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Loh YP, Xiao L, Park JJ. Trafficking of hormones and trophic factors to secretory and extracellular vesicles: a historical perspective and new hypothesis. EXTRACELLULAR VESICLES AND CIRCULATING NUCLEIC ACIDS 2023; 4:568-587. [PMID: 38435713 PMCID: PMC10906782 DOI: 10.20517/evcna.2023.34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 03/05/2024]
Abstract
It is well known that peptide hormones and neurotrophic factors are intercellular messengers that are packaged into secretory vesicles in endocrine cells and neurons and released by exocytosis upon the stimulation of the cells in a calcium-dependent manner. These secreted molecules bind to membrane receptors, which then activate signal transduction pathways to mediate various endocrine/trophic functions. Recently, there is evidence that these molecules are also in extracellular vesicles, including small extracellular vesicles (sEVs), which appear to be taken up by recipient cells. This finding raised the hypothesis that they may have functions differentiated from their classical secretory hormone/neurotrophic factor actions. In this article, the historical perspective and updated mechanisms for the sorting and packaging of hormones and neurotrophic factors into secretory vesicles and their transport in these organelles for release at the plasma membrane are reviewed. In contrast, little is known about the packaging of hormones and neurotrophic factors into extracellular vesicles. One proposal is that these molecules could be sorted at the trans-Golgi network, which then buds to form Golgi-derived vesicles that can fuse to endosomes and subsequently form intraluminal vesicles. They are then taken up by multivesicular bodies to form extracellular vesicles, which are subsequently released. Other possible mechanisms for packaging RSP proteins into sEVs are discussed. We highlight some studies in the literature that suggest the dual vesicular pathways for the release of hormones and neurotrophic factors from the cell may have some physiological significance in intercellular communication.
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Affiliation(s)
- Y. Peng Loh
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lan Xiao
- Section on Cellular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joshua J. Park
- Scientific Review Branch, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
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Cheng XW, Narisawa M, Wang H, Piao L. Overview of multifunctional cysteinyl cathepsins in atherosclerosis-based cardiovascular disease: from insights into molecular functions to clinical implications. Cell Biosci 2023; 13:91. [PMID: 37202785 DOI: 10.1186/s13578-023-01040-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Accepted: 05/01/2023] [Indexed: 05/20/2023] Open
Abstract
Cysteinyl cathepsins (CTSs) are widely known to have a proteolysis function that mediates recycling of unwanted proteins in endosomes and lysosomes, and investigation of CTSs has greatly improved with advances in live-imaging techniques both in vivo and in vitro, leading to three key findings. (1) CTSs are relocated from the lysosomes to other cellular spaces (i.e., cytosol, nucleus, nuclear membrane, plasma membrane, and extracellular milieu). (2) In addition to acidic cellular compartments, CTSs also exert biological activity in neutral environments. (3) CTSs also exert multiple nontraditional functions in, for example, extracellular matrix metabolism, cell signaling transduction, protein processing/trafficking, and cellular events. Various stimuli regulate the expression and activities of CTSs in vivo and vitro-e.g., inflammatory cytokines, oxidative stress, neurohormones, and growth factors. Accumulating evidence has confirmed the participation of CTSs in vascular diseases characterized by atherosclerosis, plaque rupture, thrombosis, calcification, aneurysm, restenosis/in-stent-restenosis, and neovasel formation. Circulating and tissue CTSs are promising as biomarkers and as a diagnostic imaging tool in patients with atherosclerosis-based cardiovascular disease (ACVD), and pharmacological interventions with their specific and non-specific inhibitors, and cardiovascular drugs might have potential for the therapeutic targeting of CTSs in animals. This review focuses on the update findings on CTS biology and the involvement of CTSs in the initiation and progression of ACVD and discusses the potential use of CTSs as biomarkers and small-molecule targets to prevent deleterious nontraditional functions in ACVD.
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Affiliation(s)
- Xian Wu Cheng
- Department of Cardiology and Hypertension, Yanbian University Hospital, 1327 Juzijie, Yanjin, Jilin, 133000, People's Republic of China.
- Jilin Provincial Key Laboratory of Stress and Cardiovascular Disease, Yanbian University Hospital, Yanjin, 133000, Jilin, People's Republic of China.
- Department of Cardiology and Hypertension, Jilin Provincial Key Laboratory of Stress and Cardiovascular Disease, Yanbian University Hospital, 1327 Juzijie, Yanji, Jilin PR. 133000, China.
| | - Megumi Narisawa
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Aichiken, 4668550, Japan
| | - Hailong Wang
- Department of Cardiology and Hypertension, Yanbian University Hospital, 1327 Juzijie, Yanjin, Jilin, 133000, People's Republic of China
- Jilin Provincial Key Laboratory of Stress and Cardiovascular Disease, Yanbian University Hospital, Yanjin, 133000, Jilin, People's Republic of China
| | - Limei Piao
- Department of Cardiology and Hypertension, Yanbian University Hospital, 1327 Juzijie, Yanjin, Jilin, 133000, People's Republic of China
- Jilin Provincial Key Laboratory of Stress and Cardiovascular Disease, Yanbian University Hospital, Yanjin, 133000, Jilin, People's Republic of China
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Hook G, Reinheckel T, Ni J, Wu Z, Kindy M, Peters C, Hook V. Cathepsin B Gene Knockout Improves Behavioral Deficits and Reduces Pathology in Models of Neurologic Disorders. Pharmacol Rev 2022; 74:600-629. [PMID: 35710131 PMCID: PMC9553114 DOI: 10.1124/pharmrev.121.000527] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cathepsin B (CTSB) is a powerful lysosomal protease. This review evaluated CTSB gene knockout (KO) outcomes for amelioration of brain dysfunctions in neurologic diseases and aging animal models. Deletion of the CTSB gene resulted in significant improvements in behavioral deficits, neuropathology, and/or biomarkers in traumatic brain injury, ischemia, inflammatory pain, opiate tolerance, epilepsy, aging, transgenic Alzheimer's disease (AD), and periodontitis AD models as shown in 12 studies. One study found beneficial effects for double CTSB and cathepsin S KO mice in a multiple sclerosis model. Transgenic AD models using amyloid precursor protein (APP) mimicking common sporadic AD in three studies showed that CTSB KO improved memory, neuropathology, and biomarkers; two studies used APP representing rare familial AD and found no CTSB KO effect, and two studies used highly engineered APP constructs and reported slight increases in a biomarker. In clinical studies, all reports found that CTSB enzyme was upregulated in diverse neurologic disorders, including AD in which elevated CTSB was positively correlated with cognitive dysfunction. In a wide range of neurologic animal models, CTSB was also upregulated and not downregulated. Further, human genetic mutation data provided precedence for CTSB upregulation causing disease. Thus, the consilience of data is that CTSB gene KO results in improved brain dysfunction and reduced pathology through blockade of CTSB enzyme upregulation that causes human neurologic disease phenotypes. The overall findings provide strong support for CTSB as a rational drug target and for CTSB inhibitors as therapeutic candidates for a wide range of neurologic disorders. SIGNIFICANCE STATEMENT: This review provides a comprehensive compilation of the extensive data on the effects of deleting the cathepsin B (CTSB) gene in neurological and aging mouse models of brain disorders. Mice lacking the CTSB gene display improved neurobehavioral deficits, reduced neuropathology, and amelioration of neuronal cell death and inflammatory biomarkers. The significance of the compelling CTSB evidence is that the data consilience validates CTSB as a drug target for discovery of CTSB inhibitors as potential therapeutics for treating numerous neurological diseases.
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Affiliation(s)
- Gregory Hook
- American Life Science Pharmaceuticals, La Jolla, California (G.H.); Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany (T.R.); German Cancer Consortium (DKTK) Partner Site Freiburg, Freiburg, Germany (T.R.); German Cancer Research Center (DKFZ), Heidelberg, Germany (T.R); Center for Biological Signaling Studies BIOSS, Albert Ludwigs University, Freiburg, Germany (T.R.); Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China (J.N.); Department of Aging Science and Pharmacology, OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan (Z.W); Taneja College of Pharmacy, Department of Pharmaceutical Sciences, University of South Florida, Tampa, Florida (M.K.); James A Haley VAMC, Research Service, Tampa, Florida (M.K.); Institute of Molecular Medicine and Cell Research, Faculty of Biology, Albert Ludwigs University, Freiburg, Germany (C.P.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, CA (V.H.); and Department of Neuroscience and Department of Pharmacology, School of Medicine, University of California, La Jolla, CA (V.H.)
| | - Thomas Reinheckel
- American Life Science Pharmaceuticals, La Jolla, California (G.H.); Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany (T.R.); German Cancer Consortium (DKTK) Partner Site Freiburg, Freiburg, Germany (T.R.); German Cancer Research Center (DKFZ), Heidelberg, Germany (T.R); Center for Biological Signaling Studies BIOSS, Albert Ludwigs University, Freiburg, Germany (T.R.); Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China (J.N.); Department of Aging Science and Pharmacology, OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan (Z.W); Taneja College of Pharmacy, Department of Pharmaceutical Sciences, University of South Florida, Tampa, Florida (M.K.); James A Haley VAMC, Research Service, Tampa, Florida (M.K.); Institute of Molecular Medicine and Cell Research, Faculty of Biology, Albert Ludwigs University, Freiburg, Germany (C.P.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, CA (V.H.); and Department of Neuroscience and Department of Pharmacology, School of Medicine, University of California, La Jolla, CA (V.H.)
| | - Junjun Ni
- American Life Science Pharmaceuticals, La Jolla, California (G.H.); Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany (T.R.); German Cancer Consortium (DKTK) Partner Site Freiburg, Freiburg, Germany (T.R.); German Cancer Research Center (DKFZ), Heidelberg, Germany (T.R); Center for Biological Signaling Studies BIOSS, Albert Ludwigs University, Freiburg, Germany (T.R.); Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China (J.N.); Department of Aging Science and Pharmacology, OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan (Z.W); Taneja College of Pharmacy, Department of Pharmaceutical Sciences, University of South Florida, Tampa, Florida (M.K.); James A Haley VAMC, Research Service, Tampa, Florida (M.K.); Institute of Molecular Medicine and Cell Research, Faculty of Biology, Albert Ludwigs University, Freiburg, Germany (C.P.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, CA (V.H.); and Department of Neuroscience and Department of Pharmacology, School of Medicine, University of California, La Jolla, CA (V.H.)
| | - Zhou Wu
- American Life Science Pharmaceuticals, La Jolla, California (G.H.); Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany (T.R.); German Cancer Consortium (DKTK) Partner Site Freiburg, Freiburg, Germany (T.R.); German Cancer Research Center (DKFZ), Heidelberg, Germany (T.R); Center for Biological Signaling Studies BIOSS, Albert Ludwigs University, Freiburg, Germany (T.R.); Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China (J.N.); Department of Aging Science and Pharmacology, OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan (Z.W); Taneja College of Pharmacy, Department of Pharmaceutical Sciences, University of South Florida, Tampa, Florida (M.K.); James A Haley VAMC, Research Service, Tampa, Florida (M.K.); Institute of Molecular Medicine and Cell Research, Faculty of Biology, Albert Ludwigs University, Freiburg, Germany (C.P.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, CA (V.H.); and Department of Neuroscience and Department of Pharmacology, School of Medicine, University of California, La Jolla, CA (V.H.)
| | - Mark Kindy
- American Life Science Pharmaceuticals, La Jolla, California (G.H.); Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany (T.R.); German Cancer Consortium (DKTK) Partner Site Freiburg, Freiburg, Germany (T.R.); German Cancer Research Center (DKFZ), Heidelberg, Germany (T.R); Center for Biological Signaling Studies BIOSS, Albert Ludwigs University, Freiburg, Germany (T.R.); Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China (J.N.); Department of Aging Science and Pharmacology, OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan (Z.W); Taneja College of Pharmacy, Department of Pharmaceutical Sciences, University of South Florida, Tampa, Florida (M.K.); James A Haley VAMC, Research Service, Tampa, Florida (M.K.); Institute of Molecular Medicine and Cell Research, Faculty of Biology, Albert Ludwigs University, Freiburg, Germany (C.P.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, CA (V.H.); and Department of Neuroscience and Department of Pharmacology, School of Medicine, University of California, La Jolla, CA (V.H.)
