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Barker E, Morgan A, Barclay JW. Tissue distribution of cysteine string protein/DNAJC5 in C. elegans analysed by CRISPR/Cas9-mediated tagging of endogenous DNJ-14. Cell Tissue Res 2024; 396:41-55. [PMID: 38403745 PMCID: PMC10997724 DOI: 10.1007/s00441-024-03875-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 02/06/2024] [Indexed: 02/27/2024]
Abstract
Cysteine string protein (CSP) is a member of the DnaJ/Hsp40 family of molecular chaperones. CSP is enriched in neurons, where it mainly localises to synaptic vesicles. Mutations in CSP-encoding genes in flies, worms, mice and humans result in neuronal dysfunction, neurodegeneration and reduced lifespan. Most attention has therefore focused on CSP's neuronal functions, although CSP is also expressed in non-neuronal cells. Here, we used genome editing to fluorescently tag the Caenorhabditis elegans CSP orthologue, dnj-14, to identify which tissues preferentially express CSP and hence may contribute to the observed mutant phenotypes. Replacement of dnj-14 with wrmScarlet caused a strong chemotaxis defect, as seen with other dnj-14 null mutants. In contrast, inserting the reporter in-frame to create a DNJ-14-wrmScarlet fusion protein had no effect on chemotaxis, indicating that C-terminal tagging does not impair DNJ-14 function. WrmScarlet fluorescence appeared most obvious in the intestine, head/pharynx, spermathecae and vulva/uterus in the reporter strains, suggesting that DNJ-14 is preferentially expressed in these tissues. Crossing the DNJ-14-wrmScarlet strain with GFP marker strains confirmed the intestinal and pharyngeal expression, but only a partial overlap with neuronal GFP was observed. DNJ-14-wrmScarlet fluorescence in the intestine was increased in response to starvation, which may be relevant to mammalian CSPα's role in microautophagy. DNJ-14's enrichment in worm reproductive tissues (spermathecae and vulva/uterus) parallels the testis-specific expression of CSPβ and CSPγ isoforms in mammals. Furthermore, CSPα messenger RNA is highly expressed in the human proximal digestive tract, suggesting that CSP may have a conserved, but overlooked, function within the gastrointestinal system.
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Affiliation(s)
- Eleanor Barker
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St, Liverpool, L69 3BX, UK
- Current address: Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - Alan Morgan
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
| | - Jeff W Barclay
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
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2
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Lee J, Xu Y, Saidi L, Xu M, Zinsmaier K, Ye Y. Abnormal triaging of misfolded proteins by adult neuronal ceroid lipofuscinosis-associated DNAJC5/CSPα mutants causes lipofuscin accumulation. Autophagy 2023; 19:204-223. [PMID: 35506243 PMCID: PMC9809949 DOI: 10.1080/15548627.2022.2065618] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Mutations in DNAJC5/CSPα are associated with adult neuronal ceroid lipofuscinosis (ANCL), a dominant-inherited neurodegenerative disease featuring lysosome-derived autofluorescent storage materials (AFSMs) termed lipofuscin. Functionally, DNAJC5 has been implicated in chaperoning synaptic proteins and in misfolding-associated protein secretion (MAPS), but how DNAJC5 dysfunction causes lipofuscinosis and neurodegeneration is unclear. Here we report two functionally distinct but coupled chaperoning activities of DNAJC5, which jointly regulate lysosomal homeostasis: While endolysosome-associated DNAJC5 promotes ESCRT-dependent microautophagy, a fraction of perinuclear and non-lysosomal DNAJC5 mediates MAPS. Functional proteomics identifies a previously unknown DNAJC5 interactor SLC3A2/CD98hc that is essential for the perinuclear DNAJC5 localization and MAPS but dispensable for microautophagy. Importantly, uncoupling these two processes, as seen in cells lacking SLC3A2 or expressing ANCL-associated DNAJC5 mutants, generates DNAJC5-containing AFSMs resembling NCL patient-derived lipofuscin and induces neurodegeneration in a Drosophila ANCL model. These findings suggest that MAPS safeguards microautophagy to avoid DNAJC5-associated lipofuscinosis and neurodegeneration.Abbreviations: 3-MA: 3-methyladenine; ACTB: actin beta; AFSM: autofluorescent storage materials; ANCL: adult neuronal ceroid lipofuscinosis; Baf. A1: bafilomycin A1; CLN: ceroid lipofuscinosis neuronal; CLU: clusterin; CS: cysteine string domain of DNAJC5/CSPα; CUPS: compartment for unconventional protein secretion; DN: dominant negative; DNAJC5/CSPα: DnaJ heat shock protein family (Hsp40) member C5; eMI: endosomal microautophagy; ESCRT: endosomal sorting complex required for transport; GFP: green fluorescent protein; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; INCL: infant neuronal ceroid lipofuscinosis; JNCL: juvenile neuronal ceroid lipofuscinosis; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LAPTM4B: lysosomal protein transmembrane 4 beta; LN: linker domain of DNAJC5/CSPα; MAPS: misfolding-associated protein secretion; mCh/Ch: mCherry; mCi/Ci: mCitrine; MTOR: mechanistic target of rapamycin kinase; NCL: neuronal ceroid lipofuscinosis; PPT1: palmitoyl-protein thioesterase 1; PQC: protein quality control; SBP: streptavidin binding protein; SGT: small glutamine-rich tetratricopeptide repeat; shRNA: short hairpin RNA; SLC3A2/CD98hc: solute carrier family 3 member 2; SNCA/α-synuclein: synuclein alpha; TMED10: transmembrane p24 trafficking protein 10; UV: ultraviolet; VPS4: vacuolar protein sorting 4 homolog; WT: wild type.
