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Mint3 is dispensable for pancreatic and kidney functions in mice. Biochem Biophys Rep 2020; 24:100872. [PMID: 33319072 PMCID: PMC7725678 DOI: 10.1016/j.bbrep.2020.100872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 11/06/2020] [Accepted: 11/24/2020] [Indexed: 02/07/2023] Open
Abstract
Munc-18 interacting protein 3 (Mint3) is an activator of hypoxia-inducible factor-1 in cancer cells, macrophages, and cancer-associated fibroblasts under pathological conditions. However, exactly which cells highly express Mint3 in vivo and whether Mint3 depletion affects their physiological functions remain unclear. Here, we surveyed mouse tissues for specific expression of Mint3 by comparing Mint3 expression in wild-type and Mint3-knockout mice. Interestingly, immunohistochemical analyses revealed that Mint3 was highly expressed in islet cells of the pancreas, distal tubular epithelia of the kidney, choroid plexus ependymal cells of the cerebrum, medullary cells of the adrenal gland, and epithelial cells of the seminal gland. We also studied whether Mint3 depletion affects the physiological functions of the islets and kidneys. Mint3-knockout mice did not show any abnormalities in glucose-tolerance and urine-biochemical tests, indicating that Mint3 depletion was compensated for in these organs. Thus, loss of Mint3 might be compensated in the islets and kidneys under physiological conditions in mice. Specific expression of Mint3 in mouse tissues is surveyed. Mint3 is highly expressed in islet cells of the pancreas. Mint3 is highly expressed in distal tubular epithelia of the kidney. Mint3 KO mice do not show any abnormalities in glucose-tolerance tests. Mint3 KO mice do not show any abnormalities in urine-biochemical tests.
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2
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Exploratory locomotion, a predictor of addiction vulnerability, is oligogenic in rats selected for this phenotype. Proc Natl Acad Sci U S A 2019; 116:13107-13115. [PMID: 31182603 PMCID: PMC6600920 DOI: 10.1073/pnas.1820410116] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Artificially selected model organisms can reveal hidden features of the genetic architecture of the complex disorders that they model. Addictions are disease phenotypes caused by different intermediate phenotypes and pathways and thereby are potentially highly polygenic. High responder (bHR) and low responder (bLR) rat lines have been selectively bred (b) for exploratory locomotion (EL), a behavioral phenotype correlated with novelty-seeking, impulsive response to reward, and vulnerability to addiction, and is inversely correlated with spontaneous anxiety and depression-like behaviors. The rapid response to selection indicates loci of large effect for EL. Using exome sequencing of HR and LR rats, we identified alleles in gene-coding regions that segregate between the two lines. Quantitative trait locus (QTL) analysis in F2 rats derived from a bHR × bLR intercross confirmed that these regions harbored genes affecting EL. The combined effects of the seven genome-wide significant QTLs accounted for approximately one-third of the total variance in EL, and two-thirds of the variance attributable to genetic factors, consistent with an oligogenic architecture of EL estimated both from the phenotypic distribution of F2 animals and rapid response to selection. Genetic association in humans linked APBA2, the ortholog of the gene at the center of the strongest QTL, with substance use disorders and related behavioral phenotypes. Our finding is also convergent with molecular and animal behavioral studies implicating Apba2 in locomotion. These results provide multilevel evidence for genes/loci influencing EL. They shed light on the genetic architecture of oligogenicity in animals artificially selected for a phenotype modeling a more complex disorder in humans.
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Jones KA, Eng AG, Raval P, Srivastava DP, Penzes P. Scaffold protein X11α interacts with kalirin-7 in dendrites and recruits it to Golgi outposts. J Biol Chem 2014; 289:35517-29. [PMID: 25378388 PMCID: PMC4271236 DOI: 10.1074/jbc.m114.587709] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Pyramidal neurons in the mammalian forebrain receive their synaptic inputs through their dendritic trees, and dendritic spines are the sites of most excitatory synapses. Dendritic spine structure is important for brain development and plasticity. Kalirin-7 is a guanine nucleotide-exchange factor for the small GTPase Rac1 and is a critical regulator of dendritic spine remodeling. The subcellular localization of kalirin-7 is thought to be important for regulating its function in neurons. A yeast two-hybrid screen has identified the adaptor protein X11α as an interacting partner of kalirin-7. Here, we show that kalirin-7 and X11α form a complex in the brain, and this interaction is mediated by the C terminus of kalirin-7. Kalirin-7 and X11α co-localize at excitatory synapses in cultured cortical neurons. Using time-lapse imaging of fluorescence recovery after photobleaching, we show that X11α is present in a mobile fraction of the postsynaptic density. X11α also localizes to Golgi outposts in dendrites, and its overexpression induces the removal of kalirin-7 from spines and accumulation of kalirin-7 in Golgi outposts. In addition, neurons overexpressing X11α displayed thinner spines. These data support a novel mechanism of regulation of kalirin-7 localization and function in dendrites, providing insight into signaling pathways underlying neuronal plasticity. Dissecting the molecular mechanisms of synaptic structural plasticity will improve our understanding of neuropsychiatric and neurodegenerative disorders, as kalirin-7 has been associated with schizophrenia and Alzheimer disease.
