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Marolt U, Paradiž Leitgeb E, Pohorec V, Lipovšek S, Venglovecz V, Gál E, Ébert A, Menyhárt I, Potrč S, Gosak M, Dolenšek J, Stožer A. Calcium imaging in intact mouse acinar cells in acute pancreas tissue slices. PLoS One 2022; 17:e0268644. [PMID: 35657915 PMCID: PMC9165796 DOI: 10.1371/journal.pone.0268644] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/04/2022] [Indexed: 12/22/2022] Open
Abstract
The physiology and pathophysiology of the exocrine pancreas are in close connection to changes in intra-cellular Ca2+ concentration. Most of our knowledge is based on in vitro experiments on acinar cells or acini enzymatically isolated from their surroundings, which can alter their structure, physiology, and limit our understanding. Due to these limitations, the acute pancreas tissue slice technique was introduced almost two decades ago as a complementary approach to assess the morphology and physiology of both the endocrine and exocrine pancreas in a more conserved in situ setting. In this study, we extend previous work to functional multicellular calcium imaging on acinar cells in tissue slices. The viability and morphological characteristics of acinar cells within the tissue slice were assessed using the LIVE/DEAD assay, transmission electron microscopy, and immunofluorescence imaging. The main aim of our study was to characterize the responses of acinar cells to stimulation with acetylcholine and compare them with responses to cerulein in pancreatic tissue slices, with special emphasis on inter-cellular and inter-acinar heterogeneity and coupling. To this end, calcium imaging was performed employing confocal microscopy during stimulation with a wide range of acetylcholine concentrations and selected concentrations of cerulein. We show that various calcium oscillation parameters depend monotonically on the stimulus concentration and that the activity is rather well synchronized within acini, but not between acini. The acute pancreas tissue slice represents a viable and reliable experimental approach for the evaluation of both intra- and inter-cellular signaling characteristics of acinar cell calcium dynamics. It can be utilized to assess many cells simultaneously with a high spatiotemporal resolution, thus providing an efficient and high-yield platform for future studies of normal acinar cell biology, pathophysiology, and screening pharmacological substances.
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Affiliation(s)
- Urška Marolt
- Clinical department for abdominal and general surgery, University Medical Centre Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Saška Lipovšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Chemistry and Chemical Engineering, University of Maribor, Maribor, Slovenia
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Eleonóra Gál
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Attila Ébert
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - István Menyhárt
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Stojan Potrč
- Clinical department for abdominal and general surgery, University Medical Centre Maribor, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
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Wang L, Wang J, Wang Z, Zhou J, Zhang Y. Higher Urine Exosomal miR-193a Is Associated With a Higher Probability of Primary Focal Segmental Glomerulosclerosis and an Increased Risk of Poor Prognosis Among Children With Nephrotic Syndrome. Front Cell Dev Biol 2021; 9:727370. [PMID: 34708038 PMCID: PMC8542839 DOI: 10.3389/fcell.2021.727370] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 09/22/2021] [Indexed: 12/29/2022] Open
Abstract
Background: In children, focal segmental glomerulosclerosis (FSGS) is one of the most common primary glomerular diseases leading to end-stage renal disease. Exosomes facilitate communication between cells by transporting proteins and microRNAs. We aimed to investigate the utility of urine exosomal miR-193a for diagnosis and prognosis estimation among patients with primary FSGS, and preliminarily explore the regulation mechanism of exosome secretion from podocytes. Methods: Specimens of urine were obtained from patients with primary FSGS, minimal change nephropathy (MCN) and IgA nephropathy (IgAN), followed by exosome isolation. We quantified urine exosomal miR-193a based on quantitative reverse transcription-polymerase chain reaction, and evaluated its applicability using area-under-receiver-operating-characteristics curves (AUROCs). The semiquantitative glomerulosclerosis index (GSI) was used to evaluate the degree of glomerulosclerosis according to the method of Raij et al. We further used FAM-labeled miR-193a-5p to examine exosome shuttling using confocal microscopy for visualization, and explored the regulation mechanism of exosomes release from podocytes using Fluo-3AM dye. Results: Urine exosomal miR-193a levels were significantly higher in patients with primary FSGS than those with MCN and IgAN. The AUROCs for discriminating between primary FSGS and MCN or IgAN were 0.85 and 0.821, respectively. Urine exosomal miR-193a levels positively correlated with GSI in patients with primary FSGS. We further found that kidney tissues from these patients had increased CD63 expression involving podocytes in non-sclerotic tufts. Exosomes from cultured podocytes could transport miR-193a-5p to recipient cells, potentially through a calcium-dependent release mechanism. Conclusion: Urine exosomal miR-193a might be harnessed as a non-invasive marker for diagnosis and outcome assessment among patients with primary FSGS. Exosomes were potential vehicles for miRNAs shuttling between podocytes, and released from podocytes in a calcium-dependent manner.
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Affiliation(s)
- Lixia Wang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Department of Neonatology, Maternal and Child Health Hospital of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jie Wang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhimin Wang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jianhua Zhou
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Zhang
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Abstract
The intestinal production of lipoproteins is one of the key processes by which the body prepares dietary lipid for dissemination to locations throughout the body where they are required. Paramount to this is the relationship between dietary lipid and the enterocytes that line the gut, along with the processes which prepare this lipid for efficient uptake by these cells. These include those which occur in the mouth and stomach along with those which occur within the intestinal lumen itself. Additionally, the interplay between digested lipid, dual avenues for lipid uptake by enterocytes (passive and lipid transporter proteins), a system of intercellular lipid resynthesis and transport, and a complex system of lipoprotein synthesis yield a system open to significant modulation. In this review, we will attempt to outline the processes of lipid digestion, lipoprotein synthesis and the exogenous and endogenous factors which exert their influence.
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Affiliation(s)
- Alan A Hennessy
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland,
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Gómez-Lázaro M, Rinn C, Aroso M, Amado F, Schrader M. Proteomic analysis of zymogen granules. Expert Rev Proteomics 2014; 7:735-47. [DOI: 10.1586/epr.10.31] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Directing exocrine secretory vesicles to the apical membrane by actin cables generated by the formin mDia1. Proc Natl Acad Sci U S A 2013; 110:10652-7. [PMID: 23754409 DOI: 10.1073/pnas.1303796110] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The final stage in exocrine secretion involves translocation of vesicles from their storage areas to the apical membrane. We show that actin-coated secretory vesicles of the exocrine pancreas travel this distance over bundles of specialized actin cables emanating from the apical plasma membrane. These bundles are stable structures that require constant G-actin incorporation and are distinct from the actin web that surrounds the exocrine lumen. The murine mammalian Diaphanous-related formin 1 (mDia1) was identified as a generator of these cables. The active form of mDia1 localized to the apical membrane, and introduction of an active form of mDia1 led to a marked increase in bundle density along the lumen perimeter. Compromising formation of the cables does not prevent secretion, but results in disorganized trafficking and fusion between secretory vesicles. Similar apical secretory tracks were also found in the submandibular salivary glands. Together with previous results that identified a role for Diaphanous in apical secretion in tubular organs of Drosophila, the role of Diaphanous formins at the final stages of secretion appears to be highly conserved.
