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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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2
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Sunilkumar S, Ford SM. Elevated glucose concentration in culture media decreases membrane trafficking of SGLT2 in LLC-PK 1 cells via a cAMP/PKA-dependent pathway. Am J Physiol Cell Physiol 2019; 316:C913-C924. [PMID: 30943059 DOI: 10.1152/ajpcell.00433.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Na+-dependent glucose reabsorption in the renal proximal tubule is dynamically regulated by changes in blood glucose levels. There is, however, a disparity in reports studying the relationship between hyperglycemia and Na+-glucose-linked transporter (SGLT) function and expression. Similarly, manipulation of the glucose content in growth media of cultured renal cells has been shown to influence SGLT activity. In this investigation, SGLT activity was significantly lower in proximal tubule LLC-PK1 cells cultured in medium containing 17.5 than 5 mM glucose. α-Methyl d-glucopyranoside (AMG) transport kinetics showed reduced apparent Vmax and Km in cells grown in 17.5 mM glucose. SGLT2 was identified as the isoform responsible for glucose transport, and protein expression analyses showed decreased apical membrane localization of SGLT2 in cells grown in 17.5 mM glucose, explaining the reduced activity. Multiple signaling pathways have been implicated in regulation of SGLT activity and trafficking. Elevated media glucose decreased intracellular cAMP and PKA activation, leading to decreased SGLT2 trafficking into the plasma membrane, which was reversed after treatment with 1 µM forskolin. The effects of media glucose on SGLT activity were found to be dependent on p38 MAPK activation due to PKA-mediated signaling. Glucose-modulated AMG uptake is reversible and was associated with altered SGLT2 membrane trafficking and cAMP alterations. In summary, elevated glucose concentrations in culture medium decrease SGLT activity in LLC-PK1 cells by reducing membrane trafficking of SGLT2 via decreasing intracellular cAMP, resulting in a lowered PKA-dependent phosphorylation of p38 MAPK.
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Affiliation(s)
| | - Sue M Ford
- Department of Pharmaceutical Sciences, St. John's University , Queens, New York
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3
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Kong X, Li B, Deng Y, Ma X. FXR Mediates Adenylyl Cyclase 8 Expression in Pancreatic β-Cells. J Diabetes Res 2019; 2019:8915818. [PMID: 31485455 PMCID: PMC6710725 DOI: 10.1155/2019/8915818] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 04/30/2019] [Accepted: 06/29/2019] [Indexed: 02/03/2023] Open
Abstract
Adenylyl cyclase 8 (ADCY8) and Farnesoid X Receptor (FXR) have been identified in pancreatic β-cells and play important roles in insulin secretion. But the mechanisms underlying with respect to the regulation of ADCY8 expression in β-cells, particularly whether FXR is involved, remain unexplored. We now show that ADCY8 expression is decreased in Goto-Kakizaki (GK) rat islets compared with healthy Wistar controls. We also found that reduced ADCY8 is associated with decreased expression of FXR. Consistently, ADCY8 expression was suppressed by the knockdown of FXR in INS-1 832/13 cells, as well as the islets from FXR knockout mice. On the contrary, ADCY8 expression was increased in FXR-overexpressed INS-1 832/13 cells or in the case of FXR activation. Mechanistically, FXR directly binds to Adcy8 promoter and recruits the histone acetyltransferase Steroid Receptor Coactivator 1 (SRC1), thereby resulting in the increased acetylation of histone H3 in Adcy8 locus, promoting Adcy8 gene transcription in β-cells. Thus, this study indicates that FXR is a critical transcription factor that mediates ADCY8 expression in pancreatic β-cells and has characterized the chromatin modification associated with Adcy8 transcription.