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Affiliation(s)
| | - Andrew G Eng
- the Interdepartmental Neuroscience Graduate Program, Northwestern University, Chicago, Illinois 60611, and
| | - Pooja Raval
- the Department of Neuroscience and Centre for the Cellular Basis of Behaviour, The James Black Centre, Institute of Psychiatry, King's College London, London SE5 9NU, United Kingdom
| | - Deepak P Srivastava
- From the Departments of Physiology and the Department of Neuroscience and Centre for the Cellular Basis of Behaviour, The James Black Centre, Institute of Psychiatry, King's College London, London SE5 9NU, United Kingdom
| | - Peter Penzes
- From the Departments of Physiology and Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611,
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Waltereit R, Banaschewski T, Meyer-Lindenberg A, Poustka L. Interaction of neurodevelopmental pathways and synaptic plasticity in mental retardation, autism spectrum disorder and schizophrenia: implications for psychiatry. World J Biol Psychiatry 2014; 15:507-16. [PMID: 24079538 DOI: 10.3109/15622975.2013.838641] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES Schizophrenia (SCZ), autism spectrum disorder (ASD) and mental retardation (MR) are psychiatric disorders with high heritability. They differ in their clinical presentation and in their time course of major symptoms, which predominantly occurs for MR and ASD during childhood and for SCZ during young adult age. Recent findings with focus on the developmental neurobiology of these disorders emphasize shared mechanisms of common origin. These findings propose a continuum of genetic risk factors impacting on synaptic plasticity with MR causing impairments in global cognitive abilities, ASD in social cognition and SCZ in both global and social cognition. METHODS We assess here the historical developments that led to the current disease concepts of the three disorders. We then analyse, based on the functions of genes mutated in two or three of the disorders, selected mechanisms shared in neurodevelopmental pathways and synaptic plasticity. RESULTS The analysis of the psychopathological constructs supports the existence of three distinct clinical entities but also elaborates important associations. Similarly, there are common mechanisms especially in global and social cognition. CONCLUSIONS We discuss implications from this integrated view on MR, ASD and SCZ for child & adolescent and adult psychiatry in pathophysiology and research perspectives.
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Affiliation(s)
- Robert Waltereit
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health and University of Heidelberg, Mannheim Medical Faculty , Mannheim , Germany
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5
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Abstract
Overexpression of neuronal adaptor protein X11β has been shown to decrease the production of amyloid-β, a toxic peptide deposited in Alzheimer's disease brains. Therefore, manipulation of the X11β level may represent a potential therapeutic strategy for Alzheimer's disease. As X11β expression can be regulated at the transcription level, we determined the genomic organization and the promoter of the human X11β gene, amyloid β A4 precursor protein-binding family A member 2 (APBA2). By RNA ligase-mediated rapid amplification of cDNA ends, a single APBA2 transcription start site and the complete sequence of exon 1 were identified. The APBA2 promoter was located upstream of exon 1 and was more active in neurons. The core promoter contains several CpG dinucleotides, and was strongly suppressed by DNA methylation. In addition, mutagenesis analysis revealed a putative Pax5-binding site within the promoter. Together, APBA2 contains a potent neuronal promoter whose activity may be regulated by DNA methylation and Pax5.
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6
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Chai KH, McLoughlin DM, Chan TF, Chan HYE, Lau KF. Genomic organization and promoter cloning of the human X11α gene APBA1. DNA Cell Biol 2011; 31:651-9. [PMID: 22136355 DOI: 10.1089/dna.2011.1447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
X11α is a brain specific multi-modular protein that interacts with the Alzheimer's disease amyloid precursor protein (APP). Aggregation of amyloid-β peptide (Aβ), an APP cleavage product, is believed to be central to the pathogenesis of Alzheimer's disease. Recently, overexpression of X11α has been shown to reduce Aβ generation and to ameliorate memory deficit in a transgenic mouse model of Alzheimer's disease. Therefore, manipulating the expression level of X11α may provide a novel route for the treatment of Alzheimer's disease. Human X11α is encoded by the gene APBA1. As evidence suggests that X11α expression can be regulated at transcription level, we have determined the gene structure and cloned the promoter of APBA1. APBA1 spans over 244 kb on chromosome 9 and is composed of 13 exons and has multiple transcription start sites. A putative APBA1 promoter has been identified upstream of exon 1 and functional analysis revealed that this is highly active in neurons. By deletion analysis, the minimal promoter was found to be located between -224 and +14, a GC-rich region that contains a functional Sp3 binding site. In neurons, overexpression of Sp3 stimulates the APBA1 promoter while an Sp3 inhibitor suppresses the promoter activity. Moreover, inhibition of Sp3 reduces endogenous X11α expression and promotes the generation of Aβ. Our findings reveal that Sp3 play an essential role in APBA1 transcription.