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Mashima H, Sato T, Horie Y, Nakagawa Y, Kojima I, Ohteki T, Ohnishi H. Interferon regulatory factor-2 regulates exocytosis mechanisms mediated by SNAREs in pancreatic acinar cells. Gastroenterology 2011; 141:1102-1113.e1-8. [PMID: 21699790 DOI: 10.1053/j.gastro.2011.05.051] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 05/16/2011] [Accepted: 05/23/2011] [Indexed: 12/19/2022]
Abstract
BACKGROUND & AIMS Pancreatic acinar cells are used to study regulated exocytosis. We investigated the role of interferon regulatory factor-2 (IRF2) in exocytosis in pancreatic acinar cells. METHODS Pancreas tissues from Irf2⁺/⁺, Irf2⁺/⁻), and Irf2⁻/⁻ mice were examined by microscopy, immunohistochemical, and immunoblot analyses; amylase secretion was quantified. We also compared salivary glands and pancreatic islets of Irf2⁻/⁻ mice with those of Irf2⁺/⁻ mice. To examine the effects of increased signaling by type I interferons, we studied pancreatic acini from Irf2⁻/⁻Ifnar1⁻/⁻ mice. The effect of IRF2 on amylase secretion was studied using an acinar cell line and a retroviral system. We studied expression of IRF2 in wild-type mice with cerulein-induced pancreatitis and changes in pancreatic tissue of Irf2⁻/⁻ mice, compared with those of Irf2⁺/⁻ mice. RESULTS Irf2⁻/⁻ pancreas was white and opaque; numerous and wide-spread zymogen granules were observed throughout the cytoplasm, along with lack of fusion between zymogen granules and the apical membrane, lack of secretagogue-stimulated amylase secretion, and low serum levels of amylase and elastase-1, indicating altered regulation of exocytosis. The expression pattern of soluble N-ethylmaleimide-sensitive factor attachment protein receptors changed significantly, specifically in pancreatic acini, and was not rescued by disruption of type I interferon signaling. Down-regulation of IRF2 decreased amylase secretion in an acinar cell line. In mice with pancreatitis, levels of IRF2 were reduced. Irf2⁻/⁻ acini were partially resistant to induction of pancreatitis. CONCLUSIONS IRF2 regulates exocytosis in pancreatic acinar cells; defects in this process might be involved in the early phases of acute pancreatitis.
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Affiliation(s)
- Hirosato Mashima
- Department of Gastroenterology, Akita University Graduate School of Medicine, Akita, Japan.
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Crystal structures of human secretory proteins ZG16p and ZG16b reveal a Jacalin-related β-prism fold. Biochem Biophys Res Commun 2010; 404:201-5. [PMID: 21110947 DOI: 10.1016/j.bbrc.2010.11.093] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 11/22/2010] [Indexed: 11/24/2022]
Abstract
ZG16p is a secretory protein that mediates condensation-sorting of pancreatic enzymes to the zymogen granule membrane in pancreatic acinar cells. ZG16p interacts with glycosaminoglycans and the binding is considered to be important for condensation-sorting of pancreatic enzymes. ZG16b/PAUF, a paralog of ZG16p, has recently been found to play a role in gene regulation and cancer metastasis. However, the detailed functions of ZG16p and ZG16b remain to be clarified. Here, in order to obtain insights into structure-function relationships, we conducted crystallographic studies of human ZG16p lectin as well as its paralog, ZG16b, and determined their crystal structures at 1.65 and 2.75 Å resolution, respectively. ZG16p has a Jacalin-related β-prism fold, the first to be reported among mammalian lectins. The putative sugar-binding site of ZG16p is occupied by a glycerol molecule, mimicking the mannose bound to Jacalin-related mannose-binding-type plant lectins such as Banlec. ZG16b also has a β-prism fold, but some amino acid residues of the putative sugar-binding site differ from those of the mannose-type binding site suggesting altered preference. A positively charged patch, which may bind sulfated groups of the glycosaminoglycans, is located around the putative sugar-binding site of ZG16p and ZG16b. Taken together, we suggest that the sugar-binding site and the adjacent basic patch of ZG16p and ZG16b cooperatively form a functional glycosaminoglycan-binding site.
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Borta H, Aroso M, Rinn C, Gomez-Lazaro M, Vitorino R, Zeuschner D, Grabenbauer M, Amado F, Schrader M. Analysis of low abundance membrane-associated proteins from rat pancreatic zymogen granules. J Proteome Res 2010; 9:4927-39. [PMID: 20707389 DOI: 10.1021/pr100052q] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Zymogen granules (ZG) are specialized storage organelles in the exocrine pancreas that allow the sorting, packaging, and regulated apical secretion of digestive enzymes. As there is a critical need for further understanding of the key processes in regulated secretion to develop new therapeutic options in medicine, we applied a suborganellar proteomics approach to identify peripheral membrane-associated ZG proteins. We focused on the analysis of a "basic" group (pH range 6.2-11) with about 46 spots among which 44 were identified by tandem mass spectrometry. These spots corresponded to 16 unique proteins, including rat mast cell chymase (RMCP-1) and peptidyl-prolyl cis-trans isomerase B (PpiB; cyclophilin B), an ER-resident protein. To confirm that these proteins were specific to zymogen granules and not contaminants of the preparation, we conducted a series of validation experiments. Immunoblotting of ZG subfractions revealed that chymase and PpiB behaved like bona fide peripheral membrane proteins. Their expression in rat pancreas was regulated by feeding behavior. Ultrastructural and immunofluorescence studies confirmed their ZG localization. Furthermore, a chymase-YFP fusion protein was properly targeted to ZG in pancreatic AR42J cells. Interestingly, for both proteins, proteoglycan-binding properties have been reported. The importance of our findings for sorting and packaging during ZG formation is discussed.
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Affiliation(s)
- Heike Borta
- Department of Cell Biology and Cell Pathology, Philipps University of Marburg, Robert Koch Strasse 6, Marburg, Germany
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MIST1 regulates the pancreatic acinar cell expression of Atp2c2, the gene encoding secretory pathway calcium ATPase 2. Exp Cell Res 2010; 316:2859-70. [PMID: 20599950 DOI: 10.1016/j.yexcr.2010.06.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 05/25/2010] [Accepted: 06/16/2010] [Indexed: 12/11/2022]
Abstract
MIST1 is a transcription factor expressed in pancreatic acinar cells and other serous exocrine cells. Mice harboring a targeted deletion of the Mist1 gene (Mist1(-/-)) exhibit alterations in acinar regulated exocytosis and aberrant Ca(2+) signaling that are normally controlled by acinar cell Ca(2+)-ATPases. Previous studies indicated that total sarcoendoplasmic reticulum Ca(2+)-ATPases (SERCA) and plasma membrane Ca(2+)-ATPases (PMCA) remained unaffected in Mist1(-/-) acinar cultures. Therefore, we have assessed the expression of Atp2c2, the gene that encodes the secretory pathway Ca(2+)-ATPase 2 (SPCA2). We revealed a dramatic decrease in pancreatic expression of Atp2a2 mRNA and SPCA2 protein in Mist1(-/-) mice. Surprisingly, this analysis indicated that the acinar-specific Atp2c2 mRNA is a novel transcript, consisting of only the 3' end of the gene and the protein and localizes to the endoplasmic reticulum. Expression of SPCA2 was also lost in Mist1(-/-) secretory cells of the salivary glands and seminal vesicles, suggesting that Atp2c2 transcription is regulated by MIST1. Indeed, inducible MIST1 expression in Mist1(-/-) pancreatic acinar cells restored normal Atp2c2 expression, supporting a role for MIST1 in regulating the Atp2c2 gene. Based on these results, we have identified a new Atp2c2 transcript, the loss of which may be linked to the Mist1(-/-) phenotype.
