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Ouchi T, Kono K, Satou R, Kurashima R, Yamaguchi K, Kimura M, Shibukawa Y. Upregulation of Amy1 in the salivary glands of mice exposed to a lunar gravity environment using the multiple artificial gravity research system. Front Physiol 2024; 15:1417719. [PMID: 38989048 PMCID: PMC11233762 DOI: 10.3389/fphys.2024.1417719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 06/04/2024] [Indexed: 07/12/2024] Open
Abstract
Introduction: Space is a unique environment characterized by isolation from community life and exposure to circadian misalignment, microgravity, and space radiation. These multiple differences from those experienced on the earth may cause systemic and local tissue stress. Autonomic nerves, including sympathetic and parasympathetic nerves, regulate functions in multiple organs. Saliva is secreted from the salivary gland, which is regulated by autonomic nerves, and plays several important roles in the oral cavity and digestive processes. The balance of the autonomic nervous system in the seromucous glands, such as the submandibular glands, precisely controls serous and mucous saliva. Psychological stress, radiation damage, and other triggers can cause an imbalance in salivary secretion systems. A previous study reported that amylase is a stress marker in behavioral medicine and space flight crews; however, the detailed mechanisms underlying amylase regulation in the space environment are still unknown. Methods: In this study, we aimed to elucidate how lunar gravity (1/6 g) changes mRNA expression patterns in the salivary gland. Using a multiple artificial gravity research system during space flight in the International Space Station, we studied the effects of two different gravitational levels, lunar and Earth gravity, on the submandibular glands of mice. All mice survived, returned to Earth from space, and their submandibular glands were collected 2 days after landing. Results: We found that lunar gravity induced the expression of the salivary amylase gene Amy1; however, no increase in Aqp5 and Ano1, which regulate water secretion, was observed. In addition, genes involved in the exocrine system, such as vesicle-associated membrane protein 8 (Vamp8) and small G proteins, including Rap1 and Rab families, were upregulated under lunar gravity. Conclusion: These results imply that lunar gravity upregulates salivary amylase secretion via Rap/Rab signaling and exocytosis via Vamp8. Our study highlights Amy1 as a potential candidate marker for stress regulation in salivary glands in the lunar gravity environment.
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Affiliation(s)
- Takehito Ouchi
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Kyosuke Kono
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Ryouichi Satou
- Department of Epidemiology and Public Health, Tokyo Dental College, Tokyo, Japan
| | - Ryuya Kurashima
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Koji Yamaguchi
- NeSTRA (Next-Generation Space System Technology Research Association), Yokohama, Japan
| | - Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
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Ferri G, Musikant D, Edreira MM. Host Cell Rap1b mediates cAMP-dependent invasion by Trypanosoma cruzi. PLoS Negl Trop Dis 2023; 17:e0011191. [PMID: 36897926 PMCID: PMC10032529 DOI: 10.1371/journal.pntd.0011191] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 03/22/2023] [Accepted: 02/22/2023] [Indexed: 03/11/2023] Open
Abstract
Trypanosoma cruzi cAMP-mediated invasion has long been described, however, the detailed mechanism of action of the pathway activated by this cyclic nucleotide still remains unknown. We have recently demonstrated a crucial role for Epac in the cAMP-mediated invasion of the host cell. In this work, we gathered evidence indicating that the cAMP/Epac pathway is activated in different cells lines. In accordance, data collected from pull-down experiments designed to identify only the active form of Rap1b (Rap1b-GTP), and infection assays using cells transfected with a constitutively active mutant of Rap1b (Rap1b-G12V), strongly suggest the participation of Rap1b as mediator of the pathway. In addition to the activation of this small GTPase, fluorescence microscopy allowed us to demonstrate the relocalization of Rap1b to the entry site of the parasite. Moreover, phospho-mimetic and non-phosphorylable mutants of Rap1b were used to demonstrate a PKA-dependent antagonistic effect on the pathway, by phosphorylation of Rap1b, and potentially of Epac. Finally, Western Blot analysis was used to determine the involvement of the MEK/ERK signalling downstream of cAMP/Epac/Rap1b-mediated invasion.
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Affiliation(s)
- Gabriel Ferri
- CONICET-Universidad de Buenos Aires, IQUIBICEN, Ciudad de Buenos Aires, Argentina
- Laboratorio de Biología Molecular de Trypanosomas, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos, Ciudad de Buenos Aires, Argentina
| | - Daniel Musikant
- CONICET-Universidad de Buenos Aires, IQUIBICEN, Ciudad de Buenos Aires, Argentina
- Laboratorio de Biología Molecular de Trypanosomas, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos, Ciudad de Buenos Aires, Argentina
| | - Martin M Edreira
- CONICET-Universidad de Buenos Aires, IQUIBICEN, Ciudad de Buenos Aires, Argentina
- Laboratorio de Biología Molecular de Trypanosomas, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos, Ciudad de Buenos Aires, Argentina
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Proteomic and Bioinformatic Analysis of Decellularized Pancreatic Extracellular Matrices. Molecules 2021; 26:molecules26216740. [PMID: 34771149 PMCID: PMC8588251 DOI: 10.3390/molecules26216740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 11/04/2021] [Accepted: 11/06/2021] [Indexed: 01/15/2023] Open
Abstract
Tissue microenvironments are rich in signaling molecules. However, factors in the tissue matrix that can serve as tissue-specific cues for engineering pancreatic tissues have not been thoroughly identified. In this study, we performed a comprehensive proteomic analysis of porcine decellularized pancreatic extracellular matrix (dpECM). By profiling dpECM collected from subjects of different ages and genders, we showed that the detergent-free decellularization method developed in this study permits the preservation of approximately 62.4% more proteins than a detergent-based method. In addition, we demonstrated that dpECM prepared from young pigs contained approximately 68.5% more extracellular matrix proteins than those prepared from adult pigs. Furthermore, we categorized dpECM proteins by biological process, molecular function, and cellular component through gene ontology analysis. Our study results also suggested that the protein composition of dpECM is significantly different between male and female animals while a KEGG enrichment pathway analysis revealed that dpECM protein profiling varies significantly depending on age. This study provides the proteome of pancreatic decellularized ECM in different animal ages and genders, which will help identify the bioactive molecules that are pivotal in creating tissue-specific cues for engineering tissues in vitro.
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Williams JA, Groblewski GE, Gorelick FS, Mayerle J, Apte M, Gukovskaya A. American Pancreatic Association Frank Brooks Symposium: Fifty Years of Pancreatic Cell Biology. Pancreas 2021; 49:604-611. [PMID: 32433396 PMCID: PMC7249997 DOI: 10.1097/mpa.0000000000001543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
- John A. Williams
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI
- Department of Internal Medicine (Gastroenterology), University of Michigan, Ann Arbor, MI
| | - Guy E. Groblewski
- Department of Nutritional Sciences, University of Wisconsin, Madison, WI
| | - Fred S. Gorelick
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Julia Mayerle
- Department of Medicine II, Liver Centre Munich, University Hospital, LMU Munich, Germany
| | - Minoti Apte
- Pancreatic Research Group, South Western Sydney Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, Australia
| | - Anna Gukovskaya
- Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, and, VA Greater Los Angeles Healthcare System, Los Angeles, CA
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5
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Ferri G, Edreira MM. All Roads Lead to Cytosol: Trypanosoma cruzi Multi-Strategic Approach to Invasion. Front Cell Infect Microbiol 2021; 11:634793. [PMID: 33747982 PMCID: PMC7973469 DOI: 10.3389/fcimb.2021.634793] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 01/27/2021] [Indexed: 12/17/2022] Open
Abstract
T. cruzi has a complex life cycle involving four developmental stages namely, epimastigotes, metacyclic trypomastigotes, amastigotes and bloodstream trypomastigotes. Although trypomastigotes are the infective forms, extracellular amastigotes have also shown the ability to invade host cells. Both stages can invade a broad spectrum of host tissues, in fact, almost any nucleated cell can be the target of infection. To add complexity, the parasite presents high genetic variability with differential characteristics such as infectivity. In this review, we address the several strategies T. cruzi has developed to subvert the host cell signaling machinery in order to gain access to the host cell cytoplasm. Special attention is made to the numerous parasite/host protein interactions and to the set of signaling cascades activated during the formation of a parasite-containing vesicle, the parasitophorous vacuole, from which the parasite escapes to the cytosol, where differentiation and replication take place.
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Affiliation(s)
- Gabriel Ferri
- CONICET-Universidad de Buenos Aires, IQUIBICEN, Ciudad de Buenos Aires, Argentina
| | - Martin M Edreira
- CONICET-Universidad de Buenos Aires, IQUIBICEN, Ciudad de Buenos Aires, Argentina.,Laboratorio de Biología Molecular de Trypanosoma, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos, Ciudad de Buenos Aires, Argentina.,Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
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Kurashima Y, Kigoshi T, Murasaki S, Arai F, Shimada K, Seki N, Kim YG, Hase K, Ohno H, Kawano K, Ashida H, Suzuki T, Morimoto M, Saito Y, Sasou A, Goda Y, Yuki Y, Inagaki Y, Iijima H, Suda W, Hattori M, Kiyono H. Pancreatic glycoprotein 2 is a first line of defense for mucosal protection in intestinal inflammation. Nat Commun 2021; 12:1067. [PMID: 33594081 PMCID: PMC7887276 DOI: 10.1038/s41467-021-21277-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 01/15/2021] [Indexed: 02/06/2023] Open
Abstract
Increases in adhesive and invasive commensal bacteria, such as Escherichia coli, and subsequent disruption of the epithelial barrier is implicated in the pathogenesis of inflammatory bowel disease (IBD). However, the protective systems against such barrier disruption are not fully understood. Here, we show that secretion of luminal glycoprotein 2 (GP2) from pancreatic acinar cells is induced in a TNF-dependent manner in mice with chemically induced colitis. Fecal GP2 concentration is also increased in Crohn's diease patients. Furthermore, pancreas-specific GP2-deficient colitis mice have more severe intestinal inflammation and a larger mucosal E. coli population than do intact mice, indicating that digestive-tract GP2 binds commensal E. coli, preventing epithelial attachment and penetration. Thus, the pancreas-intestinal barrier axis and pancreatic GP2 are important as a first line of defense against adhesive and invasive commensal bacteria during intestinal inflammation.
