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Ruan H, Mandla R, Ravi N, Galang G, Soe AW, Olgin JE, Lang D, Vedantham V. Cholecystokinin-A signaling regulates automaticity of pacemaker cardiomyocytes. Front Physiol 2023; 14:1284673. [PMID: 38179138 PMCID: PMC10764621 DOI: 10.3389/fphys.2023.1284673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 12/08/2023] [Indexed: 01/06/2024] Open
Abstract
Aims: The behavior of pacemaker cardiomyocytes (PCs) in the sinoatrial node (SAN) is modulated by neurohormonal and paracrine factors, many of which signal through G-protein coupled receptors (GPCRs). The aims of the present study are to catalog GPCRs that are differentially expressed in the mammalian SAN and to define the acute physiological consequences of activating the cholecystokinin-A signaling system in isolated PCs. Methods and results: Using bulk and single cell RNA sequencing datasets, we identify a set of GPCRs that are differentially expressed between SAN and right atrial tissue, including several whose roles in PCs and in the SAN have not been thoroughly characterized. Focusing on one such GPCR, Cholecystokinin-A receptor (CCKAR), we demonstrate expression of Cckar mRNA specifically in mouse PCs, and further demonstrate that subsets of SAN fibroblasts and neurons within the cardiac intrinsic nervous system express cholecystokinin, the ligand for CCKAR. Using mouse models, we find that while baseline SAN function is not dramatically affected by loss of CCKAR, the firing rate of individual PCs is slowed by exposure to sulfated cholecystokinin-8 (sCCK-8), the high affinity ligand for CCKAR. The effect of sCCK-8 on firing rate is mediated by reduction in the rate of spontaneous phase 4 depolarization of PCs and is mitigated by activation of beta-adrenergic signaling. Conclusion: (1) PCs express many GPCRs whose specific roles in SAN function have not been characterized, (2) Activation of the cholecystokinin-A signaling pathway regulates PC automaticity.
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Affiliation(s)
- Hongmei Ruan
- *Correspondence: Hongmei Ruan, Vasanth Vedantham,
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Ruan H, Mandla R, Ravi N, Galang G, Soe AW, Olgin JE, Lang D, Vedantham V. Cholecystokinin-A Signaling Regulates Automaticity of Pacemaker Cardiomyocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.24.525392. [PMID: 36747643 PMCID: PMC9900793 DOI: 10.1101/2023.01.24.525392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Aims The behavior of pacemaker cardiomyocytes (PCs) in the sinoatrial node (SAN) is modulated by neurohormonal and paracrine factors, many of which signal through G-protein coupled receptors (GPCRs). The aims of the present study are to catalog GPCRs that are differentially expressed in the mammalian SAN and to define the acute physiological consequences of activating the cholecystokinin-A signaling system in isolated PCs. Methods and Results Using bulk and single cell RNA sequencing datasets, we identify a set of GPCRs that are differentially expressed between SAN and right atrial tissue, including several whose roles in PCs and in the SAN have not been thoroughly characterized. Focusing on one such GPCR, Cholecystokinin-A receptor (CCK A R), we demonstrate expression of Cckar mRNA specifically in mouse PCs, and further demonstrate that subsets of SAN fibroblasts and neurons within the cardiac intrinsic nervous system express cholecystokinin, the ligand for CCK A R. Using mouse models, we find that while baseline SAN function is not dramatically affected by loss of CCK A R, the firing rate of individual PCs is slowed by exposure to sulfated cholecystokinin-8 (sCCK-8), the high affinity ligand for CCK A R. The effect of sCCK-8 on firing rate is mediated by reduction in the rate of spontaneous phase 4 depolarization of PCs and is mitigated by activation of beta-adrenergic signaling. Conclusions (1) PCs express many GPCRs whose specific roles in SAN function have not been characterized, (2) Activation of the the cholecystokinin-A signaling pathway regulates PC automaticity.
