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Yasui T, Mashiko M, Obi A, Mori H, Ito-Murata M, Hayakawa H, Kikuchi S, Hosaka M, Kubota C, Torii S, Gomi H. Insulin granule morphology and crinosome formation in mice lacking the pancreatic β cell-specific phogrin (PTPRN2) gene. Histochem Cell Biol 2024; 161:223-238. [PMID: 38150052 DOI: 10.1007/s00418-023-02256-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2023] [Indexed: 12/28/2023]
Abstract
We recently reported that phogrin, also known as IA-2β or PTPRN2, forms a complex with the insulin receptor in pancreatic β cells upon glucose stimulation and stabilizes insulin receptor substrate 2. In β cells of systemic phogrin gene knockout (IA-2β-/-) mice, impaired glucose-induced insulin secretion, decreased insulin granule density, and an increase in the number and size of lysosomes have been reported. Since phogrin is expressed not only in β cells but also in various neuroendocrine cells, the precise impact of phogrin expressed in β cells on these cells remains unclear. In this study, we performed a comprehensive analysis of morphological changes in RIP-Cre+/-Phogrinflox/flox (βKO) mice with β cell-specific phogrin gene knockout. Compared to control RIP-Cre+/- Phogrin+/+ (Ctrl) mice, aged βKO mice exhibited a decreased density of insulin granules, which can be categorized into three subtypes. While no differences were observed in the density and size of lysosomes and crinosomes, organelles involved in insulin granule reduction, significant alterations in the regions of lysosomes responding positively to carbohydrate labeling were evident in young βKO mice. These alterations differed from those in Ctrl mice and continued to change with age. These electron microscopic findings suggest that phogrin expression in pancreatic β cells plays a role in insulin granule homeostasis and crinophagy during aging, potentially through insulin autocrine signaling and other mechanisms.
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Affiliation(s)
- Tadashi Yasui
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Mutsumi Mashiko
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Akihiro Obi
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Hiroyuki Mori
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Moeko Ito-Murata
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Hiroki Hayakawa
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Shota Kikuchi
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan
| | - Masahiro Hosaka
- Laboratory of Molecular Life Sciences, Department of Biotechnology, Akita Prefectural University, 241-438 Kaidobata-nishi, Nakano Shimoshinjo, Akita, 010-0195, Japan
| | - Chisato Kubota
- Center for Food Science and Wellness, Gunma University, 3-39-22 Showa, Maebashi, Gunma, 371-8511, Japan
- Takasaki University of Health and Welfare, 37-1 Nakaorui, Takasaki, Gunma, 370-0033, Japan
| | - Seiji Torii
- Center for Food Science and Wellness, Gunma University, 3-39-22 Showa, Maebashi, Gunma, 371-8511, Japan
| | - Hiroshi Gomi
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan.
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2
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Bansal V, Winkelmann BR, Dietrich JW, Boehm BO. Whole-exome sequencing in familial type 2 diabetes identifies an atypical missense variant in the RyR2 gene. Front Endocrinol (Lausanne) 2024; 15:1258982. [PMID: 38444585 PMCID: PMC10913019 DOI: 10.3389/fendo.2024.1258982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 01/10/2024] [Indexed: 03/07/2024] Open
Abstract
Genome-wide association studies have identified several hundred loci associated with type 2 diabetes mellitus (T2DM). Additionally, pathogenic variants in several genes are known to cause monogenic diabetes that overlaps clinically with T2DM. Whole-exome sequencing of related individuals with T2DM is a powerful approach to identify novel high-penetrance disease variants in coding regions of the genome. We performed whole-exome sequencing on four related individuals with T2DM - including one individual diagnosed at the age of 33 years. The individuals were negative for mutations in monogenic diabetes genes, had a strong family history of T2DM, and presented with several characteristics of metabolic syndrome. A missense variant (p.N2291D) in the type 2 ryanodine receptor (RyR2) gene was one of eight rare coding variants shared by all individuals. The variant was absent in large population databases and affects a highly conserved amino acid located in a mutational hotspot for pathogenic variants in Catecholaminergic polymorphic ventricular tachycardia (CPVT). Electrocardiogram data did not reveal any cardiac abnormalities except a lower-than-normal resting heart rate (< 60 bpm) in two individuals - a phenotype observed in CPVT individuals with RyR2 mutations. RyR2-mediated Ca2+ release contributes to glucose-mediated insulin secretion and pathogenic RyR2 mutations cause glucose intolerance in humans and mice. Analysis of glucose tolerance testing data revealed that missense mutations in a CPVT mutation hotspot region - overlapping the p.N2291D variant - are associated with complete penetrance for glucose intolerance. In conclusion, we have identified an atypical missense variant in the RyR2 gene that co-segregates with diabetes in the absence of overt CPVT.
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Affiliation(s)
- Vikas Bansal
- Department of Pediatrics, University of California San Diego, La Jolla, CA, United States
- Institute of Genomic Medicine, University of California San Diego, La Jolla, CA, United States
| | | | - Johannes W Dietrich
- Diabetes, Endocrinology and Metabolism Section, Department of Internal Medicine I, St. Josef Hospital, Ruhr University Hospitals, Bochum, Germany
- Diabetes Center Bochum-Hattingen, St. Elisabeth-Hospital Blankenstein, Hattingen, Germany
- Center for Rare Endocrine Diseases, Ruhr Center for Rare Diseases (CeSER), Ruhr University Bochum and Witten/Herdecke University, Bochum, Germany
- Center for Diabetes Technology, Catholic Hospitals Bochum, Bochum, Germany
| | - Bernhard O Boehm
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
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3
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Kalnytska O, Qvist P, Kunz S, Conrad T, Willnow TE, Schmidt V. SORCS2 activity in pancreatic α-cells safeguards insulin granule formation and release from glucose-stressed β-cells. iScience 2024; 27:108725. [PMID: 38226160 PMCID: PMC10788290 DOI: 10.1016/j.isci.2023.108725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 09/18/2023] [Accepted: 12/11/2023] [Indexed: 01/17/2024] Open
Abstract
Sorting receptor SORCS2 is a stress-response factor protecting neurons from acute insults, such as during epilepsy. SORCS2 is also expressed in the pancreas, yet its action in this tissue remains unknown. Combining metabolic studies in SORCS2-deficient mice with ex vivo functional analyses and single-cell transcriptomics of pancreatic tissues, we identified a role for SORCS2 in protective stress response in pancreatic islets, essential to sustain insulin release. We show that SORCS2 is predominantly expressed in islet alpha cells. Loss of expression coincides with inability of these cells to produce osteopontin, a secreted factor that facilitates insulin release from stressed beta cells. In line with diminished osteopontin levels, beta cells in SORCS2-deficient islets show gene expression patterns indicative of aggravated cell stress, and exhibit defects in insulin granule maturation and a blunted glucose response. These findings corroborate a function for SORCS2 in protective stress response that extends to metabolism.
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Affiliation(s)
- Oleksandra Kalnytska
- Molecular Cardiovascular Research, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
- Charité – Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Per Qvist
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - Séverine Kunz
- Technology Platform for Electron Microscopy, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Thomas Conrad
- Genomics Technology Platform, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 10115 Berlin, Germany
| | - Thomas E. Willnow
- Molecular Cardiovascular Research, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
- Charité – Universitätsmedizin Berlin, 10117 Berlin, Germany
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - Vanessa Schmidt
- Molecular Cardiovascular Research, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
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4
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Butyrate Protects Pancreatic Beta Cells from Cytokine-Induced Dysfunction. Int J Mol Sci 2021; 22:ijms221910427. [PMID: 34638768 PMCID: PMC8508700 DOI: 10.3390/ijms221910427] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/24/2021] [Accepted: 09/25/2021] [Indexed: 12/12/2022] Open
Abstract
Pancreatic beta cell dysfunction caused by metabolic and inflammatory stress contributes to the development of type 2 diabetes (T2D). Butyrate, produced by the gut microbiota, has shown beneficial effects on glucose metabolism in animals and humans and may directly affect beta cell function, but the mechanisms are poorly described. The aim of this study was to investigate the effect of butyrate on cytokine-induced beta cell dysfunction in vitro. Mouse islets, rat INS-1E, and human EndoC-βH1 beta cells were exposed long-term to non-cytotoxic concentrations of cytokines and/or butyrate to resemble the slow onset of inflammation in T2D. Beta cell function was assessed by glucose-stimulated insulin secretion (GSIS), gene expression by qPCR and RNA-sequencing, and proliferation by incorporation of EdU into newly synthesized DNA. Butyrate protected beta cells from cytokine-induced impairment of GSIS and insulin content in the three beta cell models. Beta cell proliferation was reduced by both cytokines and butyrate. Expressions of the beta cell specific genes Ins, MafA, and Ucn3 reduced by the cytokine IL-1β were not affected by butyrate. In contrast, butyrate upregulated the expression of secretion/transport-related genes and downregulated inflammatory genes induced by IL-1β in mouse islets. In summary, butyrate prevents pro-inflammatory cytokine-induced beta cell dysfunction.
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Fan F, Wu Y, Hara M, Rizk A, Ji C, Nerad D, Tamarina N, Lou X. Dynamin deficiency causes insulin secretion failure and hyperglycemia. Proc Natl Acad Sci U S A 2021; 118:e2021764118. [PMID: 34362840 PMCID: PMC8364113 DOI: 10.1073/pnas.2021764118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pancreatic β cells operate with a high rate of membrane recycling for insulin secretion, yet endocytosis in these cells is not fully understood. We investigate this process in mature mouse β cells by genetically deleting dynamin GTPase, the membrane fission machinery essential for clathrin-mediated endocytosis. Unexpectedly, the mice lacking all three dynamin genes (DNM1, DNM2, DNM3) in their β cells are viable, and their β cells still contain numerous insulin granules. Endocytosis in these β cells is severely impaired, resulting in abnormal endocytic intermediates on the plasma membrane. Although insulin granules are abundant, their release upon glucose stimulation is blunted in both the first and second phases, leading to hyperglycemia and glucose intolerance in mice. Dynamin triple deletion impairs insulin granule exocytosis and decreases intracellular Ca2+ responses and granule docking. The docking defect is correlated with reduced expression of Munc13-1 and RIM1 and reorganization of cortical F-actin in β cells. Collectively, these findings uncover the role of dynamin in dense-core vesicle endocytosis and secretory capacity. Insulin secretion deficiency in the absence of dynamin-mediated endocytosis highlights the risk of impaired membrane trafficking in endocrine failure and diabetes pathogenesis.
