclerotic progression. Our findings suggest that distinct plasma metabolomic profiles can differentiate the different stages of atherosclerotic progression. This study reveals that alteration of specific, previously unreported pathways of glycerophospholipid and sphingolipid metabolism are associated with atherosclerosis. The clear difference in the level of several metabolites supports the use of plasma lipid profiling as a diagnostic tool of atherogenesis. PMID:27721472

  16. Lactobacillus acidophilus ATCC 4356 prevents atherosclerosis via inhibition of intestinal cholesterol absorption in apolipoprotein E-knockout mice.

    PubMed

    Huang, Ying; Wang, Jinfeng; Quan, Guihua; Wang, Xiaojun; Yang, Longfei; Zhong, Lili

    2014-12-01

    The objective of this study was to investigate the effect of Lactobacillus acidophilus ATCC 4356 on the development of atherosclerosis in apolipoprotein E-knockout (ApoE(-/-)) mice. Eight-week-old ApoE(-/-) mice were fed a Western diet with or without L. acidophilus ATCC 4356 daily for 16 weeks. L. acidophilus ATCC 4356 protected ApoE(-/-) mice from atherosclerosis by reducing their plasma cholesterol levels from 923 ± 44 to 581 ± 18 mg/dl, likely via a marked decrease in cholesterol absorption caused by modulation of Niemann-Pick C1-like 1 (NPC1L1). In addition, suppression of cholesterol absorption induced reverse cholesterol transport (RCT) in macrophages through the peroxisome proliferator-activated receptor/liver X receptor (PPAR/LXR) pathway. Fecal lactobacillus and bifidobacterium counts were significantly (P < 0.05) higher in the L. acidophilus ATCC 4356 treatment groups than in the control groups. Furthermore, L. acidophilus ATCC 4356 was detected in the rat small intestine, colon, and feces during the feeding trial. The bacterial levels remained high even after the administration of lactic acid bacteria had been stopped for 2 weeks. These results suggest that administration of L. acidophilus ATCC 4356 can protect against atherosclerosis through the inhibition of intestinal cholesterol absorption. Therefore, L. acidophilus ATCC 4356 may be a potential therapeutic material for preventing the progression of atherosclerosis.

  17. Influence of apolipoprotein E genotype on the transmission of Alzheimer disease in a community-based sample

    SciTech Connect

    Jarvik, G.P.; Larson, E.B.; Goddard, K.

    1996-01-01

    The {epsilon}4 allele of the apolipoprotein E locus (APOE) has been found to be an important predictor of Alzheimer disease (AD). However, linkage analysis has not clarified the role of APOE in the transmission of AD. The results of the current study provide evidence that the pattern of transmission of memory disorders differs in nuclear families in which the AD-affected proband did carry an {epsilon}4 allele versus those families in which the AD-affected proband did not carry an {epsilon}4 allele. Further, risk of AD due to APOE genotype in the probands is modified by family history of memory disorders, suggesting gene-by-gene interactions. Family history remained a significant predictor of AD for affected probands with some, but not all, APOE genotypes in a logistic regression analysis. Though nonadditive in the prediction of AD, APOE genotype and family history acted additively in the prediction of age at AD onset. The results of complex segregation analysis were inconsistent with Mendelian segregation of memory disorders both in families of affected probands who did or did not carry an {epsilon}4 allele, yet these two groups had significantly different parameter estimates for their transmission models. These results are consistent with gene-by-gene interactions, but also could result from common elements in the familial environment. 41 refs., 1 fig., 7 tabs.

  18. A Phytophthora sojae effector PsCRN63 forms homo-/hetero-dimers to suppress plant immunity via an inverted association manner

    PubMed Central

    Li, Qi; Zhang, Meixiang; Shen, Danyu; Liu, Tingli; Chen, Yanyu; Zhou, Jian-Min; Dou, Daolong

    2016-01-01

    Oomycete pathogens produce a large number of effectors to promote infection. Their mode of action are largely unknown. Here we show that a Phytophthora sojae effector, PsCRN63, suppresses flg22-induced expression of FRK1 gene, a molecular marker in pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI). However, PsCRN63 does not suppress upstream signaling events including flg22-induced MAPK activation and BIK1 phosphorylation, indicating that it acts downstream of MAPK cascades. The PsCRN63-transgenic Arabidopsis plants showed increased susceptibility to bacterial pathogen Pseudomonas syringae pathovar tomato (Pst) DC3000 and oomycete pathogen Phytophthora capsici. The callose deposition were suppressed in PsCRN63-transgenic plants compared with the wild-type control plants. Genes involved in PTI were also down-regulated in PsCRN63-transgenic plants. Interestingly, we found that PsCRN63 forms an dimer that is mediated by inter-molecular interactions between N-terminal and C-terminal domains in an inverted association manner. Furthermore, the N-terminal and C-terminal domains required for the dimerization are widely conserved among CRN effectors, suggesting that homo-/hetero-dimerization of Phytophthora CRN effectors is required to exert biological functions. Indeed, the dimerization was required for PTI suppression and cell death-induction activities of PsCRN63. PMID:27243217

  19. Expression of mRNA of apolipoprotein E, apolipoprotein A-IV, and matricellular proteins in the myocardium and intensity of fibroplastic processes during experimental hypercholesterolemia.

    PubMed

    Lushnikova, E L; Nepomnyashchikh, L M; Pichigin, V I; Klinnikova, M G; Nepomnyashchikh, R D; Sergeevichev, D S

    2013-12-01

    The expression of mRNA of matricellular proteins (osteopontin, and lumican), apolipoproteins E and A-IV, and microsomal triglyceride transfer protein, and the intensity of fibroplastic processes were studied in the myocardium of rats during experimental chronic hypercholesterolemia. We have found that the development of chronic hypercholesterolemia was followed by an increase in volume density of interstitial connective tissue in the myocardium reflecting the activation of fibroplastic processes. A slight positive correlation was observed between the connective tissue density in the myocardium and expression of osteopontin mRNA (r=0.408) and lumican mRNA (r=0.470). Myocardium remodeling during hypercholesterolemia is realized against the background of increased expression of apolipoproteins E and A-IV mRNA and microsomal triglyceride transfer protein mRNA involved in transport and metabolism of lipoproteins in several tissues and probably play a pivotal role in the regulation of lipoprotein transport and metabolism in the myocardium. We concluded that the increase in the expression of apolipoproteins (E and A-IV) and microsomal triglyceride transfer protein play adaptive and compensatory role and is related to the increase in lipoprotein utilization by macrophages.

  20. ClC-1 and ClC-2 form hetero-dimeric channels with novel protopore functions.

    PubMed

    Stölting, Gabriel; Fischer, Martin; Fahlke, Christoph

    2014-12-01

    CLC-type chloride channels exhibit a unique double-barreled architecture with two independently functioning ion conduction pathways, the so-called protopores. There exist gating processes that open and close individual protopores as well as common processes that jointly mediate slow opening and closing of both protopores. Different isoforms exhibit distinct voltage dependences and kinetics of gating. Whereas opening of the individual and common gate of homo-dimeric ClC-1 is promoted by membrane depolarization, ClC-2 is closed at positive potentials and opens only at negative voltages. To characterize the functional interaction of protopores we engineered a concatameric construct linking the coding regions of ClC-1 and ClC-2 in an open reading frame, expressed it in mammalian cells and measured anion currents through whole-cell and single channel patch clamping. In the hetero-dimeric assembly, each protopore displayed two kinetically distinct gating processes. Fast gating of the ClC-1 protopore closely resembled fast protopore gating of homo-dimeric channels. The voltage dependence of ClC-2 fast gating was shifted to more positive potentials by the adjacent ClC-1 protopore, resulting in open ClC-2 protopores at positive voltages. We observed two slow gating processes individually acting on ClC-1 and ClC-2 protopores, with distinct time and voltage dependences. Single channel recordings demonstrated that hetero-dimerization additionally modified the unitary conductance of ClC-2 protopores. Our findings suggest that inter-subunit interactions do not only affect common gating, but also ion permeation and gating of individual protopores in hetero-dimeric ClC channels.

  1. Intervertebral Disc Degeneration and Ectopic Bone Formation in Apolipoprotein E Knockout Mice

    PubMed Central

    Zhang, Dawei; Jin, Li; Reames, Davis L.; Shen, Francis H.; Shimer, Adam L.; Li, Xudong

    2012-01-01

    Cardiovascular risk factors are known to be associated with intervertebral disc degeneration, but the underlying mechanism is still unclear. ApoE knockout (KO) mouse is a well-established model for arthrosclerosis. We hypothesize that ApoE may involve in maintaining disc health and ApoE KO mouse develops early disc degeneration. Discs of ApoE KO and wild-type (WT) mice were characterized with histological/immunological, biochemical, and real time RT-PCR assays. A comparison of the extracellular matrix production was also performed in disc cells. We demonstrated that ApoE was highly expressed in the endplates of WT discs and ectopic bone formed in the endplates of ApoE KO discs. Glycosaminoglycan content was decreased in both ApoE KO annulus fibrosus (AF) and nucleus pulpsous (NP) cells. Collagen levels were increased in AF and decreased in NP cells. Matrix metalloproteinases-3, 9, and 13 expression was increased which may partially explain the impaired matrix production. We also found increased collagen I, II, aggrecan and biglycan mRNA expressions in AF cells but decreased in NP cells. Apoptosis was increased in the ApoE KO NP tissue. These results suggest early disc degeneration changes in ApoE KO mice. ApoE, plus its importance to cardiovascular disease, may play a critical role in disc integrity and function. PMID:22915292

  2. Nuclear microprobe investigation into the trace elemental contents of carotid artery walls of apolipoprotein E deficient mice

    NASA Astrophysics Data System (ADS)

    Minqin, Ren; En, Huang; Beck, Konstanze; Rajendran, Reshmi; Wu, Ben J.; Halliwell, Barry; Watt, Frank; Stocker, Roland

    2007-07-01

    Atherosclerosis is a progressive disease that causes lesions in large and medium-sized arteries. There is increasing evidence that the function of vascular endothelial cells is impaired by oxidation reactions, and that metal ions may participate in these processes. The nuclear microscopy facility in NUS, which has the ability to focus a 2 MeV proton beam down to sub micron spot sizes, was used to investigate the trace elemental changes (e.g. Zn and Fe) in atherosclerotic lesions in the common carotid artery of apolipoprotein E deficient mice fed a high fat diet. In this preliminary study, which is part of a larger study to investigate the effects of probucol on carotid artery atherosclerosis, two sets of mice were used; a test set fed a high fat diet +1% probucol, and a control set which was fed a high fat diet only. The results show that the Zn/Fe ratio was significantly higher in the media of arteries of probucol treated animals without overlying lesion (4.3) compared to the media with overlying lesion (1.3) ( p = 0.004) for test mice. For the control mice, the arterial Zn/Fe ratio was 1.8 for media without overlying lesion, compared with 1.0 for media with overlying lesion ( p = 0.1). Thus, for media without overlying lesion, the Zn/Fe ratio was significantly higher ( p = 0.009) in probucol-treated (4.3) than control mice (1.8), whereas there was little difference in the ratios between the two groups in media with overlying lesion (1.3 compared with 1.0). These preliminary results are consistent with the idea that the levels of iron and zinc concentrations within the artery wall may influence the formation of atherosclerotic plaque in the carotid artery.

  3. Source analysis of spontaneous magnetoencephalograpic activity in healthy aging and mild cognitive impairment: influence of apolipoprotein E polymorphism.

    PubMed

    Cuesta, Pablo; Barabash, Ana; Aurtenetxe, Sara; Garcés, Pilar; López, María Eugenia; Bajo, Ricardo; Llanero-Luque, Marcos; Ancín, Inés; Cabranes, José Antonio; Marcos, Alberto; Sancho, Miguel; Nakamura, Akinori; Maestú, Fernando; Fernandez, Alberto

    2015-01-01

    The apolipoprotein E (APOE) ε4 allele is a genetic risk factor for the development of late-onset Alzheimer's disease (AD), which affects cholinergic system functioning. The association between reduced cholinergic levels and increase of magnetoencephalographic (MEG) low-frequency has been used to explain spectral changes found in AD patients. However, the investigation in predementia stages is scarce. We obtained MEG recordings from 25 aged controls and 36 mild cognitive impairment (MCI) patients during a resting-state condition. According to their APOE genotype, MCIs and controls were subdivided in carriers and non-carriers of the ε4 allele. Sources of spectral variations in these groups were calculated through beamforming. MCI patients exhibited a significant increase of relative power within the low-frequency domain, accompanied by a power decrease within the high-frequency range. APOEε4 carriers showed an increased relative power in the 4.5-6.5 Hz frequency range over frontal lobes. The power increase observed in controls carrying ε4 was significantly higher as compared with MCI non-carriers, while MCI carriers exhibited the highest relative power within the 4.5-6.5 Hz range. Higher power values within the low-frequency ranges correlated with a poorer cognitive performance in MCIs and controls. Our investigation demonstrates that APOEε4 affects resting-state activity to an extent that makes it more proximate to the pattern observed in early stages of AD. Therefore, a combination of genetic and neurophysiological information might help to detect MCI patients at higher risk of conversion to AD, and asymptomatic subjects at higher risk of developing a manifest cognitive deterioration.

  4. A case–control study on the effect of Apolipoprotein E genotypes on gastric cancer risk and progression

    PubMed Central

    2012-01-01

    Background Apolipoprotein E (ApoE) is a multifunctional protein playing both a key role in the metabolism of cholesterol and triglycerides, and in tissue repair and inflammation. The ApoE gene (19q13.2) has three major isoforms encoded by ε2, ε3 and ε4 alleles with the ε4 allele associated with hypercholesterolemia and the ε2 allele with the opposite effect. An inverse relationship between cholesterol levels and gastric cancer (GC) has been previously reported, although the relationship between apoE genotypes and GC has not been explored so far. Methods One hundred and fifty-six gastric cancer cases and 444 hospital controls were genotyped for apoE polymorphism (ε2, ε3, ε4 alleles). The relationship between GC and putative risk factors was measured using the adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) from logistic regression analysis. A gene-environment interaction analysis was performed. The effect of the apoE genotypes on survival from GC was explored by a Kaplan–Meier analysis and Cox proportional hazard regression model. Results Subjects carrying at least one apoE ε2 allele have a significant 60% decrease of GC risk (OR=0.40, 95% CI: 0.19 – 0.84) compared with ε3 homozygotes. No significant interaction emerged between the ε4 or ε2 allele and environmental exposures, nor ε2 or ε4 alleles affected the median survival times, even after correcting for age, gender and stadium. Conclusions Our study reports for the first time a protective effect of the ε2 allele against GC, that might be partly attributed to the higher antioxidant properties of ε2 compared with the ε3 or ε4 alleles. Given the study’s sample size, further studies are required to confirm our findings. PMID:23098561

  5. The endogenous estradiol metabolite 2-methoxyestradiol reduces atherosclerotic lesion formation in female apolipoprotein E-deficient mice.

    PubMed

    Bourghardt, Johan; Bergström, Göran; Krettek, Alexandra; Sjöberg, Sara; Borén, Jan; Tivesten, Asa

    2007-09-01

    Estradiol, the major endogenous estrogen, reduces experimental atherosclerosis and metabolizes to 2-methoxyestradiol in vascular cells. Currently undergoing evaluation in clinical cancer trials, 2-methoxyestradiol potently inhibits cell proliferation independently of the classical estrogen receptors. This study examined whether 2-methoxyestradiol affects atherosclerosis development in female mice. Apolipoprotein E-deficient mice, a well-established mouse model of atherosclerosis, were ovariectomized and treated through slow-release pellets with placebo, 17beta-estradiol (6 microg/d), or 2-methoxyestradiol [6.66 microg/d (low-dose) or 66.6 microg/d (high-dose)]. After 90 d, body weight gain decreased and uterine weight increased in the high-dose but not low-dose 2-methoxyestradiol group. En face analysis showed that the fractional area of the aorta covered by atherosclerotic lesions decreased in the high-dose 2-methoxyestradiol (52%) but not in the low-dose 2-methoxyestradiol group. Total serum cholesterol levels decreased in the high- and low-dose 2-methoxyestradiol groups (19%, P < 0.05 and 21%, P = 0.062, respectively). Estradiol treatment reduced the fractional atherosclerotic lesion area (85%) and decreased cholesterol levels (42%). In conclusion, our study shows for the first time that 2-methoxyestradiol reduces atherosclerotic lesion formation in vivo. The antiatherogenic activity of an estradiol metabolite lacking estrogen receptor activating capacity may argue that trials on cardiovascular effects of hormone replacement therapy should use estradiol rather than other estrogens. Future research should define the role of 2-methoxyestradiol as a mediator of the antiatherosclerotic actions of estradiol. Furthermore, evaluation of the effects of 2-methoxyestradiol on cardiovascular disease endpoints in ongoing clinical trials is of great interest.

  6. Is hyperuricemia a risk factor for arteriosclerosis? Uric acid and arteriosclerosis in apolipoprotein e-deficient mice.

    PubMed

    Wakuda, Hirokazu; Uchida, Shinya; Ikeda, Masahiko; Tabuchi, Masaki; Akahoshi, Yasumitsu; Shinozuka, Kazumasa; Yamada, Shizuo

    2014-01-01

    Although hyperlipidemia, high blood pressure, and diabetes increase the risk of arteriosclerosis, it is not clear whether hyperuricemia increases the risk of arteriosclerosis or not. We examined the effects of uric acid and curative drugs for hyperuricemia on atherosclerosis-susceptible C57BL/6J apolipoprotein E-deficient (apoE(-/-)) mice. Male apoE(-/-) mice (age: 6 weeks) were fed a normal diet (normal diet group) or a uric acid-enriched diet. Mice fed the uric acid-enriched diet were divided into three groups and administered a drinking vehicle (high uric acid diet group), allopurinol (20 mg·kg(-1)·d(-1)), or benzbromarone (20 mg·kg(-1)·d(-1)) for 10 weeks. Serum uric acid concentrations were higher in the high uric acid diet group than in the normal diet group, and concentrations in the allopurinol and benzbromarone groups were lower than in the high uric acid diet group. Serum total cholesterol and triglyceride levels were lower in the allopurinol group than in the high uric acid diet group. Oxidative stress was lower in the benzbromarone group than in the high uric acid diet group. Atherosclerotic lesion areas were smaller in the allopurinol and benzbromarone groups than in the high uric acid diet group. Thus, hyperuricemia may not be an independent risk factor for arteriosclerosis; however, the administration of allopurinol and benzbromarone prevented the development of atherosclerosis in apoE(-/-) mice fed a uric acid-enriched diet. The anti-atherosclerotic effect was in part due to lower total cholesterol and oxidative stress in the serum. Other possible mechanisms underlying this effect should be investigated.

  7. Complement Factor H Binds to Human Serum Apolipoprotein E and Mediates Complement Regulation on High Density Lipoprotein Particles.

    PubMed

    Haapasalo, Karita; van Kessel, Kok; Nissilä, Eija; Metso, Jari; Johansson, Tiira; Miettinen, Sini; Varjosalo, Markku; Kirveskari, Juha; Kuusela, Pentti; Chroni, Angelika; Jauhiainen, Matti; van Strijp, Jos; Jokiranta, T Sakari

    2015-11-27

    The alternative pathway of complement is an important part of the innate immunity response against foreign particles invading the human body. To avoid damage to host cells, it needs to be efficiently down-regulated by plasma factor H (FH) as exemplified by various diseases caused by mutations in its domains 19-20 (FH19-20) and 5-7 (FH5-7). These regions are also the main interaction sites for microbial pathogens that bind host FH to evade complement attack. We previously showed that inhibition of FH binding by a recombinant FH5-7 construct impairs survival of FH binding pathogens in human blood. In this study we found that upon exposure to full blood, the addition of FH5-7 reduces survival of, surprisingly, also those microbes that are not able to bind FH. This effect was mediated by inhibition of complement regulation and subsequently enhanced neutrophil phagocytosis by FH5-7. We found that although FH5-7 does not reduce complement regulation in the actual fluid phase of plasma, it reduces regulation on HDL particles in plasma. Using affinity chromatography and mass spectrometry we revealed that FH interacts with serum apolipoprotein E (apoE) via FH5-7 domains. Furthermore, binding of FH5-7 to HDL was dependent on the concentration of apoE on the HDL particles. These findings explain why the addition of FH5-7 to plasma leads to excessive complement activation and phagocytosis of microbes in full anticoagulated blood. In conclusion, our data show how FH interacts with apoE molecules via domains 5-7 and regulates alternative pathway activation on plasma HDL particles.

  8. Apolipoprotein E Genotype-Dependent Paradoxical Short-Term Effects of {sup 56}Fe Irradiation on the Brain

    SciTech Connect

    Haley, Gwendolen E.; Villasana, Laura; Dayger, Catherine; Davis, Matthew J.; Raber, Jacob

    2012-11-01

    Purpose: In humans, apolipoprotein E (apoE) is encoded by three major alleles ({epsilon}2, {epsilon}3, and {epsilon}4) and, compared to apoE3, apoE4 increases the risk of developing Alzheimer disease and cognitive impairments following various environmental challenges. Exposure to irradiation, including that of {sup 56}Fe, during space missions poses a significant risk to the central nervous system, and apoE isoform might modulate this risk. Methods and Materials: We investigated whether apoE isoform modulates hippocampus-dependent cognitive performance starting 2 weeks after {sup 56}Fe irradiation. Changes in reactive oxygen species (ROS) can affect cognition and are induced by irradiation. Therefore, after cognitive testing, we assessed hippocampal ROS levels in ex vivo brain slices, using the ROS-sensitive fluorescent probe, dihydroethidium (DHE). Brain levels of 3-nitrotyrosine (3-NT), CuZn superoxide dismutase (CuZnSOD), extracellular SOD, and apoE were assessed using Western blotting analysis. Results: In the water maze, spatial memory retention was impaired by irradiation in apoE2 and apoE4 mice but enhanced by irradiation in apoE3 mice. Irradiation reduced DHE-oxidation levels in the enclosed blade of the dentate gyrus and levels of 3-NT and CuZnSOD in apoE2 but not apoE3 or apoE4 mice. Finally, irradiation increased apoE levels in apoE3 but not apoE2 or apoE4 mice. Conclusions: The short-term effects of {sup 56}Fe irradiation on hippocampal ROS levels and hippocampus-dependent spatial memory retention are apoE isoform-dependent.

  9. All-trans retinoic acid can regulate the expressions of gelatinases and apolipoprotein E in glomerulosclerosis rats.

    PubMed

    Zhou, Tian-Biao; Qin, Yuan-Han; Ou, Chao; Lei, Feng-Ying; Su, Li-Na; Huang, Wei-Fang; Zhao, Yan-Jun

    2011-01-01

    Apolipoprotein E (apoE) is an important plasma protein in cholesterol homeostasis and plays a key role in the pathogenesis of glomerulosclerosis (GS). Gelatinases include matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). The abnormal expressions of gelatinases are implicated in the pathogenesis of extracellular matrix accumulation. All-trans retinoic acid (ATRA) is an import biological agent which can play a protective role against GS. We performed this investigation to explore whether ATRA could regulate the expressions of gelatinases and apoE in the glomerulus of GS rats. 120 Wistar rats were randomly divided into three groups: sham operation group (SHO), glomerulosclerosis model group without treatment (GS) and GS model group treated with ATRA (GA). The GS disease was established by uninephrectomy and adriamycin injection. At the end of 9 and 13 weeks, the relevant samples were collected and determined. Compared with GS group at 9/13 weeks, values of 24-hour urine total protein, 24-hour urine excretion for albumin, blood urea nitrogen, serum creatinine and glomerulosclerosis index, and protein expressions of apoE, transforming growth factor-βl (TGF-β1), α-smooth muscle actin, collagen-IV and fibronectin in glomerulus and mRNA expressions of apoE and TGF-β1 in renal tissue were significantly down-regulated by ATRA (each P<0.01). However, the expressions of MMP-2 and MMP-9 (mRNA, protein and activity) were enhanced in GA group than those in GS group. In conclusion, gelatinases are associated with apoE expression, and ATRA can increase the gelatinases expressions and reduce the accumulation of apoE in glomerulus of GS rats, but the detailed mechanism needs to be elucidated in the future.

  10. Apolipoprotein E inhibits toll-like receptor (TLR)-3- and TLR-4-mediated macrophage activation through distinct mechanisms.

    PubMed

    Zhu, Yanjuan; Kodvawala, Ahmer; Hui, David Y

    2010-04-28

    Previous studies have shown that apoE (apolipoprotein E) expression in macrophages suppresses inflammatory responses; however, whether endogenously synthesized apoE acts intracellularly or after its secretion in suppressing macrophage inflammation remains unclear. The present study used the murine monocyte macrophage cell line RAW 264.7 to examine the influence of exogenous apoE on macrophage inflammatory responses induced by TLR (Toll-like receptor)-4 and TLR-3 agonists LPS (lipopolysaccharide) and poly(I-C) respectively. Results showed that exogenously added apoE suppressed the LPS and poly(I-C) induction of IL (interleukin)-6, IL-1beta and TNF-alpha (tumour necrosis factor-alpha) secretion by RAW 264.7 cells. The mechanism was related to apoE suppression of TLR-agonist-induced phosphorylation of JNK (c-Jun N-terminal kinase) and c-Jun. A peptide containing the tandem repeat sequence of the receptor-binding domain of apoE, apoE-(141-155)2, was similarly effective in inhibiting LPS- and poly(I-C)-induced macrophage inflammatory responses. Reductive methylation of lysine residues in apoE, which abolished its receptor-binding capability without affecting its ability to interact with HSPGs (heparin sulfate proteoglycans), inhibited the ability of apoE to suppress macrophage responses to LPS, but had no effect on apoE suppression of poly(I-C)-induced macrophage activation. The ability of apoE to suppress poly(I-C)-induced pro-inflammatory cytokine production was abolished by heparinase treatment of RAW 264.7 cells to remove cell-surface HSPGs. Taken together, these results indicate that exogenous apoE inhibits macrophage inflammatory responses to TLR-4 and TLR-3 agonists through distinct mechanisms related to receptor and HSPG binding respectively, and that these inhibitory effects converged on suppression of JNK and c-Jun activation which are necessary for macrophage activation.

  11. Apolipoprotein E (APOE) genotype has dissociable effects on memory and attentional-executive network function in Alzheimer's disease.

    PubMed

    Wolk, David A; Dickerson, Bradford C

    2010-06-01

    The epsilon4 allele of the apolipoprotein E (APOE) gene is the major genetic risk factor for Alzheimer's disease (AD), but limited work has suggested that APOE genotype may modulate disease phenotype. Carriers of the epsilon4 allele have been reported to have greater medial temporal lobe (MTL) pathology and poorer memory than noncarriers. Less attention has focused on whether there are domains of cognition and neuroanatomical regions more affected in noncarriers. Further, a major potential confound of prior in vivo studies is the possibility of different rates of clinical misdiagnosis for carriers vs. noncarriers. We compared phenotypic differences in cognition and topography of regional cortical atrophy of epsilon4 carriers (n = 67) vs. noncarriers (n = 24) with mild AD from the Alzheimer's Disease Neuroimaging Initiative, restricted to those with a cerebrospinal fluid (CSF) molecular profile consistent with AD. Between-group comparisons were made for psychometric tests and morphometric measures of cortical thickness and hippocampal volume. Carriers displayed significantly greater impairment on measures of memory retention, whereas noncarriers were more impaired on tests of working memory, executive control, and lexical access. Consistent with this cognitive dissociation, carriers exhibited greater MTL atrophy, whereas noncarriers had greater frontoparietal atrophy. Performance deficits in particular cognitive domains were associated with disproportionate regional brain atrophy within nodes of cortical networks thought to subserve these cognitive processes. These convergent cognitive and neuroanatomic findings in individuals with a CSF molecular profile consistent with AD support the hypothesis that APOE genotype modulates the clinical phenotype of AD through influence on specific large-scale brain networks.

  12. CEREBRAL ATROPHY, APOLIPOPROTEIN E ε4, AND RATE OF DECLINE IN EVERYDAY FUNCTION AMONG PATIENTS WITH AMNESTIC MILD COGNITIVE IMPAIRMENT

    PubMed Central

    Okonkwo, Ozioma C.; Alosco, Michael L.; Jerskey, Beth A.; Sweet, Lawrence H.; Ott, Brian R.; Tremont, Geoffrey

    2010-01-01

    BACKGROUND Patients with amnestic mild cognitive impairment (MCI) demonstrate decline in everyday function. In this study, we investigated whether whole brain atrophy and apolipoprotein E (APOE) genotype are associated with the rate of functional decline in MCI. METHODS Participants were 164 healthy controls, 258 MCI patients, and 103 patients with mild Alzheimer’s disease (AD), enrolled in the Alzheimer’s Disease Neuroimaging Initiative (ADNI). They underwent brain MRI scans, APOE genotyping, and completed up to 6 biannual Functional Activities Questionnaire (FAQ) assessments. Random effects regressions were used to examine trajectories of decline in FAQ across diagnostic groups, and to test the effects of ventricle-to-brain ratio (VBR) and APOE genotype on FAQ decline among MCI patients. RESULTS Rate of decline in FAQ among MCI patients was intermediate between that of controls and mild AD patients. Patients with MCI who converted to mild AD declined faster than those who remained stable. Among MCI patients, increased VBR and possession of any APOE ε4 allele were associated with faster rate of decline in FAQ. In addition, there was a significant VBR by APOE ε4 interaction such that patients who were APOE ε4 positive and had increased atrophy experienced the fastest decline in FAQ. CONCLUSIONS Functional decline occurs in MCI, particularly among patients who progress to mild AD. Brain atrophy and APOE ε4 positivity are associated with such declines, and patients who have elevated brain atrophy and are APOE ε4 positive are at greatest risk of functional degradation. These findings highlight the value of genetic and volumetric MRI information as predictors of functional decline, and thus disease progression, in MCI. PMID:20813341

  13. Apolipoprotein E receptor-2 (ApoER2) mediates selenium uptake from selenoprotein P by the mouse testis.

    PubMed

    Olson, Gary E; Winfrey, Virginia P; Nagdas, Subir K; Hill, Kristina E; Burk, Raymond F

    2007-04-20

    Selenium is a micronutrient that is essential for the production of normal spermatozoa. The selenium-rich plasma protein selenoprotein P (Sepp1) is required for maintenance of testis selenium and for fertility of the male mouse. Sepp1 trafficking in the seminiferous epithelium was studied using conventional methods and mice with gene deletions. Immunocytochemistry demonstrated that Sepp1 is present in vesicle-like structures in the basal region of Sertoli cells, suggesting that the protein is taken up intact. Sepp1 affinity chromatography of a testicular extract followed by mass spectrometry-based identification of bound proteins identified apolipoprotein E receptor 2 (ApoER2) as a candidate testis Sepp1 receptor. In situ hybridization analysis identified Sertoli cells as the only cell type in the seminiferous epithelium with detectable ApoER2 expression. Testis selenium levels in apoER2(-/-) males were sharply reduced from those in apoER2(+/+) males and were comparable with the depressed levels found in Sepp1(-/-) males. However, liver selenium levels were unchanged by deletion of apoER2. Immunocytochemistry did not detect Sepp1 in the Sertoli cells of apoER2(-/-) males, consistent with a defect in the receptor-mediated Sepp1 uptake pathway. Phase contrast microscopy revealed identical sperm defects in apoER2(-/-) and Sepp1(-/-) mice. Co-immunoprecipitation analysis demonstrated an interaction of testis ApoER2 with Sepp1. These data demonstrate that Sertoli cell ApoER2 is a Sepp1 receptor and a component of the selenium delivery pathway to spermatogenic cells.

  14. Cytochrome P450 1B1 Contributes to the Development of Atherosclerosis and Hypertension in Apolipoprotein E-Deficient Mice.

    PubMed

    Song, Chi Young; Ghafoor, Khuzema; Ghafoor, Hafiz U; Khan, Nayaab S; Thirunavukkarasu, Shyamala; Jennings, Brett L; Estes, Anne M; Zaidi, Sahar; Bridges, Dave; Tso, Patrick; Gonzalez, Frank J; Malik, Kafait U

    2016-01-01

    Cytochrome P450 (CYP) 1B1 contributes to vascular smooth muscle cell growth and hypertension in male mice. This study was conducted to determine the contribution of CYP1B1 to the development of atherosclerosis and hypertension and associated pathogenesis in 8-week-old male apolipoprotein E-deficient (ApoE(-/-)/Cyp1b1(+/+)), and ApoE- and CYP1B1-deficient (ApoE(-/-)/Cyp1b1(-/-)) mice fed a normal or atherogenic diet for 12 weeks. A separate group of ApoE(-/-)/Cyp1b1(+/+) mice on an atherogenic diet was injected every third day with the CYP1B1 inhibitor, 2,3',4,5'-tetramethoxystilbene (300 μg/kg), or its vehicle, dimethyl sulfoxide (30 μL, IP); systolic blood pressure was measured by the tail cuff method. After 12 weeks, mice were euthanized, blood collected for lipid analysis, and aortas harvested for measuring lesions and remodeling, and for infiltration of inflammatory cells by histological and immunohistochemical analysis, respectively, and for reactive oxygen species production. Blood pressure, areas of lipids and collagen deposition, elastin breaks, infiltration of macrophages and T lymphocytes, reactive oxygen species generation in the aorta, and plasma lipid levels were increased in ApoE(-/-)/Cyp1b1(+/+) mice on an atherogenic diet; these changes were minimized in mice given 2,3',4,5'-tetramethoxystilbene, and in ApoE(-/-)/Cyp1b1(-/-) mice on an atherogenic diet; absorption/production of lipids remained unaltered in these mice. These data suggest that aortic lesions, hypertension, and associated pathogenesis in ApoE(-/-)/Cyp1b1(+/+) mice on an atherogenic diet are most likely dependent on CYP1B1-generated oxidative stress and increased plasma lipid levels independent of blood pressure and absorption of lipids. CYP1B1 could serve as a novel target for developing drugs to treat atherosclerosis and hypertension caused by hypercholesterolemia.

  15. An efficient on-column expressed protein ligation strategy: Application to segmental triple labeling of human apolipoprotein E3

    PubMed Central

    Zhao, Wentao; Zhang, Yonghong; Cui, Chunxian; Li, Qianqian; Wang, Jianjun

    2008-01-01

    Expressed protein ligation (EPL) is an intein-based approach that has been used for protein engineering and biophysical studies of protein structures. One major problem of the EPL is the low yield of final ligation product, primarily due to the complex procedure of the EPL, preventing EPL from gaining popularity in the research community. Here we report an efficient on-column EPL strategy, which focuses on enhancing the expression level of the intein-fusion protein that generates thioester for the EPL. We applied this EPL strategy to human apolipoprotein E (apoE) and routinely obtained 25–30 mg segmental, triple-labeled apoE from 1-L cell culture. The approaches reported here are general approaches that are not specific for apoE, thus providing a general strategy for a highly efficient EPL. In addition, we also report an isotopic labeling scheme that double-labels one domain and keeps the other domain of apoE deuterated. Such an isotopic labeling scheme can only be achieved using the EPL strategy. Our data indicated that the segmental triple-labeled apoEs using this labeling scheme produced high-quality, simplified NMR spectra, facilitating NMR spectral assignment. For large proteins, such as apoE, perdeuterated protein samples have to be used to reduce the linewidth of NMR signals, causing a major problem for the NOE-based NMR method, since perdeuterated proteins lack protons for NOE measurement. The new labeling strategy solves this problem and provides 13C/15N double-labeled, protonated protein domains, allowing for determination of high-resolution NMR structure of these large proteins. PMID:18305193

  16. A systematic review and meta-analysis of the association between the apolipoprotein E genotype and delirium.

    PubMed

    Adamis, Dimitrios; Meagher, David; Williams, John; Mulligan, Owen; McCarthy, Geraldine

    2016-04-01

    The role of apolipoprotein E (APOE) in Alzheimer's disease and other dementias has been investigated intensively. However, the relationship between APOE and delirium has only recently been explored in studies that have included relatively small samples. A meta-analysis of the published pooled data is timely to explore the relationship between APOE and delirium and to inform further research in this topic. PubMed, EBSCOhost, Google Scholar, Scopus, all EBM Reviews (OVID) and the Cochrane Database of Systematic Reviews were searched with relevant keywords and from the references of relevant papers. Ten papers were found that examined the relationship between APOE and delirium. Data were extracted from eight of them and pooled for meta-analysis using random effects with R software. Data from 1762 participants, of whom 479 (27.2%) were diagnosed with delirium, showed low heterogeneity (Q=13.11, d.f.=7, P=0.07; I=44.86%). The possession of the APOE ε4 allele has a small (log odds ratio: 0.18, 95% confidence interval: 0.23-0.59), nonsignificant (P=0.38) effect on the presence of delirium. No publication bias was identified. The metapower of the pooled data was low (α=0.05, power=0.65). On analysing the studies to date, it seems that there is no association between APOE and the occurrence of delirium. We suggest that further studies are needed with greater number of patients to clarify any association as well as to examine for other patterns of association including relevance for subgroups of patients who develop delirium and for effects on the phenotype of delirium and the outcomes.

  17. Aronia melanocarpa (chokeberry) polyphenol-rich extract improves antioxidant function and reduces total plasma cholesterol in apolipoprotein E knockout mice.

    PubMed

    Kim, Bohkyung; Ku, Chai Siah; Pham, Tho X; Park, Youngki; Martin, Derek A; Xie, Liyang; Taheri, Rod; Lee, Jiyoung; Bolling, Bradley W

    2013-05-01

    We hypothesized that a polyphenol-rich chokeberry extract (CBE) would modulate hepatic lipid metabolism and improve antioxidant function in apolipoprotein E knockout (apoE(-/-)) mice. ApoE(-/-) mice were fed diets containing 15% fat with 0.2% cholesterol alone or supplemented with 0.005% or 0.05% CBE for 4 weeks. CBE polyphenol content was determined by the total phenols, 4-dimethylaminocinnamaldehyde, and ultra high-performance liquid chromatography-mass spectrometry methods. The 0.05% CBE diet provided mice with mean daily doses of 1.2 mg gallic acid equivalents of total phenols, 0.19 mg anthocyanins, 0.17 mg phenolic acids, 0.06 mg proanthocyanidins (as catechin-equivalents), and 0.02 mg flavonols. The 0.05% CBE group had 12% less plasma total cholesterol concentrations than the control. Despite the hypocholesterolemic effect of CBE, hepatic mRNA levels of low-density lipoprotein receptor, hydroxyl-3-methylglutaryl coenzyme A reductase and cholesterol 7α-hydroxylase in CBE-fed mice were not significantly different from controls. Dietary CBE did not alter hepatic lipid content or the hepatic expression of genes involved in lipogenesis and fatty acid β-oxidation such as fatty acid synthase, carnitine palmitoyltransferase 1 and acyl-CoA oxidase. Plasma paraoxonase and catalase activities were significantly increased in mice fed 0.05% CBE. Both CBE diets increased hepatic glutathione peroxidase (GPx) activity but the 0.05% CBE group had 24% less proximal intestine GPx activity relative to controls. Thus, dietary CBE lowered total cholesterol and improved plasma and hepatic antioxidant function at nutritionally-relevant doses in apoE(-/-) mice. Furthermore, the CBE cholesterol-lowering mechanism in apoE(-/-) mice was independent of hepatic expression of genes involved in cholesterol metabolism.

  18. Rapid detection of apolipoprotein E genotypes in Alzheimer's disease using polymerase chain reaction-single strand conformation polymorphism.

    PubMed

    Kamruecha, Worawan; Chansirikarnjana, Sirintorn; Nimkulrat, Ekapot; Udommongkol, Chesda; Wongmek, Wanna; Thangnipon, Wipawan

    2006-07-01

    Apolipoprotein E (APOE) gene on chromosome 19q13.2 is encoded by three common alleles designated as epsilon2, epsilon3 and epsilon4. In Alzheimer's disease (AD) the epsilon4 allele is over-represented and is considered to be a major genetic risk factor. Several methods have been developed to determine APOE genotypes. Among them, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) appears to be highly reliable. In this study, we improved the nonisotopic PCR-SSCP method for determining APOE genotypes in 42 cases of AD patients, 40 cases of non-AD dementia patients, and 49 cases of age-matched controls. DNA from the target sequence on APOE was amplified by PCR from peripheral blood genomic DNA. PCR products were electrophoresed in a non-denaturing polyacrylamide gel and visualized by silver staining. We found that the epsilon4 allele had a significantly high frequency of occurrence in AD patients (33.3%) compared with age-matched controls (13.3%) (chi(2) = 10.43, p = 0.001) and non-AD dementia (10%) (chi(2) = 13.02, p<0.001) whereas the epsilon3 allele was of high frequency in non-AD dementia (90%) compared with age-matched controls (85.7%) and AD patients (66.7%). APOE epsilon4 homozygotes were found only in AD groups. On the other hand, the epsilon2 allele was found only in an age-matched control. This study confirmed that the APOE psilon4 allele is a risk factor in Thai AD subjects and that the PCR-SSCP method is a rapid and useful means of detecting the APOE genotype in AD.

  19. Prenatal stress enhances severity of atherosclerosis in the adult apolipoprotein E-deficient mouse offspring via inflammatory pathways.

    PubMed

    Ho, H; Lhotak, S; Solano, M E; Karimi, K; Pincus, M K; Austin, R C; Arck, P

    2013-02-01

    Atherosclerosis is the underlying cause of cardiovascular disease and stroke. Endothelial cell dysfunctions are early events in atherosclerosis, resulting in the recruitment of circulating monocytes. The immune system can elicit an inflammatory response toward the atherosclerotic lesion, thereby accelerating lesion growth. Risk factors for atherosclerosis include hypertension, smoking, stress perception or low birth weight. As prenatal stress challenge decreases the birth weight and affects the offspring's postnatal immune response, we aimed to investigate whether prenatal stress contributes to the development of atherosclerosis in mice. Syngenic pregnant apolipoprotein E-deficient (apoE-/-) dams were exposed to sound stress on gestation days 12.5 and 14.5. The presence and size of atherosclerotic plaques in the offspring at the age of 15 weeks was evaluated by histomorphology, accompanied by flow cytometric analysis of the frequency and phenotype of monocytes/macrophages and regulatory T (Treg) cells in the blood. Further, cytokine secretion of peripheral blood lymphocytes was analyzed. In response to prenatal stress challenge, an increased frequency of large atherosclerotic plaques was detectable in apoE-/- offspring, which was particularly profound in females. Prenatal stress also resulted in alterations of the offspring's immune response, such as a decreased frequency of Treg cells in blood, alterations of macrophage populations in blood and an increased secretion of inflammatory cytokines. We provide novel evidence that prenatally stressed adult offspring show an increased severity of atherosclerosis. As Treg cells are key players in dampening inflammation, the observed increase in atherosclerosis may be due to the lack of Treg cell frequency. Future interdisciplinary research is urgently required to understand the developmental origin of prenatal stress-induced atherosclerosis. The availability of our model may facilitate and foster such research endeavors.