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Ramos-Alvarez I, Lee L, Jensen RT. Cofilin activation in pancreatic acinar cells plays a pivotal convergent role for mediating CCK-stimulated enzyme secretion and growth. Front Physiol 2023; 14:1147572. [PMID: 37138671 PMCID: PMC10149936 DOI: 10.3389/fphys.2023.1147572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/05/2023] [Indexed: 05/05/2023] Open
Abstract
Introduction: The actin regulatory protein, cofilin plays a key signaling role in many cells for numerous cellular responses including in proliferation, development, motility, migration, secretion and growth. In the pancreas it is important in islet insulin secretion, growth of pancreatic cancer cells and in pancreatitis. However, there are no studies on its role or activation in pancreatic acinar cells. Methods: To address this question, we studied the ability of CCK to activate cofilin in pancreatic acinar cells, AR42J cells and CCK1-R transfected Panc-1 cells, the signaling cascades involved and its effect on enzyme secretion and MAPK activation, a key mediator of pancreatic growth. Results: CCK (0.3 and 100 nM), TPA, carbachol, Bombesin, secretin and VIP decreased phospho-cofilin (i.e., activate cofilin) and both phospho-kinetic and inhibitor studies of cofilin, LIM kinase (LIMK) and Slingshot Protein Phosphatase (SSH1) demonstrated these conventional activators of cofilin were not involved. Serine phosphatases inhibitors (calyculin A and okadaic acid), however inhibited CCK/TPA-cofilin activation. Studies of various CCK-activated signaling cascades showed activation of PKC/PKD, Src, PAK4, JNK, ROCK mediated cofilin activation, but not PI3K, p38, or MEK. Furthermore, using both siRNA and cofilin inhibitors, cofilin activation was shown to be essential for CCK-mediated enzyme secretion and MAPK activation. Conclusion: These results support the conclusion that cofilin activation plays a pivotal convergent role for various cell signaling cascades in CCK mediated growth/enzyme secretion in pancreatic acini.
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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, MD, United States
| | - Lingaku Lee
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
- National Kyushu Cancer Center, Department of Hepato-Biliary-Pancreatology, Fukuoka, Japan
| | - Robert T. Jensen
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Robert T. Jensen,
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Wang Y, Gai S, Zhang W, Huang X, Ma S, Huo Y, Wu Y, Tu H, Pin JP, Rondard P, Xu C, Liu J. The GABA B receptor mediates neuroprotection by coupling to G 13. Sci Signal 2021; 14:eaaz4112. [PMID: 34665640 DOI: 10.1126/scisignal.aaz4112] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Yunyun Wang
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Siyu Gai
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Wenhua Zhang
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Xuetao Huang
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Shumin Ma
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Yujia Huo
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Yichen Wu
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Haijun Tu
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Chanjuan Xu
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Jianfeng Liu
- Cellular Signaling laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China.,Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, 510005 Guangzhou, China
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Liu Q, Yang D, Zhuang Y, Croll TI, Cai X, Dai A, He X, Duan J, Yin W, Ye C, Zhou F, Wu B, Zhao Q, Xu HE, Wang MW, Jiang Y. Ligand recognition and G-protein coupling selectivity of cholecystokinin A receptor. Nat Chem Biol 2021; 17:1238-1244. [PMID: 34556862 PMCID: PMC8604728 DOI: 10.1038/s41589-021-00841-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 06/24/2021] [Indexed: 02/08/2023]
Abstract
Cholecystokinin A receptor (CCKAR) belongs to family A G-protein-coupled receptors and regulates nutrient homeostasis upon stimulation by cholecystokinin (CCK). It is an attractive drug target for gastrointestinal and metabolic diseases. One distinguishing feature of CCKAR is its ability to interact with a sulfated ligand and to couple with divergent G-protein subtypes, including Gs, Gi and Gq. However, the basis for G-protein coupling promiscuity and ligand recognition by CCKAR remains unknown. Here, we present three cryo-electron microscopy structures of sulfated CCK-8-activated CCKAR in complex with Gs, Gi and Gq heterotrimers, respectively. CCKAR presents a similar conformation in the three structures, whereas conformational differences in the 'wavy hook' of the Gα subunits and ICL3 of the receptor serve as determinants in G-protein coupling selectivity. Our findings provide a framework for understanding G-protein coupling promiscuity by CCKAR and uncover the mechanism of receptor recognition by sulfated CCK-8.