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Affiliation(s)
- Yosuke Kurashima
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
- Department of Innovative Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
- Division of Gastroenterology, Department of Medicine, CU-UCSD Center for Mucosal Immunology, Allergy and Vaccines, University of California, San Diego, CA, USA.
- Mucosal Immunology and Allergy Therapeutics, Institute for Global Prominent Research, Graduate School of Medicine, Chiba University, Chiba, Japan.
| | - Takaaki Kigoshi
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- Department of Pediatrics, Graduate School of Medicine, Tohoku University, Miyagi, Japan
| | - Sayuri Murasaki
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Fujimi Arai
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Kaoru Shimada
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Natsumi Seki
- Division of Biochemistry, Graduate School of Pharmacological Science, Keio University, Tokyo, Japan
- Research Center for Drug Discovery, Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Yun-Gi Kim
- Research Center for Drug Discovery, Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Koji Hase
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- Division of Biochemistry, Graduate School of Pharmacological Science, Keio University, Tokyo, Japan
| | - Hiroshi Ohno
- Laboratory for Intestinal Ecosystem, RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
- Division of Immunobiology, Department of Medical Life Science, Graduate School of Medical Life Science, Yokohama City University, Kanagawa, Japan
- Intestinal Microbiota Project, Kanagawa Institute of Industrial Science and Technology, Kanagawa, Japan
| | - Kazuya Kawano
- Laboratory for Intestinal Ecosystem, RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
| | - Hiroshi Ashida
- Department of Bacterial Infection and Host Response, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
- Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Toshihiko Suzuki
- Department of Bacterial Infection and Host Response, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Masako Morimoto
- Department of Innovative Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yukari Saito
- Department of Innovative Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Ai Sasou
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yuki Goda
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yoshikazu Yuki
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yutaka Inagaki
- Center for Matrix Biology and Medicine, Graduate School of Medicine, Tokai University, Kanagawa, Japan
| | - Hideki Iijima
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Wataru Suda
- Laboratory for Microbiome Sciences, RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
| | - Masahira Hattori
- Laboratory for Microbiome Sciences, RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
- Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Hiroshi Kiyono
- Department of Mucosal Immunology, The University of Tokyo Distinguished Professor Unit, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
- International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
- Division of Gastroenterology, Department of Medicine, CU-UCSD Center for Mucosal Immunology, Allergy and Vaccines, University of California, San Diego, CA, USA.
- Mucosal Immunology and Allergy Therapeutics, Institute for Global Prominent Research, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Lu Y, Li Y, Li G, Lu H. Identification of potential markers for type 2 diabetes mellitus via bioinformatics analysis. Mol Med Rep 2020; 22:1868-1882. [PMID: 32705173 PMCID: PMC7411335 DOI: 10.3892/mmr.2020.11281] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 01/20/2020] [Indexed: 12/15/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a multifactorial and multigenetic disease, and its pathogenesis is complex and largely unknown. In the present study, microarray data (GSE201966) of β-cell enriched tissue obtained by laser capture microdissection were downloaded, including 10 control and 10 type 2 diabetic subjects. A comprehensive bioinformatics analysis of microarray data in the context of protein-protein interaction (PPI) networks was employed, combined with subcellular location information to mine the potential candidate genes for T2DM and provide further insight on the possible mechanisms involved. First, differential analysis screened 108 differentially expressed genes. Then, 83 candidate genes were identified in the layered network in the context of PPI via network analysis, which were either directly or indirectly linked to T2DM. Of those genes obtained through literature retrieval analysis, 27 of 83 were involved with the development of T2DM; however, the rest of the 56 genes need to be verified by experiments. The functional analysis of candidate genes involved in a number of biological activities, demonstrated that 46 upregulated candidate genes were involved in ‘inflammatory response’ and ‘lipid metabolic process’, and 37 downregulated candidate genes were involved in ‘positive regulation of cell death’ and ‘positive regulation of cell proliferation’. These candidate genes were also involved in different signaling pathways associated with ‘PI3K/Akt signaling pathway’, ‘Rap1 signaling pathway’, ‘Ras signaling pathway’ and ‘MAPK signaling pathway’, which are highly associated with the development of T2DM. Furthermore, a microRNA (miR)-target gene regulatory network and a transcription factor-target gene regulatory network were constructed based on miRNet and NetworkAnalyst databases, respectively. Notably, hsa-miR-192-5p, hsa-miR-124-5p and hsa-miR-335-5p appeared to be involved in T2DM by potentially regulating the expression of various candidate genes, including procollagen C-endopeptidase enhancer 2, connective tissue growth factor and family with sequence similarity 105, member A, protein phosphatase 1 regulatory inhibitor subunit 1 A and C-C motif chemokine receptor 4. Smad5 and Bcl6, as transcription factors, are regulated by ankyrin repeat domain 23 and transmembrane protein 37, respectively, which might also be used in the molecular diagnosis and targeted therapy of T2DM. Taken together, the results of the present study may offer insight for future genomic-based individualized treatment of T2DM and help determine the underlying molecular mechanisms that lead to T2DM.
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Affiliation(s)
- Yana Lu
- Key Laboratory of Dai and Southern Medicine of Xishuangbanna Dai Autonomous Prefecture, Yunnan Branch, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Jinghong, Yunnan 666100, P.R. China
| | - Yihang Li
- Key Laboratory of Dai and Southern Medicine of Xishuangbanna Dai Autonomous Prefecture, Yunnan Branch, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Jinghong, Yunnan 666100, P.R. China
| | - Guang Li
- Key Laboratory of Dai and Southern Medicine of Xishuangbanna Dai Autonomous Prefecture, Yunnan Branch, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Jinghong, Yunnan 666100, P.R. China
| | - Haitao Lu
- Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai 200240, P.R. China
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Williams JA. Cholecystokinin (CCK) Regulation of Pancreatic Acinar Cells: Physiological Actions and Signal Transduction Mechanisms. Compr Physiol 2019; 9:535-564. [PMID: 30873601 DOI: 10.1002/cphy.c180014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pancreatic acinar cells synthesize and secrete about 20 digestive enzymes and ancillary proteins with the processes that match the supply of these enzymes to their need in digestion being regulated by a number of hormones (CCK, secretin and insulin), neurotransmitters (acetylcholine and VIP) and growth factors (EGF and IGF). Of these regulators, one of the most important and best studied is the gastrointestinal hormone, cholecystokinin (CCK). Furthermore, the acinar cell has become a model for seven transmembrane, heterotrimeric G protein coupled receptors to regulate multiple processes by distinct signal transduction cascades. In this review, we briefly describe the chemistry and physiology of CCK and then consider the major physiological effects of CCK on pancreatic acinar cells. The majority of the review is devoted to the physiologic signaling pathways activated by CCK receptors and heterotrimeric G proteins and the functions they affect. The pathways covered include the traditional second messenger pathways PLC-IP3-Ca2+ , DAG-PKC, and AC-cAMP-PKA/EPAC that primarily relate to secretion. Then there are the protein-protein interaction pathways Akt-mTOR-S6K, the three major MAPK pathways (ERK, JNK, and p38 MAPK), and Ca2+ -calcineurin-NFAT pathways that primarily regulate non-secretory processes including biosynthesis and growth, and several miscellaneous pathways that include the Rho family small G proteins, PKD, FAK, and Src that may regulate both secretory and nonsecretory processes but are not as well understood. © 2019 American Physiological Society. Compr Physiol 9:535-564, 2019.