  20. Atorvastatin Upregulates the Expression of miR-126 in Apolipoprotein E-knockout Mice with Carotid Atherosclerotic Plaque.

    PubMed

    Pan, Xudong; Hou, Rongyao; Ma, Aijun; Wang, Ting; Wu, Mei; Zhu, Xiaoyan; Yang, Shaonan; Xiao, Xing

    2017-01-01

    Carotid atherosclerosis (AS) is a chronic inflammatory disease of the carotid arterial wall, which is very important in terms of the occurrence of cerebral vascular accidents. Studies have demonstrated that microRNAs (miRNAs) and their target genes are involved in the formation of atherosclerosis and that atorvastatin might reduce atherosclerotic plaques by regulating the expression of miRNAs. However, the related mechanism is not yet known. In this study, we first investigated the effects of atorvastatin on miR-126 and its target gene, i.e., vascular cell adhesion molecule-1 (VCAM-1) in apolipoprotein E-knockout (ApoE-/-) mice with carotid atherosclerotic plaque in vivo. We compared the expressions of miR-126 and VCAM-1 between the control, atherosclerotic model and atorvastatin treatment groups of ApoE-/- mice using RT-PCR and Western blot. We found the miR-126 expression was significantly down-regulated, and the VCAM-1 expression was significantly up-regulated in the atherosclerotic model group, which accelerated the progression of atherosclerosis in the ApoE-/- mice. These results following atorvastatin treatment indicated that miR-126 expression was significantly up-regulated, VCAM-1 expression was significantly down-regulated and atherosclerotic lesions were reduced. The present results might explain the mechanism by which miR-126 is involved in the formation of atherosclerosis in vivo. Our study first indicated that atorvastatin might exert its anti-inflammatory effects in atherosclerosis by regulating the expressions of miR-126 and VCAM-1 in vivo.

  1. Metformin reduces the endotoxin-induced down-regulation of apolipoprotein E gene expression in macrophages

    SciTech Connect

    Stavri, Simona; Trusca, Violeta G.; Simionescu, Maya; Gafencu, Anca V.

    2015-05-29

    The atheroprotective role of macrophage-derived apolipoprotein E (apoE) is well known. Our previous reports demonstrated that inflammatory stress down-regulates apoE expression in macrophages, aggravating atherogenesis. Metformin, extensively used as an anti-diabetic drug, has also anti-inflammatory properties, and thus confers vascular protection. In this study, we questioned whether metformin could have an effect on apoE expression in macrophages in normal conditions or under lipopolysaccharide (LPS)-induced stress. The results showed that metformin slightly increases the apoE expression only at high doses (5–10 mM). Low doses of metformin (1–3 mM) significantly reduce the LPS down-regulatory effect on apoE expression in macrophages. Our experiments demonstrated that LPS-induced NF-κB binds to the macrophage-specific distal regulatory element of apoE gene, namely to the multienhancer 2 (ME.2) and its 5′-deletion fragments. The NF-κB binding on ME.2 and apoE promoter has a down-regulatory effect. In addition, data revealed that metformin impairs NF-κB nuclear translocation, and thus, improves the apoE levels in macrophages under inflammatory stress. The positive effect of metformin in the inflammatory states, its clinical safety and low cost, make this drug a potential adjuvant in the therapeutic strategies for atherosclerosis. - Highlights: • High doses of metformin slightly increase apoE expression in macrophages. • Low doses of metformin up-regulate apoE gene in endotoxin-stressed macrophages. • Metformin reduces the negative effect of LPS on apoE expression by NF-κB inhibition.

  2. Preclinical cognitive decline in late middle-aged asymptomatic apolipoprotein E-e4/4 homozygotes: a replication study.

    PubMed

    Caselli, R J; Osborne, D; Reiman, E M; Hentz, J G; Barbieri, C J; Saunders, A M; Hardy, J; Graff-Radford, N R; Hall, G R; Alexander, G E

    2001-08-15

    In a previous cross-sectional study of 100 asymptomatic individuals aged 49-69, we reported age-related decline in immediate and delayed memory that was steeper in apolipoprotein E (apoE)-e4/4 homozygotes than in members of other genetic subgroups. These findings were preliminarily based upon the statistical problem of multiple comparisons. We therefore sought to replicate these findings in a new cohort. From 1998 to 2000, 80 asymptomatic residents of Maricopa County, AZ were recruited through newspaper ads. 20 apoE-e4/4 homozygotes, 20 e3/4 heterozygotes, and 40 e4 noncarriers were matched (1:1:2) by age, gender, and years of education. All had normal neurologic and psychiatric examinations, including Folstein minimental status exam (MMSE) and Hamilton depression scale, and underwent a battery of neuropsychological tests identical to those in our previous study. The groups were well-matched for age (55.9+/-5.9 years), gender (60% women), and education (15.9+/-2.2 years), and were demographically similar to our previous cohort. Complex figure test recall was lower in e3/4 heterozygotes than noncarriers, but there was no significant difference between e4/4 homozygotes and noncarriers. There were no other significant differences in mean test scores between groups, but Wechsler adult intelligence scale-revised (WAIS-R) digit span showed a significant negative correlation with age in the e4/4 homozygote group relative to e4 noncarriers (p=0.008) as we had found in our previous study. In conclusion, we found a significant negative correlation of WAIS-R digit span with age in apoE-e4/4 homozygotes relative to e4 noncarriers in two separate cohorts, possibly reflecting an age-related effect on frontal lobe function in this genetic subgroup.

  3. Apolipoprotein E gene variants as a risk factor for coronary artery disease in type 2 diabetic Egyptian patients.

    PubMed

    Halim, Emad F Abd El; Reda, Ahmed A; Hendi, Amera A K; Zaki, Seham A; Essa, Enas S; Khalifa, Amani S

    2012-01-01

    Patients with diabetes mellitus (DM) have increased mortality and morbidity of cardiovascular diseases compared with non-diabetic patients. The role of apolipoprotain E in lipid metabolism and cholesterol transport is well established. Apolipoprotein E gene (APO E) polymprphism that confers susceptibility to or protection from CAD in patients with type 2 DM may be quite different in different ethnic populations. We aimed to determine the frequencies of allelic variants of APO E in Egyptian population and to examine the relationship between APO E polymorphism and risk of coronary artery disease (CAD) in Egyptian type 2 diabetic patients. The study included 35 diabetic patients with CAD (group 1), 35 diabetic patients without CAD (group II) and 30 control subjects. All were subjected to history taking, clinical examination, and laboratory investigations for lipid profile and APO E genotyping by PCR-RFLP. Results revealed that epsilon3 allele was the commonest among the studied subjects (84%). The frequencies of epsilon2 and epsilon4 alleles were higher in group I (24.3% and 8.6% respectively) than group II and controls. The frequency of E2/E2, E2/E3, and E4/E3 genotypes was significantly higher in group I than group II and controls. Comparing group I vs. controls and group I vs. group II, multivariate analysis demonstrated significantly increased risk for CAD with epsilon4 and epsilon2 alleles vs. E3 (OR=7.02 and 4.97 respectively). In Conclusion, epsilon4 and E2 alleles are associated with higher risk of CAD in type2 DM than epsilon3 allele. Larger scale studies are still needed to either confirm or modify these results.

  4. Apolipoprotein E (APOE) genotype has dissociable effects on memory and attentional–executive network function in Alzheimer’s disease

    PubMed Central

    Wolk, David A.; Dickerson, Bradford C.; Weiner, Michael; Aiello, Marilyn; Aisen, Paul; Albert, Marilyn S.; Alexander, Gene; Anderson, Heather S.; Anderson, Karen; Apostolova, Liana; Arnold, Steve; Ashford, Wes; Assaly, Michele; Asthana, Sanjay; Bandy, Dan; Bartha, Rob; Bates, Vernice; Beckett, Laurel; Bell, Karen L.; Benincasa, Amanda L.; Bergman, Howard; Bernick, Charles; Bernstein, Matthew; Black, Sandra; Blank, Karen; Borrie, Michael; Brand, Connie; Brewer, James; Brown, Alice D.; Burns, Jeffrey M.; Cairns, Nigel J.; Caldwell, Curtis; Capote, Horacio; Carlsson, Cynthia M.; Carmichael, Owen; Cellar, Janet S.; Celmins, Dzintra; Chen, Kewei; Chertkow, Howard; Chowdhury, Munir; Clark, David; Connor, Donald; Correia, Stephen; Crawford, Karen; Dale, Anders; de Leon, Mony J; De Santi, Susan M; DeCarli, Charles; deToledo-Morrell, Leyla; DeVous, Michael; Diaz-Arrastia, Ramon; Dolen, Sara; Donohue, Michael; Doody, Rachelle S.; Doraiswamy, P. Murali; Duara, Ranjan; Englert, Jessica; Farlow, Martin; Feldman, Howard; Felmlee, Joel; Fleisher, Adam; Fletcher, Evan; Foroud, Tatiana M.; Foster, Norm; Fox, Nick; Frank, Richard; Gamst, Anthony; Given, Curtis A.; Graff-Radford, Neill R; Green, Robert C.; Griffith, Randall; Grossman, Hillel; Hake, Ann M.; Hardy, Peter; Harvey, Danielle; Heidebrink, Judith L.; Hendin, Barry A.; Herring, Scott; Honig, Lawrence S.; Hosein, Chris; Robin Hsiung, Ging-Yuek; Hudson, Leon; Ismail, M. Saleem; Jack, Clifford R.; Jacobson, Sandra; Jagust, William; Jayam-Trouth, Annapurni; Johnson, Kris; Johnson, Heather; Johnson, Nancy; Johnson, Kathleen; Johnson, Keith A.; Johnson, Sterling; Kachaturian, Zaven; Karlawish, Jason H.; Kataki, Maria; Kaye, Jeffrey; Kertesz, Andrew; Killiany, Ronald; Kittur, Smita; Koeppe, Robert A.; Korecka, Magdalena; Kornak, John; Kozauer, Nicholas; Lah, James J.; Laubinger, Mary M.; Lee, Virginia M.-Y.; Lee, T.-Y.; Lerner, Alan; Levey, Allan I.; Longmire, Crystal Flynn; Lopez, Oscar L.; Lord, Joanne L.; Lu, Po H.; MacAvoy, Martha G.; Malloy, Paul; Marson, Daniel; Martin-Cook, Kristen; Martinez, Walter; Marzloff, George; Mathis, Chet; Mc-Adams-Ortiz, Catherine; Mesulam, Marsel; Miller, Bruce L.; Mintun, Mark A.; Mintzer, Jacobo; Molchan, Susan; Montine, Tom; Morris, John; Mulnard, Ruth A.; Munic, Donna; Nair, Anil; Neu, Scott; Nguyen, Dana; Norbash, Alexander; Oakley, MaryAnn; Obisesan, Thomas O.; Ogrocki, Paula; Ott, Brian R.; Parfitt, Francine; Pawluczyk, Sonia; Pearlson, Godfrey; Petersen, Ronald; Petrella, Jeffrey R.; Potkin, Steven; Potter, William Z.; Preda, Adrian; Quinn, Joseph; Rainka, Michelle; Reeder, Stephanie; Reiman, Eric M.; Rentz, Dorene M.; Reynolds, Brigid; Richard, Jennifer; Roberts, Peggy; Rogers, John; Rosen, Allyson; Rosen, Howard J.; Rusinek, Henry; Sabbagh, Marwan; Sadowsky, Carl; Salloway, Stephen; Santulli, Robert B.; Saykin, Andrew J.; Scharre, Douglas W.; Schneider, Lon; Schneider, Stacy; Schuff, Norbert; Shah, Raj C.; Shaw, Les; Shen, Li; Silverman, Daniel H.S.; Simpson, Donna M.; Sink, Kaycee M.; Smith, Charles D.; Snyder, Peter J.; Spann, Bryan M.; Sperling, Reisa A.; Spicer, Kenneth; Stefanovic, Bojana; Stern, Yaakov; Stopa, Edward; Tang, Cheuk; Tariot, Pierre; Taylor-Reinwald, Lisa; Thai, Gaby; Thomas, Ronald G.; Thompson, Paul; Tinklenberg, Jared; Toga, Arthur W.; Tremont, Geoffrey; Trojanowki, J.Q.; Trost, Dick; Turner, Raymond Scott; van Dyck, Christopher H.; Vanderswag, Helen; Varon, Daniel; Villanueva-Meyer, Javier; Villena, Teresa; Walter, Sarah; Wang, Paul; Watkins, Franklin; Weiner, Michael; Williamson, Jeff D.; Wolk, David; Wu, Chuang-Kuo; Zerrate, Maria; Zimmerman., Earl A.

    2010-01-01

    The ε4 allele of the apolipoprotein E (APOE) gene is the major genetic risk factor for Alzheimer’s disease (AD), but limited work has suggested that APOE genotype may modulate disease phenotype. Carriers of the ε4 allele have been reported to have greater medial temporal lobe (MTL) pathology and poorer memory than noncarriers. Less attention has focused on whether there are domains of cognition and neuroanatomical regions more affected in noncarriers. Further, a major potential confound of prior in vivo studies is the possibility of different rates of clinical misdiagnosis for carriers vs. noncarriers. We compared phenotypic differences in cognition and topography of regional cortical atrophy of ε4 carriers (n = 67) vs. noncarriers (n = 24) with mild AD from the Alzheimer’s Disease Neuroimaging Initiative, restricted to those with a cerebrospinal fluid (CSF) molecular profile consistent with AD. Between-group comparisons were made for psychometric tests and morphometric measures of cortical thickness and hippocampal volume. Carriers displayed significantly greater impairment on measures of memory retention, whereas noncarriers were more impaired on tests of working memory, executive control, and lexical access. Consistent with this cognitive dissociation, carriers exhibited greater MTL atrophy, whereas noncarriers had greater frontoparietal atrophy. Performance deficits in particular cognitive domains were associated with disproportionate regional brain atrophy within nodes of cortical networks thought to subserve these cognitive processes. These convergent cognitive and neuroanatomic findings in individuals with a CSF molecular profile consistent with AD support the hypothesis that APOE genotype modulates the clinical phenotype of AD through influence on specific large-scale brain networks. PMID:20479234

  5. A differential association of Apolipoprotein E isoforms with the Aβ oligomer in solution

    PubMed Central

    Petrlova, Jitka; Hong, Hyun-Seok; Bricarello, Daniel; Harishchandra, Ghimire; Lorigan, Gary; Jin, Lee-Way; Voss, John C.

    2010-01-01

    The molecular pathogenesis of disorders arising from protein mis-folding and aggregation is difficult to elucidate, involving a complex ensemble of intermediates whose toxicity depends upon their state of progression along distinct processing pathways. To address the complex mis-folding and aggregation that initiates the toxic cascade resulting in Alzheimer's disease, we have developed a TOAC spin-labeled Aβ peptide to observe its isoform-dependent interaction with the apoE protein. While most individuals carry the E3 isoform of apoE, approximately 15% of humans carry the E4 isoform, which is recognized as the most significant genetic determinant for Alzheimer's. ApoE is consistently associated with the amyloid plaque marker for Alzheimer's disease. A vital question centers on the influence of the two predominant isoforms, E3 and E4, on Aβ peptide processing and hence Aβ toxicity. We employed EPR spectroscopy of incorporated spin labels to investigate the interaction of apoE with the toxic oligomeric species of Aβ in solution. EPR spectra of the spin labeled side chain report on side chain and backbone dynamics, as well as the spatial proximity of spins in an assembly. Our results indicate oligomer binding involves the C-terminal domain of apoE, with apoE3 reporting a much greater response through this conformational marker. Coupled with SPR binding measurements, apoE3 displays a higher affinity and capacity for the toxic Aβ oligomer. These findings support the hypothesis that apoE polymorphism and Alzheimer's risk can largely be attributed to the reduced ability of apoE4 to function as a clearance vehicle for the toxic form of Aβ. PMID:21069870

  6. The intravenous injection of oxidized LDL- or Apolipoprotein B100 – Coupled splenocytes promotes Th1 polarization in wildtype and Apolipoprotein E – Deficient mice

    SciTech Connect

    Steinmetz, Martin; Ponnuswamy, Padmapriya; Laurans, Ludivine; Esposito, Bruno; Tedgui, Alain; Mallat, Ziad

    2015-08-14

    Background: Th1 responses in atherosclerosis are mainly associated with the aggravation of atherosclerotic plaques, whereas Th2 responses lead to a less pronounced disease in mouse models. The fixation of antigens on cells by means of ethylene carbodiimide (ECDI), and subsequent injection of these antigen-coupled splenocytes (Ag-SP) to induce tolerance against the attached antigens, has been successfully used to treat murine type 1 diabetes or encephalomyelitis in. We analyzed this approach in a mouse model for atherosclerosis. Methods and results: OTII-transgenic mice that were treated with a single dose of 5 × 10{sup 7} OVA-coupled splenocytes (OVA-SP), had decreased splenocyte proliferation, and lower IFNγ production in vitro upon antigen recall. However, in vivo CD4 cell activation was increased. To try lipoprotein-derived, “atherosclerosis-associated” antigens, we first tested human oxidized LDL. In wild type mice, an increase of IFNγ production upon in vitro recall was detected in the oxLDL-SP group. In Apolipoprotein E − deficient (ApoE−/−) mice that received oxLDL-SP every 5 weeks for 20 weeks, we did not find any difference of atherosclerotic plaque burden, but again increased IFNγ production. To overcome xenogenous limitations, we then examined the effects of mouse Apolipoprotein B100 peptides P3 and P6. ApoB100-SP treatment again promoted a more IFNγ pronounced response upon in vitro recall. Flow cytometry analysis of cytokine secreting spleen cells revealed CD4 positive T cells to be mainly the source for IFNγ. In ApoE−/− mice that were administered ApoB100-SP during 20 weeks, the atherosclerotic plaque burden in aortic roots as well as total aorta was unchanged compared to PBS treated controls. Splenocyte proliferation upon antigen recall was not significantly altered in ApoB100-SP treated ApoE−/− mice. Conclusion: Although we did not observe a relevant anti-atherosclerotic benefit, the treatment with antigen

  7. Low-density lipoprotein receptor-mediated delivery of a lipophilic daunorubicin derivative to B16 tumours in mice using apolipoprotein E-enriched liposomes.

    PubMed Central

    Versluis, A. J.; Rensen, P. C.; Rump, E. T.; Van Berkel, T. J.; Bijsterbosch, M. K.

    1998-01-01

    Many tumours express relatively high levels of low-density lipoprotein (LDL) receptors on their membranes. The LDL receptor is, therefore, an attractive target for the selective delivery of antineoplastic drugs to tumour cells. We reported previously on the synthesis of small apolipoprotein E (apoE)-containing liposomes that behave in vivo in a very similar way to native LDL. In this study, we examined the interaction of this liposomal carrier with cultured B16 melanoma cells. Binding of apoE liposomes to the cells is saturable, with a maximum binding of approximately 90000 particles per cell. Cross-competition studies indicated that apoE liposomes are bound by the LDL receptor. Association of apoE liposomes to B16 cells is strictly Ca2+ dependent, which forms additional evidence for a role of the LDL receptor. The affinity of apoE liposomes for the LDL receptor on B16 cells is 15-fold higher than that of LDL (0.77 vs 11.5 nM respectively). ApoE is essential for the LDL receptor recognition because liposomes lacking apoE were, in competition studies, 20- to 50-fold less effective than apoE-containing liposomes. We examined in B16 tumour-bearing mice the tumour-localizing properties of apoE liposomes and the disposition of an incorporated lipophilic derivative of daunorubicin (LAD). Tissue distribution studies showed that LAD-loaded apoE liposomes were taken up and processed by the major LDL receptor-expressing organs (i.e. adrenals, liver and spleen). Of all other tissues, the tumour showed the highest uptake. The distribution patterns of LAD-loaded apoE liposomes and native LDL in the tumour-bearing mice were very similar, which supports the role of the LDL receptor in the disposition of the prodrug-loaded particles. The disposition of LAD followed the pattern of the liposomal carrier. We conclude that apoE liposomes enable LDL receptor-mediated specific delivery of antineoplastic (pro)drugs to tumours, and, therefore, constitute an attractive novel option for

  8. Crystal Structure of a Human Single Domain Antibody Dimer Formed through VH-VH Non-Covalent Interactions

    PubMed Central

    Li, Shenghua; Tanha, Jamshid; Arbabi-Ghahroudi, Mehdi; Zhang, Jianbing; Wang, Shuying

    2012-01-01

    Single-domain antibodies (sdAbs) derived from human VH are considered to be less soluble and prone to aggregate which makes it difficult to determine the crystal structures. In this study, we isolated and characterized two anti-human epidermal growth factor receptor-2 (HER2) sdAbs, Gr3 and Gr6, from a synthetic human VH phage display library. Size exclusion chromatography and surface plasmon resonance analyses demonstrated that Gr3 is a monomer, but that Gr6 is a strict dimer. To understand this different molecular behavior, we solved the crystal structure of Gr6 to 1.6 Å resolution. The crystal structure revealed that the homodimer assembly of Gr6 closely mimics the VH-VL heterodimer of immunoglobulin variable domains and the dimerization interface is dominated by hydrophobic interactions. PMID:22253912

  9. Antibody-mediated activation of a defective beta-D-galactosidase: dimeric form of the activatable mutant enzyme.

    PubMed

    Conway de Macario, E; Ellis, J; Guzman, R; Rotman, B

    1978-02-01

    Sedimentation analyses of AMEF, an activatable mutant beta-D-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23), and the products of its reaction with Fab fragments of activating antibody show that this enzyme exists mainly as 10S dimers. Activation of AMEF by purified antibody resulted in formation of 16S tetramers. A unifying hypothesis postulating a dimer--tetramer equilibrium accounts for this observation as the counterpart of inactivation, which was shown to involve the breakdown of tetramers into inactive subunits [Roth, R. A. & Rotman, B. (1975) Biochem. Biophys. Res. Commun. 67, 1382--1390]. Conditions are described under which AMEF loses the specific antigenic determinant(s) responsible for binding activating antibody, allowing its subsequent use as an absorption to obtain immunologically purified activating antibody,

  10. Antibody-mediated activation of a defective beta-D-galactosidase: dimeric form of the activatable mutant enzyme.

    PubMed Central

    de Macario, E C; Ellis, J; Guzman, R; Rotman, B

    1978-01-01

    Sedimentation analyses of AMEF, an activatable mutant beta-D-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23), and the products of its reaction with Fab fragments of activating antibody show that this enzyme exists mainly as 10S dimers. Activation of AMEF by purified antibody resulted in formation of 16S tetramers. A unifying hypothesis postulating a dimer--tetramer equilibrium accounts for this observation as the counterpart of inactivation, which was shown to involve the breakdown of tetramers into inactive subunits [Roth, R. A. & Rotman, B. (1975) Biochem. Biophys. Res. Commun. 67, 1382--1390]. Conditions are described under which AMEF loses the specific antigenic determinant(s) responsible for binding activating antibody, allowing its subsequent use as an absorption to obtain immunologically purified activating antibody, PMID:416439

  11. Familial apolipoprotein E deficiency.

    PubMed Central

    Schaefer, E J; Gregg, R E; Ghiselli, G; Forte, T M; Ordovas, J M; Zech, L A; Brewer, H B

    1986-01-01

    A unique kindred with premature cardiovascular disease, tubo-eruptive xanthomas, and type III hyperlipoproteinemia (HLP) associated with familial apolipoprotein (apo) E deficiency was examined. Homozygotes (n = 4) had marked increases in cholesterol-rich very low density lipoproteins (VLDL) and intermediate density lipoproteins (IDL), which could be effectively lowered with diet and medication (niacin, clofibrate). Homozygotes had only trace amounts of plasma apoE, and accumulations of apoB-48 and apoA-IV in VLDL, IDL, and low density lipoproteins. Radioiodinated VLDL apoB and apoE kinetic studies revealed that the homozygous proband had markedly retarded fractional catabolism of VLDL apoB-100, apoB-48 and plasma apoE, as well as an extremely low apoE synthesis rate as compared to normals. Obligate heterozygotes (n = 10) generally had normal plasma lipids and mean plasma apoE concentrations that were 42% of normal. The data indicate that homozygous familial apoE deficiency is a cause of type III HLP, is associated with markedly decreased apoE production, and that apoE is essential for the normal catabolism of triglyceride-rich lipoprotein constituents. Images PMID:3771793

  12. Dimerization interfaces formed between the DNA binding domains determine the cooperative binding of RXR/RAR and RXR/TR heterodimers to DR5 and DR4 elements.

    PubMed Central

    Zechel, C; Shen, X Q; Chambon, P; Gronemeyer, H

    1994-01-01

    We have previously reported that the binding site repertoires of heterodimers formed between retinoid X receptor (RXR) and either retinoic acid receptor (RAR) or thyroid hormone receptor (TR) bound to response elements consisting of directly repeated PuG(G/T)TCA motifs spaced by 1-5 bp [direct repeat (DR) elements 1-5] are highly similar to those of their corresponding DNA binding domains (DBDs). We have now mapped the dimerization surfaces located in the DBDs of RXR, RAR and TR, which are responsible for cooperative interaction on DR4 (RXR and TR) and DR5 (RXR and RAR). The D-box of the C-terminal CII finger of RXR provides one of the surfaces which is specifically required for the formation of the heterodimerization interfaces on both DR4 and DR5. Heterodimerization with the RXR DBD on DR5 specifically requires the tip of the RAR CI finger as the complementary surface, while a 7 amino acid sequence encompassing the 'prefinger region', but not the TR CI finger, is specifically required for efficient dimerization of TR and RXR DBDs on DR4. Importantly, DBD swapping experiments demonstrate not only that the binding site repertoires of the full-length receptors are dictated by those of their DBDs, but also that the formation of distinct dimerization interfaces between the DBDs are the critical determinants for cooperative DNA binding of these receptors to specific DRs. Images PMID:8137825

  13. Electrophoretic analysis of oxidative modification of apolipoprotein E in very low density lipoprotein from fresh human plasma.

    PubMed

    Kashiwagi, S; Nakamura, K; Arai, H; Yamashita, H; Ito, H

    1999-06-01

    Ferrous ion-induced oxidative modification of apoE in lipid peroxidation of human very low density lipoprotein (VLDL) and the role of the cysteinyl group, present in apoE3 but absent in apoE4, were examined. Fresh human VLDL was obtained from healthy volunteers with different apoE phenotypes as determined by isoelectric focusing (IEF). The VLDL was oxidized by incubating with FeSO4. The time course of the lipid peroxidation was determined by thiobarbituric acid (TBA) assay. The sequential oxidative modification of the apoE was demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting with an anti-apoE antibody. To modify the cysteinyl group of apoE3, the VLDL from the apoE3/3 subject was pretreated with cysteamine before the TBA assay and electrophoresis. The ferrous ion-induced peroxidation of the VLDL was pH-dependent, with increased reactivity at acidic pH ranges. In the initial stage of the lipid peroxidation of the VLDL, aggregates were formed involving apoE dimers and apoB via disulfide bonds, followed by the intra- and intermolecular cross-linkings of apoE monomers. The VLDL with apoE3/4 showed a shorter lag time than the VLDL with apoE3/3 in the TBA assay, suggesting a lower antioxidative effect with apoE3/4. The apoE3/3 pretreated with cysteamine showed the patterns of apoE3/4 in IEF and SDS-PAGE with immunoblotting, but it did not show the shortened lag time in the TBA assay. This suggests that factors other than cysteinyl groups contribute to the reduced antioxidative activity of apoE4.

  14. Elevated serum apolipoprotein E is associated with metastasis and poor prognosis of non-small cell lung cancer.

    PubMed

    Luo, Jinmei; Song, Junli; Feng, Pinning; Wang, Yanhong; Long, Weiqing; Liu, Min; Li, Laisheng

    2016-08-01

    Apolipoprotein E (ApoE) is a factor involved in Alzheimer's disease, which recently attracted great attention as an important protein related to tumorigenesis and metastasis. However, serum ApoE levels and its diagnosis and prognosis value in non-small cell lung cancer (NSCLC) patients are still unknown. In 196 NSCLC patients and 203 healthy controls, serum ApoE was measured by turbidimetric immunoassay. The associations of serum ApoE levels with the clinicopathological characteristics and clinical outcomes of NSCLC patients were analyzed. Serum ApoE levels were obviously elevated in NSCLC patients compared with healthy controls (41.6 ± 11.63 vs. 33.8 ± 6.24 mg/L) and were associated with TNM stage, lymph node metastasis status, and distant metastasis status (all P < 0.0001). For NSCLC diagnosis, the area under the receiver operating characteristic (ROC) curve was 0.71 at a specificity of 0.90 and sensitivity of 0.47. For lymph node metastasis predicting, the area under the ROC curve was 0.68 at a specificity of 0.56 and sensitivity of 0.73. From ROC/area under curve (AUC) analysis, we used 41.25 mg/L as the serum ApoE cut-off value, to divide NSCLC patients into two groups, the median survival was 11.0 weeks (95 % CI = 8.7 to 13.3) for patients in high serum ApoE group and 20.0 weeks (95 % CI = 15.0 to 25.0) in low serum ApoE group. Serum ApoE levels elevated in NSCLC patients, which also associated with TNM stages, lymph node metastasis, distant metastasis, and poor prognosis, suggest that serum ApoE may act as a useful clinical serological biomarkers for evaluating the progress of NSCLC.

  15. Apolipoprotein E-knockout mice show increased titers of serum anti-nuclear and anti-dsDNA antibodies

    SciTech Connect

    Wang, Yuehai; Huang, Ziyang; Lu, Huixia; Lin, Huili; Wang, Zhenhua; Chen, Xiaoqing; Ouyang, Qiufang; Tang, Mengxiong; Hao, Panpan; Ni, Jingqin; Xu, Dongming; Zhang, Mingxiang; Zhang, Qunye; Lin, Ling; and others

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer Titers of ANA and anti-dsDNA antibodies were higher in ApoE{sup -/-} than C57B6/L mice. Black-Right-Pointing-Pointer Spleen was greater and splenocyte apoptosis lower in ApoE{sup -/-} than B6 mice. Black-Right-Pointing-Pointer Level of TLR4 was lower in spleen tissue of ApoE{sup -/-} than B6 mice. Black-Right-Pointing-Pointer The TLR4 pathway may participate in maintaining the balance of splenocyte apoptosis. Black-Right-Pointing-Pointer The TLR4 pathway may participate in antibody production in spleen tissue. -- Abstract: Apolipoprotein E-knockout (ApoE{sup -/-}) mice, atherosclerosis-prone mice, show an autoimmune response, but the pathogenesis is not fully understood. We investigated the pathogenesis in female and male ApoE{sup -/-} mice. The spleens of all ApoE{sup -/-} and C57BL/6 (B6) mice were weighed. The serum IgG level and titers of anti-nuclear antibody (ANA) and anti-double-stranded DNA (anti-dsDNA) antibody were assayed by ELISA. Apoptosis of spleen tissue was evaluated by TUNEL. TLR4 level in spleen tissue was tested by immunohistochemistry and Western blot analysis. Levels of MyD88, p38, phosphorylated p38 (pp38), interferon regulatory factor 3 (IRF3) and Bcl-2-associated X protein (Bax) in spleen tissue were detected by Western blot analysis. We also survey the changes of serum autoantibodies, spleen weight, splenocyte apoptosis and the expressions of TLR4, MyD88, pp38, IRF3 and Bax in spleen tissue in male ApoE{sup -/-} mice after 4 weeks of lipopolysaccharide (LPS), Toll-like receptor 4 ligand, administration. ApoE{sup -/-} mice showed splenomegaly and significantly increased serum level of IgG and titers of ANA and anti-dsDNA antibody as compared with B6 mice. Splenocyte apoptosis and the expression of TLR4, MyD88, pp38, IRF3 and Bax in spleen tissue were significantly lower in ApoE{sup -/-} than B6 mice. The expression of TLR4, MyD88, IRF3, pp38, and Bax differed by sex in ApoE{sup -/-} spleen tissue. The

  16. Polychlorinated biphenyl 77 augments angiotensin II-induced atherosclerosis and abdominal aortic aneurysms in male apolipoprotein E deficient mice

    SciTech Connect

    Arsenescu, Violeta; Arsenescu, Razvan; Parulkar, Madhura; Karounos, Michael; Zhang, Xuan; Baker, Nicki; Cassis, Lisa A.

    2011-11-15

    Infusion of angiotensin II (AngII) to hyperlipidemic mice augments atherosclerosis and causes formation of abdominal aortic aneurysms (AAAs). Each of these AngII-induced vascular pathologies exhibit pronounced inflammation. Previous studies demonstrated that coplanar polychlorinated biphenyls (PCBs) promote inflammation in endothelial cells and adipocytes, two cell types implicated in AngII-induced vascular pathologies. The purpose of this study was to test the hypothesis that administration of PCB77 to male apolipoprotein E (ApoE) -/- mice promotes AngII-induced atherosclerosis and AAA formation. Male ApoE-/- mice were administered vehicle or PCB77 (49 mg/kg, i.p.) during week 1 and 4 (2 divided doses/week) of AngII infusion. Body weights and total serum cholesterol concentrations were not influenced by administration of PCB77. Systolic blood pressure was increased in AngII-infused mice administered PCB77 compared to vehicle (156 {+-} 6 vs 137 {+-} 5 mmHg, respectively). The percentage of aortic arch covered by atherosclerotic lesions was increased in AngII-infused mice administered PCB77 compared to vehicle (2.0 {+-} 0.4 vs 0.9 {+-} 0.1%, respectively). Lumen diameters of abdominal aortas determined by in vivo ultrasound and external diameters of excised suprarenal aortas were increased in AngII-infused mice administered PCB77 compared to vehicle. In addition, AAA incidence increased from 47 to 85% in AngII-infused mice administered PCB77. Adipose tissue in close proximity to AAAs from mice administered PCB77 exhibited increased mRNA abundance of proinflammatory cytokines and elevated expression of components of the renin-angiotensin system (angiotensinogen, angiotensin type 1a receptor (AT1aR)). These results demonstrate that PCB77 augments AngII-induced atherosclerosis and AAA formation. -- Highlights: Black-Right-Pointing-Pointer Polychlorinated biphenyl 77 (PCB77) promotes AngII-induced hypertension. Black-Right-Pointing-Pointer PCB77 augments Ang

  17. Haptoglobin increases with age in rat hippocampus and modulates Apolipoprotein E mediated cholesterol trafficking in neuroblastoma cell lines

    PubMed Central

    Spagnuolo, Maria Stefania; Maresca, Bernardetta; Mollica, Maria Pina; Cavaliere, Gina; Cefaliello, Carolina; Trinchese, Giovanna; Esposito, Maria Grazia; Scudiero, Rosaria; Crispino, Marianna; Abrescia, Paolo; Cigliano, Luisa

    2014-01-01

    Alteration in cholesterol metabolism has been implicated in the pathogenesis of several neurodegenerative disorders. Apolipoprotein E (ApoE) is the major component of brain lipoproteins supporting cholesterol transport. We previously reported that the acute-phase protein Haptoglobin (Hpt) binds ApoE, and influences its function in blood cholesterol homeostasis. Major aim of this study was to investigate whether Hpt influences the mechanisms by which cholesterol is shuttled from astrocytes to neurons. In detail it was studied Hpt effect on ApoE-dependent cholesterol efflux from astrocytes and ApoE-mediated cholesterol incorporation in neurons. We report here that Hpt impairs ApoE-mediated cholesterol uptake in human neuroblastoma cell line SH-SY5Y, and limits the toxicity of a massive concentration of cholesterol for these cells, while it does not affect cholesterol efflux from the human glioblastoma-astrocytoma cell line U-87 MG. As aging is the most important non-genetic risk factor for various neurodegenerative disorders, and our results suggest that Hpt modulates ApoE functions, we evaluated the Hpt and ApoE expression profiles in cerebral cortex and hippocampus of adolescent (2 months), adult (5 and 8 months), and middle-aged (16 months) rats. Hpt mRNA level was higher in hippocampus of 8 and 16 month-old than in 2-month old rats (p < 0.05), and Hpt concentration increased with the age from adolescence to middle-age (p < 0.001). ApoE concentration, in hippocampus, was higher (p < 0.001) in 5 month-old rats compared to 2 month but did not further change with aging. No age-related changes of Hpt (protein and mRNA) were found in the cortex. Our results suggest that aging is associated with changes, particularly in the hippocampus, in the Hpt/ApoE ratio. Age-related changes in the concentration of Hpt were also found in human cerebrospinal fluids. The age-related changes might affect neuronal function and survival in brain, and have important implications in brain

  18. Association between features of the insulin resistance syndrome and Alzheimer's disease independently of apolipoprotein E4 phenotype: cross sectional population based study.

    PubMed Central

    Kuusisto, J.; Koivisto, K.; Mykkänen, L.; Helkala, E. L.; Vanhanen, M.; Hänninen, T.; Kervinen, K.; Kesäniemi, Y. A.; Riekkinen, P. J.; Laakso, M.

    1997-01-01

    OBJECTIVE: To determine the association between features of the insulin resistance syndrome and Alzheimer's disease. DESIGN: Cross sectional population based study. SUBJECTS: 980 people aged 69 to 78 (349 men, 631 women). SETTING: Population of Kuopio, eastern Finland. MAIN OUTCOME MEASURES: Presence of features of the insulin resistance syndrome and diagnosis of Alzheimer's disease by detailed neurological and neuropsychological evaluation. RESULTS: 46 (4.7%) subjects were classified as having probable or possible Alzheimer's disease. In univariate analyses, apolipoprotein E4 phenotype (odds ratio; 95% confidence interval 3.24: 1.77 to 5.92), age (1.16; 1.05 to 1.29), low level of education (0.82; 0.72 to 0.93), low total cholesterol concentration (0.77; 0.59 to 1.00), high systolic blood pressure (1.01; 1.00 to 1.03), high fasting and 2 hour plasma glucose concentrations (1.11; 1.01 to 1.23 and 1.08; 1.03 to 1.13, respectively), high fasting and 2 hour insulin concentrations (1.05; 1.02 to 1.08 and 1.003; 1.00 to 1.01, respectively), and abnormal glucose tolerance (1.86; 1.23 to 2.80) were significantly associated with Alzheimer's disease. In multivariate analysis including apolipoprotein E4 phenotype, age, education, systolic blood pressure, total cholesterol concentration, fasting glucose concentration, and insulin concentration, apolipoprotein E4 phenotype, age, education, total cholesterol, and insulin were significantly associated with Alzheimer's disease. In 532 non-diabetic subjects without the e4 allele hyperinsulinaemia was associated with an increased risk for Alzheimer's disease (prevalence of disease 7.5% v 1.4% in normoinsulinaemic subjects, P = 0.0004). In contrast, in the 228 with the e4 allele hyperinsulinaemia had no effect on the risk of disease (7.0% v 7.1%, respectively). CONCLUSION: Features of the insulin resistance syndrome are associated with Alzheimer's disease independently of apolipoprotein E4 phenotype. PMID:9366728

  19. Cannabidiol-2',6'-dimethyl ether stimulates body weight gain in apolipoprotein E-deficient BALB/c. KOR/Stm Slc-Apoe(shl) mice.

    PubMed

    Takeda, Shuso; Hirota, Rena; Teradaira, Sari; Takeda-Imoto, Masumi; Watanabe, Kazuhito; Toda, Akihisa; Aramaki, Hironori

    2015-12-01

    The biological activities of cannabidiol (CBD), a major non-psychotropic constituent of the fiber-type cannabis plant, have been examined in detail (e.g., CBD modulation of body weight in mice and rats). However, few studies have investigated the biological activities of cannabidiol-2',6'-dimethyl ether (CBDD), a dimethyl ether derivative of the parent CBD. We herein focused on the effects of CBDD on body weight changes in mice, and demonstrated that it stimulated body weight gain in apolipoprotein E (ApoE)-deficient BALB/c. KOR/Stm Slc-Apoe(shl) mice, especially between 10 and 20 weeks of age.

  20. A novel 1:1 canal inclusion network formed by deoxycholic acid dimers (bislactones) with benzene molecules: an x-ray study

    NASA Astrophysics Data System (ADS)

    Stanković, S.; Kálmán, A.; Argay, Gy.; Miljković, D.; Kuhajda, K.; Vicković, I.; Bruwo, M.; Ori, O.

    1990-04-01

    A novel canal inclusion network formed by 3α-hydroxy-5β-cholano-12α-24-bislactone (C 48H 74O 6) with benzene molecule (1:1) in a triclinic crystal lattice has been revealed by X-ray diffraction and 1H NMR spectroscopy. Crystal symmetry P1 with a=15.036(4), b=13.269(4), c=7.196(4) Å, α=78.16(2), β=73.42(2), γ=66.42(2) °, Z=1 (one pair of deoxycholic acid (DCA) dimer and benzene in the unit cell) and Dc=1.091 g cm -3. The structure was refined to R 0.082 for 3083 reflections. The DCA dimers separated by unit translations form infinite canals along the shortest axis c. These hydrophobic canals accommodate the benzene molecules separated by a distance of 4.55(2) Å. In accordance with the vigorous thermal motion of the ring atoms the benzene molecules are bound by weak dispersion forces to the host molecules. However, atom—atom potential calculations indicate that the position and orientation of the benzene ring in the void represent the energy minimum.

  1. Rice α-globulin decreases serum cholesterol concentrations in rats fed a hypercholesterolemic diet and ameliorates atherosclerotic lesions in apolipoprotein E-deficient mice.