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Abstract
The most widely used pharmacological therapies for obesity and weight management are based on inhibition of gastrointestinal lipases, resulting in a reduced energy yield of ingested foods by reducing dietary lipid absorption. Colipase-dependent pancreatic lipase is believed to be the major gastrointestinal enzyme involved in catalysis of lipid ester bonds. There is scant literature on the action of pancreatic lipase under the range of physiological conditions that occur within the human small intestine, and the literature that does exist is often contradictory. Due to the importance of pancreatic lipase activity to nutrition and weight management, the present review aims to assess the current body of knowledge with regards to the physiology behind the action of this unique gastrointestinal enzyme system. Existing data would suggest that pancreatic lipase activity is affected by intestinal pH, the presence of colipase and bile salts, but not by the physiological range of Ca ion concentration (as is commonly assumed). The control of secretion of pancreatic lipase and its associated factors appears to be driven by gastrointestinal luminal content, particularly the presence of acid or digested proteins and fats in the duodenal lumen. Secretion of colipase, bile acids and pancreatic lipase is driven by cholecystokinin and secretin release.
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Fletcher PL, Fletcher MD, Weninger K, Anderson TE, Martin BM. Vesicle-associated membrane protein (VAMP) cleavage by a new metalloprotease from the Brazilian scorpion Tityus serrulatus. J Biol Chem 2009; 285:7405-16. [PMID: 20026600 DOI: 10.1074/jbc.m109.028365] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We present evidence that venom from the Brazilian scorpion Tityus serrulatus and a purified fraction selectively cleave essential SNARE proteins within exocrine pancreatic tissue. Western blotting for vesicle-associated membrane protein type v-SNARE proteins (or synaptobrevins) reveals characteristic alterations to venom-treated excised pancreatic lobules in vitro. Immunocytochemistry by electron microscopy confirms both the SNARE identity as VAMP2 and the proteolysis of VAMP2 as a marked decrease in secondary antibody-conjugated colloidal gold particles that are predominantly associated with mature zymogen granules. Studies with recombinant SNARE proteins were used to determine the specific cleavage site in VAMP2 and the susceptibility of VAMP8 (endobrevin). The VAMP2 cleavage site is between the transmembrane anchor and the SNARE motif that assembles into the ternary SNARE complex. Inclusion of divalent chelating agents (EDTA) with fraction nu, an otherwise active purified component from venom, eliminates SNARE proteolysis, suggesting the active protein is a metalloprotease. The unique cleavages of VAMP2 and VAMP8 may be linked to pancreatitis that develops following scorpion envenomation as both of these v-SNARE proteins are associated with zymogen granule membranes in pancreatic acinar cells. We have isolated antarease, a metalloprotease from fraction nu that cleaves VAMP2, and report its amino acid sequence.
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Affiliation(s)
- Paul L Fletcher
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina 27834, USA
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Schnekenburger J, Weber IA, Hahn D, Buchwalow I, Krüger B, Albrecht E, Domschke W, Lerch MM. The role of kinesin, dynein and microtubules in pancreatic secretion. Cell Mol Life Sci 2009; 66:2525-37. [PMID: 19488676 PMCID: PMC11115865 DOI: 10.1007/s00018-009-0052-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 05/08/2009] [Accepted: 05/13/2009] [Indexed: 10/20/2022]
Abstract
The regulated secretion of pancreatic zymogens depends on a functional cytoskeleton and intracellular vesicle transport. To study the dynamics of tubulin and its motor proteins dynein and kinesin during secretion in pancreatic acinar cells, we infused rats with 0.1 mug/kg/h caerulein. Electron and fluorescence microscopy detected neither dynein nor kinesin at the apical secretory pole, nor on the surface of mature zymogen granules. After 30 min of secretagogue stimulation, kinesin and the Golgi marker protein 58 K were reallocated towards the apical plasma membrane and association of kinesin with tubulin was enhanced. Disruption of acinar cell microtubules had no effect on initial caerulein-induced amylase release but completely blocked secretion during a second stimulus. Our results suggest that mature zymogen granule exocytosis is independent of intact microtubules, kinesin and dynein. However, microtubule-dependent mechanisms seem to be important for the replenishment of secretory vesicles by redistribution of Golgi elements towards the apical cell pole.
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Affiliation(s)
- Jürgen Schnekenburger
- Department of Medicine B, Westfälische Wilhelms-University, Domagkstr. 3A, 48149 Münster, Germany.
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Palandri F, Castagnetti F, Soverini S, Poerio A, Gugliotta G, Luatti S, Amabile M, Martinelli G, Rosti G, Baccarani M. Pancreatic enzyme elevation in chronic myeloid leukemia patients treated with nilotinib after imatinib failure. Haematologica 2009; 94:1758-61. [PMID: 19608673 DOI: 10.3324/haematol.2009.010496] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
An increase in the serum concentration of pancreatic enzymes (amylase and lipase) was reported in a proportion of imatinib-resistant and/or intolerant Philadelphia-positive chronic myeloid leukemia patients treated with nilotinib. Acute pancreatitis was very rare, and the relevance of these laboratory alterations remains unknown. We report on 8 chronic myeloid leukemia patients who developed serum lipase/amylase elevation during treatment with nilotinib. After a median follow-up of 26 months, none of these patients developed an acute pancreatitis or clinical signs of pancreatic disease. Pancreatic hyperenzymemia never led to permanent drug discontinuation and required nilotinib temporary interruption in one case only. The median cumulative duration of dose interruptions and response to treatment were comparable in patients with or without pancreatic enzyme elevation. The mechanisms of action of nilotinib on pancreatic enzymes deserves to be investigated: however, in our experience, the relevance of pancreatic hyperenzymemia was clinically very limited.
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Affiliation(s)
- Francesca Palandri
- Department of Hematology and Medical Oncology L. and A. Seràgnoli, St. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy.