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MESH Headings
- Adenylyl Cyclases/genetics
- Adenylyl Cyclases/metabolism
- Animals
- Cells, Cultured
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Gene Expression Regulation, Enzymologic
- Insulin-Secreting Cells/metabolism
- Insulin-Secreting Cells/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Rats
- Rats, Wistar
- Rats, Zucker
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
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Affiliation(s)
- Xiangchen Kong
- Shenzhen University Diabetes Institute, School of Medicine, Shenzhen University, Shenzhen 518060, China
| | - Bingfeng Li
- Shenzhen University Diabetes Institute, School of Medicine, Shenzhen University, Shenzhen 518060, China
| | - Yushen Deng
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Xiaosong Ma
- Shenzhen University Diabetes Institute, School of Medicine, Shenzhen University, Shenzhen 518060, China
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4
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Jiang WJ, Peng YC, Yang KM. Cellular signaling pathways regulating β-cell proliferation as a promising therapeutic target in the treatment of diabetes. Exp Ther Med 2018; 16:3275-3285. [PMID: 30233674 PMCID: PMC6143874 DOI: 10.3892/etm.2018.6603] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 07/27/2018] [Indexed: 12/30/2022] Open
Abstract
It is established that a decrease in β-cell number and deficiency in the function of existing β-cells contribute to type 1 and type 2 diabetes mellitus. Therefore, a major focus of current research is to identify novel methods of improving the number and function of β-cells, so as to prevent and/or postpone the development of diabetes mellitus and potentially reverse diabetes mellitus. Based on prior knowledge of the above-mentioned causes, promising therapeutic approaches may include direct transplantation of islets, implantation and subsequent induced differentiation of progenitors/stem cells to β-cells, replication of pre-existing β-cells, or activation of endogenous β-cell progenitors. More recently, with regards to cell replacement and regenerative treatment for diabetes patients, the identification of cellular signaling pathways with related genes or corresponding proteins involved in diabetes has become a topic of interest. However, the majority of pathways and molecules associated with β-cells remain unresolved, and the specialized functions of known pathways remain unclear, particularly in humans. The current article has evaluated the progress of research on pivotal cellular signaling pathways involved with β-cell proliferation and survival, and their validity for therapeutic adult β-cell regeneration in diabetes. More efforts are required to elucidate the cellular events involved in human β-cell proliferation in terms of the underlying mechanisms and functions.
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Affiliation(s)
- Wen-Juan Jiang
- Institute of Anatomy, Basic Medical College of Dali University, Dali, Yunnan 671000, P.R. China
| | - Yun-Chuan Peng
- Institute of Anatomy, Basic Medical College of Dali University, Dali, Yunnan 671000, P.R. China
| | - Kai-Ming Yang
- Institute of Anatomy, Basic Medical College of Dali University, Dali, Yunnan 671000, P.R. China
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5
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Lee CH, Chu CS, Tsai HJ, Ke LY, Lee HC, Yeh JL, Chen CH, Wu BN. Xanthine-derived KMUP-1 reverses glucotoxicity-activated Kv channels through the cAMP/PKA signaling pathway in rat pancreatic β cells. Chem Biol Interact 2017; 279:171-176. [PMID: 29183753 DOI: 10.1016/j.cbi.2017.11.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/23/2017] [Indexed: 10/18/2022]
Abstract
Hyperglycemia-associated glucotoxicity induces β-cell dysfunction and a reduction in insulin secretion. Voltage-dependent K+ (Kv) channels in pancreatic β-cells play a key role in glucose-dependent insulin secretion. KMUP-1, a xanthine derivative, has been demonstrated to modulate Kv channel activity in smooth muscles; however, the role of KMUP-1 in glucotoxicity-activated Kv channels in pancreatic β-cells remains unclear. In this study we examined the mechanisms by which KMUP-1 could inhibit high glucose (25 mM) activated Kv currents (IKv) in pancreatic β-cells. Pancreatic β-cells were isolated from Wistar rats and IKv was monitored by perforated patch-clamp recording. The peak IKv in high glucose-treated β-cells was ∼1.4-fold greater than for normal glucose (5.6 mM). KMUP-1 (1, 10, 30 μM) prevented high glucose-stimulated IKv in a concentration-dependent manner. Reduction of high glucose-activated IKv was also found for protein kinase A (PKA) activator 8-Br-cAMP (100 μM). Additionally, KMUP-1 (30 μM) current inhibition was reversed by the PKA inhibitor H-89 (1 μM). Otherwise, pretreatment with the PKC activator or inhibitor had no effect on IKv in high glucose exposure. In conclusion, glucotoxicity-diminished insulin secretion was due to IKv activation. KMUP-1 attenuated high glucose-stimulated IKv via the PKA but not the PKC signaling pathway. This finding provides evidence that KMUP-1 might be a promising agent for treating hyperglycemia-induced insulin resistance.