    PubMed

    Tong, Li-Tao; Fujimoto, Yumiko; Shimizu, Naoki; Tsukino, Mariko; Akasaka, Taiki; Kato, Yukiko; Iwamoto, Wakako; Shiratake, Sawako; Imaizumi, Katsumi; Sato, Masao

    2012-05-01

    The hypocholesterolemic and antiatherogenic effects of rice α-globulin remain unclear. We investigated the hypocholesterolemic effect of rice α-globulin in rats fed a hypercholesterolemic diet. The rats were divided into 4 groups and were orally administrated the following three proteins or a vehicle for 4weeks: rice protein, rice α-globulin, or soy β-conglycinin at a dose of 100mg/kg body weight or carboxymethylcellulose to the control rats. In the rice α-globulin group, serum cholesterol concentrations were 28% lower than the control group and fecal neutral steroid excretion was increased by 30%. The hypocholesterolemic effect of rice α-globulin was equal to soy β-conglycinin in SD rats fed the hypercholesterolemic diet. However, the serum cholesterol concentrations in the rice protein group did not change compared to the control group. To investigate the antiatherogenic effects of rice α-globulin, male apolipoprotein E-deficient mice were orally administered the same dose of rice α-globulin for 9weeks. The en face lesion area in the aorta was 46% lower than in the control group. In conclusion, administration of rice α-globulin improves hypercholesterolemia in rats fed a hypercholesterolemic diet by increasing the fecal excretion of neutral sterols, and inhibits atherosclerosis development in apolipoprotein E-deficient mice. The anti-atherosclerotic effect exerts by mechanism(s) other than the regulation of serum MCP-1 and NO concentrations.

  2. Identification of a Nuclear Respiratory Factor 1 Recognition Motif in the Apolipoprotein E Variant APOE4 linked to Alzheimer’s Disease

    PubMed Central

    Urfer-Buchwalder, Anne; Urfer, Roman

    2017-01-01

    Alzheimer’s disease affects tens of millions of people worldwide and its prevalence continues to rise. It is caused by a combination of a subject’s heredity, environment, lifestyle, and medical condition. The most significant genetic risk factor for late onset Alzheimer’s disease is a variant of the apolipoprotein E gene, APOE4. Here we show that the single nucleotide polymorphism rs429358 that defines APOE4 is located in a short sequence motif repeated several times within exon 4 of apolipoprotein E, reminiscent of the structure of transcriptional enhancers. A JASPAR database search predicts that the T to C transition in rs429358 generates a binding motif for nuclear respiratory factor NRF1. This site appears to be part of a binding site cluster for this transcription factor on exon 4 of APOE. This de novo NRF1 binding site has therefore the potential to affect the expression of multiple genes in its genomic vicinity. Our in silico analysis, suggesting a novel function for APOE4 at the DNA level, offers a potential mechanism for the observed tissue specific neurodegeneration and the role of environmental factors in Alzheimer’s disease etiology. PMID:28094792

  3. Lack of Toll-like receptor 4 or myeloid differentiation factor 88 reduces atherosclerosis and alters plaque phenotype in mice deficient in apolipoprotein E.

    PubMed

    Michelsen, Kathrin S; Wong, Michelle H; Shah, Prediman K; Zhang, Wenxuan; Yano, Juliana; Doherty, Terence M; Akira, Shizuo; Rajavashisth, Tripathi B; Arditi, Moshe

    2004-07-20

    Toll-like receptors (TLRs) and the downstream adaptor molecule myeloid differentiation factor 88 (MyD88) play an essential role in the innate immune responses. Here, we demonstrate that genetic deficiency of TLR4 or MyD88 is associated with a significant reduction of aortic plaque areas in atherosclerosis-prone apolipoprotein E-deficient mice, despite persistent hypercholesterolemia, implying an important role for the innate immune system in atherogenesis. Apolipoprotein E-deficient mice that also lacked TLR4 or MyD88 demonstrated reduced aortic atherosclerosis that was associated with reductions in circulating levels of proinflammatory cytokines IL-12 or monocyte chemoattractant protein 1, plaque lipid content, numbers of macrophage, and cyclooxygenase 2 immunoreactivity in their plaques. Endothelial-leukocyte adhesion in response to minimally modified low-density lipoprotein was reduced in aortic endothelial cells derived from MyD88-deficient mice. Taken together, our results suggest an important role for TLR4 and MyD88 signaling in atherosclerosis in a hypercholesterolemic mouse model, providing a pathophysiologic link between innate immunity, inflammation, and atherogenesis.

  4. Crystalline products isolated from solutions with commercially available 2,3-bis(2-pyridyl)pyrazine (dpp) as reactant: Detection of a dimerized form of dpp

    NASA Astrophysics Data System (ADS)

    Grove, Hilde; Frøystein, Nils Åge; Sæthre, Leif J.; Sletten, Jorunn

    2006-12-01

    From reaction mixtures of commercially available 2,3-bis(2-pyridyl)pyrazine (dpp) and perchloric acid four different solid products have been isolated and structurally characterized by X-ray crystallography; (dppH 2)(ClO 4) 2·3H 2O ( 1), (dppH 2)(ClO 4) 2 ( 2), (ddppH 2)(ClO 4) 2 ( 3) and (dppH)(ClO 4) ( 4) (dppH is monoprotonated dpp, dppH 2 is the diprotonated dication of dpp, ddppH 2 is the dication 5,5'-bis(2,3-bis(2-pyridyl)pyrazinium), i.e. dimerized dppH). In 1 and 2 the nitrogen atom in both of the pyridyl rings in dpp is protonated. Hydrogen bonding and packing arrangements differ in the two compounds. In 3 a protonated and dimerized form of dpp is found; two 2,3-bis(2-pyridyl)pyrazinium units are connected by a C(sp 2) sbnd C(sp 2) bond in the 5-positions of the pyrazine rings, one pyridyl ring in each dpp moiety being protonated at the nitrogen. Strong intra-cation N sbnd H⋯N bonds between pyridyl rings are present. In 4 the monomeric dppH moieties display the same type of intramolecular hydrogen bonds as found in 3. Upon reacting dpp with copper(II) salts and oxalate, a dinuclear copper (II) complex, [Cu 2(ddpp)(ox) 2(H 2O) 2] (ddpp = 5,5'-bis(2,3-bis(2-pyridyl)pyrazine)), as well as mononuclear [Cu(dpp)(ox)(H 2O)] have been obtained in the same reaction mixtures. In one of the isolated crystalline products a dimer of dpp is found, as described in the case of compound 3, but no protonation has occurred. The crystal structure determination reveals a dinuclear complex with the neutral ddpp (dimerized dpp) as bridging ligand. Oxalate occurs as a bidentate, terminal ligand; water completes the copper coordination sphere. The dinuclear complex cocrystallizes with a mononuclear Cu-dpp-ox complex; in the mixed crystal two mononuclear units replace one dinuclear unit in 25% of the unit cells, thus the average formula is [Cu 2(ddpp)(ox) 2(H 2O) 2] 0.75[{Cu(dpp)(ox)(H 2O)} 2] 0.25·8H 2O ( 5). The monomeric species also crystallizes in the form of compound

  5. Effect of rubidium and cesium ions on the dimeric quaduplex formed by the Oxytricha nova telomeric repeat oligonucleotide d(GGGGTTTTGGGG).

    PubMed

    Marincola, Flaminia Cesare; Virno, Ada; Randazzo, Antonio; Lai, Adolfo

    2007-01-01

    The DNA sequence d(GGGGTTTTGGGG) consists of 1.5 units of the repeat in telomeres of Oxytricha nova. It has been shown by NMR and x-ray crystallographic analysis that it is capable to form a dimeric quadruplex structure and that a variety of cations, namely K(+), Na(+), and NH(4)(+), are able to interact with this complex with different affinity, leading to complexes characterized by different local conformations. Thus, in order to improve the knowledge of this kind of molecule, and in particular to provide further insight into the role of monovalent cations in the G-quadruplex folding and conformation, we have investigated by (1)H-NMR the effect of the addition of Rb(+) and Cs(+) to the quadruplex formed by the oligonucleotide d(GGGGTTTTGGGG).

  6. The number of cysteine residues per mole in apolipoprotein E affects systematically synchronous neural interactions in women's healthy brains.

    PubMed

    Leuthold, Arthur C; Mahan, Margaret Y; Stanwyck, John J; Georgopoulos, Angeliki; Georgopoulos, Apostolos P

    2013-05-01

    Apolipoprotein E (apoE) is involved in lipid metabolism in the brain, but its effects on brain function are not understood. Three apoE isoforms (E4, E3, and E2) are the result of cysteine-arginine interchanges at two sites: there are zero interchanges in E4, one interchange in E3, and two interchanges in E2. The resulting six apoE genotypes (E4/4, E4/3, E4/2, E3/3, E3/2, E2/2) yield five groups with respect to the number of cysteine residues per mole (CysR/mole), as follows. ApoE4/4 has zero cysteine residues per mole (0-CysR/mole), E4/3 has one (1-CysR/mole), E4/2 and E3/3 each has two (2-CysR/mole), E3/2 has three (3-CysR/mole), and E2/2 has four (4-CysR/mole). The use of the number of CysR/mole to characterize the apoE molecule converts the categorical apoE genotype scale, consisting of 6 distinct genotypes above, to a 5-point continuous scale (0-4 CysR/mole). This allows the use of statistical analyses suitable for continuous variables (e.g. regression) to quantify the relations between various variables and apoE. Using such analyses, here, we show for the first time that apoE affects in a graded and orderly manner neural communication, as assessed by analyzing the relation between the number of CysR/mole and synchronous neural interactions (SNI) measured by magnetoencephalography (MEG) in 130 cognitively healthy women. At the one end of the CysR/mole range, the 4-CysR/mole (E2/2) SNI distribution had the highest mean, lowest variance, lowest range, and lowest coefficient of variation, whereas at the other end, 0-CysR/mole (E4/4) SNI distribution had the lowest mean, highest variance, highest range, and highest coefficient of variation. The special status of the 4-CysR/mole distribution was reinforced by the results of a hierarchical tree analysis where the 4-CysR/mole (E2/2) SNI distribution occupied a separate branch by itself and the remaining CysR/mole SNI distributions were placed at increasing distances from the 4-CysR/mole distribution, according to

  7. Exploring the effects of the atherosclerosis progression and the choice of affected arteries in the design of experiments with Apolipoprotein E-deficient mice.

    PubMed

    Riera-Borrull, Marta; Sabench, Fàtima; del Castillo, Daniel; Camps, Jordi; Joven, Jorge

    2016-01-01

    The objective of this study is to explore the longitudinal progression of atherosclerosis and the correlation between methods to measure the lesion in apolipoprotein E-deficient mice. Atherosclerosis progression was assessed by measurements of foam cell-rich depositions in their proximal aortas, and/or in surgically excised arteries, to assess the histological luminal narrowing. A longitudinal study was performed by comparing the values for carotid, aorta, and femoral and iliac arteries using common histological techniques. There were no significant differences in progression between different arteries, but correlation with the classical measurement of atherosclerosis in the aortic root was poor. Each laboratory requires specific standardization. Carotid arteries were sensitive to atherosclerosis in these mice, and progression was exponential. In conclusion, morphometric data show the importance of the choice of the duration of treatment, the appropriate controls, and the age at which to begin the experiments.

  8. UNC-45/CRO1/She4p (UCS) Protein Forms Elongated Dimer and Joins Two Myosin Heads Near Their Actin Binding Region

    SciTech Connect

    H Shi; G Blobel

    2011-12-31

    UNC-45/CRO1/She4p (UCS) proteins have variously been proposed to affect the folding, stability, and ATPase activity of myosins. They are the only proteins known to interact directly with the motor domain. To gain more insight into UCS function, we determined the atomic structure of the yeast UCS protein, She4p, at 2.9 {angstrom} resolution. We found that 16 helical repeats are organized into an L-shaped superhelix with an amphipathic N-terminal helix dangling off the short arm of the L-shaped molecule. In the crystal, She4p forms a 193-{angstrom}-long, zigzag-shaped dimer through three distinct and evolutionary conserved interfaces. We have identified She4p's C-terminal region as a ligand for a 27-residue-long epitope on the myosin motor domain. Remarkably, this region consists of two adjacent, but distinct, binding epitopes localized at the nucleotide-responsive cleft between the nucleotide- and actin-filament-binding sites. One epitope is situated inside the cleft, the other outside the cleft. After ATP hydrolysis and Pi ejection, the cleft narrows at its base from 20 to 12 {angstrom} thereby occluding the inside the cleft epitope, while leaving the adjacent, outside the cleft binding epitope accessible to UCS binding. Hence, one cycle of higher and lower binding affinity would accompany one ATP hydrolysis cycle and a single step in the walk on an actin filament rope. We propose that a UCS dimer links two myosins at their motor domains and thereby functions as one of the determinants for step size of myosin on actin filaments.

  9. Helix geometry of single stranded DNA 'A' and 'B' forms from minimum energy conformations of dimeric subunits.

    PubMed Central

    Hingerty, B; Broyde, S

    1978-01-01

    Low energy conformations with dihedral angles similar to those occurring in fibers of the 'A' and 'B' forms of DNAs have been calculated for the deoxydinucleoside phosphates dApdA, dCpdC, dTpdT, dGpdG and dGpdC (1-3). These conformers have been used as building blocks for generating larger single stranded polymers, whose helical parameters we have calculated. We find that single stranded 'A' and 'B' form helices tend to be narrower and more tightly wound than the duplexes obtained in fibers (4,5). This is consistent with experimental observations on single stranded fibers of poly (rC) (6). We also find that the different sequences have different helix geometries. In addition, it is observed that large variations in helix geometry for a given sequence are achievable at little energetic cost. PMID:643603

  10. Human macrophages produce dimeric forms of IL-18 which can be detected with monoclonal antibodies specific for inactive IL-18.

    PubMed

    Kikkawa, S; Matsumoto, M; Shida, K; Fukumori, Y; Toyoshima, K; Seya, T

    2001-02-23

    We established two monoclonal antibodies (mAbs) which specifically recognize human 'functionally inactive' recombinant IL-18, and IL-18 protein polymorphism was examined using human monocytes and macrophages (M phi). In 6 day GM-CSF-treated M phi, an 'inactive' IL-18-recognizing mAb 21 detected the IL-18 proform (24 kDa) and a 48-kDa protein, which were gradually increased concomitant with maturation stage. Majority of the 24- and 48-kDa forms were barely detectable with other mAbs recognizing 'active' IL-18. No reagents including Toll stimulators up-regulated these IL-18 populations in M phi. The 21-recognizable IL-18 species were separated using an anion-exchanger column and their IFN gamma-inducing activity was assessed with human lymphocytes plus IL-12. Virtually no as yet known activity was detected with these IL-18 species. After processed with M phi proteases, an 18-kDa form was generated to express the IFN gamma-inducing activity, although the activity was far weaker than that of control 'active' IL-18. These observations suggested that large amounts of various IL-18 species are produced with monocyte-M phi differentiation and most of these IL-18 species are functionally 'inactive' in terms of the reported IL-18 function even after proteolytic 18-kDa conversion.

  11. Crystal Structure of a Novel Dimeric Form of NS5A Domain I Protein from Hepatitis C Virus

    SciTech Connect

    Love, Robert A.; Brodsky, Oleg; Hickey, Michael J.; Wells, Peter A.; Cronin, Ciarán N.; Pfizer

    2009-07-10

    A new protein expression vector design utilizing an N-terminal six-histidine tag and tobacco etch virus protease cleavage site upstream of the hepatitis C virus NS5A sequence has resulted in a more straightforward purification method and improved yields of purified NS5A domain I protein. High-resolution diffracting crystals of NS5A domain I (amino acids 33 to 202) [NS5A(33-202)] were obtained by using detergent additive crystallization screens, leading to the structure of a homodimer which is organized differently from that published previously (T. L. Tellinghuisen, J. Marcotrigiano, and C. M. Rice, Nature 435:374-379, 2005) yet is consistent with a membrane association model for NS5A. The monomer-monomer interface of NS5A(33-202) features an extensive buried surface area involving the most-highly conserved face of each monomer. The two alternate structural forms of domain I now available may be indicative of the multiple roles emerging for NS5A in viral RNA replication and viral particle assembly.

  12. Cloning of a cDNA encoding a putative human very low density lipoprotein/Apolipoprotein E receptor and assignment of the gene to chromosome 9pter-p23[sup 6

    SciTech Connect

    Gafvels, M.E.; Strauss, J.F. III ); Caird, M.; Patterson, D. ); Britt, D.; Jackson, C.L. )

    1993-11-01

    The authors report the cloning of a 3656-bp cDNA encoding a putative human very low density lipoprotein (VLDL)/apolipoprotein E (ApoE) receptor. The gene encoding this protein was mapped to chromosome 9pter-p23. Northern analysis of human RNA identified cognate mRNAs of 6.0 and 3.8 kb with most abundant expression in heart and skeletal muscle, followed by kidney, placenta, pancreas, and brain. The pattern of expression generally paralleled that of lipoprotein lipase mRNA but differed from that of the low density lipoprotein (LDL) receptor and the low density lipoprotein receptor-related protein/[alpha][sub 2]-macroglobulin receptor (LRP), which are members of the same gene family. VLDL/ApoE receptor message was not detected in liver, whereas mRNAs for both LDL receptor and LRP were found in hepatic tissue. In mouse 3T3-L1 cells, VLDL/ApoE receptor mRNA was induced during the transformation of the cells into adipocytes. Expression was also detected in human choriocarcinoma cells, suggesting that at least part of the expression observed in placenta may be in trophoblasts, cells which would be exposed to maternal blood. Expression in brain may be related to high levels of ApoE expression in that organ, an observation of potential relevance to the recently hypothesized role for ApoE in late onset Alzheimer disease. The results suggest that the putative VLDL/ApoE receptor could play a role in the uptake of triglyceride-rich lipoprotein particles by specific organs including striated and cardiac muscle and adipose tissue and in the transport of maternal lipids across the placenta. The findings presented here, together with recent observations from other laboratories, bring up the possibility that a single gene, the VLDL/ApoE receptor, may play a role in the pathogenesis of certain forms of atherosclerosis, Alzheimer disease, and obesity.

  13. Hyperglycemia Induced by Glucokinase Deficiency Accelerates Atherosclerosis Development and Impairs Lesion Regression in Combined Heterozygous Glucokinase and the Apolipoprotein E-Knockout Mice

    PubMed Central

    Adingupu, Damilola D.; Andréasson, Anne-Christine; Ahnmark, Andrea

    2016-01-01

    Aim. Models combining diabetes and atherosclerosis are important in evaluating the cardiovascular (CV) effects and safety of antidiabetes drugs in the development of treatments targeting CV complications. Our aim was to evaluate if crossing the heterozygous glucokinase knockout mouse (GK+/−) and hyperlipidemic mouse deficient in apolipoprotein E (ApoE−/−) will generate a disease model exhibiting a diabetic and macrovascular phenotype. Methods. The effects of defective glucokinase on the glucose metabolism and on the progression and regression of atherosclerosis on high-fat diets were studied in both genders of GK+/−ApoE−/− and ApoE−/− mice. Coronary vascular function of the female GK+/−ApoE−/− and ApoE−/− mice was also investigated. Results. GK+/−ApoE−/− mice show a stable hyperglycemia which was increased on Western diet. In oral glucose tolerance test, GK+/−ApoE−/− mice showed significant glucose intolerance and impaired glucose-stimulated insulin secretion. Plasma lipids were comparable with ApoE−/− mice; nevertheless the GK+/−ApoE−/− mice showed slightly increased atherosclerosis development. Conclusions. The GK+/−ApoE−/− mice showed a stable and reproducible hyperglycemia, accelerated atherosclerotic lesion progression, and no lesion regression after lipid lowering. This novel model provides a promising tool for drug discovery, enabling the evaluation of compound effects against both diabetic and cardiovascular endpoints simultaneously in one animal model. PMID:27774459

  14. Sesamin attenuates intercellular cell adhesion molecule-1 expression in vitro in TNF-alpha-treated human aortic endothelial cells and in vivo in apolipoprotein-E-deficient mice.

    PubMed

    Wu, Wen-Huey; Wang, Shu-Huei; Kuan, I-I; Kao, Ya-Shi; Wu, Pei-Jhen; Liang, Chan-Jung; Chien, Hsiung-Fei; Kao, Chiu-Hua; Huang, Ching-Jang; Chen, Yuh-Lien

    2010-09-01

    Sesame lignans have antioxidative and anti-inflammatory properties. We focused on the effects of the lignans sesamin and sesamol on the expression of endothelial-leukocyte adhesion molecules in tumor necrosis factor-alpha (TNF-alpha)-treated human aortic endothelial cells (HAECs). When HAECs were pretreated with sesamin (10 or 100 microM), the TNF-alpha-induced expression of intercellular cell adhesion molecule-1 (ICAM-1) was significantly reduced (35 or 70% decrease, respectively) by Western blotting. Sesamol was less effective at inhibiting ICAM-1 expression (30% decrease at 100 microM). Sesamin and sesamol reduced the marked TNF-alpha-induced increase in human antigen R (HuR) translocation and the interaction between HuR and the 3'UTR of ICAM-1 mRNA. Both significantly reduced the binding of monocytes to TNF-alpha-stimulated HAECs. Sesamin significantly attenuated TNF-alpha-induced ICAM-1 expression and cell adhesion by downregulation of extracellular signal-regulated kinase 1/2 and p38. Furthermore, in vivo, sesamin attenuated intimal thickening and ICAM-1 expression seen in aortas of apolipoprotein-E-deficient mice. Taken together, these data suggest that sesamin inhibits TNF-alpha-induced extracellular signal-regulated kinase/p38 phosphorylation, nuclear translocation of NF-kappaB p65, cytoplasmic translocalization of HuR and thereby suppresses ICAM-1 expression, resulting in reduced adhesion of leukocytes. These results also suggest that sesamin may prevent the development of atherosclerosis and inflammatory responses.

  15. Noninvasive in vivo magnetic resonance imaging of injury-induced neointima formation in the carotid artery of the apolipoprotein-E null mouse.

    PubMed

    Manka, D R; Gilson, W; Sarembock, I; Ley, K; Berr, S S

    2000-11-01

    Mice deficient in apolipoprotein-E (apoE) experience severe hypercholesterolemia, are prone to atherosclerosis, and recently have emerged as a powerful tool in the study of plaque formation. In this study, we developed magnetic resonance (MR) imaging methods to detect the progression of atherosclerosis noninvasively in a mouse model of arterial injury. Four 14-week-old apoE-deficient mice were imaged 5 weeks after beginning an atherogenic Western diet and 4 weeks after wire denudation injury of the left common carotid artery (LCCA). Information from several images was combined into high-information content images using methods previously developed. The image resolution was 47 x 47 x 750 microm(3). We acquired T1-, T2-, and proton density (PD)-weighted images (TR/TE 650/14, 2000/60, and 2000/14 msec, respectively). Each 8-bit image was placed in a separate color channel to produce a 24-bit color image (red = T1, green = PD, and blue = T2). The composite image created contrast between different tissue types that was superior to that of any single image and revealed significant luminal narrowing of the LCCA, but not the uninjured RCCA. MR images were compared with corresponding histopathology cross sections and luminal area measurements from each method correlated(r2= 0.61). Atherosclerotic luminal narrowing was successfully detected through MR imaging in a mouse model of arterial injury that is small, reproduces quickly, and lends itself to genetic analysis and manipulation.

  16. Abnormalities in apolipoprotein and lipid levels in an HIV-infected Brazilian population under different treatment profiles: the relevance of apolipoprotein E genotypes and immunological status.

    PubMed

    Malavazi, Iran; Abrão, Emiliana P; Mikawa, Angela Y; Landgraf, Viviane O; da Costa, Paulo I

    2004-05-01

    HIV infection is associated with disturbances in lipid metabolism due to a host's response mechanism and the current antiretroviral therapy. The pathological appearance and progression of atherosclerosis is dependent on the presence of injurious agents in the vascular endothelium and variations in different subsets of candidate genes. Therefore, the Hha I polymorphism in the apolipoprotein E gene was evaluated in addition to triglycerides, total cholesterol, very low-density lipoprotein (VLDL), LDL, high-density lipoprotein (HDL), and apolipoprotein (apo) Al, B and E levels in 86 Brazilian HIV-infected patients and 29 healthy controls. The allele frequency for apoE in the HIV-infected group and controls was in agreement with data on the Brazilian population. Dyslipidemia was observed in the HIV group and verified by increased levels of triglycerides, VLDL and apoE, and decreased levels of HDL and apoAl. The greatest abnormalities in these biochemical variables were shown in the HIV-infected individuals whose immune function was more compromised. The effect of the genetic variation at the APOE gene on biochemical variables was more pronounced in the HIV-infected individuals who carried the apoE2/3 genotype. The highly active anti-retroviral therapy (HAART)-receiving group presented increased levels of total cholesterol and apoE. Dyslipidemia was a predictable consequence of HIV infection and the protease inhibitors intensified the increase in apoE values.

  17. Restraint stress up-regulates lectin-like oxidized low-density lipoprotein receptor-1 in aorta of apolipoprotein E-deficient mice.

    PubMed

    Andersson, Irene J; Sankaralingam, Sowndramalingam; Davidge, Sandra T

    2010-09-01

    Psychological stress is a risk factor for cardiovascular disease including atherosclerosis, but the mechanisms are unknown. The vascular lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is involved in vascular pathology and early atherogenesis. We hypothesized that LOX-1 is up-regulated by psychological stress via the formation of oxygen-derived free radicals, and that treatment with EUK-8 (a superoxide dismutase and catalase mimetic) prevents production of oxygen-derived free radicals and leads to reduced expression of LOX-1 in the vascular wall. As a model for psychological stress, we exposed male apolipoprotein E-deficient mice to repeated restraint stress by placement in a conical tube for 2 h per day for 14 consecutive days. Stressed and control mice were treated with EUK-8 (n = 4-5) or vehicle (n = 4-5). Reactive oxygen species and peroxynitrite levels, as detected by oxidative fluorescence microscopy, were increased in the aortic root of mice exposed to stress compared to those of controls by 212 +/- 22% (mean +/- SEM; p < 0.001) and 110 +/- 6% (p < 0.001), respectively. LOX-1, as detected by immunohistochemistry, was increased by 443 +/- 63% in stressed mice compared to control mice (p < 0.001). EUK-8 reduced reactive oxygen species, peroxynitrite, and LOX-1 levels in stressed mice compared to vehicle-treated stressed mice. To conclude, LOX-1 induced by reactive oxygen species and/or peroxynitrite could be one mechanism by which stress promotes cardiovascular disease.

  18. Influence of brain-derived neurotrophic factor and apolipoprotein E genetic variants on hemispheric and lateral ventricular volume of young healthy adults

    PubMed Central

    Sidiropoulos, Christos; Jafari-Khouzani, Kourosh; Soltanian-Zadeh, Hamid; Mitsias, Panayiotis; Alexopoulos, Panagiotis; Richter-Schmidinger, Tanja; Reichel, Martin; Lewczuk, Piotr; Doerfler, Arnd; Kornhuber, Johannes

    2011-01-01

    Objective Brain-derived neurotrophic factor (BDNF) and apolipoprotein E (ApoE) are thought to be implicated in a variety of neuronal processes, including cell growth, resilience to noxious stimuli and synaptic plasticity. A Val to Met substitution at codon 66 in the BDNF protein has been associated with a variety of neuropsychiatric conditions. The ApoE4 allele is considered a risk factor for late-onset Alzheimer’s disease, but its effects on young adults are less clear. We sought to investigate the effects of those two polymorphisms on hemispheric and lateral ventricular volumes of young healthy adults. Methods Hemispheric and lateral ventricular volumes of 144 healthy individuals, aged 19–35 years, were measured using high resolution magnetic resonance imaging and data were correlated with BDNF and ApoE genotypes. Results There were no correlations between BDNF or ApoE genotype and hemispheric or lateral ventricular volumes. Conclusion These findings indicate that it is unlikely that either the BDNF Val66Met or ApoE polymorphisms exert any significant effect on hemispheric or lateral ventricular volume. However, confounding epistatic genetic effects as well as relative insensitivity of the volumetric methods used cannot be ruled out. Further imaging analyses are warranted to better define any genetic influence of the BDNF Val6Met and ApoE polymorphism on brain structure of young healthy adults. PMID:21701702

  19. Blocking the Apolipoprotein E/Amyloid β Interaction in Triple Transgenic Mice Ameliorates Alzheimer’s Disease Related Amyloid β and Tau Pathology

    PubMed Central

    Liu, Shan; Breitbart, Ariel; Sun, Yanjie; Mehta, Pankaj D.; Boutajangout, Allal; Scholtzova, Henrieta; Wisniewski, Thomas

    2013-01-01

    Inheritance of the apolipoprotein E4 (apoE4) genotype has been identified as the major genetic risk factor for late-onset Alzheimer’s disease (AD). Studies have shown that the binding between apoE and amyloid-β (Aβ) peptides occurs at residues 244–272 of apoE and residues 12–28 of Aβ. ApoE4 has been implicated in promoting Aβ deposition and impairing clearance of Aβ. We hypothesized that blocking the apoE/Aβ interaction would serve as an effective new approach to AD therapy. We have previously shown that treatment with Aβ12–28P can reduce amyloid plaques in APP/PS1 transgenic (Tg) mice and vascular amyloid in TgSwDI mice with congophilic amyloid angiopathy (CAA). In the present study, we investigated whether the Aβ12–28P elicits a therapeutic effect on tau-related pathology in addition to amyloid pathology using old triple transgenic Alzheimer’s disease mice (3xTg, with PS1M146V, APPSwe and tauP30IL transgenes) with established pathology from the ages of 21 to 26 months. We show that treatment with Aβ12–28P substantially reduces tau pathology both immunohistochemically and biochemically, as well as reducing the amyloid burden and suppressing the activation of astrocytes and microglia. These affects correlate with a behavioral amelioration in the treated Tg mice. PMID:24117759

  20. Modification by acrolein, a component of tobacco smoke and age-related oxidative stress, mediates functional impairment of human apolipoprotein E.

    PubMed

    Tamamizu-Kato, Shiori; Wong, Jason Yiu; Jairam, Vikram; Uchida, Koji; Raussens, Vincent; Kato, Hiroyuki; Ruysschaert, Jean-Marie; Narayanaswami, Vasanthy

    2007-07-17

    Oxidative damage to proteins such as apolipoprotein B-100 increases the atherogenicity of low-density lipoproteins (LDL). However, little is known about the potential oxidative damage to apolipoprotein E (apoE), an exchangeable antiatherogenic apolipoprotein. ApoE plays an integral role in lipoprotein metabolism by regulating the plasma cholesterol and triglyceride levels. Hepatic uptake of lipoproteins is facilitated by apoE's ability to bind with cell surface heparan sulfate proteoglycans and to lipoprotein receptors via basic residues in its 22 kDa N-terminal domain (NT). We investigated the effect of acrolein, an aldehydic product of endogenous lipid peroxidation and a tobacco smoke component, on the conformation and function of recombinant human apoE3-NT. Acrolein caused oxidative modification of apoE3-NT as detected by Western blot with acrolein-lysine-specific antibodies, and tertiary conformational alterations. Acrolein modification impairs the ability of apoE3-NT to interact with heparin and the LDL receptor. Furthermore, acrolein-modified apoE3-NT displayed a 5-fold decrease in its ability to interact with lipid surfaces. Our data indicate that acrolein disrupts the functional integrity of apoE3, which likely interferes with its role in regulating plasma cholesterol homeostasis. These observations have implications regarding the role of apoE in the pathogenesis of smoking- and oxidative stress-mediated cardiovascular and cerebrovascular diseases.

  1. Protonated nanostructured aluminosilicate (NSAS) reduces plasma cholesterol concentrations and atherosclerotic lesions in Apolipoprotein E deficient mice fed a high cholesterol and high fat diet

    PubMed Central

    Sivak, Olena; Darlington, Jerry; Gershkovich, Pavel; Constantinides, Panayiotis P; Wasan, Kishor M

    2009-01-01

    The aim of this work was to assess the effect of chronic administration of protonated nanostructured aluminosilicate (NSAS) on the plasma cholesterol levels and development of atherosclerotic lesions in Apolipoprotein (ApoE) deficient mice fed a high cholesterol and high fat diet. Apolipoprotein E (ApoE) deficient mice were divided into the following treatment groups: protonated NSAS 1.4% (w/w), untreated control and 2% (w/w) stigmastanol mixed with high-cholesterol/high-fat diet. Animals were treated for 12 weeks, blood samples were withdrawn every 4 weeks for determination of plasma cholesterol and triglyceride levels. At the end of the study the aortic roots were harvested for assessment of atherosclerotic lesions. NSAS at 1.4% (w/w) and stigmastanol at 2% (w/w) treatment groups showed significant decreases in plasma cholesterol concentrations at all time points relative to the control animals. The lesion sum area in 1.4% (w/w) NSAS and 2% (w/w) stigmastanol groups were significantly less from the control animals. In conclusion, in this study, the effectiveness of chronic administration of protonated NSAS material in the reduction of plasma cholesterol levels and decrease in development of atherosclerotic lesions was demonstrated in Apo-E deficient mice model. PMID:19638223

  2. Rescuing cholinergic neurons from apoptotic degeneration by targeting of serotonin modulator-and apolipoprotein E-conjugated liposomes to the hippocampus

    PubMed Central

    Kuo, Yung-Chih; Lee, Yin-Jung

    2016-01-01

    β-Amyloid (Aβ)-targeting liposomes (LIP) with surface serotonin modulator (SM) and apolipoprotein E (ApoE) were utilized to facilitate the delivery of nerve growth factor (NGF) across the blood–brain barrier (BBB) for neuroprotection in the hippocampus. The therapeutic efficacy of SM- and ApoE-grafted LIP carrying NGF (NGF-SM-ApoE-LIP) was assessed by an in vitro Alzheimer’s disease (AD) model of degenerated SK-N-MC cells and an in vivo AD model of Aβ-insulted Wistar rats. The experimental evidences revealed that the modified SM and ApoE on the surface of LIP increased the permeation of NGF across the BBB without serious damage to structural integrity of tight junction. When compared with free NGF, NGF-SM-ApoE-LIP upregulated the expression of phosphorylated neurotrophic tyrosine kinase receptor type 1 on cholinergic neurons and significantly improved their survival. In addition, NGF-SM-ApoE-LIP could reduce the secretion of acetylcholinesterase and malondialdehyde and rescue hippocampal neurons from apoptosis in rat brains. The synergistic effect of SM and ApoE is promising in the induction of NGF to inhibit the neurotoxicity of Aβ and NGF-SM-ApoE-LIP can be a potent antiapoptotic pharmacotherapy for clinical care of patients with AD. PMID:28008255

  3. Potential implications of Apolipoprotein E in early brain injury after experimental subarachnoid hemorrhage: Involvement in the modulation of blood-brain barrier integrity

    PubMed Central

    Peng, Jianhua; Yang, Ping; Kuai, Li; Qin, Xinghu; Cao, Fang; Sun, Xiaochuan; Chen, Ligang; Vitek, Michael P.; Jiang, Yong

    2016-01-01

    Apolipoprotein E (Apoe) genetic polymorphisms have been implicated in the long term outcome of subarachnoid haemorrhage (SAH), but little is known about the effect of Apoe on the early brain injury (EBI) after SAH. This study investigated the potential role of APOE in EBI post-SAH. Multiple techniques were used to determine the early BBB disruption in EBI post-SAH in a murine model using wild-type (WT) and Apoe−/− (KO) mice. Progressive BBB disruption (Evans blue extravasation and T2 hyperintensity in magnetic resonance imaging) was observed before the peak of endogenous APOE expression elevation at 48h after SAH. Moreover, Apoe−/− mice exhibited more severe BBB disruption charcteristics after SAH than WT mice, including higher levels of Evans blue and IgG extravasation, T2 hyperintensity in magnetic resonance imaging, tight junction proteins degradation and endothelial cells death. Mechanistically, we found that APOE restores the BBB integrity in the acute stage after SAH via the cyclophilin A (CypA)-NF-κB-proinflammatory cytokines-MMP-9 signalling pathway. Consequently, although early BBB disruption causes neurological dysfunctions after SAH, we capture a different aspect of the effects of APOE on EBI after SAH that previous studies had overlooked and open up the idea of BBB disruption as a target of APOE-based therapy for EBI amelioration research in the future. PMID:27463015

  4. Baculovirus-mediated expression of human apolipoprotein E in Manduca sexta larvae generates particles that bind to the low density lipoprotein receptor.

    PubMed Central

    Gretch, D G; Sturley, S L; Friesen, P D; Beckage, N E; Attie, A D

    1991-01-01

    Human apolipoprotein E (apoE) is a ligand for the low density lipoprotein (LDL) receptor and mediates the catabolism of several classes of lipoprotein particles. Binding of apoE to the LDL receptor requires association of apoE with lipid in a vesicle or a lipoprotein particle. Because of this requirement, purified apoE or apoE derived directly from bacterial expression systems does not bind to the LDL receptor. To overcome this problem and to facilitate analysis of apoE structure, recombinant baculoviruses containing the human apoE cDNA fused to the polyhedrin promoter of Autographa californica nuclear polyhedrosis virus were constructed. The recombinant viruses were used to infect larvae of the tobacco hornworm Manduca sexta in vivo. High levels of lipoprotein particles containing human apoE were present in the hemolymph of infected larvae. In contrast to apoE produced by recombinant baculovirus-infected insect cells in vitro, these particles were excellent ligands for the LDL receptor. Images PMID:1924311

  5. High-Fat Diet Changes Hippocampal Apolipoprotein E (ApoE) in a Genotype- and Carbohydrate-Dependent Manner in Mice

    PubMed Central

    Lane-Donovan, Courtney; Herz, Joachim

    2016-01-01

    Alzheimer’s disease is a currently incurable neurodegenerative disease affecting millions of individuals worldwide. Risk factors for Alzheimer’s disease include genetic risk factors, such as possession of ε4 allele of apolipoprotein E (ApoE4) over the risk-neutral ApoE3 allele, and lifestyle risk factors, such as diet and exercise. The intersection of these two sources of disease risk is not well understood. We investigated the impact of diet on ApoE levels by feeding wildtype, ApoE3, and ApoE4 targeted replacement (TR) mice with chow, high-fat, or ketogenic (high-fat, very-low-carbohydrate) diets. We found that high-fat diet affected both plasma and hippocampal levels of ApoE in an isoform-dependent manner, with high-fat diet causing a surprising reduction of hippocampal ApoE levels in ApoE3 TR mice. Conversely, the ketogenic diet had no effect on hippocampal ApoE. Our findings suggest that the use of dietary interventions to slow the progression AD should take ApoE genotype into consideration. PMID:26828652

  6. Treatment with bexarotene, a compound that increases apolipoprotein-E, provides no cognitive benefit in mutant APP/PS1 mice

    PubMed Central

    2013-01-01

    Background Though the precise cause(s) of Alzheimer’s disease (AD) remain unknown, there is strong evidence that decreased clearance of β-amyloid (Aβ) from the brain can contribute to the disease. Therapeutic strategies to promote natural Aβ clearance mechanisms, such as the protein apolipoprotein-E (APOE), hold promise for the treatment of AD. The amount of APOE in the brain is regulated by nuclear receptors including retinoid X receptors (RXRs). Drugs that activate RXRs, including bexarotene, can increase APOE and ABCA1 production, and have been shown to decrease the Aβ burden and improve cognition in mouse models of Aβ amyloidosis. Although recent bexarotene studies failed to replicate the rapid clearance of Aβ from brains, behavioral and cognitive effects of this compound remain controversial. Findings In efforts to clarify these behavioral findings, mutant APP/PS1 mice were acutely dosed with bexarotene. While ABCA1 was upregulated in mutant APP/PS1 mice treated with bexarotene, this drug failed to attenuate Aβ plaques or cognitive deficits in these mice. Conclusions We recommend rigorous preclinical study to evaluate the mechanism and utility of such a compound for AD therapy. PMID:23764200

  7. Genetic linkage of hyperglycemia, body weight and serum amyloid-P in an intercross between C57BL/6 and C3H apolipoprotein E-deficient mice.

    PubMed

    Su, Zhiguang; Li, Yuhua; James, Jessica C; Matsumoto, Alan H; Helm, Gregory A; Lusis, Aldons J; Shi, Weibin

    2006-05-15

    Dyslipidemia and hyperglycemia are integral components of the metabolic perturbations in type 2 diabetes. Apolipoprotein E-deficient (apoE(-/-)) mice develop severe hyperlipidemia and significant hyperglycemia when fed a western diet containing 21% fat (w/w), 0.15% cholesterol and 19.5% casein. Using an intercross between C57BL/6J (B6) and C3H/HeJ (C3H) apoE(-/-) mice, we performed quantitative trait locus (QTL) analysis to identify loci contributing to hyperglycemia and associated traits. Fasting plasma levels of glucose, insulin and serum amyloid-P (SAP) and body weight in 234 female F2 mice were measured after being fed the western diet for 12 weeks. QTL analysis revealed one significant QTL, named Bglu3 [95.8 cM, logarithm of odds ratio (OR)(LOD) 4.1], on chromosome 1 and a suggestive QTL on chromosome 9 (38 cM, LOD 2.3) that influenced plasma glucose levels. Bglu3 coincided with loci on distal chromosomal 1 that had a major influence on plasma SAP levels and body weight. Significant correlations between plasma glucose, SAP and body weight were observed in F2 mice. Thus, these results demonstrate genetic linkages of hyperglycemia and body weight with SAP, a marker of the acute-phase response, in hyperlipidemic apoE(-/-) mice and suggest a probability for the Sap gene to be a positional candidate of Bglu3.

  8. High-Fat Diet Changes Hippocampal Apolipoprotein E (ApoE) in a Genotype- and Carbohydrate-Dependent Manner in Mice.

    PubMed

    Lane-Donovan, Courtney; Herz, Joachim

    2016-01-01

    Alzheimer's disease is a currently incurable neurodegenerative disease affecting millions of individuals worldwide. Risk factors for Alzheimer's disease include genetic risk factors, such as possession of ε4 allele of apolipoprotein E (ApoE4) over the risk-neutral ApoE3 allele, and lifestyle risk factors, such as diet and exercise. The intersection of these two sources of disease risk is not well understood. We investigated the impact of diet on ApoE levels by feeding wildtype, ApoE3, and ApoE4 targeted replacement (TR) mice with chow, high-fat, or ketogenic (high-fat, very-low-carbohydrate) diets. We found that high-fat diet affected both plasma and hippocampal levels of ApoE in an isoform-dependent manner, with high-fat diet causing a surprising reduction of hippocampal ApoE levels in ApoE3 TR mice. Conversely, the ketogenic diet had no effect on hippocampal ApoE. Our findings suggest that the use of dietary interventions to slow the progression AD should take ApoE genotype into consideration.