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Weng N, Baumler MD, Thomas DDH, Falkowski MA, Swayne LA, Braun JEA, Groblewski GE. Functional role of J domain of cysteine string protein in Ca2+-dependent secretion from acinar cells. Am J Physiol Gastrointest Liver Physiol 2009; 296:G1030-9. [PMID: 19282376 PMCID: PMC2696211 DOI: 10.1152/ajpgi.90592.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The heat shock protein 70 family members Hsc70 and Hsp70 are known to play a protective role against the onset of experimental pancreatitis, yet their molecular function in acini is unclear. Cysteine string protein (CSP-alpha) is a zymogen granule (ZG) membrane protein characterized by an NH(2)-terminal "J domain" and a central palmitoylated string of cysteine residues. The J domain functions as a cochaperone by modulating the activity of Hsc70/Hsp70 family members. A role for CSP-alpha in regulating digestive enzyme exocytosis from pancreas was investigated by introducing CSP-alpha truncations into isolated acini following their permeabilization with Perfringolysin O. Incubation of acini with CSP-alpha(1-82), containing the J domain, significantly augmented Ca(2+)-stimulated amylase secretion. Effects of CSP-alpha(1-82) were concentration dependent, with a maximum 80% increase occurring at 200 microg/ml of protein. Although CSP-alpha(1-82) had no effects on basal secretion measured in the presence of < or =10 nM free Ca(2+), it did significantly augment GTP-gammaS-induced secretion under basal Ca(2+) conditions by approximately 25%. Mutation of the J domain to abolish its cochaperone activity failed to augment Ca(2+)-stimulated secretion, implicating the CSP-alpha/Hsc70 cochaperone system as a regulatory component of the secretory pathway. CSP-alpha physically associates with vesicle-associated membrane protein 8 (VAMP 8) on ZGs, and the CSP-alpha-VAMP 8 interaction was dependent on amino acids 83-112 of CSP-alpha. Immunofluorescence analysis of acinar lobules or purified ZGs confirmed the CSP-alpha colocalization with VAMP 8. These data establish a role for CSP-alpha in regulating digestive enzyme secretion and suggest that CSP-alpha and Hsc70 modulate specific soluble N-ethylmaleimide-sensitive attachment receptor interactions necessary for exocytosis.
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Affiliation(s)
- Ning Weng
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin; Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Alberta, Canada
| | - Megan D. Baumler
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin; Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Alberta, Canada
| | - Diana D. H. Thomas
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin; Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Alberta, Canada
| | - Michelle A. Falkowski
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin; Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Alberta, Canada
| | - Leigh Anne Swayne
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin; Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Alberta, Canada
| | - Janice E. A. Braun
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin; Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Alberta, Canada
| | - Guy E. Groblewski
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin; Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Alberta, Canada
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Tandler B. Serous cells in the parotid glands of two species of tamarins: polarized secretory granules. Anat Rec (Hoboken) 2008; 291:1254-61. [PMID: 18780306 DOI: 10.1002/ar.20744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The parotid glands of two species of tamarins were examined by electron microscopy. Endpiece cells are typical in appearance, with an extensive rough endoplasmic reticulum, prominent Golgi apparatuses, and numerous serous granules. In the saddleback tamarin, the secretory granules contain a dense spherule pressed against the inner aspect of the limiting membrane, leading to a surface bulge. During the course of merocrine secretion (a form of exocytosis), such morphologically polarized granules approach the luminal plasma membranes with the bulge in the vanguard. It is these protuberances that fuse with the plasmalemma. In contrast, although serous granules in the cotton top tamarin contain a spherule, they lack surface bulges and their docking on luminal membranes seems to be a random event with respect to their surface morphology. Moreover, certain other types of cells in a taxonomically wide spectrum of species have granules with a less obvious structural polarity, as well as cells whose granules lack morphological polarity but have a functional polarity that comes into play during exocytosis of such secretory granules.
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Affiliation(s)
- Bernard Tandler
- Department of Biological Sciences, School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4905, USA.
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Gatehouse HS, Marshall SDG, Simpson RM, Gatehouse LN, Jackson TA, Christeller JT. Serratia entomophila inoculation causes a defect in exocytosis in Costelytra zealandica larvae. INSECT MOLECULAR BIOLOGY 2008; 17:375-385. [PMID: 18651919 DOI: 10.1111/j.1365-2583.2008.00807.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Rapid elimination of midgut luminal proteinase activity and gut clearance are the two major symptoms of amber disease in Costelytra zealandica larvae because of the three-subunit protein toxin complex produced in Serratia entomophila and Serratia proteamaculans. Quantitative PCR analysis of mRNA from the major serine proteinase gene families showed that loss of proteinase activity did not result from transcriptional downregulation. Unexpectedly, protein levels and rates of protein synthesis increased, rather than decreased, in the midgut of diseased insects. Proteomic analysis of midgut tissues showed marked differences between healthy and diseased midguts. Large increases in soluble forms of both actin and tubulin were identified from 2D-gels, together with concurrent decreases in the levels of polymeric actin-associated proteins: actin depolymerizing factor and cyclophilin. These results suggest that the Serratia toxin acts to cause degradation of the cytoskeletal network and prevent secretion of midgut gut digestive proteinases as both the actin cytoskeleton and microtubules are involved in exocytosis. Proteinases synthesized in the diseased midgut must be rapidly degraded because they do not accumulate in an inactive form.
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Affiliation(s)
- H S Gatehouse
- The Horticulture and Food Research Institute, Palmerston North, New Zealand
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18
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Cum hoc ergo propter hoc ("With this, therefore because of this"). Pediatr Crit Care Med 2008; 9:447-9. [PMID: 18496403 DOI: 10.1097/pcc.0b013e318172ebd1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Faust F, Gomez-Lazaro M, Borta H, Agricola B, Schrader M. Rab8 is Involved in Zymogen Granule Formation in Pancreatic Acinar AR42J Cells. Traffic 2008; 9:964-79. [DOI: 10.1111/j.1600-0854.2008.00739.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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20
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Affiliation(s)
- James A McNew
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street MS-140, Houston, Texas 77251-1892, USA.
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21
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Dong Y, Matigian N, Harvey TJ, Samaratunga H, Hooper JD, Clements JA. Tissue-specific promoter utilisation of the kallikrein-related peptidase genes, KLK5 and KLK7, and cellular localisation of the encoded proteins suggest roles in exocrine pancreatic function. Biol Chem 2008; 389:99-109. [DOI: 10.1515/bc.2008.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractTissue kallikrein (kallikrein 1) was first identified in pancreas and is the namesake of the kallikrein-related peptidase (KLK) family. KLK1 and the other 14 members of the human KLK family are encoded by 15 serine protease genes clustered at chromosome 19q13.4. Our Northern blot analysis of 19 normal human tissues for expression ofKLK4toKLK15identified pancreas as a common expression site for the gene cluster spanningKLK5toKLK13, as well as forKLK15which is located adjacent toKLK1. Consistent with previous reports detailing the ability ofKLKgenes to generate organ- and disease-specific transcripts, detailed molecular andin silicoanalyses indicated thatKLK5andKLK7generate transcripts in pancreas variant from those in skin or ovary. Consistently, we identified in the promoters of theseKLKgenes motifs which conform with consensus binding sites for transcription factors conferring pancreatic expression. In addition, immunohistochemical analysis revealed predominant localisation of KLK5 and KLK7 in acinar cells of the exocrine pancreas, suggesting roles for these enzymes in digestion. Our data also support expression patterns derived from gene duplication events in the humanKLKcluster. These findings suggest that, in addition to KLK1, other related KLK enzymes will function in the exocrine pancreas.