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Affiliation(s)
- Ka-Ho Chai
- Biochemistry Program, School Life Sciences, The Chinese University of Hong Kong , Shatin, New Territories, Hong Kong SAR
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Spangler SA, Jaarsma D, De Graaff E, Wulf PS, Akhmanova A, Hoogenraad CC. Differential expression of liprin-α family proteins in the brain suggests functional diversification. J Comp Neurol 2011; 519:3040-60. [DOI: 10.1002/cne.22665] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Thyrock A, Stehling M, Waschbüsch D, Barnekow A. Characterizing the interaction between the Rab6 GTPase and Mint3 via flow cytometry based FRET analysis. Biochem Biophys Res Commun 2010; 396:679-83. [PMID: 20447381 DOI: 10.1016/j.bbrc.2010.04.161] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 04/28/2010] [Indexed: 11/25/2022]
Abstract
In extension to previously applied techniques like yeast two-hybrid and GST pull-down assays, we successfully established a FACS-based FRET analysis to investigate the interaction of the Mint3 adaptor protein and the small Rab GTPase Rab6A in living mammalian cells. A Mint3 mutant containing only the PTB domain (Mint3Delta6) is able to interact with the constitutively active form of Rab6A. Mint3Delta4, a mutant lacking part of the PTB domain was unable to interact with Rab6A in GST pull-down analysis and did not produce FRET signals, when co-expressed with active Rab6A. We demonstrate that this FACS-based FRET analysis is a suitable method for interaction studies between two proteins in living cells.
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Affiliation(s)
- Anika Thyrock
- Department of Experimental Tumorbiology, University Muenster, Badestr 9, D-48149 Muenster, Germany.
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Yao LL, Liu XY, Jin JY, Tao BB, Chen YJ, Yu YC, Bian WH, Yu J, Huang J, Wang YG. Expression and ultrastructural localization of Mint2 in the spinal cord of rats. Mol Biol Rep 2010; 38:667-73. [PMID: 20369384 DOI: 10.1007/s11033-010-0153-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 03/25/2010] [Indexed: 12/11/2022]
Abstract
Mint protein family, as adaptor molecules, contains three members, Mint1, Mint2 and Mint3. Although Mint3 is ubiquitously expressed, Mint1 and Mint2 have been reported to express specifically in neuron. Here we demonstrated Mint1 and Mint2 expression pattern in rat spinal cord. The protein level of Mint2 was found to be higher than that of Mint1 in rat spinal by western blot. In an attempt to know Mint2 distribution in the spinal cord of rat, in situ hybridization was carried out, Mint2 mRNA was showed to be ubiquitously distributed in cervical, thoracic and lumbar sections of rat spinal cord, and high intensive signal was detected in motor neurons. These were further confirmed by fluorescent immunohistochemistry, Mint2 was also found to exist throughout gray matter especially motor neurons where Mint2 was mainly located in perikaryon, however, Mint1 was showed to be relatively lower. By electron microscope, Mint2 was found to be mainly located in vesicles in perikaryon in motor neuron of lumbar section, and at the same time Mint2 was located in axons in myelin and presynaptic terminals. These data suggest that Mint2 may play more important role in spinal cord than the other two family members.
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Affiliation(s)
- Ling-Ling Yao
- Department of Physiology and Pathophysiology, Fudan University Shanghai Medical College, and Neurology Department of ShangHai Tenth People Hospital, Shanghai, 200032, China
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Mitchell JC, Perkinton MS, Yates DM, Lau KF, Rogelj B, Miller CC, McLoughlin DM. Expression of the neuronal adaptor protein X11alpha protects against memory dysfunction in a transgenic mouse model of Alzheimer's disease. J Alzheimers Dis 2010; 20:31-6. [PMID: 20378958 PMCID: PMC3023903 DOI: 10.3233/jad-2009-1341] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
X11alpha is a neuronal-specific adaptor protein that binds to the amyloid-beta protein precursor (AbetaPP). Overexpression of X11alpha reduces Abeta production but whether X11alpha also protects against Abeta-related memory dysfunction is not known. To test this possibility, we crossed X11alpha transgenic mice with AbetaPP-Tg2576 mice. AbetaPP-Tg2576 mice produce high levels of brain Abeta and develop age-related defects in memory function that correlate with increasing Abeta load. Overexpression of X11alpha alone had no detectable adverse effect upon behavior. However, X11alpha reduced brain Abeta levels and corrected spatial reference memory defects in aged X11alpha/AbetaPP double transgenics. Thus, X11alpha may be a therapeutic target for Alzheimer's disease.