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Affiliation(s)
- Fan Fan
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Yumei Wu
- HHMI, Yale University School of Medicine, New Haven, CT 06510
- Departments of Neuroscience and Cell Biology, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510
| | - Manami Hara
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Chicago, Chicago, IL 60637
| | - Adam Rizk
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Chicago, Chicago, IL 60637
| | - Chen Ji
- Synapses and Circuits section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892
| | - Dan Nerad
- Emergency Medicine, Carl R. Darnall Army Medical Center, Fort Hood, TX 76544
| | - Natalia Tamarina
- Department of Medicine, The Kovler Diabetes Center, University of Chicago, Chicago, IL 60637
| | - Xuelin Lou
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226;
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Ludwig-Słomczyńska AH, Seweryn MT, Kapusta P, Pitera E, Mantaj U, Cyganek K, Gutaj P, Dobrucka Ł, Wender-Ożegowska E, Małecki MT, Wołkow PP. The transcriptome-wide association search for genes and genetic variants which associate with BMI and gestational weight gain in women with type 1 diabetes. Mol Med 2021; 27:6. [PMID: 33472578 PMCID: PMC7818927 DOI: 10.1186/s10020-020-00266-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 12/30/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Clinical data suggest that BMI and gestational weight gain (GWG) are strongly interconnected phenotypes; however, the genetic basis of the latter is rather unclear. Here we aim to find genes and genetic variants which influence BMI and/or GWG. METHODS We have genotyped 316 type 1 diabetics using Illumina Infinium Omni Express Exome-8 v1.4 arrays. The GIANT, ARIC and T2D-GENES summary statistics were used for TWAS (performed with PrediXcan) in adipose tissue. Next, the analysis of association of imputed expression with BMI in the general and diabetic cohorts (Analysis 1 and 2) or GWG (Analysis 3 and 4) was performed, followed by variant association analysis (1 Mb around identified loci) with the mentioned phenotypes. RESULTS In Analysis 1 we have found 175 BMI associated genes and 19 variants (p < 10-4) which influenced GWG, with the strongest association for rs11465293 in CCL24 (p = 3.18E-06). Analysis 2, with diabetes included in the model, led to discovery of 1812 BMI associated loci and 207 variants (p < 10-4) influencing GWG, with the strongest association for rs9690213 in PODXL (p = 9.86E-07). In Analysis 3, among 648 GWG associated loci, 2091 variants were associated with BMI (FDR < 0.05). In Analysis 4, 7 variants in GWG associated loci influenced BMI in the ARIC cohort. CONCLUSIONS Here, we have shown that loci influencing BMI might have an impact on GWG and GWG associated loci might influence BMI, both in the general and T1DM cohorts. The results suggest that both phenotypes are related to insulin signaling, glucose homeostasis, mitochondrial metabolism, ubiquitinoylation and inflammatory responses.
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Affiliation(s)
| | - Michał T Seweryn
- Center for Medical Genomics OMICRON, Jagiellonian University Medical College, Kraków, Poland
- Department of Cancer Biology and Genetics, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Przemysław Kapusta
- Center for Medical Genomics OMICRON, Jagiellonian University Medical College, Kraków, Poland
| | - Ewelina Pitera
- Center for Medical Genomics OMICRON, Jagiellonian University Medical College, Kraków, Poland
| | - Urszula Mantaj
- Department of Reproduction, Poznan University of Medical Sciences, Poznan, Poland
| | - Katarzyna Cyganek
- Department of Metabolic Diseases, University Hospital Kraków, Kraków, Poland
- Department of Metabolic Diseases, Jagiellonian University Medical College, Kraków, Poland
| | - Paweł Gutaj
- Department of Reproduction, Poznan University of Medical Sciences, Poznan, Poland
| | - Łucja Dobrucka
- Department of Metabolic Diseases, University Hospital Kraków, Kraków, Poland
| | - Ewa Wender-Ożegowska
- Department of Reproduction, Poznan University of Medical Sciences, Poznan, Poland
| | - Maciej T Małecki
- Department of Metabolic Diseases, University Hospital Kraków, Kraków, Poland
- Department of Metabolic Diseases, Jagiellonian University Medical College, Kraków, Poland
| | - Paweł P Wołkow
- Center for Medical Genomics OMICRON, Jagiellonian University Medical College, Kraków, Poland.
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7
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Kreutzberger AJB, Kiessling V, Doyle CA, Schenk N, Upchurch CM, Elmer-Dixon M, Ward AE, Preobraschenski J, Hussein SS, Tomaka W, Seelheim P, Kattan I, Harris M, Liang B, Kenworthy AK, Desai BN, Leitinger N, Anantharam A, Castle JD, Tamm LK. Distinct insulin granule subpopulations implicated in the secretory pathology of diabetes types 1 and 2. eLife 2020; 9:e62506. [PMID: 33164744 PMCID: PMC7738183 DOI: 10.7554/elife.62506] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/06/2020] [Indexed: 12/12/2022] Open
Abstract
Insulin secretion from β-cells is reduced at the onset of type-1 and during type-2 diabetes. Although inflammation and metabolic dysfunction of β-cells elicit secretory defects associated with type-1 or type-2 diabetes, accompanying changes to insulin granules have not been established. To address this, we performed detailed functional analyses of insulin granules purified from cells subjected to model treatments that mimic type-1 and type-2 diabetic conditions and discovered striking shifts in calcium affinities and fusion characteristics. We show that this behavior is correlated with two subpopulations of insulin granules whose relative abundance is differentially shifted depending on diabetic model condition. The two types of granules have different release characteristics, distinct lipid and protein compositions, and package different secretory contents alongside insulin. This complexity of β-cell secretory physiology establishes a direct link between granule subpopulation and type of diabetes and leads to a revised model of secretory changes in the diabetogenic process.
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Affiliation(s)
- Alex J B Kreutzberger
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Catherine A Doyle
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Noah Schenk
- Department of Pharmacology, University of MichiganAnn ArborUnited States
| | - Clint M Upchurch
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Margaret Elmer-Dixon
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Amanda E Ward
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Julia Preobraschenski
- Department of Neurobiology, Max Planck Institute for Biophysical ChemistryGöttingenGermany
- Cluster of Excellence in Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells and Institute for Auditory Neuroscience, University of GöttingenGöttingenGermany
| | - Syed S Hussein
- Department of Microbiology, University of VirginiaCharlottesvilleUnited States
| | - Weronika Tomaka
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Patrick Seelheim
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Iman Kattan
- Department of Neurobiology, Max Planck Institute for Biophysical ChemistryGöttingenGermany
| | - Megan Harris
- Department of Cell Biology, University of VirginiaCharlottesvilleUnited States
| | - Binyong Liang
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Anne K Kenworthy
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
| | - Bimal N Desai
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Norbert Leitinger
- Department of Pharmacology, University of VirginiaCharlottesvilleUnited States
| | - Arun Anantharam
- Department of Pharmacology, University of MichiganAnn ArborUnited States
| | - J David Castle
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department of Cell Biology, University of VirginiaCharlottesvilleUnited States
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of VirginiaCharlottesvilleUnited States
- Department for Molecular Physiology and Biological Physics, University of VirginiaCharlottesvilleUnited States
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CDK8 Regulates Insulin Secretion and Mediates Postnatal and Stress-Induced Expression of Neuropeptides in Pancreatic β Cells. Cell Rep 2020; 28:2892-2904.e7. [PMID: 31509750 DOI: 10.1016/j.celrep.2019.08.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 06/26/2019] [Accepted: 08/05/2019] [Indexed: 12/13/2022] Open
Abstract
Cyclin-dependent kinases (CDKs) contribute to vital cellular processes including cell cycle regulation. Loss of CDKs is associated with impaired insulin secretion and β cell survival; however, the function of CDK8 in β cells remains elusive. Here, we report that genetic ablation of Cdk8 improves glucose tolerance by increasing insulin secretion. We identify OSBPL3 as a CDK8-dependent phosphoprotein, which acts as a negative regulator of insulin secretion in response to glucose. We also show that embryonic gene silencing of neuropeptide Y in β cells is compromised in Cdk8-null mice, leading to continued expression into adulthood. Cdk8 ablation in β cells aggravates apoptosis and induces de novo expression of neuropeptides upon oxidative stress. Moreover, pancreatic islets exposed to stress display augmented apoptosis in the presence of these same neuropeptides. Our results reveal critical roles for CDK8 in β cell function and survival during metabolic stress that are in part mediated through de novo expression of neuropeptides.
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9
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CAPS1 Suppresses Tumorigenesis in Cholangiocarcinoma. Dig Dis Sci 2020; 65:1053-1063. [PMID: 31562609 DOI: 10.1007/s10620-019-05843-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 08/02/2019] [Indexed: 12/09/2022]
Abstract
BACKGROUND CAPS1 (calcium-dependent activator protein for secretion) is a multi-domain protein involved in regulating exocytosis of synaptic vesicles and dense-core vesicles. However, the expression and function of CAPS1 in cholangiocarcinoma (CCA) remains unclear. In the present study, we explored the role of CAPS1 in CCA carcinogenesis. METHODS CAPS1 expression was explored using western blotting and immunohistochemistry in four CCA cell lines and clinical samples from 90 cases of CCA. The clinical significance of CAPS1 was analyzed. The biological function of CAPS1 in CCA cells was detected in vitro and in vivo. The underlying mechanism of CAPS1 function was explored by detecting the expression of critical molecules in its associated signaling pathways. The mechanism of CAPS1 downregulation in tumor tissues was explored using in silico prediction and luciferase reporter assays. RESULTS CAPS1 expression was reduced in CCA cell lines and human tumor tissues. Loss of CAPS1 in tumor tissues was closely associated with poor prognosis of patients with CCA. Moreover, CAPS1 expression correlated significantly with tumor-node-metastasis stage, lymph node metastasis, and vascular invasion. Lentivirus-mediated CAPS1 overexpression substantially prevented clone formation, cell proliferation, and cell cycle progression. CAPS1 overexpression also suppressed carcinogenesis in nude mice. Mechanistically, CAPS1 overexpression greatly accelerated the ERK and p38 MAPK signal pathways. In addition, microRNA miR-30e-5p negatively regulated CAPS1 expression. CONCLUSION These data showed that CAPS1 functions as a tumor suppressor in CCA. Reduced CAPS1 expression could indicate poor prognosis of patients with CCA.
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10
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Genome-wide association study identifies novel risk variants from RPS6KA1, CADPS, VARS, and DHX58 for fasting plasma glucose in Arab population. Sci Rep 2020; 10:152. [PMID: 31932636 PMCID: PMC6957513 DOI: 10.1038/s41598-019-57072-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 12/20/2019] [Indexed: 12/14/2022] Open
Abstract
Consanguineous populations of the Arabian Peninsula, which has seen an uncontrolled rise in type 2 diabetes incidence, are underrepresented in global studies on diabetes genetics. We performed a genome-wide association study on the quantitative trait of fasting plasma glucose (FPG) in unrelated Arab individuals from Kuwait (discovery-cohort:n = 1,353; replication-cohort:n = 1,196). Genome-wide genotyping in discovery phase was performed for 632,375 markers from Illumina HumanOmniExpress Beadchip; and top-associating markers were replicated using candidate genotyping. Genetic models based on additive and recessive transmission modes were used in statistical tests for associations in discovery phase, replication phase, and meta-analysis that combines data from both the phases. A genome-wide significant association with high FPG was found at rs1002487 (RPS6KA1) (p-discovery = 1.64E-08, p-replication = 3.71E-04, p-combined = 5.72E-11; β-discovery = 8.315; β-replication = 3.442; β-combined = 6.551). Further, three suggestive associations (p-values < 8.2E-06) with high FPG were observed at rs487321 (CADPS), rs707927 (VARS and 2Kb upstream of VWA7), and rs12600570 (DHX58); the first two markers reached genome-wide significance in the combined analysis (p-combined = 1.83E-12 and 3.07E-09, respectively). Significant interactions of diabetes traits (serum triglycerides, FPG, and glycated hemoglobin) with homeostatic model assessment of insulin resistance were identified for genotypes heterozygous or homozygous for the risk allele. Literature reports support the involvement of these gene loci in type 2 diabetes etiology.