| | - Christoph Peters
- American Life Science Pharmaceuticals, La Jolla, California (G.H.); Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany (T.R.); German Cancer Consortium (DKTK) Partner Site Freiburg, Freiburg, Germany (T.R.); German Cancer Research Center (DKFZ), Heidelberg, Germany (T.R); Center for Biological Signaling Studies BIOSS, Albert Ludwigs University, Freiburg, Germany (T.R.); Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China (J.N.); Department of Aging Science and Pharmacology, OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan (Z.W); Taneja College of Pharmacy, Department of Pharmaceutical Sciences, University of South Florida, Tampa, Florida (M.K.); James A Haley VAMC, Research Service, Tampa, Florida (M.K.); Institute of Molecular Medicine and Cell Research, Faculty of Biology, Albert Ludwigs University, Freiburg, Germany (C.P.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, CA (V.H.); and Department of Neuroscience and Department of Pharmacology, School of Medicine, University of California, La Jolla, CA (V.H.)
| | - Vivian Hook
- American Life Science Pharmaceuticals, La Jolla, California (G.H.); Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert Ludwigs University, Freiburg, Germany (T.R.); German Cancer Consortium (DKTK) Partner Site Freiburg, Freiburg, Germany (T.R.); German Cancer Research Center (DKFZ), Heidelberg, Germany (T.R); Center for Biological Signaling Studies BIOSS, Albert Ludwigs University, Freiburg, Germany (T.R.); Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China (J.N.); Department of Aging Science and Pharmacology, OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan (Z.W); Taneja College of Pharmacy, Department of Pharmaceutical Sciences, University of South Florida, Tampa, Florida (M.K.); James A Haley VAMC, Research Service, Tampa, Florida (M.K.); Institute of Molecular Medicine and Cell Research, Faculty of Biology, Albert Ludwigs University, Freiburg, Germany (C.P.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, CA (V.H.); and Department of Neuroscience and Department of Pharmacology, School of Medicine, University of California, La Jolla, CA (V.H.)
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4
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Xu H, Chang F, Jain S, Heller BA, Han X, Liu Y, Edwards RH. SNX5 targets a monoamine transporter to the TGN for assembly into dense core vesicles by AP-3. J Cell Biol 2022; 221:e202106083. [PMID: 35426896 PMCID: PMC9016777 DOI: 10.1083/jcb.202106083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 12/06/2021] [Accepted: 02/16/2022] [Indexed: 11/22/2022] Open
Abstract
The time course of signaling by peptide hormones, neural peptides, and other neuromodulators depends on their storage inside dense core vesicles (DCVs). Adaptor protein 3 (AP-3) assembles the membrane proteins that confer regulated release of DCVs and is thought to promote their trafficking from endosomes directly to maturing DCVs. We now find that regulated monoamine release from DCVs requires sorting nexin 5 (SNX5). Loss of SNX5 disrupts trafficking of the vesicular monoamine transporter (VMAT) to DCVs. The mechanism involves a role for SNX5 in retrograde transport of VMAT from endosomes to the TGN. However, this role for SNX5 conflicts with the proposed function of AP-3 in trafficking from endosomes directly to DCVs. We now identify a transient role for AP-3 at the TGN, where it associates with DCV cargo. Thus, retrograde transport from endosomes by SNX5 enables DCV assembly at the TGN by AP-3, resolving the apparent antagonism. A novel role for AP-3 at the TGN has implications for other organelles that also depend on this adaptor.
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Affiliation(s)
- Hongfei Xu
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Fei Chang
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Shweta Jain
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
| | - Bradley Austin Heller
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
| | - Xu Han
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Yongjian Liu
- Jiangsu Key Laboratory of Xenotransplantation, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
- Departments of Pharmacology and Biological Chemistry, University of Pittsburgh, Pittsburgh, PA
| | - Robert H. Edwards
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA
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5
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Andersen RC, Schmidt JH, Rombach J, Lycas MD, Christensen NR, Lund VK, Stapleton DS, Pedersen SS, Olsen MA, Stoklund M, Noes-Holt G, Nielsen TT, Keller MP, Jansen AM, Herlo R, Pietropaolo M, Simonsen JB, Kjærulff O, Holst B, Attie AD, Gether U, Madsen KL. Coding variants identified in diabetic patients alter PICK1 BAR domain function in insulin granule biogenesis. J Clin Invest 2022; 132:144904. [PMID: 35077398 PMCID: PMC8884907 DOI: 10.1172/jci144904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 01/14/2022] [Indexed: 11/17/2022] Open
Abstract
Bin/amphiphysin/Rvs (BAR) domains are positively charged crescent-shaped modules that mediate curvature of negatively charged lipid membranes during remodeling processes. The BAR domain proteins PICK1, ICA69, and the arfaptins have recently been demonstrated to coordinate the budding and formation of immature secretory granules (ISGs) at the trans-Golgi network. Here, we identify 4 coding variants in the PICK1 gene from a whole-exome screening of Danish patients with diabetes that each involve a change in positively charged residues in the PICK1 BAR domain. All 4 coding variants failed to rescue insulin content in INS-1E cells upon knock down of endogenous PICK1. Moreover, 2 variants showed dominant-negative properties. In vitro assays addressing BAR domain function suggested that the coding variants compromised BAR domain function but increased the capacity to cause fission of liposomes. Live confocal microscopy and super-resolution microscopy further revealed that PICK1 resides transiently on ISGs before egress via vesicular budding events. Interestingly, this egress of PICK1 was accelerated in the coding variants. We propose that PICK1 assists in or complements the removal of excess membrane and generic membrane trafficking proteins, and possibly also insulin, from ISGs during the maturation process; and that the coding variants may cause premature budding, possibly explaining their dominant-negative function.
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Affiliation(s)
- Rita C. Andersen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jan H. Schmidt
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Joscha Rombach
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Matthew D. Lycas
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nikolaj R. Christensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Viktor K. Lund
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Donnie S. Stapleton
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Signe S. Pedersen
- Beta Cell Biology Group, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mathias A. Olsen
- Beta Cell Biology Group, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel Stoklund
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gith Noes-Holt
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tommas T.E. Nielsen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mark P. Keller
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Anna M. Jansen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Herlo
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Massimo Pietropaolo
- Diabetes Research Center, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | - Jens B. Simonsen
- Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Ole Kjærulff
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Birgitte Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alan D. Attie
- Department of Biochemistry, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Ulrik Gether
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kenneth L. Madsen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Cho CJ, Park D, Mills JC. ELAPOR1 is a secretory granule maturation-promoting factor that is lost during paligenosis. Am J Physiol Gastrointest Liver Physiol 2022; 322:G49-G65. [PMID: 34816763 PMCID: PMC8698547 DOI: 10.1152/ajpgi.00246.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A single transcription factor, MIST1 (BHLHA15), maximizes secretory function in diverse secretory cells (like pancreatic acinar cells) by transcriptionally upregulating genes that elaborate secretory architecture. Here, we show that the scantly studied MIST1 target, ELAPOR1 (endosome/lysosome-associated apoptosis and autophagy regulator 1), is an evolutionarily conserved, novel mannose-6-phosphate receptor (M6PR) domain-containing protein. ELAPOR1 expression was specific to zymogenic cells (ZCs, the MIST1-expressing population in the stomach). ELAPOR1 expression was lost as tissue injury caused ZCs to undergo paligenosis (i.e., to become metaplastic and reenter the cell cycle). In cultured cells, ELAPOR1 trafficked with cis-Golgi resident proteins and with the trans-Golgi and late endosome protein: cation-independent M6PR. Secretory vesicle trafficking was disrupted by expression of ELAPOR1 truncation mutants. Mass spectrometric analysis of co-immunoprecipitated proteins showed ELAPOR1 and CI-M6PR shared many binding partners. However, CI-M6PR and ELAPOR1 must function differently, as CI-M6PR co-immunoprecipitated more lysosomal proteins and was not decreased during paligenosis in vivo. We generated Elapor1-/- mice to determine ELAPOR1 function in vivo. Consistent with in vitro findings, secretory granule maturation was defective in Elapor1-/- ZCs. Our results identify a role for ELAPOR1 in secretory granule maturation and help clarify how a single transcription factor maintains mature exocrine cell architecture in homeostasis and helps dismantle it during paligenosis.NEW & NOTEWORTHY Here, we find the MIST1 (BHLHA15) transcriptional target ELAPOR1 is an evolutionarily conserved, trans-Golgi/late endosome M6PR domain-containing protein that is specific to gastric zymogenic cells and required for normal secretory granule maturation in human cell lines and in mouse stomach.
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Affiliation(s)
- Charles J. Cho
- 1Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Dongkook Park
- 2Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Jason C. Mills
- 1Department of Medicine, Baylor College of Medicine, Houston, Texas,3Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas,4Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
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7
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Wen G, Pang H, Wu X, Jiang E, Zhang X, Zhan X. Proteomic characterization of secretory granules in dopaminergic neurons indicates chromogranin/secretogranin-mediated protein processing impairment in Parkinson's disease. Aging (Albany NY) 2021; 13:20335-20358. [PMID: 34420933 PMCID: PMC8436928 DOI: 10.18632/aging.203415] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 08/03/2021] [Indexed: 11/25/2022]
Abstract
Parkinson’s disease (PD) is an aging disorder related to vesicle transport dysfunctions and neurotransmitter secretion. Secretory granules (SGs) are large dense-core vesicles for the biosynthesis of neuropeptides and hormones. At present, the involvement of SGs impairment in PD remains unclear. In the current study, we found that the number of SGs in tyrosine hydroxylase-positive neurons and the marker proteins secretogranin III (Scg3) significantly decreased in the substantia nigra and striatum regions of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) exposed mice. Proteomic study of SGs purified from the dopaminergic SH-sy5Y cells under 1-methyl-4-phenylpyridinium (MPP+) treatments (ProteomeXchange PXD023937) identified 536 significantly differentially expressed proteins. The result indicated that disabled lysosome and peroxisome, lipid and energy metabolism disorders are three characteristic features. Protein-protein interaction analysis of 56 secretory proteins and 140 secreted proteins suggested that the peptide processing mediated by chromogranin/secretogranin in SGs was remarkably compromised, accompanied by decreased candidate proteins and peptides neurosecretory protein (VGF), neuropeptide Y, apolipoprotein E, and an increased level of proenkephalin. The current study provided an extensive proteinogram of SGs in PD. It is helpful to understand the molecular mechanisms in the disease.
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Affiliation(s)
- Gehua Wen
- School of Forensic Medicine, China Medical University, Shenyang, PR China
| | - Hao Pang
- School of Forensic Medicine, China Medical University, Shenyang, PR China
| | - Xu Wu
- School of Forensic Medicine, China Medical University, Shenyang, PR China
| | - Enzhu Jiang
- School of Forensic Medicine, China Medical University, Shenyang, PR China
| | - Xique Zhang
- Department of Geriatrics, The First Affiliated Hospital of China Medical University, Shenyang, PR China
| | - Xiaoni Zhan
- School of Forensic Medicine, China Medical University, Shenyang, PR China
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8
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Germanos M, Gao A, Taper M, Yau B, Kebede MA. Inside the Insulin Secretory Granule. Metabolites 2021; 11:metabo11080515. [PMID: 34436456 PMCID: PMC8401130 DOI: 10.3390/metabo11080515] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 12/19/2022] Open
Abstract
The pancreatic β-cell is purpose-built for the production and secretion of insulin, the only hormone that can remove glucose from the bloodstream. Insulin is kept inside miniature membrane-bound storage compartments known as secretory granules (SGs), and these specialized organelles can readily fuse with the plasma membrane upon cellular stimulation to release insulin. Insulin is synthesized in the endoplasmic reticulum (ER) as a biologically inactive precursor, proinsulin, along with several other proteins that will also become members of the insulin SG. Their coordinated synthesis enables synchronized transit through the ER and Golgi apparatus for congregation at the trans-Golgi network, the initiating site of SG biogenesis. Here, proinsulin and its constituents enter the SG where conditions are optimized for proinsulin processing into insulin and subsequent insulin storage. A healthy β-cell is continually generating SGs to supply insulin in vast excess to what is secreted. Conversely, in type 2 diabetes (T2D), the inability of failing β-cells to secrete may be due to the limited biosynthesis of new insulin. Factors that drive the formation and maturation of SGs and thus the production of insulin are therefore critical for systemic glucose control. Here, we detail the formative hours of the insulin SG from the luminal perspective. We do this by mapping the journey of individual members of the SG as they contribute to its genesis.