  9. Cigarette-smoke-induced atherogenic lipid profiles in plasma and vascular tissue of apolipoprotein E-deficient mice are attenuated by smoking cessation.

    PubMed

    Lietz, Michael; Berges, An; Lebrun, Stefan; Meurrens, Kris; Steffen, Yvonne; Stolle, Katrin; Schueller, Jutta; Boue, Stephanie; Vuillaume, Grégory; Vanscheeuwijck, Patrick; Moehring, Michaela; Schlage, Walter; De Leon, Hector; Hoeng, Julia; Peitsch, Manuel

    2013-07-01

    Tobacco smoke exerts perturbations on lipid metabolism and arterial cell function that accelerate atherosclerosis. Lipidomics has emerged as a key technology in helping to elucidate the lipid-related mechanisms of atherosclerosis. In this study, we investigated the effects of smoking cessation on plaque development and aortic arch content of various lipid molecular classes and species. Apolipoprotein E-deficient mice were exposed to fresh air (sham) or to mainstream cigarette smoke (CS) for 6 months, or to CS for 3 months followed by sham for 3 months (cessation group). Lipids from plasma and aortic arches, plasma lipoprotein profiles and plaque morphometry measurements were analyzed. We already showed that CS exposure accelerated plaque size and total cholesterol content of the aortic arch at 3 and 6 months. Marked increases were seen in the relative enrichment of cholesteryl esters, phospholipids, sphingomyelins, and glycosphingolipids. Smoking cessation slowed plaque progression and resulted in lower levels of many lipid species in plasma and aortic arch. While CS exposure promoted rapid lipid accumulation in mouse aorta, smoking cessation translated into a slow removal of lipids from the vessel wall. Despite the smoking cessation-dependent metabolic changes leading to increased animal body weight, accumulation of proatherogenic lipids in the vessel was halted after exposure cessation, indicating that the clinical benefits of smoking cessation translate directly to the vessel wall and its lipid makeup.

  10. Deficiency of cyclin-dependent kinase inhibitors p21{sup Cip1} and p27{sup Kip1} accelerates atherogenesis in apolipoprotein E-deficient mice

    SciTech Connect

    Akyuerek, Levent M.; Boehm, Manfred; Olive, Michelle; Zhou, Alex-Xianghua; San, Hong; Nabel, Elizabeth G.

    2010-05-28

    Cyclin-dependent kinase inhibitors, p21{sup Cip1} and p27{sup Kip1}, are upregulated during vascular cell proliferation and negatively regulate growth of vascular cells. We hypothesized that absence of either p21{sup Cip1} or p27{sup Kip1} in apolipoprotein E (apoE)-deficiency may increase atherosclerotic plaque formation. Compared to apoE{sup -/-} aortae, both apoE{sup -/-}/p21{sup -/-} and apoE{sup -/-}/p27{sup -/-} aortae exhibited significantly more atherosclerotic plaque following a high-cholesterol regimen. This increase was particularly observed in the abdominal aortic regions. Deficiency of p27{sup Kip1} accelerated plaque formation significantly more than p21{sup -/-} in apoE{sup -/-} mice. This increased plaque formation was in parallel with increased intima/media area ratios. Deficiency of p21{sup Cip1} and p27{sup Kip1} accelerates atherogenesis in apoE{sup -/-} mice. These findings have significant implications for our understanding of the molecular basis of atherosclerosis associated with excessive proliferation of vascular cells.

  11. Fucoidan alleviates high-fat diet-induced dyslipidemia and atherosclerosis in ApoE(shl) mice deficient in apolipoprotein E expression.

    PubMed

    Yokota, Takashi; Nomura, Koichi; Nagashima, Mikio; Kamimura, Naomi

    2016-06-01

    Fucoidan, a sulfated polysaccharide extracted from brown seaweeds, possesses many biological activities including anti-inflammatory and antioxidant activities. We aimed to investigate the protective effects of fucoidan on dyslipidemia and atherosclerosis in apolipoprotein E-deficient mice (ApoE(shl) mice) and to elucidate its molecular targets in the liver by using a transcriptomic approach. For 12weeks, ApoE(shl) mice were fed a high-fat diet (HFD) supplemented with either 1% or 5% fucoidan. Fucoidan supplementation significantly reduced tissue weight (liver and white adipose tissue), blood lipid, total cholesterol (TC), triglyceride (TG), non-high-density lipoprotein cholesterol (non-HDL-C) and glucose levels in HFD-fed ApoE(shl) mice but increased plasma lipoprotein lipase (LPL) activity and HDL-C levels. Fucoidan also reduced hepatic steatosis levels (liver size, TC and TG levels, and lipid peroxidation) and increased white adipose tissue LPL activity. DNA microarray analysis and quantitative reverse transcription-polymerase chain reaction demonstrated differential expression of genes encoding proteins involved in lipid metabolism, energy homeostasis and insulin sensitivity, by activating Ppara and inactivating Srebf1. Fucoidan supplementation markedly reduced the thickness of the lipid-rich plaque, lipid peroxidation and foaming macrophage accumulation in the aorta in HFD-fed ApoE(shl) mice. Thus, fucoidan supplementation appears to have anti-dyslipidemic and anti-atherosclerotic effects by inducing LPL activity and inhibiting the effects of inflammation and oxidative stress in HFD-fed ApoE(shl) mice.

  12. Gender difference in apolipoprotein E-associated risk for familial Alzheimer disease: a possible clue to the higher incidence of Alzheimer disease in women.

    PubMed Central

    Payami, H.; Zareparsi, S.; Montee, K. R.; Sexton, G. J.; Kaye, J. A.; Bird, T. D.; Yu, C. E.; Wijsman, E. M.; Heston, L. L.; Litt, M.; Schellenberg, G. D.

    1996-01-01

    Late-onset Alzheimer disease (AD) is associated with the apolipoprotein E (APOE)-epsilon4 allele. In late-onset familial AD, women have a significantly higher risk of developing the disease than do men. The aim of this study was to determine whether the gender difference in familial AD is a function of APOE genotype. We studied 58 late-onset familial AD kindreds. Kaplan-Meier survival analysis was used to assess genotype-specific distributions of age at onset. Odds ratios were estimated by logistic regression with adjustment for age and by conditional logistic regression with stratification on families. All methods detected a significant gender difference for the epsilon4 heterozygous genotype. In women, epsilon4 heterozygotes had higher risk than those without epsilon4; there was no significant difference between epsilon4 heterozygotes and epsilon4 homozygotes. In men, epsilon4 heterozygotes had lower risk than epsilon4 homozygotes; there was not significant difference between epsilon4 heterozygotes and those without epsilon4. A direct comparison of epsilon4 heterozygous men and women revealed a significant twofold increased risk in women. We confirmed these results in 15 autopsy-confirmed AD kindreds from the National Cell Repository at Indiana University Alzheimer Disease Center. These observations are consistent with the increased incidence of familial AD in women and may be a critical clue to the role of gender in the pathogenesis of AD. PMID:8644745

  13. Gender difference in apolipoprotein E-associated risk for familial Alzheimer disease: A possible clue to the higher incidence of Alzheimer disease in women

    SciTech Connect

    Payami, H.; Zareparsi, S.; Montee, K.R.; Litt, M.

    1996-04-01

    Late-onset Alzheimer disease (AD) is associated with the apolipoprotein E (APOE)-{epsilon}4 allele. In late-onset familial AD, women have a significantly higher risk of developing the disease than do men. The aim of this study was to determine whether the gender difference in familial AD is a function of APOE genotype. We studied 58 late-onset familial AD kindreds. Kaplan-Meier survival analysis was used to assess genotype-specific distributions of age at onset. Odds ratios were estimated by logistic regression with adjustment for age and by conditional logistic regression with stratification on families. All methods detected a significant gender difference for the {epsilon}4 heterozygous genotype. In women, {epsilon}4 heterozygotes had higher risk than those without {epsilon}4; there was no significant difference between {epsilon}4 heterozygotes and {epsilon}4 homozygotes. In men, {epsilon}4 heterozygotes had lower risk than {epsilon}4 homozygotes; there was no significant difference between {epsilon}4 heterozygotes and those without {epsilon}4. A direct comparison of {epsilon}4 heterozygous men and women revealed a significant two-fold increased risk in women. We confirmed these results in 15 autopsy-confirmed AD kindreds from the National Cell Repository at Indiana University Alzheimer Disease Center. These observations are consistent with the increased incidence of familial AD in women and may be a critical clue to the role of gender in the pathogenesis of AD. 53 refs., 2 figs., 2 tabs.

  14. A prospective study of cognitive health in the elderly (Oregon Brain Aging Study): effects of family history and apolipoprotein E genotype.

    PubMed Central

    Payami, H; Grimslid, H; Oken, B; Camicioli, R; Sexton, G; Dame, A; Howieson, D; Kaye, J

    1997-01-01

    The oldest old are the fastest-growing segment of our population and have the highest prevalence of dementia. Little is known about the genetics of cognitive health in the very old. The aim of this study was to determine whether the genetic risk factors for Alzheimer disease (AD)--namely, apolipoprotein E (APOE) epsilon4 allele and a family history of dementia-continue to be important factors in the cognitive health of the very old. Case-control studies suggest that the effect of genetic factors diminishes at age >75 years. The present prospective study provided evidence to the contrary. We studied 114 Caucasian subjects who were physically healthy and cognitively intact at age 75 years and who were followed, for an average of 4 years, with neurological, psychometric, and neuroimaging examinations. Excellent health at entry did not protect against cognitive decline. Incidence of cognitive decline rose sharply with age. epsilon4 and a family history of dementia (independent of epsilon4) were associated with an earlier age at onset of dementia. Subjects who had epsilon4 or a family history of dementia had a ninefold-higher age-specific risk for dementia than did those who had neither epsilon4 nor a family history of dementia. These observations suggest that the rate of cognitive decline increases with age and that APOE and other familial/genetic factors influence the onset age throughout life. PMID:9106542

  15. Tanshinone II A stabilizes vulnerable plaques by suppressing RAGE signaling and NF-κB activation in apolipoprotein-E-deficient mice

    PubMed Central

    Zhao, Dong; Tong, Lufang; Zhang, Lixin; Li, Hong; Wan, Yingxin; Zhang, Tiezhong

    2016-01-01

    Tanshinone II A (TSIIA) is a diterpene quinone extracted from the roots of Salvia miltiorrhiza with anti-inflammatory and anti-oxidant properties that is used to treat atherosclerosis. In the current study, morphological analyses were conducted to evaluate the effects of TSIIA on atherosclerotic vulnerable plaque stability. Additionally, receptor of advanced glycation end products (RAGE), adhesion molecule, and matrix-metalloproteinases (MMPs) expression, and nuclear factor-κB (NF-κB) activation were examined in apolipoprotein E (apoE)-deficient mice treated with TSIIA. Eight-week-old apoE−/− mice were administered TSIIA and fed an atherogenic diet for 8 weeks. TSIIA exhibited no effects on plaque size. Analysis of the vulnerable plaque composition demonstrated decreased numbers of macrophages and smooth muscle cells, and increased collagen content in apoE-deficient mice treated with TSIIA compared with untreated mice. Western blotting revealed that TSIIA downregulated the expression levels of vascular cellular adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and MMP-2, −3, and −9, suppressed RAGE, and inhibited NF-κB, JNK and p38 activation. The present study demonstrated that the underlying mechanism of TSIIA stabilization of vulnerable plaques involves interfering with RAGE and NF-κB activation, and downregulation of downstream inflammatory factors, including ICAM-1, VCAM-1, and MMP-2, −3 and −9 in apoE−/− mice. PMID:27840935

  16. A prospective study of cognitive health in the elderly (Oregon Brain Aging Study): effects of family history and apolipoprotein E genotype.

    PubMed

    Payami, H; Grimslid, H; Oken, B; Camicioli, R; Sexton, G; Dame, A; Howieson, D; Kaye, J

    1997-04-01

    The oldest old are the fastest-growing segment of our population and have the highest prevalence of dementia. Little is known about the genetics of cognitive health in the very old. The aim of this study was to determine whether the genetic risk factors for Alzheimer disease (AD)--namely, apolipoprotein E (APOE) epsilon4 allele and a family history of dementia-continue to be important factors in the cognitive health of the very old. Case-control studies suggest that the effect of genetic factors diminishes at age >75 years. The present prospective study provided evidence to the contrary. We studied 114 Caucasian subjects who were physically healthy and cognitively intact at age 75 years and who were followed, for an average of 4 years, with neurological, psychometric, and neuroimaging examinations. Excellent health at entry did not protect against cognitive decline. Incidence of cognitive decline rose sharply with age. epsilon4 and a family history of dementia (independent of epsilon4) were associated with an earlier age at onset of dementia. Subjects who had epsilon4 or a family history of dementia had a ninefold-higher age-specific risk for dementia than did those who had neither epsilon4 nor a family history of dementia. These observations suggest that the rate of cognitive decline increases with age and that APOE and other familial/genetic factors influence the onset age throughout life.

  17. Interactive effects of apolipoprotein e4 and diabetes risk on later myelinating white matter regions in neurologically healthy older aged adults

    PubMed Central

    Foley, Jessica M.; Salat, David H.; Stricker, Nikki H.; Zink, Tyler A.; Grande, Laura J.; McGlinchey, Regina E.; Milberg, William P.; Leritz, Elizabeth C.

    2014-01-01

    Possession of the apolipoprotein e4 (APOE4) allele and diabetes risk are independently related to reduced white matter (WM) integrity that may contribute to the development of Alzheimer's disease (AD). The purpose of this study is to examine the interactive effects of APOE4 and diabetes risk on later myelinating WM regions among healthy elderly at risk for AD. A sample of 107 healthy elderly (80 APOE4−/27 APOE4+) underwent structural MRI/ DTI data were prepared using TBSS and a-priori ROIs were extracted from T1-based WM parcellations. ROIs included later myelinating frontal/temporal/parietal WM regions and control regions, measured by fractional anisotropy (FA). There were no APOE group differences on DTI for any ROI. Within the APOE4 group, we found negative relationships between HAIC/fasting glucose and APOE4 on FA for all later myelinating WM regions, but not for early/middle myelinating control regions. Results also showed APOE4/diabetes risk interactions for WM underlying supramarginal, superior temporal, precuneus, superior parietal, and superior frontal regions. Results suggest interactive effects of APOE4 and diabetes risk on later myelinating WM regions, which supports preclinical detection of AD among this particularly susceptible subgroup. PMID:24381137

  18. Apolipoprotein E isoforms 3/3 and 3/4 differentially interact with circulating stearic, palmitic, and oleic fatty acids and lipid levels in Alaskan Natives.

    PubMed

    Castellanos-Tapia, Lyssia; López-Alvarenga, Juan Carlos; Ebbesson, Sven O E; Ebbesson, Lars O E; Tejero, M Elizabeth

    2015-04-01

    Lifestyle changes in Alaskan Natives have been related to the increase of cardiovascular disease and metabolic syndrome in the last decades. Variation of the apolipoprotein E (Apo E) genotype may contribute to the diverse response to diet in lipid metabolism and influence the association between fatty acids in plasma and risk factors for cardiovascular disease. The aim of this investigation was to analyze the interaction between Apo E isoforms and plasma fatty acids, influencing phenotypes related to metabolic diseases in Alaskan Natives. A sample of 427 adult Siberian Yupik Alaskan Natives was included. Fasting glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, Apo A1, and Apo B plasma concentrations were measured using reference methods. Concentrations of 13 fatty acids in fasting plasma were analyzed by gas chromatography, and Apo E variants were identified. Analyses of covariance were conducted to identify Apo E isoform and fatty acid main effects and multiplicative interactions. The means for body mass index and age were 26 ± 5.2 and 47 ± 1.5, respectively. Significant main effects were observed for variation in Apo E and different fatty acids influencing Apo B levels, triglycerides, and total cholesterol. Significant interactions were found between Apo E isoform and selected fatty acids influencing total cholesterol, triglycerides, and Apo B concentrations. In summary, Apo E3/3 and 3/4 isoforms had significant interactions with circulating levels of stearic, palmitic, oleic fatty acids, and phenotypes of lipid metabolism in Alaskan Natives.

  19. The pathological cross talk between apolipoprotein E and amyloid-beta peptide in Alzheimer's disease: emerging gene-based therapeutic approaches.

    PubMed

    Iurescia, Sandra; Fioretti, Daniela; Mangialasche, Francesca; Rinaldi, Monica

    2010-01-01

    Apolipoprotein E (ApoE) plays a key role in lipid transport in the plasma and in the central nervous system through its interaction with members of the low-density lipoprotein receptor family. The three common isoforms of ApoE (ApoE2, ApoE3, and ApoE4) differ in their ability to perform neuronal maintenance and repair functions and differentially affect the risk of developing neurodegenerative disorders. The ApoE4 isoform is a strong genetic risk factor for Alzheimer's disease. Up-to-date knowledge about the structural and biophysical features of ApoE4 shed light on the molecular basis underlying the isoform-specific pathogenic role of ApoE4 and its contribution to AD pathology through several different mechanisms. ApoE4 impacts on amyloid-beta (Abeta) production, Abeta clearance, Abeta fibrillation, and tangle formation as well as on mitochondrial functions leading to neuronal toxicity and synaptic damage. This review summarizes the pathological cross talk between ApoE and Abeta peptide in Alzheimer's disease. Lastly, we examine emerging gene-based therapeutic approaches encompassing the use of ApoE and their potential opportunities to preventing or treating Alzheimer's disease.

  20. Molecular structure investigation of neutral, dimer and anion forms of 3,4-pyridinedicarboxylic acid: a combined experimental and theoretical study.

    PubMed

    Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

    2015-01-25

    In this study, the structural and vibrational analysis of 3,4-pyridinedicarboxylic acid (3,4-PDCA) are presented using experimental techniques as FT-IR, FT-Raman, NMR, UV and quantum chemical calculations. FT-IR and FT-Raman spectra of 3,4-pyridinedicarboxylic acid in the solid phase are recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1), respectively. The geometrical parameters and energies of all different and possible monomer, dimer, anion(-1) and anion(-2) conformers of 3,4-PDCA are obtained from Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) basis set. There are sixteen conformers (C1C16) for this molecule (neutral form). The most stable conformer of 3,4-PDCA is the C1 conformer. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with scaled quantum mechanics (SQM) method. (1)H and (13)C NMR spectra are recorded and the chemical shifts are calculated by using DFT/B3LYP methods with 6-311++G(d,p) basis set. The UV absorption spectrum of the studied compound is recorded in the range of 200-400 nm by dissolved in ethanol. The optimized geometric parameters were compared with experimental data via the X-ray results derived from complexes of this molecule. In addition these, molecular electrostatic potential (MEP), thermodynamic and electronic properties, HOMO-LUMO energies and Mulliken atomic charges, are performed.

  1. Molecular structure investigation of neutral, dimer and anion forms of 3,4-pyridinedicarboxylic acid: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

    2015-01-01

    In this study, the structural and vibrational analysis of 3,4-pyridinedicarboxylic acid (3,4-PDCA) are presented using experimental techniques as FT-IR, FT-Raman, NMR, UV and quantum chemical calculations. FT-IR and FT-Raman spectra of 3,4-pyridinedicarboxylic acid in the solid phase are recorded in the region 4000-400 cm-1 and 4000-50 cm-1, respectively. The geometrical parameters and energies of all different and possible monomer, dimer, anion-1 and anion-2 conformers of 3,4-PDCA are obtained from Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) basis set. There are sixteen conformers (C1sbnd C16) for this molecule (neutral form). The most stable conformer of 3,4-PDCA is the C1 conformer. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with scaled quantum mechanics (SQM) method. 1H and 13C NMR spectra are recorded and the chemical shifts are calculated by using DFT/B3LYP methods with 6-311++G(d,p) basis set. The UV absorption spectrum of the studied compound is recorded in the range of 200-400 nm by dissolved in ethanol. The optimized geometric parameters were compared with experimental data via the X-ray results derived from complexes of this molecule. In addition these, molecular electrostatic potential (MEP), thermodynamic and electronic properties, HOMO-LUMO energies and Mulliken atomic charges, are performed.

  2. Mechanism of FGF receptor dimerization and activation

    NASA Astrophysics Data System (ADS)

    Sarabipour, Sarvenaz; Hristova, Kalina

    2016-01-01

    Fibroblast growth factors (fgfs) are widely believed to activate their receptors by mediating receptor dimerization. Here we show, however, that the FGF receptors form dimers in the absence of ligand, and that these unliganded dimers are phosphorylated. We further show that ligand binding triggers structural changes in the FGFR dimers, which increase FGFR phosphorylation. The observed effects due to the ligands fgf1 and fgf2 are very different. The fgf2-bound dimer structure ensures the smallest separation between the transmembrane (TM) domains and the highest possible phosphorylation, a conclusion that is supported by a strong correlation between TM helix separation in the dimer and kinase phosphorylation. The pathogenic A391E mutation in FGFR3 TM domain emulates the action of fgf2, trapping the FGFR3 dimer in its most active state. This study establishes the existence of multiple active ligand-bound states, and uncovers a novel molecular mechanism through which FGFR-linked pathologies can arise.

  3. The Association of Hepatitis C Virus Glycoproteins with Apolipoproteins E and B Early in Assembly Is Conserved in Lipoviral Particles*

    PubMed Central

    Boyer, Audrey; Dumans, Amélie; Beaumont, Elodie; Etienne, Loïc; Roingeard, Philippe; Meunier, Jean-Christophe

    2014-01-01

    In patients chronically infected with hepatitis C virus and in the HCV cell culture system (HCVcc), it is known that highly infectious virus particles have low to very low buoyant densities. These low densities have been attributed to the association of HCV with lipoprotein components, which occur during the viral morphogenesis. The resulting hybrid particles are known as lipoviral particles (LVP); however, very little is known about how these particles are created. In our study, we used Huh7.5 cells to investigate the intracellular association between envelope proteins and apolipoproteins B and E (ApoB and ApoE, respectively). In particular, we were interested in the role of this association in initiating LVP morphogenesis. Co-immunoprecipitation assays revealed that ApoB, ApoE, and HCV glycoproteins formed a protein complex early in the HCV lifecycle. Confocal analyses of naïve, E1E2-transduced and HCVcc-infected cells showed that HCV glycoproteins, ApoB and ApoE were found strongly colocalized only in the endoplasmic reticulum. We also found that HCV glycoproteins, ApoB and ApoE were already associated with intracellular infectious viral particles and, furthermore, that the protein complex was conserved in the infectious viral particles present in the supernatant of infected Huh7.5 cells. The association of HCV glycoproteins with ApoE was also evidenced in the HCVpp system, using the non-hepatic HEK293T cell line. We suggest that the complex formed by HCV E1E2, ApoB, and ApoE may initiate lipoviral particle morphogenesis. PMID:24838241

  4. 4Ca2+.troponin C forms dimers in solution at neutral pH that dissociate upon binding various peptides: small-angle X-ray scattering studies of peptide-induced structural changes.

    PubMed

    Blechner, S L; Olah, G A; Strynadka, N C; Hodges, R S; Trewhella, J

    1992-11-24

    Small-angle X-ray scattering data have been measured for rabbit skeletal muscle troponin C and its complexes with the venom peptides melittin and mastoparan as well as synthetic peptides based on regions of the troponin I sequence implicated in troponin C binding. At the neutral pH used in this study (pH 6.8), troponin C shows a tendency to form dimers in the presence of 4 mol equiv of Ca2+, but is monomeric in solution when 2 or less mol equiv of Ca2+ is present. The 4Ca2+.troponin C dimers dissociate upon binding melittin, mastoparan, and peptides based on residues 96-115, 1-30, and 1-40 in the troponin I sequence. This result suggests that the peptide-binding sites overlap with the regions of contact between troponin C molecules forming a dimer. Like the structurally homologous calcium-binding protein calmodulin, troponin C shows conformational flexibility upon binding different peptides. Upon binding melittin, troponin C contracts in a similar manner to calmodulin when it binds peptides known to form amphiphilic helices (e.g., melittin, mastoparan, or MLCK-I). In contrast, mastoparan binding to troponin C does not result in a contracted structure. The scattering data indicate troponin C also remains in an extended structure upon binding the inhibitory peptides having the same sequence as residues 96-115 in troponin I.

  5. Quantitative Trait Loci Affecting Atherosclerosis at the Aortic Root Identified in an Intercross between DBA2J and 129S6 Apolipoprotein E-Null Mice

    PubMed Central

    Kayashima, Yukako; Tomita, Hirofumi; Zhilicheva, Svetlana; Kim, Shinja; Kim, Hyung-Suk; Bennett, Brian J.; Maeda, Nobuyo

    2014-01-01

    Apolipoprotein E-null mice on a DBA/2J genetic background (DBA-apoE) are highly susceptible to atherosclerosis in the aortic root area compared with those on a 129S6 background (129-apoE). To explore atherosclerosis-responsible genetic regions, we performed a quantitative trait locus (QTL) analysis using 172 male and 137 female F2 derived from an intercross between DBA-apoE and 129-apoE mice. A genome-wide scan identified two significant QTL for the size of lesions at the root: one is Ath44 on Chromosome (Chr) 1 at 158 Mb, and the other Ath45 on Chr 2 at 162 Mb. Ath44 co-localizes with but appears to be independent of a previously reported QTL, Ath1, while Ath45 is a novel QTL. DBA alleles of both Ath44 and Ath45 confer atherosclerosis-susceptibility. In addition, a QTL on Chr 14 at 73 Mb was found significant only in males, and 129 allele conferring susceptibility. Further analysis detected female-specific interactions between a second QTL on Chr 1 at 73 Mb and a QTL on Chr 3 at 21 Mb, and between Chr 7 at 84 Mb and Chr 12 at 77 Mb. These loci for the root atherosclerosis were independent of QTLs for plasma total cholesterol and QTLs for triglycerides, but a QTL for HDL (Chr 1 at 126 Mb) overlapped with the Ath44. Notably, haplotype analysis among 129S6, DBA/2J and C57BL/6 genomes and their gene expression data narrowed the candidate regions for Ath44 and Ath45 to less than 5 Mb intervals where multiple genome wide associations with cardiovascular phenotypes have also been reported in humans. SNPs in or near Fmo3, Sele and Selp for Ath44, and Lbp and Pkig for Ath45 were suggested for further investigation as potential candidates underlying the atherosclerosis susceptibility. PMID:24586312

  6. Greater impact of dietary fat manipulation than apolipoprotein E genotype on ex vivo cytokine production - insights from the SATgenε study.

    PubMed

    Koutsos, Athanasios; Jackson, Kim G; Lockyer, Stacey; Carvalho-Wells, Andrew; Minihane, Anne M; Lovegrove, Julie A

    2014-04-01

    Apolipoprotein E (APOE) genotype is believed to play an important role in cardiovascular risk. APOE4 carriers have been associated with higher blood lipid levels and a more pro-inflammatory state compared with APOE3/E3 individuals. Although dietary fat composition has been considered to modulate the inflammatory state in humans, very little is known about how APOE genotype can impact on this response. In a follow-up to the main SATgenε study, we aimed to explore the effects of APOE genotype, as well as, dietary fat manipulation on ex vivo cytokine production. Blood samples were collected from a subset of SATgenε participants (n=52/88), prospectively recruited according to APOE genotype (n=26 E3/E3 and n=26 E3/E4) after low-fat (LF), high saturated fat (HSF) and HSF with 3.45g docosahexaenoic acid (DHA) dietary periods (each diet eight weeks in duration assigned in the same order) for the measurement of ex vivo cytokine production using whole blood culture (WBC). Concentrations of IL-1beta, IL-6, IL-8, IL-10 and TNF-alpha were measured in WBC supernatant samples after stimulation for 24h with either 0.05 or 1μg/ml of bacterial lipopolysaccharide (LPS). Cytokine levels were not influenced by genotype, whereas, dietary fat manipulation had a significant impact on TNF-α and IL-10 production; TNF-α concentration was higher after consumption of the HSF diet compared with baseline and the LF diet (P<0.05), whereas, IL-10 concentration was higher after the LF diet compared with baseline (P<0.05). In conclusion, our study has revealed the amount and type of dietary fat can significantly modulate the production of TNF-α and IL-10 by ex vivo LPS-stimulated WBC samples obtained from normolipidaemic subjects.

  7. ACAT inhibitor pactimibe sulfate (CS-505) reduces and stabilizes atherosclerotic lesions by cholesterol-lowering and direct effects in apolipoprotein E-deficient mice.

    PubMed

    Terasaka, Naoki; Miyazaki, Atsuhiro; Kasanuki, Naomi; Ito, Kayoko; Ubukata, Naoko; Koieyama, Tadashi; Kitayama, Ken; Tanimoto, Tatsuo; Maeda, Naoyuki; Inaba, Toshimori

    2007-02-01

    The objective of the present study was to determine whether a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, pactimibe sulfate (CS-505), could reduce atherosclerotic lesions beyond and independent of the reduction achieved by cholesterol lowering alone from two different types of lesions. (1) Early lesion model. Twelve-week-old apolipoprotein E (apoE)(-/-) mice were treated with 0.03 or 0.1% (w/w) CS-505, 0.1 or 0.3% avasimibe (CI-1011), or 3% cholestyramine for 12 weeks. Each treatment significantly reduced plasma cholesterol by a similar degree (43-48%). The antiatherosclerotic activity of 0.1% CS-505, however, was more efficacious than the effects of the other treatments (90% versus 40-50%). (2) Advanced lesion model. Twenty-four-week-old apoE(-/-) mice were treated with 0.03 or 0.1% CS-505 or 0.1% CI-1011 for 12 weeks. CS-505 at 0.1% revealed enhanced lesion reduction compared with 0.1% CI-1011 (77% versus 54%), whereas the plasma cholesterol-lowering effect of 0.1% CS-505 was almost the same as that of 0.1% CI-1011. Furthermore, immunohistochemical analysis demonstrated that CS-505 significantly reduced the number of macrophages and expression of matrix metalloproteinase (MMP)-2, MMP-9, and MMP-13. These data indicate that CS-505 can reduce and stabilize atherosclerotic lesions. This antiatherosclerotic activity is exerted via both cholesterol lowering and direct ACAT inhibition in plaque macrophages.

  8. Attenuation of apoptosis by telmisartan in atherosclerotic plaques of apolipoprotein E-/- mice: evaluation using technetium 99m-annexin A5.

    PubMed

    Zhao, Yan; Zhao, Songji; Kuge, Yuji; Strauss, H William; Blankenberg, Francis G; Tamaki, Nagara

    2013-01-01

    Technetium 99m (99mTc)-annexin A5, a marker of ongoing apoptosis, is supposed to be useful in the detection of metabolically active atheroma. The aim of this study was to determine the potential of 99mTc-annexin A5 for evaluating the therapeutic effects of an angiotensin II receptor type 1 blocker (ARB) (telmisartan) on atherosclerosis. Male apolipoprotein E-/- mice were divided into telmisartan-treated (3 mg/kg/d, n  =  10) and control (n  =  10) groups. After 16 to 21 weeks of treatment, 99mTc-annexin A5 was injected and cryostat sections of aortic tissues (n  =  10-12/aorta) were prepared. The 99mTc-annexin A5 accumulation level in the plaques was evaluated by autoradiography. Serial sections of the plaques were histologically examined to identify the lesion phenotypes (normal vessels, early lesions, atheromatous lesions, and fibrotic lesions), plaque size, macrophage infiltration levels, and lipid deposition levels. Telmisartan treatment significantly decreased the plaque size (0.05 ± 0.05 vs 0.11 ± 0.08, mm2), macrophage infiltration level (0.02 ± 0.02 vs 0.03 ± 0.02, mm2), lipid deposition level (0.01 ± 0.01 vs 0.02 ± 0.02, mm2), and 99mTc-annexin A5 accumulation level (1.30 ± 1.09 vs 2.15 ± 1.91, × 10-6/g). 99mTc-annexin A5 accumulation levels in the plaques positively correlated with macrophage infiltration (r  =  .69, p < .05) and lipid deposition (r  =  .66, p < .05) levels. Apoptosis imaging with 99mTc-annexin A5 may be useful for evaluating the therapeutic effects of ARBs on atherosclerosis.

  9. Comparative study of apolipoprotein-E polymorphism and plasma lipid levels in dyslipidemic and asymptomatic subjects, and their implication in cardio/cerebro-vascular disorders.

    PubMed

    Ferreira, Cláudia N; Carvalho, Maria G; Fernandes, Ana P S M; Lima, Luciana M; Loures-Valle, Andréia A; Dantas, Julizar; Janka, Zoltán; Palotás, András; Sousa, Marinez O

    2010-01-01

    Polymorphisms in the apolipoprotein-E (apoE) gene may modulate lipoprotein metabolism at different steps and influence total and low density lipoprotein (LDL) cholesterol (LDLc) levels, as well as other lipid features. Population studies have documented significant differences in the frequency of apoE alleles which are related to the prevalence of various cardio-vascular and neuro-psychiatric diseases. In this study, the apoE genotypes and allele frequencies were analyzed in 216 individuals (109 dyslipidemic and 107 normo-lipidic subjects), and the relative contribution of apoE polymorphism on plasma lipid and lipoprotein levels, as well as risk factors was evaluated. In normo-lipidic volunteers, the frequencies of epsilon2, epsilon3 and epsilon4 alleles were 0.042, 0.832 and 0.126, while in dyslipidemic subjects 0.046, 0.835 and 0.119, respectively. No significant difference was observed among epsilon2, epsilon3 or epsilon4 and plasma lipid-lipoprotein levels in the dyslipidemic group. In normo-lipidemics, however, total cholesterol, LDLc and non-HDLc plasma levels were significantly lower in epsilon2 subjects when compared to epsilon3 and epsilon4 individuals. The allelic frequencies of apoE epsilon2, epsilon3 and epsilon4 were similar in dyslipidemic and normo-lipemic subjects, suggesting that apoE polymorphisms have no effect on plasma lipid-lipoprotein levels in dyslipidemic subjects. In contrast, in normo-lipemic subjects the epsilon2 allele showed to be associated with lower total cholesterol and LDLc levels, the mark of a better lipid profile. Depending on other co-existing factors, the epsilon2 allele, therefore, may play either a protective or pathogenic role. This elementary knowledge is a fundamental prerequisite for a possible diagnostic application of these lipoproteins as biomarkers to predict adverse cardio-vascular and/or neuro-psychiatric maladies.

  10. Baicalin inhibits the expression of monocyte chemoattractant protein-1 and interleukin-6 in the kidneys of apolipoprotein E-knockout mice fed a high cholesterol diet.

    PubMed

    Liu, Lihua; Liao, Pingping; Wang, Bin; Fang, Xin; Li, Wei; Guan, Siming

    2015-05-01

    Hyperlipidemia is considered an independent risk factor for renal dysfunction and induces a significant increase in the expression of inflammatory mediators, which can be used to evaluate the degree of renal injury. Baicalin is widely used in traditional Chinese herbal medicine and has multiple pharmacological effects. The present study investigated whether baicalin can attenuate the expression of vascular cell adhesion molecule 1 (VCAM‑1) via a reduction in the expression of monocyte chemoattractant protein‑1 (MCP‑1) and interleukin‑6 (IL‑6) in the kidney of apolipoprotein E (ApoE)‑knockout (KO) mice fed a high cholesterol diet. These mice were used as a model of atherosclerosis and were treated with baicalin (100 mg/kg/day) daily by gavage for a period of 12 weeks. By contrast, wild‑type male C57BL/6J mice were fed a standard diet. Blood samples were obtained from the angular veins of the mice to measure the total cholesterol (TC) and the expression levels of VCAM‑1, MCP‑1 and IL‑6 in the kidney tissues of the mice were analyzed using reverse transcription quantitative polymerase chain reaction and western blot analysis. Following oral administration of baicalin, no significant difference was observed in the TC in the baicalin group compared with the high cholesterol diet control group. The TC was significantly higher in the AopE‑KO mice compared with the wild‑type male C57BL/6J mice. The expression levels of VCAM‑1, MCP‑1 and IL‑6 in the kidney tissues of the baicalin group were lower compared with those in the high cholesterol diet control group. The results suggested that baicalin decreased the expression levels of pro‑inflammatory mediators and prevented kidney dysfunction in the ApoE‑KO mice fed a high cholesterol diet.

  11. H1-antihistamines exacerbate high-fat diet-induced hepatic steatosis in wild-type but not in apolipoprotein E knockout mice

    PubMed Central

    Raveendran, Vineesh V.; Kassel, Karen M.; Smith, Donald D.; Luyendyk, James P.; Williams, Kurt J.; Cherian, Rachel; Reed, Gregory A.; Flynn, Colleen A.; Csanaky, Iván L.; Lickteig, Andrew L.; Pratt-Hyatt, Matthew J.; Klaassen, Curtis D.

    2014-01-01

    We examined the effects of two over-the-counter H1-antihistamines on the progression of fatty liver disease in male C57Bl/6 wild-type and apolipoprotein E (ApoE)−/− mice. Mice were fed a high-fat diet (HFD) for 3 mo, together with administration of either cetirizine (4 mg/kg body wt) or fexofenadine (40 mg/kg body wt) in drinking water. Antihistamine treatments increased body weight gain, gonadal fat deposition, liver weight, and hepatic steatosis in wild-type mice but not in ApoE−/− mice. Lobular inflammation, acute inflammation, and necrosis were not affected by H1-antihistamines in either genotype. Serum biomarkers of liver injury tended to increase in antihistamine-treated wild-type mice. Serum level of glucose was increased by fexofenadine, whereas lipase was increased by cetirizine. H1-antihistamines reduced the mRNA expression of ApoE and carbohydrate response element-binding protein in wild-type mice, without altering the mRNA expression of sterol regulatory element-binding protein 1c, fatty acid synthase, or ApoB100, in either genotype. Fexofenadine increased both triglycerides and cholesterol ester, whereas cetirizine increased only cholesterol ester in liver, with a concomitant decrease in serum triglycerides by both antihistamines in wild-type mice. Antihistamines increased hepatic levels of conjugated bile acids in wild-type mice, with the effect being significant in fexofenadine-treated animals. The increase was associated with changes in the expression of organic anion transport polypeptide 1b2 and bile salt export pump. These results suggest that H1-antihistamines increase the progression of fatty liver disease in wild-type mice, and there seems to be an association between the severity of disease, presence of ApoE, and increase in hepatic bile acid levels. PMID:24852568

  12. Intermedin1–53 Protects Against Myocardial Fibrosis by Inhibiting Endoplasmic Reticulum Stress and Inflammation Induced by Homocysteine in Apolipoprotein E-Deficient Mice

    PubMed Central

    Zhang, Jin-Sheng; Hou, Yue-Long; Lu, Wei-Wei; Ni, Xian-Qiang; Lin, Fan; Yu, Yan-Rong; Tang, Chao-Shu

    2016-01-01

    Aim: Endoplasmic reticulum stress (ERS) and inflammation participate in cardiac fibrosis. Importantly, a novel paracrine/autocrine peptide intermedin1–53 (IMD1–53) in the heart inhibits myocardial fibrosis in rats. However, the mechanisms are yet to be fully elucidated. Methods: Myocardial fibrosis in apolipoprotein E-deficient (ApoE -/-) mice and neonatal rat cardiac fibroblasts (CFs) were induced using homocysteine (Hcy). Results: IMD1–53 inhibited myocardial fibrosis in vivo and in vitro. Picrosirius red staining showed that IMD1–53 reduced myocardial interstitial collagen deposition in ApoE-/- mice treated with Hcy and decreased the expression of myocardial collagen I and III, which was further verified in rat CFs. IMD1–53 attenuated myocardial hypertrophy, as shown by cardiomyocyte cross-sectional area, ratio of heart weight to body weight, and mRNA levels of atrial natriuretic peptide and brain natriuretic peptide. IMD1–53 inhibited the upregulation of ERS hallmarkers such as glucose-regulated protein 78 (GRP78), GRP94, activating transcription factor 6 (ATF6), ATF4, inositol-requiring enzyme 1α, spliced-X-box-binding protein-1, protein kinase receptor-like ER kinase, and eukaryotic translation initiation factor 2α in mouse myocardium and rat CFs treated with Hcy. In addition, IMD1–53 decreased the production of inflammatory factors such as tumor necrosis factor-α, monocyte chemotactic protein-1, interleukin-6 (IL-6), and IL-1β in the mouse myocardium and rat CFs treated with Hcy. Concurrently, IMD1–53 ameliorated the expression of nuclear factor-κB, transforming growth factor-β1, and c-Jun N-terminal kinase in the mouse myocardium and rat CFs treated with Hcy. Conclusions: IMD potentially protects against myocardial fibrosis induced by Hcy in ApoE-/- mice, possibly via attenuating myocardial ERS and inflammation. PMID:27052784

  13. [Anti-β2GPI antibody promotes release of inflammatory and pro-thrombosis molecules from arteries in apolipoprotein E-deficient mice].

    PubMed

    Zhu, Xiaojie; Zhou, Hong; Wang, Xiaoyan; Cai, Qianqian; He, Chao; Xia, Longfei; Zhang, Guiting; Ouyang, Hang

    2017-03-01

    Objective To investigate the roles of anti-beta 2 glycoprotein I antibodies (anti-β2GPI Ab) in the expressions of atherosclerosis(AS)-related inflammatory factors and pro-thrombosis molecules in apolipoprotein E-deficient (ApoE-/-) mice. Methods ApoE-/- mice were randomly divided into normal saline (NS) group, 100 μg anti-β2GPI Ab group, 100 μg homologous antibody (rabbit-IgG) group and 100 μg β2GPI/anti-β2GPI Ab complex group after silastic collars were placed around their carotid arteries by surgery. All mice were fed a high fat diet and corresponding stimuli were given through intraperitoneal injection at 7-day intervals. Six weeks later, the mice were executed. The blockage of carotid arteries of the operated side was observed by HE staining. The expressions of TLR4, tissue factor (TF) and von Willebrand factor (vWF) were detected by immunohistochemistry. The mRNA levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in aorta were tested by real-time quantitative PCR. Results HE staining showed that the blockage of carotid arteries in antibody group was the most obvious. The immunohistochemistry showed that the expressions of TLR4, TF and vWF in anti-β2GPI Ab group increased remarkably. Furthermore, the mRNA levels of IL-1β and TNF-α in anti-β2GPI Ab group were higher than those in the other groups. Conclusion The anti-β2GPI antibody promotes the formation of atherosclerotic plaques in mice by up-regulating the release of inflammatory cytokines IL-1β, TNF-α and thrombosis-related molecules TF, vWF and TLR4, ultimately enhancing the development of AS.