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11
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Taneera J, Mohammed I, Mohammed AK, Hachim M, Dhaiban S, Malek A, Dunér P, Elemam NM, Sulaiman N, Hamad M, Salehi A. Orphan G-protein coupled receptor 183 (GPR183) potentiates insulin secretion and prevents glucotoxicity-induced β-cell dysfunction. Mol Cell Endocrinol 2020; 499:110592. [PMID: 31550518 DOI: 10.1016/j.mce.2019.110592] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/15/2019] [Accepted: 09/20/2019] [Indexed: 12/28/2022]
Abstract
The expression and functional impact of most orphan G-protein coupled receptors (GPCRs) in β-cell is not fully understood. Microarray expression indicated that 36 orphan GPCRs are restricted in human islets, while 55 receptors overlapped between human islets and INS-1 cells. GPR183 showed higher expression in diabetic compared to non-diabetic human islets. GPR183 expression co-localized with β-cells while it was lacking in α-cells in human islets. The GPR183 agonist (7α-25-DHC) potentiated insulin secretion and protected against glucotoxicity-induced β-cell damage in human islets. Silencing of GPR183 in INS-1 cells decreased the expression of proinsulin genes, Pdx1, Mafa and impaired insulin secretion with a concomitant decrease in cAMP generation. Cultured INS-1 cells with 7α-25-DHC were associated with increased proliferation and expression of GPR183, INS2, PDX1, NeuroD, and INSR. In conclusion, the beneficial impact of GPR183 activation on β-cell function makes it a potential therapeutic target to prevent or reverse β-cell dysfunction.
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Affiliation(s)
- Jalal Taneera
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates; Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates.
| | - Israa Mohammed
- Department of Clinical Science, UMAS, Clinical Research Center, Lund University, Malmö, Sweden
| | - Abdul Khader Mohammed
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Mahmood Hachim
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Sarah Dhaiban
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Abdullah Malek
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - Pontus Dunér
- Department of Clinical Science, UMAS, Clinical Research Center, Lund University, Malmö, Sweden
| | - Noha M Elemam
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Nabil Sulaiman
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Mawieh Hamad
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; Department of Medical Laboratory Sciences, College of Health Sciences, University of Sharjah, Sharjah, United Arab Emirates
| | - Albert Salehi
- Department of Clinical Science, UMAS, Clinical Research Center, Lund University, Malmö, Sweden; Department of Neuroscience and Physiology, Metabolic Research Unit, University of Gothenburg, Gothenburg, Sweden.
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12
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In vitro fusion of single synaptic and dense core vesicles reproduces key physiological properties. Nat Commun 2019; 10:3904. [PMID: 31467284 PMCID: PMC6715626 DOI: 10.1038/s41467-019-11873-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 08/02/2019] [Indexed: 12/29/2022] Open
Abstract
Regulated exocytosis of synaptic vesicles is substantially faster than of endocrine dense core vesicles despite similar molecular machineries. The reasons for this difference are unknown and could be due to different regulatory proteins, different spatial arrangements, different vesicle sizes, or other factors. To address these questions, we take a reconstitution approach and compare regulated SNARE-mediated fusion of purified synaptic and dense core chromaffin and insulin vesicles using a single vesicle-supported membrane fusion assay. In all cases, Munc18 and complexin are required to restrict fusion in the absence of calcium. Calcium triggers fusion of all docked vesicles. Munc13 (C1C2MUN domain) is required for synaptic and enhanced insulin vesicle fusion, but not for chromaffin vesicles, correlating inversely with the presence of CAPS protein on purified vesicles. Striking disparities in calcium-triggered fusion rates are observed, increasing with curvature with time constants 0.23 s (synaptic vesicles), 3.3 s (chromaffin vesicles), and 9.1 s (insulin vesicles) and correlating with rate differences in cells.
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13
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Chen L, Pan X, Zhang YH, Huang T, Cai YD. Analysis of Gene Expression Differences between Different Pancreatic Cells. ACS OMEGA 2019; 4:6421-6435. [DOI: 10.1021/acsomega.8b02171] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Lei Chen
- School of Life Sciences, Shanghai University, Shanghai 200444, China
- College of Information Engineering, Shanghai Maritime University, Shanghai 201306, China
- Shanghai Key Laboratory of PMMP, East China Normal University, Shanghai 200241, China
| | - Xiaoyong Pan
- Department of Medical Informatics, Erasmus MC, Rotterdam 3014ZK, Netherlands
| | - Yu-Hang Zhang
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Tao Huang
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yu-Dong Cai
- School of Life Sciences, Shanghai University, Shanghai 200444, China
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14
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Shinoda Y, Sadakata T, Yagishita K, Kinameri E, Katoh-Semba R, Sano Y, Furuichi T. Aspects of excitatory/inhibitory synapses in multiple brain regions are correlated with levels of brain-derived neurotrophic factor/neurotrophin-3. Biochem Biophys Res Commun 2018; 509:429-434. [PMID: 30594389 DOI: 10.1016/j.bbrc.2018.12.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 12/14/2018] [Indexed: 12/29/2022]
Abstract
Appropriate synapse formation during development is necessary for normal brain function, and synapse impairment is often associated with brain dysfunction. Brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are key factors in regulating synaptic development. We previously reported that BDNF/NT-3 secretion was enhanced by calcium-dependent activator protein for secretion 2 (CADPS2). Although BDNF/NT-3 and CADPS2 are co-expressed in various brain regions, the effect of Cadps2-deficiency on brain region-specific BDNF/NT-3 levels and synaptic development remains elusive. Here, we show developmental changes of BDNF/NT-3 levels and we assess disruption of excitatory/inhibitory synapses in multiple brain regions (cerebellum, hypothalamus, striatum, hippocampus, parietal cortex and prefrontal cortex) of Cadps2 knockout (KO) mice compared with wild-type (WT) mice. Compared with WT, BDNF levels in KO mice were reduced in young/adult hippocampus, but increased in young hypothalamus, while NT-3 levels were reduced in adult cerebellum and young hippocampus, but increased in adult parietal cortex. Immunofluorescence of vGluT1, an excitatory synapse marker, and vGAT, an inhibitory synapse marker, in adult KO showed that vGluT1 was higher in the cerebellum and parietal cortex but lower in the hippocampus, whereas vGAT was lower in the hippocampus and parietal cortex compared with WT. Immunolabeling for both vGluT1 and vGAT was increased in the parietal cortex but vGAT was decreased in the cerebellum in adult KO compared with WT. These data suggest that CADPS2-mediated secretion of BDNF/NT-3 may be involved in development and maturation of synapses and in the balance between inhibitory and excitatory synapses.
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Affiliation(s)
- Yo Shinoda
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392, Japan; Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, Japan; Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama, 351-0198, Japan.
| | - Tetsushi Sadakata
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama, 351-0198, Japan; Education and Research Support Center, Gunma University Graduate School of Medicine, Maebashi, Gunma, 371-8511, Japan
| | - Kaori Yagishita
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, Japan
| | - Emi Kinameri
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama, 351-0198, Japan
| | - Ritsuko Katoh-Semba
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, Japan; Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama, 351-0198, Japan
| | - Yoshitake Sano
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, Japan
| | - Teiichi Furuichi
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, 278-8510, Japan; Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama, 351-0198, Japan.
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15
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Jinnah H, Ulbricht RJ. Using mouse models to unlock the secrets of non-synonymous RNA editing. Methods 2018; 156:40-45. [PMID: 30827465 DOI: 10.1016/j.ymeth.2018.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/05/2018] [Accepted: 10/22/2018] [Indexed: 11/26/2022] Open
Abstract
The deamination of adenosine to inosine by RNA editing is a widespread post-transcriptional process that expands genetic diversity. Selective substitution of inosine for adenosine in pre-mRNA transcripts can alter splicing, mRNA stability, and the amino acid sequence of the encoded protein. The functional consequences of RNA editing-dependent amino acid substitution are known for only a handful of RNA editing substrates. Many of these studies began in heterologous mammalian expression systems; however, the gold-standard for determining the functional significance of transcript-specific re-coding A-to-I editing events is the generation of a mouse model that expresses only one RNA editing-dependent isoform. The frequency of site-specific RNA editing varies spatially, temporally, and in some diseases, therefore, determining the profile of RNA editing frequency is also an important element of research. Here we review the strengths and weaknesses of existing mouse models for the study of RNA editing, as well as methods for quantifying RNA editing frequencies in vivo. Importantly, we highlight opportunities for future RNA editing studies in mice, projecting that improvements in genome editing and high-throughput sequencing technologies will allow the field to excel in coming years.
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Affiliation(s)
- Hussain Jinnah
- Vanderbilt University, Department of Pharmacology, 8140 Medical Research Building 3, Nashville, TN 37240-1104, United States.
| | - Randi J Ulbricht
- Missouri State University, Department of Biomedical Sciences, 901 South National Avenue, Springfield, MO 65897, United States.
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16
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Shaib AH, Staudt A, Harb A, Klose M, Shaaban A, Schirra C, Mohrmann R, Rettig J, Becherer U. Paralogs of the Calcium-Dependent Activator Protein for Secretion Differentially Regulate Synaptic Transmission and Peptide Secretion in Sensory Neurons. Front Cell Neurosci 2018; 12:304. [PMID: 30254567 PMCID: PMC6141663 DOI: 10.3389/fncel.2018.00304] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/21/2018] [Indexed: 12/29/2022] Open
Abstract
The two paralogs of the calcium-dependent activator protein for secretion (CAPS) are priming factors for synaptic vesicles (SVs) and neuropeptide containing large dense-core vesicles (LDCVs). Yet, it is unclear whether CAPS1 and CAPS2 regulate exocytosis of these two vesicle types differentially in dorsal root ganglion (DRG) neurons, wherein synaptic transmission and neuropeptide release are of equal importance. These sensory neurons transfer information from the periphery to the spinal cord (SC), releasing glutamate as the primary neurotransmitter, with co-transmission via neuropeptides in a subset of so called peptidergic neurons. Neuropeptides are key components of the information-processing machinery of pain perception and neuropathic pain generation. Here, we compared the ability of CAPS1 and CAPS2 to support priming of both vesicle types in single and double knock-out mouse (DRG) neurons using a variety of high-resolution live cell imaging methods. While CAPS1 was localized to synapses of all DRG neurons and promoted synaptic transmission, CAPS2 was found exclusively in peptidergic neurons and mediated LDCV exocytosis. Intriguingly, ectopic expression of CAPS2 empowered non-peptidergic neurons to drive LDCV fusion, thereby identifying CAPS2 as an essential molecular determinant for peptidergic signaling. Our results reveal that these distinct functions of both CAPS paralogs are based on their differential subcellular localization in DRG neurons. Our data suggest a major role for CAPS2 in neuropathic pain via control of neuropeptide release.