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Affiliation(s)
- Jacqueline C. Mitchell
- MRC Centre for Neurodegeneration Research, King’s College London, Institute of Psychiatry, London, UK
| | - Michael S. Perkinton
- MRC Centre for Neurodegeneration Research, King’s College London, Institute of Psychiatry, London, UK
| | - Darran M. Yates
- MRC Centre for Neurodegeneration Research, King’s College London, Institute of Psychiatry, London, UK
| | - Kwok-Fai Lau
- Department of Biochemistry (Science), The Chinese University of Hong Kong, Shatin NT, Hong Kong SAR
| | - Boris Rogelj
- MRC Centre for Neurodegeneration Research, King’s College London, Institute of Psychiatry, London, UK
| | - Christopher C.J. Miller
- MRC Centre for Neurodegeneration Research, King’s College London, Institute of Psychiatry, London, UK
| | - Declan M. McLoughlin
- MRC Centre for Neurodegeneration Research, King’s College London, Institute of Psychiatry, London, UK
- Department of Psychiatry and Trinity College Institute of Neuroscience, Trinity College Dublin, St Patrick’s University Hospital, Dublin, Ireland
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Mitchell JC, Ariff BB, Yates DM, Lau KF, Perkinton MS, Rogelj B, Stephenson JD, Miller CCJ, McLoughlin DM. X11beta rescues memory and long-term potentiation deficits in Alzheimer's disease APPswe Tg2576 mice. Hum Mol Genet 2009; 18:4492-500. [PMID: 19744962 DOI: 10.1093/hmg/ddp408] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Increased production and deposition of amyloid beta-protein (Abeta) are believed to be key pathogenic events in Alzheimer's disease. As such, routes for lowering cerebral Abeta levels represent potential therapeutic targets for Alzheimer's disease. X11beta is a neuronal adaptor protein that binds to the intracellular domain of the amyloid precursor protein (APP). Overexpression of X11beta inhibits Abeta production in a number of experimental systems. However, whether these changes to APP processing and Abeta production induced by X11beta overexpression also induce beneficial effects to memory and synaptic plasticity are not known. We report here that X11beta-mediated reduction in cerebral Abeta is associated with normalization of both cognition and in vivo long-term potentiation in aged APPswe Tg2576 transgenic mice that model the amyloid pathology of Alzheimer's disease. Overexpression of X11beta itself has no detectable adverse effects upon mouse behaviour. These findings support the notion that modulation of X11beta function represents a therapeutic target for Abeta-mediated neuronal dysfunction in Alzheimer's disease.
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Affiliation(s)
- Jacqueline C Mitchell
- MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry, London SE5 8AF, UK
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12
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Saluja I, Paulson H, Gupta A, Turner RS. X11alpha haploinsufficiency enhances Abeta amyloid deposition in Alzheimer's disease transgenic mice. Neurobiol Dis 2009; 36:162-8. [PMID: 19631749 DOI: 10.1016/j.nbd.2009.07.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 07/02/2009] [Accepted: 07/13/2009] [Indexed: 10/20/2022] Open
Abstract
The neuronal adaptor protein X11alpha/mint-1/APBA-1 binds to the cytoplasmic domain of the amyloid precursor protein (APP) to modulate its trafficking and metabolism. We investigated the consequences of reducing X11alpha in a mouse model of Alzheimer's disease (AD). We crossed hAPPswe/PS-1DeltaE9 transgenic (AD tg) mice with X11alpha heterozygous knockout mice in which X11alpha expression is reduced by approximately 50%. The APP C-terminal fragments C99 and C83, as well as soluble Abeta40 and Abeta42, were increased significantly in brain of X11alpha haploinsufficient mice. Abeta/amyloid plaque burden also increased significantly in the hippocampus and cortex of one year old AD tg/X11alpha (+/-) mice compared to AD tg mice. In contrast, the levels of sAPPalpha and sAPPbeta were not altered significantly in AD tg/X11alpha (+/-) mice. The increased neuropathological indices of AD in mice expressing reduced X11alpha suggest a normal suppressor role for X11alpha on CNS Abeta/amyloid deposition.
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13
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Abstract
Understanding how emotion is generated, how conflicting emotions are regulated, and how emotional states relate to sophisticated behaviors is a crucial challenge in brain research. Model animals showing selective emotion-related phenotypes are highly useful for examining these issues. Here, we describe a novel mouse model that withdraws in approach-avoidance conflicts. X11-like (X11L)/Mint2 is a neuronal adapter protein with multiple protein-protein interaction domains that interacts with several proteins involved in modulating neuronal activity. X11L-knock-out (KO) mice were subordinate under competitive feeding conditions. X11L-KO mice lost significantly more weight than cohoused wild-type mice without signs of decreased motivation to eat or physical weakness. In a resident-intruder test, X11L-KO mice showed decreased intruder exploration behavior. Moreover, X11L-KO mice displayed decreased marble-burying, digging and burrowing behaviors, indicating aberrant ethological responses to attractive stimuli. In contrast, X11L-KO mice were indistinguishable from wild-type mice in the open field, elevated plus maze, and light/dark transition tests, which are often used to assess anxiety-like behavior. Neurochemical analysis revealed a monoamine imbalance in several forebrain regions. The defective ethological responses and social behaviors in X11L-KO mice were rescued by the expression of X11L under a Camk2a promoter using the Tet-OFF system during development. These findings suggest that X11L is involved in the development of neuronal circuits that contribute to conflict resolution.