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Affiliation(s)
- Qiufeng Liu
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Dehua Yang
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China ,grid.9227.e0000000119573309The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Youwen Zhuang
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Tristan I. Croll
- grid.5335.00000000121885934Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Xiaoqing Cai
- grid.9227.e0000000119573309The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Antao Dai
- grid.9227.e0000000119573309The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xinheng He
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Jia Duan
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Wanchao Yin
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Chenyu Ye
- grid.8547.e0000 0001 0125 2443School of Pharmacy, Fudan University, Shanghai, China
| | - Fulai Zhou
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Beili Wu
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China ,grid.440637.20000 0004 4657 8879School of Life Science and Technology, ShanghaiTech University, Shanghai, China ,grid.9227.e0000000119573309CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China
| | - Qiang Zhao
- grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China ,grid.9227.e0000000119573309CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China ,grid.9227.e0000000119573309State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - H. Eric Xu
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China ,grid.440637.20000 0004 4657 8879School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ming-Wei Wang
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China ,grid.9227.e0000000119573309The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China ,grid.8547.e0000 0001 0125 2443School of Pharmacy, Fudan University, Shanghai, China ,grid.440637.20000 0004 4657 8879School of Life Science and Technology, ShanghaiTech University, Shanghai, China ,grid.8547.e0000 0001 0125 2443School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yi Jiang
- grid.9227.e0000000119573309The CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
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Damacharla D, Thamilselvan V, Zhang X, Mestareehi A, Yi Z, Kowluru A. Quantitative proteomics reveals novel interaction partners of Rac1 in pancreatic β-cells: Evidence for increased interaction with Rac1 under hyperglycemic conditions. Mol Cell Endocrinol 2019; 494:110489. [PMID: 31202817 PMCID: PMC6686664 DOI: 10.1016/j.mce.2019.110489] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/11/2019] [Accepted: 06/11/2019] [Indexed: 11/19/2022]
Abstract
Rac1, a small G protein, regulates physiological insulin secretion from the pancreatic β-cell. Interestingly, Rac1 has also been implicated in the onset of metabolic dysfunction of the β-cell under the duress of hyperglycemia (HG). This study is aimed at the identification of interaction partners of Rac1 in β-cells under basal and HG conditions. Using co-immunoprecipitation and UPLC-ESI-MS/MS, we identified 324 Rac1 interaction partners in INS-1832/13 cells, which represent the largest Rac1 interactome to date. Furthermore, we identified 27 interaction partners that exhibited increased association with Rac1 in β-cells exposed to HG. Western blotting (INS-1832/13 cells, rat islets and human islets) and co-immunoprecipitation (INS-1832/13 cells) further validated the identity of these Rac1 interaction partners including regulators of GPCR-G protein-effector coupling in the islet. These data form the basis for future investigations on contributory roles of these Rac1-specific signaling pathways in islet β-cell function in health and diabetes.
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Affiliation(s)
- Divyasri Damacharla
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Vijayalakshmi Thamilselvan
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Xiangmin Zhang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Aktham Mestareehi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Zhengping Yi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA; Center for Translational Research in Diabetes, Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, 48201, USA.
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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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Yano K, Shimizu S, Tomono T, Ogihara T. Gastrointestinal Hormone Cholecystokinin Increases P-Glycoprotein Membrane Localization and Transport Activity in Caco-2 Cells. J Pharm Sci 2017; 106:2650-2656. [DOI: 10.1016/j.xphs.2017.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/17/2017] [Accepted: 04/03/2017] [Indexed: 01/11/2023]
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Neuman JC, Fenske RJ, Kimple ME. Dietary polyunsaturated fatty acids and their metabolites: Implications for diabetes pathophysiology, prevention, and treatment. NUTRITION AND HEALTHY AGING 2017; 4:127-140. [PMID: 28447067 PMCID: PMC5391679 DOI: 10.3233/nha-160004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Affiliation(s)
- Joshua C. Neuman
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Rachel J. Fenske
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
| | - Michelle E. Kimple
- Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Department of Medicine, Division of Endocrinology, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
- Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA
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Miller LJ, Desai AJ. Metabolic Actions of the Type 1 Cholecystokinin Receptor: Its Potential as a Therapeutic Target. Trends Endocrinol Metab 2016; 27:609-619. [PMID: 27156041 PMCID: PMC4992613 DOI: 10.1016/j.tem.2016.04.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/31/2016] [Accepted: 04/05/2016] [Indexed: 12/13/2022]
Abstract
Cholecystokinin (CCK) regulates appetite and reduces food intake by activating the type 1 CCK receptor (CCK1R). Attempts to develop CCK1R agonists for obesity have yielded active agents that have not reached clinical practice. Here we discuss why, along with new strategies to target CCK1R more effectively. We examine signaling events and the possibility of developing agents that exhibit ligand-directed bias, to dissociate satiety activity from undesirable side effects. Potential allosteric sites of modulation are also discussed, along with desired properties of a positive allosteric modulator (PAM) without intrinsic agonist action as another strategy to treat obesity. These new types of CCK1R-active drugs could be useful as standalone agents or as part of a rational drug combination for management of obesity.