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Affiliation(s)
- Ali H. Shaib
- Department of Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Angelina Staudt
- Department of Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Ali Harb
- Department of Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
- ZHMB Junior Group, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Margarete Klose
- Department of Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Ahmed Shaaban
- ZHMB Junior Group, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Claudia Schirra
- Department of Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Ralf Mohrmann
- ZHMB Junior Group, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Jens Rettig
- Department of Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Ute Becherer
- Department of Cellular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
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17
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Hussain SS, Harris MT, Kreutzberger AJB, Inouye CM, Doyle CA, Castle AM, Arvan P, Castle JD. Control of insulin granule formation and function by the ABC transporters ABCG1 and ABCA1 and by oxysterol binding protein OSBP. Mol Biol Cell 2018. [PMID: 29540530 PMCID: PMC5935073 DOI: 10.1091/mbc.e17-08-0519] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In pancreatic β-cells, insulin granule membranes are enriched in cholesterol and are both recycled and newly generated. Cholesterol’s role in supporting granule membrane formation and function is poorly understood. ATP binding cassette transporters ABCG1 and ABCA1 regulate intracellular cholesterol and are important for insulin secretion. RNAi interference–induced depletion in cultured pancreatic β-cells shows that ABCG1 is needed to stabilize newly made insulin granules against lysosomal degradation; ABCA1 is also involved but to a lesser extent. Both transporters are also required for optimum glucose-stimulated insulin secretion, likely via complementary roles. Exogenous cholesterol addition rescues knockdown-induced granule loss (ABCG1) and reduced secretion (both transporters). Another cholesterol transport protein, oxysterol binding protein (OSBP), appears to act proximally as a source of endogenous cholesterol for granule formation. Its knockdown caused similar defective stability of young granules and glucose-stimulated insulin secretion, neither of which were rescued with exogenous cholesterol. Dual knockdowns of OSBP and ABC transporters support their serial function in supplying and concentrating cholesterol for granule formation. OSBP knockdown also decreased proinsulin synthesis consistent with a proximal endoplasmic reticulum defect. Thus, membrane cholesterol distribution contributes to insulin homeostasis at production, packaging, and export levels through the actions of OSBP and ABCs G1 and A1.
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Affiliation(s)
- Syed Saad Hussain
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Megan T Harris
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Alex J B Kreutzberger
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908.,Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Candice M Inouye
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Catherine A Doyle
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Anna M Castle
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Peter Arvan
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, MI 48105
| | - J David Castle
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908.,Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908
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18
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Kwon M, Leem S, Yoon J, Park T. GxGrare: gene-gene interaction analysis method for rare variants from high-throughput sequencing data. BMC SYSTEMS BIOLOGY 2018; 12:19. [PMID: 29560826 PMCID: PMC5861485 DOI: 10.1186/s12918-018-0543-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Background With the rapid advancement of array-based genotyping techniques, genome-wide association studies (GWAS) have successfully identified common genetic variants associated with common complex diseases. However, it has been shown that only a small proportion of the genetic etiology of complex diseases could be explained by the genetic factors identified from GWAS. This missing heritability could possibly be explained by gene-gene interaction (epistasis) and rare variants. There has been an exponential growth of gene-gene interaction analysis for common variants in terms of methodological developments and practical applications. Also, the recent advancement of high-throughput sequencing technologies makes it possible to conduct rare variant analysis. However, little progress has been made in gene-gene interaction analysis for rare variants. Results Here, we propose GxGrare which is a new gene-gene interaction method for the rare variants in the framework of the multifactor dimensionality reduction (MDR) analysis. The proposed method consists of three steps; 1) collapsing the rare variants, 2) MDR analysis for the collapsed rare variants, and 3) detect top candidate interaction pairs. GxGrare can be used for the detection of not only gene-gene interactions, but also interactions within a single gene. The proposed method is illustrated with 1080 whole exome sequencing data of the Korean population in order to identify causal gene-gene interaction for rare variants for type 2 diabetes. Conclusion The proposed GxGrare performs well for gene-gene interaction detection with collapsing of rare variants. GxGrare is available at http://bibs.snu.ac.kr/software/gxgrare which contains simulation data and documentation. Supported operating systems include Linux and OS X. Electronic supplementary material The online version of this article (10.1186/s12918-018-0543-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Minseok Kwon
- Department of Biomedical Informatics, Harvard Medical School, Boston, 02115, MA, USA
| | - Sangseob Leem
- Department of Statistics, Seoul National University, Seoul, 08826, South Korea
| | - Joon Yoon
- Interdisciplinary program, Seoul National University, Seoul, 08826, South Korea
| | - Taesung Park
- Department of Statistics, Seoul National University, Seoul, 08826, South Korea.
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19
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Rorsman P, Ashcroft FM. Pancreatic β-Cell Electrical Activity and Insulin Secretion: Of Mice and Men. Physiol Rev 2018; 98:117-214. [PMID: 29212789 PMCID: PMC5866358 DOI: 10.1152/physrev.00008.2017] [Citation(s) in RCA: 421] [Impact Index Per Article: 70.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/30/2017] [Accepted: 06/18/2017] [Indexed: 12/14/2022] Open
Abstract
The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity, and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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20
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Miyake K, Ohta T, Nakayama H, Doe N, Terao Y, Oiki E, Nagatomo I, Yamashita Y, Abe T, Nishikura K, Kumanogoh A, Hashimoto K, Kawahara Y. CAPS1 RNA Editing Promotes Dense Core Vesicle Exocytosis. Cell Rep 2017; 17:2004-2014. [PMID: 27851964 DOI: 10.1016/j.celrep.2016.10.073] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 10/03/2016] [Accepted: 10/20/2016] [Indexed: 12/20/2022] Open
Abstract
Calcium-dependent activator protein for secretion 1 (CAPS1) plays a distinct role in the priming step of dense core vesicle (DCV) exocytosis. CAPS1 pre-mRNA is known to undergo adenosine-to-inosine RNA editing in its coding region, which results in a glutamate-to-glycine conversion at a site in its C-terminal region. However, the physiological significance of CAPS1 RNA editing remains elusive. Here, we created mutant mice in which edited CAPS1 was solely expressed. These mice were lean due to increased energy expenditure caused by physical hyperactivity. Electrophysiological and biochemical analyses demonstrated that the exocytosis of DCVs was upregulated in the chromaffin cells and neurons of these mice. Furthermore, we showed that edited CAPS1 bound preferentially to the activated form of syntaxin-1A, a component of the exocytotic fusion complex. These findings suggest that RNA editing regulates DCV exocytosis in vivo, affecting physical activity.
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Affiliation(s)
- Kotaro Miyake
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan; Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Toshio Ohta
- Department of Veterinary Pharmacology, Faculty of Agriculture, Tottori University, Tottori, Tottori 680-8553, Japan
| | - Hisako Nakayama
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima 734-8551, Japan
| | - Nobutaka Doe
- General Education Center, Hyogo University of Health Sciences, Kobe, Hyogo 650-8530, Japan
| | - Yuri Terao
- Center for Medical Research and Education, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Eiji Oiki
- Center for Medical Research and Education, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Izumi Nagatomo
- Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yui Yamashita
- Animal Resource Development Unit, RIKEN Center for Life Science Technologies, Kobe, Hyogo 650-0047, Japan; Genetic Engineering Team, RIKEN Center for Life Science Technologies, Kobe, Hyogo 650-0047, Japan
| | - Takaya Abe
- Genetic Engineering Team, RIKEN Center for Life Science Technologies, Kobe, Hyogo 650-0047, Japan
| | | | - Atsushi Kumanogoh
- Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Kouichi Hashimoto
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Hiroshima 734-8551, Japan
| | - Yukio Kawahara
- Department of RNA Biology and Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
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21
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CAPS2 deficiency affects environmental enrichment-induced adult neurogenesis and differentiation/survival of newborn neurons in the hippocampal dentate gyrus. Neurosci Lett 2017; 661:121-125. [PMID: 28963059 DOI: 10.1016/j.neulet.2017.09.047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 09/05/2017] [Accepted: 09/25/2017] [Indexed: 11/23/2022]
Abstract
Hippocampal adult neurogenesis is observed in the subgranular zone of the dentate gyrus (DG), and is associated with hippocampal memory formation and several psychiatric disorders including autism spectrum disorder (ASD). Calcium-dependent activator protein for secretion 2 (CAPS2) is a candidate gene related to ASD, and is highly expressed in the hippocampal DG region, with Caps2 knockout (KO) mice exhibiting ASD-like behavior. Accordingly, CAPS2 is potentially associated with hippocampal adult neurogenesis, the relationship between CAPS2 and adult neurogenesis has not yet been investigated. Here, we determined whether deficit of the Caps2 gene affects hippocampal adult neurogenesis and maturation of newborn neurons. To induce adult neurogenesis, we used the environmental enrichment (EE) condition. Both wild-type (WT) and Caps2 KO mice were housed in control or EE conditions for 3 or 14days. Hippocampal levels of brain-derived neurotrophic factor (BDNF) can be used as a physiological EE conditioned marker, and were increased at 14days in the EE condition in both WT and KO mice. Newborn cells during control and EE conditions were labeled by BrdU, and the labeled cells co-immunostained with the immature and mature neuron markers, calretinin (CR) and NeuN. The ratio of CR/BrdU and NeuN/BrdU double positive cells to all of BrdU positive cells were significantly increased in WT mice housed in the EE condition for 14days compared with the control condition. Whereas KO mice in the EE condition showed no significant increase of newborn neurons. These findings suggest that CAPS2 deficiency strongly impairs hippocampal adult neurogenesis and maturation of newborn neurons.
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22
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Gaisano HY. Recent new insights into the role of SNARE and associated proteins in insulin granule exocytosis. Diabetes Obes Metab 2017; 19 Suppl 1:115-123. [PMID: 28880475 DOI: 10.1111/dom.13001] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 04/23/2017] [Accepted: 05/02/2017] [Indexed: 01/22/2023]
Abstract
Initial work on the exocytotic machinery of predocked insulin secretory granules (SGs) in pancreatic β-cells mimicked the SNARE hypothesis work in neurons, which includes SM/SNARE complex and associated priming proteins, fusion clamps and Ca2+ sensors. However, β-cell SGs, unlike neuronal synaptic vesicles, exhibit a biphasic secretory response that requires additional distinct features in exocytosis including newcomer SGs that undergo minimal docking time at the plasma membrane (PM) before fusion and multi-SG (compound) fusion. These exocytotic events are mediated by Munc18/SNARE complexes distinct from that which mediates predocked SG fusion. We review some recent insights in SNARE complex assembly and the promiscuity in SM/SNARE complex formation, whereby both contribute to conferring different insulin SG fusion kinetics. Some SNARE and associated proteins play non-fusion roles, including tethering SGs to Ca2+ channels, SG recruitment from cell interior to PM, and inhibitory SNAREs that block the action of profusion SNAREs. We discuss new insights into how sub-PM cytoskeletal mesh gates SG access to the PM and the targeting of SG exocytosis to PM domains in functionally polarized β-cells within intact islets. These recent developments have major implications on devising clever SNARE replacement therapies that could restore the deficient insulin secretion in diabetic islet β-cells.
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23
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Abstract
The evolutionary origin of synapses and neurons is an enigmatic subject that inspires much debate. Non-bilaterian metazoans, both with and without neurons and their closest relatives already contain many components of the molecular toolkits for synapse functions. The origin of these components and their assembly into ancient synaptic signaling machineries are particularly important in light of recent findings on the phylogeny of non-bilaterian metazoans. The evolution of synapses and neurons are often discussed only from a metazoan perspective leaving a considerable gap in our understanding. By taking an integrative approach we highlight the need to consider different, but extremely relevant phyla and to include the closest unicellular relatives of metazoans, the ichthyosporeans, filastereans and choanoflagellates, to fully understand the evolutionary origin of synapses and neurons. This approach allows for a detailed understanding of when and how the first pre- and postsynaptic signaling machineries evolved.