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Affiliation(s)
- Juhyung Lee
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Yue Xu
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Layla Saidi
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Miao Xu
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Konrad Zinsmaier
- Departments of Neuroscience and Molecular and Cellular Biology, University of Arizona, Tucson, AZ, USA
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA,CONTACT Yihong Ye Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892, USA
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3
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Gundersen CB. Cysteine string proteins. Prog Neurobiol 2020; 188:101758. [DOI: 10.1016/j.pneurobio.2020.101758] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 01/06/2020] [Accepted: 01/13/2020] [Indexed: 12/17/2022]
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Research Progress on the Relationship Between Acute Pancreatitis and Calcium Overload in Acinar Cells. Dig Dis Sci 2019; 64:25-38. [PMID: 30284136 DOI: 10.1007/s10620-018-5297-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 09/01/2018] [Indexed: 02/07/2023]
Abstract
Acute pancreatitis is a human disease with multiple causes that leads to autodigestion of the pancreas. There is sufficient evidence to support the key role of sustained increase in cytosolic calcium concentrations in the early pathogenesis of the disease. To clarify the mechanism of maintaining calcium homeostasis in the cell and pathological processes caused by calcium overload would help to research directly targeted therapeutic agents. We will specifically review the following: intracellular calcium homeostasis and regulation, the occurrence of calcium overload in acinar cells, the role of calcium overload in the pathogenesis of AP, the treatment strategy proposed for calcium overload.
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5
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Lackie RE, Maciejewski A, Ostapchenko VG, Marques-Lopes J, Choy WY, Duennwald ML, Prado VF, Prado MAM. The Hsp70/Hsp90 Chaperone Machinery in Neurodegenerative Diseases. Front Neurosci 2017; 11:254. [PMID: 28559789 PMCID: PMC5433227 DOI: 10.3389/fnins.2017.00254] [Citation(s) in RCA: 232] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/20/2017] [Indexed: 12/12/2022] Open
Abstract
The accumulation of misfolded proteins in the human brain is one of the critical features of many neurodegenerative diseases, including Alzheimer's disease (AD). Assembles of beta-amyloid (Aβ) peptide—either soluble (oligomers) or insoluble (plaques) and of tau protein, which form neurofibrillary tangles, are the major hallmarks of AD. Chaperones and co-chaperones regulate protein folding and client maturation, but they also target misfolded or aggregated proteins for refolding or for degradation, mostly by the proteasome. They form an important line of defense against misfolded proteins and are part of the cellular quality control system. The heat shock protein (Hsp) family, particularly Hsp70 and Hsp90, plays a major part in this process and it is well-known to regulate protein misfolding in a variety of diseases, including tau levels and toxicity in AD. However, the role of Hsp90 in regulating protein misfolding is not yet fully understood. For example, knockdown of Hsp90 and its co-chaperones in a Caenorhabditis elegans model of Aβ misfolding leads to increased toxicity. On the other hand, the use of Hsp90 inhibitors in AD mouse models reduces Aβ toxicity, and normalizes synaptic function. Stress-inducible phosphoprotein 1 (STI1), an intracellular co-chaperone, mediates the transfer of clients from Hsp70 to Hsp90. Importantly, STI1 has been shown to regulate aggregation of amyloid-like proteins in yeast. In addition to its intracellular function, STI1 can be secreted by diverse cell types, including astrocytes and microglia and function as a neurotrophic ligand by triggering signaling via the cellular prion protein (PrPC). Extracellular STI1 can prevent Aβ toxic signaling by (i) interfering with Aβ binding to PrPC and (ii) triggering pro-survival signaling cascades. Interestingly, decreased levels of STI1 in C. elegans can also increase toxicity in an amyloid model. In this review, we will discuss the role of intracellular and extracellular STI1 and the Hsp70/Hsp90 chaperone network in mechanisms underlying protein misfolding in neurodegenerative diseases, with particular focus on AD.