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Isolation and Proteomics of the Insulin Secretory Granule. Metabolites 2021; 11:metabo11050288. [PMID: 33946444 PMCID: PMC8147143 DOI: 10.3390/metabo11050288] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 12/21/2022] Open
Abstract
Insulin, a vital hormone for glucose homeostasis is produced by pancreatic beta-cells and when secreted, stimulates the uptake and storage of glucose from the blood. In the pancreas, insulin is stored in vesicles termed insulin secretory granules (ISGs). In Type 2 diabetes (T2D), defects in insulin action results in peripheral insulin resistance and beta-cell compensation, ultimately leading to dysfunctional ISG production and secretion. ISGs are functionally dynamic and many proteins present either on the membrane or in the lumen of the ISG may modulate and affect different stages of ISG trafficking and secretion. Previously, studies have identified few ISG proteins and more recently, proteomics analyses of purified ISGs have uncovered potential novel ISG proteins. This review summarizes the proteins identified in the current ISG proteomes from rat insulinoma INS-1 and INS-1E cell lines. Here, we also discuss techniques of ISG isolation and purification, its challenges and potential future directions.
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10
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The SARS-CoV-2 and other human coronavirus spike proteins are fine-tuned towards temperature and proteases of the human airways. PLoS Pathog 2021; 17:e1009500. [PMID: 33886690 PMCID: PMC8061995 DOI: 10.1371/journal.ppat.1009500] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/24/2021] [Indexed: 12/13/2022] Open
Abstract
The high transmissibility of SARS-CoV-2 is related to abundant replication in the upper airways, which is not observed for the other highly pathogenic coronaviruses SARS-CoV and MERS-CoV. We here reveal features of the coronavirus spike (S) protein, which optimize the virus towards the human respiratory tract. First, the S proteins exhibit an intrinsic temperature preference, corresponding with the temperature of the upper or lower airways. Pseudoviruses bearing the SARS-CoV-2 spike (SARS-2-S) were more infectious when produced at 33°C instead of 37°C, a property shared with the S protein of HCoV-229E, a common cold coronavirus. In contrast, the S proteins of SARS-CoV and MERS-CoV favored 37°C, in accordance with virus preference for the lower airways. Next, SARS-2-S-driven entry was efficiently activated by not only TMPRSS2, but also the TMPRSS13 protease, thus broadening the cell tropism of SARS-CoV-2. Both proteases proved relevant in the context of authentic virus replication. TMPRSS13 appeared an effective spike activator for the virulent coronaviruses but not the low pathogenic HCoV-229E virus. Activation of SARS-2-S by these surface proteases requires processing of the S1/S2 cleavage loop, in which both the furin recognition motif and extended loop length proved critical. Conversely, entry of loop deletion mutants is significantly increased in cathepsin-rich cells. Finally, we demonstrate that the D614G mutation increases SARS-CoV-2 stability, particularly at 37°C, and, enhances its use of the cathepsin L pathway. This indicates a link between S protein stability and usage of this alternative route for virus entry. Since these spike properties may promote virus spread, they potentially explain why the spike-G614 variant has replaced the early D614 variant to become globally predominant. Collectively, our findings reveal adaptive mechanisms whereby the coronavirus spike protein is adjusted to match the temperature and protease conditions of the airways, to enhance virus transmission and pathology. The devastating COVID-19 pandemic is caused by SARS-CoV-2, a novel virus that despite recent zoonotic introduction is already very well adapted to its human host. Its rapid spread is related to abundant replication in the upper airways, which is not observed for other highly pathogenic human coronaviruses. To understand the role of the viral spike protein in this airway adaptation, we constructed pseudoviruses of SARS-CoV-2 and other coronaviruses that cause severe pneumonia or, on the contrary, a mild common cold. The key findings were verified with authentic virus. We reveal features of the spike proteins, which optimize the coronavirus towards specific parts of the respiratory tract. Namely, we show that the spike proteins exhibit intrinsic temperature preference to precisely match the upper (~33°C) or lower (37°C) airways. We recognized which proteases of human airways activate the spike for virus entry, in particular one protease that may mediate coronavirus virulence. Finally, a link was perceived between spike stability and entry via endosomal proteases. We propose that these mechanisms of spike fine-tuning may have contributed to a global shift in SARS-CoV-2 epidemiology, from the early spike-D614 to the currently predominating G614 variant.
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11
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Ma CIJ, Burgess J, Brill JA. Maturing secretory granules: Where secretory and endocytic pathways converge. Adv Biol Regul 2021; 80:100807. [PMID: 33866198 DOI: 10.1016/j.jbior.2021.100807] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 10/21/2022]
Abstract
Secretory granules (SGs) are specialized organelles responsible for the storage and regulated release of various biologically active molecules from the endocrine and exocrine systems. Thus, proper SG biogenesis is critical to normal animal physiology. Biogenesis of SGs starts at the trans-Golgi network (TGN), where immature SGs (iSGs) bud off and undergo maturation before fusing with the plasma membrane (PM). How iSGs mature is unclear, but emerging studies have suggested an important role for the endocytic pathway. The requirement for endocytic machinery in SG maturation blurs the line between SGs and another class of secretory organelles called lysosome-related organelles (LROs). Therefore, it is important to re-evaluate the differences and similarities between SGs and LROs.
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Affiliation(s)
- Cheng-I Jonathan Ma
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Medical Sciences Building, Room 2374, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Jason Burgess
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, Medical Sciences Building, Room 4396, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Julie A Brill
- Cell Biology Program, The Hospital for Sick Children, PGCRL Building, Room 15.9716, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada; Institute of Medical Science, University of Toronto, Medical Sciences Building, Room 2374, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada; Department of Molecular Genetics, University of Toronto, Medical Sciences Building, Room 4396, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
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12
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Burns CH, Yau B, Rodriguez A, Triplett J, Maslar D, An YS, van der Welle REN, Kossina RG, Fisher MR, Strout GW, Bayguinov PO, Veenendaal T, Chitayat D, Fitzpatrick JAJ, Klumperman J, Kebede MA, Asensio CS. Pancreatic β-Cell-Specific Deletion of VPS41 Causes Diabetes Due to Defects in Insulin Secretion. Diabetes 2021; 70:436-448. [PMID: 33168621 PMCID: PMC7881869 DOI: 10.2337/db20-0454] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 11/03/2020] [Indexed: 12/14/2022]
Abstract
Insulin secretory granules (SGs) mediate the regulated secretion of insulin, which is essential for glucose homeostasis. The basic machinery responsible for this regulated exocytosis consists of specific proteins present both at the plasma membrane and on insulin SGs. The protein composition of insulin SGs thus dictates their release properties, yet the mechanisms controlling insulin SG formation, which determine this molecular composition, remain poorly understood. VPS41, a component of the endolysosomal tethering homotypic fusion and vacuole protein sorting (HOPS) complex, was recently identified as a cytosolic factor involved in the formation of neuroendocrine and neuronal granules. We now find that VPS41 is required for insulin SG biogenesis and regulated insulin secretion. Loss of VPS41 in pancreatic β-cells leads to a reduction in insulin SG number, changes in their transmembrane protein composition, and defects in granule-regulated exocytosis. Exploring a human point mutation, identified in patients with neurological but no endocrine defects, we show that the effect on SG formation is independent of HOPS complex formation. Finally, we report that mice with a deletion of VPS41 specifically in β-cells develop diabetes due to severe depletion of insulin SG content and a defect in insulin secretion. In sum, our data demonstrate that VPS41 contributes to glucose homeostasis and metabolism.
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Affiliation(s)
| | - Belinda Yau
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia
| | | | - Jenna Triplett
- Department of Biological Sciences, University of Denver, Denver, CO
| | - Drew Maslar
- Department of Biological Sciences, University of Denver, Denver, CO
| | - You Sun An
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia
| | - Reini E N van der Welle
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Ross G Kossina
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
| | - Max R Fisher
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
| | - Gregory W Strout
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
| | - Peter O Bayguinov
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
| | - Tineke Veenendaal
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - David Chitayat
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynaecology, University of Toronto, Toronto, Ontario, Canada
| | - James A J Fitzpatrick
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO
- Departments of Neuroscience and Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO
| | - Judith Klumperman
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Melkam A Kebede
- Discipline of Physiology, School of Medical Sciences, Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia
| | - Cedric S Asensio
- Department of Biological Sciences, University of Denver, Denver, CO
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13
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Carrat GR, Haythorne E, Tomas A, Haataja L, Müller A, Arvan P, Piunti A, Cheng K, Huang M, Pullen TJ, Georgiadou E, Stylianides T, Amirruddin NS, Salem V, Distaso W, Cakebread A, Heesom KJ, Lewis PA, Hodson DJ, Briant LJ, Fung AC, Sessions RB, Alpy F, Kong AP, Benke PI, Torta F, Teo AKK, Leclerc I, Solimena M, Wigley DB, Rutter GA. The type 2 diabetes gene product STARD10 is a phosphoinositide-binding protein that controls insulin secretory granule biogenesis. Mol Metab 2020; 40:101015. [PMID: 32416313 PMCID: PMC7322359 DOI: 10.1016/j.molmet.2020.101015] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/24/2020] [Accepted: 05/05/2020] [Indexed: 02/09/2023] Open
Abstract
OBJECTIVE Risk alleles for type 2 diabetes at the STARD10 locus are associated with lowered STARD10 expression in the β-cell, impaired glucose-induced insulin secretion, and decreased circulating proinsulin:insulin ratios. Although likely to serve as a mediator of intracellular lipid transfer, the identity of the transported lipids and thus the pathways through which STARD10 regulates β-cell function are not understood. The aim of this study was to identify the lipids transported and affected by STARD10 in the β-cell and the role of the protein in controlling proinsulin processing and insulin granule biogenesis and maturation. METHODS We used isolated islets from mice deleted selectively in the β-cell for Stard10 (βStard10KO) and performed electron microscopy, pulse-chase, RNA sequencing, and lipidomic analyses. Proteomic analysis of STARD10 binding partners was executed in the INS1 (832/13) cell line. X-ray crystallography followed by molecular docking and lipid overlay assay was performed on purified STARD10 protein. RESULTS βStard10KO islets had a sharply altered dense core granule appearance, with a dramatic increase in the number of "rod-like" dense cores. Correspondingly, basal secretion of proinsulin was increased versus wild-type islets. The solution of the crystal structure of STARD10 to 2.3 Å resolution revealed a binding pocket capable of accommodating polyphosphoinositides, and STARD10 was shown to bind to inositides phosphorylated at the 3' position. Lipidomic analysis of βStard10KO islets demonstrated changes in phosphatidylinositol levels, and the inositol lipid kinase PIP4K2C was identified as a STARD10 binding partner. Also consistent with roles for STARD10 in phosphoinositide signalling, the phosphoinositide-binding proteins Pirt and Synaptotagmin 1 were amongst the differentially expressed genes in βStard10KO islets. CONCLUSION Our data indicate that STARD10 binds to, and may transport, phosphatidylinositides, influencing membrane lipid composition, insulin granule biosynthesis, and insulin processing.