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Affiliation(s)
- Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA.
| | - Aditya J Desai
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA
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Tripathi S, Flobak Å, Chawla K, Baudot A, Bruland T, Thommesen L, Kuiper M, Lægreid A. The gastrin and cholecystokinin receptors mediated signaling network: a scaffold for data analysis and new hypotheses on regulatory mechanisms. BMC SYSTEMS BIOLOGY 2015. [PMID: 26205660 PMCID: PMC4513977 DOI: 10.1186/s12918-015-0181-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Background The gastrointestinal peptide hormones cholecystokinin and gastrin exert their biological functions via cholecystokinin receptors CCK1R and CCK2R respectively. Gastrin, a central regulator of gastric acid secretion, is involved in growth and differentiation of gastric and colonic mucosa, and there is evidence that it is pro-carcinogenic. Cholecystokinin is implicated in digestion, appetite control and body weight regulation, and may play a role in several digestive disorders. Results We performed a detailed analysis of the literature reporting experimental evidence on signaling pathways triggered by CCK1R and CCK2R, in order to create a comprehensive map of gastrin and cholecystokinin-mediated intracellular signaling cascades. The resulting signaling map captures 413 reactions involving 530 molecular species, and incorporates the currently available knowledge into one integrated signaling network. The decomposition of the signaling map into sub-networks revealed 18 modules that represent higher-level structures of the signaling map. These modules allow a more compact mapping of intracellular signaling reactions to known cell behavioral outcomes such as proliferation, migration and apoptosis. The integration of large-scale protein-protein interaction data to this literature-based signaling map in combination with topological analyses allowed us to identify 70 proteins able to increase the compactness of the map. These proteins represent experimentally testable hypotheses for gaining new knowledge on gastrin- and cholecystokinin receptor signaling. The CCKR map is freely available both in a downloadable, machine-readable SBML-compatible format and as a web resource through PAYAO (http://sblab.celldesigner.org:18080/Payao11/bin/). Conclusion We have demonstrated how a literature-based CCKR signaling map together with its protein interaction extensions can be analyzed to generate new hypotheses on molecular mechanisms involved in gastrin- and cholecystokinin-mediated regulation of cellular processes. Electronic supplementary material The online version of this article (doi:10.1186/s12918-015-0181-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sushil Tripathi
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7489, Trondheim, Norway.
| | - Åsmund Flobak
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7489, Trondheim, Norway.
| | - Konika Chawla
- Department of Biology, Norwegian University of Science and Technology (NTNU), N-7491, Trondheim, Norway.
| | - Anaïs Baudot
- I2M, Marseilles Institute of Mathematics CNRS - AMU, Case 907, 13288, Marseille, Cedex 9, France.
| | - Torunn Bruland
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7489, Trondheim, Norway.
| | - Liv Thommesen
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7489, Trondheim, Norway. .,Department of Technology, Sør-Trøndelag University College, N-7004, Trondheim, Norway.
| | - Martin Kuiper
- Department of Biology, Norwegian University of Science and Technology (NTNU), N-7491, Trondheim, Norway.
| | - Astrid Lægreid
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7489, Trondheim, Norway. .,Institute of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology (NTNU), N-7489, Trondheim, Norway.
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Masià-Balagué M, Izquierdo I, Garrido G, Cordomí A, Pérez-Benito L, Miller NLG, Schlaepfer DD, Gigoux V, Aragay AM. Gastrin-stimulated Gα13 Activation of Rgnef Protein (ArhGEF28) in DLD-1 Colon Carcinoma Cells. J Biol Chem 2015; 290:15197-209. [PMID: 25922072 PMCID: PMC4463461 DOI: 10.1074/jbc.m114.628164] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 04/27/2015] [Indexed: 12/15/2022] Open
Abstract
The guanine nucleotide exchange factor Rgnef (also known as ArhGEF28 or p190RhoGEF) promotes colon carcinoma cell motility and tumor progression via interaction with focal adhesion kinase (FAK). Mechanisms of Rgnef activation downstream of integrin or G protein-coupled receptors remain undefined. In the absence of a recognized G protein signaling homology domain in Rgnef, no proximal linkage to G proteins was known. Utilizing multiple methods, we have identified Rgnef as a new effector for Gα13 downstream of gastrin and the type 2 cholecystokinin receptor. In DLD-1 colon carcinoma cells depleted of Gα13, gastrin-induced FAK Tyr(P)-397 and paxillin Tyr(P)-31 phosphorylation were reduced. RhoA GTP binding and promoter activity were increased by Rgnef in combination with active Gα13. Rgnef co-immunoprecipitated with activated Gα13Q226L but not Gα12Q229L. The Rgnef C-terminal (CT, 1279-1582) region was sufficient for co-immunoprecipitation, and Rgnef-CT exogenous expression prevented Gα13-stimulated SRE activity. A domain at the C terminus of the protein close to the FAK binding domain is necessary to bind to Gα13. Point mutations of Rgnef-CT residues disrupt association with active Gα13 but not Gαq. These results show that Rgnef functions as an effector of Gα13 signaling and that this linkage may mediate FAK activation in DLD-1 colon carcinoma cells.