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14
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Zhang Y, Wang YG, Zhang Q, Liu XJ, Liu X, Jiao L, Zhu W, Zhang ZH, Zhao XL, He C. Interaction of Mint2 with TrkA is involved in regulation of nerve growth factor-induced neurite outgrowth. J Biol Chem 2009; 284:12469-79. [PMID: 19265194 DOI: 10.1074/jbc.m809214200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
TrkA receptor signaling is essential for nerve growth factor (NGF)-induced survival and differentiation of sensory neurons. To identify possible effectors or regulators of TrkA signaling, yeast two-hybrid screening was performed using the intracellular domain of TrkA as bait. We identified muc18-1-interacting protein 2 (Mint2) as a novel TrkA-binding protein and found that the phosphotyrosine binding domain of Mint2 interacted with TrkA in a phosphorylation- and ligand-independent fashion. Coimmunoprecipitation assays showed that endogenous TrkA interacted with Mint2 in rat tissue homogenates, and immunohistochemical evidence revealed that Mint2 and TrkA colocalized in rat dorsal root ganglion neurons. Furthermore, Mint2 overexpression inhibited NGF-induced neurite outgrowth in both PC12 and cultured dorsal root ganglion neurons, whereas inhibition of Mint2 expression by RNA interference facilitated NGF-induced neurite outgrowth. Moreover, Mint2 was found to promote the retention of TrkA in the Golgi apparatus and inhibit its surface sorting. Taken together, our data provide evidence that Mint2 is a novel TrkA-regulating protein that affects NGF-induced neurite outgrowth, possibly through a mechanism involving retention of TrkA in the Golgi apparatus.
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Affiliation(s)
- Yong Zhang
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology, Ministry of Education, Second Military Medical University, Shanghai 200433, China
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15
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Abstract
Ca(2+)-dependent cell-cell adhesion is regulated by the cadherin family of cell adhesion proteins. Cadherins form trans-interactions on opposing cell surfaces which result in weak cell-cell adhesion. Stronger cell-cell adhesion occurs by clustering of cadherins and through changes in the organization of the actin cytoskeleton. Although cadherins were thought to bind directly to the actin cytoskeleton through cytoplasmic proteins, termed alpha- and beta-catenin, recent studies with purified proteins indicate that the interaction is not direct, and instead an allosteric switch in alpha-catenin may mediate actin cytoskeleton reorganization. Organization and function of the cadherin-catenin complex are additionally regulated by phosphorylation and endocytosis. Direct studies of cell-cell adhesion has revealed that the cadherin-catenin complex and the underlying actin cytoskeleton undergo a series of reorganizations that are controlled by the Rho GTPases, Rac1 and RhoA, that result in the expansion and completion of cell-cell adhesion. In the present article, in vitro protein assembly studies and live-cell studies of de novo cell-cell adhesion are discussed in the context of how the cadherin-catenin complex and the actin cytoskeleton regulate cell-cell adhesion.
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Shrivastava-Ranjan P, Faundez V, Fang G, Rees H, Lah JJ, Levey AI, Kahn RA. Mint3/X11gamma is an ADP-ribosylation factor-dependent adaptor that regulates the traffic of the Alzheimer's Precursor protein from the trans-Golgi network. Mol Biol Cell 2008; 19:51-64. [PMID: 17959829 PMCID: PMC2174186 DOI: 10.1091/mbc.e07-05-0465] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Revised: 09/04/2007] [Accepted: 10/12/2007] [Indexed: 11/11/2022] Open
Abstract
Beta-amyloid peptides (Abeta) are the major component of plaques in brains of Alzheimer's patients, and are they derived from the proteolytic processing of the beta-amyloid precursor protein (APP). The movement of APP between organelles is highly regulated, and it is tightly connected to its processing by secretases. We proposed previously that transport of APP within the cell is mediated in part through its sorting into Mint/X11-containing carriers. To test our hypothesis, we purified APP-containing vesicles from human neuroblastoma SH-SY5Y cells, and we showed that Mint2/3 are specifically enriched and that Mint3 and APP are present in the same vesicles. Increasing cellular APP levels increased the amounts of both APP and Mint3 in purified vesicles. Additional evidence supporting an obligate role for Mint3 in traffic of APP from the trans-Golgi network to the plasma membrane include the observations that depletion of Mint3 by small interference RNA (siRNA) or mutation of the Mint binding domain of APP changes the export route of APP from the basolateral to the endosomal/lysosomal sorting route. Finally, we show that increased expression of Mint3 decreased and siRNA-mediated knockdowns increased the secretion of the neurotoxic beta-amyloid peptide, Abeta(1-40). Together, our data implicate Mint3 activity as a critical determinant of post-Golgi APP traffic.