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Affiliation(s)
- Gaelle R. Carrat
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK
| | - Elizabeth Haythorne
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK
| | - Alejandra Tomas
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK
| | - Leena Haataja
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Andreas Müller
- Molecular Diabetology, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany,Paul Langerhans Institute Dresden (PLID) of the Helmholtz Center Munich, University Hospital Carl Gustav Carus and Faculty of Medicine of the TU Dresden, Dresden, Germany,German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany,Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Alexandra Piunti
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK,Lille 1 University-Science and Technology, Cité Scientifique, 59655, Villeneuve d'Ascq Cedex, France
| | - Kaiying Cheng
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
| | - Mutian Huang
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK
| | - Timothy J. Pullen
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK,Department of Diabetes, Faculty of Life Science and Medicine, King's College London, London, UK
| | - Eleni Georgiadou
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK
| | - Theodoros Stylianides
- Loughborough University, Centre of Innovative and Collaborative Construction Engineering, Leicestershire, LE11 3TU, UK
| | - Nur Shabrina Amirruddin
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), A∗STAR, Proteos, Singapore, 138673, Singapore,Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119228, Singapore
| | - Victoria Salem
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK,Section of Investigative Medicine, Department of Medicine, Imperial College London, du Cane Road, London, W12 0NN, UK
| | - Walter Distaso
- Imperial College Business School, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Andrew Cakebread
- London Metallomics Facility, King's College London, Strand, London, WC2R 2LS, UK
| | | | | | - David J. Hodson
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK,Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, UK,Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, Midlands, UK
| | - Linford J. Briant
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Annie C.H. Fung
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Richard B. Sessions
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, BS8 1TD, UK
| | - Fabien Alpy
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM) U1258, Centre National de la Recherche Scientifique (CNRS), UMR 7104, Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Alice P.S. Kong
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Peter I. Benke
- Singapore Lipidomics Incubator, Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Mdical Drive, Singapore, 117596, Singapore
| | - Federico Torta
- Singapore Lipidomics Incubator, Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Mdical Drive, Singapore, 117596, Singapore
| | - Adrian Kee Keong Teo
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), A∗STAR, Proteos, Singapore, 138673, Singapore,Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119228, Singapore,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117596, Singapore
| | - Isabelle Leclerc
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK
| | - Michele Solimena
- Molecular Diabetology, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany,Paul Langerhans Institute Dresden (PLID) of the Helmholtz Center Munich, University Hospital Carl Gustav Carus and Faculty of Medicine of the TU Dresden, Dresden, Germany,German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany,Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
| | - Dale B. Wigley
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
| | - Guy A. Rutter
- Section of Cell Biology and Functional Genomics, Imperial College London, du Cane Road, London, W12 0NN, UK,Corresponding author. +44 (0)20 7594 3340.
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Luziga C. Immunoreactivity of cytotoxic T-lymphocyte antigen 2 alpha in mouse pancreatic islet cells. Anat Histol Embryol 2020; 49:382-389. [PMID: 32059262 DOI: 10.1111/ahe.12541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 12/26/2019] [Accepted: 01/29/2020] [Indexed: 11/29/2022]
Abstract
Cells of the pancreatic islets produce several molecules including insulin (beta cells), glucagon (alpha cells), somatostatin (delta cells), pancreatic polypeptide (PP cells), ghrelin (epsilon cells), serotonin (enterochromaffin cells), gastrin (G cells) and small granules of unknown content secreted by the P/D1 cells. Secretion mechanism of some of these molecules is still poorly understood. However, Cathepsin L is shown to regulate insulin exocytosis in beta cells and activate the trypsinogen produced by the pancreatic serous acini cells into trypsin. The structure of the propeptide region of Cathepsin L is homologous to Cytotoxic T-lymphocyte antigen-2 alpha (CTLA-2 alpha) which is also shown to exhibit selective inhibitory activities against Cathepsin L. It was thought that if CTLA-2 alpha was expressed in the pancreas; then, it would be an important regulator of protease activation and insulin secretion. The purpose of this study was, therefore, to examine by immunohistochemistry the cellular localization and distribution pattern of CTLA-2 alpha in the pancreas. Results showed that strong immunoreactivity was specifically detected in the pancreatic islets (endocrine pancreas) but not in the exocrine pancreas and pancreatic stroma. Immunostaining was further performed to investigate more on localization of Cathepsin L in the pancreas. Strong immunoreactivity for Cathepsin L was detected in the pancreatic islets, serous cells and the pancreas duct system. These findings suggest that CTLA-2 alpha may be involved in the proteolytic processing and secretion of insulin through regulation of Cathepsin L and that the regulated inhibition of Cathepsin L may have therapeutic potential for type 1 diabetes.
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Affiliation(s)
- Claudius Luziga
- Department of Veterinary Anatomy & Pathology, Sokoine University of Agriculture, Morogoro, Tanzania
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15
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Lo CW, Kryvalap Y, Sheu TJ, Chang CH, Czyzyk J. Cellular proliferation in mouse and human pancreatic islets is regulated by serpin B13 inhibition and downstream targeting of E-cadherin by cathepsin L. Diabetologia 2019; 62:822-834. [PMID: 30824970 DOI: 10.1007/s00125-019-4834-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 01/22/2019] [Indexed: 12/11/2022]
Abstract
AIMS/HYPOTHESIS We previously reported that exposure to antibodies neutralising serpin B13, a protease inhibitor expressed in exocrine pancreatic ducts, promotes beta cell proliferation, underscoring the importance of a functional relationship between exocrine and endocrine pancreas. The aim of the present study was to identify the molecular events that link inhibition of serpin B13 to islet cell proliferation. METHODS We used an in vitro culture system consisting of isolated pancreatic islets, an extract of pancreatic ductal epithelium and a monoclonal antibody (mAb) to serpin B13 or IgG isotype control. In vivo studies involved treatment of mice with these mAbs. RESULTS The catalytic activity of cathepsin L (CatL), a cysteine protease target of serpin B13, was augmented in the pancreas of mice injected with serpin B13 mAb. Furthermore, the addition of serpin B13 mAb to the islets, together with the pancreatic ductal epithelium lysate, caused CatL-dependent cleavage of E-cadherin and concomitant upregulation of REG genes, ultimately leading to beta cell proliferation. Direct blockade of E-cadherin with mAb also markedly enhanced REG gene induction, while chemical inhibition of β-catenin, a binding target of E-cadherin, prevented the serpin B13 mAb-induced upregulation of REG genes. CONCLUSIONS/INTERPRETATION Our work implicates the CatL-E-cadherin-REG pathway in the regulation of islet cell proliferation in response to signals generated in exocrine pancreatic tissue and demonstrates that protease activity may promote adaptive changes in the islets. DATA AVAILABILITY Microarray data that support the findings of this study have been deposited in Gene Expression Omnibus (GEO) with the accession no. GSE125151.
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Affiliation(s)
- Chi-Wen Lo
- Department of Pathology and Laboratory Medicine, University of Rochester, Rochester, NY, USA
| | - Yury Kryvalap
- Department of Laboratory Medicine and Pathology, University of Minnesota, 420 Washington Ave SE, Minneapolis, MN, 55455, USA
| | - Tzong-Jen Sheu
- The Center for Musculoskeletal Research, University of Rochester, Rochester, NY, USA
| | - Ching-Ho Chang
- Department of Biology, University of Rochester, Rochester, NY, USA
| | - Jan Czyzyk
- Department of Laboratory Medicine and Pathology, University of Minnesota, 420 Washington Ave SE, Minneapolis, MN, 55455, USA.
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16
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Dufurrena Q, Bäck N, Mains R, Hodgson L, Tanowitz H, Mandela P, Eipper B, Kuliawat R. Kalirin/Trio Rho GDP/GTP exchange factors regulate proinsulin and insulin secretion. J Mol Endocrinol 2018; 62:JME-18-0048.R2. [PMID: 30407917 PMCID: PMC6494717 DOI: 10.1530/jme-18-0048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 11/05/2018] [Indexed: 12/31/2022]
Abstract
Key features for progression to pancreatic β-cell failure and disease are loss of glucose responsiveness and an increased ratio of secreted proinsulin to insulin. Proinsulin and insulin are stored in secretory granules (SGs) and the fine-tuning of hormone output requires signal mediated recruitment of select SG populations according to intracellular location and age. The GTPase Rac1 coordinates multiple signaling pathways that specify SG release and Rac1 activity is controlled in part by GDP/GTP exchange factors (GEFs). To explore the function of two large multidomain GEFs, Kalirin and Trio in β-cells, we manipulated their Rac1-specific GEF1 domain activity by using small molecule inhibitors and by genetically ablating Kalirin. We examined age related secretory granule behavior employing radiolabeling protocols. Loss of Kalirin/Trio function attenuated radioactive proinsulin release by reducing constitutive-like secretion and exocytosis of 2-hour old granules. At later chase times or at steady state, Kalirin/Trio manipulations decreased glucose stimulated insulin output. Finally, use of a Rac1 FRET biosensor with cultured β-cell lines, demonstrated that Kalirin/Trio GEF1 activity was required for normal rearrangement of Rac1 to the plasma membrane in response to glucose. Rac1 activation can be evoked by both glucose metabolism and signaling through the incretin glucagon-like peptide 1 (GLP-1) receptor. GLP-1 addition restored Rac1 localization/activity and insulin secretion in the absence of Kalirin, thereby assigning Kalirin's participation to stimulatory glucose signaling.
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Affiliation(s)
- Quinn Dufurrena
- Department of Medicine, Stony Brook University School of Medicine, Stony Brook, NY
| | - Nils Bäck
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Richard Mains
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT
| | - Louis Hodgson
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY
| | - Herbert Tanowitz
- Departments of Pathology, Medicine, Albert Einstein College of Medicine, Bronx, NY
| | | | - Betty Eipper
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT
| | - Regina Kuliawat
- Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY
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17
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MicroRNA 199a-5p Attenuates Retrograde Transport and Protects against Toxin-Induced Inhibition of Protein Biosynthesis. Mol Cell Biol 2018; 38:MCB.00548-17. [PMID: 29555727 DOI: 10.1128/mcb.00548-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 03/08/2018] [Indexed: 01/09/2023] Open
Abstract
Retrograde transport (RT) allows cells to retrieve receptors and other cellular cargoes for delivery to the Golgi apparatus, contributing to the maintenance of cellular homeostasis. This transport route is also commonly used by several bacterial toxins to exert their deleterious actions on eukaryotic cells. While the retrograde transport process has been well characterized, the contribution of microRNAs (miRNAs) in regulating this cellular transport mechanism remains unknown. Here, we determined that mir-199a and mir-199b, members of the intronic miRNA family, coordinate genes regulating RT and endosome trafficking. We demonstrate that miR-199a-5p attenuates the expression of Vps26A, Rab9B, and M6PR, thereby controlling RT from endosomes to the trans-Golgi network (TGN). Importantly, we found that overexpression of a Vps26A construct resistant to the inhibitory action of miR-199a-5p abrogates the effect of miR-199a-5p on RT. Finally, we demonstrate that miR-199-5p overexpression attenuates Shiga toxin type 1 (Stx1)-mediated inhibition of protein biosynthesis. In summary, our work identifies the first noncoding RNA that influences RT and reduces the inhibition of protein biosynthesis caused by bacterial toxins.
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Molecular regulation of insulin granule biogenesis and exocytosis. Biochem J 2017; 473:2737-56. [PMID: 27621482 DOI: 10.1042/bcj20160291] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 04/19/2016] [Indexed: 12/15/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by hyperglycemia, insulin resistance and hyperinsulinemia in early disease stages but a relative insulin insufficiency in later stages. Insulin, a peptide hormone, is produced in and secreted from pancreatic β-cells following elevated blood glucose levels. Upon its release, insulin induces the removal of excessive exogenous glucose from the bloodstream primarily by stimulating glucose uptake into insulin-dependent tissues as well as promoting hepatic glycogenesis. Given the increasing prevalence of T2DM worldwide, elucidating the underlying mechanisms and identifying the various players involved in the synthesis and exocytosis of insulin from β-cells is of utmost importance. This review summarizes our current understanding of the route insulin takes through the cell after its synthesis in the endoplasmic reticulum as well as our knowledge of the highly elaborate network that controls insulin release from the β-cell. This network harbors potential targets for anti-diabetic drugs and is regulated by signaling cascades from several endocrine systems.
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Riaz S, Zeidan A, Mraiche F. Myocardial proteases and cardiac remodeling. J Cell Physiol 2017; 232:3244-3250. [PMID: 28255990 DOI: 10.1002/jcp.25884] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 02/28/2017] [Indexed: 12/22/2022]
Abstract
Cardiac hypertrophy (CH), characterized by the enlargement of cardiomyocytes, fibrosis and apoptosis, is one of the leading causes of death worldwide. Despite the advances in cardiovascular research, there remains a need to further investigate the signaling pathways that mediate CH in order to identify novel therapeutic targets. One of the hallmarks of CH is the remodeling of the extracellular matrix (ECM). Multiple studies have shown an important role of cysteine proteases and matrix metalloproteinases (MMPs) in the remodeled heart. This review focuses on the role of cysteine cathepins and MMPs in cardiac remodeling.