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Affiliation(s)
- John A Williams
- University of Michigan, Departments of Molecular & Integrative Physiology and Internal Medicine (Gastroenterology), Ann Arbor, Michigan, USA
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Ramos-Alvarez I, Lee L, Jensen RT. Cyclic AMP-dependent protein kinase A and EPAC mediate VIP and secretin stimulation of PAK4 and activation of Na +,K +-ATPase in pancreatic acinar cells. Am J Physiol Gastrointest Liver Physiol 2019; 316:G263-G277. [PMID: 30520694 PMCID: PMC6397337 DOI: 10.1152/ajpgi.00275.2018] [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] [Indexed: 01/31/2023]
Abstract
Rat pancreatic acinar cells possess only the p21-activated kinase (PAKs), PAK4 of the group II PAK, and it is activated by gastrointestinal hormones/neurotransmitters stimulating PLC and by a number of growth factors. However, little is known generally of cAMP agents causing PAK4 activation, and there are no studies with gastrointestinal hormones/neurotransmitters activating cAMP cascades. In the present study, we examined the ability of VIP and secretin, which stimulate cAMP generation in pancreatic acini, to stimulate PAK4 activation, the signaling cascades involved, and their possible role in activating sodium-potassium adenosine triphosphatase (Na+,K+-ATPase). PAK4 activation was compared with activation of the well-established cAMP target, cyclic AMP response element binding protein (CREB). Secretin-stimulated PAK4 activation was inhibited by KT-5720 and PKA Type II inhibitor (PKI), protein kinase A (PKA) inhibitors, whereas VIP activation was inhibited by ESI-09 and HJC0197, exchange protein directly activated by cAMP (EPAC) inhibitors. In contrast, both VIP/secretin-stimulated phosphorylation of CREB (pCREB) via EPAC activation; however, it was inhibited by the p44/42 inhibitor PD98059 and the p38 inhibitor SB202190. The specific EPAC agonist 8-CPT-2- O-Me-cAMP as well 8-Br-cAMP and forskolin stimulated PAK4 activation. Secretin/VIP activation of Na+,K+-ATPase, was inhibited by PAK4 inhibitors (PF-3758309, LCH-7749944). These results demonstrate PAK4 is activated in pancreatic acini by stimulation of both VIP-/secretin-preferring receptors, as is CREB. However, they differ in their signaling cascades. Furthermore, PAK4 activation is needed for Na+,K+ATPase activation, which mediates pancreatic fluid secretion. These results, coupled with recent studies reporting PAKs are involved in both pancreatitis/pancreatic cancer growth/enzyme secretion, show that PAK4, similar to PAK2, likely plays an important role in both pancreatic physiological/pathological responses. NEW & NOTEWORTHY Pancreatic acini possess only the group II p21-activated kinase, PAK4, which is activated by PLC-stimulating agents/growth factors and is important in enzyme-secretion/growth/pancreatitis. Little information exists on cAMP-activating agents stimulating group II PAKs. We studied ability/effect of cyclic AMP-stimulating agents [vasoactive intestinal polypeptide (VIP), secretin] on PAK4 activity in rat pancreatic-acini. Both VIP/secretin activated PAK4/CREB, but the cAMP signaling cascades differed for EPAC, MAPK, and PKA pathways. Both hormones require PAK4 activation to stimulate sodium-potassium adenosine triphosphatase activity. This study shows PAK4 plays an important role in VIP-/secretin-stimulated pancreatic fluid secretion and suggests it plays important roles in pancreatic acinar physiological/pathophysiological responses mediated by cAMP-activating agents.
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Affiliation(s)
- Irene Ramos-Alvarez
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Lingaku Lee
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - R. T. Jensen
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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Molecular architecture of mouse and human pancreatic zymogen granules: protein components and their copy numbers. BIOPHYSICS REPORTS 2018; 4:94-103. [PMID: 29756009 PMCID: PMC5937866 DOI: 10.1007/s41048-018-0055-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 10/17/2017] [Indexed: 01/15/2023] Open
Abstract
A molecular model of pancreatic zymogen granule (ZG) is critical for understanding its functions. We have extensively characterized the composition and membrane topology of rat ZG proteins. In this study, we report the development of targeted proteomics approaches to quantify representative mouse and human ZG proteins using LC-SRM and heavy isotope-labeled synthetic peptides. The absolute quantities of mouse Rab3D and VAMP8 were determined as 1242 ± 218 and 2039 ± 151 (mean ± SEM) copies per ZG. The size distribution and the averaged diameter of ZGs 750 ± 23 nm (mean ± SEM) were determined by atomic force microscopy. The absolute quantification of Rab3D was then validated using semi-quantitative Western blotting with purified GST-Rab3D proteins as an internal standard. To extend our proteomics analysis to human pancreas, ZGs were purified using human acini obtained from pancreatic islet transplantation center. One hundred and eighty human ZG proteins were identified for the first time including both the membrane and the content proteins. Furthermore, the copy number per ZG of human Rab3D and VAMP8 were determined to be 1182 ± 45 and 485 ± 15 (mean ± SEM). The comprehensive proteomic analyses of mouse and human pancreatic ZGs have the potential to identify species-specific ZG proteins. The determination of protein copy numbers on pancreatic ZGs represents a significant advance towards building a quantitative molecular model of a prototypical secretory vesicle using targeted proteomics approaches. The identification of human ZG proteins lays a foundation for subsequent studies of altered ZG compositions and secretion in pancreatic diseases.
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Robichaux WG, Cheng X. Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development. Physiol Rev 2018; 98:919-1053. [PMID: 29537337 PMCID: PMC6050347 DOI: 10.1152/physrev.00025.2017] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 12/13/2022] Open
Abstract
This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.
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Affiliation(s)
- William G Robichaux
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
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Bustos MA, Lucchesi O, Ruete MC, Tomes CN. Membrane-permeable Rab27A is a regulator of the acrosome reaction: Role of geranylgeranylation and guanine nucleotides. Cell Signal 2018; 44:72-81. [PMID: 29337043 DOI: 10.1016/j.cellsig.2018.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 12/18/2017] [Accepted: 01/09/2018] [Indexed: 12/11/2022]
Abstract
The acrosome reaction is the regulated exocytosis of mammalian sperm's single secretory granule, essential for fertilization. It relies on small GTPases, the cAMP binding protein Epac, and the SNARE complex, among other components. Here, we describe a novel tool to investigate Rab27-related signaling pathways: a hybrid recombinant protein consisting of human Rab27A fused to TAT, a cell penetrating peptide. With this tool, we aimed to unravel the connection between Rab3, Rab27 and Rap1 in sperm exocytosis and to deepen our understanding about how isoprenylation and guanine nucleotides influence the behaviour of Rab27 in exocytosis. Our results show that TAT-Rab27A-GTP-γ-S permeated into live sperm and triggered acrosomal exocytosis per se when geraylgeranylated but inhibited it when not lipid-modified. Likewise, an impermeant version of Rab27A elicited exocytosis in streptolysin O-permeabilized - but not in non-permeabilized - cells when geranylgeranylated and active. When GDP-β-S substituted for GTP-γ-S, isoprenylated TAT-Rab27A inhibited the acrosome reaction triggered by progesterone and an Epac-selective cAMP analogue, whereas the non-isoprenylated protein did not. Geranylgeranylated TAT-Rab27A-GTP-γ-S promoted the exchange of GDP for GTP on Rab3 and Rap1 detected by far-immunofluorescence with Rab3-GTP and Rap1-GTP binding cassettes. In contrast, TAT-Rab27A lacking isoprenylation or loaded with GDP-β-S prevented the activation of Rab3 and Rap1 elicited by progesterone. Challenging streptolysin O-permeabilized human sperm with calcium increased the population of sperm with Rap1-GTP, Rab3-GTP and Rab27-GTP in the acrosomal region; pretreatment with anti-Rab27 antibodies prevented the activation of all three. The novel findings reported here include: the description of membrane permeant TAT-Rab27A as a trustworthy tool to unveil the regulation of the human sperm acrosome reaction by Rab27 under physiological conditions; that the activation of endogenous Rab27 is required for that of Rab3 and Rap1; and the connection between Epac and Rab27 and between Rab27 and the configuration of the SNARE complex. Moreover, we present direct evidence that Rab27A's lipid modification, and activation/inactivation status correlate with its stimulatory or inhibitory roles in exocytosis.
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Affiliation(s)
- Matías A Bustos
- Instituto de Histologia y Embriologia de Mendoza (IHEM) Dr. Mario H. Burgos-CONICET, Universidad Nacional de Cuyo, casilla de correo 56, 5500 Mendoza, Argentina
| | - Ornella Lucchesi
- Instituto de Histologia y Embriologia de Mendoza (IHEM) Dr. Mario H. Burgos-CONICET, Universidad Nacional de Cuyo, casilla de correo 56, 5500 Mendoza, Argentina
| | - María C Ruete
- Instituto de Histologia y Embriologia de Mendoza (IHEM) Dr. Mario H. Burgos-CONICET, Universidad Nacional de Cuyo, casilla de correo 56, 5500 Mendoza, Argentina
| | - Claudia N Tomes
- Instituto de Histologia y Embriologia de Mendoza (IHEM) Dr. Mario H. Burgos-CONICET, Universidad Nacional de Cuyo, casilla de correo 56, 5500 Mendoza, Argentina.