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Affiliation(s)
- Punya Shrivastava-Ranjan
- Departments of *Biochemistry
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322-3050
| | - Victor Faundez
- Cell Biology, and
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322-3050
| | - Guofu Fang
- Neurology and
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322-3050
| | - Howard Rees
- Neurology and
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322-3050
| | - James J. Lah
- Neurology and
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322-3050
| | - Allan I. Levey
- Neurology and
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322-3050
| | - Richard A. Kahn
- Departments of *Biochemistry
- the Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322-3050
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Kovalenko T, Osadchenko I, Nikonenko A, Lushnikova I, Voronin K, Nikonenko I, Muller D, Skibo G. Ischemia-induced modifications in hippocampal CA1 stratum radiatum excitatory synapses. Hippocampus 2006; 16:814-25. [PMID: 16892187 DOI: 10.1002/hipo.20211] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Relatively mild ischemic episode can initiate a chain of events resulting in delayed cell death and significant lesions in the affected brain regions. We studied early synaptic modifications after brief ischemia modeled in rats by transient vessels' occlusion in vivo or oxygen-glucose deprivation in vitro and resulting in delayed death of hippocampal CA1 pyramidal cells. Electron microscopic analysis of excitatory spine synapses in CA1 stratum radiatum revealed a rapid increase of the postsynaptic density (PSD) thickness and length, as well as formation of concave synapses with perforated PSD during the first 24 h after ischemic episode, followed at the long term by degeneration of 80% of synaptic contacts. In presynaptic terminals, ischemia induced a depletion of synaptic vesicles and changes in their spatial arrangement: they became more distant from active zones and had larger intervesicle spacing compared to controls. These rapid structural synaptic changes could be implicated in the mechanisms of cell death or adaptive plasticity. Comparison of the in vivo and in vitro model systems used in the study demonstrated a general similarity of these early morphological changes, confirming the validity of the in vitro model for studying synaptic structural plasticity.
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Affiliation(s)
- Tatiana Kovalenko
- Department of Cytology, Bogomoletz Institute of Physiology, Kiev, Ukraine
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18
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Sano Y, Syuzo-Takabatake A, Nakaya T, Saito Y, Tomita S, Itohara S, Suzuki T. Enhanced Amyloidogenic Metabolism of the Amyloid β-Protein Precursor in the X11L-deficient Mouse Brain. J Biol Chem 2006; 281:37853-60. [PMID: 17032642 DOI: 10.1074/jbc.m609312200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
X11L, a neuronal adaptor protein, associates with the cytoplasmic domain of APP and suppresses APP cellular metabolism. APP is the precursor of Abeta, whose metabolism is strongly implicated in Alzheimer disease pathogenesis. To examine the roles of X11L function in APP metabolism, including the generation of Abeta in the brain, we produced X11L-deficient mutant mice on the C57BL/6 background. The mutant mice did not exhibit histopathological alterations or compensatory changes in the expression of other X11 family proteins, X11 and X11L2. The expression level and distribution of APP in the brain of mutant mice were also identical to those in wild-type mice. However, in the hippocampus, where substantial levels of X11L and APP are expressed, the mutant mice exhibited a significant increase in the level of the C-terminal fragments of APP produced by cleavage with beta-secretase but not alpha-secretase. The levels of Abeta were increased in the hippocampus of aged mutant mice as compared with age-matched controls. These observations clearly indicate that X11L suppresses the amyloidogenic but not amyloidolytic processing of APP in regions of the brain such as the hippocampus, which express significant levels of X11L.
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Affiliation(s)
- Yoshitake Sano
- Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan
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Rogelj B, Mitchell JC, Miller CCJ, McLoughlin DM. The X11/Mint family of adaptor proteins. ACTA ACUST UNITED AC 2006; 52:305-15. [PMID: 16764936 DOI: 10.1016/j.brainresrev.2006.04.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 03/27/2006] [Accepted: 04/16/2006] [Indexed: 12/25/2022]
Abstract
The X11 protein family are multidomain proteins composed of a conserved PTB domain and two C-terminal PDZ domains. They are involved in formation of multiprotein complexes and two of the family members, X11alpha and X11beta, are expressed primarily in neurones. Not much is known about the principal function of X11s, but through interactions with other neuronal proteins, they are believed to be involved in regulating neuronal signaling, trafficking and plasticity. Furthermore, they have been shown to modulate processing of APP and accumulation of Abeta, making them potential therapeutic targets for Alzheimer's disease. This article reviews the known interactions of the different X11s and their involvement in Alzheimer's disease.