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Affiliation(s)
- Rachel E Lackie
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada.,Program in Neuroscience, University of Western OntarioLondon, ON, Canada
| | - Andrzej Maciejewski
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada.,Department of Biochemistry, University of Western OntarioLondon, ON, Canada
| | - Valeriy G Ostapchenko
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada
| | - Jose Marques-Lopes
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada
| | - Wing-Yiu Choy
- Department of Biochemistry, University of Western OntarioLondon, ON, Canada
| | - Martin L Duennwald
- Department of Pathology and Laboratory Medicine, University of Western OntarioLondon, ON, Canada
| | - Vania F Prado
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada.,Program in Neuroscience, University of Western OntarioLondon, ON, Canada.,Department of Physiology and Pharmacology, University of Western OntarioLondon, ON, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western OntarioLondon, ON, Canada
| | - Marco A M Prado
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada.,Program in Neuroscience, University of Western OntarioLondon, ON, Canada.,Department of Physiology and Pharmacology, University of Western OntarioLondon, ON, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western OntarioLondon, ON, Canada
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6
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Fontaine SN, Zheng D, Sabbagh JJ, Martin MD, Chaput D, Darling A, Trotter JH, Stothert AR, Nordhues BA, Lussier A, Baker J, Shelton L, Kahn M, Blair LJ, Stevens SM, Dickey CA. DnaJ/Hsc70 chaperone complexes control the extracellular release of neurodegenerative-associated proteins. EMBO J 2016; 35:1537-49. [PMID: 27261198 PMCID: PMC4946142 DOI: 10.15252/embj.201593489] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 04/25/2016] [Accepted: 04/27/2016] [Indexed: 12/12/2022] Open
Abstract
It is now known that proteins associated with neurodegenerative disease can spread throughout the brain in a prionlike manner. However, the mechanisms regulating the trans-synaptic spread propagation, including the neuronal release of these proteins, remain unknown. The interaction of neurodegenerative disease-associated proteins with the molecular chaperone Hsc70 is well known, and we hypothesized that much like disaggregation, refolding, degradation, and even normal function, Hsc70 may dictate the extracellular fate of these proteins. Here, we show that several proteins, including TDP-43, α-synuclein, and the microtubule-associated protein tau, can be driven out of the cell by an Hsc70 co-chaperone, DnaJC5. In fact, DnaJC5 overexpression induced tau release in cells, neurons, and brain tissue, but only when activity of the chaperone Hsc70 was intact and when tau was able to associate with this chaperone. Moreover, release of tau from neurons was reduced in mice lacking the DnaJC5 gene and when the complement of DnaJs in the cell was altered. These results demonstrate that the dynamics of DnaJ/Hsc70 complexes are critically involved in the release of neurodegenerative disease proteins.