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Affiliation(s)
- Miriam Masià-Balagué
- From the Molecular Biology Institute of Barcelona, Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Ismael Izquierdo
- From the Molecular Biology Institute of Barcelona, Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Georgina Garrido
- From the Molecular Biology Institute of Barcelona, Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Arnau Cordomí
- the Departament de Pediatria, Unitat de Bioestadística, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Laura Pérez-Benito
- the Departament de Pediatria, Unitat de Bioestadística, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Nichol L G Miller
- the Université Paul Sabatier Réceptologie et Ciblage Thérapeutique en Cancérologie, INSERM, Toulouse, France, and
| | - David D Schlaepfer
- the Université Paul Sabatier Réceptologie et Ciblage Thérapeutique en Cancérologie, INSERM, Toulouse, France, and
| | - Véronique Gigoux
- the Moores Cancer Center, University of California at San Diego, La Jolla, California 92093
| | - Anna M Aragay
- From the Molecular Biology Institute of Barcelona, Spanish National Research Council (CSIC), 08028 Barcelona, Spain,
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14
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Gastrointestinal hormones/neurotransmitters and growth factors can activate P21 activated kinase 2 in pancreatic acinar cells by novel mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:2371-82. [PMID: 25979836 DOI: 10.1016/j.bbamcr.2015.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Revised: 04/28/2015] [Accepted: 05/07/2015] [Indexed: 12/15/2022]
Abstract
P-21-activated kinases (PAKs) are serine/threonine kinases comprising six isoforms divided in two groups, group-I (PAK1-3)/group-II (PAK4-6) which play important roles in cell cytoskeletal dynamics, survival, secretion and proliferation and are activated by diverse stimuli. However, little is known about PAKs ability to be activated by gastrointestinal (GI) hormones/neurotransmitters/growth-factors. We used rat pancreatic acini to explore the ability of GI-hormones/neurotransmitters/growth-factors to activate Group-I-PAKs and the signaling cascades involved. Only PAK2 was present in acini. PAK2 was activated by some pancreatic growth-factors [EGF, PDGF, bFGF], by secretagogues activating phospholipase-C (PLC) [CCK, carbachol, bombesin] and by post-receptor stimulants activating PKC [TPA], but not agents only mobilizing cellular calcium or increasing cyclic AMP. CCK-activation of PAK2 required both high- and low-affinity-CCK1-receptor-state activation. It was partially reduced by PKC- or Src-inhibition, but not with PI3K-inhibitors (wortmannin, LY294002) or thapsigargin. IPA-3, which prevents PAK2 binding to small-GTPases partially inhibited PAK2-activation, as well as reduced CCK-induced ERK1/2 activation and amylase release induced by CCK or bombesin. This study demonstrates pancreatic acini, possess only one Group-I-PAK, PAK2. CCK and other GI-hormones/neurotransmitters/growth-factors activate PAK2 via small GTPases (CDC42/Rac1), PKC and SFK but not cytosolic calcium or PI3K. CCK-activation of PAK2 showed several novel features being dependent on both receptor-activation states, having PLC- and PKC-dependent/independent components and small-GTPase-dependent/independent components. These results show that PAK2 is important in signaling cascades activated by numerous pancreatic stimuli which mediate their various physiological/pathophysiological responses and thus could be a promising target for the development of therapies in some pancreatic disorders such as pancreatitis.