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Affiliation(s)
- Sadaf Riaz
- College of Pharmacy, Qatar University, Doha, Qatar
| | - Asad Zeidan
- Faculty of Medicine, Department of Anatomy, Cell Biology and Physiology, American University of Beirut, Beirut, Lebanon
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Kaur H, Sparvoli D, Osakada H, Iwamoto M, Haraguchi T, Turkewitz AP. An endosomal syntaxin and the AP-3 complex are required for formation and maturation of candidate lysosome-related secretory organelles (mucocysts) in Tetrahymena thermophila. Mol Biol Cell 2017; 28:1551-1564. [PMID: 28381425 PMCID: PMC5449153 DOI: 10.1091/mbc.e17-01-0018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/22/2017] [Accepted: 03/28/2017] [Indexed: 12/14/2022] Open
Abstract
Lysosome-related organelles (LROs) are secretory organelles formed by convergence between secretory and endosomal trafficking pathways. In Tetrahymena, secretory vesicles that resemble dense core granules are a new class of LROs whose synthesis depends on a conserved syntaxin required for heterotypic fusion and AP-3 for maturation. The ciliate Tetrahymena thermophila synthesizes large secretory vesicles called mucocysts. Mucocyst biosynthesis shares features with dense core granules (DCGs) in animal cells, including proteolytic processing of cargo proteins during maturation. However, other molecular features have suggested relatedness to lysosome-related organelles (LROs). LROs, which include diverse organelles in animals, are formed via convergence of secretory and endocytic trafficking. Here we analyzed Tetrahymena syntaxin 7-like 1 (Stx7l1p), a Qa-SNARE whose homologues in other lineages are linked with vacuoles/LROs. Stx7l1p is targeted to both immature and mature mucocysts and is essential in mucocyst formation. In STX7L1-knockout cells, the two major classes of mucocyst cargo proteins localize independently, accumulating in largely nonoverlapping vesicles. Thus initial formation of immature mucocysts involves heterotypic fusion, in which a subset of mucocyst proteins is delivered via an endolysosomal compartment. Further, we show that subsequent maturation requires AP-3, a complex widely implicated in LRO formation. Knockout of the µ-subunit gene does not impede delivery of any known mucocyst cargo but nonetheless arrests mucocyst maturation. Our data argue that secretory organelles in ciliates may represent a new class of LROs and reveal key roles of an endosomal syntaxin and AP-3 in the assembly of this complex compartment.
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Affiliation(s)
- Harsimran Kaur
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Daniela Sparvoli
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Hiroko Osakada
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Masaaki Iwamoto
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Aaron P Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
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Hashimoto Y, Kondo C, Katunuma N. An Active 32-kDa Cathepsin L Is Secreted Directly from HT 1080 Fibrosarcoma Cells and Not via Lysosomal Exocytosis. PLoS One 2015; 10:e0145067. [PMID: 26674348 PMCID: PMC4684495 DOI: 10.1371/journal.pone.0145067] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 11/29/2015] [Indexed: 01/01/2023] Open
Abstract
Cathepsin L [EC 3.4.22.15] is secreted via lysosomal exocytosis by several types of cancer cells, including prostate and breast cancer cells. We previously reported that human cultured fibrosarcoma (HT 1080) cells secrete cathepsin L into the medium; this secreted cathepsin is 10-times more active than intracellular cathepsin. This increased activity was attributed to the presence of a 32-kDa cathepsin L in the medium. The aim of this study was to examine how this active 32-kDa cathepsin L is secreted into the medium. To this end, we compared the secreted active 32-kDa cathepsin L with lysosomal cathepsin L by using a novel gelatin zymography technique that employs leupeptin. We also examined the glycosylation and phosphorylation status of the proteins by using the enzymes endoglycosidase H [EC 3.2.1.96] and alkaline phosphatase [EC 3.1.3.1]. Strong active bands corresponding to the 32-kDa and 34-kDa cathepsin L forms were detected in the medium and lysosomes, respectively. The cell extract exhibited strong active bands for both forms. Moreover, both forms were adsorbed onto a concanavalin A-agarose column. The core protein domain of both forms had the same molecular mass of 30 kDa. The 32-kDa cathepsin L was phosphorylated, while the 34-kDa lysosomal form was dephosphorylated, perhaps because of the lysosomal marker enzyme, acid phosphatase. These results suggest that the active 32-kDa form does not enter the lysosomes. In conclusion, our results indicate that the active 32-kDa cathepsin L is secreted directly from the HT 1080 cells and not via lysosomal exocytosis.
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Affiliation(s)
- Yoko Hashimoto
- Department of Biochemistry, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan
- * E-mail:
| | - Chihiro Kondo
- Department of Biochemistry, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan
| | - Nobuhiko Katunuma
- Institute for Health Sciences, Tokushima Bunri University, Tokushima, Japan
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Hook G, Jacobsen JS, Grabstein K, Kindy M, Hook V. Cathepsin B is a New Drug Target for Traumatic Brain Injury Therapeutics: Evidence for E64d as a Promising Lead Drug Candidate. Front Neurol 2015; 6:178. [PMID: 26388830 PMCID: PMC4557097 DOI: 10.3389/fneur.2015.00178] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 07/31/2015] [Indexed: 12/22/2022] Open
Abstract
There is currently no therapeutic drug treatment for traumatic brain injury (TBI) despite decades of experimental clinical trials. This may be because the mechanistic pathways for improving TBI outcomes have yet to be identified and exploited. As such, there remains a need to seek out new molecular targets and their drug candidates to find new treatments for TBI. This review presents supporting evidence for cathepsin B, a cysteine protease, as a potentially important drug target for TBI. Cathepsin B expression is greatly up-regulated in TBI animal models, as well as in trauma patients. Importantly, knockout of the cathepsin B gene in TBI mice results in substantial improvements of TBI-caused deficits in behavior, pathology, and biomarkers, as well as improvements in related injury models. During the process of TBI-induced injury, cathepsin B likely escapes the lysosome, its normal subcellular location, into the cytoplasm or extracellular matrix (ECM) where the unleashed proteolytic power causes destruction via necrotic, apoptotic, autophagic, and activated glia-induced cell death, together with ECM breakdown and inflammation. Significantly, chemical inhibitors of cathepsin B are effective for improving deficits in TBI and related injuries including ischemia, cerebral bleeding, cerebral aneurysm, edema, pain, infection, rheumatoid arthritis, epilepsy, Huntington's disease, multiple sclerosis, and Alzheimer's disease. The inhibitor E64d is unique among cathepsin B inhibitors in being the only compound to have demonstrated oral efficacy in a TBI model and prior safe use in man and as such it is an excellent tool compound for preclinical testing and clinical compound development. These data support the conclusion that drug development of cathepsin B inhibitors for TBI treatment should be accelerated.
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Affiliation(s)
- Gregory Hook
- American Life Science Pharmaceuticals, Inc. , San Diego, CA , USA
| | | | - Kenneth Grabstein
- Department of Chemical Engineering, University of Washington , Seattle, WA , USA
| | - Mark Kindy
- Department of Neurosciences, Medical University of South Carolina , Charleston, SC , USA ; Ralph H. Johnson Veterans Administration Medical Center , Charleston, SC , USA
| | - Vivian Hook
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego , La Jolla, CA , USA ; Department of Neurosciences, Department of Pharmacology, University of California San Diego , La Jolla, CA , USA
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Osayi SN, Bloomston M, Schmidt CM, Ellison EC, Muscarella P. Biomarkers as predictors of recurrence following curative resection for pancreatic ductal adenocarcinoma: a review. BIOMED RESEARCH INTERNATIONAL 2014; 2014:468959. [PMID: 25050350 PMCID: PMC4094702 DOI: 10.1155/2014/468959] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 06/02/2014] [Accepted: 06/03/2014] [Indexed: 12/15/2022]
Abstract
Pancreatic ductal adenocarcinoma (PDA) is the fourth most common cancer causing death in the United States. Early tumor recurrence is an important contributor to the dismal prognosis. The availability of an accurate prognostic biomarker for predicting disease recurrence following curative resection will be beneficial for patient care. Most of the currently studied biomarkers remain in the investigational phase, with CA 19-9 being the only biomarker currently approved by the FDA. Herein, we review the utility of CA 19-9 and other investigational cellular, gene, and molecular tumor markers for predicting PDA recurrence following curative surgical resection.
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Affiliation(s)
- Sylvester N. Osayi
- Department of Surgery and Center for Minimally Invasive Surgery, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Mark Bloomston
- Department of Surgery and Center for Minimally Invasive Surgery, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Carl M. Schmidt
- Department of Surgery and Center for Minimally Invasive Surgery, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - E. Christopher Ellison
- Department of Surgery and Center for Minimally Invasive Surgery, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Peter Muscarella
- Department of Surgery and Center for Minimally Invasive Surgery, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
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24
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Fujita-Yoshigaki J, Matsuki-Fukushima M, Yokoyama M, Katsumata-Kato O. Sorting of a HaloTag protein that has only a signal peptide sequence into exocrine secretory granules without protein aggregation. Am J Physiol Gastrointest Liver Physiol 2013; 305:G685-96. [PMID: 24029466 DOI: 10.1152/ajpgi.00093.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The mechanism involved in the sorting and accumulation of secretory cargo proteins, such as amylase, into secretory granules of exocrine cells remains to be solved. To clarify that sorting mechanism, we expressed a reporter protein HaloTag fused with partial sequences of salivary amylase protein in primary cultured parotid acinar cells. We found that a HaloTag protein fused with only the signal peptide sequence (Met(1)-Ala(25)) of amylase, termed SS25H, colocalized well with endogenous amylase, which was confirmed by immunofluorescence microscopy. Percoll-density gradient centrifugation of secretory granule fractions shows that the distributions of amylase and SS25H were similar. These results suggest that SS25H is transported to secretory granules and is not discriminated from endogenous amylase by the machinery that functions to remove proteins other than granule cargo from immature granules. Another reporter protein, DsRed2, that has the same signal peptide sequence also colocalized with amylase, suggesting that the sorting to secretory granules is not dependent on a characteristic of the HaloTag protein. Whereas Blue Native PAGE demonstrates that endogenous amylase forms a high-molecular-weight complex, SS25H does not participate in the complex and does not form self-aggregates. Nevertheless, SS25H was released from cells by the addition of a β-adrenergic agonist, isoproterenol, which also induces amylase secretion. These results indicate that addition of the signal peptide sequence, which is necessary for the translocation in the endoplasmic reticulum, is sufficient for the transportation and storage of cargo proteins in secretory granules of exocrine cells.
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Affiliation(s)
- Junko Fujita-Yoshigaki
- Dept. of Physiology, Nihon Univ., School of Dentistry at Matsudo, 2-870-1 Sakaecho-nishi, Matsudo, Chiba, 271-8587, Japan.
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Messenger SW, Thomas DDH, Falkowski MA, Byrne JA, Gorelick FS, Groblewski GE. Tumor protein D52 controls trafficking of an apical endolysosomal secretory pathway in pancreatic acinar cells. Am J Physiol Gastrointest Liver Physiol 2013; 305:G439-52. [PMID: 23868405 PMCID: PMC3761242 DOI: 10.1152/ajpgi.00143.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 07/12/2013] [Indexed: 01/31/2023]
Abstract
Zymogen granule (ZG) formation in acinar cells involves zymogen cargo sorting from trans-Golgi into immature secretory granules (ISGs). ISG maturation progresses by removal of lysosomal membrane and select content proteins, which enter endosomal intermediates prior to their apical exocytosis. Constitutive and stimulated secretion through this mechanism is termed the constitutive-like and minor-regulated pathways, respectively. However, the molecular components that control membrane trafficking within these endosomal compartments are largely unknown. We show that tumor protein D52 is highly expressed in endosomal compartments following pancreatic acinar cell stimulation and regulates apical exocytosis of an apically directed endolysosomal compartment. Secretion from the endolysosomal compartment was detected by cell-surface antigen labeling of lysosome-associated membrane protein LAMP1, which is absent from ZGs, and had incomplete overlap with surface labeling of synaptotagmin 1, a marker of ZG exocytosis. Although culturing (16-18 h) of isolated acinar cells is accompanied by a loss of secretory responsiveness, the levels of SNARE proteins necessary for ZG exocytosis were preserved. However, levels of endolysosomal proteins D52, EEA1, Rab5, and LAMP1 markedly decreased with culture. When D52 levels were restored by adenoviral delivery, the levels of these regulatory proteins and secretion of both LAMP1 (endolysosomal) and amylase was strongly enhanced. These secretory effects were absent in alanine and aspartate substitutions of serine 136, the major D52 phosphorylation site, and were inhibited by brefeldin A, which does not directly affect the ZG compartment. Our results indicate that D52 directly regulates apical endolysosomal secretion and are consistent with previous studies, suggesting that this pathway indirectly regulates ZG secretion of digestive enzymes.