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22
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Lam PPL, Hyvärinen K, Kauppi M, Cosen-Binker L, Laitinen S, Keränen S, Gaisano HY, Olkkonen VM. A cytosolic splice variant of Cab45 interacts with Munc18b and impacts on amylase secretion by pancreatic acini. Mol Biol Cell 2007; 18:2473-80. [PMID: 17442889 PMCID: PMC1924827 DOI: 10.1091/mbc.e06-10-0950] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We identified in a yeast two-hybrid screen the EF-hand Ca(2+)-binding protein Cab45 as an interaction partner of Munc18b. Although the full-length Cab45 resides in Golgi lumen, we characterize a cytosolic splice variant, Cab45b, expressed in pancreatic acini. Cab45b is shown to bind (45)Ca(2+), and, of its three EF-hand motifs, EF-hand 2 is demonstrated to be crucial for the ion binding. Cab45b is shown to interact with Munc18b in an in vitro assay, and this interaction is enhanced in the presence of Ca(2+). In this assay, Cab45b also binds the Munc18a isoform in a Ca(2+)-dependent manner. The endogenous Cab45b in rat acini coimmunoprecipitates with Munc18b, syntaxin 2, and syntaxin 3, soluble N-ethylmaleimide-sensitive factor attachment protein receptors with key roles in the Ca(2+)-triggered zymogen secretion. Furthermore, we show that Munc18b bound to syntaxin 3 recruits Cab45b onto the plasma membrane. Importantly, antibodies against Cab45b are shown to inhibit in a specific and dose-dependent manner the Ca(2+)-induced amylase release from streptolysin-O-permeabilized acini. The present study identifies Cab45b as a novel protein factor involved in the exocytosis of zymogens by pancreatic acini.
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Affiliation(s)
- Patrick P L Lam
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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23
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Leung PS, Ip SP. Pancreatic acinar cell: its role in acute pancreatitis. Int J Biochem Cell Biol 2005; 38:1024-30. [PMID: 16423553 DOI: 10.1016/j.biocel.2005.12.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 11/16/2005] [Accepted: 12/01/2005] [Indexed: 01/14/2023]
Abstract
The pancreatic acinar cell is the functional unit of the exocrine pancreas. It synthesizes, stores, and secretes digestive enzymes. Under normal physiological conditions, digestive enzymes are activated only once they have reached the duodenum. Premature activation of these enzymes within pancreatic acinar cells leads to the onset of acute pancreatitis; it is the major clinical disorder associated with pancreatic acinar cells. Although there have been major advances in our understanding of the pathogenesis of this disease in recent years, available treatment options are still limited to traditional nonspecific and palliative interventions. Novel therapeutic strategies have been suggested based on ongoing research in the physiology and pathophysiology of the disease; these include the administration of systemic antibiotics, antioxidants, cytokine antagonists, and more recently, inhibition of the renin-angiotensin system. Notwithstanding this promising development, most of these potential therapies are still in an experimental stage or clinical trial. Further investigation is needed to prove the efficacy of these novel treatment modalities.
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Affiliation(s)
- Po Sing Leung
- Department of Physiology and School of Chinese Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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Lee AH, Chu GC, Iwakoshi NN, Glimcher LH. XBP-1 is required for biogenesis of cellular secretory machinery of exocrine glands. EMBO J 2005; 24:4368-80. [PMID: 16362047 PMCID: PMC1356340 DOI: 10.1038/sj.emboj.7600903] [Citation(s) in RCA: 346] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Accepted: 11/14/2005] [Indexed: 12/12/2022] Open
Abstract
The secretory function of cells relies on the capacity of the endoplasmic reticulum (ER) to fold and modify nascent polypeptides and to synthesize phospholipids for the subsequent trafficking of secretory proteins through the ER-Golgi network. We have previously demonstrated that the transcription factor XBP-1 activates the expression of certain ER chaperone genes and initiates ER biogenesis. Here, we have rescued the embryonic lethality of XBP-1 deficient fetuses by targeting an XBP-1 transgene selectively to hepatocytes (XBP-1-/-;LivXBP1). XBP-1-/-;LivXBP1 mice displayed abnormalities exclusively in secretory organs such as exocrine pancreas and salivary gland that led to early postnatal lethality from impaired production of pancreatic digestive enzymes. The ER was poorly developed in pancreatic and salivary gland acinar cells, accompanied by decreased expression of ER chaperone genes. Marked apoptosis of pancreatic acinar cells was observed during embryogenesis. Thus, the absence of XBP-1 results in an imbalance between the cargo load on the ER and its capacity to handle it, leading to the activation of ER stress-mediated proapoptotic pathways. These data lead us to propose that XBP-1 is both necessary and sufficient for the full biogenesis of the secretory machinery in exocrine cells.
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Affiliation(s)
- Ann-Hwee Lee
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
| | - Gerald C Chu
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Neal N Iwakoshi
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
| | - Laurie H Glimcher
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, 651 Huntington Avenue, Building FXB, Room 205, Boston, MA 02115, USA. Tel.: +1 617 432 0622; Fax: +1 617 432 0084; E-mail:
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Dahan S, Anderson KL, Weller S, Krueger E, McNiven MA. Agonist-induced vesiculation of the Golgi apparatus in pancreatic acinar cells. Gastroenterology 2005; 129:2032-46. [PMID: 16344069 DOI: 10.1053/j.gastro.2005.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2002] [Accepted: 08/31/2005] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS The pancreatic acinar cell is known to regulate exocytosis, total protein synthesis, and secretory protein transport in response to a secretory stimulus. Whether secretory vesicle formation also is regulated is unclear. In this study, we determined whether agonist stimulation induces morphologic alterations in the acinar cell Golgi apparatus, and we evaluated the role of the vesicle severing protein dynamin. METHODS Changes in Golgi structural integrity by examining the distribution of various Golgi and TGN lipid and protein markers in live and fixed cells on stimulation with cholecystokinin were noted in a primary pancreatic acinar cell model. Multiple dynamin reagents were used to examine the distribution and function of this molecular pinchase in resting and stimulated cells. RESULTS Regulated secretion in acinar cells induced (1) marked fragmentation of the trans-Golgi network (TGN) that corresponded temporally with an increase in cytoplasmic calcium whereas pre-TGN compartments of the Golgi and regions of the TGN involved in the generation of constitutively trafficking vesicles were unaffected by agonist, and (2) significant recruitment of dynamin to the acinar cell Golgi apparatus that appeared to potentiate fragmentation of the TGN. CONCLUSIONS These results suggest that the TGN is a dynamic organelle that fragments in response to cholecystokinin stimulation, a process that may contribute to zymogen granule formation.
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Affiliation(s)
- Sophie Dahan
- Center for Basic Research in Digestive Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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26
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Abstract
Stimulus-secretion coupling is an essential process in secretory cells in which regulated exocytosis occurs, including neuronal, neuroendocrine, endocrine, and exocrine cells. While an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) is the principal signal, other intracellular signals also are important in regulated exocytosis. In particular, the cAMP signaling system is well known to regulate and modulate exocytosis in a variety of secretory cells. Until recently, it was generally thought that the effects of cAMP in regulated exocytosis are mediated by activation of cAMP-dependent protein kinase (PKA), a major cAMP target, followed by phosphorylation of the relevant proteins. Although the involvement of PKA-independent mechanisms has been suggested in cAMP-regulated exocytosis by pharmacological approaches, the molecular mechanisms are unknown. Newly discovered cAMP-GEF/Epac, which belongs to the cAMP-binding protein family, exhibits guanine nucleotide exchange factor activities and exerts diverse effects on cellular functions including hormone/transmitter secretion, cell adhesion, and intracellular Ca(2+) mobilization. cAMP-GEF/Epac mediates the PKA-independent effects on cAMP-regulated exocytosis. Thus cAMP regulates and modulates exocytosis by coordinating both PKA-dependent and PKA-independent mechanisms. Localization of cAMP within intracellular compartments (cAMP compartmentation or compartmentalization) may be a key mechanism underlying the distinct effects of cAMP in different domains of the cell.