  14. The Akt-nitric oxide-cGMP pathway contributes to nerve growth factor-mediated neurite outgrowth in apolipoprotein E knockout mice.

    PubMed

    Hashikawa-Hobara, Narumi; Hashikawa, Naoya; Yutani, Chikao; Zamami, Yoshito; Jin, Xin; Takatori, Shingo; Mio, Mitsunobu; Kawasaki, Hiromu

    2011-08-01

    Apolipoprotein E (apo)-deficient [apoE(-/-)] mice have peripheral sensory nerve defects and a reduced and delayed response to noxious thermal stimuli. However, to date, no report has focused on the influence of apoE deficiency on calcitonin gene-related peptide (CGRP)-containing nerve fiber extensions. We have shown that the density of CGRP-containing nerve fibers decreases in mesenteric arteries of apoE(-/-) mice compared with wild-type mice. Here, we investigated whether apoE deficiency is involved in nerve growth factor (NGF)-induced CGRP-containing nerve regeneration using apoE(-/-) mice. NGF-mediated CGRP-like immunoreactivity (LI)-neurite outgrowth in apoE(-/-) cultured dorsal root ganglia (DRG) cells was significantly lower than that in wild-type cultures. However, the level of NGF receptor mRNA in apoE(-/-) DRG cells was similar to that in wild-type mice. To clarify the mechanism of the impaired ability of NGF-mediated neurite outgrowth, we focused on the Akt-nitric oxide (NO)-cGMP pathway. Expression of phosphorylated Akt was significantly reduced in apoE(-/-) DRG. The NO donor, sodium nitroprusside or S-nitroso-N-acetylpenicillamine, did not affect NGF-mediated neurite outgrowth in apoE(-/-) cultured DRG cells. However, 8-bromoguanosine 3',5'-cyclic monophosphate sodium salt n-hydrate, a cGMP analog, induced NGF-mediated nerve facilitation similar to wild-type NGF-mediated neurite outgrowth levels. Furthermore, in apoE(-/-) DRG, soluble guanylate cyclase expression was significantly lower than that in wild-type DRG. These results suggest that in apoE(-/-) mice the Akt-NO-cGMP pathway is impaired, which may be caused by NGF-mediated CGRP-LI-neurite outgrowth defects.

  15. COG1410, an Apolipoprotein E-based Peptide, Improves Cognitive Performance and Reduces Cortical Loss Following Moderate Fluid Percussion Injury in the Rat

    PubMed Central

    Kaufman, Nicholas A.; Beare, Jason E.; Tan, Arlene A.; Vitek, Michael P.; McKenna, Suzanne E.; Hoane, Michael R.

    2010-01-01

    COG1410, a small, novel ApoE-mimetic peptide derived from the receptor binding region of Apolipoprotein E (ApoE), has been classified as anti-inflammatory in nature and improves motor, sensorimotor, and cognitive dysfunction following cortical contusion injury (CCI). In order to further examine COG1410’s preclinical efficacy on cognitive recovery, the present study evaluated COG1410 following moderate fluid percussion injury (FPI). Animals were prepared with a moderate, unilateral FPI over the hippocampus. Following FPI, animals received a regimen of five doses of COG1410 or vehicle at 2 and 4 hrs (1.0 mg/kg, i.v.) followed by additional doses administered 24, 48, and 72 hrs (1.0 mg/kg, i.p.). Prior to injury, animals were trained for four days (4 trials/day) in the Morris water maze (MWM) and then tested for retrograde amnesia on post-FPI day 11 and then on a working memory task on day 18. Testing for motor dysfunction on the tapered balanced beam began on day 2 post-FPI. Administration of this regimen of COG1410 significantly improved retention of memory in the retrograde amnesia test compared to vehicle post-FPI. However, COG1410 did not significantly improve acquisition of working memory in the MWM. Motor dysfunction on the tapered beam post-FPI was improved in the COG1410-treated group compared to vehicle treatment. Cortical lesion analysis revealed that the COG1410-treated animals demonstrated significantly less tissue loss compared to vehicle-treated animals. The results of this study suggest that COG1410 significantly limited the behavioral dysfunction and tissue loss associated with FPI and demonstrated continued preclinical efficacy for TBI. PMID:20600347

  16. Resveratrol protects against diet-induced atherosclerosis by reducing low-density lipoprotein cholesterol and inhibiting inflammation in apolipoprotein E-deficient mice

    PubMed Central

    Chang, Geng-Ruei; Chen, Po-Lin; Hou, Po-Hsun; Mao, Frank Chiahung

    2015-01-01

    Objective(s): Resveratrol (RES) is a polyphenol compound that has been shown a promising cardioprotective effect. However, some reports have yielded conflicting findings. Herein, we investigated the anti-atherosclerotic effects of RES in apolipoprotein E (apo E)-deficient mice on a high cholesterol diet. Materials and Methods: Firstly, atherosclerosis was induced by feeding a high cholesterol diet to apo E-deficient mice. Then, we examined its effects on weight control, and serum interleukin-6 (IL-6) levels and used histopathological methods to analyze morphology and inflammatory marker of atherosclerotic lesions in mice orally supplemented with high (25 mg/kg/day) and low (5 mg/kg/day) doses of RES for 8 weeks. Results: Mice with high dose of RES had reduced epididymal fat pads, and lower serum IL-6 levels compared with those of control mice. Moreover, RES in high doses also decreased the low-density lipoprotein cholesterol (LDL-C) levels and atherogenic index (LDL-C/HDL-C) in the mice. Dissection of high-dose RES-treated mice revealed a marked reduction in fat deposition, percentage of mice with atherosclerotic lesion, and intima/media ratio in the aortic areas. The expressions of macrophage-specific marker F4/80 and cardiovascular inflammatory marker NF-κB in atherosclerotic vessels were both diminished in the atherosclerotic vessels of high-dose RES-supplementated apo E-deficient mice. Conclusion: These results suggest that RES prevented the effects of a high cholesterol diet on the rate of accretion in atherosclerosis progression by reducing the LDL-C levels and suppressing atherosclerotic inflammation. RES can therefore be valuable in the development of new anti-atherosclerotic agents. PMID:26949492

  17. Peritoneal delivery of sodium pyrophosphate blocks the progression of pre-existing vascular calcification in uremic apolipoprotein-E knockout mice.

    PubMed

    de Oliveira, Rodrigo B; Louvet, Loïc; Riser, Bruce L; Barreto, Fellype C; Benchitrit, Joyce; Rezg, Raja; Poirot, Sabrina; Jorgetti, Vanda; Drüeke, Tilman B; Massy, Ziad A

    2015-08-01

    Chronic kidney disease (CKD) is generally associated with disturbances of mineral and bone metabolism. They contribute to the development of vascular calcification (VC), a strong, independent predictor of cardiovascular risk. Pyrophosphate (PPi), an endogenous inhibitor of hydroxyapatite formation, has been shown to slow the progression of VC in uremic animals. Since in patients with CKD treatment is usually initiated for already existing calcifications, we aimed to compare the efficacy of PPi therapy with that of the phosphate binder sevelamer, using a uremic apolipoprotein-E knockout mouse model with advanced VCs. After CKD creation or sham surgery, 12-week-old female mice were randomized to one sham group and four CKD groups (n = 18-19/group). Treatment was initiated 8 weeks after left nephrectomy allowing prior VC development. Uremic groups received either intraperitoneal PPi (high dose, 1.65 mg/kg or low dose, 0.33 mg/kg per day), oral sevelamer (3 % in diet), or placebo treatment for 8 weeks. Both intima and media calcifications worsened with time in placebo-treated CKD mice, based on both quantitative image analysis and biochemical measurements. Progression of calcification between 8 and 16 weeks was entirely halted by PPi treatment, as it was by sevelamer treatment. PPi did not induce consistent bone histomorphometry changes. Finally, the beneficial vascular action of PPi probably involved mechanisms different from that of sevelamer. Further studies are needed to gain more precise insight into underlying mechanisms and to see whether PPi administration may also be useful in patients with CKD and VC.

  18. Effects of pyrophosphate delivery in a peritoneal dialysis solution on bone tissue of apolipoprotein-E knockout mice with chronic kidney disease.

    PubMed

    Barreto, Fellype C; de Oliveira, Rodrigo B; Benchitrit, Joyce; Louvet, Loïc; Rezg, Raja; Poirot, Sabrina; Jorgetti, Vanda; Drüeke, Tilman B; Riser, Bruce L; Massy, Ziad A

    2014-11-01

    Vascular calcification (VC) is a risk factor for cardiovascular mortality in the setting of chronic kidney disease (CKD). Pyrophosphate (PPi), an endogenous molecule that inhibits hydroxyapatite crystal formation, has been shown to prevent the development of VC in animal models of CKD. However, the possibility of harmful effects of exogenous administration of PPi on bone requires further investigation. To this end, we examined by histomorphometry the bone of CKD mice after intraperitoneal PPi administration. After CKD creation or sham surgery, 10-week-old female apolipoprotein-E knockout (apoE(-/-)) mice were randomized to one non-CKD group or 4 CKD groups (n = 10-35/group) treated with placebo or three distinct doses of PPi, and fed with standard diet. Eight weeks later, the animals were killed. Serum and femurs were sampled. Femurs were processed for bone histomorphometry. Placebo-treated CKD mice had significantly higher values of osteoid volume, osteoid surface and bone formation rate than sham-placebo mice with normal renal function. Slightly higher osteoid values were observed in CKD mice in response to very low PPi dose (OV/BV, O.Th and ObS/BS) and, for one parameter measured, to high PPi dose (O.Th), compared to placebo-treated CKD mice. Treatment with PPi did not modify any other structural parameters. Mineral apposition rates, and other parameters of bone formation and resorption were not significantly different among the treated animal groups or control CKD placebo group. In conclusion, PPi does not appear to be deleterious to bone tissue in apoE(-/-) mice with CKD, although a possible stimulatory PPi effect on osteoid formation may be worth further investigation.

  19. Identification of a non-canonical E-box motif as a regulatory element in the proximal promoter region of the apolipoprotein E gene.

    PubMed Central

    Salero, Enrique; Giménez, Cecilio; Zafra, Francisco

    2003-01-01

    We have used the yeast one-hybrid system to identify transcription factors with binding capability to specific sequences in proximal regions of the apolipoprotein E gene ( APOE ) promoter. The sequence between -113 and -80 nt, which contains regulatory elements in various cell types, was used as a bait to screen a human brain cDNA library. Four cDNA clones that encoded portions of the human upstream-stimulatory-factor (USF) transcription factor were isolated. Electrophoretic-mobility-shift assays ('EMSAs') using nuclear extracts from various human cell lines as well as from rat brain and liver revealed the formation of two DNA-protein complexes within the sequence CACCTCGTGAC (region -101/-91 of the APOE promoter) that show similarity to the E-box element. The retarded complexes contained USF1, as deduced from competition and supershift assays. Functional experiments using different APOE promoter-luciferase reporter constructs transiently transfected into U87, HepG2 or HeLa cell lines showed that mutations that precluded the formation of complexes decreased the basal activity of the promoter by about 50%. Overexpression of USF1 in U87 glioblastoma cells led to an increased activity of the promoter that was partially mediated by the atypical E-box. The stimulatory effect of USF1 was cell-type specific, as it was not observed in hepatoma HepG2 cells. Similarly, overexpression of a USF1 dominant-negative mutant decreased the basal activity of the promoter in glioblastoma, but not in hepatoma, cells. These data indicated that USF, and probably other related transcription factors, might be involved in the basal transcriptional machinery of APOE by binding to a non-canonical E-box motif within the proximal promoter. PMID:12444925

  20. Long-Term Effects of {sup 56}Fe Irradiation on Spatial Memory of Mice: Role of Sex and Apolipoprotein E Isoform

    SciTech Connect

    Villasana, Laura E.; Benice, Theodore S.; Raber, Jacob

    2011-06-01

    Purpose: To assess whether the effects of cranial {sup 56}Fe irradiation on the spatial memory of mice in the water maze are sex and apolipoprotein E (apoE) isoform dependent and whether radiation-induced changes in spatial memory are associated with changes in the dendritic marker microtubule-associated protein 2 (MAP-2) and the presynaptic marker synaptophysin. Methods and Materials: Two-month-old male and female mice expressing human apoE3 or apoE4 received either a 3-Gy dose of cranial {sup 56}Fe irradiation (600 MeV/amu) or sham irradiation. Mice were tested in a water maze task 13 months later to assess effects of irradiation on spatial memory retention. After behavioral testing, the brain tissues of these mice were analyzed for synaptophysin and MAP-2 immunoreactivity. Results: After irradiation, spatial memory retention of apoE3 female, but not male, mice was impaired. A general genotype deficit in spatial memory was observed in sham-irradiated apoE4 mice. Strikingly, irradiation prevented this genotype deficit in apoE4 male mice. A similar but nonsignificant trend was observed in apoE4 female mice. Although there was no change in MAP-2 immunoreactivity after irradiation, synaptophysin immunoreactivity was increased in irradiated female mice, independent of genotype. Conclusions: The effects of {sup 56}Fe irradiation on the spatial memory retention of mice are critically influenced by sex, and the direction of these effects is influenced by apoE isoform. Although in female mice synaptophysin immunoreactivity provides a sensitive marker for effects of irradiation, it cannot explain the apoE genotype-dependent effects of irradiation on the spatial memory retention of the mice.

  1. Equol Attenuates Atherosclerosis in Apolipoprotein E-Deficient Mice by Inhibiting Endoplasmic Reticulum Stress via Activation of Nrf2 in Endothelial Cells

    PubMed Central

    Shi, Linying; Qin, Li; Zhang, Qianyong; Mi, Mantian

    2016-01-01

    The development of atherosclerosis is closely related to excessive endoplasmic reticulum stress (ERs). Equol reportedly protects against cardiovascular disease; however, the underlying mechanism for this protection remains unknown. Herein, the mechanisms contributing to the atheroprotective effect of equol were addressed using apolipoprotein E knockout (apoE-/-) mice fed a high-fat diet (HFD) with or without equol. Equol intervention reduced atherosclerotic lesions in the aorta in HFD-fed apoE-/- mice. Plasma lipid analysis showed that equol intervention reduced triglycerides, total cholesterol and LDL-cholesterol and increased HDL-cholesterol. Additionally, equol administration decreased lipid accumulation in the liver. Simultaneously, equol treatment inhibited cell apoptosis induced by t-BHP and thapsigargin in human umbilical vein endothelial cells (HUVECs). Furthermore, equol treatment attenuated palmitate, t-BHP or thapsigargin-induced upregulation of ER stress markers, including p-PERK, p-eIF2α, GRP78, ATF6 and CHOP proteins expression. The same tendency was also observed in aortic lysates in apoE-/- mice fed with equol plus HFD compared with HFD alone. Moreover, equol treatment dose dependently activated the Nrf2 signaling pathway under oxidative stress. Additionally, elevation of Nrf2 induction was found in aortic lysates in apoE-/- mice fed with a HFD diet containing equol compared with a HFD diet without equol. Importantly, Nrf2 siRNA interference induced CHOP and attenuated the effect of equol to inhibit t-BHP mediated CHOP induction, furthermore, abrogated cell apoptosis induced by t-BHP, suggesting a role for Nrf2 in the protective effect of equol in HUVECs. Collectively, these findings implicate that the improvement of atherosclerosis by equol through attenuation of ER stress is mediated, at least in part, by activating the Nrf2 signaling pathway. PMID:27907038

  2. Inhibition of c-Jun N-terminal kinase attenuates low shear stress-induced atherogenesis in apolipoprotein E-deficient mice.

    PubMed

    Wang, Juan; An, Feng Shuang; Zhang, Wei; Gong, Lei; Wei, Shu Jian; Qin, Wei Dong; Wang, Xu Ping; Zhao, Yu Xia; Zhang, Yun; Zhang, Cheng; Zhang, Ming-Xiang

    2011-01-01

    Atherosclerosis begins as local inflammation of arterial walls at sites of disturbed flow, such as vessel curvatures and bifurcations with low shear stress. c-Jun NH₂-terminal kinase (JNK) is a major regulator of flow-dependent gene expression in endothelial cells in atherosclerosis. However, little is known about the in vivo role of JNK in low shear stress in atherosclerosis. We aimed to observe the effect of JNK on low shear stress-induced atherogenesis in apolipoprotein E-deficient (ApoE(-/-)) mice and investigate the potential mechanism in human umbilical vein endothelial cells (HUVECs). We divided 84 male ApoE(-/-) mice into two groups for treatment with normal saline (NS) (n = 42) and JNK inhibitor SP600125 (JNK-I) (n = 42). Perivascular shear stress modifiers were placed around the right carotid arteries, and plaque formation was studied at low shear stress regions. The left carotid arteries without modifiers represented undisturbed shear stress as a control. The NS group showed atherosclerotic lesions in arterial regions with low shear stress, whereas the JNK-I group showed almost no atherosclerotic lesions. Corresponding to the expression of proatherogenic vascular cell adhesion molecule 1 (VCAM-1), phospho-JNK (p-JNK) level was higher in low shear stress regions with NS than with JNK-I inhibitor. In HUVECs under low shear stress, siRNA knockdown and SP600125 inhibition of JNK attenuated nuclear factor (NF)-κB activity and VCAM-1 expression. Furthermore, siRNA knockdown of platelet endothelial cell adhesion molecule 1 (PECAM-1) (CD31) reduced p-JNK and VCAM-1 levels after low shear stress stimulation. JNK may play a critical role in low shear stress-induced atherogenesis by a PECAM-1-dependent mechanosensory pathway and modulating NF-κB activity and VCAM-1 expression.

  3. Long-term post-operative cognitive decline in the elderly: the effects of anesthesia type, apolipoprotein E genotype, and clinical antecedents

    PubMed Central

    Ancelin, Marie-Laure; De Roquefeuil, Guilhem; Scali, Jacqueline; Bonnel, François; Adam, Jean-François; Cheminal, Jean-Claude; Cristol, Jean-Paul; Dupuy, Anne-Marie; Carrière, Isabelle; Ritchie, Karen

    2010-01-01

    Cognitive dysfunction in the elderly commonly observed following anesthesia has been attributed to age-related neuronal changes exacerbated by pharmacotoxic effects. However, the extent to which these changes may persist following recovery from surgery is still largely unknown. This study investigates the long-term effects of anesthesia on cognitive functioning after orthopedic surgery in 270 elderly patients over the age of 65 who completed a computerized cognitive battery before and 8 days, 4 and 13 months after surgery. Their performance was compared to that of 310 elderly controls who completed the same neuro-psychiatric evaluation at baseline and one-year interval. Multivariate analyses adjusted for socio-demographic variables, depressive symptomatology, vascular pathology as well as baseline cognitive performance. We found early and transient post-operative decline in reaction time and constructional praxis. With regard to long-term changes we observed improvement compared to controls in most verbal tasks (probably due to learning effects). On the other hand, a clear dissociation effect was observed for several areas of visuospatial functioning which persisted up to the 13-month follow-up. This specific pattern of visuospatial deficit was found to be independent of apolipoprotein E genotype and closely resembles what has recently been termed vascular mild cognitive impairment, in turn associated with subtle sub-cortical vascular changes. The observation of only minor differences between persons operated by general and regional anesthesia makes it difficult to attribute these changes directly to the anesthetic agents themselves, suggesting that cognitive dysfunction may be attributable at least in part to peri-operative conditions, notably stress and glucocorticoid exposure. PMID:20858969

  4. RNA Dimerization Promotes PKR Dimerization and Activation

    PubMed Central

    Heinicke, Laurie A.; Wong, C. Jason; Lary, Jeffrey; Nallagatla, Subba Rao; Diegelman-Parente, Amy; Zheng, Xiaofeng; Cole, James L.; Bevilacqua, Philip C.

    2009-01-01

    The double-stranded RNA (dsRNA)-activated protein kinase (PKR) plays a major role in the innate immune response in humans. PKR binds dsRNA non-sequence specifically and requires a minimum of 15 bp dsRNA for one protein to bind and 30 bp dsRNA to induce protein dimerization and activation by autophosphorylation. PKR phosphorylates eIF2α, a translation initiation factor, resulting in the inhibition of protein synthesis. We investigated the mechanism of PKR activation by an RNA hairpin with a number of base pairs intermediate between these 15 to 30 bp limits: HIV-I TAR RNA, a 23 bp hairpin with three bulges that is known to dimerize. To test whether RNA dimerization affects PKR dimerization and activation, TAR monomers and dimers were isolated from native gels and assayed for RNA and protein dimerization. To modulate the extent of dimerization, we included TAR mutants with different secondary features. Native gel mixing experiments and analytical ultracentrifugation indicate that TAR monomers bind one PKR monomer and that TAR dimers bind two or three PKRs, demonstrating that RNA dimerization drives the binding of multiple PKR molecules. Consistent with functional dimerization of PKR, TAR dimers activated PKR while TAR monomers did not, and RNA dimers with fewer asymmetrical secondary structure defects, as determined by enzymatic structure mapping, were more potent activators. Thus, the secondary structure defects in the TAR RNA stem function as antideterminants to PKR binding and activation. Our studies support that dimerization of a 15–30 bp hairpin RNA, which effectively doubles its length, is a key step in driving activation of PKR and provide a model for how RNA folding can be related to human disease. PMID:19445956

  5. Association of the apolipoprotein E {epsilon}4 allele with clinical subtypes of autopsy-confirmed Alzheimer`s Disease

    SciTech Connect

    Zubenko, G.S.; Stiffler, S.; Kopp, U.

    1994-09-15

    Consistent with previous reports, we observed a significant association of the APOE {epsilon}4 allele with Alzheimer`s Disease (AD) in a series of 91 autopsy-confirmed cases. The {epsilon}4 allele frequency was higher in cases with a family history of AD-like dementia (0.54 {+-} 0.07), although the {epsilon}4 allele frequency in the AD cases with a negative family history (0.38 {+-} 0.05) remained significantly greater than that for the non-AD control group (0.13 {+-} 0.03). A similar increase in {epsilon}4 allele frequency (0.54 {+-} 0.07) was observed in the AD cases with amyloid angiopathy, compared to those who did not have amyloid angiopathy (0.35 {+-} 0.04). Contrary to previous reports, no effect of the dosage of the {epsilon}4 allele was found on the age of onset of dementia among the AD cases and, contrary to reports suggesting an association of {epsilon}4 and atherosclerosis, the {epsilon}4 allele frequency was similar in cases with or without concurrent brain infarcts. Modest but consistent correlations were observed between the dosage of {epsilon}4 alleles and the cortical density of senile plaques, but not neurofibrillary tangles. The last finding suggests that the pathogenic events mediated by the {epsilon}4 allele may be more directly involved in the formation of senile plaques, the identifying lesions in AD, than neurofibrillary tangles. A robust association of both the presence of an {epsilon}4 allele and a family history of AD-like dementia with concurrent amyloid angiopathy occurred within our sample of AD cases. This association arose from an interaction of the {epsilon}4 allele with a separate familial factor for which a family history of dementia served as a surrogate. These results suggest that amyloid angiopathy may be a common or central feature of a form of familial AD that is associated with the transmission of the APOE {epsilon}4 allele. 22 refs., 2 figs., 5 tabs.

  6. Structural insights into the IgE mediated responses induced by the allergens Hev b 8 and Zea m 12 in their dimeric forms

    PubMed Central

    Mares-Mejía, Israel; Martínez-Caballero, Siseth; Garay-Canales, Claudia; Cano-Sánchez, Patricia; Torres-Larios, Alfredo; Lara-González, Samuel; Ortega, Enrique; Rodríguez-Romero, Adela

    2016-01-01

    Oligomerization of allergens plays an important role in IgE-mediated reactions, as effective crosslinking of IgE- FcεRI complexes on the cell membrane is dependent on the number of exposed B-cell epitopes in a single allergen molecule or on the occurrence of identical epitopes in a symmetrical arrangement. Few studies have attempted to experimentally demonstrate the connection between allergen dimerization and the ability to trigger allergic reactions. Here we studied plant allergenic profilins rHev b 8 (rubber tree) and rZea m 12 (maize) because they represent an important example of cross-reactivity in the latex-pollen-food syndrome. Both allergens in their monomeric and dimeric states were isolated and characterized by exclusion chromatography and mass spectrometry and were used in immunological in vitro experiments. Their crystal structures were solved, and for Hev b 8 a disulfide-linked homodimer was found. Comparing the structures we established that the longest loop is relevant for recognition by IgE antibodies, whereas the conserved regions are important for cross-reactivity. We produced a novel monoclonal murine IgE (mAb 2F5), specific for rHev b 8, which was useful to provide evidence that profilin dimerization considerably increases the IgE-mediated degranulation in rat basophilic leukemia cells. PMID:27586352

  7. Dimer crystallization of chiral proteoids.

    PubMed

    Wang, Po-Yuan; Mason, Thomas G

    2017-03-08

    Proteins can self-assemble into a variety of exquisitely organized structures through hierarchical reaction pathways. To examine how different core shapes of proteins and entropy combine to influence self-assembly, we create systems of lithographically fabricated proteomimetic colloids, or 'proteoids', and explore how Brownian monolayers of mobile proteoids, which have hard interactions, self-assemble as they are slowly crowded. Remarkably, chiral C-shaped proteoids having circular heads on only one side form enantiopure lock-and-key chiral dimers; these dimers have corrugated, shape-complementary perimeters, so they, in turn, form lock-and-key arrangements into chiral dimer crystals. Time-lapse video microscopy reveals the expulsion of monomers from the growing dimer crystals through tautomerization translocation reactions which expedite the crystallization kinetics. By lithographically mutating proteoids, we also tune the types and structures of the resulting dimer crystals. Thus, rational design of sub-particle features in hard-core colloidal shapes can be used to sterically select desired self-assembly pathways without introducing any site-specific attractions, thereby generating a striking degree of hierarchical self-ordering, reminiscent of protein crystallization.

  8. Apolipoprotein E enhances hepatic lipase-mediated hydrolysis of reconstituted high-density lipoprotein phospholipid and triacylglycerol in an isoform-dependent manner.

    PubMed

    Hime, Neil J; Drew, Kate J; Hahn, Chris; Barter, Philip J; Rye, Kerry-Anne

    2004-09-28

    This study compares the kinetics of hepatic lipase (HL)-mediated phospholipid and triacylglycerol hydrolysis in spherical, reconstituted high-density lipoproteins (rHDL) that contain either apolipoprotein E2 (apoE2), apoE3, apoE4, or apoA-I as the sole apolipoprotein. HL-mediated phospholipid hydrolysis was assessed by incubating various concentrations of rHDL that contained only cholesteryl esters (CE) in their core, (E2/CE)rHDL, (E3/CE)rHDL, (E4/CE)rHDL, and (A-I/CE)rHDL, with a constant amount of HL. The rate of phospholipid hydrolysis was determined as the formation of nonesterified fatty acid mass. HL-mediated triacylglycerol hydrolysis was assessed in rHDL containing CE, unlabeled triacylglycerol, and [(3)H]triacylglycerol in their core, (E2/TG)rHDL, (E3/TG)rHDL, (E4/TG)rHDL, and (A-I/TG)rHDL. Triacylglycerol hydrolysis was determined as the ratio of (3)H-labeled hydrolysis products to (3)H-labeled unhydrolyzed triacylglycerol. The rates of phospholipid hydrolysis in the (E2/CE)rHDL, (E3/CE)rHDL, and (E4/CE)rHDL were significantly greater than that in the (A-I/CE)rHDL. The rates of triacylglycerol hydrolysis were also greater in the (E2/TG)rHDL, (E3/TG)rHDL, and (E4/TG)rHDL compared to the (A-I/TG)rHDL, although to a lesser degree than observed with phospholipid hydrolysis. Furthermore, the rates of both phospholipid and triacylglycerol hydrolyses were greater in the (E2)rHDL than in either the (E3)rHDL or the (E4)rHDL. These results show that apoE increases the rate of HL-mediated phospholipid and triacylglycerol hydrolysis in rHDL and that this influence is isoform dependent.

  9. High cholesterol diet results in increased expression of interleukin-6 and caspase-1 in the brain of apolipoprotein E knockout and wild type mice.

    PubMed

    Rahman, S M A; Van Dam, A-M; Schultzberg, M; Crisby, M

    2005-12-01

    Inflammation in the central nervous system is an early hallmark of many neurodegenerative diseases including Alzheimer's disease (AD). Recently, increasing evidence suggests that hypercholesterolemia during midlife and abnormalities in the cholesterol metabolism could have an important role in the pathogenesis of AD. In the present study, we have evaluated the effect of high cholesterol (HC) diet on the expression of interleukin-6 (IL-6), a cytokine involved in neurodegeneration, and caspase-1, that is responsible for the cleavage of the precursors of interleukin-1 beta (IL-1 beta) and interleukin-18 (IL-18) in the brain of apolipoprotein E (Apo E) knock-out (KO) and wild type (WT) mice. The density of IL-6-positive cells was increased in the hippocampus (p<0.0001) and the dorsal part of the cortex (p<0.001) of KO and WT mice on HC diet (KOHC and WTHC mice, respectively) compared to KO and WT mice on ND (KOND and WTND mice, respectively). KOHC mice had increased caspase-1 positive cells and staining intensity in the hippocampus in comparison with WTHC mice (p<0.01). In the hippocampus, the density of caspase-1 positive cells was also higher in KOHC compared to KOND mice (p<0.05) and KOHC compared with WTHC mice (p<0.01). There was a major increase in caspase-1 immunoreactivity and cell density in both the dosal part of the cortex (p<0.001) and the lateral part of the cortex (p<0.005) in KO and WT mice on HC diet compared to ND. The findings of the present study indicate that chronic exposure to HC diet increases the expression of the two important inflammatory mediators IL-6 and caspase-1 in the brain of KO and WT mice. In the case of caspase-1, we report a major difference in the effect of HC diet on the KO mice compared to WT mice in the hippocampus. Increased expression of inflammatory mediators involved in neurodegeneration could be a potential mechanism by which hypercholesterolemia and HC diet increase the risk of AD.

  10. Role of Rydberg states in the photostability of heterocyclic dimers: the case of pyrazole dimer.

    PubMed

    Zilberg, Shmuel; Haas, Yehuda

    2012-11-26

    A new route for the nonradiative decay of photoexcited, H-bonded, nitrogen-containing, heterocyclic dimers is offered and exemplified by a study of the pyrazole dimer. In some of these systems the N(3s) Rydberg state is the lowest excited singlet state. This state is formed by direct light absorption or by nonradiative transition from the allowed ππ* state. An isomer of this Rydberg state is formed by H atom transfer to the other component of the dimer. The newly formed H-bonded radical pair is composed of two radicals (a H-adduct of pyrazole, a heterocyclic analogue of the NH(4) radical) and the pyrazolium π-radical. It is calculated to have a shallow local minimum and is the lowest point on the PES of the H-pyrazole/pyrazolium radical pair. This species can cross back to the ground state of the original dimer through a relatively small energy gap and compete with the H-atom loss channel, known for the monomer. In both Rydberg dimers, an electron occupies a Rydberg orbital centered mostly on one of the two components of the dimer. This Rydberg Center Shift (RCS) mechanism, proposed earlier (Zilberg, S.; Kahan, A.; Haas, Y. Phys. Chem. Chem. Phys. 2012, 14, 8836), leads to deactivation of the electronically excited dimer while keeping it intact. It, thus, may explain the high photostability of the pyrazole dimer as well as other heterocyclic dimers.

  11. Age-related cognitive decline and associations with sex, education and apolipoprotein E genotype across ethnocultural groups and geographic regions: a collaborative cohort study

    PubMed Central

    Lipnicki, Darren M.; Crawford, John D.; Thalamuthu, Anbupalam; Castro-Costa, Erico; Stephan, Blossom C. M.; Lipton, Richard B.; Katz, Mindy J.; Ritchie, Karen; Scali, Jacqueline; Ancelin, Marie-Laure; Scarmeas, Nikolaos; Yannakoulia, Mary; Dardiotis, Efthimios; Lam, Linda C. W.; Fung, Ada W. T.; Vaccaro, Roberta; Davin, Annalisa; Kim, Ki Woong; Han, Ji Won; Kim, Tae Hui; Cherbuin, Nicolas; Butterworth, Peter; Scazufca, Marcia; Kumagai, Shuzo; Chen, Sanmei; Narazaki, Kenji; Lobo, Antonio; Lopez-Anton, Raúl; Santabárbara, Javier; Sachdev, Perminder S.

    2017-01-01

    Background The prevalence of dementia varies around the world, potentially contributed to by international differences in rates of age-related cognitive decline. Our primary goal was to investigate how rates of age-related decline in cognitive test performance varied among international cohort studies of cognitive aging. We also determined the extent to which sex, educational attainment, and apolipoprotein E ε4 allele (APOE*4) carrier status were associated with decline. Methods and findings We harmonized longitudinal data for 14 cohorts from 12 countries (Australia, Brazil, France, Greece, Hong Kong, Italy, Japan, Singapore, Spain, South Korea, United Kingdom, United States), for a total of 42,170 individuals aged 54–105 y (42% male), including 3.3% with dementia at baseline. The studies began between 1989 and 2011, with all but three ongoing, and each had 2–16 assessment waves (median = 3) and a follow-up duration of 2–15 y. We analyzed standardized Mini-Mental State Examination (MMSE) and memory, processing speed, language, and executive functioning test scores using linear mixed models, adjusted for sex and education, and meta-analytic techniques. Performance on all cognitive measures declined with age, with the most rapid rate of change pooled across cohorts a moderate -0.26 standard deviations per decade (SD/decade) (95% confidence interval [CI] [-0.35, -0.16], p < 0.001) for processing speed. Rates of decline accelerated slightly with age, with executive functioning showing the largest additional rate of decline with every further decade of age (-0.07 SD/decade, 95% CI [-0.10, -0.03], p = 0.002). There was a considerable degree of heterogeneity in the associations across cohorts, including a slightly faster decline (p = 0.021) on the MMSE for Asians (-0.20 SD/decade, 95% CI [-0.28, -0.12], p < 0.001) than for whites (-0.09 SD/decade, 95% CI [-0.16, -0.02], p = 0.009). Males declined on the MMSE at a slightly slower rate than females (difference = 0

  12. Proteomic Analysis of Mitochondria-Enriched Fraction Isolated from the Frontal Cortex and Hippocampus of Apolipoprotein E Knockout Mice Treated with Alda-1, an Activator of Mitochondrial Aldehyde Dehydrogenase (ALDH2)

    PubMed Central

    Stachowicz, Aneta; Olszanecki, Rafał; Suski, Maciej; Głombik, Katarzyna; Basta-Kaim, Agnieszka; Adamek, Dariusz; Korbut, Ryszard

    2017-01-01

    The role of different genotypes of apolipoprotein E (apoE) in the etiology of Alzheimer’s disease is widely recognized. It has been shown that altered functioning of apoE may promote 4-hydroxynonenal modification of mitochondrial proteins, which may result in mitochondrial dysfunction, aggravation of oxidative stress, and neurodegeneration. Mitochondrial aldehyde dehydrogenase (ALDH2) is an enzyme considered to perform protective function in mitochondria by the detoxification of the end products of lipid peroxidation, such as 4-hydroxynonenal and other reactive aldehydes. The goal of our study was to apply a differential proteomics approach in concert with molecular and morphological techniques to elucidate the changes in the frontal cortex and hippocampus of apolipoprotein E knockout (apoE−/−) mice upon treatment with Alda-1—a small molecular weight activator of ALDH2. Despite the lack of significant morphological changes in the brain of apoE−/− mice as compared to age-matched wild type animals, the proteomic and molecular approach revealed many changes in the expression of genes and proteins, indicating the impairment of energy metabolism, neuroplasticity, and neurogenesis in brains of apoE−/− mice. Importantly, prolonged treatment of apoE−/− mice with Alda-1 led to the beneficial changes in the expression of genes and proteins related to neuroplasticity and mitochondrial function. The pattern of alterations implies mitoprotective action of Alda-1, however, the accurate functional consequences of the revealed changes require further research. PMID:28218653

  13. Membrane-associated Ras dimers are isoform-specific: K-Ras dimers differ from H-Ras dimers.

    PubMed

    Jang, Hyunbum; Muratcioglu, Serena; Gursoy, Attila; Keskin, Ozlem; Nussinov, Ruth

    2016-06-15

    Are the dimer structures of active Ras isoforms similar? This question is significant since Ras can activate its effectors as a monomer; however, as a dimer, it promotes Raf's activation and MAPK (mitogen-activated protein kinase) cell signalling. In the present study, we model possible catalytic domain dimer interfaces of membrane-anchored GTP-bound K-Ras4B and H-Ras, and compare their conformations. The active helical dimers formed by the allosteric lobe are isoform-specific: K-Ras4B-GTP favours the α3 and α4 interface; H-Ras-GTP favours α4 and α5. Both isoforms also populate a stable β-sheet dimer interface formed by the effector lobe; a less stable β-sandwich interface is sustained by salt bridges of the β-sheet side chains. Raf's high-affinity β-sheet interaction is promoted by the active helical interface. Collectively, Ras isoforms' dimer conformations are not uniform; instead, the isoform-specific dimers reflect the favoured interactions of the HVRs (hypervariable regions) with cell membrane microdomains, biasing the effector-binding site orientations, thus isoform binding selectivity.

  14. Dimer monomer transition and dimer re-formation play important role for ATM cellular function during DNA repair.

    PubMed

    Du, Fengxia; Zhang, Minjie; Li, Xiaohua; Yang, Caiyun; Meng, Hao; Wang, Dong; Chang, Shuang; Xu, Ye; Price, Brendan; Sun, Yingli

    2014-10-03

    The ATM protein kinase, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks, mediates responses to ionizing radiation in mammalian cells. Here we show that ATM is held inactive in unirradiated cells as a dimer and phosphorylates the opposite strand of the dimer in response to DNA damage. Cellular irradiation induces rapid intermolecular autophosphorylation of serine 1981 that causes dimer dissociation and initiates cellular ATM kinase activity. ATM cannot phosphorylate the substrates when it could not undergo dimer monomer transition. After DNA repair, the active monomer will undergo dephosphorylation to form dimer again and dephosphorylation is critical for dimer re-formation. Our work reveals novel function of ATM dimer monomer transition and explains why ATM dimer monomer transition plays such important role for ATM cellular activity during DNA repair.

  15. Influence of Aqueous-Salt Conditions on the Structure and Dynamics of the Monomeric and Novel Dimeric forms of the Alzheimer s ABeta21-30 protein fragment

    NASA Astrophysics Data System (ADS)

    Smith, Micholas Dean

    The behavior of the Alzheimer's related peptide Abeta is the subject of much study. In typical computational studies the environment local to the peptide is assumed to be pure water; however, in vivo the peptide is found in the extracellular space near the plasma membrane which is rich in ionic species. In this thesis, the hypothesis that the presence of group I/IIA salts will result in increased sampling of disordered structures as well as modify the dynamics of meta-stable structural motifs in the small folding nucleus of the Abeta peptide (Abeta21-30) is examined under a variety of ionic environments and was shown that of the tested salts, CaCl2 (and MgCl2, to a much lesser degree) did increase the propensity for disordered states; while, the group IA salts, KCl and NaCl, had little effect on the secondary structure of the peptide. Further, study of three familial mutations of this peptide region is also performed under aqueous salt-environments to elucidate further mechanistic details of how aqueous salts modify the region's behavior. Finally, as experimental results have highlighted that aggregation rates of the full-length peptide are modified by the presence of CaCl2, this work examines novel dimers states of Abeta21-30 and their stabilities when exposed to CaCl2.

  16. Additive effect of LRP8/APOER2 R952Q variant to APOE ε2/ε3/ε4 genotype in modulating apolipoprotein E concentration and the risk of myocardial infarction: a case-control study

    PubMed Central

    Martinelli, Nicola; Olivieri, Oliviero; Shen, Gong-Qing; Trabetti, Elisabetta; Pizzolo, Francesca; Busti, Fabiana; Friso, Simonetta; Bassi, Antonella; Li, Lin; Hu, Ying; Pignatti, Pier Franco; Corrocher, Roberto; Wang, Qing Kenneth; Girelli, Domenico

    2009-01-01

    Background The R952Q variant in the low density lipoprotein receptor-related protein 8 (LRP8)/apolipoprotein E receptor 2 (ApoER2) gene has been recently associated with familial and premature myocardial infarction (MI) by means of genome-wide linkage scan/association studies. We were interested in the possible interaction of the R952Q variant with another established cardiovascular genetic risk factor belonging to the same pathway, namely apolipoprotein E (APOE) ε2/ε3/ε4 genotype, in modulating apolipoprotein E (ApoE) plasma levels and risk of MI. Methods In the Italian cohort used to confirm the association of the R952Q variant with MI, we assessed lipid profile, apolipoprotein concentrations, and APOE ε2/ε3/ε4 genotype. Complete data were available for a total of 681 subjects in a case-control setting (287 controls and 394 patients with MI). Results Plasma ApoE levels decreased progressively across R952Q genotypes (mean levels ± SD = RR: 0.045 ± 0.020, RQ: 0.044 ± 0.014, QQ: 0.040 ± 0.008 g/l; P for trend = 0.047). Combination with APOE genotypes revealed an additive effect on ApoE levels, with the highest level observed in RR/non-carriers of the E4 allele (0.046 ± 0.021 g/l), and the lowest level in QQ/E4 carriers (0.035 ± 0.009 g/l; P for trend = 0.010). QQ/E4 was also the combined genotype with the most significant association with MI (OR 3.88 with 95%CI 1.08–13.9 as compared with RR/non-carriers E4). Conclusion Our data suggest that LRP8 R952Q variant may have an additive effect to APOE ε2/ε3/ε4 genotype in determining ApoE concentrations and risk of MI in an Italian population. PMID:19439088

  17. Photochemical dimerization of organic compounds

    DOEpatents

    Crabtree, Robert H.; Brown, Stephen H.; Muedas, Cesar A.; Ferguson, Richard R.