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15
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Phosphorylation of LRRK2 by casein kinase 1α regulates trans-Golgi clustering via differential interaction with ARHGEF7. Nat Commun 2014; 5:5827. [PMID: 25500533 PMCID: PMC4268884 DOI: 10.1038/ncomms6827] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 11/10/2014] [Indexed: 12/29/2022] Open
Abstract
LRRK2, a gene relevant to Parkinson's disease, encodes a scaffolding protein with both GTPase and kinase activities. LRRK2 protein is itself phosphorylated and therefore subject to regulation by cell signaling but the kinase(s) responsible for this event have not been definitively identified. Here, using an unbiased siRNA kinome screen, we identify and validate casein kinase 1α (CK1α) as being responsible for LRRK2 phosphorylation, including in the adult mouse striatum. We further show that LRRK2 recruitment to TGN46-positive Golgi-derived vesicles is modulated by constitutive LRRK2 phosphorylation by CK1α. These effects are mediated by differential protein interactions of LRRK2 with a guanine nucleotide exchange factor, ARHGEF7. These pathways are therefore likely involved in the physiological maintenance of the Golgi in cells, which may play a role in the pathogenesis of Parkinson's disease.
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16
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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: 14] [Impact Index Per Article: 1.4] [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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17
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Sabbatini ME, Williams JA. Cholecystokinin-mediated RhoGDI phosphorylation via PKCα promotes both RhoA and Rac1 signaling. PLoS One 2013; 8:e66029. [PMID: 23776598 PMCID: PMC3679036 DOI: 10.1371/journal.pone.0066029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Accepted: 05/07/2013] [Indexed: 01/18/2023] Open
Abstract
RhoA and Rac1 have been implicated in the mechanism of CCK-induced amylase secretion from pancreatic acini. In all cell types studied to date, inactive Rho GTPases are present in the cytosol bound to the guanine nucleotide dissociation inhibitor RhoGDI. Here, we identified the switch mechanism regulating RhoGDI1-Rho GTPase dissociation and RhoA translocation upon CCK stimulation in pancreatic acini. We found that both Gα13 and PKC, independently, regulate CCK-induced RhoA translocation and that the PKC isoform involved is PKCα. Both RhoGDI1 and RhoGDI3, but not RhoGDI2, are expressed in pancreatic acini. Cytosolic RhoA and Rac1 are associated with RhoGDI1, and CCK-stimulated PKCα activation releases the complex. Overexpression of RhoGDI1, by binding RhoA, inhibits its activation, and thereby, CCK-induced apical amylase secretion. RhoA translocation is also inhibited by RhoGDI1. Inactive Rac1 influences CCK-induced RhoA activation by preventing RhoGDI1 from binding RhoA. By mutational analysis we found that CCK-induced PKCα phosphorylation on RhoGDI1 at Ser96 releases RhoA and Rac1 from RhoGDI1 to facilitate Rho GTPases signaling.
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Affiliation(s)
- Maria Eugenia Sabbatini
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America.
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18
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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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19
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Guo X, Wang M, Jiang J, Xie C, Peng F, Li X, Tian R, Qin R. Balanced Tiam1-rac1 and RhoA drives proliferation and invasion of pancreatic cancer cells. Mol Cancer Res 2013; 11:230-9. [PMID: 23322732 DOI: 10.1158/1541-7786.mcr-12-0632] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Tiam1 is a rac1-specific guanine nucleotide exchange factor, and Tiam1-rac1 is involved in a number of cellular processes. Rac1 and RhoA act as molecular switches that cycle between GTP- and GDP-bound states to balance the activities of rac1 and RhoA. The downregulation of rac1 activity leads to upregulation of RhoA activity, which promotes invasion and migration of pancreatic cancers cells. At present, however, the role of Tiam1-rac1 and RhoA in pancreatic cancers is not fully understood. We found that Tiam1 was upregulated in pancreatic cancers and was significantly expressed in tumors without lymph node involvement or distant metastasis compared with cancers where there was involvement. Although Tiam1-rac1 signaling promoted pancreatic cancer cell proliferation and tumor growth via the Wnt signaling pathway in vitro and in vivo, inhibiting Tiam1-rac1 signaling did not prolong the overall survival time in vivo. This provided evidence that there was a balance between rac1 and RhoA activities in pancreatic cancers. Furthermore, only the combined inhibition of Tiam1-rac1 and RhoA had a beneficial effect on the growth of pancreatic cancers in vivo. Taken together, these results suggest that the progression of pancreatic tumors is partially controlled by the balance between Tiam1-rac1 and RhoA.