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Affiliation(s)
- Pawel Burkhardt
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, United Kingdom
| | - Simon G Sprecher
- Institute of Cell and Developmental Biology, Department of Biology, University of Fribourg, Fribourg, Switzerland
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24
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Rhee JK, Lee JH, Yang HK, Kim TM, Yoon KH. DNA Methylation Profiles of Blood Cells Are Distinct between Early-Onset Obese and Control Individuals. Genomics Inform 2017; 15:28-37. [PMID: 28416947 PMCID: PMC5389946 DOI: 10.5808/gi.2017.15.1.28] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 01/25/2017] [Accepted: 02/10/2017] [Indexed: 01/30/2023] Open
Abstract
Obesity is a highly prevalent, chronic disorder that has been increasing in incidence in young patients. Both epigenetic and genetic aberrations may play a role in the pathogenesis of obesity. Therefore, in-depth epigenomic and genomic analyses will advance our understanding of the detailed molecular mechanisms underlying obesity and aid in the selection of potential biomarkers for obesity in youth. Here, we performed microarray-based DNA methylation and gene expression profiling of peripheral white blood cells obtained from six young, obese individuals and six healthy controls. We observed that the hierarchical clustering of DNA methylation, but not gene expression, clearly segregates the obese individuals from the controls, suggesting that the metabolic disturbance that occurs as a result of obesity at a young age may affect the DNA methylation of peripheral blood cells without accompanying transcriptional changes. To examine the genome-wide differences in the DNA methylation profiles of young obese and control individuals, we identified differentially methylated CpG sites and investigated their genomic and epigenomic contexts. The aberrant DNA methylation patterns in obese individuals can be summarized as relative gains and losses of DNA methylation in gene promoters and gene bodies, respectively. We also observed that the CpG islands of obese individuals are more susceptible to DNA methylation compared to controls. Our pilot study suggests that the genome-wide aberrant DNA methylation patterns of obese individuals may advance not only our understanding of the epigenomic pathogenesis but also early screening of obesity in youth.
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Affiliation(s)
- Je-Keun Rhee
- Department of Medical Informatics, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Jin-Hee Lee
- Catholic Institute of U-Healthcare, Institute of Biomedical Industry, The Catholic University of Korea, Seoul 06591, Korea
| | - Hae Kyung Yang
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Tae-Min Kim
- Department of Medical Informatics, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Kun-Ho Yoon
- Department of Medical Informatics, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.,Catholic Institute of U-Healthcare, Institute of Biomedical Industry, The Catholic University of Korea, Seoul 06591, Korea.,Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
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25
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Analysis of gene expression in Ca2+-dependent activator protein for secretion 2 (Cadps2) knockout cerebellum using GeneChip and KEGG pathways. Neurosci Lett 2017; 639:88-93. [DOI: 10.1016/j.neulet.2016.12.068] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/09/2016] [Accepted: 12/28/2016] [Indexed: 11/20/2022]
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26
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Shinoda Y, Ishii C, Fukazawa Y, Sadakata T, Ishii Y, Sano Y, Iwasato T, Itohara S, Furuichi T. CAPS1 stabilizes the state of readily releasable synaptic vesicles to fusion competence at CA3-CA1 synapses in adult hippocampus. Sci Rep 2016; 6:31540. [PMID: 27545744 PMCID: PMC4992871 DOI: 10.1038/srep31540] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 07/21/2016] [Indexed: 01/06/2023] Open
Abstract
Calcium-dependent activator protein for secretion 1 (CAPS1) regulates exocytosis of dense-core vesicles in neuroendocrine cells and of synaptic vesicles in neurons. However, the synaptic function of CAPS1 in the mature brain is unclear because Caps1 knockout (KO) results in neonatal death. Here, using forebrain-specific Caps1 conditional KO (cKO) mice, we demonstrate, for the first time, a critical role of CAPS1 in adult synapses. The amplitude of synaptic transmission at CA3–CA1 synapses was strongly reduced, and paired-pulse facilitation was significantly increased, in acute hippocampal slices from cKO mice compared with control mice, suggesting a perturbation in presynaptic function. Morphological analysis revealed an accumulation of synaptic vesicles in the presynapse without any overall morphological change. Interestingly, however, the percentage of docked vesicles was markedly decreased in the Caps1 cKO. Taken together, our findings suggest that CAPS1 stabilizes the state of readily releasable synaptic vesicles, thereby enhancing neurotransmitter release at hippocampal synapses.
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Affiliation(s)
- Yo Shinoda
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba 278-8510, Japan.,School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Chiaki Ishii
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Yugo Fukazawa
- Department of Brain Structure and Function, Faculty of Medical Sciences, University of Fukui, Yoshida-gun, Fukui 910-1193, Japan
| | - Tetsushi Sadakata
- Advanced Scientific Research Leaders Development Unit, Gunma University, Maebashi, Gunma 371-8511, Japan
| | - Yuki Ishii
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Yoshitake Sano
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Takuji Iwasato
- Division of Neurogenetics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
| | - Shigeyoshi Itohara
- Laboratory for Behavioral Genetics, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Teiichi Furuichi
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba 278-8510, Japan
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27
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Abstract
High-resolution deep tissue imaging is possible with two-photon excitation microscopy. With the combined application of two-photon imaging and perfusion with a polar fluorescent tracer, we have established a method to detect exocytic events inside secretory tissues. This method displays the spatiotemporal distribution of exocytic sites, dynamics of fusion pores, and modes of exocytosis. In glucose-stimulated pancreatic islets, exocytic events were observed to be synchronized with an increase in cytosolic Ca(2+) concentrations. Full fusion of a single secretory granule is the typical mode of exocytosis and compound exocytosis is inhibited. Because two-photon excitation enables simultaneous multicolor imaging due to the broadened excitation spectra, the distributions and conformational changes in fluorescent-labeled molecules can be simultaneously visualized with exocytic events. Therefore, we can analyze the dynamics of the molecules involved in membrane fusion and their association with exocytosis in living tissues.
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Affiliation(s)
- Noriko Takahashi
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo
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28
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Interaction of Ca(2+)-dependent activator protein for secretion 1 (CAPS1) with septin family proteins in mouse brain. Neurosci Lett 2016; 617:232-5. [PMID: 26917099 DOI: 10.1016/j.neulet.2016.02.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/18/2016] [Accepted: 02/19/2016] [Indexed: 01/22/2023]
Abstract
The Ca(2+)-dependent activator protein for secretion 1 (CAPS1) protein plays a regulatory role in the dense-core vesicle exocytosis pathway. To clarify the functions of this protein in the brain, we searched for novel interaction partners of CAPS1 by mass spectrometry. We identified a specific interaction of CAPS1 with septin family proteins. We also demonstrated that the C-terminal region of the CAPS1 protein binds to part of the deduced GTP-binding domain of septin proteins. It is possible that a tertiary complex of septin, CAPS, and syntaxin contributes to dense-core vesicle trafficking and exocytosis in neurons.
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29
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Kabachinski G, Kielar-Grevstad DM, Zhang X, James DJ, Martin TFJ. Resident CAPS on dense-core vesicles docks and primes vesicles for fusion. Mol Biol Cell 2016; 27:654-68. [PMID: 26700319 PMCID: PMC4750925 DOI: 10.1091/mbc.e15-07-0509] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 12/12/2015] [Accepted: 12/18/2015] [Indexed: 11/11/2022] Open
Abstract
The Ca(2+)-dependent exocytosis of dense-core vesicles in neuroendocrine cells requires a priming step during which SNARE protein complexes assemble. CAPS (aka CADPS) is one of several factors required for vesicle priming; however, the localization and dynamics of CAPS at sites of exocytosis in live neuroendocrine cells has not been determined. We imaged CAPS before, during, and after single-vesicle fusion events in PC12 cells by TIRF micro-scopy. In addition to being a resident on cytoplasmic dense-core vesicles, CAPS was present in clusters of approximately nine molecules near the plasma membrane that corresponded to docked/tethered vesicles. CAPS accompanied vesicles to the plasma membrane and was present at all vesicle exocytic events. The knockdown of CAPS by shRNA eliminated the VAMP-2-dependent docking and evoked exocytosis of fusion-competent vesicles. A CAPS(ΔC135) protein that does not localize to vesicles failed to rescue vesicle docking and evoked exocytosis in CAPS-depleted cells, showing that CAPS residence on vesicles is essential. Our results indicate that dense-core vesicles carry CAPS to sites of exocytosis, where CAPS promotes vesicle docking and fusion competence, probably by initiating SNARE complex assembly.
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Affiliation(s)
- Greg Kabachinski
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706
| | | | - Xingmin Zhang
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706
| | - Declan J James
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706
| | - Thomas F J Martin
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706
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30
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Eckenstaler R, Lessmann V, Brigadski T. CAPS1 effects on intragranular pH and regulation of BDNF release from secretory granules in hippocampal neurons. J Cell Sci 2016; 129:1378-90. [PMID: 26869227 DOI: 10.1242/jcs.178251] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 02/08/2016] [Indexed: 01/19/2023] Open
Abstract
The secretory protein brain-derived neurotrophic factor (BDNF) is assumed to be a key factor for the induction of synaptic plasticity processes in neurons. However, the molecular mechanisms for activity-dependent release of the protein largely remain elusive. Here, we demonstrate the relevance of the priming factor CAPS1 (also known as CADPS) for the maturation and exocytosis of BDNF-containing secretory granules, as well as for neurotransmitter release from synaptic vesicles. Using live-cell imaging and RNA silencing methods, we show that CAPS1 has a previously unrecognized function in regulating the intragranular pH of BDNF-containing secretory granules. Furthermore, our results demonstrate that acute single-cell knockdown of CAPS1 with unaltered expression in neighboring neurons leads to a strong reduction in the number of fusion-competent secretory granules and to a significant decrease of released BDNF following exocytosis in dendrites of CAPS1-deficient neurons. In addition, our results show a reduction in synaptic vesicle turnover after CAPS1 knockdown without affecting the density of active boutons in hippocampal neurons. Thus, our results reveal new functions of endogenous CAPS1 in the BDNF secretory granule life cycle, thereby representing a new mechanism of neuronal plasticity.