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Affiliation(s)
- Sarah N Fontaine
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA James A. Haley Veteran's Hospital, Tampa, FL, USA
| | - Dali Zheng
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - Jonathan J Sabbagh
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA James A. Haley Veteran's Hospital, Tampa, FL, USA
| | - Mackenzie D Martin
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA James A. Haley Veteran's Hospital, Tampa, FL, USA
| | - Dale Chaput
- Department of Cell, Molecular and Life Sciences, University of South Florida, Tampa, FL, USA
| | - April Darling
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - Justin H Trotter
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
| | - Andrew R Stothert
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - Bryce A Nordhues
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - April Lussier
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - Jeremy Baker
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - Lindsey Shelton
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - Mahnoor Kahn
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - Laura J Blair
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA
| | - Stanley M Stevens
- Department of Cell, Molecular and Life Sciences, University of South Florida, Tampa, FL, USA
| | - Chad A Dickey
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, USA James A. Haley Veteran's Hospital, Tampa, FL, USA
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7
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Mareninova OA, Sendler M, Malla SR, Yakubov I, French SW, Tokhtaeva E, Vagin O, Oorschot V, Lüllmann-Rauch R, Blanz J, Dawson D, Klumperman J, Lerch MM, Mayerle J, Gukovsky I, Gukovskaya AS. Lysosome associated membrane proteins maintain pancreatic acinar cell homeostasis: LAMP-2 deficient mice develop pancreatitis. Cell Mol Gastroenterol Hepatol 2015; 1:678-694. [PMID: 26693174 PMCID: PMC4673685 DOI: 10.1016/j.jcmgh.2015.07.006] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS The pathogenic mechanism of pancreatitis is poorly understood. Recent evidence implicates defective autophagy in pancreatitis responses; however, the pathways mediating impaired autophagy in pancreas remain largely unknown. Here, we investigate the role of lysosome associated membrane proteins (LAMPs) in pancreatitis. METHODS We analyzed changes in LAMPs in experimental models and human pancreatitis, and the underlying mechanisms: LAMP de-glycosylation and degradation. LAMP cleavage by cathepsin B (CatB) was analyzed by mass spectrometry. We used mice deficient in LAMP-2 to assess its role in pancreatitis. RESULTS Pancreatic levels of LAMP-1 and LAMP-2 greatly decrease across various pancreatitis models and in human disease. Pancreatitis does not trigger LAMPs' bulk de-glycosylation, but induces their degradation via CatB-mediated cleavage of LAMP molecule close to the boundary between luminal and transmembrane domains. LAMP-2 null mice spontaneously develop pancreatitis that begins with acinar cell vacuolization due to impaired autophagic flux, and progresses to severe pancreas damage characterized by trypsinogen activation, macrophage-driven inflammation, and acinar cell death. LAMP-2 deficiency causes a decrease in pancreatic digestive enzymes content, stimulates the basal and inhibits CCK-induced amylase secretion by acinar cells. The effects of LAMP-2 knockout and acute cerulein pancreatitis overlap, which corroborates the pathogenic role of LAMP decrease in experimental pancreatitis models. CONCLUSIONS The results indicate a critical role for LAMPs, particularly LAMP-2, in maintaining pancreatic acinar cell homeostasis, and provide evidence that defective lysosomal function, resulting in impaired autophagy, leads to pancreatitis. Mice with LAMP-2 deficiency present a novel genetic model of human pancreatitis caused by lysosomal/autophagic dysfunction.
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Affiliation(s)
- Olga A. Mareninova
- VA Greater Los Angeles Healthcare System, Los Angeles, California
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Matthias Sendler
- Department of Medicine A, University Medicine, Ernst-Moritz-Arndt University Greifswald, Greifswald, Germany
| | - Sudarshan Ravi Malla
- Department of Medicine A, University Medicine, Ernst-Moritz-Arndt University Greifswald, Greifswald, Germany
| | - Iskandar Yakubov
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | | | - Elmira Tokhtaeva
- VA Greater Los Angeles Healthcare System, Los Angeles, California
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Olga Vagin
- VA Greater Los Angeles Healthcare System, Los Angeles, California
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Viola Oorschot
- University Medical Center Utrecht, Utrecht, the Netherlands
- Monash Micro Imaging, Monash University, Melbourne, Victoria, Australia
| | | | - Judith Blanz
- Biochemical Institute, Christian-Albrechts-University Kiel, Kiel, Germany
| | - David Dawson
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | | | - Markus M. Lerch
- Department of Medicine A, University Medicine, Ernst-Moritz-Arndt University Greifswald, Greifswald, Germany
| | - Julia Mayerle
- Department of Medicine A, University Medicine, Ernst-Moritz-Arndt University Greifswald, Greifswald, Germany
| | - Ilya Gukovsky
- VA Greater Los Angeles Healthcare System, Los Angeles, California
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Anna S. Gukovskaya
- VA Greater Los Angeles Healthcare System, Los Angeles, California
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
- Correspondence Address correspondence to: Anna S. Gukovskaya, PhD, Pancreatic Research Group, West Los Angeles VA Healthcare Center, 11301 Wilshire Boulevard, Building 258, Room 340, Los Angeles, California 90073. fax: 310-268-4981.