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Affiliation(s)
- Chien-Hsing Lee
- Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Chih-Sheng Chu
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan; Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Han-Jie Tsai
- Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Liang-Yin Ke
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan; Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Hsiang-Chun Lee
- Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan; Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Jwu-Lai Yeh
- Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan; Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
| | - Chu-Huang Chen
- Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan; Vascular and Medicinal Research, Texas Heart Institute, Houston, TX 77030, USA
| | - Bin-Nan Wu
- Department of Pharmacology, Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan; Lipid Science and Aging Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan; Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
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6
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Hastoy B, Clark A, Rorsman P, Lang J. Fusion pore in exocytosis: More than an exit gate? A β-cell perspective. Cell Calcium 2017; 68:45-61. [PMID: 29129207 DOI: 10.1016/j.ceca.2017.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/17/2017] [Accepted: 10/24/2017] [Indexed: 12/14/2022]
Abstract
Secretory vesicle exocytosis is a fundamental biological event and the process by which hormones (like insulin) are released into the blood. Considerable progress has been made in understanding this precisely orchestrated sequence of events from secretory vesicle docked at the cell membrane, hemifusion, to the opening of a membrane fusion pore. The exact biophysical and physiological regulation of these events implies a close interaction between membrane proteins and lipids in a confined space and constrained geometry to ensure appropriate delivery of cargo. We consider some of the still open questions such as the nature of the initiation of the fusion pore, the structure and the role of the Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (SNARE) transmembrane domains and their influence on the dynamics and regulation of exocytosis. We discuss how the membrane composition and protein-lipid interactions influence the likelihood of the nascent fusion pore forming. We relate these factors to the hypothesis that fusion pore expansion could be affected in type-2 diabetes via changes in disease-related gene transcription and alterations in the circulating lipid profile. Detailed characterisation of the dynamics of the fusion pore in vitro will contribute to understanding the larger issue of insulin secretory defects in diabetes.
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Affiliation(s)
- Benoit Hastoy
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK.
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, UK; Metabolic Research, Institute of Neuroscience and Physiology, University of Goteborg, Medicinaregatan 11, S-41309 Göteborg, Sweden
| | - Jochen Lang
- Laboratoire de Chimie et Biologie des Membranes et Nano-objets (CBMN), CNRS UMR 5248, Université de Bordeaux, Allée de Geoffrey St Hilaire, 33600 Pessac, France.
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7
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Urbano F, Filippello A, Di Pino A, Barbagallo D, Di Mauro S, Pappalardo A, Rabuazzo AM, Purrello M, Purrello F, Piro S. Altered expression of uncoupling protein 2 in GLP-1-producing cells after chronic high glucose exposure: implications for the pathogenesis of diabetes mellitus. Am J Physiol Cell Physiol 2016; 310:C558-67. [DOI: 10.1152/ajpcell.00148.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 01/06/2016] [Indexed: 01/11/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is a gut L-cell hormone that enhances glucose-stimulated insulin secretion. Several approaches that prevent GLP-1 degradation or activate the GLP-1 receptor are being used to treat type 2 diabetes mellitus (T2DM) patients. In T2DM, GLP-1 secretion has been suggested to be impaired, and this defect appears to be a consequence rather than a cause of impaired glucose homeostasis. However, although defective GLP-1 secretion has been correlated with insulin resistance, little is known about the direct effects of chronic high glucose concentrations, which are typical in diabetes patients, on GLP-1-secreting cell function. In the present study, we demonstrate that glucotoxicity directly affects GLP-1 secretion in GLUTag cells chronically exposed to high glucose. Our results indicate that this abnormality is associated with a decrease in ATP production due to the elevated expression of mitochondrial uncoupling protein 2 (UCP2). Furthermore, UCP2 inhibition using small interfering RNA (siRNA) and the application of glibenclamide, an ATP-sensitive potassium (KATP+) channel blocker, reverse the GLP-1 secretion defect induced by chronic high-glucose treatment. These results show that glucotoxicity diminishes the secretory responsiveness of GLP-1-secreting cells to acute glucose stimulation. We conclude that the loss of the incretin effect, as observed in T2DM patients, could at least partially depend on hyperglycemia, which is typical in diabetes patients. Such an understanding may not only provide new insight into diabetes complications but also ultimately contribute to the identification of novel molecular targets within intestinal L-cells for controlling and improving endogenous GLP-1 secretion.