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Affiliation(s)
- Scott W Messenger
- Univ. of Wisconsin, Dept. of Nutritional Sciences, 1415 Linden Dr., Madison, WI 53706.
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26
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Zhang Y, Lu YX, Liu J, Yang C, Feng QL, Xu WH. A regulatory pathway, ecdysone-transcription factor relish-cathepsin L, is involved in insect fat body dissociation. PLoS Genet 2013; 9:e1003273. [PMID: 23459255 PMCID: PMC3573115 DOI: 10.1371/journal.pgen.1003273] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 12/10/2012] [Indexed: 12/21/2022] Open
Abstract
Insect fat body is the organ for intermediary metabolism, comparable to vertebrate liver and adipose tissue. Larval fat body is disintegrated to individual fat body cells and then adult fat body is remodeled at the pupal stage. However, little is known about the dissociation mechanism. We find that the moth Helicoverpa armigera cathepsin L (Har-CL) is expressed heavily in the fat body and is released from fat body cells into the extracellular matrix. The inhibitor and RNAi experiments demonstrate that Har-CL functions in the fat body dissociation in H. armigera. Further, a nuclear protein is identified to be transcription factor Har-Relish, which was found in insect immune response and specifically binds to the promoter of Har-CL gene to regulate its activity. Har-Relish also responds to the steroid hormone ecdysone. Thus, the dissociation of the larval fat body is involved in the hormone (ecdysone)-transcription factor (Relish)-target gene (cathepsin L) regulatory pathway. Insect fat body is the intermediary metabolism organ and the main source of hemolymph components, and it is crucial for insect development and metamorphosis. However, molecular mechanism for the fat body remodeling is almost unknown other than in Drosophila melanogaster. A pupal diapause species the cotton bollworm, Helicoverpa armigera (Har), is a useful model to study individual or tissue remodeling, because larval fat body will remain integral in diapause-type pupae for months, whereas the dissociation of larval fat body will start on day 0 after pupation in nondiapause-type ones. Here, we find that H. armigera cathepsin L (Har-CL) is released from fat body cells into the extracellular matrix for tissue dissociation. A nuclear protein is identified to be transcription factor Har-Relish, which regulates the promoter activity of Har-CL gene. Har-Relish also responds to the steroid hormone ecdysone. Thus, a new regulatory mechanism, ecdysone-Relish-cathepsin L signaling pathway, is involved in the larval fat body dissociation.
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Affiliation(s)
- Yao Zhang
- State Key Laboratory of Biocontrol and Institute of Entomology, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Yu-Xuan Lu
- State Key Laboratory of Biocontrol and Institute of Entomology, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Jian Liu
- Department of Life Sciences, School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, China
| | - Cui Yang
- State Key Laboratory of Biocontrol and Institute of Entomology, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Qi-Li Feng
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Wei-Hua Xu
- State Key Laboratory of Biocontrol and Institute of Entomology, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
- * E-mail:
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Pols MS, van Meel E, Oorschot V, ten Brink C, Fukuda M, Swetha MG, Mayor S, Klumperman J. hVps41 and VAMP7 function in direct TGN to late endosome transport of lysosomal membrane proteins. Nat Commun 2013; 4:1361. [PMID: 23322049 DOI: 10.1038/ncomms2360] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 12/05/2012] [Indexed: 12/18/2022] Open
Abstract
Targeted delivery of lysosome-associated membrane proteins is important for lysosome stability and function. Here we identify a pathway for transport of lysosome-associated membrane proteins directly from the trans-Golgi network to late endosomes, which exists in parallel to mannose 6-phosphate receptor and clathrin-dependent transport of lysosomal enzymes to early endosomes. By immunoelectron microscopy we localized endogenous LAMP-1 and -2 as well as LAMP-1-mGFP to non-coated, biosynthetic carriers at the trans-Golgi network and near late endosomes. These LAMP carriers were negative for mannose 6-phosphate receptor, adaptor-protein complex-1, secretory albumin and endocytic markers, but contained the homotypic fusion and protein sorting complex component hVps41 and the soluble N-ethylmaleimide-sensitive factor attachment protein receptors protein VAMP7. Knockdown of hVps41 or VAMP7 resulted in the accumulation of lysosome-associated membrane protein carriers, whereas knockdown of hVps39 or hVps18 did not, indicating that the effect of hVps41 is independent of CORVET/HOPS. Mannose 6-phosphate receptor carriers remained unaffected upon hVps41 or VAMP7 knockdown, implicating that hVps41 and VAMP7 are specifically involved in the fusion of trans-Golgi network-derived lysosome-associated membrane protein carriers with late endosomes.
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Affiliation(s)
- Maaike S Pols
- Department of Cell Biology, University Medical Centre Utrecht, AZU Room H02.313, Heidelberglaan 100, Utrecht 3584 CX, The Netherlands
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Haataja L, Snapp E, Wright J, Liu M, Hardy AB, Wheeler MB, Markwardt ML, Rizzo M, Arvan P. Proinsulin intermolecular interactions during secretory trafficking in pancreatic β cells. J Biol Chem 2012; 288:1896-906. [PMID: 23223446 DOI: 10.1074/jbc.m112.420018] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Classically, exit from the endoplasmic reticulum (ER) is rate-limiting for secretory protein trafficking because protein folding/assembly occurs there. In this study, we have exploited "hPro-CpepSfGFP," a human proinsulin bearing "superfolder" green fluorescent C-peptide expressed in pancreatic β cells where it is processed to human insulin and CpepSfGFP. Remarkably, steady-state accumulation of hPro-CpepSfGFP and endogenous proinsulin is in the Golgi region, as if final stages of protein folding/assembly were occurring there. The Golgi regional distribution of proinsulin is dynamic, influenced by fasting/refeeding, and increased with β cell zinc deficiency. However, coexpression of ER-entrapped mutant proinsulin-C(A7)Y shifts the steady-state distribution of wild-type proinsulin to the ER. Endogenous proinsulin coprecipitates with hPro-CpepSfGFP and even more so with hProC(A7)Y-CpepSfGFP. Using Cerulean and Venus-tagged proinsulins, we find that both WT-WT and WT-mutant proinsulin pairs exhibit FRET. The data demonstrate that wild-type proinsulin dimerizes within the ER but accumulates at a poorly recognized slow step within the Golgi region, reflecting either slow kinetics of proinsulin hexamerization, steps in formation of nascent secretory granules, or other unknown molecular events. However, in the presence of ongoing misfolding of a subpopulation of proinsulin in β cells, the rate-limiting step in transport of the remaining proinsulin shifts to the ER.
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Affiliation(s)
- Leena Haataja
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical School, Ann Arbor, Michigan 48105, USA
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29
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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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30
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Cheng XW, Shi GP, Kuzuya M, Sasaki T, Okumura K, Murohara T. Role for cysteine protease cathepsins in heart disease: focus on biology and mechanisms with clinical implication. Circulation 2012; 125:1551-62. [PMID: 22451605 DOI: 10.1161/circulationaha.111.066712] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Xian Wu Cheng
- Department of Cardiology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Nagoya, Japan.
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31
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Schvartz D, Brunner Y, Couté Y, Foti M, Wollheim CB, Sanchez JC. Improved characterization of the insulin secretory granule proteomes. J Proteomics 2012; 75:4620-31. [PMID: 22569486 DOI: 10.1016/j.jprot.2012.04.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 02/22/2012] [Accepted: 04/20/2012] [Indexed: 11/15/2022]
Abstract
Insulin secretory granules (ISGs) are pivotal organelles of pancreatic ß-cells and represent a key participant to glucose homeostasis. Indeed, insulin is packed and processed within these vesicles before its release by exocytosis. It is therefore crucial to acquire qualitative and quantitative data on the ISG proteome, in order to increase our knowledge on ISG biogenesis, maturation and exocytosis. Despites efforts made in the past years, the coverage of the ISG proteome is still incomplete and comprises many potential protein contaminants most likely coming from suboptimal sample preparations. We developed here a 3-step gradient purification procedure combined to Stable Isotope Labeling with Amino acids in Cell culture (SILAC) to further characterize the ISG protein content. Our results allowed to build three complementary proteomes containing 1/ proteins which are enriched in mature ISGs, 2/ proteins sharing multiple localizations including ISGs, and finally 3/ proteins sorted out from immature ISGs and/or co-purifying contaminants. As a proof of concept, the ProSAAS, a neuronal protein found in ISGs was further characterized and its granular localization proved. ProSAAS might represent a novel potential target allowing to better understand the defaults in insulin processing and secretion observed during type 2 diabetes progression. This article is part of a special issue entitled: Translational Proteomics.
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Affiliation(s)
- Domitille Schvartz
- Biomedical Proteomics Research Group, Department of Human Protein Sciences, University Medical Center, Geneva, Switzerland
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32
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Hook G, Hook V, Kindy M. The cysteine protease inhibitor, E64d, reduces brain amyloid-β and improves memory deficits in Alzheimer's disease animal models by inhibiting cathepsin B, but not BACE1, β-secretase activity. J Alzheimers Dis 2012; 26:387-408. [PMID: 21613740 DOI: 10.3233/jad-2011-110101] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cysteine protease cathepsin B is a potential drug target for reducing brain amyloid-β (Aβ) and improving memory in Alzheimer's disease (AD), as reduction of cathepsin B in transgenic mice expressing human wild-type amyloid-β protein precursor (AβPP) results in significantly decreased brain Aβ. Cathepsin B cleaves the wild-type β-secretase site sequence in AβPP to produce Aβ, and cathepsin B inhibitors administered to animal models expressing AβPP containing the wild-type β-secretase site sequence reduce brain Aβ in a manner consistent with β-secretase inhibition. But such inhibitors could act either by direct inhibition of cathepsin B β-secretase activity or by off-target inhibition of the other β-secretase, the aspartyl protease BACE1. To evaluate that issue, we orally administered a cysteine protease inhibitor, E64d, to normal guinea pigs or transgenic mice expressing human AβPP, both of which express the human wild-type β-secretase site sequence. In guinea pigs, oral E64d administration caused a dose-dependent reduction of up to 92% in brain, CSF, and plasma of Aβ40 and Aβ42, a reduction of up to 50% in the C-terminal β-secretase fragment (CTFβ), and a 91% reduction in brain cathepsin B activity, but increased brain BACE1 activity by 20%. In transgenic AD mice, oral E64d administration improved memory deficits and reduced brain Aβ40 and Aβ42, amyloid plaque, brain CTFβ, and brain cathepsin B activity, but increased brain BACE1 activity. We conclude that E64d likely reduces brain Aβ by inhibiting cathepsin B and not BACE1 β-secretase activity and that E64d therefore may have potential for treating AD patients.
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Affiliation(s)
- Gregory Hook
- American Life Science Pharmaceuticals, San Diego, CA 92109, USA.