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Affiliation(s)
- Robert Eckenstaler
- Institute of Physiology, Medical Faculty, Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Volkmar Lessmann
- Institute of Physiology, Medical Faculty, Otto-von-Guericke-University, Magdeburg 39120, Germany Center of Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany
| | - Tanja Brigadski
- Institute of Physiology, Medical Faculty, Otto-von-Guericke-University, Magdeburg 39120, Germany Center of Behavioral Brain Sciences (CBBS), Magdeburg 39120, Germany
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31
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Shaheen R, Patel N, Shamseldin H, Alzahrani F, Al-Yamany R, ALMoisheer A, Ewida N, Anazi S, Alnemer M, Elsheikh M, Alfaleh K, Alshammari M, Alhashem A, Alangari AA, Salih MA, Kircher M, Daza RM, Ibrahim N, Wakil SM, Alaqeel A, Altowaijri I, Shendure J, Al-Habib A, Faqieh E, Alkuraya FS. Accelerating matchmaking of novel dysmorphology syndromes through clinical and genomic characterization of a large cohort. Genet Med 2015; 18:686-95. [PMID: 26633546 DOI: 10.1038/gim.2015.147] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 09/03/2015] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Dysmorphology syndromes are among the most common referrals to clinical genetics specialists. Inability to match the dysmorphology pattern to a known syndrome can pose a major diagnostic challenge. With an aim to accelerate the establishment of new syndromes and their genetic etiology, we describe our experience with multiplex consanguineous families that appeared to represent novel autosomal recessive dysmorphology syndromes at the time of evaluation. METHODS Combined autozygome/exome analysis of multiplex consanguineous families with apparently novel dysmorphology syndromes. RESULTS Consistent with the apparent novelty of the phenotypes, our analysis revealed a strong candidate variant in genes that were novel at the time of the analysis in the majority of cases, and 10 of these genes are published here for the first time as novel candidates (CDK9, NEK9, ZNF668, TTC28, MBL2, CADPS, CACNA1H, HYAL2, CTU2, and C3ORF17). A significant minority of the phenotypes (6/31, 19%), however, were caused by genes known to cause Mendelian phenotypes, thus expanding the phenotypic spectrum of the diseases linked to these genes. The conspicuous inheritance pattern and the highly specific phenotypes appear to have contributed to the high yield (90%) of plausible molecular diagnoses in our study cohort. CONCLUSION Reporting detailed clinical and genomic analysis of a large series of apparently novel dysmorphology syndromes will likely lead to a trend to accelerate the establishment of novel syndromes and their underlying genes through open exchange of data for the benefit of patients, their families, health-care providers, and the research community.Genet Med 18 7, 686-695.
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Affiliation(s)
- Ranad Shaheen
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Nisha Patel
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Hanan Shamseldin
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Fatema Alzahrani
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Ruah Al-Yamany
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Agaadir ALMoisheer
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Nour Ewida
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Shamsa Anazi
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Maha Alnemer
- Department of Obstetrics and Gynecology, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Mohamed Elsheikh
- Department of Obstetrics and Gynecology, Suliman AlHabib Hospital, Riyadh, Saudi Arabia
| | - Khaled Alfaleh
- Department of Obstetrics and Gynecology, Suliman AlHabib Hospital, Riyadh, Saudi Arabia.,Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Muneera Alshammari
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Amal Alhashem
- Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - Abdullah A Alangari
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Mustafa A Salih
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Martin Kircher
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Riza M Daza
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Niema Ibrahim
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Salma M Wakil
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Ahmed Alaqeel
- Department of Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Ikhlas Altowaijri
- Department of Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, Washington, USA
| | - Amro Al-Habib
- Department of Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Eissa Faqieh
- Department of Pediatrics, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
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32
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Man KNM, Imig C, Walter AM, Pinheiro PS, Stevens DR, Rettig J, Sørensen JB, Cooper BH, Brose N, Wojcik SM. Identification of a Munc13-sensitive step in chromaffin cell large dense-core vesicle exocytosis. eLife 2015; 4. [PMID: 26575293 PMCID: PMC4798968 DOI: 10.7554/elife.10635] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/16/2015] [Indexed: 01/16/2023] Open
Abstract
It is currently unknown whether the molecular steps of large dense-core vesicle (LDCV) docking and priming are identical to the corresponding reactions in synaptic vesicle (SV) exocytosis. Munc13s are essential for SV docking and priming, and we systematically analyzed their role in LDCV exocytosis using chromaffin cells lacking individual isoforms. We show that particularly Munc13-2 plays a fundamental role in LDCV exocytosis, but in contrast to synapses lacking Munc13s, the corresponding chromaffin cells do not exhibit a vesicle docking defect. We further demonstrate that ubMunc13-2 and Munc13-1 confer Ca(2+)-dependent LDCV priming with similar affinities, but distinct kinetics. Using a mathematical model, we identify an early LDCV priming step that is strongly dependent upon Munc13s. Our data demonstrate that the molecular steps of SV and LDCV priming are very similar while SV and LDCV docking mechanisms are distinct.
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Affiliation(s)
- Kwun Nok M Man
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | | | - Paulo S Pinheiro
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences and Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - David R Stevens
- Department of Physiology, Saarland University, Homburg, Germany
| | - Jens Rettig
- Department of Physiology, Saarland University, Homburg, Germany
| | - Jakob B Sørensen
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences and Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark
| | - Benjamin H Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Sonja M Wojcik
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
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33
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Lack of stress responses to long-term effects of corticosterone in Caps2 knockout mice. Sci Rep 2015; 5:8932. [PMID: 25754523 PMCID: PMC4354153 DOI: 10.1038/srep08932] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 02/11/2015] [Indexed: 11/08/2022] Open
Abstract
Chronic stress is associated with anxiety and depressive disorders, and can cause weight gain. Ca(2+)-dependent activator protein for secretion 2 (CAPS2) is involved in insulin release. Caps2 knockout (KO) mice exhibit decreased body weight, reduced glucose-induced insulin release, and abnormal psychiatric behaviors. We chronically administered the stress hormone corticosterone (CORT), which induces anxiety/depressive-like behavior and normally increases plasma insulin levels, via the drinking water for 10 weeks, and we examined the stress response in KO mice. Chronic CORT exposure inhibited stress-induced serum CORT elevation in wild-type (WT) mice, but not in KO mice. Poor weight gain in CORT-treated animals was observed until week 6 in WT mice, but persisted for the entire duration of the experiment in KO mice, although there is no difference in drug*genotype interaction. Among KO mice, food consumption was unchanged, while water consumption was higher, over the duration of the experiment in CORT-treated animals, compared with untreated animals. Moreover, serum insulin and leptin levels were increased in CORT-treated WT mice, but not in KO mice. Lastly, both WT and KO mice displayed anxiety/depressive-like behavior after CORT administration. These results suggest that Caps2 KO mice have altered endocrine responses to CORT administration, while maintaining CORT-induced anxiety/depressive-like behavior.
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34
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Wuttke A. Lipid Signalling Dynamics at the β-cell Plasma Membrane. Basic Clin Pharmacol Toxicol 2015; 116:281-90. [DOI: 10.1111/bcpt.12369] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 12/15/2014] [Indexed: 12/26/2022]
Affiliation(s)
- Anne Wuttke
- Department of Medical Cell Biology; Uppsala University; Uppsala Sweden
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35
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Nemoto T, Toyoshima-Aoyama F, Yanagita T, Maruta T, Fujita H, Koshida T, Yonaha T, Wada A, Sawaguchi A, Murakami M. New insights concerning insulin synthesis and its secretion in rat hippocampus and cerebral cortex: Amyloid-β1–42-induced reduction of proinsulin level via glycogen synthase kinase-3β. Cell Signal 2014; 26:253-9. [DOI: 10.1016/j.cellsig.2013.11.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 11/14/2013] [Indexed: 12/20/2022]
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36
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CAPS1 deficiency perturbs dense-core vesicle trafficking and Golgi structure and reduces presynaptic release probability in the mouse brain. J Neurosci 2013; 33:17326-34. [PMID: 24174665 DOI: 10.1523/jneurosci.2777-13.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ca(2+)-dependent activator protein for secretion 1 (CAPS1) plays a regulatory role in the dense-core vesicle (DCV) exocytosis pathway, but its functions at the cellular and synaptic levels in the brain are essentially unknown because of neonatal death soon after birth in Caps1 knock-out mice. To clarify the functions of the protein in the brain, we generated two conditional knock-out (cKO) mouse lines: 1) one lacking Caps1 in the forebrain; and 2) the other lacking Caps1 in the cerebellum. Both cKO mouse lines were born normally and grew to adulthood, although they showed subcellular and synaptic abnormalities. Forebrain-specific Caps1 cKO mice showed reduced immunoreactivity for the DCV marker secretogranin II (SgII) and the trans-Golgi network (TGN) marker syntaxin 6, a reduced number of presynaptic DCVs, and dilated trans-Golgi cisternae in the CA3 region. Cerebellum-specific Caps1 cKO mice had decreased immunoreactivity for SgII and brain-derived neurotrophic factor (BDNF) along the climbing fibers. At climbing fiber-Purkinje cell synapses, the number of DCVs was markedly lower and the number of synaptic vesicles was also reduced. Correspondingly, the mean amplitude of EPSCs was decreased, whereas paired-pulse depression was significantly increased. Our results suggest that loss of CAPS1 disrupts the TGN-DCV pathway, which possibly impairs synaptic transmission by reducing the presynaptic release probability.
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37
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James DJ, Martin TFJ. CAPS and Munc13: CATCHRs that SNARE Vesicles. Front Endocrinol (Lausanne) 2013; 4:187. [PMID: 24363652 PMCID: PMC3849599 DOI: 10.3389/fendo.2013.00187] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 11/18/2013] [Indexed: 11/13/2022] Open
Abstract
CAPS (Calcium-dependent Activator Protein for Secretion, aka CADPS) and Munc13 (Mammalian Unc-13) proteins function to prime vesicles for Ca(2+)-triggered exocytosis in neurons and neuroendocrine cells. CAPS and Munc13 proteins contain conserved C-terminal domains that promote the assembly of SNARE complexes for vesicle priming. Similarities of the C-terminal domains of CAPS/Munc13 proteins with Complex Associated with Tethering Containing Helical Rods domains in multi-subunit tethering complexes (MTCs) have been reported. MTCs coordinate multiple interactions for SNARE complex assembly at constitutive membrane fusion steps. We review aspects of these diverse tethering and priming factors to identify common operating principles.
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Affiliation(s)
- Declan J. James
- Department of Biochemistry, University of Wisconsin, Madison, WI, USA
| | - Thomas F. J. Martin
- Department of Biochemistry, University of Wisconsin, Madison, WI, USA
- *Correspondence: Thomas F. J. Martin, Department of Biochemistry, University of Wisconsin, 433 Babcock Drive, Madison, WI 53706, USA e-mail:
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38
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Parsaud L, Li L, Jung CH, Park S, Saw NMN, Park S, Kim MY, Sugita S. Calcium-dependent activator protein for secretion 1 (CAPS1) binds to syntaxin-1 in a distinct mode from Munc13-1. J Biol Chem 2013; 288:23050-63. [PMID: 23801330 DOI: 10.1074/jbc.m113.494088] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calcium-dependent activator protein for secretion 1 (CAPS1) is a multidomain protein containing a Munc13 homology domain 1 (MHD1). Although CAPS1 and Munc13-1 play crucial roles in the priming stage of secretion, their functions are non-redundant. Similar to Munc13-1, CAPS1 binds to syntaxin-1, a key t-SNARE protein in neurosecretion. However, whether CAPS1 interacts with syntaxin-1 in a similar mode to Munc13-1 remains unclear. Here, using yeast two-hybrid assays followed by biochemical binding experiments, we show that the region in CAPS1 consisting of the C-terminal half of the MHD1 with the corresponding C-terminal region can bind to syntaxin-1. Importantly, the binding mode of CAPS1 to syntaxin-1 is distinct from that of Munc13-1; CAPS1 binds to the full-length of cytoplasmic syntaxin-1 with preference to its "open" conformation, whereas Munc13-1 binds to the first 80 N-terminal residues of syntaxin-1. Unexpectedly, the majority of the MHD1 of CAPS1 is dispensable, whereas the C-terminal 69 residues are crucial for the binding to syntaxin-1. Functionally, a C-terminal truncation of 69 or 134 residues in CAPS1 abolishes its ability to reconstitute secretion in permeabilized PC12 cells. Our results reveal a novel mode of binding between CAPS1 and syntaxin-1, which play a crucial role in neurosecretion. We suggest that the distinct binding modes between CAPS1 and Munc13-1 can account for their non-redundant functions in neurosecretion. We also propose that the preferential binding of CAPS1 to open syntaxin-1 can contribute to the stabilization of the open state of syntaxin-1 during its transition from "closed" state to the SNARE complex formation.