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Affiliation(s)
- Susumu Seino
- Division of Cellular and Molecular Medicine, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
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27
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Lee M, Chung S, Uhm DY, Park MK. Regulation of zymogen granule exocytosis by Ca2+, cAMP, and PKC in pancreatic acinar cells. Biochem Biophys Res Commun 2005; 334:1241-7. [PMID: 16040001 DOI: 10.1016/j.bbrc.2005.07.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 07/01/2005] [Indexed: 11/18/2022]
Abstract
The effect of cAMP and PKC on zymogen granule exocytosis was investigated by simultaneously measuring cytosolic Ca2+ concentration ([Ca2+]c) and individual zymogen granule exocytosis in isolated mouse pancreatic acini. When acinar cells were stimulated with acetylcholine (ACh, 10 microM), exocytic events were detected through granule-attached apical membranes with [Ca2+]c rise. Application of secretin, forskolin (an adenylate cyclase activator), or PMA (a PKC activator) alone did not elicit any [Ca2+]c rise or zymogen granule exocytosis, but co-stimulation with ACh led to exocytosis in that the total number of secreted granules increased markedly without a significant difference in [Ca2+]c rises. When we evoked exocytosis by [Ca2+]c ramps, pretreatment with forskolin or PMA elicited exocytosis at lower [Ca2+]c levels. These results indicate that PKC or cAMP alone could not directly elicit zymogen granule exocytosis, but that they increase the total releasable pool by rendering zymogen granules more sensitive to Ca2+.
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Affiliation(s)
- Misun Lee
- Department of Physiology, Center for Molecular Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, 300 Chunchun-dong Jangan-ku, Suwon 440-746, Republic of Korea
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Chen Y, Warner JD, Yule DI, Giovannucci DR. Spatiotemporal analysis of exocytosis in mouse parotid acinar cells. Am J Physiol Cell Physiol 2005; 289:C1209-19. [PMID: 16000640 DOI: 10.1152/ajpcell.00159.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exocrine cells of the digestive system are specialized to secrete protein and fluid in response to neuronal and/or hormonal input. Although morphologically similar, parotid and pancreatic acinar cells exhibit important functional divergence in Ca(2+) signaling properties. To address whether there are fundamental differences in exocytotic release of digestive enzyme from exocrine cells of salivary gland versus pancreas, we applied electrophysiological and optical methods to investigate spatial and temporal characteristics of zymogen-containing secretory granule fusion at the single-acinar cell level by direct or agonist-induced Ca(2+) and cAMP elevation. Temporally resolved membrane capacitance measurements revealed that two apparent phases of exocytosis were induced by Ca(2+) elevation: a rapidly activated initial phase that could not be resolved as individual fusion events and a second phase that was activated after a delay, increased in a staircaselike fashion, was augmented by cAMP elevation, and likely reflected both sequential compound and multivesicular fusion of zymogen-containing granules. Optical measurements of exocytosis with time-differential imaging analysis revealed that zymogen granule fusion was induced after a minimum delay of approximately 200 ms, occurred initially at apical and basolateral borders of acinar cells, and under strong stimulation proceeded from apical pole to deeper regions of the cell interior. Zymogen granule fusions appeared to coordinate subsequent fusions and produced persistent structures that generally lasted several minutes. In addition, parotid gland slices were used to assess secretory dynamics in a more physiological context. Parotid acinar cells were shown to exhibit both similar and divergent properties compared with the better-studied pancreatic acinar cell regarding spatial organization and kinetics of exocytotic fusion of zymogen granules.
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Affiliation(s)
- Ying Chen
- Department of Neurosciences, Medical College of Ohio, Toledo, OH 43614, USA
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29
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Abstract
We use a mathematical model of calcium dynamics in pancreatic acinar cells to investigate calcium oscillations in a ring of three coupled cells. A connected group of cells is modeled in two different ways: 1), as coupled point oscillators, each oscillator being described by a spatially homogeneous model; and 2), as spatially distributed cells coupled along their common boundaries by gap-junctional diffusion of inositol trisphosphate and/or calcium. We show that, although the point-oscillator model gives a reasonably accurate general picture, the behavior of the spatially distributed cells cannot always be predicted from the simpler analysis; spatially distributed diffusion and cell geometry both play important roles in determining behavior. In particular, oscillations in which two cells are in synchrony, with the third phase-locked but not synchronous, appears to be more dominant in the spatially distributed model than in the point-oscillator model. In both types of model, intercellular coupling leads to a variety of synchronous, phase-locked, or asynchronous behaviors. For some parameter values there are multiple, simultaneous stable types of oscillation. We predict 1), that intercellular calcium diffusion is necessary and sufficient to coordinate the responses in neighboring cells; 2), that the function of intercellular inositol trisphosphate diffusion is to smooth out any concentration differences between the cells, thus making it easier for the diffusion of calcium to synchronize the oscillations; 3), that groups of coupled cells will tend to respond in a clumped manner, with groups of synchronized cells, rather than with regular phase-locked periodic intercellular waves; and 4), that enzyme secretion is maximized by the presence of a pacemaker cell in each cluster which drives the other cells at a frequency greater than their intrinsic frequency.
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Johnson CL, Kowalik AS, Rajakumar N, Pin CL. Mist1 is necessary for the establishment of granule organization in serous exocrine cells of the gastrointestinal tract. Mech Dev 2004; 121:261-72. [PMID: 15003629 DOI: 10.1016/j.mod.2004.01.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Revised: 01/07/2004] [Accepted: 01/11/2004] [Indexed: 12/17/2022]
Abstract
Establishing a pool of granules at the luminal border is a key step during exocrine cell development in the pancreas and is necessary for efficient release of digestive enzymes through regulated exocytosis. Several proteins have been linked to maintaining granule organization, but it is unclear which regulatory mechanisms are necessary to establish organization. Based on temporal and spatial expression, the transcription factor Mist1 is an excellent candidate, and analysis of mice that do not express Mist1 (Mist1KO) reveal disrupted cell morphology in adult pancreatic acini. To address Mist1's role in establishing granule location, we have characterized the organization of pancreatic acini throughout development in Mist1KO mice. Using various histological approaches, we have determined that correct granule organization is never established in pancreatic acini of Mist1KO mice. Further examination indicates that this disruption in granule targeting may be the primary defect in Mist1KO mice as granule organization is affected in other serous exocrine cells that normally express Mist1. To identify a mechanistic link between granule targeting and the loss of Mist1 function, intercellular junctions and the expression of Rab3D were assessed. While both of these factors are affected in Mist1KO mice, these changes alone do not account for the disorganization observed in Mist1KO tissues. Therefore, we conclude that Mist1 is necessary for complete differentiation and maturation of serous exocrine cells through the combined regulation of several exocrine specific genes.