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8
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Abstract
Synaptic vesicles release their vesicular contents to the extracellular space by Ca(2+)-triggered exocytosis. The Ca(2+)-triggered exocytotic process is regulated by synaptotagmin (Syt), a vesicular Ca(2+)-binding C2 domain protein. Synaptotagmin 1 (Syt1), the most studied major isoform among 16 Syt isoforms, mediates Ca(2+)-triggered synaptic vesicle exocytosis by interacting with the target membranes and SNARE/complexin complex. In synapses of the central nervous system, synaptobrevin 2, a major vesicular SNARE protein, forms a ternary SNARE complex with the plasma membrane SNARE proteins, syntaxin 1 and SNAP25. The affinities of Ca(2+)-dependent interactions between Syt1 and its targets (i.e., SNARE complexes and membranes) are well correlated with the efficacies of the corresponding exocytotic processes. Therefore, different SNARE protein isoforms and membrane lipids, which interact with Syt1 with various affinities, are capable of regulating the efficacy of Syt1-mediated exocytosis. Otoferlin, another type of vesicular C2 domain protein that binds to the membrane in a Ca(2+)-dependent manner, is also involved in the Ca(2+)-triggered synaptic vesicle exocytosis in auditory hair cells. However, the functions of otoferlin in the exocytotic process are not well understood. In addition, at least five different types of synaptic vesicle proteins such as synaptic vesicle protein 2, cysteine string protein α, rab3, synapsin, and a group of proteins containing four transmembrane regions, which includes synaptophysin, synaptogyrin, and secretory carrier membrane protein, are involved in modulating the exocytotic process by regulating the formation and trafficking of synaptic vesicles.
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Affiliation(s)
- Ok-Ho Shin
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas
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Donnelier J, Braun JEA. CSPα-chaperoning presynaptic proteins. Front Cell Neurosci 2014; 8:116. [PMID: 24808827 PMCID: PMC4010753 DOI: 10.3389/fncel.2014.00116] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 04/09/2014] [Indexed: 12/11/2022] Open
Abstract
Synaptic transmission relies on precisely regulated and exceedingly fast protein-protein interactions that involve voltage-gated channels, the exocytosis/endocytosis machinery as well as signaling pathways. Although we have gained an ever more detailed picture of synaptic architecture much remains to be learned about how synapses are maintained. Synaptic chaperones are “folding catalysts” that preserve proteostasis by regulating protein conformation (and therefore protein function) and prevent unwanted protein-protein interactions. Failure to maintain synapses is an early hallmark of several degenerative diseases. Cysteine string protein (CSPα) is a presynaptic vesicle protein and molecular chaperone that has a central role in preventing synaptic loss and neurodegeneration. Over the past few years, a number of different “client proteins” have been implicated as CSPα substrates including voltage-dependent ion channels, signaling proteins and proteins critical to the synaptic vesicle cycle. Here we review the ion channels and synaptic protein complexes under the influence of CSPα and discuss gaps in our current knowledge.
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Affiliation(s)
- Julien Donnelier
- Department of Physiology and Pharmacology, The Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary Calgary, AB, Canada
| | - Janice E A Braun
- Department of Physiology and Pharmacology, The Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary Calgary, AB, Canada
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10
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Truchet S, Chat S, Ollivier-Bousquet M. Milk secretion: The role of SNARE proteins. J Mammary Gland Biol Neoplasia 2014; 19:119-30. [PMID: 24264376 DOI: 10.1007/s10911-013-9311-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 11/13/2013] [Indexed: 12/21/2022] Open
Abstract
During lactation, polarized mammary epithelial secretory cells (MESCs) secrete huge quantities of the nutrient molecules that make up milk, i.e. proteins, fat globules and soluble components such as lactose and minerals. Some of these nutrients are only produced by the MESCs themselves, while others are to a great extent transferred from the blood. MESCs can thus be seen as a crossroads for both the uptake and the secretion with cross-talks between intracellular compartments that enable spatial and temporal coordination of the secretion of the milk constituents. Although the physiology of lactation is well understood, the molecular mechanisms underlying the secretion of milk components remain incompletely characterized. Major milk proteins, namely caseins, are secreted by exocytosis, while the milk fat globules are released by budding, being enwrapped by the apical plasma membrane. Prolactin, which stimulates the transcription of casein genes, also induces the production of arachidonic acid, leading to accelerated casein transport and/or secretion. Because of their ability to form complexes that bridge two membranes and promote their fusion, SNARE (Soluble N-ethylmaleimide-Sensitive Factor Attachment Protein Receptor) proteins are involved in almost all intracellular trafficking steps and exocytosis. As SNAREs can bind arachidonic acid, they could be the effectors of the secretagogue effect of prolactin in MESCs. Indeed, some SNAREs have been observed between secretory vesicles and lipid droplets suggesting that these proteins could not only orchestrate the intracellular trafficking of milk components but also act as key regulators for both the coupling and coordination of milk product secretion in response to hormones.