    1992-01-01

    At least one of selectivity and reaction rate of photosensitized vapor phase dimerizations, including dehydrodimerizations, hydrodimerizations and cross-dimerizations of saturated and unsaturated organic compounds is improved by conducting the dimerization in the presence of hydrogen or nitrous oxide.

  18. Dimers in nucleating vapors

    NASA Astrophysics Data System (ADS)

    Lushnikov, A. A.; Kulmala, M.

    1998-09-01

    The dimer stage of nucleation may affect considerably the rate of the nucleation process at high supersaturation of the nucleating vapor. Assuming that the dimer formation limits the nucleation rate, the kinetics of the particle formation-growth process is studied starting with the definition of dimers as bound states of two associating molecules. The partition function of dimer states is calculated by summing the Boltzmann factor over all classical bound states, and the equilibrium population of dimers is found for two types of intermolecular forces: the Lennard-Jones (LJ) and rectangular well+hard core (RW) potentials. The principle of detailed balance is used for calculating the evaporation rate of dimers. The kinetics of the particle formation-growth process is then investigated under the assumption that the trimers are stable with respect to evaporation and that the condensation rate is a power function of the particle mass. If the power exponent λ=n/(n+1) (n is a non-negative integer), the kinetics of the process is described by a finite set of moments of particle mass distribution. When the characteristic time of the particle formation by nucleation is much shorter than that of the condensational growth, n+2 universal functions of a nondimensional time define the kinetic process. These functions are calculated for λ=2/3 (gas-to-particle conversion in the free molecular regime) and λ=1/2 (formation of islands on surfaces).

  19. Dimer monomer transition and dimer re-formation play important role for ATM cellular function during DNA repair

    SciTech Connect

    Du, Fengxia; Zhang, Minjie; Li, Xiaohua; Yang, Caiyun; Meng, Hao; Wang, Dong; Chang, Shuang; Xu, Ye; Price, Brendan; Sun, Yingli

    2014-10-03

    Highlights: • ATM phosphorylates the opposite strand of the dimer in response to DNA damage. • The PETPVFRLT box of ATM plays a key role in its dimer dissociation in DNA repair. • The dephosphorylation of ATM is critical for dimer re-formation after DNA repair. - Abstract: The ATM protein kinase, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks, mediates responses to ionizing radiation in mammalian cells. Here we show that ATM is held inactive in unirradiated cells as a dimer and phosphorylates the opposite strand of the dimer in response to DNA damage. Cellular irradiation induces rapid intermolecular autophosphorylation of serine 1981 that causes dimer dissociation and initiates cellular ATM kinase activity. ATM cannot phosphorylate the substrates when it could not undergo dimer monomer transition. After DNA repair, the active monomer will undergo dephosphorylation to form dimer again and dephosphorylation is critical for dimer re-formation. Our work reveals novel function of ATM dimer monomer transition and explains why ATM dimer monomer transition plays such important role for ATM cellular activity during DNA repair.

  20. Dimerization of thymol blue in solution: Theoretical evidence.

    PubMed

    Balderas-Hernández, Patricia; Vargas, Rubicelia; Rojas-Hernández, Alberto; Ramírez-Silva, Ma Teresa; Galván, Marcelo

    2007-02-28

    The possibility of dimerization of thymol blue was addressed by ab initio and force field calculations. In agreement with experimental information, a dimer forming symmetrical chemical environments for hydrogen bond formation was determined. This dimer is stable in vacuum and aqueous media and corresponds to the same protonated state proposed by the experiment. A comparison of the CVFF and MM3 force fields and ab initio results shows the suitability of CVFF to qualitatively describe this system.

  1. Collective motion of dimers.

    PubMed

    Penington, Catherine J; Korvasová, Karolína; Hughes, Barry D; Landman, Kerry A

    2012-11-01

    We consider a discrete agent-based model on a one-dimensional lattice and a two-dimensional square lattice, where each agent is a dimer occupying two sites. Agents move by vacating one occupied site in favor of a nearest-neighbor site and obey either a strict simple exclusion rule or a weaker constraint that permits partial overlaps between dimers. Using indicator variables and careful probability arguments, a discrete-time master equation for these processes is derived systematically within a mean-field approximation. In the continuum limit, nonlinear diffusion equations that describe the average agent occupancy of the dimer population are obtained. In addition, we show that multiple species of interacting subpopulations give rise to advection-diffusion equations. Averaged discrete simulation data compares very well with the solution to the continuum partial differential equation models. Since many cell types are elongated rather than circular, this work offers insight into population-level behavior of collective cellular motion.

  2. Disordered clusters of Bak dimers rupture mitochondria during apoptosis

    PubMed Central

    Uren, Rachel T; O’Hely, Martin; Iyer, Sweta; Bartolo, Ray; Shi, Melissa X; Brouwer, Jason M; Alsop, Amber E; Dewson, Grant; Kluck, Ruth M

    2017-01-01

    During apoptosis, Bak and Bax undergo major conformational change and form symmetric dimers that coalesce to perforate the mitochondrial outer membrane via an unknown mechanism. We have employed cysteine labelling and linkage analysis to the full length of Bak in mitochondria. This comprehensive survey showed that in each Bak dimer the N-termini are fully solvent-exposed and mobile, the core is highly structured, and the C-termini are flexible but restrained by their contact with the membrane. Dimer-dimer interactions were more labile than the BH3:groove interaction within dimers, suggesting there is no extensive protein interface between dimers. In addition, linkage in the mobile Bak N-terminus (V61C) specifically quantified association between dimers, allowing mathematical simulations of dimer arrangement. Together, our data show that Bak dimers form disordered clusters to generate lipidic pores. These findings provide a molecular explanation for the observed structural heterogeneity of the apoptotic pore. DOI: http://dx.doi.org/10.7554/eLife.19944.001 PMID:28182867

  3. Executive function performance and change in aging is predicted by apolipoprotein E, intensified by catechol-O-methyltransferase and brain-derived neurotrophic factor, and moderated by age and lifestyle.

    PubMed

    Sapkota, Shraddha; Bäckman, Lars; Dixon, Roger A

    2017-01-03

    Recent studies have reported several genetic, health, and aging interaction effects in predicting cognitive performance and change. We used an accelerated longitudinal design to examine interactions among genetic, lifestyle, and aging for executive function (EF) in non-demented older adults (n = 634; age range = 53-95 years). The polymorphisms were apolipoprotein E (APOE), catechol-O-methyltransferase (COMT), and brain-derived neurotrophic factor (BDNF). We tested (1) independent and additive effects of APOE, COMT, and BDNF and (2) APOE effect modification for COMT + BDNF, on EF performance and 9-year change as separated by age and lifestyle activities. First, APOE ε4+ carriers had poorer EF performance and steeper 9-year decline. Second, APOE ε4+ carriers with (1) BDNF Met/Met genotype and (2) increasing allelic risk in the COMT + BDNF risk panel had poorer EF performance; these effects were moderated by lifestyle activities (composite of everyday social, physical, and cognitive activities). Examining APOE effect modification for COMT + BDNF risk panel effects with other moderating factors may help identify complex neurobiological and genetic underpinnings of polygenic phenotypes such as EF in aging.

  4. Quantitative analysis of senile plaques in Alzheimer disease: observation of log-normal size distribution and molecular epidemiology of differences associated with apolipoprotein E genotype and trisomy 21 (Down syndrome).

    PubMed Central

    Hyman, B T; West, H L; Rebeck, G W; Buldyrev, S V; Mantegna, R N; Ukleja, M; Havlin, S; Stanley, H E

    1995-01-01

    The discovery that the epsilon 4 allele of the apolipoprotein E (apoE) gene is a putative risk factor for Alzheimer disease (AD) in the general population has highlighted the role of genetic influences in this extremely common and disabling illness. It has long been recognized that another genetic abnormality, trisomy 21 (Down syndrome), is associated with early and severe development of AD neuropathological lesions. It remains a challenge, however, to understand how these facts relate to the pathological changes in the brains of AD patients. We used computerized image analysis to examine the size distribution of one of the characteristic neuropathological lesions in AD, deposits of A beta peptide in senile plaques (SPs). Surprisingly, we find that a log-normal distribution fits the SP size distribution quite well, motivating a porous model of SP morphogenesis. We then analyzed SP size distribution curves in genotypically defined subgroups of AD patients. The data demonstrate that both apoE epsilon 4/AD and trisomy 21/AD lead to increased amyloid deposition, but by apparently different mechanisms. The size distribution curve is shifted toward larger plaques in trisomy 21/AD, probably reflecting increased A beta production. In apoE epsilon 4/AD, the size distribution is unchanged but the number of SP is increased compared to apoE epsilon 3, suggesting increased probability of SP initiation. These results demonstrate that subgroups of AD patients defined on the basis of molecular characteristics have quantitatively different neuropathological phenotypes. Images Fig. 2 Fig. 4 PMID:7724603

  5. Quantum Dimer Model: Phase Diagrams

    NASA Astrophysics Data System (ADS)

    Goldstein, Garry; Chamon, Claudio; Castelnovo, Claudio

    We present new theoretical analysis of the Quantum Dimer Model. We study dimer models on square, cubic and triangular lattices and we reproduce their phase diagrams (which were previously known only numerically). We show that there are several types of dimer liquids and solids. We present preliminary analysis of several other models including doped dimers and planar spin ice, and some results on the Kagome and hexagonal lattices.

  6. Evidence for dimerization of dimers in K+ channel assembly.

    PubMed Central

    Tu, L; Deutsch, C

    1999-01-01

    Voltage-gated K+ channels are tetrameric, but how the four subunits assemble is not known. We analyzed inactivation kinetics and peak current levels elicited for a variety of wild-type and mutant Kv1.3 subunits, expressed singly, in combination, and as tandem constructs, to show that 1) the dominant pathway involves a dimerization of dimers, and 2) dimer-dimer interaction may involve interaction sites that differ from those involved in monomer-monomer association. Moreover, using nondenaturing gel electrophoresis, we detected dimers and tetramers, but not trimers, in the translation reaction of Kv1.3 monomers. PMID:10096897

  7. Dimeric States of Neural- and Epithelial-Cadherins are Distinguished by the Rate of Disassembly†

    PubMed Central

    Vunnam, Nagamani; Flint, Jon; Balbo, Andrea; Schuck, Peter; Pedigo, Susan

    2011-01-01

    Epithelial- and Neural-cadherins are specifically localized at synapses in neurons which can change shape and contact surface on a time scale of seconds to months. We have focused our studies on the role of the extracellular domains of cadherins in the dynamics of synapses. The kinetics of dimer disassembly of the first two extracellular domains of E- and N-cadherin, ECAD12 and NCAD12, were studied with analytical size exclusion chromatography and sedimentation velocity. NCAD12 forms three different dimers that are distinguished by assembly conditions and kinetics of dissociation. ECAD12 dimer disassembles rapidly regardless of the calcium concentration, whereas the disassembly of NCAD12 dimers was strongly dependent on calcium concentration. In addition to the apo- and saturated-dimeric forms of NCAD12, there is a third dimeric form that is a slow exchange dimer. This third dimeric form for NCAD12, formed by decalcification of the calcium-saturated dimer, was kinetically-trapped in apo-conditions and did not disassemble over a period of months. Sedimentation velocity experiments showed that this dimer, upon addition of calcium, had similar weighted averages as calcium-saturated dimer. These studies provide evidence that the kinetics of dimer disassembly of the extracellular domains may be a major contributor to the morphological dynamics of synapses in vivo. PMID:21375242

  8. The ability of apolipoprotein E fragments to promote intraneuronal accumulation of amyloid beta peptide 42 is both isoform and size-specific

    PubMed Central

    Dafnis, Ioannis; Argyri, Letta; Sagnou, Marina; Tzinia, Athina; Tsilibary, Effie C.; Stratikos, Efstratios; Chroni, Angeliki

    2016-01-01

    The apolipoprotein (apo) E4 isoform is the strongest risk factor for late-onset Alzheimer’s disease (AD). ApoE4 is more susceptible to proteolysis than apoE2 and apoE3 isoforms and carboxyl-terminal truncated apoE4 forms have been found in AD patients’ brain. We have previously shown that a specific apoE4 fragment, apoE4-165, promotes amyloid-peptide beta 42 (Aβ42) accumulation in human neuroblastoma SK-N-SH cells and increased intracellular reactive oxygen species formation, two events considered to occur early in AD pathogenesis. Here, we show that these effects are allele-dependent and absolutely require the apoE4 background. Furthermore, the exact length of the fragment is critical since longer or shorter length carboxyl-terminal truncated apoE4 forms do not elicit the same effects. Structural and thermodynamic analyses showed that apoE4-165 has a compact structure, in contrast to other carboxyl-terminal truncated apoE4 forms that are instead destabilized. Compared however to other allelic backgrounds, apoE4-165 is structurally distinct and less thermodynamically stable suggesting that the combination of a well-folded structure with structural plasticity is a unique characteristic of this fragment. Overall, our findings suggest that the ability of apoE fragments to promote Aβ42 intraneuronal accumulation is specific for both the apoE4 isoform and the particular structural and thermodynamic properties of the fragment. PMID:27476701

  9. Precise control of quantum dot location within the P3HT-b-P2VP/QD nanowires formed by crystallization-driven 1D growth of hybrid dimeric seeds.

    PubMed

    Kim, Yong-Jae; Cho, Chul-Hee; Paek, Kwanyeol; Jo, Mijung; Park, Mi-kyoung; Lee, Na-Eun; Kim, Youn-joong; Kim, Bumjoon J; Lee, Eunji

    2014-02-19

    Herein, we report a simple fabrication of hybrid nanowires (NWs) composed of a p-type conjugated polymer (CP) and n-type inorganic quantum dots (QDs) by exploiting the crystallization-driven solution assembly of poly(3-hexylthiophene)-b-poly(2-vinylpyridine) (P3HT-b-P2VP) rod-coil amphiphiles. The visualization of the crystallization-driven growth evolution of hybrid NWs through systematic transmission electron microscopy experiments showed that discrete dimeric CdSe QDs bridged by P3HT-b-P2VP polymers were generated during the initial state of crystallization. These, in turn, assemble into elongated fibrils, forming the coaxial P3HT-b-P2VP/QDs hybrid NWs. In particular, the location of the QD arrays within the single strand of P3HT-b-P2VP can be controlled precisely by manipulating the regioregularity (RR) values of P3HT block and the relative lengths of P2VP block. The degree of coaxiality of the QD arrays was shown to depend on the coplanarity of the thiophene rings of P3HT block, which can be controlled by the RR value of P3HT block. In addition, the location of QDs could be regulated at the specific-local site of P3HT-b-P2VP NW according to the surface characteristics of QDs. As an example, the comparison of two different QDs coated with hydrophobic alkyl-terminated and hydroxyl-terminated molecules, respectively, is used to elucidate the effect of the surface properties of QDs on their nanolocation in the NW.

  10. Detection of alpha-helical coiled-coil dimer formation by spin-labeled synthetic peptides: a model parallel coiled-coil peptide and the antiparallel coiled coil formed by a replica of the ProP C-terminus.

    PubMed

    Hillar, Alexander; Tripet, Brian; Zoetewey, David; Wood, Janet M; Hodges, Robert S; Boggs, Joan M

    2003-12-30

    Electron paramagnetic resonance spectroscopy was used to determine relative peptide orientation within homodimeric, alpha-helical coiled-coil structures. Introduction of cysteine (Cys) residues into peptides/proteins for spin labeling allows detection of their oligomerization from exchange broadening or dipolar interactions between residues within 25 A of each other. Two synthetic peptides containing Cys substitutions were used: a 35-residue model peptide and the 30-residue ProP peptide. The model peptide is known to form a stable, parallel homodimeric coiled coil, which is partially destabilized by Cys substitutions at heptad a and d positions (peptides C30a and C33d). The ProP peptide, a 30-residue synthetic peptide, corresponds to residues 468-497 of osmoregulatory transporter ProP from Escherichia coli. It forms a relatively unstable, homodimeric coiled coil that is predicted to be antiparallel in orientation. Cys was introduced in heptad g positions of the ProP peptide, near the N-terminus (K473C, creating peptide C473g) or closer to the center of the sequence (E480C, creating peptide C480g). In contrast to the destabilizing effect of Cys substitution at the core heptad a or d positions of model peptides C30a and C33d, circular dichroism spectroscopy showed that Cys substitutions at the heptad g positions of the ProP peptide had little or no effect on coiled-coil stability. Thermal denaturation analysis showed that spin labeling increased the stability of the coiled coil for all peptides. Strong exchange broadening was detected for both C30a and C33d, in agreement with a parallel structure. EPR spectra of C480g had a large hyperfine splitting of about 90 G, indicative of strong dipole-dipole interactions and a distance between spin-labeled residues of less than 9 A. Spin-spin interactions were much weaker for C473g. These results supported the hypothesis that the ProP peptide primarily formed an antiparallel coiled coil, since formation of a parallel dimer

  11. Identification of a new structural variant of human apolipoprotein E, E2(Lys146 leads to Gln), in a type III hyperlipoproteinemic subject with the E3/2 phenotype.

    PubMed Central

    Rall, S C; Weisgraber, K H; Innerarity, T L; Bersot, T P; Mahley, R W; Blum, C B

    1983-01-01

    A type III hyperlipoproteinemic subject having the apolipoprotein E (apo E) phenotype E3/2 was identified. From isoelectric focusing experiments in conjunction with cysteamine treatment (a method that measures cysteine content in apo E), the E2 isoform of this subject was determined to have only one cysteine residue, in contrast to all previously studied E2 apoproteins, which had two cysteines. This single cysteine was shown to be at residue 112, the same site at which it occurs in apo E3. From amino acid and sequence analyses, it was determined that this apo E2 differed from apo E3 by the occurrence of glutamine rather than lysine at residue 146. When phospholipid X protein recombinants of the subject's isolated E3 and E2 isoforms were tested for their ability to bind to the human fibroblast apo-B,E receptor, it was found that the E3 bound normally (compared with an apo E3 control) but that the E2 had defective binding (approximately 40% of normal). Although they contained E3 as well as E2, the beta-very low density lipoproteins (beta-VLDL) from this subject were very similar in character to the beta-VLDL from an E2/2 type III hyperlipoproteinemic subject; similar subfractions could be obtained from each subject and were shown to have a similar ability to stimulate cholesteryl ester accumulation in mouse peritoneal macrophages. The new apo E2 variant has also been detected in a second type III hyperlipoproteinemic subject. Images PMID:6313758

  12. Compared with saturated fatty acids, dietary monounsaturated fatty acids and carbohydrates increase atherosclerosis and VLDL cholesterol levels in LDL receptor-deficient, but not apolipoprotein E-deficient, mice.

    PubMed

    Merkel, M; Velez-Carrasco, W; Hudgins, L C; Breslow, J L

    2001-11-06

    Heart-healthy dietary recommendations include decreasing the intake of saturated fatty acids (SFA). However, the relative benefit of replacing SFA with monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), or carbohydrates (CARB) is still being debated. We have used two mouse models of atherosclerosis, low density lipoprotein receptor-deficient (LDLRKO) and apolipoprotein E-deficient (apoEKO) mice to measure the effects of four isocaloric diets enriched with either SFA, MUFA, PUFA, or CARB on atherosclerotic lesion area and lipoprotein levels. In LDLRKO mice, compared with the SFA diet, the MUFA and CARB diets significantly increased atherosclerosis in both sexes, but the PUFA diet had no effect. The MUFA and CARB diets also increased very low density lipoprotein-cholesterol (VLDL-C) and LDL-cholesterol (LDL-C) in males and VLDL-C levels in females. Analysis of data from LDLRKO mice on all diets showed that atherosclerotic lesion area correlated positively with VLDL-C levels (males: r = 0.47, P < 0.005; females: r = 0.52, P < 0.001). In contrast, in apoEKO mice there were no significant dietary effects on atherosclerosis in either sex. Compared with the SFA diet, the CARB diet significantly decreased VLDL-C in males and the MUFA, PUFA, and CARB diets decreased VLDL-C and the CARB diet decreased LDL-C in females. In summary, in LDLRKO mice the replacement of dietary SFA by either MUFA or CARB causes a proportionate increase in both atherosclerotic lesion area and VLDL-C. There were no significant dietary effects on atherosclerotic lesion area in apoEKO mice. These results are surprising and suggest that, depending on the underlying genotype, dietary MUFA and CARB can actually increase atherosclerosis susceptibility, probably by raising VLDL-C levels through a non-LDL receptor, apoE-dependent pathway.

  13. Effects of Tooth Loss and the Apolipoprotein E ɛ4 Allele on Mild Memory Impairment in the Fujiwara-kyo Study of Japan: A Nested Case-Control Study

    PubMed Central

    Okamoto, Nozomi; Morikawa, Masayuki; Amano, Nobuko; Yanagi, Motokazu; Takasawa, Shin; Kurumatani, Norio

    2016-01-01

    Background: Several studies have suggested that periodontal disease can exacerbate the pro-inflammatory status of the brain. Tooth loss is one of the alternative evaluation indices of periodontal disease. There are few data on the relationship between tooth loss and memory impairment, depending on the apolipoprotein E (APOE) ɛ4 genotype. Objective: To determine if tooth loss is associated with mild memory impairment (MMI) and if this association is modified by the presence of the APOE ɛ4 allele. Methods: A nested case-control study was conducted from 2007 to 2012 in Japan. Five hundred and thirty-seven Japanese subjects aged 65 years and over who were cognitively intact at baseline were analyzed. MMI at follow-up was evaluated. Results: The median number of teeth at baseline was significantly lower in MMI participants (n = 179) than in controls (n = 358) (MMI: median 21.0, interquartile range 10.0–25.0 versus controls: 24.0, 14.0–27.0). After adjustment for demographics, vascular risk factors, and APOE ɛ4 allele, the multivariate adjusted odds ratio (OR) of ≤8 teeth was 1.97 (95% confidence interval [CI], 1.13–3.44) compared to 25–32 teeth. Participants with both the presence of at least 1 APOE ɛ4 allele and ≤8 teeth had a higher risk of MMI compared with those with neither (OR, 2.82; 95% CI, 1.15–6.91). Those with either risk factor alone did not have a higher risk of MMI. Conclusions: A lower number of teeth is related to risk of MMI. This may be primarily true for those individuals with an APOE ɛ4 allele. PMID:27716671

  14. The role of Alzheimer’s and cerebrovascular pathology in mediating the effects of age, race, and apolipoprotein E genotype on dementia severity in pathologically confirmed Alzheimer’s disease

    PubMed Central

    Gavett, Brandon E.; John, Samantha E.; Gurnani, Ashita S.; Bussell, Cara A.; Saurman, Jessica L.

    2016-01-01

    Background Dementia severity can be modeled as the construct δ, representing the “cognitive correlates of functional status.” Objective We recently validated a model for estimating δ in the National Alzheimer’s Coordinating Center’s Uniform Data Set; however, δ’s association with neuropathology remains untested. Methods We used data from 727 decedents evaluated at Alzheimer’s Disease (AD) Centers nationwide. Participants spoke English, had no genetic abnormalities, and were pathologically diagnosed with AD as a primary or contributing etiology. Clinical data from participants’ last visit prior to death were used to estimate dementia severity (δ). Results A structural equation model using age, education, race, and apolipoprotein E (APOE) genotype (number of ε2 and ε4 alleles) as predictors and latent AD pathology and cerebrovascular disease (CVD) pathology as mediators fit the data well (RMSEA = 0.031; CFI = .957). AD pathology mediated the effects of age and APOE genotype on dementia severity. An older age at death and more ε2 alleles were associated with less AD pathology and, in turn, with less severe dementia. In contrast, more ε4 alleles were associated with more pathology and more severe dementia. Although age and race contributed to differences in CVD pathology, CVD pathology was not related to dementia severity in this sample of decedents with pathologically confirmed AD. Conclusions Using δ as an estimate of dementia severity fits well within a structural model in which AD pathology directly affects dementia severity and mediates the relationship between age and APOE genotype on dementia severity. PMID:26444761

  15. The effect of galantamine on brain atrophy rate in subjects with mild cognitive impairment is modified by apolipoprotein E genotype: post-hoc analysis of data from a randomized controlled trial

    PubMed Central

    2014-01-01

    Introduction The aim of this investigation was to assess the effect of galantamine, an acetylcholinesterase inhibitor and allosteric modulator of nicotinic receptors, on brain atrophy in individuals with mild cognitive impairment (MCI), and to assess effect modification by apolipoprotein E (APOE) genotype. Methods We used data from the Galantamine-International-11 (Gal-Int-11) trial, a 24-month, randomized, double blind, placebo-controlled, flexible-dose (16 to 24 mg daily) study in patients with MCI. Brain magnetic resonance imaging (MRI), including a 3-dimensional T1-weighted gradient echo volumetric sequence, was performed at screening and at 24 months. We recorded whole brain and hippocampal volumes, and calculated annual atrophy rates. Linear regression analysis was used to calculate adjusted mean differences in the rate of whole brain and hippocampal atrophy, between MCI patients treated with galantamine and with placebo. Additionally, we performed stratified analyses according to APOE genotype. Results Data from 364 MCI patients with 24-month MRI data (galantamine, n = 176; placebo, n = 188) were included in the volumetric analysis. Subjects treated with galantamine demonstrated a lower rate of whole brain atrophy compared to those treated with placebo (adjusted mean difference 0.18% per year (95% confidence interval (CI) 0.04; 0.30)). Stratified analyses according to APOE genotype, showed that this effect was confined to patients who carried an APOE ϵ4 allele (adjusted mean difference 0.28% per year (95% CI 0.07; 0.50)). Rates of hippocampal atrophy did not differ significantly between study groups. Conclusions Patients with MCI who were treated with galantamine demonstrated a lower rate of whole brain atrophy, but not of hippocampal atrophy, over a 24-month treatment period, compared to those treated with placebo. This protective effect of galantamine on whole brain atrophy rate in MCI was only present in APOE ϵ4 carriers. PMID:25478019

  16. Anti-β2 glycoprotein I antibodies in complex with β2 glycoprotein I induce platelet activation via two receptors: apolipoprotein E receptor 2' and glycoprotein I bα.

    PubMed

    Zhang, Wenjing; Gao, Fei; Lu, Donghe; Sun, Na; Yin, Xiaoxue; Jin, Meili; Liu, Yanhong

    2016-03-01

    Anti-β2 glycoprotein I (anti-β2GPI ) antibodies are important contributors to thrombosis, especially in patients with antiphospholipid syndrome (APS). However, the mechanism by which anti-β2GPI antibodies are involved in the pathogenesis of thrombosis is not fully understood. In this report, we investigated the role of anti- β2GPI antibodies in complexes with β2GPI as mediators of platelet activation, which can serve as a potential source contributing to thrombosis. We examined the involvement of the apolipoprotein E receptor 2' (apoER2') and glycoprotein I ba (GP I ba) in platelet activation induced by the anti-β2GPI /β2GPI complex. The interaction between the anti-β2GPI /β2GPI complex and platelets was examined using in vitro methods, in which the Fc portion of the antibody was immobilized using protein A coated onto a microtiter plate. Platelet activation was assessed by measuring GPII b/III a activation and P-selectin expression and thromboxane B2 production as well as p38 mitogen-activated protein kinase phosphorylation. Our results revealed that the anti-β2GPI /β2GPI complex was able to activate platelets, and this activation was inhibited by either the anti-GP I bα antibody or the apoER2' inhibitor. Results showed that the anti-β2GPI /β2GPI complex induced platelet activation via GPI ba and apoER2', which may then contribute to the prothrombotic tendency in APS patients.

  17. Dynamical dimer-dimer correlation functions from exact diagonalization

    SciTech Connect

    Werner, Ralph

    2001-05-01

    A regularization method is presented to deduce dynamic correlation functions from exact diagonalization calculations. It is applied to dimer-dimer correlation functions in quantum spin chains relevant for the description of spin-Peierls systems. Exact results for the XY model are presented. The analysis draws into doubt that the dimer-dimer correlation functions show the same scale invariance as spin-spin correlation functions. The results are applied to describe the quasielastic scattering in CuGeO{sub 3} and the hardening of the Peierls-active phonons.

  18. The acrylonitrile dimer ion

    NASA Astrophysics Data System (ADS)

    Ervasti, Henri K.; Jobst, Karl J.; Burgers, Peter C.; Ruttink, Paul J. Ae; Terlouw, Johan K.

    2007-04-01

    Large energy barriers prohibit the rearrangement of solitary acrylonitrile ions, CH2CHCN+, into their more stable hydrogen-shift isomers CH2CCNH+ or CHCH-CNH+. This prompted us to examine if these isomerizations occur by self-catalysis in acrylonitrile dimer ions. Such ions, generated by chemical ionization experiments of acrylonitrile with an excess of carbon dioxide, undergo five dissociations in the [mu]s time frame, as witnessed by peaks at m/z 53, 54, 79, 80 and 105 in their metastable ion mass spectrum. Collision experiments on these product ions, deuterium labeling, and a detailed computational analysis using the CBS-QB3 model chemistry lead to the following conclusions: (i) the m/z 54 ions are ions CH2CHCNH+ generated by self-protonation in ion-dipole stabilized hydrogen-bridged dimer ions [CH2CHCN...H-C(CN)CH2]+ and [CH2CHCN...H-C(H)C(H)CN]+; the proton shifts in these ions are associated with a small reverse barrier; (ii) dissociation of the H-bridged ions into CH2CCNH+ or CHCH-CNH+ by self-catalysis is energetically feasible but kinetically improbable: experiment shows that the m/z 53 ions are CH2CHCN+ ions, generated by back dissociation; (iii) the peaks at m/z 79, 80 and 105 correspond with the losses of HCN, C2H2 and H, respectively. The calculations indicate that these ions are generated from dimer ions that have adopted the (much more stable) covalently bound "head-to-tail" structure [CH2CHCN-C(H2)C(H)CN]+; experiments indicate that the m/z 79 (C5H5N) and m/z 105 (C6H6N2) ions have linear structures but the m/z 80 (C4H4N2) ions consist of ionized pyrimidine in admixture with its stable pyrimidine-2-ylidene isomer. Acrylonitrile is a confirmed species in interstellar space and our study provides experimental and computational evidence that its dimer radical cation yields the ionized prebiotic pyrimidine molecule.

  19. Metallothionein dimers studied by nano-spray mass spectrometry.

    PubMed

    Hathout, Yetrib; Reynolds, Kristy J; Szilagyi, Zoltan; Fenselau, Catherine

    2002-01-15

    Both transient and stable dimers of metallothionein have been characterized, based on earlier studies using NMR, circular dichroism and size-exclusion chromatography. Here additional characterization is provided by nanospray mass spectrometry. Rapid redistribution of metal ions between monomeric Cd7- and Zn7-metallothionein 2a is monitored by nanospray. An experiment in which theses two forms of the monomeric protein are separated by a dialysis membrane, which will pass metal ions but not proteins, confirms that a transient dimer must form for metal ions to be redistributed. On the other hand, size-exclusion chromatography of reconstituted Zn7- or Cd7-metallothionein revealed the presence of monomeric and dimeric species. These dimers do not equilibrate readily to form monomers and they are shown to be covalent.

  20. Calcium-dependent Dimerization of Human Soluble Calcium Activated Nucleotidase: Characterization of the Dimer Interface

    SciTech Connect

    Yang,M.; Horii, K.; Herr, A.; Kirley, T.

    2006-01-01

    Mammals express a protein homologous to soluble nucleotidases used by blood-sucking insects to inhibit host blood clotting. These vertebrate nucleotidases may play a role in protein glycosylation. The activity of this enzyme family is strictly dependent on calcium, which induces a conformational change in the secreted, soluble human nucleotidase. The crystal structure of this human enzyme was recently solved; however, the mechanism of calcium activation and the basis for the calcium-induced changes remain unclear. In this study, using analytical ultracentrifugation and chemical cross-linking, we show that calcium or strontium induce noncovalent dimerization of the soluble human enzyme. The location and nature of the dimer interface was elucidated using a combination of site-directed mutagenesis and chemical cross-linking, coupled with crystallographic analyses. Replacement of Ile{sup 170}, Ser{sup 172}, and Ser{sup 226} with cysteine residues resulted in calcium-dependent, sulfhydryl-specific intermolecular cross-linking, which was not observed after cysteine introduction at other surface locations. Analysis of a super-active mutant, E130Y, revealed that this mutant dimerized more readily than the wild-type enzyme. The crystal structure of the E130Y mutant revealed that the mutated residue is found in the dimer interface. In addition, expression of the full-length nucleotidase revealed that this membrane-bound form can also dimerize and that these dimers are stabilized by spontaneous oxidative cross-linking of Cys{sup 30}, located between the single transmembrane helix and the start of the soluble sequence. Thus, calcium-mediated dimerization may also represent a mechanism for regulation of the activity of this nucleotidase in the physiological setting of the endoplasmic reticulum or Golgi.

  1. D Dimer in acute care

    PubMed Central

    Sathe, Prachee M.; Patwa, Urvil D.

    2014-01-01

    Pulmonary embolism, Deep Vein Thrombosis (DVT) and Disseminated intravascular coagulation (DIC) are important sources of mortality and morbidity in intensive care unit (ICU). And every time D-dimer remains the the commonest investigation. Many times D-dimer is erroneously considered as a diagnostic test in above mentioned conditions. Its interpretation requires cautions. To circumvent this source of error it is necessary to understand D-dimer test and its significance in various disorder. This article review some basic details of D-dimer, condition associated with its increased level and some prognostic value in intracranial hemorrhage and gastrointestinal (GI) bleed. PMID:25337485

  2. ApoE (Apolipoprotein E) Genotyping

    MedlinePlus

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  3. Fluxional σ-Bonds of the 2,5,8-Trimethylphenalenyl Dimer: Direct Observation of the Sixfold σ-Bond Shift via a π-Dimer.

    PubMed

    Uchida, Kazuyuki; Mou, Zhongyu; Kertesz, Miklos; Kubo, Takashi

    2016-04-06

    Direct evidence for σ-bond fluxionality in a phenalenyl σ-dimer was successfully obtained by a detailed investigation of the solution-state dynamics of 2,5,8-trimethylphenalenyl (TMPLY) using both experimental and theoretical approaches. TMPLY formed three diamagnetic dimers, namely, the σ-dimer (RR/SS), σ-dimer (RS), and π-dimer, which were fully characterized by (1)H NMR spectroscopy and electronic absorption measurements. The experimental findings gave the first quantitative insights into the essential preference of these competitive and unusual dimerization modes. The spectroscopic analyses suggested that the σ-dimer (RR/SS) is the most stable in terms of energy, whereas the others are metastable; the energy differences between these three isomers are less than 1 kcal mol(-1). Furthermore, the intriguing dynamics of the TMPLY dimers in the solution state were fully revealed by means of (1)H-(1)H exchange spectroscopy (EXSY) measurements and variable-temperature (1)H NMR studies. Surprisingly, the σ-dimer (RR/SS) demonstrated a sixfold σ-bond shift between the six sets of α-carbon pairs. This unusual σ-bond fluxionality is ascribed to the presence of a direct interconversion pathway between the σ-dimer (RR/SS) and the π-dimer, which was unambiguously corroborated by the EXSY measurements. The proposed mechanism of the sixfold σ-bond shift based on the experimental findings was well-supported by theoretical calculations.

  4. [Dichotomizing method applied to calculating equilibrium constant of dimerization system].

    PubMed

    Cheng, Guo-zhong; Ye, Zhi-xiang

    2002-06-01

    The arbitrary trivariate algebraic equations are formed based on the combination principle. The univariata algebraic equation of equilibrium constant kappa for dimerization system is obtained through a series of algebraic transformation, and it depends on the properties of monotonic functions whether the equation is solvable or not. If the equation is solvable, equilibrium constant of dimerization system is obtained by dichotomy and its final equilibrium constant of dimerization system is determined according to the principle of error of fitting. The equilibrium constants of trisulfophthalocyanine and biosulfophthalocyanine obtained with this method are 47,973.4 and 30,271.8 respectively. The results are much better than those reported previously.

  5. Scattering properties of weakly-bound dimers of Fermi atoms

    NASA Astrophysics Data System (ADS)

    Petrov, Dmitry

    2005-03-01

    We discuss the behavior of weakly bound bosonic dimers formed in a two-component Fermi gas with a large positive scattering length for the interspecies interaction. We present a theoretical approach for solving a few-body scattering problem and describe the physics of dimer-dimer elastic and inelastic scattering. We explain why these diatomic molecules, while in the highest ro-vibrational level, are characterized by remarkable collisional stability. Co-authors are Christophe Salomon, LKB, Ecole Normale Superieure, Paris, France; Georgy Shlyapnikov, LPTMS, University of South Paris, Orsay, France.

  6. Dimer model for Tau proteins bound in microtubule bundles

    NASA Astrophysics Data System (ADS)

    Hall, Natalie; Kluber, Alexander; Hayre, N. Robert; Singh, Rajiv; Cox, Daniel

    2013-03-01

    The microtubule associated protein tau is important in nucleating and maintaining microtubule spacing and structure in neuronal axons. Modification of tau is implicated as a later stage process in Alzheimer's disease, but little is known about the structure of tau in microtubule bundles. We present preliminary work on a proposed model for tau dimers in microtubule bundles (dimers are the minimal units since there is one microtubule binding domain per tau). First, a model of tau monomer was created and its characteristics explored using implicit solvent molecular dynamics simulation. Multiple simulations yield a partially collapsed form with separate positively/negatively charged clumps, but which are a factor of two smaller than required by observed microtubule spacing. We argue that this will elongate in dimer form to lower electrostatic energy at a cost of entropic ``spring'' energy. We will present preliminary results on steered molecular dynamics runs on tau dimers to estimate the actual force constant. Supported by US NSF Grant DMR 1207624.

  7. Increased apolipoprotein E and c-fms gene expression without elevated interleukin 1 or 6 mRNA levels indicates selective activation of macrophage functions in advanced human atheroma.

    PubMed Central

    Salomon, R N; Underwood, R; Doyle, M V; Wang, A; Libby, P

    1992-01-01

    Cells found within atherosclerotic lesions can produce in culture protein mediators that may participate in atherogenesis. To test whether human atheromata actually contain transcripts for certain of these genes, we compared levels of mRNAs in carotid or coronary atheromata and in nonatherosclerotic human vessels by polymerase chain reaction (PCR) amplification of cDNAs reverse-transcribed from RNA. We measured PCR products (generated during exponential amplification) by incorporation of 32P-labeled primers. Levels of interleukin 1 alpha, 1 beta, or 6 mRNAs in plaques and controls did not differ. Compared to uninvolved vessels, plaques did contain higher levels of mRNA encoding platelet-derived growth factor A chain (42 +/- 24 vs. 12 +/- 10 fmol of product; mean +/- SD; n = 8 and 8, respectively; P = 0.007) and B chain (41 +/- 36 vs. 4 +/- 3 fmol of product, n = 14 and 6, respectively; P = 0.024). Atherosclerotic lesions consistently had much higher levels of apolipoprotein E (apoE) mRNA than did control vessels (131 +/- 71 vs. 5 +/- 3 fmol of product; n = 12 and 10, respectively; P less than 0.001). Direct RNA blot analyses confirmed elevated levels of apoE mRNA in plaque extracts. To test whether mononuclear phagocytes might be a source of the apoE mRNA, we studied a selective marker for cells of the monocytic lineage, the c-fms protooncogene, which encodes the receptor for macrophage colony-stimulating factor. Plaques also contained elevated levels of c-fms mRNA (30 +/- 17 vs. 5 +/- 3 fmol of product; n = 10 and 7, respectively; P = 0.002). Immunohistochemical colocalization demonstrated apoE protein in association with macrophages in plaques, whereas nonatherosclerotic vessels showed no immunoreactive apoE. ApoE produced locally in atheroma might modulate the functions of lesional T cells or promote "reverse cholesterol transport" by associating with high density lipoprotein particles, thus targeting them for peripheral uptake. Macrophages within the advanced

  8. Relationship between hemodynamics and atherosclerosis in aortic arches of apolipoprotein E-null mice on 129S6/SvEvTac and C57BL/6J genetic backgrounds

    PubMed Central

    Tomita, Hirofumi; Hagaman, John; Friedman, Morton H.; Maeda, Nobuyo

    2011-01-01

    Objective We investigated the relationships between hemodynamics and differential plaque development at the aortic arch of apolipoprotein E (apoE)-null mice on 129S6/SvEvTac (129) and C57BL/6J (B6) genetic backgrounds. Methods Mean flow velocities at the ascending and descending aorta (mVAA and mVDA) were measured by Doppler ultrasound in wild type and apoE-null male mice at 3 and 9 months of age. Following dissection of the aortic arches, anatomical parameters and plaque areas were evaluated. Results Arch plaques were five times bigger in 129-apoE than in B6-apoE mice at 3 months, and twice as large at 9 months. The geometric differences, namely larger vessel diameter in the B6 strain and broader inner curvature of the aortic arch in the 129 strain, were exaggerated in 9-month-old apoE-null mice. Cardiac output and heart rate under anesthesia were significantly higher in the B6 strain than in the 129 strain. The values of mVAA were similar in the two strains, while mVDA was lower in the 129 strain. However, there was a 129-apoE-specific reduction of flow velocities with age, and both mVAA and mVDA were significantly lower in 129-apoE than in B6-apoE mice at 9 months. The mean relative wall shear stress (rWSS) over the aortic arch in 129-apoE and B6-apoE mice were not different, but animals with lower mean rWSS had larger arch plaques within each strain. Conclusions The plaque formation in the arch of apoE-null mice is accompanied by strain-dependent changes in both arch geometry and hemodynamics. While arch plaque sizes negatively correlate with mean rWSS, additional factors are necessary to account for the strain differences in arch plaque development. PMID:22078246

  9. Final report on the amended safety assessment of diisopropyl dimer dilinoleate, dicetearyl dimer dilinoleate, diisostearyl dimer dilinoleate, dioctyl dimer dilinoleate, dioctyldodecyl dimer dilinoleate, and ditridecyl dimer dilinoleate.