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Affiliation(s)
- Xingjun Guo
- Department of Biliary-Pancreatic Surgery, Affiliated Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan City, Hubei Province, PR China
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20
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Multiple roles for the actin cytoskeleton during regulated exocytosis. Cell Mol Life Sci 2012; 70:2099-121. [PMID: 22986507 DOI: 10.1007/s00018-012-1156-5] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/28/2012] [Accepted: 08/30/2012] [Indexed: 01/01/2023]
Abstract
Regulated exocytosis is the main mechanism utilized by specialized secretory cells to deliver molecules to the cell surface by virtue of membranous containers (i.e., secretory vesicles). The process involves a series of highly coordinated and sequential steps, which include the biogenesis of the vesicles, their delivery to the cell periphery, their fusion with the plasma membrane, and the release of their content into the extracellular space. Each of these steps is regulated by the actin cytoskeleton. In this review, we summarize the current knowledge regarding the involvement of actin and its associated molecules during each of the exocytic steps in vertebrates, and suggest that the overall role of the actin cytoskeleton during regulated exocytosis is linked to the architecture and the physiology of the secretory cells under examination. Specifically, in neurons, neuroendocrine, endocrine, and hematopoietic cells, which contain small secretory vesicles that undergo rapid exocytosis (on the order of milliseconds), the actin cytoskeleton plays a role in pre-fusion events, where it acts primarily as a functional barrier and facilitates docking. In exocrine and other secretory cells, which contain large secretory vesicles that undergo slow exocytosis (seconds to minutes), the actin cytoskeleton plays a role in post-fusion events, where it regulates the dynamics of the fusion pore, facilitates the integration of the vesicles into the plasma membrane, provides structural support, and promotes the expulsion of large cargo molecules.
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21
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Abstract
A brief overview on the physiology and regulation of digestive enzyme secretion by the exocrine pancreas is presented. Knowledge about the physiology of the exocrine pancreas should help for a better understanding of the pathophysiology of both acute and chronic pancreatitis. In the pathophysiology of acute pancreatitis, fusion of zymogen granules with lysosomes, which leads to intracellular activation of trypsinogen, is still regarded as a key step in pathophysiology. The role of activation by cathepsins and the role of autoactivation of trypsinogen are still under debate. Studies on genetic alterations in various forms of human chronic pancreatitis can be interpreted that an imbalance between protease inhibitors and active proteases plays a key role. Toxic Ca(2+) signals by excessive liberation from the endoplasmic reticulum may play another role. The mortality of necrotizing pancreatitis is still high. Early mortality is caused by a systemic inflammatory response syndrome with or without concomitant infection of necrosis; late mortality by multi-organ failure syndrome due to sepsis. Therapy of necroses should be performed as late as possible. A step-up approach using CT-guided and/or transgastric endoscopic necrosectomy seems to be superior to a primary surgical approach. A brief overview of the German S3 guidelines, not yet published, regarding diagnosis and treatment of chronic pancreatitis is presented.
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Affiliation(s)
- Joachim Mössner
- Division of Gastroenterology and Rheumatology, Department of Medicine, Neurology and Dermatology, University Hospital Leipzig, Leipzig, Germany.
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22
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Abstract
PURPOSE OF REVIEW This review presents recent advancements in the mechanisms by which integrated signaling mechanisms elicit and regulate pancreatic endocrine and exocrine secretion. RECENT FINDINGS Cholecystokinin (CCK) can stimulate exocrine secretion by acting directly on neurons located in the dorsal motor of the vagus or indirectly by acting on pancreatic stellate cells. The importance of small GTPases such as RhoA and Rac1 in CCK-induced pancreatic secretion is also described. Ghrelin attenuates insulin secretion through the AMP-activated protein kinase-uncoupling protein 2 pathway. An exciting new report describes that leptin can influence insulin release by osteoclastin, a hormone produced by osteoblasts. This finding adds a new layer of complexity in the regulation of insulin secretion with implications for glucose and energy homeostasis. In addition, leptin also mediates insulin secretion through the sympathetic system and via pro-opiomelanocortin neurons, which could serve as the cross-road for leptin and melanocortin signaling pathways. Recent reports on the action of numerous other regulators such as atrial natriuretic peptide, neurotensin, and orexin B are also discussed. SUMMARY The pancreas is an extremely complex gland. Elucidation of the secretory and regulatory pathways that control pancreatic secretion will aid in the development of treatment for diseases such as pancreatitis, diabetes, and obesity.