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Affiliation(s)
- Charis L Johnson
- Department of Physiology and Pharmacology, University of Western Ontario, Child Health Research Institute, London, Ont., Canada N6C 2V5
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31
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Kampa M, Papakonstanti EA, Alexaki VI, Hatzoglou A, Stournaras C, Castanas E. The opioid agonist ethylketocyclazocine reverts the rapid, non-genomic effects of membrane testosterone receptors in the human prostate LNCaP cell line. Exp Cell Res 2004; 294:434-45. [PMID: 15023532 DOI: 10.1016/j.yexcr.2003.11.027] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 11/24/2003] [Indexed: 11/21/2022]
Abstract
Neuropeptides influence cancer cell replication and growth. Opioid peptides, and opiergic neurons are found in the prostate gland, and they are proposed to exert a role in tumor regulation, influencing cancer cell growth, as opioid agonists inhibit cell growth in several systems, including the human prostate cancer cell line LNCaP. In the same cell line, the existence of membrane testosterone receptors was recently reported, which increase, in a non-genomic manner, the secretion of PSA, and modify actin cytoskeleton dynamics, through the signaling cascade FAK-->PI-3 kinase-->Cdc42/Rac1. In the present work, we present data supporting that the general opioid agonist Ethylketocyclazocine (EKC) decreases testosterone-BSA (a non-internalizable testosterone analog) induced PSA secretion. Furthermore, we report that this opioid affects this non-genomic testosterone action, by modifying the distribution of the actin cytoskeleton in the cells, disrupting the above signaling cascade. In addition, after long (>24 h) incubation, opioids decrease the number of membrane testosterone receptors, and reverse their effect on the signaling molecules. In conclusion, our results provide some new insights of a possible action of opioids in prostate cancer control by interfering with the action and the expression of membrane testosterone receptors and signaling.
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Affiliation(s)
- Marilena Kampa
- Laboratory of Experimental Endocrinology, University of Crete, School of Medicine, 71110, Heraklion, Greece
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Park MK, Lee M, Petersen OH. Morphological and functional changes of dissociated single pancreatic acinar cells: testing the suitability of the single cell as a model for exocytosis and calcium signaling. Cell Calcium 2004; 35:367-79. [PMID: 15036953 DOI: 10.1016/j.ceca.2003.10.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2003] [Revised: 10/12/2003] [Accepted: 10/16/2003] [Indexed: 11/23/2022]
Abstract
Isolated single pancreatic acinar cells have long been used as a model for studying many kinds of signaling processes due to their structural and functional polarities, but without significant validation. In this study, we examined the morphological and functional changes of dissociated single pancreatic acinar cells. Acutely isolated single cells showed a collapsed membrane potential and a much reduced secretion of zymogen granules in response to acetylcholine (ACh) stimulation, whereas clustered cells showed a much more negative membrane potential and potent exocytotic secretion. The isolated single cells became vertically flattened due to the loss of supporting adhesions with nearby cells, and the granule-attached luminal membrane was severely reduced versus that of clustered cells. However, polarized Ca(2+) signals and mitochondrial localizations were relatively well preserved in the isolated single cells, in that Ca(2+) release by ACh commenced at the indented luminal membrane. In clusters, the Ca(2+) release site was closest to the lumen where more than three cells met or at the tips of conical regions of the luminal membrane. These findings suggest that the dissociated single pancreatic acinar cells preserve an intact Ca(2+) signaling machinery but alter in shape and have impaired exocytotic functions and resting membrane potentials.
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Affiliation(s)
- Myoung Kyu Park
- Medical Research Center for Regulation of Neuronal Cell Excitability and Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Jangan-ku, Suwon, 440-746, South Korea.
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Rukstalis JM, Kowalik A, Zhu L, Lidington D, Pin CL, Konieczny SF. Exocrine specific expression of Connexin32 is dependent on the basic helix-loop-helix transcription factor Mist1. J Cell Sci 2003; 116:3315-25. [PMID: 12829745 DOI: 10.1242/jcs.00631] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gap junctions are intercellular channels that provide direct passage of small molecules between adjacent cells. In pancreatic acini, the connexin26 (Cx26) and connexin32 (Cx32) proteins form functional channels that coordinate the secretion of digestive enzymes. Although the function of Cx26/Cx32 gap junctions are well characterized, the regulatory circuits that control the spatial and temporal expression patterns of these connexin genes are not known. In an effort to identify the molecular pathways that regulate connexin gene expression, we examined Cx26 and Cx32 gene activities in mice lacking the basic helix-loop-helix transcription factor Mist1 (Mist1KO). Mist1, Cx26 and Cx32 are co-expressed in most exocrine cell types, and acinar cells from Mist1KO mice exhibit a highly disorganized cellular architecture and an altered pattern of expression for several genes involved in regulated exocytosis. Analysis of Mist1KO mice revealed a dramatic decrease in both connexin proteins, albeit through different molecular mechanisms. Cx32 gene transcription was greatly reduced in all Mist1KO exocrine cells, while Cx26 gene expression remained unaffected. However, in the absence of Cx32 protein, Cx26 did not participate in gap junction formation, leading to a complete lack of intercellular communication among Mist1KO acinar cells. Additional studies testing Mist1 gene constructs in pancreatic exocrine cells confirmed that Mist1 transcriptionally regulates expression of the Cx32 gene. We conclude that Mist1 functions as a positive regulator of Cx32 gene expression and, in its absence, acinar cell gap junctions and intercellular communication pathways become disrupted.
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Affiliation(s)
- J Michael Rukstalis
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA
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Seo SR, Kim YJ, Moon SJ, Sugiya H, Shin DM, Lee SI, Seo JT. Staurosporine-inhibitable protein kinase activity associated with secretory granule membranes isolated from rat submandibular gland cells. Arch Oral Biol 2003; 48:553-8. [PMID: 12828983 DOI: 10.1016/s0003-9969(03)00097-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Protein kinases, such as protein kinase C, have been shown to be associated with secretory granules and to regulate the event of exocytosis in various tissues including parotid salivary acinar cells. However, in submandibular acinar cells that play an important role in the secretion of proteins into the oral cavity, kinase activity on the granule membrane has not been explored. Therefore, in the present study, we isolated the secretory granules from rat submandibular acinar cells and investigated the localisation of protein kinases on the granule membrane. Initially, we isolated and purified secretory granules from rat submandibular acinar cells. Addition of [gamma-32P] ATP to granule-membrane lysate phosphorylated the granule-membrane-associated 26, 32, 55 and 58kDa proteins, suggesting the presence of endogenous kinase activity on the membrane. Moreover, the phosphorylation of 26 and 32kDa proteins was inhibited by staurosporine and K252a, both non-specific protein kinase C inhibitors. However, the phosphorylation of 26 and 32kDa proteins was not inhibited by other protein kinase C inhibitors, such as calphostin C, GF109203X and chelerythrine, indicating that protein kinase C was not responsible for the phosphorylation. In addition, H-89, ML-9, KN-62 and genistein did not appear to inhibit this phosphorylation, indicating that protein kinase A, myosin light chain kinase (MLCK), Ca2+/calmodulin-dependent protein kinase II (CAMKII) and tyrosine kinase were not involved in the phosphorylation of 26 and 32kDa proteins. Moreover, Ca2+ had no effect on the kinase activity. Therefore, our results suggest that an unidentified, staurosporine-inhibitable protein kinase activity is associated with the secretory granule membrane of rat submandibular acinar cells.