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Affiliation(s)
- Leon Parsaud
- Division of Fundamental Neurobiology, University Health Network, Toronto, Ontario M5T 2S8, Canada
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Kasai H, Takahashi N, Tokumaru H. Distinct Initial SNARE Configurations Underlying the Diversity of Exocytosis. Physiol Rev 2012; 92:1915-64. [DOI: 10.1152/physrev.00007.2012] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The dynamics of exocytosis are diverse and have been optimized for the functions of synapses and a wide variety of cell types. For example, the kinetics of exocytosis varies by more than five orders of magnitude between ultrafast exocytosis in synaptic vesicles and slow exocytosis in large dense-core vesicles. However, in all cases, exocytosis is mediated by the same fundamental mechanism, i.e., the assembly of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. It is often assumed that vesicles need to be docked at the plasma membrane and SNARE proteins must be preassembled before exocytosis is triggered. However, this model cannot account for the dynamics of exocytosis recently reported in synapses and other cells. For example, vesicles undergo exocytosis without prestimulus docking during tonic exocytosis of synaptic vesicles in the active zone. In addition, epithelial and hematopoietic cells utilize cAMP and kinases to trigger slow exocytosis of nondocked vesicles. In this review, we summarize the manner in which the diversity of exocytosis reflects the initial configurations of SNARE assembly, including trans-SNARE, binary-SNARE, unitary-SNARE, and cis-SNARE configurations. The initial SNARE configurations depend on the particular SNARE subtype (syntaxin, SNAP25, or VAMP), priming proteins (Munc18, Munc13, CAPS, complexin, or snapin), triggering proteins (synaptotagmins, Doc2, and various protein kinases), and the submembraneous cytomatrix, and they are the key to determining the kinetics of subsequent exocytosis. These distinct initial configurations will help us clarify the common SNARE assembly processes underlying exocytosis and membrane trafficking in eukaryotic cells.
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Affiliation(s)
- Haruo Kasai
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; and Faculty of Pharmaceutical Sciences at Kagawa, Tokushima Bunri University, Kagawa, Japan
| | - Noriko Takahashi
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; and Faculty of Pharmaceutical Sciences at Kagawa, Tokushima Bunri University, Kagawa, Japan
| | - Hiroshi Tokumaru
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; and Faculty of Pharmaceutical Sciences at Kagawa, Tokushima Bunri University, Kagawa, Japan
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Multiple roles for the actin cytoskeleton during regulated exocytosis. Cell Mol Life Sci 2012; 70:2099-121. [PMID: 22986507 DOI: 10.1007/s00018-012-1156-5] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/28/2012] [Accepted: 08/30/2012] [Indexed: 01/01/2023]
Abstract
Regulated exocytosis is the main mechanism utilized by specialized secretory cells to deliver molecules to the cell surface by virtue of membranous containers (i.e., secretory vesicles). The process involves a series of highly coordinated and sequential steps, which include the biogenesis of the vesicles, their delivery to the cell periphery, their fusion with the plasma membrane, and the release of their content into the extracellular space. Each of these steps is regulated by the actin cytoskeleton. In this review, we summarize the current knowledge regarding the involvement of actin and its associated molecules during each of the exocytic steps in vertebrates, and suggest that the overall role of the actin cytoskeleton during regulated exocytosis is linked to the architecture and the physiology of the secretory cells under examination. Specifically, in neurons, neuroendocrine, endocrine, and hematopoietic cells, which contain small secretory vesicles that undergo rapid exocytosis (on the order of milliseconds), the actin cytoskeleton plays a role in pre-fusion events, where it acts primarily as a functional barrier and facilitates docking. In exocrine and other secretory cells, which contain large secretory vesicles that undergo slow exocytosis (seconds to minutes), the actin cytoskeleton plays a role in post-fusion events, where it regulates the dynamics of the fusion pore, facilitates the integration of the vesicles into the plasma membrane, provides structural support, and promotes the expulsion of large cargo molecules.
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Fedjaev M, Parmar A, Xu Y, Vyetrogon K, Difalco MR, Ashmarina M, Nifant'ev I, Posner BI, Pshezhetsky AV. Global analysis of protein phosphorylation networks in insulin signaling by sequential enrichment of phosphoproteins and phosphopeptides. MOLECULAR BIOSYSTEMS 2012; 8:1461-71. [PMID: 22362066 DOI: 10.1039/c2mb05440j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Although the important role of protein phosphorylation in insulin signaling networks is well recognized, its analysis in vivo has not been pursued in a systematic fashion through proteome-wide studies. Here we undertake a global analysis of insulin-induced changes in the rat liver cytoplasmic and endosomal phosphoproteome by sequential enrichment of phosphoproteins and phosphopeptides. After subcellular fractionation proteins were denatured and loaded onto iminodiacetic acid-modified Sepharose with immobilized Al³⁺ ions (IMAC-Al resin). Retained phosphoproteins were eluted with 50 mM phosphate and proteolytically digested. The digest was then loaded onto an IMAC-Al resin and phosphopeptides were eluted with 50 mM phosphate, and resolved by 2-dimensional liquid chromatography, which combined offline weak anion exchange and online reverse phase separations. The peptides were identified by tandem mass spectrometry, which also detected the phosphorylation sites. Non-phosphorylated peptides found in the flow-through of the IMAC-Al columns were also analyzed providing complementary information for protein identification. In this study we enriched phosphopeptides to ~85% purity and identified 1456 phosphopeptides from 604 liver phosphoproteins. Eighty-nine phosphosites including 45 novel ones in 83 proteins involved in vesicular transport, metabolism, cell motility and structure, gene expression and various signaling pathways were changed in response to insulin treatment. Together these findings could provide potential new markers for evaluating insulin action and resistance in obesity and diabetes.
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Affiliation(s)
- Michael Fedjaev
- Department of Medical Genetics, CHU Sainte-Justine, University of Montreal, Montreal, Quebec H3T 1C5, Canada
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Cai T, Hirai H, Zhang G, Zhang M, Takahashi N, Kasai H, Satin LS, Leapman RD, Notkins AL. Deletion of Ia-2 and/or Ia-2β in mice decreases insulin secretion by reducing the number of dense core vesicles. Diabetologia 2011; 54:2347-57. [PMID: 21732083 PMCID: PMC3168514 DOI: 10.1007/s00125-011-2221-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 05/23/2011] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Islet antigen 2 (IA-2) and IA-2β are dense core vesicle (DCV) transmembrane proteins and major autoantigens in type 1 diabetes. The present experiments were initiated to test the hypothesis that the knockout of the genes encoding these proteins impairs the secretion of insulin by reducing the number of DCV. METHODS Insulin secretion, content and DCV number were evaluated in islets from single knockout (Ia-2 [also known as Ptprn] KO, Ia-2β [also known as Ptprn2] KO) and double knockout (DKO) mice by a variety of techniques including electron and two-photon microscopy, membrane capacitance, Ca(2+) currents, DCV half-life, lysosome number and size and autophagy. RESULTS Islets from single and DKO mice all showed a significant decrease in insulin content, insulin secretion and the number and half-life of DCV (p < 0.05 to 0.001). Exocytosis as evaluated by two-photon microscopy, membrane capacitance and Ca(2+) currents supports these findings. Electron microscopy of islets from KO mice revealed a marked increase (p < 0.05 to 0.001) in the number and size of lysosomes and enzymatic studies showed an increase in cathepsin D activity (p < 0.01). LC3 protein, an indicator of autophagy, also was increased in islets of KO compared with wild-type mice (p < 0.05 to 0.01) suggesting that autophagy might be involved in the deletion of DCV. CONCLUSIONS/INTERPRETATION We conclude that the decrease in insulin content and secretion, resulting from the deletion of Ia-2 and/or Ia-2β, is due to a decrease in the number of DCV.
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Affiliation(s)
- T. Cai
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA
- Correspondences: T. Cai: OIIB, NIDCR/NIH, Bethesda, MD 20892, USA Tel: 301-402-5320; Fax: 301-402-4163; ; Or A. Notkins: EMS, OIIB, NIDCR/NIH, Bethesda, MD 20892, USA Tel: 301-496-4535; Fax: 301-402-4163;
| | - H. Hirai
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA
| | - G. Zhang
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, Maryland 20892, USA
| | - M. Zhang
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - N. Takahashi
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-Ku, Tokyo, 113-0033, Japan
| | - H. Kasai
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-Ku, Tokyo, 113-0033, Japan
| | - L. S. Satin
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
- Department of Pharmacology and Brehm Diabetes Center, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - R. D. Leapman
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, Maryland 20892, USA
| | - A. L. Notkins
- Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA
- Correspondences: T. Cai: OIIB, NIDCR/NIH, Bethesda, MD 20892, USA Tel: 301-402-5320; Fax: 301-402-4163; ; Or A. Notkins: EMS, OIIB, NIDCR/NIH, Bethesda, MD 20892, USA Tel: 301-496-4535; Fax: 301-402-4163;
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Khodthong C, Kabachinski G, James DJ, Martin TFJ. Munc13 homology domain-1 in CAPS/UNC31 mediates SNARE binding required for priming vesicle exocytosis. Cell Metab 2011; 14:254-63. [PMID: 21803295 PMCID: PMC3148490 DOI: 10.1016/j.cmet.2011.07.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 04/09/2011] [Accepted: 06/21/2011] [Indexed: 01/11/2023]
Abstract
Neuropeptide and peptide hormone secretion from neural and endocrine cells occurs by Ca(2+)-triggered dense-core vesicle exocytosis. The membrane fusion machinery consisting of vesicle and plasma membrane SNARE proteins needs to be assembled for Ca(2+)-triggered vesicle exocytosis. The related Munc13 and CAPS/UNC31 proteins that prime vesicle exocytosis are proposed to promote SNARE complex assembly. CAPS binds SNARE proteins and stimulates SNARE complex formation on liposomes, but the relevance of SNARE binding to CAPS function in cells had not been determined. Here we identify a core SNARE-binding domain in CAPS as corresponding to Munc13 homology domain-1 (MHD1). CAPS lacking a single helix in MHD1 was unable to bind SNARE proteins or to support the Ca(2+)-triggered exocytosis of either docked or newly arrived dense-core vesicles. The results show that MHD1 is a SNARE-binding domain and that SNARE protein binding is essential for CAPS function in dense-core vesicle exocytosis.