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Messenger SW, Jones EK, Holthaus CL, Thomas DDH, Cooley MM, Byrne JA, Mareninova OA, Gukovskaya AS, Groblewski GE. Acute acinar pancreatitis blocks vesicle-associated membrane protein 8 (VAMP8)-dependent secretion, resulting in intracellular trypsin accumulation. J Biol Chem 2017; 292:7828-7839. [PMID: 28242757 DOI: 10.1074/jbc.m117.781815] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Indexed: 11/06/2022] Open
Abstract
Zymogen secretory granules in pancreatic acinar cells express two vesicle-associated membrane proteins (VAMP), VAMP2 and -8, each controlling 50% of stimulated secretion. Analysis of secretion kinetics identified a first phase (0-2 min) mediated by VAMP2 and second (2-10 min) and third phases (10-30 min) mediated by VAMP8. Induction of acinar pancreatitis by supramaximal cholecystokinin (CCK-8) stimulation inhibits VAMP8-mediated mid- and late-phase but not VAMP2-mediated early-phase secretion. Elevation of cAMP during supramaximal CCK-8 mitigates third-phase secretory inhibition and acinar damage caused by the accumulation of prematurely activated trypsin. VAMP8-/- acini are resistant to secretory inhibition by supramaximal CCK-8, and despite a 4.5-fold increase in total cellular trypsinogen levels, are fully protected from intracellular trypsin accumulation and acinar damage. VAMP8-mediated secretion is dependent on expression of the early endosomal proteins Rab5, D52, and EEA1. Supramaximal CCK-8 (60 min) caused a 60% reduction in the expression of D52 followed by Rab5 and EEA1 in isolated acini and in in vivo The loss of D52 occurred as a consequence of its entry into autophagic vacuoles and was blocked by lysosomal cathepsin B and L inhibition. Accordingly, adenoviral overexpression of Rab5 or D52 enhanced secretion in response to supramaximal CCK-8 and prevented accumulation of activated trypsin. These data support that acute inhibition of VAMP8-mediated secretion during pancreatitis triggers intracellular trypsin accumulation and loss of the early endosomal compartment. Maintaining anterograde endosomal trafficking during pancreatitis maintains VAMP8-dependent secretion, thereby preventing accumulation of activated trypsin.
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Affiliation(s)
- Scott W Messenger
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Elaina K Jones
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Conner L Holthaus
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Diana D H Thomas
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Michelle M Cooley
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Jennifer A Byrne
- Molecular Oncology Laboratory, Children's Cancer Research Unit, The Children's Hospital at Westmead, New South Wales 2145, Australia, and
| | - Olga A Mareninova
- Department of Veterans Affairs Greater Los Angeles Healthcare System and UCLA, Los Angeles, California 90073
| | - Anna S Gukovskaya
- Department of Veterans Affairs Greater Los Angeles Healthcare System and UCLA, Los Angeles, California 90073
| | - Guy E Groblewski
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706,
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14
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Li C, A. Williams J. Regulation of CCK-induced ERK1/2 activation by PKC epsilon in rat pancreatic acinar cells. AIMS MOLECULAR SCIENCE 2017. [DOI: 10.3934/molsci.2017.4.463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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15
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Quinn SN, Graves SH, Dains-McGahee C, Friedman EM, Hassan H, Witkowski P, Sabbatini ME. Adenylyl cyclase 3/adenylyl cyclase-associated protein 1 (CAP1) complex mediates the anti-migratory effect of forskolin in pancreatic cancer cells. Mol Carcinog 2016; 56:1344-1360. [PMID: 27891679 DOI: 10.1002/mc.22598] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/19/2016] [Accepted: 11/22/2016] [Indexed: 12/19/2022]
Abstract
Pancreatic cancer is one of the most lethal human malignancies. A better understanding of the intracellular mechanism of migration and invasion is urgently needed to develop treatment that will suppress metastases and improve overall survival. Cyclic adenosine monophosphate (cyclic AMP) is a second messenger that has shown to regulate migration and invasion of pancreatic cancer cells. The rise of cyclic AMP suppressed migration and invasion of pancreatic ductal adenocarcinoma cells. Cyclic AMP is formed from cytosolic ATP by the enzyme adenylyl cyclase (AC). There are ten isoforms of ACs; nine are anchored in the plasma membrane and one is soluble. What remains unknown is the extent to which the expression of transmembrane AC isoforms is both modified in pancreatic cancer and mediates the inhibitory effect of forskolin on cell motility. Using real-time PCR analysis, ADCY3 was found to be highly expressed in pancreatic tumor tissues, resulting in a constitutive increase in cyclic AMP levels. On the other hand, ADCY2 was down-regulated. Migration, invasion, and filopodia formation in two different pancreatic adenocarcinoma cell lines, HPAC and PANC-1 deficient in AC1 or AC3, were studied. We found that AC3, upon stimulation with forskolin, enhanced cyclic AMP levels and inhibited cell migration and invasion. Unlikely to be due to a cytotoxic effect, the inhibitory effects of forskolin involved the quick formation of AC3/adenylyl cyclase-associated protein 1 (CAP1)/G-actin complex, which inhibited filopodia formation and cell motility. Using Western blotting analysis, forskolin, through AC3 activation, caused phosphorylation of CREB, but not ERK. The effect of CREB phosphorylation is likely to be associated with long-term signaling changes. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Sierra N Quinn
- Department of Biological Sciences, Augusta University, Augusta, Georgia
| | - Sarai H Graves
- Department of Biological Sciences, Augusta University, Augusta, Georgia
| | | | - Emilee M Friedman
- Department of Biological Sciences, Augusta University, Augusta, Georgia
| | - Humma Hassan
- Department of Biological Sciences, Augusta University, Augusta, Georgia
| | - Piotr Witkowski
- Division of Abdominal Organ Transplantation, Department of Surgery, Pancreatic Islet Transplant Program, The University of Chicago Medical Center, Chicago, Illinois
| | - Maria E Sabbatini
- Department of Biological Sciences, Augusta University, Augusta, Georgia
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16
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Host Epac1 is required for cAMP-mediated invasion by Trypanosoma cruzi. Mol Biochem Parasitol 2016; 211:67-70. [PMID: 27984073 DOI: 10.1016/j.molbiopara.2016.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 02/03/2023]
Abstract
Mechanistic details of the modulation by cAMP of Trypanosoma cruzi host cell invasion remain ill-defined. Here we report that activation of host's Epac1 stimulated invasion, whereas specific pharmacological inhibition or maneuvers that alter Epac1 subcellular localization significantly reduced invasion. Furthermore, while specific activation of host cell PKA showed no effect, its inhibition resulted in an increased invasion, revealing a crosstalk between the PKA and Epac signaling pathways during the process of invasion. Therefore, our data suggests that subcellular localization of Epac might be playing an important role during invasion and that specific activation of the host cell cAMP/Epac1 pathway is required for cAMP-mediated invasion.
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Lucchesi O, Ruete MC, Bustos MA, Quevedo MF, Tomes CN. The signaling module cAMP/Epac/Rap1/PLCε/IP3 mobilizes acrosomal calcium during sperm exocytosis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:544-61. [PMID: 26704387 DOI: 10.1016/j.bbamcr.2015.12.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 11/23/2015] [Accepted: 12/14/2015] [Indexed: 12/29/2022]
Abstract
Exocytosis of the sperm's single secretory granule, or acrosome, is a regulated exocytosis triggered by components of the egg's investments. In addition to external calcium, sperm exocytosis (termed the acrosome reaction) requires cAMP synthesized endogenously and calcium mobilized from the acrosome through IP3-sensitive channels. The relevant cAMP target is Epac. In the first part of this paper, we present a novel tool (the TAT-cAMP sponge) to investigate cAMP-related signaling pathways in response to progesterone as acrosome reaction trigger. The TAT-cAMP sponge consists of the cAMP-binding sites of protein kinase A regulatory subunit RIβ fused to the protein transduction domain TAT of the human immunodeficiency virus-1. The sponge permeated into sperm, sequestered endogenous cAMP, and blocked exocytosis. Progesterone increased the population of sperm with Rap1-GTP, Rab3-GTP, and Rab27-GTP in the acrosomal region; pretreatment with the TAT-cAMP sponge prevented the activation of all three GTPases. In the second part of this manuscript, we show that phospholipase Cε (PLCε) is required for the acrosome reaction downstream of Rap1 and upstream of intra-acrosomal calcium mobilization. Last, we present direct evidence that cAMP, Epac, Rap1, and PLCε are necessary for calcium mobilization from sperm's secretory granule. In summary, we describe here a pathway that connects cAMP to calcium mobilization from the acrosome during sperm exocytosis. Never before had direct evidence for each step of the cascade been put together in the same study.
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Affiliation(s)
- Ornella Lucchesi
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, IHEM-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina
| | - María C Ruete
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, IHEM-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina
| | - Matías A Bustos
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, IHEM-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina
| | - María F Quevedo
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, IHEM-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina
| | - Claudia N Tomes
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, IHEM-CONICET, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina.
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18
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Abstract
Exocytosis is a highly regulated process that consists of multiple functionally, kinetically and/or morphologically definable stages such as recruitment, targeting, tethering and docking of secretory vesicles with the plasma membrane, priming of the fusion machinery and calcium-triggered membrane fusion. After fusion, the membrane around the secretory vesicle is incorporated into the plasma membrane and the granule releases its contents. The proteins involved in these processes belong to several highly conserved families: Rab GTPases, SNAREs (soluble NSF-attachment protein receptors), α-SNAP (α-NSF attachment protein), NSF (N-ethylmaleimide-sensitive factor), Munc13 and -18, complexins and synaptotagmins. In the present article, the molecules of exocytosis are reviewed, using human sperm as a model system. Sperm exocytosis is driven by isoforms of the same proteinaceous fusion machinery mentioned above, with their functions orchestrated in a hierarchically organized and unidirectional signalling cascade. In addition to the universal exocytosis regulator calcium, this cascade includes other second messengers such as diacylglycerol, inositol 1,4,5-trisphosphate and cAMP, as well as the enzymes that synthesize them and their target proteins. Of special interest is the cAMP-binding protein Epac (exchange protein directly activated by cAMP) due in part to its enzymatic activity towards Rap. The activation of Epac and Rap leads to a highly localized calcium signal which, together with assembly of the SNARE complex, governs the final stages of exocytosis. The source of this releasable calcium is the secretory granule itself.