    PubMed

    Fiume, Monice Zondlo

    2003-01-01

    Diisopropyl Dimer Dilinoleate, Dicetearyl Dimer Dilinoleate, Diisostearyl Dimer Dilinoleate, Dioctyl Dimer Dilinoleate, Dioctyldodecyl Dimer Dilinoleate, and Ditridecyl Dimer Dilinoleate are diesters of their respective alcohols and dilinoleic acid. They function as skin-conditioning agents in a variety of cosmetic products at concentrations around 10%, but may be used at concentrations up to 53% in lipsticks. These ingredients do not absorb radiation in the ultraviolet (UV) UVA or UVB range and the only impurities expected are <0.5% dilinoleic acid, <0.1% isopropyl alcohol or <1% isostearyl alcohol, and/or small amounts of dilinoleic acid and cetearyl alcohol or octyldodecanol, depending on which diester is used. The potential skin penetration of these ingredients was evaluated using an estimate of the octanol/water partition coefficient (logP of 17.7) based on the structure of Diisopropyl Dimer Dilinoleate. This is consistent with the insolubility of these ingredients in water. Safety test data on dilinoleic acid (no adverse effects) were considered relevant because dilinoleic acid is a component of these diesters and a likely breakdown product. The acute oral and dermal LD(50) values for rats of Diisopropyl, Diisostearyl, and Dioctyldodecyl Dimer Dilinoleate were >5.0 g/kg. In a subchronic feeding study, macrophage aggregation was seen in the mesenteric lymph node at the lowest dose level (0.1% in the diet). These ingredients did not produce skin or ocular irritation in animal tests, nor were they comedogenic. Ames testing, clastogenesis in human lymphocytes in culture, and L5178Y mouse lymphoma cell forward mutations were all negative, indicating no dilinoleic acid genotoxicity. No carcinogenicity or reproductive/developmental toxicity data were available; however, structural alerts that would suggest a mutagenic or carcinogenic risk are absent. Significant reproductive/developmental toxicity or other systemic toxicity is not expected with these ingredients

  10. An algebra of dimerization and its implications for G-protein coupled receptor signaling.

    PubMed

    Woolf, Peter J; Linderman, Jennifer J

    2004-07-21

    Many species of receptors form dimers, but how can we use this information to make predictions about signal transduction? This problem is particularly difficult when receptors dimerize with many different species, leading to a combinatoric increase in the possible number of dimer pairs. As an example system, we focus on receptors in the G-protein coupled receptor (GPCR) family. GPCRs have been shown to reversibly form dimers, but this dimerization does not directly affect signal transduction. Here we present a new theoretical framework called a dimerization algebra. This algebra provides a systematic and rational way to represent, manipulate, and in some cases simplify large and often complicated networks of dimerization interactions. To compliment this algebra, Monte Carlo simulations are used to predict dimerization's effect on receptor organization on the membrane, signal transduction, and internalization. These simulation results are directly comparable to various experimental measures such as fluorescence resonance energy transfer (FRET), and as such provide a link between the dimerization algebra and experimental data. As an example, we show how the algebra and computational results can be used to predict the effects of dimerization on the dopamine D2 and somatastatin SSTR1 receptors. When these predictions were compared to experimental findings from the literature, good agreement was found, demonstrating the utility of our approach. Applications of this work to the development of a novel class of dimerization-modulating drugs are also discussed.

  11. Plaquette order in a dimerized frustrated spin ladder

    NASA Astrophysics Data System (ADS)

    Shlagman, Ofer; Shimshoni, Efrat

    2014-11-01

    We study the effect of dimerization (due to, e.g., spin-Peierls instability) on the phase diagram of a frustrated antiferromagnetic spin-1/2 ladder, with weak transverse and diagonal rung coupling. Our analysis focuses on a one-dimensional version of the model (i.e., a single two-leg ladder) where we consider two forms of dimerization on the legs: columnar dimers (CDs) and staggered dimers (SDs). We examine in particular the regime of parameters (corresponding to an intermediate X X Z anisotropy) in which the leg dimerization and the rung coupling terms are equally relevant. In both the CD and SD cases, we find that the effective field theory describing the system is a self-dual sine-Gordon model, which favors ordering and the opening of a gap to excitations. The order parameter, which reflects the interplay between the leg and rung dimerization interactions, represents a crystal of 4-spin plaquettes on which longitudinal and transverse dimers are in a coherent superposition. Depending on the leg dimerization mode, these plaquettes are closed or open, however both types spontaneously break reflection symmetry across the ladder. The closed plaquettes are stable, while the open plaquette order is relatively fragile and the corresponding gap may be tuned to zero under extreme conditions. We further find that a first-order transition occurs from the plaquette order to a valence bond crystal (VBC) of dimers on the legs. This suggests that in a higher-dimensional version of this system, this variety of distinct VBC states with comparable energies leads to the formation of domains. Effectively one-dimensional gapless spinon modes on domain boundaries may account for the experimental observation of spin-liquid behavior in a physical realization of the model.

  12. Determining equilibrium constants for dimerization reactions from molecular dynamics simulations.

    PubMed

    De Jong, Djurre H; Schäfer, Lars V; De Vries, Alex H; Marrink, Siewert J; Berendsen, Herman J C; Grubmüller, Helmut

    2011-07-15

    With today's available computer power, free energy calculations from equilibrium molecular dynamics simulations "via counting" become feasible for an increasing number of reactions. An example is the dimerization reaction of transmembrane alpha-helices. If an extended simulation of the two helices covers sufficiently many dimerization and dissociation events, their binding free energy is readily derived from the fraction of time during which the two helices are observed in dimeric form. Exactly how the correct value for the free energy is to be calculated, however, is unclear, and indeed several different and contradictory approaches have been used. In particular, results obtained via Boltzmann statistics differ from those determined via the law of mass action. Here, we develop a theory that resolves this discrepancy. We show that for simulation systems containing two molecules, the dimerization free energy is given by a formula of the form ΔG ∝ ln(P(1) /P(0) ). Our theory is also applicable to high concentrations that typically have to be used in molecular dynamics simulations to keep the simulation system small, where the textbook dilute approximations fail. It also covers simulations with an arbitrary number of monomers and dimers and provides rigorous error estimates. Comparison with test simulations of a simple Lennard Jones system with various particle numbers as well as with reference free energy values obtained from radial distribution functions show full agreement for both binding free energies and dimerization statistics.

  13. Dimerization of polycyclic aromatic hydrocarbons in soot nucleation.

    PubMed

    Zhang, Hong-Bo; You, Xiaoqing; Wang, Hongmiao; Law, Chung K

    2014-02-27

    A possible pathway of soot nucleation, in which localized π electrons play an important role in binding the polycyclic aromatic hydrocarbon (PAH) molecules having multiradical characteristics to form stable polymer molecules through covalent bonds, is studied using density functional and semiempirical methods. Results show that the number of covalent bonds formed in the dimerization of two identical PAHs is determined by the radical character, and the sites to form bonds are related to the aromaticity of individual six-membered ring structure. It is further shown that the binding energy of dimerization increases linearly with the diradical character in the range relevant to soot nucleation.

  14. Circular dimers of a lambda DNA in infected, nonlysogenic Escherichia coli.

    PubMed

    Freifelder, D; Baran, N; Folkmanis, A; Freifelder, D L

    1977-09-01

    Covalently closed circular dimers of phage lambda DNA have been found in Escherichia coli infected with lambda. These dimers can be formed by either the lambda Red or Int systems, by a nonrecombinational replicative mechanism requiring the activity of the lambda O and P genes or by joining of the cohesive ends. Dimers mediated by the E. coli Rec system have not been observed. Those formed by the Int system often result from recombination between different DNA molecules; however, the Red-mediated dimers may be a result of replicative extension of a single DNA molecule. Trimers have also been observed but studied only briefly.

  15. Headgroup dimerization in methanethiol monolayers on the Au(111) surface: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Zhou, Jian-Ge; Williams, Quinton L.; Hagelberg, Frank

    2007-08-01

    A long-standing controversy related to the dimer pattern formed by S atoms in methanethiol (CH3SH) on the Au(111) surface has been resolved using density functional theory. Here, dimerization of methanethiol adsorbates on the Au(111) surface is established by computational modeling. For methylthiolate (CH3S) , it is shown that the S atoms do not dimerize at high coverage but reveal a dimer pattern at intermediate coverage. Molecular dynamics simulation at high coverage demonstrates that the observed dialkyl disulfide species are formed during the desorption process, and thus are not attached to the surface.

  16. Rotational spectra of propargyl alcohol dimer: A dimer bound with three different types of hydrogen bonds

    SciTech Connect

    Mani, Devendra; Arunan, E.

    2014-10-28

    Pure rotational spectra of the propargyl alcohol dimer and its three deuterium isotopologues have been observed in the 4 to 13 GHz range using a pulsed-nozzle Fourier transform microwave spectrometer. For the parent dimer, a total of 51 transitions could be observed and fitted within experimental uncertainty. For two mono-substituted and one bi-substituted deuterium isotopologues, a total of 14, 17, and 19 transitions were observed, respectively. The observed rotational constants for the parent dimer [A = 2321.8335(4) MHz, B = 1150.4774(2) MHz, and C = 1124.8898(2) MHz] are close to those of the most stable structure predicted by ab initio calculations. Spectra of the three deuterated isotopologues and Kraitchman analysis positively confirm this structure. Geometrical parameters and “Atoms in Molecules” analysis on the observed structure reveal that the two propargyl alcohol units in the dimer are bound by three different types of hydrogen bonds: O–H⋯O, O–H⋯π, and C–H⋯π. To the best of our knowledge, propargyl alcohol seems to be the smallest molecule forming a homodimer with three different points of contact.

  17. Cholesterol-dependent Conformational Plasticity in GPCR Dimers

    PubMed Central

    Prasanna, Xavier; Sengupta, Durba; Chattopadhyay, Amitabha

    2016-01-01

    The organization and function of the serotonin1A receptor, an important member of the GPCR family, have been shown to be cholesterol-dependent, although the molecular mechanism is not clear. We performed a comprehensive structural and dynamic analysis of dimerization of the serotonin1A receptor by coarse-grain molecular dynamics simulations totaling 3.6 ms to explore the molecular details of its cholesterol-dependent association. A major finding is that the plasticity and flexibility of the receptor dimers increase with increased cholesterol concentration. In particular, a dimer interface formed by transmembrane helices I-I was found to be sensitive to cholesterol. The modulation of dimer interface appears to arise from a combination of direct cholesterol occupancy and indirect membrane effects. Interestingly, the presence of cholesterol at the dimer interface is correlated with increased dimer plasticity and flexibility. These results represent an important step in characterizing the molecular interactions in GPCR organization with potential relevance to therapeutic interventions. PMID:27535203

  18. Mobile Monomers and Dimers in Precipitation Kinetics: a Microscopic Approach.

    PubMed

    Berim, Gersh O; Brim, Lana I; Ruckenstein, Eli

    2017-02-02

    A microscopic theory of precipitation kinetics in solution developed previously by Ruckenstein and co-workers [ Dadyburjor , D. B. ; Ruckenstein , E. J. Cryst. Growth 1977 , 40 , 279 - 290 ; Bhakta , A. ; Ruckenstein , E. J. Chem. Phys. 1995 , 103 , 7120 - 7135 ] is generalized. The processes (not considered in the original approach) of monomer-monomer agglomeration, leading to the creation of dimers, as well as absorption (emission) of dimers by solute particles due to dimer mobility are included in the theory. The theory is applied to a model system in which particles grow up to a certain largest size and then precipitate from solution. The most important change in the system kinetics due to those two processes (monomer agglomeration to form dimers and dimer absorption and emission) is tremendous slowing of the asymptotic time behavior of the concentration of particles of largest size. This can be used to obtain experimental evidence for agglomeration of monomers and dimer mobility in the kinetics of real systems. The effect of trimer absorption (emission) is estimated, and it is shown that it is negligible in many situations.

  19. Magneto-association near an atom-dimer resonance

    NASA Astrophysics Data System (ADS)

    Luo, D.; Nguyen, J. H. V.; Hulet, R. G.

    2015-05-01

    Over the past decade the universal scaling of Efimov trimers has been explored in various atomic species by measuring the three-body loss coefficient. An enhancement of the three-body loss at the atom-dimer resonance has been observed, but remains unexplained. It has been attributed to an ``avanlanche mechanism'' based on resonant atom-dimer scattering, yet the effectiveness of the hypothesis is under scrutiny. We present a new piece to the puzzle. In our work, Feshbach dimers and Efimov trimers are formed near the atom-dimer resonance by RF-association, from a Bose-Einstein condensate of 7Li atoms. The molecular binding energies are tunable by the broad Feshbach resonance of the atoms in the | 1 , 1 > state. We observe that the dimer formation rate is significantly enhanced at the atom-dimer resonance. The origin of this enhanement is unclear, but it may be closely related to the enhancement of the three-body loss rate. Work supported by the NSF, ARO, and the Welch Foundation.

  20. Altered Dimer Interface Decreases Stability in an Amyloidogenic Protein

    SciTech Connect

    Baden, Elizabeth M.; Owen, Barbara A.L.; Peterson, Francis C.; Volkman, Brian F.; Ramirez-Alvarado, Marina; Thompson, James R.

    2008-07-21

    Amyloidoses are devastating and currently incurable diseases in which the process of amyloid formation causes fatal cellular and organ damage. The molecular mechanisms underlying amyloidoses are not well known. In this study, we address the structural basis of immunoglobulin light chain amyloidosis, which results from deposition of light chains produced by clonal plasma cells. We compare light chain amyloidosis protein AL-09 to its wild-type counterpart, the kl O18/O8 light chain germline. Crystallographic studies indicate that both proteins form dimers. However, AL-09 has an altered dimer interface that is rotated 90 degrees from the kl O18/O8 dimer interface. The three non-conservative mutations in AL-09 are located within the dimer interface, consistent with their role in the decreased stability of this amyloidogenic protein. Moreover, AL-09 forms amyloid fibrils more quickly than kl O18/O8 in vitro. These results support the notion that the increased stability of the monomer and delayed fibril formation, together with a properly formed dimer, may be protective against amyloidogenesis. This could open a new direction into rational drug design for amyloidogenic proteins.

  1. Thermodynamic properties for the sodium dimer

    NASA Astrophysics Data System (ADS)

    Song, Xiao-Qin; Wang, Chao-Wen; Jia, Chun-Sheng

    2017-04-01

    We present a closed-form expression of the classical vibrational partition function for the improved Rosen-Morse potential energy model. We give explicit expressions for the vibrational mean energy, vibrational specific heat, vibrational free energy, and vibrational entropy for diatomic molecule systems. The properties of these thermodynamic functions for the Na2 dimer are discussed in detail. We find that the improved Rosen-Morse potential model is superior to the harmonic oscillator in calculating the heat capacity for the Na2 molecules.

  2. Haldane relation for interacting dimers

    NASA Astrophysics Data System (ADS)

    Giuliani, Alessandro; Mastropietro, Vieri; Lucio Toninelli, Fabio

    2017-03-01

    We consider a model of weakly interacting close-packed dimers on the two-dimensional square lattice. In a previous paper, we computed both the multi-point dimer correlations, which display non-trivial critical exponents, continuously varying with the interaction strength; and the height fluctuations, which, after proper coarse graining and rescaling, converge to a massless Gaussian field with a suitable interaction-dependent pre-factor (‘amplitude’). In this paper, we prove the identity between the critical exponent of the two-point dimer correlation and the amplitude of this massless Gaussian field. This identity is the restatement, in the context of interacting dimers, of one of the Haldane universality relations, part of his Luttinger-liquid conjecture, originally formulated in the context of one-dimensional interacting Fermi systems. Its validity is a strong confirmation of the effective massless Gaussian field description of the interacting dimer model, which was proposed on the basis of formal bosonization arguments. We also conjecture that a certain discrete curve defined at the lattice level via the Temperley bijection converges in the scaling limit to an SLE κ process, with κ depending non-trivially on the interaction and related in a simple way to the amplitude of the limiting Gaussian field.

  3. Products and mechanism of acene dimerization. A computational study.

    PubMed

    Zade, Sanjio S; Zamoshchik, Natalia; Reddy, A Ravikumar; Fridman-Marueli, Galit; Sheberla, Dennis; Bendikov, Michael

    2011-07-20

    The high reactivity of acenes can reduce their potential applications in the field of molecular electronics. Although pentacene is an important material for use in organic field-effect transistors because of its high charge mobility, its reactivity is a major disadvantage hindering the development of pentacene applications. In this study, several reaction pathways for the thermal dimerization of acenes were considered computationally. The formation of acene dimers via a central benzene ring and the formation of acene-based polymers were found to be the preferred pathways, depending on the length of the monomer. Interestingly, starting from hexacene, acene dimers are thermodynamically disfavored products, and the reaction pathway is predicted to proceed instead via a double cycloaddition reaction (polymerization) to yield acene-based polymers. A concerted asynchronous reaction mechanism was found for benzene and naphthalene dimerization, while a stepwise biradical mechanism was predicted for the dimerization of anthracene, pentacene, and heptacene. The biradical mechanism for dimerization of anthracene and pentacene proceeds via syn or anti transition states and biradical minima through stepwise biradical pathways, while dimerization of heptacene proceeds via asynchronous ring closure of the complex formed by two heptacene molecules. The activation barriers for thermal dimerization decrease rapidly with increasing acene chain length and are calculated (at M06-2X/6-31G(d)+ZPVE) to be 77.9, 57.1, 33.3, -0.3, and -12.1 kcal/mol vs two isolated acene molecules for benzene, naphthalene, anthracene, pentacene, and heptacene, respectively. If activation energy is calculated vs the initially formed complex of two acene molecules, then the calculated barriers are 80.5, 63.2, 43.7, 16.7, and 12.3 kcal/mol. Dimerization is exothermic from anthracene onward, but it is endothermic at the terminal rings, even for heptacene. Phenyl substitution at the most reactive meso

  4. The first water-soluble pillar[5]arene dimer: synthesis and construction of a reversible fluorescent supramolecular polymer network in water.

    PubMed

    Sun, Yan; Wang, Jin; Yao, Yong

    2016-12-20

    The first water-soluble pillar[n]arene (n = 5) dimer was successfully synthesized. This dimer can complex with carboxylate anion-functionalized tetraphenyl ethylene to form a reversible fluorescent supramolecular polymer network in water.

  5. Adventures in holographic dimer models

    NASA Astrophysics Data System (ADS)

    Kachru, Shamit; Karch, Andreas; Yaida, Sho

    2011-03-01

    We abstract the essential features of holographic dimer models, and develop several new applications of these models. Firstly, semi-holographically coupling free band fermions to holographic dimers, we uncover novel phase transitions between conventional Fermi liquids and non-Fermi liquids, accompanied by a change in the structure of the Fermi surface. Secondly, we make dimer vibrations propagate through the whole crystal by way of double trace deformations, obtaining nontrivial band structure. In a simple toy model, the topology of the band structure experiences an interesting reorganization as we vary the strength of the double trace deformations. Finally, we develop tools that would allow one to build, in a bottom-up fashion, a holographic avatar of the Hubbard model.

  6. Generation-independent dimerization behavior of quadruple hydrogen-bond-containing oligoether dendrons.

    PubMed

    Wong, Chun-Ho; Chow, Hak-Fun; Hui, Sin-Kam; Sze, Kong-Hung

    2006-04-27

    [reaction: see text] A new series of self-assembling G1-G3 dendronized dimers bearing oligoether dendrons and a dimeric 2-ureido-4-pyrimidinone (UPy) quadruple hydrogen-bonding core were prepared and characterized. It was found that the nonpolar microenvironment created by the dendrons preserved the UPy unit in its DDAA tautomeric form. As a result, the stabilities of the dimers were exceptionally strong for all three generations (K(dim) > 2 x 10(7) M(-)(1) in CDCl(3) at 25 degrees C). Furthermore, the steric size of the dendrons did not exhibit a significant effect on their dimerization behavior.

  7. Radiation-induced tetramer-to-dimer transition of Escherichia coli lactose repressor

    SciTech Connect

    Goffinont, S.; Davidkova, M.

    2009-08-21

    The wild type lactose repressor of Escherichia coli is a tetrameric protein formed by two identical dimers. They are associated via a C-terminal 4-helix bundle (called tetramerization domain) whose stability is ensured by the interaction of leucine zipper motifs. Upon in vitro {gamma}-irradiation the repressor losses its ability to bind the operator DNA sequence due to damage of its DNA-binding domains. Using an engineered dimeric repressor for comparison, we show here that irradiation induces also the change of repressor oligomerisation state from tetramer to dimer. The splitting of the tetramer into dimers can result from the oxidation of the leucine residues of the tetramerization domain.

  8. Bivalent Ligands Targeting Chemokine Receptor Dimerization: Molecular Design and Functional Studies

    PubMed Central

    Arnatt, Christopher Kent; Zhang, Yan

    2015-01-01

    Increasing evidence has shown that chemokine receptors may form functional dimers with unique pharmacological profiles. A common practice to characterize such G protein-coupled receptor dimerization processes is to apply bivalent ligands as chemical probes which can interact with both receptors simultaneously. Currently, two chemokine receptor dimers have been studied by applying bivalent compounds: the CXCR4-CXCR4 homodimer and the CCR5-MOR heterodimer. These bivalent compounds have revealed how dimerization influences receptor function and may lead to novel therapeutics. Future design of bivalent ligands for chemokine receptor dimers may be aided with the recently available CXCR4 homodimer, and CCR5 monomer crystal structures by more accurately simulating chemokine receptors and their dimers. PMID:25159160

  9. Modulation of ceramide synthase activity via dimerization.

    PubMed

    Laviad, Elad L; Kelly, Samuel; Merrill, Alfred H; Futerman, Anthony H

    2012-06-15

    Ceramide, the backbone of all sphingolipids, is synthesized by a family of ceramide synthases (CerS) that each use acyl-CoAs of defined chain length for N-acylation of the sphingoid long chain base. CerS mRNA expression and enzymatic activity do not always correlate with the sphingolipid acyl chain composition of a particular tissue, suggesting post-translational mechanism(s) of regulation of CerS activity. We now demonstrate that CerS activity can be modulated by dimer formation. Under suitable conditions, high M(r) CerS complexes can be detected by Western blotting, and various CerS co-immunoprecipitate. CerS5 activity is inhibited in a dominant-negative fashion by co-expression with catalytically inactive CerS5, and CerS2 activity is enhanced by co-expression with a catalytically active form of CerS5 or CerS6. In a constitutive heterodimer comprising CerS5 and CerS2, the activity of CerS2 depends on the catalytic activity of CerS5. Finally, CerS dimers are formed upon rapid stimulation of ceramide synthesis by curcumin. Together, these data demonstrate that ceramide synthesis can be regulated by the formation of CerS dimers and suggest a novel way to generate the acyl chain composition of ceramide (and downstream sphingolipids), which may depend on the interaction of CerS with each other.

  10. Effects of Dimerization of Serratia marcescens Endonuclease on Water Dynamics.

    SciTech Connect

    Chen, Chuanying; Beck, Brian W.; Krause, Kurt; Weksberg, Tiffany E.; Pettitt, Bernard M.

    2007-02-15

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The dynamics and structure of Serratia marcescens endonuclease and its neighboring solvent are investigated by molecular dynamics (MD). Comparisons are made with structural and biochemical experiments. The dimer form is physiologic and functions more processively than the monomer. We previously found a channel formed by connected clusters of waters from the active site to the dimer interface. Here, we show that dimerization clearly changes correlations in the water structure and dynamics in the active site not seen in the monomer. Our results indicate that water at the active sites of the dimer is less affected compared with bulk solvent than in the monomer where it has much slower characteristic relaxation times. Given that water is a required participant in the reaction, this gives a clear advantage to dimerization in the absence of an apparent ability to use both active sites simultaneously.

  11. Crystal structure of an unknown solvate of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato-κ(4) O,N,N',O'}(N-ferrocenylisonicotinamide-κN (1))cobalt(II): a Co(II)-salen complex that forms hydrogen-bonded dimers.

    PubMed

    Brautigam, Bryan; Herholdt, Chelsea; Farnsworth, William; Brudi, Ellen; McDonald, Eric; Wu, Guang; Contakes, Stephen

    2015-09-01

    The title compound, [CoFe(C5H5)(C16H14N2O2)(C11H9N2O)], was prepared as an air-stable red-brown solid by mixing equimolar amounts of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}cobalt(II) and N-ferrocenylisonicotinamide in dry di-chloro-methane under nitro-gen and was characterized by ESI-MS, IR, and single-crystal X-ray diffraction. The structure at 100 K has triclinic (P-1) symmetry and indicates that the complex crystallizes as a mixture of λ and δ conformers. It exhibits the expected square pyramidal geometry about Co, and forms hydrogen-bonded dimers through amide N-H groups and phenolate O atoms on an adjacent mol-ecule. The involvement of only half of the salen ring structure in hydrogen-bonding inter-actions results in slight folding of the salen ring away from the pyridine coordination site in the δ conformer with an inter-salicyl-idene fold angle of 9.9 (7)°. In contrast, the λ conformer is nearly planar. The dimers pack into an open structure containing channels filled with highly disordered solvent mol-ecules. These solvent molecules' contributions to the intensity data were removed with the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9-18] available in PLATON.

  12. Dimerization of TRAF-interacting protein (TRAIP) regulates the mitotic progression.

    PubMed

    Park, I Seul; Jo, Ku-Sung; Won, Hyung-Sik; Kim, Hongtae

    2015-08-07

    The homo- or hetero-dimerization of proteins plays critical roles in the mitotic progression. The TRAF-interacting protein (TRAIP) is crucial in early mitotic progression and chromosome alignment defects in the metaphase. The TRAIP is a 469 amino acid protein, including the Really Interesting New Gene (RING), coiled-coil (CC), and leucine zipper (LZ) domain. In general, the CC or LZ domain containing proteins forms homo- or hetero-dimerization to achieve its activity. In this study, a number of TRAIP mutants were used to define the TRAIP molecular domains responsible for its homo-dimerization. A co-immunoprecipitation assay indicated that the TRAIP forms homo-dimerization through the CC domain. The cells, expressing the CC domain-deleted mutant that could not form a homo-dimer, increased the mitotic index and promoted mitotic progression.

  13. DNA melting properties of the dityrosine cross-linked dimer of Ribonuclease A.

    PubMed

    Dinda, Amit Kumar; Chattaraj, Saparya; Ghosh, Sudeshna; Tripathy, Debi Ranjan; Dasgupta, Swagata

    2016-09-01

    Several DNA binding proteins exist in dimeric form when bound with DNA to be able to exhibit various biological processes such as DNA repair, DNA replication and gene expression. Various dimeric forms of Ribonuclease A (RNase A) and other members of the ribonuclease A superfamily are endowed with a multitude of biological activities such as antitumor and antiviral activity. In the present study, we have compared the DNA binding properties between the RNase A monomer and the dityrosine (DT) cross-linked RNase A dimer, and checked the inhibitory effect of DNA on the ribonucleolytic activity of the dimeric protein. An agarose gel based assay shows that like the monomer, the dimer also binds with DNA. The number of nucleotides bound per monomer unit of the dimer is higher than the number of nucleotides that bind with the each monomer. From fluorescence measurements, the association constant (Ka) values for complexation of the monomer and the dimer with ct-DNA are (4.95±0.45)×10(4)M(-1) and (1.29±0.05)×10(6)M(-1) respectively. Binding constant (Kb) values for the binding of the monomer and the dimer with ct-DNA were determined using UV-vis spectroscopy and were found to be (4.96±1.67)×10(4)M(-1) and (4.32±0.31)×10(5)M(-1) respectively. Circular dichroism studies shows that the dimer possesses significant effect on DNA conformation. The melting profile for the ct-DNA-dimer indicated that the melting temperature (Tm) for the ct-DNA-dimer complex is lower compared to the ct-DNA-monomer complex. The ribonucleolytic activity of the dimer, like the monomer, diminishes upon binding with DNA.

  14. Synthesis and Diels-Alder cycloaddition reaction of norbornadiene and benzonorbornadiene dimers.

    PubMed

    Nişanci, Bilal; Dalkiliç, Erdin; Güney, Murat; Daştan, Arif

    2009-08-11

    Dimeric forms of norbornadiene and benzonorbornadiene were synthesized starting with known monobromide derivatives. The Diels-Alder cycloaddition reaction of dimers with TCNE and PTAD was investigated and new norbornenoid polycyclics were obtained. All compounds were characterized properly using NMR spectroscopy.

  15. Efficient electronic communication between two identical ferrocene centers in a hydrogen-bonded dimer.

    PubMed

    Sun, Hao; Steeb, Jennifer; Kaifer, Angel E

    2006-03-08

    A novel ferrocene derivative that contains a donor-donor-acceptor-acceptor (DDAA) hydrogen bonding motif forms highly stable, noncovalent dimers in chloroform and dichloromethane solutions. Its voltammetric behavior and the observation of an intervalence charge-transfer band reveal that the two equivalent ferrocene centers in the hydrogen-bonded dimer exhibit a surprisingly efficient level of electronic communication.

  16. Rotational Spectrum of Propargyl Alcohol Dimer

    NASA Astrophysics Data System (ADS)

    Mani, Devendra; Arunan, E.

    2013-06-01

    Propargyl alcohol is a molecule of interest to astrophysics as well as combustion studies. Rotational-tunneling spectra of propargyl alcohol monomer is well known and shows that the molecule exists in gauche form. Recently we reported microwave spectra of Ar...propargyl alcohol complex. Propargyl alcochol exists in gauche form in the complex as well. In this study we have recorded pure rotational spectra of propargyl alcohol dimer between 4-13 GHz range.A total of 47 transitions, 24 a-type, 16 b-type and 7 c-type, have been observed and fitted with semi rigid rotor asymmetric top hamiltonian. The fitted rotational constants are: A = 2321.83323(47) MHz, B = 1150.47726(24) MHz and C = 1124.89000(20) MHz. The standard deviation for the fit is 2.5 kHz. The experimental rotational constants are very close to the structure predicted by ab-initio calculations in which two gauche-propargyl alcohol moieties are in three point contact stabilized by O-H...O, O-H...pi and C-H...pi interactions. Few transitions for duterated isotopologues of the dimer have also been observed and search for the remaining transitions is in progress. Details will be presented in the talk. E. Hirota,J. Mol. Spectrosc. 26 (1968) 335-350. J.C. Pearson, B.J. Drouin, J. Mol. Spectrosc. 234 (2005) 149-156. D. Mani, E. Arunan, ChemPhysChem 14 (2013) 754-763.

  17. Kinetics of DNA tile dimerization.

    PubMed

    Jiang, Shuoxing; Yan, Hao; Liu, Yan

    2014-06-24

    Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile-tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency.

  18. Kinetics of DNA Tile Dimerization

    PubMed Central

    2015-01-01

    Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile–tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency. PMID:24794259

  19. Physico-chemical properties of molten dimer ascorbate oxidase.

    PubMed

    Nicolai, Eleonora; Di Venere, Almerinda; Rosato, Nicola; Rossi, Antonello; Finazzi Agro', Alessandro; Mei, Giampiero

    2006-11-01

    The possible presence of dimeric unfolding intermediates might offer a clue to understanding the relationship between tertiary and quaternary structure formation in dimers. Ascorbate oxidase is a large dimeric enzyme that displays such an intermediate along its unfolding pathway. In this study the combined effect of high pressure and denaturing agents gave new insight on this intermediate and on the mechanism of its formation. The transition from native dimer to the dimeric intermediate is characterized by the release of copper ions forming the tri-nuclear copper center located at the interface between domain 2 and 3 of each subunit. This transition, which is pH-dependent, is accompanied by a decrease in volume, probably associated to electrostriction due to the loosening of intra-subunit electrostatic interactions. The dimeric species is present even at 3 x 10(8) Pa, providing evidence that mechanically or chemically induced unfolding lead to a similar intermediate state. Instead, dissociation occurs with an extremely large and negative volume change (DeltaV approximately -200 mL.mol(-1)) by pressurization in the presence of moderate amounts of denaturant. This volume change can be ascribed to the elimination of voids at the subunit interface. Furthermore, the combination of guanidine and high pressure uncovers the presence of a marginally stable (DeltaG approximately 2 kcal.mol(-1)) monomeric species (which was not observed in previous equilibrium unfolding measurements) that might be populated in the early folding steps of ascorbate oxidase. These findings provide new aspects of the protein folding pathway, further supporting the important role of quaternary interactions in the folding strategy of large dimeric enzymes.

  20. Theoretical studies on the dimerization of substituted paraphenylenediamine radical cations

    NASA Astrophysics Data System (ADS)

    Punyain, Kraiwan; Kelterer, Anne-Marie; Grampp, Günter

    2011-12-01

    Organic radical cations form dicationic dimers in solution, observed experimentally as diamagnetic species in temperature-dependent EPR and low temperature UV/Vis spectroscopy. Dimerization of paraphenylenediamine, N,N-dimethyl-paraphenylenediamine and 2,3,5,6-tetramethyl-paraphenylenediamine radical cation in ethanol/diethylether mixture was investigated theoretically according to geometry, energetics and UV/Vis spectroscopy. Density Functional Theory including dispersion correction describes stable dimers after geometry optimization with conductor-like screening model of solvation and inclusion of the counter-ion. Energy corrections were done on double-hybrid Density Functional Theory with perturbative second-order correlation (B2PLYP-D) including basis set superposition error (BSSE), and multireference Møller-Plesset second-order perturbation theory method (MRMP2) based on complete active space method (CASSCF(2,2)) single point calculation, respectively. All three dication π-dimers exhibit long multicenter π-bonds around 2.9 ± 0.1 Å with strongly interacting orbitals. Substitution with methyl groups does not influence the dimerization process substantially. Dispersion interaction and electrostatic attraction from counter-ion play an important role to stabilize the dication dimers in solution. Dispersion-corrected double hybrid functional B2PLYP-D and CASSCF(2,2) can describe the interaction energetics properly. Vertical excitations were computed with Tamm-Dancoff approximation for time-dependent Density Functional Theory (TDA-DFT) at the B3LYP level with the cc-pVTZ basis set including ethanol solvent molecules explicitly. A strong interaction of the counter-ion and the solvent ethanol with the monomeric species is observed, whereas in the dimers the strong interaction of both radical cation species is the dominating factor for the additional peak in UV/Vis spectra.

  1. Salt bridge residues between I-Ak dimer of dimers alpha-chains modulate antigen presentation.

    PubMed

    Yadati, S; Nydam, T; Demian, D; Wade, T K; Gabriel, J L; Barisas, B G; Wade, W F

    1999-03-15

    Class II dimers of dimers are predicted to have functional significance in antigen presentation. The putative contact amino acids of the I-Ak class II dimer of dimers have been identified by molecular modeling based on the DR1 crystal structure (Nydam et al., Int. Immunol. 10, 1237,1998). We have previously reported the role in antigen presentation of dimer of dimers contact amino acids located in the C-terminal domains of the alpha- and beta-chains of class II. Our calculations show that residues Ealpha89 and Ralpha145 in the alpha2-domain form an inter alpha-chain salt bridge between pairs of alphabeta-heterodimers. Other residues, Qalpha92 and Nalpha115, may be involved in close association in that part of the alpha-chain. We investigated the role of these amino acids on class II expression and antigen presentation. Class II composed of an Ealpha89K substituted alpha-chain paired with a wt beta-chain exhibited inhibited antigen presentation and expression of alpha-chain serologic epitopes. In contrast, mutation of Ralpha145E had less affect on antigen presentation and did not affect I-Ak serologic epitopes. Interchanging charges of the salt bridge residues by expressing both Ralpha145E and Ealpha89K on the same chain obviated the large negative effect of the Ealpha89K mutation on antigen presentation but not on the serologic epitopes. Our results are similar for those reported for mutation of DR3's inter-chain salt bridge with the exception that double mutants did not moderate the DR3 defect. Interestingly, the amino acids differences between I-A and DR change the location of the inter-chain salt bridges. In DR1 these residues are located at positions Ealpha88 and Kalpha111; in I-Ak these residues are located at position Ealpha89 and Ralpha145. Inter alpha-chain salt bridges are thus maintained in various class II molecules by amino acids located in different parts of the alpha2-domain. This conservation of structure suggests that considerable functional

  2. Water dimer equilibrium constant of saturated vapor

    NASA Astrophysics Data System (ADS)

    Malomuzh, N. P.; Mahlaichuk, V. N.; Khrapatyi, S. V.

    2014-08-01

    The value and temperature dependence of the dimerization constant for saturated water vapor are determined. A general expression that links the second virial coefficient and the dimerization constant is obtained. It is shown that the attraction between water monomers and dimers is fundamental, especially at T > 350 K. The range of application for the obtained results is determined.

  3. Highly stable tetrathiafulvalene radical dimers in [3]catenanes

    SciTech Connect

    Spruell, Jason M.; Coskun, Ali; Friedman, Douglas C.; Forgan, Ross S.; Sarjeant, Amy A.; Trabolsi, Ali; Fahrenbach, Albert C.; Barin, Gokhan; Paxton, Walter F.; Dey, Sanjeev K.; Olson, Mark A.; Benítez, Diego; Tkatchouk, Ekaterina; Colvin, Michael T.; Carmielli, Raanan; Caldwell, Stuart T.; Rosair, Georgina M.; Hewage, Shanika Gunatilaka; Duclairoir, Florence; Seymour, Jennifer L.; Slawin, Alexandra M.Z.; Goddard, III, William A.; Wasielewski, Michael R.; Cooke, Graeme; Stoddart, J. Fraser

    2010-12-03

    Two [3]catenane 'molecular flasks' have been designed to create stabilized, redox-controlled tetrathiafulvalene (TTF) dimers, enabling their spectrophotometric and structural properties to be probed in detail. The mechanically interlocked framework of the [3]catenanes creates the ideal arrangement and ultrahigh local concentration for the encircled TTF units to form stable dimers associated with their discrete oxidation states. These dimerization events represent an affinity umpolung, wherein the inversion in electronic affinity replaces the traditional TTF-bipyridinium interaction, which is over-ridden by stabilizing mixed-valence (TTF){sub 2}{sup {sm_bullet}+} and radical-cation (TTF{sup {sm_bullet}+}){sub 2} states inside the 'molecular flasks.' The experimental data, collected in the solid state as well as in solution under ambient conditions, together with supporting quantum mechanical calculations, are consistent with the formation of stabilized paramagnetic mixed-valence dimers, and then diamagnetic radical-cation dimers following subsequent one-electron oxidations of the [3]catenanes.

  4. Characterization of elements determining the dimerization properties of RelB and p50.

    PubMed Central

    Ryseck, R P; Novotny, J; Bravo, R

    1995-01-01

    Members of the Rel/NF-kappa B family of transcription factors share a region of approximately 300 amino acids which mediates dimerization and sequence-specific binding to DNA. Here we report a detailed characterization of the dimerization domain of RelB. The structural core sufficient to form stable Rel/NF-kappa B dimeric complexes consists of about 110 residues. The dimerization and DNA binding properties of more than 50 RelB mutants were analyzed by using p50 and p52 as partners. We present evidence that amino acids of a conserved element in the dimerization domain play a role in the recognition of a kappa B DNA target sequence. The analysis of hybrid molecules with dimerization domains containing different parts of p50 and RelB allowed us to identify some important structural elements determining homo- and heterodimerization properties. Furthermore, we were able to rescue the dimerization-defective mutant RelB-N287D by the introduction of a counteracting mutation intramolecularly (cis), and also intermolecularly (trans) by a mutation in the NF-kappa B dimerization partner p50. Correspondingly, a dimerization defective p50 mutant was effectively rescued by RelB-N287D. PMID:7760806

  5. Effects of dimerization on the structure and biological activity of antimicrobial peptide Ctx-Ha.

    PubMed

    Lorenzón, E N; Cespedes, G F; Vicente, E F; Nogueira, L G; Bauab, T M; Castro, M S; Cilli, E M

    2012-06-01

    It is well known that cationic antimicrobial peptides (cAMPs) are potential microbicidal agents for the increasing problem of antimicrobial resistance. However, the physicochemical properties of each peptide need to be optimized for clinical use. To evaluate the effects of dimerization on the structure and biological activity of the antimicrobial peptide Ctx-Ha, we have synthesized the monomeric and three dimeric (Lys-branched) forms of the Ctx-Ha peptide by solid-phase peptide synthesis using a combination of 9-fluorenylmethyloxycarbonyl (Fmoc) and t-butoxycarbonyl (Boc) chemical approaches. The antimicrobial activity assay showed that dimerization decreases the ability of the peptide to inhibit growth of bacteria or fungi; however, the dimeric analogs displayed a higher level of bactericidal activity. In addition, a dramatic increase (50 times) in hemolytic activity was achieved with these analogs. Permeabilization studies showed that the rate of carboxyfluorescein release was higher for the dimeric peptides than for the monomeric peptide, especially in vesicles that contained sphingomyelin. Despite different biological activities, the secondary structure and pore diameter were not significantly altered by dimerization. In contrast to the case for other dimeric cAMPs, we have shown that dimerization selectively decreases the antimicrobial activity of this peptide and increases the hemolytic activity. The results also show that the interaction between dimeric peptides and the cell wall could be responsible for the decrease of the antimicrobial activity of these peptides.

  6. Fiber optic D dimer biosensor

    DOEpatents

    Glass, R.S.; Grant, S.A.

    1999-08-17

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy. 4 figs.

  7. Fiber optic D dimer biosensor

    DOEpatents

    Glass, Robert S.; Grant, Sheila A.

    1999-01-01

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy.

  8. One-pot synthesis of high molecular weight synthetic heteroprotein dimers driven by charge complementarity electrostatic interactions.

    PubMed

    Hvasanov, David; Nam, Ekaterina V; Peterson, Joshua R; Pornsaksit, Dithepon; Wiedenmann, Jörg; Marquis, Christopher P; Thordarson, Pall

    2014-10-17

    Despite the importance of protein dimers and dimerization in biology, the formation of protein dimers through synthetic covalent chemistry has not found widespread use. In the case of maleimide-cysteine-based dimerization of proteins, we show here that when the proteins have the same charge, dimerization appears to be inherently difficult with yields around 1% or less, regardless of the nature of the spacer used or whether homo- or heteroprotein dimers are targeted. In contrast, if the proteins have opposing (complementary) charges, the formation of heteroprotein dimers proceeds much more readily, and in the case of one high molecular weight (>80 kDa) synthetic dimer between cytochrome c and bovine serum albumin, a 30% yield of the purified, isolated dimer was achieved. This represents at least a 30-fold increase in yield for protein dimers formed from proteins with complementary charges, compared to when the proteins have the same charge, under otherwise similar conditions. These results illustrate the role of ionic supramolecular interactions in controlling the reactivity of proteins toward bis-functionalized spacers. The strategy here for effective synthetic dimerization of proteins could be very useful for developing novel approaches to study the important role of protein-protein interactions in chemical biology.