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Affiliation(s)
- Sandrine Truchet
- INRA, UR1196 Génomique et Physiologie de la Lactation, 78352, Jouy-en-Josas Cedex, France,
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11
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Characterization of cysteine string protein in rat parotid acinar cells. Arch Biochem Biophys 2013; 538:1-5. [DOI: 10.1016/j.abb.2013.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 07/28/2013] [Accepted: 08/01/2013] [Indexed: 11/20/2022]
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12
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Lerch MM, Gorelick FS. Models of acute and chronic pancreatitis. Gastroenterology 2013; 144:1180-93. [PMID: 23622127 DOI: 10.1053/j.gastro.2012.12.043] [Citation(s) in RCA: 287] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 12/06/2012] [Accepted: 12/13/2012] [Indexed: 12/16/2022]
Abstract
Animal models of acute and chronic pancreatitis have been created to examine mechanisms of pathogenesis, test therapeutic interventions, and study the influence of inflammation on the development of pancreatic cancer. In vitro models can be used to study early stage, short-term processes that involve acinar cell responses. Rodent models reproducibly develop mild or severe disease. One of the most commonly used pancreatitis models is created by administration of supraphysiologic concentrations of caerulein, an ortholog of cholecystokinin. Induction of chronic pancreatitis with factors thought to have a role in human disease, such as combinations of lipopolysaccharide and chronic ethanol feeding, might be relevant to human disease. Models of autoimmune chronic pancreatitis have also been developed. Most models, particularly of chronic pancreatitis, require further characterization to determine which features of human disease they include.
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Affiliation(s)
- Markus M Lerch
- Department of Medicine A, University Medicine Greifswald, Ferdinand-Sauerbruch-Strasse, Greifswald, Germany.
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13
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Perfringolysin O as a useful tool to study human sperm physiology. Fertil Steril 2013; 99:99-106.e2. [DOI: 10.1016/j.fertnstert.2012.08.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 08/09/2012] [Accepted: 08/22/2012] [Indexed: 11/27/2022]
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Bjaelde RG, Arnadottir SS, Leipziger J, Praetorius HA. Agonists that increase [Ca²⁺](i) halt the movement of acidic cytoplasmic vesicles in MDCK cells. J Membr Biol 2011; 244:43-53. [PMID: 21989951 DOI: 10.1007/s00232-011-9396-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Accepted: 09/23/2011] [Indexed: 11/30/2022]
Abstract
Translocation of vesicles within the cytoplasm is essential to normal cell function. The vesicles are typically transported along the microtubules to their destination. The aim of this study was to characterize the vesicular movement in resting and stimulated renal epithelial cells. MDCK cells loaded with either quinacrine or acridine orange, dyes taken up by acidic vesicles, were observed at 37°C in semiopen perfusion chambers. Time-lapse series were analyzed by Imaris software. Our data revealed vigorous movement of stained vesicles in resting MDCK cells. These movements seem to require intact microtubules because nocodazole leads to a considerable reduction of the vesicular movements. Interestingly, we found that extracellular ATP caused the vesicular movement to cease. This observation was obvious in time lapse. Similarly, other stimuli known to increase the intracellular Ca²⁺ concentration ([Ca²⁺](i)) in MDCK cells (increment in the fluid flow rate or arginine vasopressin) also reduced the vesicular movement. These findings were quantified by analysis of single vesicular movement patterns. In this way, ATP was found to reduce the lateral displacement of the total population of vesicles by 40%. Because all these perturbations increase [Ca²⁺](i), we speculated that this increase in [Ca²⁺](i) was responsible for the vesicle arrest. Therefore, we tested the effect of the Ca²⁺ ionophore, ionomycin (1 μM), which in the presence of extracellular Ca²⁺ resulted in a considerable and sustained reduction of vesicular movement amounting to a 58% decrease in average lateral vesicular displacement. Our data suggest that vesicles transported on microtubules are paused when subjected to high intracellular Ca²⁺ concentrations. This may provide an additional explanation for the cytotoxic effect of high [Ca²⁺](i).