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Messenger SW, Falkowski MA, Thomas DDH, Jones EK, Hong W, Gaisano HY, Giasano HY, Boulis NM, Groblewski GE. Vesicle associated membrane protein 8 (VAMP8)-mediated zymogen granule exocytosis is dependent on endosomal trafficking via the constitutive-like secretory pathway. J Biol Chem 2014; 289:28040-53. [PMID: 25138214 DOI: 10.1074/jbc.m114.593913] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Acinar cell zymogen granules (ZG) express 2 isoforms of the vesicle-associated membrane protein family (VAMP2 and -8) thought to regulate exocytosis. Expression of tetanus toxin to cleave VAMP2 in VAMP8 knock-out (-/-) acini confirmed that VAMP2 and -8 are the primary VAMPs for regulated exocytosis, each contributing ∼50% of the response. Analysis of VAMP8(-/-) acini indicated that although stimulated secretion was significantly reduced, a compensatory increase in constitutive secretion maintained total secretion equivalent to wild type (WT). Using a perifusion system to follow secretion over time revealed VAMP2 mediates an early rapid phase peaking and falling within 2-3 min, whereas VAMP8 controls a second prolonged phase that peaks at 4 min and slowly declines over 20 min to support the protracted secretory response. VAMP8(-/-) acini show increased expression of the endosomal proteins Ti-VAMP7 (2-fold) and Rab11a (4-fold) and their redistribution from endosomes to ZGs. Expression of GDP-trapped Rab11a-S25N inhibited secretion exclusively from the VAMP8 but not the VAMP2 pathway. VAMP8(-/-) acini also showed a >90% decrease in the early endosomal proteins Rab5/D52/EEA1, which control anterograde trafficking in the constitutive-like secretory pathway. In WT acini, short term (14-16 h) culture also results in a >90% decrease in Rab5/D52/EEA1 and a complete loss of the VAMP8 pathway, whereas VAMP2-secretion remains intact. Remarkably, rescue of Rab5/D52/EEA1 expression restored the VAMP8 pathway. Expressed D52 shows extensive colocalization with Rab11a and VAMP8 and partially copurifies with ZG fractions. These results indicate that robust trafficking within the constitutive-like secretory pathway is required for VAMP8- but not VAMP2-mediated ZG exocytosis.
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Affiliation(s)
- Scott W Messenger
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Michelle A Falkowski
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Diana D H Thomas
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Elaina K Jones
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | - Wanjin Hong
- Institute of Molecular and Cellular Biology, National University of Singapore, Singapore 138673
| | | | - Herbert Y Giasano
- Departments of Medicine and Physiology, University of Toronto, Ontario M5S 1A8, Canada, and
| | - Nicholas M Boulis
- Department of Neurosurgery, Georgia Institute of Technology, Atlanta, Georgia 30322
| | - Guy E Groblewski
- From the Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin 53706,
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20
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Vasko MR, Habashy Malty R, Guo C, Duarte DB, Zhang Y, Nicol GD. Nerve growth factor mediates a switch in intracellular signaling for PGE2-induced sensitization of sensory neurons from protein kinase A to Epac. PLoS One 2014; 9:e104529. [PMID: 25126967 PMCID: PMC4134201 DOI: 10.1371/journal.pone.0104529] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/13/2014] [Indexed: 12/21/2022] Open
Abstract
We examined whether nerve growth factor (NGF), an inflammatory mediator that contributes to chronic hypersensitivity, alters the intracellular signaling that mediates the sensitizing actions of PGE2 from activation of protein kinase A (PKA) to exchange proteins directly activated by cAMP (Epacs). When isolated sensory neurons are grown in the absence of added NGF, but not in cultures grown with 30 ng/ml NGF, inhibiting protein kinase A (PKA) activity blocks the ability of PGE2 to augment capsaicin-evoked release of the neuropeptide CGRP and to increase the number of action potentials (APs) evoked by a ramp of current. Growing sensory neurons in culture in the presence of increasing concentrations of NGF increases the expression of Epac2, but not Epac1. An intradermal injection of complete Freund's adjuvant into the rat hindpaw also increases the expression of Epac2, but not Epac1 in the dorsal root ganglia and spinal cord: an effect blocked by intraplantar administration of NGF antibodies. Treating cultures grown in the presence of 30 ng/ml NGF with Epac1siRNA significantly reduced the expression of Epac1, but not Epac2, and did not block the ability of PGE2 to augment capsaicin-evoked release of CGRP from sensory neurons. Exposing neuronal cultures grown in NGF to Epac2siRNAreduced the expression of Epac2, but not Epac1 and prevented the PGE2-induced augmentation of capsaicin and potassium-evoked CGRP release in sensory neurons and the PGE2-induced increase in the number of APs generated by a ramp of current. In neurons grown with no added NGF, Epac siRNAs did not attenuate PGE2-induced sensitization. These results demonstrate that NGF, through increasing Epac2 expression, alters the signaling cascade that mediates PGE2-induced sensitization of sensory neurons, thus providing a novel mechanism for maintaining PGE2-induced hypersensitivity during inflammation.
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Affiliation(s)
- Michael R. Vasko
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- * E-mail:
| | - Ramy Habashy Malty
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt
| | - Chunlu Guo
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Djane B. Duarte
- Faculdade De Ciências da Saúde-FS, Universidade De Brasília-UNB Campus Universitário Darcy, Ribeiro-Asa Norte, Brazil
| | - Yihong Zhang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Grant D. Nicol
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
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Messenger SW, Falkowski MA, Groblewski GE. Ca²⁺-regulated secretory granule exocytosis in pancreatic and parotid acinar cells. Cell Calcium 2014; 55:369-75. [PMID: 24742357 DOI: 10.1016/j.ceca.2014.03.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/04/2014] [Accepted: 03/09/2014] [Indexed: 01/09/2023]
Abstract
Protein secretion from acinar cells of the pancreas and parotid glands is controlled by G-protein coupled receptor activation and generation of the cellular messengers Ca(2+), diacylglycerol and cAMP. Secretory granule (SG) exocytosis shares some common characteristics with nerve, neuroendocrine and endocrine cells which are regulated mainly by elevated cell Ca(2+). However, in addition to diverse signaling pathways, acinar cells have large ∼1 μm diameter SGs (∼30 fold larger diameter than synaptic vesicles), respond to stimulation at slower rates (seconds versus milliseconds), demonstrate significant constitutive secretion, and in isolated acini, undergo sequential compound SG-SG exocytosis at the apical membrane. Exocytosis proceeds as an initial rapid phase that peaks and declines over 3 min followed by a prolonged phase that decays to near basal levels over 20-30 min. Studies indicate the early phase is triggered by Ca(2+) and involves the SG proteins VAMP2 (vesicle associated membrane protein2), Ca(2+)-sensing protein synatotagmin 1 (syt1) and the accessory protein complexin 2. The molecular details for regulation of VAMP8-mediated SG exocytosis and the prolonged phase of secretion are still emerging. Here we review the known regulatory molecules that impact the sequential exocytic process of SG tethering, docking, priming and fusion in acinar cells.
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Affiliation(s)
- Scott W Messenger
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States
| | - Michelle A Falkowski
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States
| | - Guy E Groblewski
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States.
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Sabbatini ME, Gorelick F, Glaser S. Adenylyl cyclases in the digestive system. Cell Signal 2014; 26:1173-81. [PMID: 24521753 DOI: 10.1016/j.cellsig.2014.01.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 01/31/2014] [Indexed: 02/08/2023]
Abstract
Adenylyl cyclases (ACs) are a group of widely distributed enzymes whose functions are very diverse. There are nine known transmembrane AC isoforms activated by Gαs. Each has its own pattern of expression in the digestive system and differential regulation of function by Ca(2+) and other intracellular signals. In addition to the transmembrane isoforms, one AC is soluble and exhibits distinct regulation. In this review, the basic structure, regulation and physiological roles of ACs in the digestive system are discussed.
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Affiliation(s)
| | - Fred Gorelick
- Department of Cell Biology and Medicine, Yale University, United States; VA CT, United States
| | - Shannon Glaser
- Department of Internal Medicine, Scott & White-Digestive Disease Research Center, Texas A&M Health Science Center, Central Texas Veterans Health Care System, United States
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Phosphorylation of the guanine-nucleotide-exchange factor CalDAG-GEFI by protein kinase A regulates Ca(2+)-dependent activation of platelet Rap1b GTPase. Biochem J 2013; 453:115-23. [PMID: 23600630 DOI: 10.1042/bj20130131] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In blood platelets the small GTPase Rap1b is activated by cytosolic Ca2+ and promotes integrin αIIbβ3 inside-out activation and platelet aggregation. cAMP is the major inhibitor of platelet function and antagonizes Rap1b stimulation through a mechanism that remains unclear. In the present study we demonstrate that the Ca2+-dependent exchange factor for Rap1b, CalDAG-GEFI (calcium and diacylglycerol-regulated guanine-nucleotide-exchange factor I), is a novel substrate for the cAMP-activated PKA (protein kinase A). CalDAG-GEFI phosphorylation occurred in intact platelets treated with the cAMP-increasing agent forskolin and was inhibited by the PKA inhibitor H89. Purified recombinant CalDAG-GEFI was also phosphorylated in vitro by the PKA catalytic subunit. By screening a panel of specific serine to alanine residue mutants, we identified Ser116 and Ser586 as PKA phosphorylation sites in CalDAG-GEFI. In transfected HEK (human embryonic kidney)-293 cells, as well as in platelets, forskolin-induced phosphorylation of CalDAG-GEFI prevented the activation of Rap1b induced by the Ca2+ ionophore A23187. In platelets this effect was associated with the inhibition of aggregation. Moreover, cAMP-mediated inhibition of Rap1b was lost in HEK-293 cells transfected with a double mutant of CalDAG-GEFI unable to be phosphorylated by PKA. The results of the present study demonstrate that phosphorylation of CalDAG-GEFI by PKA affects its activity and represents a novel mechanism for cAMP-mediated inhibition of Rap1b in platelets.