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Affiliation(s)
- Boris Rogelj
- King's College London, MRC Centre for Neurodegeneration Research, Department of Neuroscience, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK
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Kimura K, Kitano J, Nakajima Y, Nakanishi S. Hyperpolarization-activated, cyclic nucleotide-gated HCN2 cation channel forms a protein assembly with multiple neuronal scaffold proteins in distinct modes of protein-protein interaction. Genes Cells 2005; 9:631-40. [PMID: 15265006 DOI: 10.1111/j.1356-9597.2004.00752.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hyperpolarization-activated cation currents, termed Ih, are non-uniformly distributed along dendritic arbors with current density increasing with increasing distance from the soma. The non-uniform distribution of Ih currents contributes to normalization of location-dependent variability in temporal integration of synaptic input, but the molecular basis for the graded HCN distribution remains to be investigated. The hyperpolarization-activated, cyclic nucleotide-gated cation channels (HCNs) underlie Ih currents and consist of four members (HCN1-HCN4) of the gene family in mammals. In this investigation, we report that HCN2 forms a protein assembly with tamalin, S-SCAM and Mint2 scaffold proteins, using several different approaches including immunoprecipitation of rat brain and heterologously expressing cell extracts and glutathione S-transferase pull-down assays. The PDZ domain of tamalin interacts with HCN2 at both the PDZ-binding motif and the internal carboxy-terminal tail of HCN2, whereas binding of the PDZ domain of S-SCAM occurs at the cyclic nucleotide-binding domain (CNBD) and the CNBD-downstream sequence of the carboxy-terminal tail of HCN2. A protein assembly between HCN2 and Mint2 is formed by the interaction of the munc18-interacting domain of Mint2 with the CNBD-downstream sequence of HCN2. The results demonstrate that HCN2 forms a protein complex with multiple neuronal scaffold proteins in distinct modes of protein-protein interaction.
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Affiliation(s)
- Kouji Kimura
- Department of Biological Sciences, Faculty of Medicine, and Department of Molecular and System Biology, Graduate School of Biostudies, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
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Lee JH, Lau KF, Perkinton MS, Standen CL, Rogelj B, Falinska A, McLoughlin DM, Miller CCJ. The neuronal adaptor protein X11beta reduces amyloid beta-protein levels and amyloid plaque formation in the brains of transgenic mice. J Biol Chem 2004; 279:49099-104. [PMID: 15347685 DOI: 10.1074/jbc.m405602200] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Accumulation of cerebral amyloid beta-protein (Abeta) is believed to be part of the pathogenic process in Alzheimer's disease. Abeta is derived by proteolytic cleavage from a precursor protein, the amyloid precursor protein (APP). APP is a type-1 membrane-spanning protein, and its carboxyl-terminal intracellular domain binds to X11beta, a neuronal adaptor protein. X11beta has been shown to inhibit the production of Abeta in transfected non-neuronal cells in culture. However, whether this is also the case in vivo in the brain and whether X11beta can also inhibit the deposition of Abeta as amyloid plaques is not known. Here we show that transgenic overexpression of X11beta in neurons leads to a decrease in cerebral Abeta levels in transgenic APPswe Tg2576 mice that are a model of the amyloid pathology of Alzheimer's disease. Moreover, overexpression of X11beta retards amyloid plaque formation in these APPswe mice. Our findings suggest that modulation of X11beta function may represent a novel therapeutic approach for preventing the amyloid pathology of Alzheimer's disease.
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Affiliation(s)
- Ju-Hyun Lee
- Department of Neuroscience and Section of Old Age Psychiatry, The Institute of Psychiatry, King's College London SE5 8AF, United Kingdom
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King GD, Scott Turner R. Adaptor protein interactions: modulators of amyloid precursor protein metabolism and Alzheimer's disease risk? Exp Neurol 2004; 185:208-19. [PMID: 14736502 DOI: 10.1016/j.expneurol.2003.10.011] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cytoplasmic C-terminus of APP plays critical roles in its cellular trafficking and delivery to proteases. Adaptor proteins with phosphotyrosine-binding (PTB) domains, including those in the X11, Fe65, and c-Jun N-terminal kinase (JNK)-interacting protein (JIP) families, bind specifically to the absolutely conserved -YENPTY- motif in the APP C-terminus to regulate its trafficking and processing. Compounds that modulate APP-adaptor protein interactions may inhibit Abeta generation by specifically targeting the substrate (APP) instead of the enzyme (beta- or gamma-secretase). Genetic polymorphisms in (or near) adaptor proteins may influence risk of sporadic AD by interacting with APP in vivo to modulate its trafficking and processing to Abeta.
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Affiliation(s)
- Gwendalyn D King
- Neuroscience Program, University of Michigan, Ann Arbor, MI 48105, USA
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Lee JH, Lau KF, Perkinton MS, Standen CL, Shemilt SJA, Mercken L, Cooper JD, McLoughlin DM, Miller CCJ. The neuronal adaptor protein X11alpha reduces Abeta levels in the brains of Alzheimer's APPswe Tg2576 transgenic mice. J Biol Chem 2003; 278:47025-9. [PMID: 12970358 DOI: 10.1074/jbc.m300503200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Increased production and deposition of the 40-42-amino acid beta-amyloid peptide (Abeta) is believed to be central to the pathogenesis of Alzheimer's disease. Abeta is derived from the amyloid precursor protein (APP), but the mechanisms that regulate APP processing to produce Abeta are not fully understood. X11alpha (also known as munc-18-interacting protein-1 (Mint1)) is a neuronal adaptor protein that binds APP and modulates APP processing in transfected non-neuronal cells. To investigate the in vivo effect of X11alpha on Abeta production in the brain, we created transgenic mice that overexpress X11alpha and crossed these with transgenics harboring a familial Alzheimer's disease mutant APP that produces increased levels of Abeta (APPswe Tg2576 mice). Analyses of Abeta levels in the offspring generated from two separate X11alpha founder mice revealed a significant, approximate 20% decrease in Abeta(1-40) in double transgenic mice expressing APPswe/X11alpha compared with APPswe mice. At a key time point in Abeta plaque deposition (8 months old), the number of Abeta plaques was also deceased in APPswe/X11alpha mice. Thus, we report here the first demonstration that X11alpha inhibits Abeta production and deposition in vivo in the brain.