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Affiliation(s)
- Su Ryeon Seo
- Department of Oral Biology & Oral Science Research Centre, BK21 Project for Medical Sciences, Yonsei University College of Dentistry, Seoul, South Korea
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Savina A, Furlán M, Vidal M, Colombo MI. Exosome release is regulated by a calcium-dependent mechanism in K562 cells. J Biol Chem 2003; 278:20083-90. [PMID: 12639953 DOI: 10.1074/jbc.m301642200] [Citation(s) in RCA: 603] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Multivesicular bodies (MVBs) are endocytic structures that contain small vesicles formed by the budding of an endosomal membrane into the lumen of the compartment. Fusion of MVBs with the plasma membrane results in secretion of the small internal vesicles termed exosomes. K562 cells are a hematopoietic cell line that releases exosomes. The application of monensin (MON) generated large MVBs that were labeled with a fluorescent lipid. Exosome release was markedly enhanced by MON treatment, a Na+/H+ exchanger that induces changes in intracellular calcium (Ca2+). To explore the possibility that the effect of MON on exosome release was caused via an increase in Ca2+, we have used a calcium ionophore and a chelator of intracellular Ca2+. Our results indicate that increasing intracellular Ca2+ stimulates exosome secretion. Furthermore, MON-stimulated exosome release was completely eliminated by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM), implying a requirement for Ca2+ in this process. We have observed that the large MVBs generated in the presence of MON accumulated Ca2+ as determined by labeling with Fluo3-AM, suggesting that intralumenal Ca2+ might play a critical role in the secretory process. Interestingly, our results indicate that transferrin (Tf) stimulated exosome release in a Ca2+-dependent manner, suggesting that Tf might be a physiological stimulus for exosome release in K562 cells.
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Affiliation(s)
- Ariel Savina
- Laboratorio de Biología Celular y Molecular-Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 5500 Mendoza, Argentina
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Abstract
Regulated exocytosis of secretory granules or dense-core granules has been examined in many well-characterized cell types including neurons, neuroendocrine, endocrine, exocrine, and hemopoietic cells and also in other less well-studied cell types. Secretory granule exocytosis occurs through mechanisms with many aspects in common with synaptic vesicle exocytosis and most likely uses the same basic protein components. Despite the widespread expression and conservation of a core exocytotic machinery, many variations occur in the control of secretory granule exocytosis that are related to the specialized physiological role of particular cell types. In this review we describe the wide range of cell types in which regulated secretory granule exocytosis occurs and assess the evidence for the expression of the conserved fusion machinery in these cells. The signals that trigger and regulate exocytosis are reviewed. Aspects of the control of exocytosis that are specific for secretory granules compared with synaptic vesicles or for particular cell types are described and compared to define the range of accessory control mechanisms that exert their effects on the core exocytotic machinery.
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Affiliation(s)
- Robert D Burgoyne
- The Physiological Laboratory, University of Liverpool, United Kingdom.
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Hodges RR, Dartt DA. Regulatory pathways in lacrimal gland epithelium. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 231:129-96. [PMID: 14713005 DOI: 10.1016/s0074-7696(03)31004-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tears are a complex fluid that continuously cover the exposed surface of the eye, namely the cornea and conjunctiva. Tears are secreted in response to the multitude of environmental stresses that can harm the ocular surface such as cold, mechanical stimulation, physical injury, noxious chemicals, as well as infections from various organisms. Tears also provide nutrients and remove waste from cells of the ocular surface. Because of the varied function of tears, tears are complex and are secreted by several different tissues. Tear secretion is under tight neural control allowing tears to respond rapidly to changing environmental conditions. The lacrimal gland is the main contributor to the aqueous portion of the tear film and the regulation of secretion from this gland has been well studied. Despite multiple redundencies in pathways to stimulate secretion from the lacrimal gland, defects can occur resulting in dry eye syndromes. These diseases can have deleterious effects on vision. In this review, we summarize the latest information regarding the regulatory pathways, which control secretion from the lacrimal gland, and their roles in the pathogenesis of dry eye syndromes.
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Affiliation(s)
- Robin R Hodges
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA
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Bray C, Son JH, Meizel S. A nicotinic acetylcholine receptor is involved in the arosome reaction of human sperm initiated by recombinant human ZP3. Biol Reprod 2002; 67:782-8. [PMID: 12193385 DOI: 10.1095/biolreprod.102.004580] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
One of the essential steps in mammalian fertilization is the acrosome reaction (AR), a modified exocytotic event in the sperm head that occurs upon contact with the glycoprotein matrix of the zona pellucida (ZP) surrounding the oocyte. Acetylcholine (ACh) at concentrations of 10-250 micro M and nicotine at 10-250 nM significantly initiate the AR of capacitated human sperm. Preincubation with three antagonists of the nicotinic acetylcholine receptor (nAChR), alpha-bungarotoxin (alpha-BTX, 100 nM), alpha-conotoxin IMI (alpha-CTX IMI, 250 nM and 25 nM), and methyllycaconitine (MLA, 100 nM and 10 nM), significantly blocked AR initiation by ACh. alpha-BTX is an anatagonist of several nAChRs, including the alpha7 nAChR, and alpha-CTX IMI and MLA are highly specific antagonists of alpha7 subunit-containing AChRs. The sperm nAChR plays a role in the AR initiated in vitro by a purified recombinant human ZP protein (rhZP3). Previously, rhZP3 was able to stimulate the AR by mechanisms similar to those seen with native ZP. Preincubation of human sperm with alpha-BTX (from 10 micro M to 100 nM), alpha-CTX IMI (250 and 100 nM), or MLA (100 nM and 10 nM) caused a significant inhibition in the rhZP3-initated AR. The inhibition of the ACh-initiated and rhZP3-initiated AR by these nAChR antagonists strongly suggests the involvement of an alpha7 subunit-containing nAChR in the AR initiated by both ligands. AR initiation by progesterone was not inhibited by MLA or alpha-BTX, suggesting that this particularnAChR is not involved in the AR initiated by that ligand. In vitro results show for the first time that ACh can initiate the human sperm AR and strongly suggest that a human sperm alpha7 subunit-containing nAChR plays a role in the rhZP3-initiated AR. This nAChR ligand-gated ion channel may be important to the signal transduction events of ZP-initiated AR in vivo.
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Affiliation(s)
- Christopher Bray
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California,Davis, California 95616-8643, USA
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Shvartsman SY. Shooting from the hip: spatial control of signal release by intracellular waves. Proc Natl Acad Sci U S A 2002; 99:9087-9. [PMID: 12093926 PMCID: PMC123095 DOI: 10.1073/pnas.152321799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Stanislav Y Shvartsman
- Department of Chemical Engineering and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
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