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Sabbatini ME, D'Alecy L, Lentz SI, Tang T, Williams JA. Adenylyl cyclase 6 mediates the action of cyclic AMP-dependent secretagogues in mouse pancreatic exocrine cells via protein kinase A pathway activation. J Physiol 2013; 591:3693-707. [PMID: 23753526 DOI: 10.1113/jphysiol.2012.249698] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Both secretin and vasoactive intestinal polypeptide (VIP) receptors are responsible for the activation of adenylyl cyclases (ACs), which increase intracellular cyclic AMP (cAMP) levels in the exocrine pancreas. There are nine membrane-associated isoforms, each with its own pattern of expression and regulation. In this study we sought to establish which AC isoforms play a regulatory role in pancreatic exocrine cells. Using RT-PCR, AC3, AC4, AC6, AC7 and AC9 were found to be expressed in the pancreas. AC3, AC4, AC6 and AC9 were expressed in both pancreatic acini and ducts, whereas AC7 was expressed only in pancreatic ducts. Based on known regulation by intracellular signals, selective inhibitors and stimulators were used to suggest which isoforms play an important role in the induction of cAMP formation. AC6 appeared to be an important isoform because protein kinase A (PKA), PKC and calcium all inhibited VIP-induced cAMP formation, whereas calcineurin or calmodulin did not modify the response to VIP. Mice with genetically deleted AC6 were studied and showed reduced cAMP formation and PKA activation in both isolated pancreatic acini and duct fragments. The absence of AC6 reduced cAMP-dependent secretagogue-stimulated amylase secretion, and abolished fluid secretion in both in vivo and isolated duct fragments. In conclusion, several AC isoforms are expressed in pancreatic acini and ducts. AC6 mediates a significant part of pancreatic amylase and fluid secretion in response to secretin, VIP and forskolin through cAMP/PKA pathway activation.
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Affiliation(s)
- Maria E Sabbatini
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA.
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Abstract
OBJECTIVES This study aimed at T-cell inhibition by immunosuppressants to reduce cell damage and improve the course of severe acute pancreatitis (SAP). METHODS A taurocholate-induced SAP was used and 5 groups were compared: (1) rapamycin + FTY720, (2) rapamycin, (3) FTY720, (4) cortisol, and (5) control: sodium chloride. Drugs were applied intravenously at SAP induction; 6 hours later, rats were killed. Interleukin (IL)-1, IL-6, IL-10, tumor necrosis factor α, platelet-activating factor, amylase, and lipase were measured in serum and myeloperoxidase tissue activity in pancreas, kidney, lung, liver, and spleen. Edema, inflammation, and necrosis were histologically determined in pancreas. CD4/CD8 immunohistochemistry was performed. RESULTS Inflammation was ameliorated in all 4 treated groups. Necrosis development was suppressed by FTY720, FTY720 + rapamycin, and cortisol. IL-6 and IL-10 were significantly lower in these groups. Amylase was higher in all treatment groups compared to the controls except for the cortisol group. Tumor necrosis factor α, lipase, and myeloperoxidase activity were not affected by therapy. CD4+/CD8+ cells were significantly less in FTY720-treated pancreata. CONCLUSION Rapamycin and FTY720 ameliorated the severity of SAP, which may be due to early suppression of helper T cells. FTY720 reduced the development of pancreatic necrosis. The combination of both immunosuppressants did not show advantage to treatment with FTY720 alone.
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Kolodecik TR, Shugrue CA, Thrower EC, Levin LR, Buck J, Gorelick FS. Activation of soluble adenylyl cyclase protects against secretagogue stimulated zymogen activation in rat pancreaic acinar cells. PLoS One 2012; 7:e41320. [PMID: 22844459 PMCID: PMC3402497 DOI: 10.1371/journal.pone.0041320] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 06/20/2012] [Indexed: 01/11/2023] Open
Abstract
An early feature of acute pancreatitis is activation of zymogens, such as trypsinogen, within the pancreatic acinar cell. Supraphysiologic concentrations of the hormone cholecystokinin (CCK; 100 nM), or its orthologue cerulein (CER), induce zymogen activation and elevate levels of cAMP in pancreatic acinar cells. The two classes of adenylyl cyclase, trans-membrane (tmAC) and soluble (sAC), are activated by distinct mechanisms, localize to specific subcellular domains, and can produce locally high concentrations of cAMP. We hypothesized that sAC activity might selectively modulate acinar cell zymogen activation. sAC was identified in acinar cells by PCR and immunoblot. It localized to the apical region of the cell under resting conditions and redistributed intracellularly after treatment with supraphysiologic concentrations of cerulein. In cerulein-treated cells, pre-incubation with a trans-membrane adenylyl cyclase inhibitor did not affect zymogen activation or amylase secretion. However, treatment with a sAC inhibitor (KH7), or inhibition of a downstream target of cAMP, protein kinase A (PKA), significantly enhanced secretagogue-stimulated zymogen activation and amylase secretion. Activation of sAC with bicarbonate significantly inhibited secretagogue-stimulated zymogen activation; this response was decreased by inhibition of sAC or PKA. Bicarbonate also enhanced secretagogue-stimulated cAMP accumulation; this effect was inhibited by KH7. Bicarbonate treatment reduced secretagogue-stimulated acinar cell vacuolization, an early marker of pancreatitis. These data suggest that activation of sAC in the pancreatic acinar cell has a protective effect and reduces the pathologic activation of proteases during pancreatitis.
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Affiliation(s)
- Thomas R. Kolodecik
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Veterans Administration Connecticut Healthcare, West Haven, Connecticut, United States of America
| | - Christine A. Shugrue
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Veterans Administration Connecticut Healthcare, West Haven, Connecticut, United States of America
| | - Edwin C. Thrower
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Veterans Administration Connecticut Healthcare, West Haven, Connecticut, United States of America
| | - Lonny R. Levin
- Department of Pharmacology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Jochen Buck
- Department of Pharmacology, Weill Medical College of Cornell University, New York, New York, United States of America
| | - Fred S. Gorelick
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Veterans Administration Connecticut Healthcare, West Haven, Connecticut, United States of America
- * E-mail:
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Yuen T, Choi SG, Pincas H, Waring DW, Sealfon SC, Turgeon JL. Optimized amplification and single-cell analysis identify GnRH-mediated activation of Rap1b in primary rat gonadotropes. Mol Cell Endocrinol 2012; 350:10-9. [PMID: 22127306 PMCID: PMC3919063 DOI: 10.1016/j.mce.2011.11.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 11/15/2011] [Accepted: 11/15/2011] [Indexed: 10/15/2022]
Abstract
Identifying the early gene program induced by GnRH would help understand how GnRH-activated signaling pathways modulate gonadotrope secretory response. We previously analyzed GnRH-induced early genes in LβT2 cells, however these lack GnRH self-potentiation, a physiological attribute of gonadotropes. To minimize cellular heterogeneity, rat primary pituitary cultures were enriched for gonadotropes by 40-60% using a sedimentation gradient. Given the limited number of gonadotropes, RNA was amplified prior to microarray analysis. Thirty-three genes were up-regulated 40 min after GnRH stimulation. Real-time PCR confirmed regulation of several transcripts including fosB, c-fos, egr-2 and rap1b, a small GTPase and member of the Ras family. GnRH stimulated rap1b gene expression in gonadotropes, measured by a sensitive single cell assay. Immunocytochemistry revealed increased Rap1 protein in GnRH-stimulated gonadotropes. These data establish rap1b as a novel gene rapidly induced by GnRH and a candidate to modulate gonadotropin secretion in rat gonadotropes.