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Cape A, Chen X, Wang CE, O'Neill A, Lin YF, He J, Xu XS, Yi H, Li H, Li S, Li XJ. Loss of huntingtin-associated protein 1 impairs insulin secretion from pancreatic β-cells. Cell Mol Life Sci 2011; 69:1305-17. [PMID: 21544547 DOI: 10.1007/s00018-011-0692-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/25/2011] [Accepted: 04/14/2011] [Indexed: 12/23/2022]
Abstract
Hap1 was originally identified as a neuronal protein that interacts with huntingtin, the Huntington's disease (HD) protein. Later studies revealed that Hap1 participates in intracellular trafficking in neuronal cells and that this trafficking function can be adversely affected by mutant huntingtin. Hap1 is also present in pancreatic β-cells and other endocrine cells; however, the role of Hap1 in these endocrine cells remains unknown. Using the Cre-loxP system, we generated conditional Hap1 knockout mice to selectively deplete the expression of Hap1 in mouse pancreatic β-cells. Mutant mice with Hap1 deficiency in pancreatic β-cells had impaired glucose tolerance and decreased insulin release in response to intraperitoneally injected glucose. Using cultured pancreatic β-cell lines and isolated mouse pancreatic islets, we confirmed that decreasing Hap1 could reduce glucose-mediated insulin release. Electron microscopy suggested that there was a reduced number of insulin-containing vesicles docked at the plasma membrane of pancreatic islets in Hap1 mutant mice following intraperitoneal glucose injection. Glucose treatment decreased the phosphorylation of Hap1A in cultured β-cells and in mouse pancreatic tissues. Moreover, this glucose treatment increased Hap1's association with kinesin light chain and dynactin p150, both of which are involved in microtubule-dependent trafficking. These studies suggest that Hap1 is important for insulin release from β-cells via dephosphorylation that can regulate its intracellular trafficking function.
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Affiliation(s)
- Austin Cape
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
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Furuichi T, Shiraishi-Yamaguchi Y, Sato A, Sadakata T, Huang J, Shinoda Y, Hayashi K, Mishima Y, Tomomura M, Nishibe H, Yoshikawa F. Systematizing and cloning of genes involved in the cerebellar cortex circuit development. Neurochem Res 2011; 36:1241-52. [PMID: 21243430 DOI: 10.1007/s11064-011-0398-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2011] [Indexed: 10/18/2022]
Abstract
The cerebellar cortical circuit of mammals develops via a series of magnificent cellular events in the postnatal stage of development to accomplish the formation of functional circuit architectures. The contribution of genetic factors is thought to be crucial to cerebellar development. Therefore, it is essential to analyze the underlying transcriptome during development to understand the genetic blueprint of the cerebellar cortical circuit. In this review, we introduce the profiling of large numbers of spatiotemporal gene expression data obtained by developmental time-series microarray analyses and in situ hybridization cellular mRNA mapping, and the creation of a neuroinformatics database called the Cerebellar Development Transcriptome Database. Using this database, we have identified thousands of genes that are classified into various functional categories and are expressed coincidently with related cellular developmental stages. We have also suggested the molecular mechanisms of cerebellar development by functional characterization of several identified genes (Cupidin, p130Cas, very-KIND, CAPS2) responsible for distinct cellular events of developing cerebellar granule cells. Taken together, the gene expression profiling during the cerebellar development demonstrates that the development of cerebellar cortical circuit is attributed to the complex but orchestrated transcriptome.
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Affiliation(s)
- Teiichi Furuichi
- Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, 351-0198, Saitama, Japan.
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Sadakata T, Shinoda Y, Sekine Y, Saruta C, Itakura M, Takahashi M, Furuichi T. Interaction of calcium-dependent activator protein for secretion 1 (CAPS1) with the class II ADP-ribosylation factor small GTPases is required for dense-core vesicle trafficking in the trans-Golgi network. J Biol Chem 2010; 285:38710-9. [PMID: 20921225 PMCID: PMC2992304 DOI: 10.1074/jbc.m110.137414] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 09/30/2010] [Indexed: 11/06/2022] Open
Abstract
Ca(2+)-dependent activator protein for secretion (CAPS) regulates exocytosis of catecholamine- or neuropeptide-containing dense-core vesicles (DCVs) at secretion sites, such as nerve terminals. However, large amounts of CAPS protein are localized in the cell soma, and the role of somal CAPS protein remains unclear. The present study shows that somal CAPS1 plays an important role in DCV trafficking in the trans-Golgi network. The anti-CAPS1 antibody appeared to pull down membrane fractions, including many Golgi-associated proteins, such as ADP-ribosylation factor (ARF) small GTPases. Biochemical analyses of the protein-protein interaction showed that CAPS1 interacted specifically with the class II ARF4/ARF5, but not with other classes of ARFs, via the pleckstrin homology domain in a GDP-bound ARF form-specific manner. The pleckstrin homology domain of CAPS1 showed high affinity for the Golgi membrane, thereby recruiting ARF4/ARF5 to the Golgi complex. Knockdown of either CAPS1 or ARF4/ARF5 expression caused accumulation of chromogranin, a DCV marker protein, in the Golgi, thereby reducing its DCV secretion. In addition, the overexpression of CAPS1 binding-deficient ARF5 mutants induced aberrant chromogranin accumulation in the Golgi and consequently reduced its DCV secretion. These findings implicate a functional role for CAPS1 protein in the soma, a major subcellular localization site of CAPS1 in many cell types, in regulating DCV trafficking in the trans-Golgi network; this activity occurs via protein-protein interaction with ARF4/ARF5 in a GDP-dependent manner.
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Affiliation(s)
- Tetsushi Sadakata
- From the Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
- Japan Science and Technology Agency/CREST, Kawaguchi, Saitama 332-0012, Japan, and
| | - Yo Shinoda
- From the Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
- Japan Science and Technology Agency/CREST, Kawaguchi, Saitama 332-0012, Japan, and
| | - Yukiko Sekine
- From the Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Chihiro Saruta
- From the Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
| | - Makoto Itakura
- Japan Science and Technology Agency/CREST, Kawaguchi, Saitama 332-0012, Japan, and
- the Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Kanagawa 228-8555, Japan
| | - Masami Takahashi
- Japan Science and Technology Agency/CREST, Kawaguchi, Saitama 332-0012, Japan, and
- the Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Kanagawa 228-8555, Japan
| | - Teiichi Furuichi
- From the Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan
- Japan Science and Technology Agency/CREST, Kawaguchi, Saitama 332-0012, Japan, and
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Sturek JM, Castle JD, Trace AP, Page LC, Castle AM, Evans-Molina C, Parks JS, Mirmira RG, Hedrick CC. An intracellular role for ABCG1-mediated cholesterol transport in the regulated secretory pathway of mouse pancreatic beta cells. J Clin Invest 2010; 120:2575-89. [PMID: 20530872 DOI: 10.1172/jci41280] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 04/14/2010] [Indexed: 01/12/2023] Open
Abstract
Cholesterol is a critical component of cell membranes, and cellular cholesterol levels and distribution are tightly regulated in mammals. Recent evidence has revealed a critical role for pancreatic beta cell-specific cholesterol homeostasis in insulin secretion as well as in beta cell dysfunction in diabetes and the metabolic response to thiazolidinediones (TZDs), which are antidiabetic drugs. The ATP-binding cassette transporter G1 (ABCG1) has been shown to play a role in cholesterol efflux, but its role in beta cells is currently unknown. In other cell types, ABCG1 expression is downregulated in diabetes and upregulated by TZDs. Here we have demonstrated an intracellular role for ABCG1 in beta cells. Loss of ABCG1 expression impaired insulin secretion both in vivo and in vitro, but it had no effect on cellular cholesterol content or efflux. Subcellular localization studies showed the bulk of ABCG1 protein to be present in insulin granules. Loss of ABCG1 led to altered granule morphology and reduced granule cholesterol levels. Administration of exogenous cholesterol restored granule morphology and cholesterol content and rescued insulin secretion in ABCG1-deficient islets. These findings suggest that ABCG1 acts primarily to regulate subcellular cholesterol distribution in mouse beta cells. Furthermore, islet ABCG1 expression was reduced in diabetic mice and restored by TZDs, implicating a role for regulation of islet ABCG1 expression in diabetes pathogenesis and treatment.
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Affiliation(s)
- Jeffrey M Sturek
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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Wuttke A, Sågetorp J, Tengholm A. Distinct plasma-membrane PtdIns(4)P and PtdIns(4,5)P2 dynamics in secretagogue-stimulated beta-cells. J Cell Sci 2010; 123:1492-502. [PMID: 20375060 DOI: 10.1242/jcs.060525] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphoinositides regulate numerous processes in various subcellular compartments. Whereas many stimuli trigger changes in the plasma-membrane PtdIns(4,5)P(2) concentration, little is known about its precursor, PtdIns(4)P, in particular whether there are stimulus-induced alterations independent of those of PtdIns(4,5)P(2). We investigated plasma-membrane PtdIns(4)P and PtdIns(4,5)P(2) dynamics in insulin-secreting MIN6 cells using fluorescent translocation biosensors and total internal reflection microscopy. Loss of PtdIns(4,5)P(2) induced by phospholipase C (PLC)-activating receptor agonists or stimulatory glucose concentrations was paralleled by increased PtdIns(4)P levels. In addition, glucose-stimulated cells regularly showed anti-synchronous oscillations of the two lipids. Whereas glucose-induced PtdIns(4)P elevation required voltage-gated Ca(2+) entry and was mimicked by membrane-depolarizing stimuli, the receptor-induced response was Ca(2+) independent, but sensitive to protein kinase C (PKC) inhibition and mimicked by phorbol ester stimulation. We conclude that glucose and PLC-activating receptor stimuli trigger Ca(2+)- and PKC-dependent changes in the plasma-membrane PtdIns(4)P concentration that are independent of the effects on PtdIns(4,5)P(2). These findings indicate that enhanced formation of PtdIns(4)P, apart from ensuring efficient replenishment of the PtdIns(4,5)P(2) pool, might serve an independent signalling function by regulating the association of PtdIns(4)P-binding proteins with the plasma membrane.
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Affiliation(s)
- Anne Wuttke
- Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, SE-751 23 Uppsala, Sweden
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Kasai H, Hatakeyama H, Ohno M, Takahashi N. Exocytosis in islet beta-cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:305-38. [PMID: 20217504 DOI: 10.1007/978-90-481-3271-3_14] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The development of technologies that allow for live optical imaging of exocytosis from beta-cells has greatly improved our understanding of insulin secretion. Two-photon imaging, in particular, has enabled researchers to visualize the exocytosis of large dense-core vesicles (LDCVs) containing insulin from beta-cells in intact islets of Langerhans. These studies have revealed that high glucose levels induce two phases of insulin secretion and that this release is dependent upon cytosolic Ca(2+) and cAMP. This technology has also made it possible to examine the spatial profile of insulin exocytosis in these tissues and compare that profile with those of other secretory glands. Such studies have led to the discovery of the massive exocytosis of synaptic-like microvesicles (SLMVs) in beta-cells. These imaging studies have also helped clarify facets of insulin exocytosis that cannot be properly addressed using the currently available electrophysiological techniques. This chapter provides a concise introduction to the field of optical imaging for those researchers who wish to characterize exocytosis from beta-cells in the islets of Langerhans.
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Affiliation(s)
- Haruo Kasai
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, The University of Tokyo, Hongo, Tokyo 113-0033, Japan.
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