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Cellular Mechanisms for the Biogenesis and Transport of Synaptic and Dense-Core Vesicles. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 299:27-115. [DOI: 10.1016/b978-0-12-394310-1.00002-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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34
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Abstract
Since its first visualization in 1898, the Golgi has been a topic of intense morphological research. A typical mammalian Golgi consists of a pile of stapled cisternae, the Golgi stack, which is a key station for modification of newly synthesized proteins and lipids. Distinct stacks are interconnected by tubules to form the Golgi ribbon. At the entrance site of the Golgi, the cis-Golgi, vesicular tubular clusters (VTCs) form the intermediate between the endoplasmic reticulum and the Golgi stack. At the exit site of the Golgi, the trans-Golgi, the trans-Golgi network (TGN) is the major site of sorting proteins to distinct cellular locations. Golgi functioning can only be understood in light of its complex architecture, as was revealed by a range of distinct electron microscopy (EM) approaches. In this article, a general concept of mammalian Golgi architecture, including VTCs and the TGN, is described.
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Affiliation(s)
- Judith Klumperman
- Department of Cell Biology, University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, The Netherlands.
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35
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Abstract
Insulin is a small but beautifully organized protein with a unique two-chain structure, the first protein to be sequenced. The mechanism of its biosynthesis invited much initial speculation but was finally clarified by the discovery of proinsulin, its single-chain precursor. The rich present-day field of protein precursor processing via post-translational proteolysis within the secretory pathway arose in the early 1970s as an offshoot of studies on insulin biosynthesis, which provided a novel paradigm for the generation of many other small neuroendocrine peptides. Before long, this mechanism was also found to play a role in the production of a much wider spectrum of proteins traversing the secretory pathway (receptors, growth factors, blood-clotting components, and even many viral envelope proteins) occurring in almost all eukaryotic cells. Indeed, yeast provided a key clue in the search for the proprotein convertases, the endoproteases that work along with carboxypeptidases and other modifying enzymes, such as the amidating enzyme complex (PAM), in converting inactive or less active precursor proteins into their fully active peptide products. In this "Reflections" article, I have tried to recount the people and events in my life that led to my involvement first in basic biochemical research and then on to insulin, proinsulin, and many relevant related areas that continue to fascinate and challenge my colleagues and me, as well as many other biomedical scientists today, as diabetes mellitus increasingly threatens human health throughout our contemporary world.
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Affiliation(s)
- Donald F Steiner
- Department of Medicine, University of Chicago, Chicago, Illinois 60637, USA.
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Boonen M, van Meel E, Oorschot V, Klumperman J, Kornfeld S. Vacuolization of mucolipidosis type II mouse exocrine gland cells represents accumulation of autolysosomes. Mol Biol Cell 2011; 22:1135-47. [PMID: 21325625 PMCID: PMC3078071 DOI: 10.1091/mbc.e10-07-0584] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 01/10/2011] [Accepted: 02/07/2010] [Indexed: 11/11/2022] Open
Abstract
We previously reported that mice deficient in UDP-GlcNAc:lysosomal enzyme GlcNAc-1-phosphotransferase (mucolipidosis type II or Gnptab -/- mice), the enzyme that initiates the addition of the mannose 6-phosphate lysosomal sorting signal on acid hydrolases, exhibited extensive vacuolization of their exocrine gland cells, while the liver, brain, and muscle appeared grossly unaffected. Similar pathological findings were observed in several exocrine glands of patients with mucolipidosis II. To understand the basis for this cell type-specific abnormality, we analyzed these tissues in Gnptab -/- mice using a combined immunoelectron microscopy and biochemical approach. We demonstrate that the vacuoles in the exocrine glands are enlarged autolysosomes containing undigested cytoplasmic material that accumulate secondary to deficient lysosomal function. Surprisingly, the acid hydrolase levels in these tissues ranged from normal to modestly decreased, in contrast to skin fibroblasts, which accumulate enlarged lysosomes and/or autolysosomes also but exhibit very low levels of acid hydrolases. We propose that the lysosomal defect in the exocrine cells is caused by the combination of increased secretion of the acid hydrolases via the constitutive pathway along with their entrapment in secretory granules. Taken together, our results provide new insights into the mechanisms of the tissue-specific abnormalities seen in mucolipidosis type II.
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Affiliation(s)
- Marielle Boonen
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - Eline van Meel
- Department of Cell Biology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
| | - Viola Oorschot
- Department of Cell Biology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
| | - Judith Klumperman
- Department of Cell Biology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
| | - Stuart Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110
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Liu M, Hodish I, Haataja L, Lara-Lemus R, Rajpal G, Wright J, Arvan P. Proinsulin misfolding and diabetes: mutant INS gene-induced diabetes of youth. Trends Endocrinol Metab 2010; 21:652-9. [PMID: 20724178 PMCID: PMC2967602 DOI: 10.1016/j.tem.2010.07.001] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 07/07/2010] [Accepted: 07/08/2010] [Indexed: 12/23/2022]
Abstract
Type 1B diabetes (typically with early onset and without islet autoantibodies) has been described in patients bearing small coding sequence mutations in the INS gene. Not all mutations in the INS gene cause the autosomal dominant Mutant INS-gene Induced Diabetes of Youth (MIDY) syndrome, but most missense mutations affecting proinsulin folding produce MIDY. MIDY patients are heterozygotes, with the expressed mutant proinsulins exerting dominant-negative (toxic gain of function) behavior in pancreatic beta cells. Here we focus primarily on proinsulin folding in the endoplasmic reticulum, providing insight into perturbations of this folding pathway in MIDY. Accumulated evidence indicates that, in the molecular pathogenesis of the disease, misfolded proinsulin exerts dominant effects that initially inhibit insulin production, progressing to beta cell demise with diabetes.
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Affiliation(s)
| | | | | | | | | | | | - Peter Arvan
- To whom correspondence may be addressed: Division of Metabolism, Endocrinology & Diabetes University of Michigan, 5560 MSRB2 1150 W. Medical Center Drive Ann Arbor, MI 48109-0678 Telephone: 734-936-5006 FAX: 734-936-6684
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Sobota JA, Bäck N, Eipper BA, Mains RE. Inhibitors of the V0 subunit of the vacuolar H+-ATPase prevent segregation of lysosomal- and secretory-pathway proteins. J Cell Sci 2009; 122:3542-53. [PMID: 19737820 DOI: 10.1242/jcs.034298] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vacuolar H(+)-ATPase (V-ATPase) establishes pH gradients along secretory and endocytic pathways. Progressive acidification is essential for proteolytic processing of prohormones and aggregation of soluble content proteins. The V-ATPase V(0) subunit is thought to have a separate role in budding and fusion events. Prolonged treatment of professional secretory cells with selective V-ATPase inhibitors (bafilomycin A1, concanamycin A) was used to investigate its role in secretory-granule biogenesis. As expected, these inhibitors eliminated regulated secretion and blocked prohormone processing. Drug treatment caused the formation of large, mixed organelles, with components of immature granules and lysosomes and some markers of autophagy. Markers of the trans-Golgi network and earlier secretory pathway were unaffected. Ammonium chloride and methylamine treatment blocked acidification to a similar extent as the V-ATPase inhibitors without producing mixed organelles. Newly synthesized granule content proteins appeared in mixed organelles, whereas mature secretory granules were spared. Following concanamycin treatment, selected membrane proteins enter tubulovesicular structures budding into the interior of mixed organelles. shRNA-mediated knockdown of the proteolipid subunit of V(0) also caused vesiculation of immature granules. Thus, V-ATPase has a role in protein sorting in immature granules that is distinct from its role in acidification.
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Affiliation(s)
- Jacqueline A Sobota
- Neuroscience Department, University of Connecticut Health Center, Farmington, CT 06030, USA
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Vogel P, Payne BJ, Read R, Lee WS, Gelfman CM, Kornfeld S. Comparative pathology of murine mucolipidosis types II and IIIC. Vet Pathol 2009; 46:313-24. [PMID: 19261645 PMCID: PMC2705191 DOI: 10.1354/vp.46-2-313] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
UDP-GlcNAc: lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase) is an alpha(2)beta(2)gamma(2) hexameric enzyme that catalyzes the first step in the synthesis of the mannose 6-phosphate targeting signal on lysosomal hydrolases. In humans, mutations in the gene encoding the alpha/beta subunit precursor give rise to mucolipidosis II (MLII), whereas mutations in the gene encoding the gamma subunit cause the less severe mucolipidosis IIIC (MLIIIC). In this study we describe the phenotypic, histologic, and serum lysosomal enzyme abnormalities in knockout mice lacking the gamma subunit and compare these findings to those of mice lacking the alpha/beta subunits and humans with MLII and MLIIIC. We found that both lines of mutant mice had elevated levels of serum lysosomal enzymes and cytoplasmic alterations in secretory cells of several exocrine glands; however, lesions in gamma-subunit deficient (Gnptg(-/-)) mice were milder and more restricted in distribution than in alpha/beta-subunit deficient (Gnptab(-/-)) mice. We found that onset, extent, and severity of lesions that developed in these two different knockouts correlated with measured lysosomal enzyme activity; with a more rapid, widespread, and severe storage disease phenotype developing in Gnptab(-/-) mice. In contrast to mice deficient in the alpha/beta subunits, the mice lacking the gamma subunits were of normal size, lacked cartilage defects, and did not develop retinal degeneration. The milder disease in the gamma-subunit deficient mice correlated with residual synthesis of the mannose 6-phosphate recognition marker. Of significance, neither strain of mutant mice developed cytoplasmic vacuolar inclusions in fibrocytes or mesenchymal cells (I-cells), the characteristic lesion associated with the prominent skeletal and connective tissue abnormalities in humans with MLII and MLIII. Instead, the predominant lesions in both lines of mice were found in the secretory epithelial cells of several exocrine glands, including the pancreas, and the parotid, submandibular salivary, nasal, lacrimal, bulbourethral, and gastric glands. The absence of retinal and chondrocyte lesions in Gnptg(-/-) mice might be attributed to residual beta-glucuronidase activity. We conclude that mice lacking either alpha/beta or gamma subunits displayed clinical and pathologic features that differed substantially from those reported in humans having mutations in orthologous genes.
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Affiliation(s)
- P Vogel
- Lexicon Pharmaceuticals, Pathology Department, 8800 Technology Forest Place, The Woodlands, TX 77381-1160, USA.
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40
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Abstract
Acute insulin secretion from stimulated pancreatic beta-cells is derived from the intracellular pool of insulin secretory granules wherein insulin is packaged in a highly concentrated (and in some species, crystalline) state. Here we review experimental work, principally from our laboratory, on the question of biogenesis of mature secretory granules within the broader context of intracellular protein trafficking. Events occurring in the lumen of organelles at various stages of intracellular transport within the secretory pathway and events at the limiting membrane of newly forming secretory granules each contribute to formation of the insulin storage compartment comprising the readily releasable pool.
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Affiliation(s)
- Peter Arvan
- Divisions of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA.
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41
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Biogenesis of Dense-Core Secretory Granules. TRAFFICKING INSIDE CELLS 2009. [PMCID: PMC7122546 DOI: 10.1007/978-0-387-93877-6_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dense core granules (DCGs) are vesicular organelles derived from outbound traffic through the eukaryotic secretory pathway. As DCGs are formed, the secretory pathway can also give rise to other types of vesicles, such as those bound for endosomes, lysosomes, and the cell surface. DCGs differ from these other vesicular carriers in both content and function, storing highly concentrated cores’ of condensed cargo in vesicles that are stably maintained within the cell until a specific extracellular stimulus causes their fusion with the plasma membrane. These unique features are imparted by the activities of membrane and lumenal proteins that are specifically delivered to the vesicles during synthesis. This chapter will describe the DCG biogenesis pathway, beginning with the sorting of DCG proteins from proteins that are destined for other types of vesicle carriers. In the trans-Golgi network (TGN), sorting occurs as DCG proteins aggregate, causing physical separation from non-DCG proteins. Recent work addresses the nature of interactions that produce these aggregates, as well as potentially important interactions with membranes and membrane proteins. DCG proteins are released from the TGN in vesicles called immature secretory granules (ISGs). The mechanism of ISG formation is largely unclear but is not believed to rely on the assembly of vesicle coats like those observed in other secretory pathways. The required cytosolic factors are now beginning to be identified using in vitro systems with purified cellular components. ISG transformation into a mature fusion-competent, stimulus-dependent DCG occurs as endoproteolytic processing of many DCG proteins causes continued condensation of the lumenal contents. At the same time, proteins that fail to be incorporated into the condensing core are removed by a coat-mediated budding mechanism, which also serves to remove excess membrane and membrane proteins from the maturing vesicle. This chapter will summarize the work leading to our current view of granule synthesis, and will discuss questions that need to be addressed in order to gain a more complete understanding of the pathway.