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Affiliation(s)
- Francesca Urbano
- Department of Clinical and Experimental Medicine, Garibaldi-Nesima Hospital, University of Catania, Catania, Italy; and
| | - Agnese Filippello
- Department of Clinical and Experimental Medicine, Garibaldi-Nesima Hospital, University of Catania, Catania, Italy; and
| | - Antonino Di Pino
- Department of Clinical and Experimental Medicine, Garibaldi-Nesima Hospital, University of Catania, Catania, Italy; and
| | - Davide Barbagallo
- Department of BioMedical Sciences and BioTechnology, section of Biology and Genetics Giovanni Sichel, Unit of Molecular, Genome and Complex Systems BioMedicine, University of Catania, Catania, Italy
| | - Stefania Di Mauro
- Department of Clinical and Experimental Medicine, Garibaldi-Nesima Hospital, University of Catania, Catania, Italy; and
| | - Alessandro Pappalardo
- Department of Clinical and Experimental Medicine, Garibaldi-Nesima Hospital, University of Catania, Catania, Italy; and
| | - Agata Maria Rabuazzo
- Department of Clinical and Experimental Medicine, Garibaldi-Nesima Hospital, University of Catania, Catania, Italy; and
| | - Michele Purrello
- Department of BioMedical Sciences and BioTechnology, section of Biology and Genetics Giovanni Sichel, Unit of Molecular, Genome and Complex Systems BioMedicine, University of Catania, Catania, Italy
| | - Francesco Purrello
- Department of Clinical and Experimental Medicine, Garibaldi-Nesima Hospital, University of Catania, Catania, Italy; and
| | - Salvatore Piro
- Department of Clinical and Experimental Medicine, Garibaldi-Nesima Hospital, University of Catania, Catania, Italy; and
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8
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Pratt EPS, Salyer AE, Guerra ML, Hockerman GH. Ca2+ influx through L-type Ca2+ channels and Ca2+-induced Ca2+ release regulate cAMP accumulation and Epac1-dependent ERK 1/2 activation in INS-1 cells. Mol Cell Endocrinol 2016; 419:60-71. [PMID: 26435461 PMCID: PMC4684454 DOI: 10.1016/j.mce.2015.09.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/28/2015] [Accepted: 09/29/2015] [Indexed: 02/09/2023]
Abstract
We previously reported that INS-1 cells expressing the intracellular II-III loop of the L-type Ca(2+) channel Cav1.2 (Cav1.2/II-III cells) are deficient in Ca(2+)-induced Ca(2+) release (CICR). Here we show that glucose-stimulated ERK 1/2 phosphorylation (GSEP) is slowed and reduced in Cav1.2/II-III cells compared to INS-1 cells. This parallels a decrease in glucose-stimulated cAMP accumulation (GS-cAMP) in Cav1.2/II-III cells. Influx of Ca(2+) via L-type Ca(2+) channels and CICR play roles in both GSEP and GS-cAMP in INS-1 cells since both are inhibited by nicardipine or ryanodine. Further, the Epac1-selective inhibitor CE3F4 abolishes glucose-stimulated ERK activation in INS-1 cells, as measured using the FRET-based sensor EKAR. The non-selective Epac antagonist ESI-09 but not the Epac2-selective antagonist ESI-05 nor the PKA antagonist Rp-cAMPs inhibits GSEP in both INS-1 and Cav1.2/II-III cells. We conclude that L-type Ca(2+) channel-dependent cAMP accumulation, that's amplified by CICR, activates Epac1 and drives GSEP in INS-1 cells.
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Affiliation(s)
- Evan P S Pratt
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA; Purdue University Life Sciences Graduate Program, Purdue University, West Lafayette, IN, USA
| | - Amy E Salyer
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Marcy L Guerra
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Gregory H Hockerman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA.
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