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Harvey KE, Tang S, LaVigne EK, Pratt EPS, Hockerman GH. RyR2 regulates store-operated Ca2+ entry, phospholipase C activity, and electrical excitability in the insulinoma cell line INS-1. PLoS One 2023; 18:e0285316. [PMID: 37141277 PMCID: PMC10159205 DOI: 10.1371/journal.pone.0285316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 04/19/2023] [Indexed: 05/05/2023] Open
Abstract
The ER Ca2+ channel ryanodine receptor 2 (RyR2) is required for maintenance of insulin content and glucose-stimulated insulin secretion, in part, via regulation of the protein IRBIT in the insulinoma cell line INS-1. Here, we examined store-operated and depolarization-dependent Ca2+entry using INS-1 cells in which either RyR2 or IRBIT were deleted. Store-operated Ca2+ entry (SOCE) stimulated with thapsigargin was reduced in RyR2KO cells compared to controls, but was unchanged in IRBITKO cells. STIM1 protein levels were not different between the three cell lines. Basal and stimulated (500 μM carbachol) phospholipase C (PLC) activity was also reduced specifically in RyR2KO cells. Insulin secretion stimulated by tolbutamide was reduced in RyR2KO and IRBITKO cells compared to controls, but was potentiated by an EPAC-selective cAMP analog in all three cell lines. Cellular PIP2 levels were increased and cortical f-actin levels were reduced in RyR2KO cells compared to controls. Whole-cell Cav channel current density was increased in RyR2KO cells compared to controls, and barium current was reduced by acute activation of the lipid phosphatase pseudojanin preferentially in RyR2KO cells over control INS-1 cells. Action potentials stimulated by 18 mM glucose were more frequent in RyR2KO cells compared to controls, and insensitive to the SK channel inhibitor apamin. Taken together, these results suggest that RyR2 plays a critical role in regulating PLC activity and PIP2 levels via regulation of SOCE. RyR2 also regulates β-cell electrical activity by controlling Cav current density and SK channel activation.
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Affiliation(s)
- Kyle E Harvey
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
| | - Shiqi Tang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
| | - Emily K LaVigne
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Interdisciplinary Life Sciences Program, Purdue University, West Lafayette, Indiana, United States of America
| | - Evan P S Pratt
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Interdisciplinary Life Sciences Program, Purdue University, West Lafayette, Indiana, United States of America
| | - Gregory H Hockerman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America
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Harvey KE, LaVigne EK, Dar MS, Salyer AE, Pratt EPS, Sample PA, Aryal UK, Gowher H, Hockerman GH. RyR2/IRBIT regulates insulin gene transcript, insulin content, and secretion in the insulinoma cell line INS-1. Sci Rep 2022; 12:7713. [PMID: 35562179 PMCID: PMC9095623 DOI: 10.1038/s41598-022-11276-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 03/31/2022] [Indexed: 12/01/2022] Open
Abstract
The role of ER Ca2+ release via ryanodine receptors (RyR) in pancreatic β-cell function is not well defined. Deletion of RyR2 from the rat insulinoma INS-1 (RyR2KO) enhanced IP3 receptor activity stimulated by 7.5 mM glucose, coincident with reduced levels of the protein IP3 Receptor Binding protein released with Inositol 1,4,5 Trisphosphate (IRBIT). Insulin content, basal (2.5 mM glucose) and 7.5 mM glucose-stimulated insulin secretion were reduced in RyR2KO and IRBITKO cells compared to controls. INS2 mRNA levels were reduced in both RyR2KO and IRBITKO cells, but INS1 mRNA levels were specifically decreased in RyR2KO cells. Nuclear localization of S-adenosylhomocysteinase (AHCY) was increased in RyR2KO and IRBITKO cells. DNA methylation of the INS1 and INS2 gene promotor regions was very low, and not different among RyR2KO, IRBITKO, and controls, but exon 2 of the INS1 and INS2 genes was more extensively methylated in RyR2KO and IRBITKO cells. Exploratory proteomic analysis revealed that deletion of RyR2 or IRBIT resulted in differential regulation of 314 and 137 proteins, respectively, with 41 in common. These results suggest that RyR2 regulates IRBIT levels and activity in INS-1 cells, and together maintain insulin content and secretion, and regulate the proteome, perhaps via DNA methylation.
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Affiliation(s)
- Kyle E Harvey
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Emily K LaVigne
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
- Interdisciplinary Life Sciences Program, Purdue University, West Lafayette, IN, USA
| | - Mohd Saleem Dar
- Department of Biochemistry, Purdue University, West Lafayette, IN, USA
| | - Amy E Salyer
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Evan P S Pratt
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
- Interdisciplinary Life Sciences Program, Purdue University, West Lafayette, IN, USA
| | - Paxton A Sample
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Uma K Aryal
- Proteomics Facility, Bindley Bioscience Center, Purdue University, West Lafayette, IN, USA
| | - Humaira Gowher
- Department of Biochemistry, 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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Velasco M, Díaz-García CM, Larqué C, Hiriart M. Modulation of Ionic Channels and Insulin Secretion by Drugs and Hormones in Pancreatic Beta Cells. Mol Pharmacol 2016; 90:341-57. [PMID: 27436126 DOI: 10.1124/mol.116.103861] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 07/18/2016] [Indexed: 12/11/2022] Open
Abstract
Pancreatic beta cells, unique cells that secrete insulin in response to an increase in glucose levels, play a significant role in glucose homeostasis. Glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells has been extensively explored. In this mechanism, glucose enters the cells and subsequently the metabolic cycle. During this process, the ATP/ADP ratio increases, leading to ATP-sensitive potassium (KATP) channel closure, which initiates depolarization that is also dependent on the activity of TRP nonselective ion channels. Depolarization leads to the opening of voltage-gated Na(+) channels (Nav) and subsequently voltage-dependent Ca(2+) channels (Cav). The increase in intracellular Ca(2+) triggers the exocytosis of insulin-containing vesicles. Thus, electrical activity of pancreatic beta cells plays a central role in GSIS. Moreover, many growth factors, incretins, neurotransmitters, and hormones can modulate GSIS, and the channels that participate in GSIS are highly regulated. In this review, we focus on the principal ionic channels (KATP, Nav, and Cav channels) involved in GSIS and how classic and new proteins, hormones, and drugs regulate it. Moreover, we also discuss advances on how metabolic disorders such as metabolic syndrome and diabetes mellitus change channel activity leading to changes in insulin secretion.
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Affiliation(s)
- Myrian Velasco
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Manlio Díaz-García
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Larqué
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Marcia Hiriart
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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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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Calcium modulation of exocytosis-linked plasma membrane potential oscillations in INS-1 832/13 cells. Biochem J 2015; 471:111-22. [DOI: 10.1042/bj20150616] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/04/2015] [Indexed: 01/17/2023]
Abstract
Oscillations in plasma membrane potential initiated by substrate-dependent blockade of ATP-sensitive K+ channels in insulin-secreting INS-1 832/13 are differentially linked to distinct voltage-activated Ca2+ channels and drive exocytosis. Ca2+ feeds back to control oscillation frequency, amplitude and prevalence.
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