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Affiliation(s)
- Tony Yuen
- Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, United States
| | - Soon Gang Choi
- Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, United States
| | - Hanna Pincas
- Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, United States
| | - Dennis W. Waring
- Division of Endocrinology, Department of Internal Medicine, School of Medicine, University of California, Davis, CA 95616, United States
| | - Stuart C. Sealfon
- Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, United States
| | - Judith L. Turgeon
- Division of Endocrinology, Department of Internal Medicine, School of Medicine, University of California, Davis, CA 95616, United States
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Sans MD, Sabbatini ME, Ernst SA, D'Alecy LG, Nishijima I, Williams JA. Secretin is not necessary for exocrine pancreatic development and growth in mice. Am J Physiol Gastrointest Liver Physiol 2011; 301:G791-8. [PMID: 21852360 PMCID: PMC3220326 DOI: 10.1152/ajpgi.00245.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Adaptive exocrine pancreatic growth is mediated primarily by dietary protein and the gastrointestinal hormone cholecystokinin (CCK). Feeding trypsin inhibitors such as camostat (FOY-305) is known to induce CCK release and stimulate pancreatic growth. However, camostat has also been reported to stimulate secretin release and, because secretin often potentiates the action of CCK, it could participate in the growth response. Our aim was to test the role of secretin in pancreatic development and adaptive growth through the use of C57BL/6 mice with genetic deletion of secretin or secretin receptor. The lack of secretin in the intestine or the secretin receptor in the pancreas was confirmed by RT-PCR. Other related components, such as vasoactive intestinal polypeptide (VIP) receptors (VPAC(1) and VPAC(2)), were not affected. Secretin increased cAMP levels in acini from wild-type (WT) mice but had no effect on acini from secretin receptor-deleted mice, whereas VIP and forskolin still induced a normal response. Secretin in vivo failed to induce fluid secretion in receptor-deficient mice. The pancreas of secretin or secretin receptor-deficient mice was of normal size and histology, indicating that secretin is not necessary for normal pancreatic differentiation or maintenance. When WT mice were fed 0.1% camostat in powdered chow, the pancreas doubled in size in 1 wk, accompanied by parallel increases in protein and DNA. Camostat-fed littermate secretin and secretin receptor-deficient mice had similar pancreatic mass to WT mice. These results indicate that secretin is not required for normal pancreatic development or adaptive growth mediated by CCK.
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Affiliation(s)
| | | | - Stephen A. Ernst
- 2Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan; and
| | | | - Ichiko Nishijima
- 3Environment and Genome Research Center, Tohoku University, Sendai, Japan
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29
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Rah SY, Mushtaq M, Nam TS, Kim SH, Kim UH. Generation of cyclic ADP-ribose and nicotinic acid adenine dinucleotide phosphate by CD38 for Ca2+ signaling in interleukin-8-treated lymphokine-activated killer cells. J Biol Chem 2010; 285:21877-87. [PMID: 20442403 DOI: 10.1074/jbc.m109.066290] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously demonstrated that cyclic ADP-ribose (cADPR) is a calcium signaling messenger in interleukin 8 (IL-8)-induced lymphokine-activated killer (LAK) cells. In this study we examined the possibility that IL-8 activates CD38 to produce another messenger, nicotinic acid adenine dinucleotide phosphate (NAADP), in LAK cells, and we showed that IL-8 induced NAADP formation after cADPR production. These calcium signaling messengers were not produced when LAK cells prepared from CD38 knock-out mice were treated with IL-8, indicating that the synthesis of both NAADP and cADPR is catalyzed by CD38 in LAK cells. Application of cADPR to LAK cells induced NAADP production, whereas NAADP failed to increase intracellular cADPR levels, confirming that the production of cADPR precedes that of NAADP in IL-8-treated LAK cells. Moreover, NAADP increased intracellular Ca(2+) signaling as well as cell migration, which was completely blocked by bafilomycin A1, suggesting that NAADP is generated in lysosome-related organelles after cADPR production. IL-8 or exogenous cADPR, but not NAADP, increased intracellular cAMP levels. cGMP analog, 8-(4-chlorophenylthio)-guanosine 3',5'-cyclic monophosphate, increased both cADPR and NAADP production, whereas the cAMP analog, 8-(4-chlorophenylthio)-cAMP, increased only NAADP production, suggesting that cAMP is essential for IL-8-induced NAADP formation. Furthermore, activation of Rap1, a downstream molecule of Epac, was required for IL-8-induced NAADP formation in LAK cells. Taken together, our data suggest that IL-8-induced NAADP production is mediated by CD38 activation through the actions of cAMP/Epac/protein kinase A/Rap1 in LAK cells and that NAADP plays a key role in Ca(2+) signaling of IL-8-induced LAK cell migration.
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Affiliation(s)
- So-Young Rah
- Departments of Biochemistry, Chonbuk National University Medical School, Jeonju 561-182, Republic of Korea
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Kelly P, Bailey CL, Fueger PT, Newgard CB, Casey PJ, Kimple ME. Rap1 promotes multiple pancreatic islet cell functions and signals through mammalian target of rapamycin complex 1 to enhance proliferation. J Biol Chem 2010; 285:15777-85. [PMID: 20339002 DOI: 10.1074/jbc.m109.069112] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Recent studies have implicated Epac2, a guanine-nucleotide exchange factor for the Rap subfamily of monomeric G proteins, as an important regulator of insulin secretion from pancreatic beta-cells. Although the Epac proteins were originally identified as cAMP-responsive activators of Rap1 GTPases, the role of Rap1 in beta-cell biology has not yet been defined. In this study, we examined the direct effects of Rap1 signaling on beta-cell biology. Using the Ins-1 rat insulinoma line, we demonstrate that activated Rap1A, but not related monomeric G proteins, promotes ribosomal protein S6 phosphorylation. Using isolated rat islets, we show that this signaling event is rapamycin-sensitive, indicating that it is mediated by the mammalian target of rapamycin complex 1-p70 S6 kinase pathway, a known growth regulatory pathway. This newly defined beta-cell signaling pathway acts downstream of cAMP, in parallel with the stimulation of cAMP-dependent protein kinase, to drive ribosomal protein S6 phosphorylation. Activated Rap1A promotes glucose-stimulated insulin secretion, islet cell hypertrophy, and islet cell proliferation, the latter exclusively through mammalian target of rapamycin complex 1, suggesting that Rap1 is an important regulator of beta-cell function. This newly defined signaling pathway may yield unique targets for the treatment of beta-cell dysfunction in diabetes.
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Affiliation(s)
- Patrick Kelly
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Sabbatini ME, Bi Y, Ji B, Ernst SA, Williams JA. CCK activates RhoA and Rac1 differentially through Galpha13 and Galphaq in mouse pancreatic acini. Am J Physiol Cell Physiol 2009; 298:C592-601. [PMID: 19940064 DOI: 10.1152/ajpcell.00448.2009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholecystokinin (CCK) has been shown to activate RhoA and Rac1, as well as reorganize the actin cytoskeleton and, thereby, modify acinar morphology and amylase secretion in mouse pancreatic acini. The aim of the present study was to determine which heterotrimeric G proteins activate RhoA and Rac1 upon CCK stimulation. Galpha(13), but not Galpha(12), was identified in mouse pancreatic acini by RT-PCR and Western blotting. Using specific assays for RhoA and Rac1 activation, we showed that only active Galpha(13) activated RhoA. By contrast, active Galpha(13) and Galpha(q), but not Galpha(s), slightly increased GTP-bound Rac1 levels. A greater increase in Rac1 activation was observed when active Galpha(13) and active Galpha(q) were coexpressed. Galpha(i) was not required for CCK-induced RhoA or Rac1 activation. The regulator of G protein signaling (RGS) domain of p115-Rho guanine nucleotide exchange factor (p115-RGS), a specific inhibitor of Galpha(12/13)-mediated signaling, abolished CCK-stimulated RhoA activation. By contrast, both RGS-2, an inhibitor of Galpha(q), and p115-RGS abolished CCK-induced Rac1 activation, which was PLC pathway-independent. Active Galpha(q) and Galpha(13), but not Galpha(s), induced morphological changes and actin redistribution similar to 1 nM CCK. CCK-induced actin cytoskeletal reorganization was inhibited by RGS-2, but not by p115-RGS, whereas CCK-induced amylase secretion was blocked by both inhibitors. Together, these findings indicate that, in mouse pancreatic acini, Galpha(13) links CCK stimulation to the activation of RhoA, whereas both Galpha(13) and Galpha(q) link CCK stimulation to the activation of Rac1. CCK-induced actin cytoskeletal reorganization is mainly mediated by Galpha(q). By contrast, Galpha(13) and Galpha(q) signaling are required for CCK-induced amylase secretion.
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Affiliation(s)
- Maria E Sabbatini
- Department of Molecular and Integrative Physiology, The University of Michigan, Ann Arbor, Michigan, USA.
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Abstract
Insulin secretion is regulated by a series of complex events generated by various intracellular signals including Ca(2+), ATP, cAMP and phospholipid-derived signals. Glucose-stimulated insulin secretion is the principal mode of insulin secretion, and the mechanism potentiating the secretion is critical for physiological responses. Among the various intracellular signals involved, cAMP is particularly important for amplifying insulin secretion. Recently, glucagon-like peptide-1 (GLP-1) analogues and dipeptidyl peptidase-IV (DPP-IV) inhibitors have been developed as new antidiabetic drugs. These drugs all act through cAMP signalling in pancreatic beta-cells. Until recently, cAMP was generally thought to potentiate insulin secretion through protein kinase A (PKA) phosphorylation of proteins associated with the secretory process. However, it is now known that in addition to PKA, cAMP has other targets such as Epac (also referred to as cAMP-GEF). The variety of the effects mediated by cAMP signalling may be linked to cAMP compartmentation in the pancreatic beta-cells.
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Affiliation(s)
- S Seino
- Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Hyogo, Japan.