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Affiliation(s)
- Ju-Hyun Lee
- Department of Neuroscience and Section of Old Age Psychiatry, The Institute of Psychiatry, Kings College, De Crespigny Park, Denmark Hill, London SE5 8AF, U.K
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Ma YJ, Okamoto M, Gu F, Obata K, Matsuyama T, Desaki J, Tanaka J, Sakanaka M. Neuronal distribution of EHSH1/intersectin: molecular linker between clathrin-mediated endocytosis and signaling pathways. J Neurosci Res 2003; 71:468-77. [PMID: 12548702 DOI: 10.1002/jnr.10500] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent research indicates that the novel multimodular adaptor protein EHSH1 plays an important role in a partnership between clathrin-mediated endocytosis and intracellular signaling pathways, including the MAPK pathway, receptor-tyrosine kinase/ras-mediated pathway, and the rho family of the GTPase-dependent pathway. We report the detailed expression pattern of EHSH1 in the rat CNS, using separate cultures of neurons, astrocytes, and microglia, and biochemical and immunohistochemical analyses. Cultured neurons from the cortex express primarily the long isoform EHSH1-l, as well as a small amount of the short isoform EHSH1-s. Cultured astrocytes express EHSH1-s, at a level similar to neurons, and a trace of EHSH1-l. Cultured microglia express only EHSH1-s. Double immunofluorescent staining of cortical sections showed that EHSH1 is expressed predominantly in neurons. These results suggest that EHSH1-l is a primary isoform and that EHSH1-l is highly enriched in neurons in the rat adult CNS. Immunohistochemistry of a series of brain sections revealed widespread distribution of EHSH1 throughout the brain. Particularly intense immunoreactivity was observed in the somatodendritic region of neurons in Layer III of the neocortex, hippocampus, globus pallidus, subthalamic nucleus, and substantia nigra. Interestingly, all pyramidal neurons in Layer III of the neocortex and hippocampus did not necessarily exhibit equal levels of immunostaining. In contrast, little EHSH1 immunoreactivity was detected in septofimbrial nucleus and subfornical organ of the septal region, and solitary tract and external cuneate nuclei of the medulla. Variety in the expression of EHSH1 in neurons of different regions may reflect different conditions in clathrin-mediated endocytosis and the following signal transduction.
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Affiliation(s)
- Yong Jie Ma
- Department of Anatomy and Neuroscience, Ehime University School of Medicine, Ehime, Japan
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Ho CS, Marinescu V, Steinhilb ML, Gaut JR, Turner RS, Stuenkel EL. Synergistic effects of Munc18a and X11 proteins on amyloid precursor protein metabolism. J Biol Chem 2002; 277:27021-8. [PMID: 12016213 DOI: 10.1074/jbc.m201823200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
X11 proteins have been shown to modulate metabolism of the amyloid precursor protein (APP) and to reduce the secretion of beta-amyloid peptides (Abeta) that are associated with Alzheimer's disease. Whereas X11alpha interacts with APP via its phosphotyrosine-binding domain, recent reports indicate that additional regulatory interactions involve the N terminus of X11. Here we report that the syntaxin-1a-binding protein Munc18a, which interacts with the Munc18a-interacting domain (MID) at the N terminus of X11, strongly regulates the actions of X11 on APP metabolism. When co-expressed with X11alpha, Munc18a potentiated the retention of APP and suppression of Abeta secretion by X11alpha. As a result, the constitutive release of Abeta40 was nearly abolished. Experiments using N terminus deletion mutants of X11alpha/beta and the MID-deficient X11gamma revealed that the majority of the regulatory effect by Munc18a occurred independent of a direct interaction of Munc18a with X11, although the presence of X11 was required. Munc18a expression induced a small increase in beta-secretase activity, whereas it also intensified the reduction in Abeta40 secretion by X11alpha. These data indicate that Munc18a in concert with X11 acts to suppress gamma-secretase processing. We conclude that Munc18a acts through direct and indirect interactions with X11 proteins and powerfully regulates APP metabolism and Abeta secretion.
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Affiliation(s)
- Chi S Ho
- Department of Physiology, Institute of Gerontology, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
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