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23
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Current world literature. Curr Opin Endocrinol Diabetes Obes 2011; 18:83-98. [PMID: 21178692 DOI: 10.1097/med.0b013e3283432fa7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ethanol impairs the assembly and disassembly of actin cytoskeleton and cell adhesion via the RhoA signaling pathway, catenin p120 and E-cadherin in CCK-stimulated pancreatic acini. Biochem Biophys Res Commun 2011; 405:558-63. [PMID: 21262198 DOI: 10.1016/j.bbrc.2011.01.067] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Accepted: 01/19/2011] [Indexed: 11/23/2022]
Abstract
The purpose of the present study was to evaluate the effects of EtOH on RhoA, actin cytoskeleton, catenin p120 and E-cadherin and their interactions in CCK-stimulated rat pancreatic acini. In isolated rat pancreatic acinar cells, CCK stimulation enhanced protein expression and association of RhoA, G(α13), Vav-2, catenin p120 and E-cadherin. CCK induced translocation and activation of RhoA and actin-filamentous assembly and disassembly. RhoA was diffusely localized throughout the acinar cell in the resting state and redistributed to the apical site in response to submaximal CCK stimulation and to a lesser extent in response to supramaximal CCK stimulation. Ethanol and subsequent submaximal CCK stimulation mimicked the effect of supramaximal CCK stimulation in terms of amylase secretion and morphologic effects. However, inhibition of RhoA translocation and activation were observed only with ethanol pretreatment. Ethanol followed by supramaximal CCK stimulation disrupted the well-defined localization of catenin p120 and E-cadherin around the lateral plasma membrane. These data suggest that ethanol impaired the assembly and disassembly of actin cytoskeleton and impaired cell-cell adhesion via the RhoA signaling pathways, catenin p120 and E-cadherin in CCK-stimulated pancreatic acini.
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Abstract
PURPOSE OF REVIEW This review identifies and puts into context the recent articles which have advanced understanding of the functions of pancreatic acinar cells and the mechanisms by which these functions are regulated. RECENT FINDINGS Receptors present on acinar cells, particularly those for cholecystokinin and secretin, have been better characterized as to the molecular nature of the ligand-receptor interaction. Other reports have described the potential regulation of acinar cells by GLP-1 and cannabinoids. Intracellular Ca2+ signaling remains at the center of stimulus secretion coupling and its regulation has been further defined. Recent studies have identified specific channels mediating Ca2+ release from intracellular stores and influx across the plasma membrane. Work downstream of intracellular mediators has focused on molecular mechanisms of exocytosis particularly involving small G proteins, SNARE proteins and chaperone molecules. In addition to secretion, recent studies have further defined the regulation of pancreatic growth both in adaptive regulation to diet and hormones in the regeneration that occurs after pancreatic damage. Lineage tracing has been used to show the contribution of different cell types. The importance of specific amino acids as signaling molecules to activate the mTOR pathway is being elucidated. SUMMARY Understanding the mechanisms that regulate pancreatic acinar cell function is contributing to knowledge of normal pancreatic function and alterations in disease.
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Sassmann A, Gier B, Gröne HJ, Drews G, Offermanns S, Wettschureck N. The Gq/G11-mediated signaling pathway is critical for autocrine potentiation of insulin secretion in mice. J Clin Invest 2010; 120:2184-93. [PMID: 20440069 DOI: 10.1172/jci41541] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 03/03/2010] [Indexed: 11/17/2022] Open
Abstract
A variety of neurotransmitters, gastrointestinal hormones, and metabolic signals are known to potentiate insulin secretion through GPCRs. We show here that beta cell-specific inactivation of the genes encoding the G protein alpha-subunits Galphaq and Galpha11 resulted in impaired glucose tolerance and insulin secretion in mice. Interestingly, the defects observed in Galphaq/Galpha11-deficient beta cells were not restricted to loss of muscarinic or metabolic potentiation of insulin release; the response to glucose per se was also diminished. Electrophysiological recordings revealed that glucose-induced depolarization of isolated beta cells was impaired in the absence of Galphaq/Galpha11, and closure of KATP channels was inhibited. We provide evidence that this reduced excitability was due to a loss of beta cell-autonomous potentiation of insulin secretion through factors cosecreted with insulin. We identified as autocrine mediators involved in this process extracellular nucleotides such as uridine diphosphate acting through the Gq/G11-coupled P2Y6 receptor and extracellular calcium acting through the calcium-sensing receptor. Thus, the Gq/G11-mediated signaling pathway potentiates insulin secretion in response to glucose by integrating systemic as well as autocrine/paracrine mediators.
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Affiliation(s)
- Antonia Sassmann
- Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Bad Nauheim, Germany
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