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Hamagami KI, Sakurai Y, Shintani N, Higuchi N, Ikeda K, Hashimoto H, Suzuki A, Kiyama H, Baba A. Over-expression of pancreatic pituitary adenylate cyclase-activating polypeptide (PACAP) aggravates cerulein-induced acute pancreatitis in mice. J Pharmacol Sci 2009; 110:451-8. [PMID: 19672038 DOI: 10.1254/jphs.09119fp] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Development of human chronic pancreatitis is associated with intrapancreatic accumulation of pituitary adenylate cyclase-activating polypeptide (PACAP) accompanied with an altered inflammatory response (Michalski et al., Am J Physiol Gastrointest Liver Physiol. 2008;294:G50-G57). To investigate the role of pancreatic PACAP in the development of acute pancreatitis, we employed transgenic mice over-expressing PACAP in pancreatic beta-cells (PACAP-Tg). In comparison to wild-type mice, PACAP-Tg mice exhibited more severe pathophysiological signs of the cerulein-induced pancreatitis at 12 h, as evidenced by higher serum amylase and lipase levels accompanied by the exacerbation of pancreatic edema, necrosis, and inflammation. Cerulein treatment increased mRNA expression of several proinflammatory cytokines (TNFalpha, IL-1beta, and IL-6) at 12 h with similar magnitude both in wild-type and PACAP-Tg mice. In addition, the mRNA and protein levels of regenerating gene III beta (RegIIIbeta), a key factor in the pancreatic response to acute pancreatitis, were up-regulated at 24 h in wild-type mice upon cerulein administration, whereas they were attenuated in PACAP-Tg mice. These data indicate that over-expressed PACAP in pancreas enhances the cerulein-induced inflammatory response of both acinar cells, leading to aggravated acute pancreatitis, which was accompanied by a down-regulation of RegIIIbeta, an anti-inflammatory factor.
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Affiliation(s)
- Ken-ichi Hamagami
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, Japan
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Abstract
PURPOSE OF REVIEW This review focuses on studies from the past year that have greatly advanced our understanding of molecular and cellular regulation of pancreatic acinar cell function. RECENT FINDINGS Recent advances focus on signals dictating pancreatic development, acinar cell fate, pancreatic growth, and secretion. Regeneration of acinar cells after pancreatitis depends on expression of embryonic signals in mature acinar cells. In this setting, acinar cells can also transdifferentiate into adipose cells. With the forced induction of certain early and endocrine-driving transcription factors, acinar cells can also transdifferentiate into beta-cells. There has also been an increased understanding of acinar-to-ductal metaplasia and the subsequent formation of pancreatic intraepithelial neoplasia lesions. Multiple proteins involved in secretion have been characterized, including small guanosine triphosphate-binding proteins, soluble N-ethylmaleimide-sensitive factor attachment proteins, and ion channels. SUMMARY These findings demonstrate the regenerative potential of the acinar cell to mitigate injurious states such as pancreatitis. The ability of acinar cells to transdifferentiate into beta-cells could potentially provide a treatment for diabetes. Finally, the results might be helpful in preventing malignant transformation events arising from the acinar cell. Developments in proteomics and computer modeling could expand our view of proteins mediating acinar cell function.
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Branham MT, Bustos MA, De Blas GA, Rehmann H, Zarelli VEP, Treviño CL, Darszon A, Mayorga LS, Tomes CN. Epac activates the small G proteins Rap1 and Rab3A to achieve exocytosis. J Biol Chem 2009; 284:24825-39. [PMID: 19546222 DOI: 10.1074/jbc.m109.015362] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Exocytosis of the acrosome (the acrosome reaction) relies on cAMP production, assembly of a proteinaceous fusion machinery, calcium influx from the extracellular medium, and mobilization from inositol 1,4,5-trisphosphate-sensitive intracellular stores. Addition of cAMP to human sperm suspensions bypasses some of these requirements and elicits exocytosis in a protein kinase A- and extracellular calcium-independent manner. The relevant cAMP target is Epac, a guanine nucleotide exchange factor for the small GTPase Rap. We show here that a soluble adenylyl cyclase synthesizes the cAMP required for the acrosome reaction. Epac stimulates the exchange of GDP for GTP on Rap1, upstream of a phospholipase C. The Epac-selective cAMP analogue 8-pCPT-2'-O-Me-cAMP induces a phospholipase C-dependent calcium mobilization in human sperm suspensions. In addition, our studies identify a novel connection between cAMP and Rab3A, a secretory granule-associated protein, revealing that the latter functions downstream of soluble adenylyl cyclase/cAMP/Epac but not of Rap1. Challenging sperm with calcium or 8-pCPT-2'-O-Me-cAMP boosts the exchange of GDP for GTP on Rab3A. Recombinant Epac does not release GDP from Rab3A in vitro, suggesting that the Rab3A-GEF activation by cAMP/Epac in vivo is indirect. We propose that Epac sits at a critical point during the exocytotic cascade after which the pathway splits into two limbs, one that assembles the fusion machinery into place and another that elicits intracellular calcium release.
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Affiliation(s)
- María T Branham
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología-Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, CC 56, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
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Krajacic A, Ghosh M, Puentes R, Pearse DD, Fouad K. Advantages of delaying the onset of rehabilitative reaching training in rats with incomplete spinal cord injury. Eur J Neurosci 2009; 29:641-51. [PMID: 19222562 DOI: 10.1111/j.1460-9568.2008.06600.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have previously reported that rehabilitative reaching training initiated 4 days following an incomplete cervical spinal cord injury (SCI) in adult rats promotes plasticity and task-specific recovery. This training, however, also resulted in impairments in an untrained task. Here we examined whether delaying the rehabilitative training following cervical SCI is still effective in promoting task-specific recovery, but circumvents impairments in an untrained task, comparable to what has been reported in stroke models. Therefore, reaching training for a period of 6 weeks was initiated at Day 12 following a cervical dorso-lateral quadrant lesion. Thereupon the rats' ability to reach and to walk on a horizontal ladder (i.e. the untrained task) was assessed, and 8 weeks post-injury cortical map changes were investigated through microstimulation. Further, we examined changes in phospho protein kinase A (pPKA) levels following an immediate and a delayed onset of reaching training in rats with cervical SCI. We found that delayed rehabilitative training was comparably effective as immediate training in promoting task-specific recovery and sprouting of injured axons. Importantly, delayed training did not impair the performance on horizontal ladder walking. Strikingly, only delayed reaching training restored cortical PKA levels that had dropped significantly over 2 weeks post-injury. Additionally, delayed training did not influence cortical map changes following injury, but decreased white matter damage. In conclusion, our results show that a short delay in the onset of training in a forelimb task significantly alters our outcome measures, which should be considered in future rehabilitative approaches.
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Niimura M, Miki T, Shibasaki T, Fujimoto W, Iwanaga T, Seino S. Critical role of the N-terminal cyclic AMP-binding domain of Epac2 in its subcellular localization and function. J Cell Physiol 2009; 219:652-8. [PMID: 19170062 DOI: 10.1002/jcp.21709] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
cAMP is a well-known regulator of exocytosis, and cAMP-GEFII (Epac2) is involved in the potentiation of cAMP-dependent, PKA-independent regulated exocytosis in secretory cells. However, the mechanisms of its action are not fully understood. In the course of our study of Epac2 knockout mice, we identified a novel splicing variant of Epac2, which we designate Epac2B, while renaming the previously identified Epac2 Epac2A. Epac2B, which lacks the first cAMP-binding domain A in the N-terminus but has the second cAMP-binding domain B of Epac2A, possesses GEF activity towards Rap1, as was found for Epac2A. Immunocytochemical analysis revealed that exogenously introduced Epac2A into insulin-secreting MIN6 cells was localized near the plasma membrane, while Epac2B was found primarily in the cytoplasm. Interestingly, cAMP-binding domain A alone introduced into MIN6 cells was also localized near the plasma membrane. In MIN6 cells, Epac2A was involved in triggering hormone secretion by stimulation with 5.6 mM glucose plus 1 mM 8-Bromo-cAMP, but Epac2B was not. The addition of a membrane-targeting signal to the N-terminus of Epac2B was able to mimic the effect of Epac2A on hormone secretion. Thus, the present study indicates that the N-terminal cAMP-binding domain A of Epac2A plays a critical role in determining its subcellular localization and potentiating insulin secretion by cAMP. J. Cell. Physiol. 219: 652-658, 2009. (c) 2009 Wiley-Liss, Inc.
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Affiliation(s)
- Manabu Niimura
- Division of Cellular and Molecular Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
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Williams JA, Chen X, Sabbatini ME. Small G proteins as key regulators of pancreatic digestive enzyme secretion. Am J Physiol Endocrinol Metab 2009; 296:E405-14. [PMID: 19088252 PMCID: PMC2660147 DOI: 10.1152/ajpendo.90874.2008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Small GTP-binding (G) proteins act as molecular switches to regulate a number of cellular processes, including vesicular transport. Emerging evidence indicates that small G proteins regulate a number of steps in the secretion of pancreatic acinar cells. Diverse small G proteins have been localized at discrete compartments along the secretory pathway and particularly on the secretory granule. Rab3D, Rab27B, and Rap1 are present on the granule membrane and play a role in the steps leading up to exocytosis. Whether the function of these G proteins is simply to ensure appropriate targeting or if they are involved as regulatory molecules is discussed. Most evidence suggests that Rab3D and Rab27B play a role in tethering the secretory granule to its target membrane. Other Rabs have been identified on the secretory granule that are associated with different steps in the secretory pathway. The Rho family small G proteins RhoA and Rac1 also regulate secretion through remodeling of the actin cytoskeleton. Possible mechanisms for regulation of these G proteins and their effector molecules are considered.
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Affiliation(s)
- John A Williams
- Dept. of Molecular and Integrative Physiology, Univ. of Michigan, Ann Arbor, MI 48109, USA.
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