  9. Micellisation and immunoreactivities of dimeric beta-caseins.

    PubMed

    Yousefi, Reza; Gaudin, Jean-Charles; Chobert, Jean-Marc; Pourpak, Zahra; Moin, Mostafa; Moosavi-Movahedi, Ali Akbar; Haertle, Thomas

    2009-12-01

    Bovine beta-casein (beta-CN) is a highly amphiphilic micellising phospho-protein showing chaperone-like activity in vitro. Recently, existence of multiple sequential epitopes on beta-CN polypeptide chain in both hydrophilic-polar (psi) and hydrophobic-apolar domains (phi) has been evidenced. In order to clarify specific contribution of polar and apolar domains in micellisation process and in shaping immunoreactivity of beta-CN, its dimeric/bi-amphiphilic "quasi palindromic" forms covalently connected by a disulfide bond linking either N-terminal (C4 beta-CND) or C-terminal domain (C208 beta-CND) were produced and studied. Depending on the C- or N-terminal position of inserted cysteine, each dimeric beta-CN contains one polar/apolar region at the centre and two external hydrophobic/hydrophilic ends. Consequently, such casein dimers have radically different polarities/hydrophobicities on their outside surfaces. Dynamic light scattering (DLS) measurements indicate that these dimeric casein molecules form micelles of different sizes depending on arrangement of polar fragments of the beta-CN mutants in their constrained dimers. Non-aggregated dimers have different hydrodynamic diameters that could be explained by their different geometries. Measurements of fluorescence showed more hydrophobic environment of Trp residues of C208 beta-CND, while in similar experimental conditions Trp residues of C4 beta-CND and native beta-CN were more exposed to the polar medium. Both fluorescence and DLS studies showed greater propensity for micellisation of the dimeric beta-CNs, suggesting that the factors inducing the formation of micelles are stronger in the bi-amphiphilic dimers. 1-anilino-naphthalene-8-sulfonate (ANS) binding studies showed different binding of ANS by these dimers as well as different exposition of ANS binding (hydrophobic) regions in the micellar states. The differences in fluorescence resonance energy transfer (FRET) profiles of C4 beta-CND and C208 beta-CND can

  10. Structural insights into lipid-dependent reversible dimerization of human GLTP

    SciTech Connect

    Samygina, Valeria R.; Ochoa-Lizarralde, Borja; Popov, Alexander N.; Cabo-Bilbao, Aintzane; Goni-de-Cerio, Felipe; Molotkovsky, Julian G.; Patel, Dinshaw J.; Brown, Rhoderick E.; Malinina, Lucy

    2013-04-01

    It is shown that dimerization is promoted by glycolipid binding to human GLTP. The importance of dimer flexibility in wild-type protein is manifested by point mutation that ‘locks’ the dimer while diversifying ligand/protein adaptations. Human glycolipid transfer protein (hsGLTP) forms the prototypical GLTP fold and is characterized by a broad transfer selectivity for glycosphingolipids (GSLs). The GLTP mutation D48V near the ‘portal entrance’ of the glycolipid binding site has recently been shown to enhance selectivity for sulfatides (SFs) containing a long acyl chain. Here, nine novel crystal structures of hsGLTP and the SF-selective mutant complexed with short-acyl-chain monoSF and diSF in different crystal forms are reported in order to elucidate the potential functional roles of lipid-mediated homodimerization. In all crystal forms, the hsGLTP–SF complexes displayed homodimeric structures supported by similarly organized intermolecular interactions. The dimerization interface always involved the lipid sphingosine chain, the protein C-terminus (C-end) and α-helices 6 and 2, but the D48V mutant displayed a ‘locked’ dimer conformation compared with the hinge-like flexibility of wild-type dimers. Differences in contact angles, areas and residues at the dimer interfaces in the ‘flexible’ and ‘locked’ dimers revealed a potentially important role of the dimeric structure in the C-end conformation of hsGLTP and in the precise positioning of the key residue of the glycolipid recognition centre, His140. ΔY207 and ΔC-end deletion mutants, in which the C-end is shifted or truncated, showed an almost complete loss of transfer activity. The new structural insights suggest that ligand-dependent reversible dimerization plays a role in the function of human GLTP.

  11. Crystal structure of an unknown solvate of {2,2′-[ethane-1,2-diylbis(nitrilo­methanylyl­idene)]diphenolato-κ4 O,N,N′,O′}(N-ferrocenylisonicotinamide-κN 1)cobalt(II): a CoII–salen complex that forms hydrogen-bonded dimers

    PubMed Central

    Brautigam, Bryan; Herholdt, Chelsea; Farnsworth, William; Brudi, Ellen; McDonald, Eric; Wu, Guang; Contakes, Stephen

    2015-01-01

    The title compound, [CoFe(C5H5)(C16H14N2O2)(C11H9N2O)], was prepared as an air-stable red–brown solid by mixing equimolar amounts of {2,2′-[ethane-1,2-diylbis(nitrilo­methanylyl­idene)]diphenolato}cobalt(II) and N-ferrocenylisonicotinamide in dry di­chloro­methane under nitro­gen and was characterized by ESI–MS, IR, and single-crystal X-ray diffraction. The structure at 100 K has triclinic (P-1) symmetry and indicates that the complex crystallizes as a mixture of λ and δ conformers. It exhibits the expected square pyramidal geometry about Co, and forms hydrogen-bonded dimers through amide N—H groups and phenolate O atoms on an adjacent mol­ecule. The involvement of only half of the salen ring structure in hydrogen-bonding inter­actions results in slight folding of the salen ring away from the pyridine coordination site in the δ conformer with an inter-salicyl­idene fold angle of 9.9 (7)°. In contrast, the λ conformer is nearly planar. The dimers pack into an open structure containing channels filled with highly disordered solvent mol­ecules. These solvent molecules’ contributions to the intensity data were removed with the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9–18] available in PLATON. PMID:26396858

  12. Dimeric α-Cobratoxin X-ray Structure

    PubMed Central

    Osipov, Alexey V.; Rucktooa, Prakash; Kasheverov, Igor E.; Filkin, Sergey Yu.; Starkov, Vladislav G.; Andreeva, Tatyana V.; Sixma, Titia K.; Bertrand, Daniel; Utkin, Yuri N.; Tsetlin, Victor I.

    2012-01-01

    In Naja kaouthia cobra venom, we have earlier discovered a covalent dimeric form of α-cobratoxin (αCT-αCT) with two intermolecular disulfides, but we could not determine their positions. Here, we report the αCT-αCT crystal structure at 1.94 Å where intermolecular disulfides are identified between Cys3 in one protomer and Cys20 of the second, and vice versa. All remaining intramolecular disulfides, including the additional bridge between Cys26 and Cys30 in the central loops II, have the same positions as in monomeric α-cobratoxin. The three-finger fold is essentially preserved in each protomer, but the arrangement of the αCT-αCT dimer differs from those of noncovalent crystallographic dimers of three-finger toxins (TFT) or from the κ-bungarotoxin solution structure. Selective reduction of Cys26-Cys30 in one protomer does not affect the activity against the α7 nicotinic acetylcholine receptor (nAChR), whereas its reduction in both protomers almost prevents α7 nAChR recognition. On the contrary, reduction of one or both Cys26-Cys30 disulfides in αCT-αCT considerably potentiates inhibition of the α3β2 nAChR by the toxin. The heteromeric dimer of α-cobratoxin and cytotoxin has an activity similar to that of αCT-αCT against the α7 nAChR and is more active against α3β2 nAChRs. Our results demonstrate that at least one Cys26-Cys30 disulfide in covalent TFT dimers, similar to the monomeric TFTs, is essential for their recognition by α7 nAChR, although it is less important for interaction of covalent TFT dimers with the α3β2 nAChR. PMID:22223648

  13. Dimeric RNA recognition regulates HIV-1 genome packaging.

    PubMed

    Nikolaitchik, Olga A; Dilley, Kari A; Fu, William; Gorelick, Robert J; Tai, S-H Sheldon; Soheilian, Ferri; Ptak, Roger G; Nagashima, Kunio; Pathak, Vinay K; Hu, Wei-Shau

    2013-03-01

    How retroviruses regulate the amount of RNA genome packaged into each virion has remained a long-standing question. Our previous study showed that most HIV-1 particles contain two copies of viral RNA, indicating that the number of genomes packaged is tightly regulated. In this report, we examine the mechanism that controls the number of RNA genomes encapsidated into HIV-1 particles. We hypothesize that HIV-1 regulates genome packaging by either the mass or copy number of the viral RNA. These two distinct mechanisms predict different outcomes when the genome size deviates significantly from that of wild type. Regulation by RNA mass would result in multiple copies of a small genome or one copy of a large genome being packaged, whereas regulation by copy number would result in two copies of a genome being packaged independent of size. To distinguish between these two hypotheses, we examined the packaging of viral RNA that was larger (≈17 kb) or smaller (≈3 kb) than that of wild-type HIV-1 (≈9 kb) and found that most particles packaged two copies of the viral genome regardless of whether they were 17 kb or 3 kb. Therefore, HIV-1 regulates RNA genome encapsidation not by the mass of RNA but by packaging two copies of RNA. To further explore the mechanism that governs this regulation, we examined the packaging of viral RNAs containing two packaging signals that can form intermolecular dimers or intramolecular dimers (self-dimers) and found that one self-dimer is packaged. Therefore, HIV-1 recognizes one dimeric RNA instead of two copies of RNA. Our findings reveal that dimeric RNA recognition is the key mechanism that regulates HIV-1 genome encapsidation and provide insights into a critical step in the generation of infectious viruses.

  14. Three-state kinetic folding mechanism of the H2A/H2B histone heterodimer: the N-terminal tails affect the transition state between a dimeric intermediate and the native dimer.

    PubMed

    Placek, Brandon J; Gloss, Lisa M

    2005-01-28

    The H2A/H2B heterodimer is a component of the nucleosome core particle, the fundamental repeating unit of chromatin in all eukaryotic cells. The kinetic folding mechanism for the H2A/H2B dimer has been determined from unfolding and refolding kinetics as a function of urea using stopped-flow, circular dichroism and fluorescence methods. The kinetic data are consistent with a three-state mechanism: two unfolded monomers associate to form a dimeric intermediate in the dead-time of the SF instrument (approximately 5 ms); this intermediate is then converted to the native dimer by a slower, first-order reaction. Analysis of the burst-phase amplitudes as a function of denaturant indicates that the dimeric kinetic intermediate possesses approximately 50% of the secondary structure and approximately 60% of the surface area burial of the native dimer. The stability of the dimeric intermediate is approximately 30% of that of the native dimer at the monomer concentrations employed in the SF experiments. Folding-to-unfolding double-jump experiments were performed to monitor the formation of the native dimer as a function of folding delay times. The double-jump data demonstrate that the dimeric intermediate is on-pathway and obligatory. Formation of a transient dimeric burst-phase intermediate has been observed in the kinetic mechanism of other intertwined, segment-swapped, alpha-helical, DNA-binding dimers, such as the H3-H4 histone dimer, Escherichia coli factor for inversion stimulation and E.coli Trp repressor. The common feature of a dimeric intermediate in these folding mechanisms suggests that this intermediate may accelerate protein folding, when compared to the folding of archael histones, which do not populate a transient dimeric species and fold more slowly.

  15. Correlation between plasma D-dimer levels and the severity of patients with chronic urticaria

    PubMed Central

    Triwongwaranat, Daranporn; Chularojanamontri, Leena; Pinkaew, Samruay

    2013-01-01

    Background Beside autoimmunity, coagulation pathway is also involved in the pathogenesis of chronic urticaria (CU). Previous studies showed that plasma D-dimer levels paralleled the severity of the disease. To date, there are no data concerning D-dimer level in Thai patients with CU. Objective This study aimed to find the relationship between plasma D-dimer levels and the disease severity of Thai CU patients. The secondary objective is to analyze plasma D-dimer level in each group of patients who performed autologous plasma skin testing (APST) and autologous serum skin testing (ASST). Methods We retrospectively reviewed case record forms of chronic idiopathic urticaria (CIU) patients aged at least 18 years in Skin Allergy Clinic, Siriraj Hospital Mahidol University, Bangkok, during June 2008 to June 2011. Results Of 120 patients, plasma D-dimer level was abnormal in 58 patients (48.3%). The study showed statistically significant positive correlation between disease severity and plasma D-dimer level (p < 0.05, r = 0.537). There was no statistically significant difference in plasma D-dimer level between APST positive and negative groups, and also between ASST positive and negative groups. In APST negative group, plasma D-dimer level was elevated in 29 patients (47.5%) and correlated with disease severity. Conclusion This study showed elevated plasma D-dimer levels in nearly half of Thai patients with CIU. There was a positive correlation between plasma D-dimer levels and the severity of disease activity. Investigation for plasma D-dimer level may be an alternative way to evaluate disease severity in patients with CIU. PMID:23667833

  16. Quantitative experimental determination of primer-dimer formation risk by free-solution conjugate electrophoresis.

    PubMed

    Desmarais, Samantha M; Leitner, Thomas; Barron, Annelise E

    2012-02-01

    DNA barcodes are short, unique ssDNA primers that "mark" individual biomolecules. To gain better understanding of biophysical parameters constraining primer-dimer formation between primers that incorporate barcode sequences, we have developed a capillary electrophoresis method that utilizes drag-tag-DNA conjugates to quantify dimerization risk between primer-barcode pairs. Results obtained with this unique free-solution conjugate electrophoresis approach are useful as quantitatively precise input data to parameterize computation models of dimerization risk. A set of fluorescently labeled, model primer-barcode conjugates were designed with complementary regions of differing lengths to quantify heterodimerization as a function of temperature. Primer-dimer cases comprised two 30-mer primers, one of which was covalently conjugated to a lab-made, chemically synthesized poly-N-methoxyethylglycine drag-tag, which reduced electrophoretic mobility of ssDNA to distinguish it from ds primer-dimers. The drag-tags also provided a shift in mobility for the dsDNA species, which allowed us to quantitate primer-dimer formation. In the experimental studies, pairs of oligonucleotide primer barcodes with fully or partially complementary sequences were annealed, and then separated by free-solution conjugate CE at different temperatures, to assess effects on primer-dimer formation. When less than 30 out of 30 base-pairs were bonded, dimerization was inversely correlated to temperature. Dimerization occurred when more than 15 consecutive base-pairs formed, yet non-consecutive base-pairs did not create stable dimers even when 20 out of 30 possible base-pairs bonded. The use of free-solution electrophoresis in combination with a peptoid drag-tag and different fluorophores enabled precise separation of short DNA fragments to establish a new mobility shift assay for detection of primer-dimer formation.

  17. Visualization of Myc/Max/Mad family dimers and the competition for dimerization in living cells.

    PubMed

    Grinberg, Asya V; Hu, Chang-Deng; Kerppola, Tom K

    2004-05-01

    Myc and Mad family proteins play opposing roles in the control of cell growth and proliferation. We have visualized the subcellular locations of complexes formed by Myc/Max/Mad family proteins using bimolecular fluorescence complementation (BiFC) analysis. Max was recruited to different subnuclear locations by interactions with Myc versus Mad family members. Complexes formed by Max with Mxi1, Mad3, or Mad4 were enriched in nuclear foci, whereas complexes formed with Myc were more uniformly distributed in the nucleoplasm. Mad4 was localized to the cytoplasm when it was expressed separately, and Mad4 was recruited to the nucleus through dimerization with Max. The cytoplasmic localization of Mad4 was determined by a CRM1-dependent nuclear export signal located near the amino terminus. We compared the relative efficiencies of complex formation among Myc, Max, and Mad family proteins in living cells using multicolor BiFC analysis. Max formed heterodimers with the basic helix-loop-helix leucine zipper (bHLHZIP) domain of Myc (bMyc) more efficiently than it formed homodimers. Replacement of two amino acid residues in the leucine zipper of Max reversed the relative efficiencies of homo- and heterodimerization in cells. Surprisingly, Mad3 formed complexes with Max less efficiently than bMyc, whereas Mad4 formed complexes with Max more efficiently than bMyc. The distinct subcellular locations and the differences between the efficiencies of dimerization with Max indicate that Mad3 and Mad4 are likely to modulate transcription activation by Myc at least in part through distinct mechanisms.

  18. Visualization of Myc/Max/Mad Family Dimers and the Competition for Dimerization in Living Cells†

    PubMed Central

    Grinberg, Asya V.; Hu, Chang-Deng; Kerppola, Tom K.

    2004-01-01

    Myc and Mad family proteins play opposing roles in the control of cell growth and proliferation. We have visualized the subcellular locations of complexes formed by Myc/Max/Mad family proteins using bimolecular fluorescence complementation (BiFC) analysis. Max was recruited to different subnuclear locations by interactions with Myc versus Mad family members. Complexes formed by Max with Mxi1, Mad3, or Mad4 were enriched in nuclear foci, whereas complexes formed with Myc were more uniformly distributed in the nucleoplasm. Mad4 was localized to the cytoplasm when it was expressed separately, and Mad4 was recruited to the nucleus through dimerization with Max. The cytoplasmic localization of Mad4 was determined by a CRM1-dependent nuclear export signal located near the amino terminus. We compared the relative efficiencies of complex formation among Myc, Max, and Mad family proteins in living cells using multicolor BiFC analysis. Max formed heterodimers with the basic helix-loop-helix leucine zipper (bHLHZIP) domain of Myc (bMyc) more efficiently than it formed homodimers. Replacement of two amino acid residues in the leucine zipper of Max reversed the relative efficiencies of homo- and heterodimerization in cells. Surprisingly, Mad3 formed complexes with Max less efficiently than bMyc, whereas Mad4 formed complexes with Max more efficiently than bMyc. The distinct subcellular locations and the differences between the efficiencies of dimerization with Max indicate that Mad3 and Mad4 are likely to modulate transcription activation by Myc at least in part through distinct mechanisms. PMID:15121849

  19. Measuring Membrane Protein Dimerization Equilibrium in Lipid Bilayers by Single-Molecule Fluorescence Microscopy.

    PubMed

    Chadda, R; Robertson, J L

    2016-01-01

    Dimerization of membrane protein interfaces occurs during membrane protein folding and cell receptor signaling. Here, we summarize a method that allows for measurement of equilibrium dimerization reactions of membrane proteins in lipid bilayers, by measuring the Poisson distribution of subunit capture into liposomes by single-molecule photobleaching analysis. This strategy is grounded in the fact that given a comparable labeling efficiency, monomeric or dimeric forms of a membrane protein will give rise to distinctly different photobleaching probability distributions. These methods have been used to verify the dimer stoichiometry of the Fluc F(-) ion channel and the dimerization equilibrium constant of the ClC-ec1 Cl(-)/H(+) antiporter in lipid bilayers. This approach can be applied to any membrane protein system provided it can be purified, fluorescently labeled in a quantitative manner, and verified to be correctly folded by functional assays, even if the structure is not yet known.

  20. Is Dimerization Required for the Catalytic Activity of Bacterial Biotin Carboxylase?

    SciTech Connect

    Shen,Y.; Chou, C.; Chang, G.; Tong, L.

    2006-01-01

    Acetyl-coenzyme A carboxylases (ACCs) have crucial roles in fatty acid metabolism. The biotin carboxylase (BC) subunit of Escherichia coli ACC is believed to be active only as a dimer, although the crystal structure shows that the active site of each monomer is 25 Angstroms from the dimer interface. We report here biochemical, biophysical, and structural characterizations of BC carrying single-site mutations in the dimer interface. Our studies demonstrate that two of the mutants, R19E and E23R, are monomeric in solution but have only a 3-fold loss in catalytic activity. The crystal structures of the E23R and F363A mutants show that they can still form the correct dimer at high concentrations. Our data suggest that dimerization is not an absolute requirement for the catalytic activity of the E. coli BC subunit, and we propose a new model for the molecular mechanism of action for BC in multisubunit and multidomain ACCs.

  1. Structure of an electric double layer containing a 2:2 valency dimer electrolyte

    SciTech Connect

    Silvestre-Alcantara, Whasington; Henderson, Douglas; Wu, Jianzhong; Kaja, Monika; Lamperski, Stanisław; Bhuiyan, Lutful Bari

    2014-12-05

    In this study, the structure of a planar electric double layer formed by a 2:2 valency dimer electrolyte in the vicinity of a uniformly charged planar hard electrode is investigated using density functional theory and Monte Carlo simulations. The dimer electrolyte consists of a mixture of charged divalent dimers and charged divalent monomers in a dielectric continuum. A dimer is constructed by two tangentially tethered rigid spheres, one of which is divalent and positively charged and the other neutral, whereas the monomer is a divalent and negatively charged rigid sphere. The density functional theory reproduces well the simulation results for (i) the singlet distributions of the various ion species with respect to the electrode, and (ii) the mean electrostatic potential. Lastly, comparison with earlier results for a 2:1/1:2 dimer electrolyte shows that the double layer structure is similar when the counterion has the same valency.

  2. Structure of an electric double layer containing a 2:2 valency dimer electrolyte

    DOE PAGES

    Silvestre-Alcantara, Whasington; Henderson, Douglas; Wu, Jianzhong; ...

    2014-12-05

    In this study, the structure of a planar electric double layer formed by a 2:2 valency dimer electrolyte in the vicinity of a uniformly charged planar hard electrode is investigated using density functional theory and Monte Carlo simulations. The dimer electrolyte consists of a mixture of charged divalent dimers and charged divalent monomers in a dielectric continuum. A dimer is constructed by two tangentially tethered rigid spheres, one of which is divalent and positively charged and the other neutral, whereas the monomer is a divalent and negatively charged rigid sphere. The density functional theory reproduces well the simulation results formore » (i) the singlet distributions of the various ion species with respect to the electrode, and (ii) the mean electrostatic potential. Lastly, comparison with earlier results for a 2:1/1:2 dimer electrolyte shows that the double layer structure is similar when the counterion has the same valency.« less

  3. Microwave Measurements of Maleimide and its Doubly Hydrogen Bonded Dimer with Formic ACID*

    NASA Astrophysics Data System (ADS)

    Pejlovas, Aaron M.; Kang, Lu; Kukolich, Stephen G.

    2016-06-01

    The microwave spectra were measured for the maleimide monomer and the maleimide-formic acid doubly hydrogen bonded dimer using a pulsed-beam Fourier transform microwave spectrometer. Many previously studied doubly hydrogen bonded dimers are formed between oxygen containing species, so it is important to also characterize and study other dimers containing nitrogen, as hydrogen bonding interactions with nitrogen are found in biological systems such as in DNA. The transition state of the dimer does not exhibit C_2_V symmetry, so the tunneling motion was not expected to be observed based on the symmetry, but it would be very important to also observe the tunneling process for an asymmetric dimer. Single-line b-type transitions were observed, so the tunneling motion was not observed in our microwave spectra. The hydrogen bond lengths were determined using a nonlinear least squares fitting program. *Supported by the NSF CHE-1057796

  4. Dimerization of Matrix Protein Is Required for Budding of Respiratory Syncytial Virus

    PubMed Central

    Förster, Andreas; Maertens, Goedele N.; Farrell, Paul J.

    2015-01-01

    ABSTRACT Respiratory syncytial virus (RSV) infects epithelial cells of the respiratory tract and is a major cause of bronchiolitis and pneumonia in children and the elderly. The virus assembles and buds through the plasma membrane, forming elongated membrane filaments, but details of how this happens remain obscure. Oligomerization of the matrix protein (M) is a key step in the process of assembly and infectious virus production. In addition, it was suggested to affect the conformation of the fusion protein, the major current target for RSV antivirals, in the mature virus. The structure and assembly of M are thus key parameters in the RSV antiviral development strategy. The structure of RSV M was previously published as a monomer. Other paramyxovirus M proteins have been shown to dimerize, and biochemical data suggest that RSV M also dimerizes. Here, using size exclusion chromatography-multiangle laser light scattering, we show that the protein is dimeric in solution. We also crystallized M in two crystal forms and show that it assembles into equivalent dimers in both lattices. Dimerization interface mutations destabilize the M dimer in vitro. To assess the biological relevance of dimerization, we used confocal imaging to show that dimerization interface mutants of M fail to assemble into viral filaments on the plasma membrane. Additionally, budding and release of virus-like particles are prevented in M mutants that fail to form filaments. Importantly, we show that M is biologically active as a dimer and that the switch from M dimers to higher-order oligomers triggers viral filament assembly and virus production. IMPORTANCE Human respiratory syncytial virus (RSV) is the most frequent cause of infantile bronchiolitis and pneumonia. The enormous burden of RSV makes it a major unmet target for a vaccine and antiviral drug therapy. Oligomerization of the matrix protein is a key step in the process of assembly and production of infectious virus, but the molecular

  5. Dimerization of postsynaptic neuroligin drives synaptic assembly via transsynaptic clustering of neurexin.

    PubMed

    Shipman, Seth L; Nicoll, Roger A

    2012-11-20

    The transsynaptic complex of neuroligin (NLGN) and neurexin forms a physical connection between pre- and postsynaptic neurons that occurs early in the course of new synapse assembly. Both neuroligin and neurexin have, indeed, been proposed to exhibit active, instructive roles in the formation of synapses. However, the process by which these instructive roles play out during synaptogenesis is not well understood. Here, we examine one aspect of postsynaptic neuroligin with regard to its synaptogenic properties: its basal state as a constitutive dimer. We show that dimerization is required for the synaptogenic properties of neuroligin and likely serves to induce presynaptic differentiation via a transsynaptic clustering of neurexin. Further, we introduce chemically inducible, exogenous dimerization domains to the neuroligin molecule, effectively bestowing chemical control of neuroligin dimerization. This allows us to identify the acute requirements of neuroligin dimerization by chemically manipulating the monomeric-to-dimeric conversion of neuroligin. Based on the results of the inducible dimerization experiments, we propose a model in which dimerized neuroligin induces the mechanical clustering of presynaptic molecules as part of a requisite step in the coordinated assembly of a chemical synapse.

  6. Cold-active alkaline phosphatase is irreversibly transformed into an inactive dimer by low urea concentrations.

    PubMed

    Hjörleifsson, Jens Guðmundur; Ásgeirsson, Bjarni

    2016-07-01

    Alkaline phosphatase is a homodimeric metallo-hydrolase where both Zn(2+) and Mg(2+) are important for catalysis and stability. Cold-adapted alkaline phosphatase variants have high activity at low temperatures and lower thermal stability compared with variants from mesophilic hosts. The instability, and thus inactivation, could be due to loose association of the dimers and/or loosely bound Mg(2)(+) in the active site, but this has not been studied in detail for the cold-adapted variants. Here, we focus on using the intrinsic fluorescence of Trp in alkaline phosphatase from the marine bacterium Vibrio splendidus (VAP) to probe for dimerization. Trp→Phe substitutions showed that two out of the five native Trp residues contributed mostly to the fluorescence emission. One residue, 15Å away from the active site (W460) and highly solvent excluded, was phosphorescent and had a distant role in substrate binding. An additional Trp residue was introduced to the dimer interface to act as a possible probe for dimerization. Urea denaturation curves indicated that an inactive dimer intermediate, structurally equivalent to the native state, was formed before dimer dissociation took place. This is the first example of the transition of a native dimer to an inactive dimer intermediate for alkaline phosphatase without using mutagenesis, ligands, or competitive inhibition.

  7. Synchronized oscillations of dimers in biphasic charged fd-virus suspensions

    NASA Astrophysics Data System (ADS)

    Kang, K.; Piao, S. H.; Choi, H. J.

    2016-08-01

    Micron-sized colloidal spheres that are dispersed in an isotropic-nematic biphasic host suspension of charged rods (fd-virus particles) are shown to spontaneously form dimers, which exhibit a synchronized oscillatory motion. Dimer formation is not observed in the monophase of isotropic and nematic suspensions. The synchronized oscillations of dimers are connected to the inhomogeneous state of the host suspension of charged rods (fd viruses) where nematic domains are in coexistence with isotropic regions. The synchronization of oscillations occurs in bulk states, in the absence of an external field. With a low field strength of an applied electric field, the synchronization is rather reduced, but it recovers again when the field is turned off. In this Rapid Communication, we report this observation as an example of the strange attractor, occurring in the mixture of PS (polystyrene) dimers in an isotropic-nematic coexistence biphasic fd-virus network. Furthermore, we highlight that the synchronization of PS-dimer oscillations is the result of a global bifurcation diagram, driven by a delicate balance between the short-attractive "twisted" interaction of PS dimers and long-ranged electrostatic repulsive interactions of charged fd rods. The interest is then in the local enhancement of "twist-nematic" elasticity in reorientation of the dimer oscillations. An analysis of image-time correlations is provided with the data movies and Fourier transforms of averaged orientations for the synchronized oscillations of dimers in the biphasic I -N coexistence concentration of charged fd-virus suspensions.

  8. D-Dimer elevation and adverse outcomes.

    PubMed

    Halaby, Rim; Popma, Christopher J; Cohen, Ander; Chi, Gerald; Zacarkim, Marcelo Rodrigues; Romero, Gonzalo; Goldhaber, Samuel Z; Hull, Russell; Hernandez, Adrian; Mentz, Robert; Harrington, Robert; Lip, Gregory; Peacock, Frank; Welker, James; Martin-Loeches, Ignacio; Daaboul, Yazan; Korjian, Serge; Gibson, C Michael

    2015-01-01

    D-Dimer is a biomarker of fibrin formation and degradation. While a D-dimer within normal limits is used to rule out the diagnosis of deep venous thrombosis and pulmonary embolism among patients with a low clinical probability of venous thromboembolism (VTE), the prognostic association of an elevated D-dimer with adverse outcomes has received far less emphasis. An elevated D-dimer is independently associated with an increased risk for incident VTE, recurrent VTE, and mortality. An elevated D-dimer is an independent correlate of increased mortality and subsequent VTE across a broad variety of disease states. Therefore, medically ill subjects in whom the D-dimer is elevated constitute a high risk subgroup in which the prospective evaluation of the efficacy and safety of antithrombotic therapy is warranted.

  9. Solitary waves in dimer binary collision model

    NASA Astrophysics Data System (ADS)

    Ahsan, Zaid; Jayaprakash, K. R.

    2017-01-01

    Solitary wave propagation in nonlinear diatomic (dimer) chains is a very interesting topic of research in the study of nonlinear lattices. Such waves were recently found to be supported by the essentially nonlinear granular lattice and Toda lattice. An interesting aspect of this discovery is attributed to the realization of a spectrum of the mass ratio (the only system parameter governing the dynamics) that supports the propagation of such waves corresponding to the considered interaction potential. The objective of this exposition is to explore solitary wave propagation in the dimer binary collision (BC) model. Interestingly, the dimer BC model supports solitary wave propagation at a discrete spectrum of mass ratios similar to those observed in granular and Toda dimers. Further, we report a qualitative and one-to-one correspondence between the spectrum of the mass ratio corresponding to the dimer BC model and those corresponding to granular and Toda dimer chains.

  10. Dimerization of Human Growth Hormone by Zinc

    NASA Astrophysics Data System (ADS)

    Cunningham, Brian C.; Mulkerrin, Michael G.; Wells, James A.

    1991-08-01

    Size-exclusion chromatography and sedimentation equilibrium studies demonstrated that zinc ion (Zn2+) induced the dimerization of human growth hormone (hGH). Scatchard analysis of 65Zn2+ binding to hGH showed that two Zn2+ ions associate per dimer of hGH in a cooperative fashion. Cobalt (II) can substitute for Zn2+ in the hormone dimer and gives a visible spectrum characteristic of cobalt coordinated in a tetrahedral fashion by oxygen- and nitrogen-containing ligands. Replacement of potential Zn2+ ligands (His18, His21, and Glu174) in hGH with alanine weakened both Zn2+ binding and hGH dimer formation. The Zn2+-hGH dimer was more stable than monomeric hGH to denaturation in guanidine-HCl. Formation of a Zn2+-hGH dimeric complex may be important for storage of hGH in secretory granules.

  11. Monomer-dimer problem on some networks

    NASA Astrophysics Data System (ADS)

    Wu, Ruijuan; Yan, Weigen

    2016-09-01

    Zhang et al. (2012) obtained the exact formula for the number of all possible monomer-dimer arrangements and the asymptotic growth constant on a scale-free small-world network. In this note, we generalize this result and obtain the exact solution on the monomer-dimer model on many networks. Particularly, we prove that these networks have the same asymptotic growth constant of the number of monomer-dimer arrangements.

  12. Thermalization of a dimerized antiferromagnetic spin chain.

    PubMed

    Konstantinidis, N P

    2016-01-20

    Thermalization is investigated for the one-dimensional anisotropic antiferromagnetic Heisenberg model with dimerized nearest-neighbor interactions that break integrability. For this purpose the time evolution of local operator expectation values after an interacting quench is calculated directly with the Chebyshev polynomial expansion, and the deviation of the diagonal from the canonical thermal ensemble value is calculated for increasing system size for these operators. The spatial and spin symmetries of the Hamiltonian are taken into account to divide it into symmetry subsectors. The rate of thermalization is found to weaken with the dimerization parameter as the Hamiltonian evolves between two integrable limits, the non-dimerized and the fully dimerized where the chain breaks up into isolated dimers. This conclusion is supported by the distribution of the local operator off-diagonal elements between the eigenstates of the Hamiltonian with respect to their energy difference, which determines the strength of temporal fluctuations. The off-diagonal elements have a low-energy peak for small dimerization which facilitates thermalization, and originates in the reduction of spatial symmetry with respect to the non-dimerized limit. For increasing dimerization their distribution changes and develops a single low-energy maximum that relates to the fully dimerized limit and slows down thermalization.

  13. Transporting testosterone and its dimers by serum proteins.

    PubMed

    Chanphai, P; Vesper, A R; Bekale, L; Bérubé, G; Tajmir-Riahi, H A

    2015-12-01

    A substantial part of steroids is bound to serum proteins in vivo. We report the association of testosterone and it aliphatic dimer (alip) and aromatic dimer (arom) with human serum albumin (HSA) and bovine serum albumin (BSA) in aqueous solution at physiological pH. Multiple spectroscopic methods, transmission electron microscopy (TEM) and molecular modeling were used to characterize steroid-protein binding and protein aggregation process. Spectroscopic analysis showed that steroids bind protein via hydrophobic, hydrophilic and H-bonding interactions. HSA forms more stable complexes than BSA. The binding affinity of steroid-protein adducts is testosterone>dimer-aromatic>dimer-aliphatic. Transmission electron microscopy showed major changes in protein morphology as steroid-protein complexation occurred with increase in the diameter of the protein aggregate indicating encapsulation of steroids by serum proteins. Modeling showed the presence of H-bonding stabilized testosterone-protein complexes with the free binding energy of -12.95 for HSA and -11.55 kcal/mol for BSA, indicating that the interaction process is spontaneous at room temperature. Steroid complexation induced more perturbations of BSA conformation than HSA.

  14. Centrosymmetric dimer of quinuclidine betaine and squaric acid complex

    NASA Astrophysics Data System (ADS)

    Dega-Szafran, Z.; Katrusiak, A.; Szafran, M.

    2012-12-01

    The complex of squaric acid (3,4-dihydroxy-3-cyclobuten-1,2-dion, H2SQ) with quinuclidine betaine (1-carboxymethyl-1-azabicyclo[2.2.2]octane inner salt, QNB), 1, has been characterized by single-crystal X-ray analysis, FTIR and NMR spectroscopies and by DFT calculations. In the crystal of 1, monoclinic space group P21/n, one proton from H2SQ is transferred to QNB. QNBH+ and HSQ- are linked together by a Osbnd H⋯O hydrogen bond of 2.553(2) Å. Two such QNBH+·HSQ- complexes form a centrosymmetric dimer bridged by two Osbnd H⋯O bonds of 2.536(2) Å. The FTIR spectrum is consistent with the X-ray results. The structures of monomer QNBH+·HSQ- (1a) and dimer [QNB·H2SQ]2 (2) have been optimized at the B3LYP/6-311++G(d,p) level of theory. Isolated dimer 2 optimized back to a molecular aggregate of H2SQ and QNB. The calculated frequencies for the optimized structure of dimer 2 have been used to explain the frequencies of the experimental FTIR spectrum. The interpretation of 1H and 13C NMR spectra has been based on the calculated GIAO/B3LYP/6-311++G(d,p) magnetic isotropic shielding constants for monomer 1a.

  15. Dynamic Cholesterol-Conditioned Dimerization of the G Protein Coupled Chemokine Receptor Type 4

    PubMed Central

    Kranz, Franziska

    2016-01-01

    G protein coupled receptors (GPCRs) allow for the transmission of signals across biological membranes. For a number of GPCRs, this signaling was shown to be coupled to prior dimerization of the receptor. The chemokine receptor type 4 (CXCR4) was reported before to form dimers and their functionality was shown to depend on membrane cholesterol. Here, we address the dimerization pattern of CXCR4 in pure phospholipid bilayers and in cholesterol-rich membranes. Using ensembles of molecular dynamics simulations, we show that CXCR4 dimerizes promiscuously in phospholipid membranes. Addition of cholesterol dramatically affects the dimerization pattern: cholesterol binding largely abolishes the preferred dimer motif observed for pure phospholipid bilayers formed mainly by transmembrane helices 1 and 7 (TM1/TM5-7) at the dimer interface. In turn, the symmetric TM3,4/TM3,4 interface is enabled first by intercalating cholesterol molecules. These data provide a molecular basis for the modulation of GPCR activity by its lipid environment. PMID:27812115

  16. Dimer motion on a periodic substrate: spontaneous symmetry breaking and absolute negative mobility.

    PubMed

    Speer, David; Eichhorn, Ralf; Evstigneev, Mykhaylo; Reimann, Peter

    2012-06-01

    We consider two coupled particles moving along a periodic substrate potential with negligible inertia effects (overdamped limit). Even when the particles are identical and the substrate spatially symmetric, a sinusoidal external driving of appropriate amplitude and frequency may lead to spontaneous symmetry breaking in the form of a permanent directed motion of the dimer. Thermal noise restores ergodicity and thus zero net velocity, but entails arbitrarily fast diffusion of the dimer for sufficiently weak noise. Moreover, upon application of a static bias force, the dimer exhibits a motion opposite to that force (absolute negative mobility). The key requirement for all these effects is a nonconvex interaction potential of the two particles.

  17. Determination of pyrimidine dimers in Escherichia coli and Cryptosporidium parvum during UV light inactivation, photoreactivation, and dark repair.

    PubMed

    Oguma, K; Katayama, H; Mitani, H; Morita, S; Hirata, T; Ohgaki, S

    2001-10-01

    UV inactivation, photoreactivation, and dark repair of Escherichia coli and Cryptosporidium parvum were investigated with the endonuclease sensitive site (ESS) assay, which can determine UV-induced pyrimidine dimers in the genomic DNA of microorganisms. In a 99.9% inactivation of E. coli, high correlation was observed between the dose of UV irradiation and the number of pyrimidine dimers induced in the DNA of E. coli. The colony-forming ability of E. coli also correlated highly with the number of pyrimidine dimers in the DNA, indicating that the ESS assay is comparable to the method conventionally used to measure colony-forming ability. When E. coli were exposed to fluorescent light after a 99.9% inactivation by UV irradiation, UV-induced pyrimidine dimers in the DNA were continuously repaired and the colony-forming ability recovered gradually. When kept in darkness after the UV inactivation, however, E. coli showed neither repair of pyrimidine dimers nor recovery of colony-forming ability. When C. parvum were exposed to fluorescent light after UV inactivation, UV-induced pyrimidine dimers in the DNA were continuously repaired, while no recovery of animal infectivity was observed. When kept in darkness after UV inactivation, C. parvum also showed no recovery of infectivity in spite of the repair of pyrimidine dimers. It was suggested, therefore, that the infectivity of C. parvum would not recover either by photoreactivation or by dark repair even after the repair of pyrimidine dimers in the genomic DNA.

  18. New Insight into Secreted Ribonuclease Structure: Binase Is a Natural Dimer

    PubMed Central

    Dudkina, Elena; Kayumov, Airat; Ulyanova, Vera; Ilinskaya, Olga

    2014-01-01

    The biological effects of ribonucleases (RNases), such as the control of the blood vessels growth, the toxicity towards tumour cells and antiviral activity, require a detailed explanation. One of the most intriguing properties of RNases which can contribute to their biological effects is the ability to form dimers, which facilitates efficient RNA hydrolysis and the evasion of ribonuclease inhibitor. Dimeric forms of microbial RNase binase secreted by Bacillus pumilus (former B. intermedius) have only been found in crystals to date. Our study is the first report directly confirming the existence of binase dimers in solution and under natural conditions of enzyme biosynthesis and secretion by bacilli. Using different variants of gel electrophoresis, immunoblotting, size-exclusion chromatography and mass-spectrometry, we revealed that binase is a stable natural dimer with high catalytic activity. PMID:25551440

  19. Potassium Hexacyanoferrate (III)-Catalyzed Dimerization of Hydroxystilbene: Biomimetic Synthesis of Indane Stilbene Dimers.

    PubMed

    Xie, Jing-Shan; Wen, Jin; Wang, Xian-Fen; Zhang, Jian-Qiao; Zhang, Ji-Fa; Kang, Yu-Long; Hui, You-Wei; Zheng, Wen-Sheng; Yao, Chun-Suo

    2015-12-18

    Using potassium hexacyanoferrate (III)-sodium acetate as oxidant, the oxidative coupling reaction of isorhapontigenin and resveratrol in aqueous acetone resulted in the isolation of three new indane dimers 4, 6, and 7, together with six known stilbene dimers. Indane dimer 5 was obtained for the first time by direct transformation from isorhapontigenin. The structures and relative configurations of the dimers were elucidated using spectral analysis, and their possible formation mechanisms were discussed. The results indicate that this reaction could be used as a convenient method for the semi-synthesis of indane dimers because of the mild conditions and simple reaction products.

  20. Interaction be