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Affiliation(s)
- Randi G Bjaelde
- Department of Biomedicine, Aarhus University, Ole Worms Alle 4, Build. 1160, 8000, Aarhus C, Denmark
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Falkowski MA, Thomas DDH, Messenger SW, Martin TF, Groblewski GE. Expression, localization, and functional role for synaptotagmins in pancreatic acinar cells. Am J Physiol Gastrointest Liver Physiol 2011; 301:G306-16. [PMID: 21636530 PMCID: PMC3154608 DOI: 10.1152/ajpgi.00108.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 06/01/2011] [Indexed: 01/31/2023]
Abstract
Secretagogue-induced changes in intracellular Ca(2+) play a pivotal role in secretion in pancreatic acini yet the molecules that respond to Ca(2+) are uncertain. Zymogen granule (ZG) exocytosis is regulated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes. In nerve and endocrine cells, Ca(2+)-stimulated exocytosis is regulated by the SNARE-associated family of proteins termed synaptotagmins. This study examined a potential role for synaptotagmins in acinar secretion. RT-PCR revealed that synaptotagmin isoforms 1, 3, 6, and 7 are present in isolated acini. Immunoblotting and immunofluorescence using three different antibodies demonstrated synaptotagmin 1 immunoreactivity in apical cytoplasm and ZG fractions of acini, where it colocalized with vesicle-associated membrane protein 2. Synaptotagmin 3 immunoreactivity was detected in membrane fractions and colocalized with an endolysosomal marker. A potential functional role for synaptotagmin 1 in secretion was indicated by results that introduction of synaptotagmin 1 C2AB domain into permeabilized acini inhibited Ca(2+)-dependent exocytosis by 35%. In contrast, constructs of synaptotagmin 3 had no effect. Confirmation of these findings was achieved by incubating intact acini with an antibody specific to the intraluminal domain of synaptotagmin 1, which is externalized following exocytosis. Externalized synaptotagmin 1 was detected exclusively along the apical membrane. Treatment with CCK-8 (100 pM, 5 min) enhanced immunoreactivity by fourfold, demonstrating that synaptotagmin is inserted into the apical membrane during ZG fusion. Collectively, these data indicate that acini express synaptotagmin 1 and support that it plays a functional role in secretion whereas synaptotagmin 3 has an alternative role in endolysosomal membrane trafficking.
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Thomas DDH, Frey CL, Messenger SW, August BK, Groblewski GE. A role for tumor protein TPD52 phosphorylation in endo-membrane trafficking during cytokinesis. Biochem Biophys Res Commun 2010; 402:583-7. [PMID: 20946871 DOI: 10.1016/j.bbrc.2010.10.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 10/08/2010] [Indexed: 01/12/2023]
Abstract
Tumor protein D52 is expressed at high levels in exocrine cells containing large secretory granules where it regulates Ca(2+)-dependent protein secretion; however, D52 expression is also highly induced in multiple cancers. The present study investigated a role for the Ca(2+)-dependent phosphorylation of D52 at the single major phospho-acceptor site serine 136 on cell division. Ectopic expression of wild type D52 (D52wt) and the phosphomutants serine 136/alanine (S136A) or serine 136/glutamate (S136/E) resulted in significant multinucleation of cells. D52wt and S136/E each resulted in a greater than 2-fold increase in multinucleated cells compared to plasmid-transfected controls whereas the S136/A phospho-null mutant caused a 9-fold increase in multinucleation at 48h post-transfection. Electron microscopy revealed D52 expression induced a marked accumulation of vesicles along the mid-line between nuclei where the final stages of cell abscission normally occurs. Supporting this, D52wt strongly colocalized on vesicular structures containing the endosomal regulatory protein vesicle associated membrane protein 8 (VAMP 8) and this colocalization significantly increased with elevations in cellular Ca(2+). As VAMP 8 is known to be necessary for the endo-membrane fusion reactions that mediate the final stages of cytokinesis, these data indicate that D52 expression and phosphorylation at serine 136 play an important role in supporting the Ca(2+)-dependent membrane trafficking events necessary for cytokinesis in rapidly proliferating cancer cells.