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Izagirre U, Angulo E, Wade SC, ap Gwynn I, Marigómez I. β-Glucuronidase and hexosaminidase are marker enzymes for different compartments of the endo-lysosomal system in mussel digestive cells. Cell Tissue Res 2008; 335:441-54. [DOI: 10.1007/s00441-008-0693-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Accepted: 09/02/2008] [Indexed: 10/21/2022]
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Park JJ, Loh YP. How peptide hormone vesicles are transported to the secretion site for exocytosis. Mol Endocrinol 2008; 22:2583-95. [PMID: 18669645 DOI: 10.1210/me.2008-0209] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Post-Golgi transport of peptide hormone-containing vesicles from the site of genesis at the trans-Golgi network to the release site at the plasma membrane is essential for activity-dependent hormone secretion to mediate various endocrinological functions. It is known that these vesicles are transported on microtubules to the proximity of the release site, and they are then loaded onto an actin/myosin system for distal transport through the actin cortex to just below the plasma membrane. The vesicles are then tethered to the plasma membrane, and a subpopulation of them are docked and primed to become the readily releasable pool. Cytoplasmic tails of vesicular transmembrane proteins, as well as many cytosolic proteins including adaptor proteins, motor proteins, and guanosine triphosphatases, are involved in vesicle budding, the anchoring of the vesicles, and the facilitation of movement along the transport systems. In addition, a set of cytosolic proteins is also necessary for tethering/docking of the vesicles to the plasma membrane. Many of these proteins have been identified from different types of (neuro)endocrine cells. Here, we summarize the proteins known to be involved in the mechanisms of sorting various cargo proteins into regulated secretory pathway hormone-containing vesicles, movement of these vesicles along microtubules and actin filaments, and their eventual tethering/docking to the plasma membrane for hormone secretion.
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Affiliation(s)
- Joshua J Park
- Section on Cellular Neurobiology, National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland 20892, USA
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44
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Origins of the regulated secretory pathway. THE GOLGI APPARATUS 2008. [PMCID: PMC7121582 DOI: 10.1007/978-3-211-76310-0_30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modes of transport of soluble (or luminal) secretory proteins synthesized in the endoplasmic reticulum (ER) could be divided into two groups. The socalled constitutive secretory pathway (CSP) is common to all eukaryotic cells, constantly delivering constitutive soluble secretory proteins (CSSPs) linked to the rate of protein synthesis but largely independent of external stimuli. In regulated secretion, protein is sorted from the Golgi into storage/secretory granules (SGs) whose contents are released when stimuli trigger their final fusion with the plasma membrane (Hannah et al. 1999).
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45
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Hinz G, Colanesi S, Hillmer S, Rogers JC, Robinson DG. Localization of vacuolar transport receptors and cargo proteins in the Golgi apparatus of developing Arabidopsis embryos. Traffic 2007; 8:1452-64. [PMID: 17696967 DOI: 10.1111/j.1600-0854.2007.00625.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Using immunogold electron microscopy, we have investigated the relative distribution of two types of vacuolar sorting receptors (VSR) and two different types of lumenal cargo proteins, which are potential ligands for these receptors in the secretory pathway of developing Arabidopsis embryos. Interestingly, both cargo proteins are deposited in the protein storage vacuole, which is the only vacuole present during the bent-cotyledon stage of embryo development. Cruciferin and aleurain do not share the same pattern of distribution in the Golgi apparatus. Cruciferin is mainly detected in the cis and medial cisternae, especially at the rims where storage proteins aggregate into dense vesicles (DVs). Aleurain is found throughout the Golgi stack, particularly in the trans cisternae and trans Golgi network where clathrin-coated vesicles (CCVs) are formed. Nevertheless, aleurain was detected in both DV and CCV. VSR-At1, a VSR that recognizes N-terminal vacuolar sorting determinants (VSDs) of the NPIR type, localizes mainly to the trans Golgi and is hardly detectable in DV. Receptor homology-transmembrane-RING H2 domain (RMR), a VSR that recognizes C-terminal VSDs, has a distribution that is very similar to that of cruciferin and is found in DV. Our results do not support a role for VSR-At1 in storage protein sorting, instead RMR proteins because of their distribution similar to that of cruciferin in the Golgi apparatus and their presence in DV are more likely candidates. Aleurain, which has an NPIR motif and seems to be primarily sorted via VSR-At1 into CCV, also possesses putative hydrophobic sorting determinants at its C-terminus that could allow the additional incorporation of this protein into DV.
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Affiliation(s)
- Giselbert Hinz
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
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46
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Brunner Y, Couté Y, Iezzi M, Foti M, Fukuda M, Hochstrasser DF, Wollheim CB, Sanchez JC. Proteomics analysis of insulin secretory granules. Mol Cell Proteomics 2007; 6:1007-17. [PMID: 17317658 DOI: 10.1074/mcp.m600443-mcp200] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin secretory granules (ISGs) are cytoplasmic organelles of pancreatic beta-cells. They are responsible for the storage and secretion of insulin. To date, only about 30 different proteins have been clearly described to be associated with these organelles. However, data from two-dimensional gel electrophoresis analyses suggested that almost 150 different polypeptides might be present within ISGs. The elucidation of the identity and function of the ISG proteins by proteomics strategies would be of considerable help to further understand some of the underlying mechanisms implicated in ISG biogenesis and trafficking. Furthermore it should give the bases to the comprehension of impaired insulin secretion observed during diabetes. A proteomics analysis of an enriched insulin granule fraction from the rat insulin-secreting cell line INS-1E was performed. The efficacy of the fractionation procedure was assessed by Western blot and electron microscopy. Proteins of the ISG fraction were separated by SDS-PAGE, excised from consecutive gel slices, and tryptically digested. Peptides were analyzed by nano-LC-ESI-MS/MS. This strategy identified 130 different proteins that were classified into four structural groups including intravesicular proteins, membrane proteins, novel proteins, and other proteins. Confocal microscopy analysis demonstrated the association of Rab37 and VAMP8 with ISGs in INS-1E cells. In conclusion, the present study identified 130 proteins from which 110 are new proteins associated with ISGs. The elucidation of their role will further help in the understanding of the mechanisms governing impaired insulin secretion during diabetes.
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Affiliation(s)
- Yannick Brunner
- Biomedical Proteomics Research Group, University Medical Center, 1211 Geneva 4, Switzerland
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Hosaka M, Watanabe T, Yamauchi Y, Sakai Y, Suda M, Mizutani S, Takeuchi T, Isobe T, Izumi T. A subset of p23 localized on secretory granules in pancreatic beta-cells. J Histochem Cytochem 2006; 55:235-45. [PMID: 17101722 DOI: 10.1369/jhc.6a7093.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Proteins on the membrane of secretory granules (SGs) involved in their biogenesis and exocytosis are poorly characterized compared with those of synaptic vesicle in neurons. Thus the secretory granule membrane was prepared from a mouse pancreatic beta-cell line MIN6 by subcellular fractionation, and protein constituents were analyzed by microscale two-dimensional liquid chromatography coupled with electrospray ionization tandem mass spectrometry. Using this proteomics approach, one of the p24 family proteins, p23, was unexpectedly found in the granule fraction, although p24 proteins are generally regarded as functioning in the early secretory pathways between the endoplasmic reticulum and the Golgi apparatus. We further showed that p23 is expressed at high levels in endocrine cells. Furthermore, immunocytochemical analyses of pancreatic beta-cells at the light and electron microscopic levels demonstrated that a significant amount of p23 is localized on the insulin granule membrane, although it is most intensely concentrated at the cis-Golgi compartment as previously shown in non-endocrine cells. These findings suggest that a fraction of p23 enters post-Golgi compartments and may function in the biogenesis and/or quality control of SGs.
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Affiliation(s)
- Masahiro Hosaka
- Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan
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48
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Sobota JA, Ferraro F, Bäck N, Eipper BA, Mains RE. Not all secretory granules are created equal: Partitioning of soluble content proteins. Mol Biol Cell 2006; 17:5038-52. [PMID: 17005911 PMCID: PMC1761688 DOI: 10.1091/mbc.e06-07-0626] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Secretory granules carrying fluorescent cargo proteins are widely used to study granule biogenesis, maturation, and regulated exocytosis. We fused the soluble secretory protein peptidylglycine alpha-hydroxylating monooxygenase (PHM) to green fluorescent protein (GFP) to study granule formation. When expressed in AtT-20 or GH3 cells, the PHM-GFP fusion protein partitioned from endogenous hormone (adrenocorticotropic hormone, growth hormone) into separate secretory granule pools. Both exogenous and endogenous granule proteins were stored and released in response to secretagogue. Importantly, we found that segregation of content proteins is not an artifact of overexpression nor peculiar to GFP-tagged proteins. Neither luminal acidification nor cholesterol-rich membrane microdomains play essential roles in soluble content protein segregation. Our data suggest that intrinsic biophysical properties of cargo proteins govern their differential sorting, with segregation occurring during the process of granule maturation. Proteins that can self-aggregate are likely to partition into separate granules, which can accommodate only a few thousand copies of any content protein; proteins that lack tertiary structure are more likely to distribute homogeneously into secretory granules. Therefore, a simple "self-aggregation default" theory may explain the little acknowledged, but commonly observed, tendency for both naturally occurring and exogenous content proteins to segregate from each other into distinct secretory granules.
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Affiliation(s)
- Jacqueline A. Sobota
- *Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401; and
| | - Francesco Ferraro
- *Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401; and
| | - Nils Bäck
- Department of Anatomy, Institute of Biomedicine, University of Helsinki, FIN-00014, Helsinki, Finland
| | - Betty A. Eipper
- *Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401; and
| | - Richard E. Mains
- *Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401; and
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Kim T, Gondré-Lewis MC, Arnaoutova I, Loh YP. Dense-core secretory granule biogenesis. Physiology (Bethesda) 2006; 21:124-33. [PMID: 16565478 DOI: 10.1152/physiol.00043.2005] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The dense-core secretory granule is a key organelle for secretion of hormones and neuropeptides in endocrine cells and neurons, in response to stimulation. Cholesterol and granins are critical for the assembly of these organelles at the trans-Golgi network, and their biogenesis is regulated quantitatively by posttranscriptional and posttranslational mechanisms.
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Affiliation(s)
- Taeyoon Kim
- Section on Cellular Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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Fujita-Yoshigaki J, Katsumata O, Matsuki M, Yoshigaki T, Furuyama S, Sugiya H. Difference in distribution of membrane proteins between low- and high-density secretory granules in parotid acinar cells. Biochem Biophys Res Commun 2006; 344:283-92. [PMID: 16630574 DOI: 10.1016/j.bbrc.2006.03.130] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Accepted: 03/17/2006] [Indexed: 10/24/2022]
Abstract
Secretory granules (SGs) are considered to be generated as immature granules and to mature by condensation of their contents. In this study, SGs of parotid gland were separated into low-, medium-, and high-density granule fractions by Percoll-density gradient centrifugation, since it was proposed that the density corresponds to the degree of maturation. The observation with electron microscopy showed that granules in the three fractions were very similar. The average diameter of high-density granules was a little but significantly larger than that of low-density granules. Although the three fractions contained amylase, suggesting that they are all SGs, distribution of membrane proteins was markedly different. Syntaxin6 and VAMP4 were localized in the low-density granule fraction, while VAMP2 was concentrated in the high-density granule fraction. Immunoprecipitation with anti-syntaxin6 antibody caused coprecipitation of VAMP2 from the medium-density granule fraction without solubilization, but not from Triton X-100-solubilized fraction, while VAMP4 was coprecipitated from both fractions. Therefore, VAMP2 is present on the same granules, but is separated from syntaxin6 and VAMP4, which are expected to be removed from immature granules. These results suggest that the medium-density granules are intermediates from low- to high-density granules, and that the membrane components of SGs dynamically change by budding and fusion during maturation.
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Affiliation(s)
- Junko Fujita-Yoshigaki
- Department of Physiology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan.
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