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Affiliation(s)
- Diana D H Thomas
- University of Wisconsin, Department of Nutritional Sciences, Madison, WI 53706, USA.
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Johnson JN, Ahrendt E, Braun JEA. CSPalpha: the neuroprotective J protein. Biochem Cell Biol 2010; 88:157-65. [PMID: 20453918 DOI: 10.1139/o09-124] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cysteine string protein (CSPalpha, also called DnaJC5) is unique among J proteins. Similar to other J proteins, CSPalpha interacts with and activates the ATPase of Hsc70s (heat shock proteins of 70 kDa), thereby harnessing the ATPase activity for conformational work on client proteins. In contrast to other J proteins, CSPalpha is anchored to synaptic vesicles, as well as to exocrine, endocrine and neuroendocrine secretory granules, and has been shown to have an essential anti-neurodegenerative role. CSPalpha-null organisms exhibit progressive neurodegeneration, behavioural deficits, and premature death, most likely due to the progressive misfolding of one or more client proteins. Here we highlight recent advances in our understanding of the critical role that CSPalpha plays in governing exocytotic secretory functions.
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Affiliation(s)
- Jadah N Johnson
- Department of Physiology and Pharmacology and the Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
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Falkowski MA, Thomas DDH, Groblewski GE. Complexin 2 modulates vesicle-associated membrane protein (VAMP) 2-regulated zymogen granule exocytosis in pancreatic acini. J Biol Chem 2010; 285:35558-66. [PMID: 20829354 DOI: 10.1074/jbc.m110.146597] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Complexins are soluble proteins that regulate the activity of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes necessary for vesicle fusion. Neuronal specific complexin 1 has inhibitory and stimulatory effects on exocytosis by clamping trans-SNARE complexes in a prefusion state and promoting conformational changes to facilitate membrane fusion following cell stimulation. Complexins are unable to bind to monomeric SNARE proteins but bind with high affinity to ternary SNARE complexes and with lower affinity to target SNARE complexes. Far less is understood about complexin function outside the nervous system. Pancreatic acini express the complexin 2 isoform by RT-PCR and immunoblotting. Immunofluorescence microscopy revealed complexin 2 localized along the apical plasma membrane consistent with a role in secretion. Accordingly, complexin 2 was found to interact with vesicle-associated membrane protein (VAMP) 2, syntaxins 3 and 4, but not with VAMP 8 or syntaxin 2. Introduction of recombinant complexin 2 into permeabilized acini inhibited Ca(2+)-stimulated secretion in a concentration-dependent manner with a maximal inhibition of nearly 50%. Mutations of the central α-helical domain reduced complexin 2 SNARE binding and concurrently abolished its inhibitory activity. Surprisingly, mutation of arginine 59 to histidine within the central α-helical domain did not alter SNARE binding and moreover, augmented Ca(2+)-stimulated secretion by 130% of control. Consistent with biochemical studies, complexin 2 colocalized with VAMP 2 along the apical plasma membrane following cholecystokinin-8 stimulation. These data demonstrate a functional role for complexin 2 outside the nervous system and indicate that it participates in the Ca(2+)-sensitive regulatory pathway for zymogen granule exocytosis.
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Affiliation(s)
- Michelle A Falkowski
- Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA
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Abstract
PURPOSE OF REVIEW This review identifies and puts into context the recent articles which have advanced understanding of the functions of pancreatic acinar cells and the mechanisms by which these functions are regulated. RECENT FINDINGS Receptors present on acinar cells, particularly those for cholecystokinin and secretin, have been better characterized as to the molecular nature of the ligand-receptor interaction. Other reports have described the potential regulation of acinar cells by GLP-1 and cannabinoids. Intracellular Ca2+ signaling remains at the center of stimulus secretion coupling and its regulation has been further defined. Recent studies have identified specific channels mediating Ca2+ release from intracellular stores and influx across the plasma membrane. Work downstream of intracellular mediators has focused on molecular mechanisms of exocytosis particularly involving small G proteins, SNARE proteins and chaperone molecules. In addition to secretion, recent studies have further defined the regulation of pancreatic growth both in adaptive regulation to diet and hormones in the regeneration that occurs after pancreatic damage. Lineage tracing has been used to show the contribution of different cell types. The importance of specific amino acids as signaling molecules to activate the mTOR pathway is being elucidated. SUMMARY Understanding the mechanisms that regulate pancreatic acinar cell function is contributing to knowledge of normal pancreatic function and alterations in disease.
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