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Joseph SK, Young MP, Alzayady K, Yule DI, Ali M, Booth DM, Hajnóczky G. Redox regulation of type-I inositol trisphosphate receptors in intact mammalian cells. J Biol Chem 2018; 293:17464-17476. [PMID: 30228182 DOI: 10.1074/jbc.ra118.005624] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/09/2018] [Indexed: 12/31/2022] Open
Abstract
A sensitization of inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ release is associated with oxidative stress in multiple cell types. These effects are thought to be mediated by alterations in the redox state of critical thiols in the IP3R, but this has not been directly demonstrated in intact cells. Here, we utilized a combination of gel-shift assays with MPEG-maleimides and LC-MS/MS to monitor the redox state of recombinant IP3R1 expressed in HEK293 cells. We found that under basal conditions, ∼5 of the 60 cysteines are oxidized in IP3R1. Cell treatment with 50 μm thimerosal altered gel shifts, indicating oxidation of ∼20 cysteines. By contrast, the shifts induced by 0.5 mm H2O2 or other oxidants were much smaller. Monitoring of biotin-maleimide attachment to IP3R1 by LC-MS/MS with 71% coverage of the receptor sequence revealed modification of two cytosolic (Cys-292 and Cys-1415) and two intraluminal cysteines (Cys-2496 and Cys-2533) under basal conditions. The thimerosal treatment modified an additional eleven cysteines, but only three (Cys-206, Cys-767, and Cys-1459) were consistently oxidized in multiple experiments. H2O2 also oxidized Cys-206 and additionally oxidized two residues not modified by thimerosal (Cys-214 and Cys-1397). Potentiation of IP3R channel function by oxidants was measured with cysteine variants transfected into a HEK293 IP3R triple-knockout cell line, indicating that the functionally relevant redox-sensitive cysteines are predominantly clustered within the N-terminal suppressor domain of IP3R. To our knowledge, this study is the first that has used proteomic methods to assess the redox state of individual thiols in IP3R in intact cells.
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Affiliation(s)
- Suresh K Joseph
- From the MitoCare Center, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107,
| | - Michael P Young
- From the MitoCare Center, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Kamil Alzayady
- the Department of Pharmacology & Physiology, University of Rochester, Rochester, New York 14642, and
| | - David I Yule
- the Department of Pharmacology & Physiology, University of Rochester, Rochester, New York 14642, and
| | - Mehboob Ali
- the Center for Perinatal Research, Research Institute, Nationwide Children's Hospital, Columbus, Ohio 43205
| | - David M Booth
- From the MitoCare Center, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - György Hajnóczky
- From the MitoCare Center, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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Intermittent hypoxia-generated ROS contributes to intracellular zinc regulation that limits ischemia/reperfusion injury in adult rat cardiomyocyte. J Mol Cell Cardiol 2018; 118:122-132. [PMID: 29577873 DOI: 10.1016/j.yjmcc.2018.03.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 03/05/2018] [Accepted: 03/21/2018] [Indexed: 12/20/2022]
Abstract
Intermittent hypoxia (IH) has been shown to exert cardioprotective effects against ischemia/reperfusion (I/R) injury through the preservation of ion homeostasis. I/R dramatically elevated cytosolic Zn2+ and caused cardiomyocyte death. However, the role of IH exposure in the relationship between Zn2+ regulation and cardioprotection is still unclear. The aim of the present study was to study whether IH exposure could help in intracellular Zn2+ regulation, hence contributing to cardioprotection against I/R injury. Adult rat cardiomyocytes were exposed to IH (5% O2, 5% CO2 and balanced N2) for 30 min followed by 30 min of normoxia (21% O2, 5% CO2 and balanced N2). Changes in intracellular Zn2+ concentration were determined using a Zn2+-specific fluorescent dye, FluoZin-3 or RhodZin-3. Fluorescence was monitored under an inverted fluorescent or confocal microscope. The results demonstrated that I/R or 2,2'-dithiodipyridine (DTDP), a reactive disulphide compound, induced Zn2+ release from metallothioneins (MTs), subsequently causing cytosolic Zn2+ overload, which in turn increased intracellular Zn2+ entry into the mitochondria via a Ca2+ uniporter, hence inducing mitochondrial membrane potential loss, and eventually led to cell death. However, the cytosolic Zn2+ overload and cell death caused by I/R or DTDP was significantly reduced by treatment of cardiomyocytes with IH. The findings from this study suggest that IH might exert its cardioprotective effect through reducing the I/R-induced cytosolic Zn2+ overload and cell death in cardiomyocytes.
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3
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Gökce H, Bahçeli S. FT-IR, micro-Raman and UV-vis spectroscopic and quantum chemical investigations of free 2,2'-dithiodipyridine and its metal (Co, Cu and Zn) halide complexes. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 114:61-73. [PMID: 23751221 DOI: 10.1016/j.saa.2013.04.112] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/16/2013] [Accepted: 04/24/2013] [Indexed: 06/02/2023]
Abstract
In this study the elemental analysis results, molecular geometries, vibrational and electronic absorption spectra of free 2,2'-dithiodipyridine(C10H8N2S2), (or DTDP) (with synonym, 2,2'-dipyridyl disulfide) and M(C10H8N2S2)Cl2 (M=Co, Cu and Zn) complexes have been reported. Vibrational wavenumbers of free DTDP and its metal halide complexes have been calculated by using DFT/B3LYP calculation method with 6-31++G(d,p) and Lanl2DZ basis sets, respectively, in the ground state, for the first time. The calculated fundamental vibrational frequencies are in a good agreement with experimental data. The HOMO, LUMO and MEP analyses of all compounds are performed by DFT method.
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Affiliation(s)
- Halil Gökce
- Vocational High School of Health Services, Giresun University, Güre Campus, 28200 Giresun, Turkey
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4
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Abstract
The importance of K(ATP) channels in stimulus-secretion coupling of β-cells is well established, although they are not indispensable for the maintenance of glycaemic control. This review article depicts a new role for K(ATP) channels by showing that genetic or pharmacological ablation of these channels protects β-cells against oxidative stress. Increased production of oxidants is a crucial factor in the pathogenesis of type 2 diabetes mellitus (T2DM). T2DM develops when β-cells can no longer compensate for the high demand of insulin resulting from excess fuel intake. Instead β-cells start to secrete less insulin and β-cell mass is diminished by apoptosis. Both, reduction of insulin secretion and β-cell mass induced by oxidative stress, are prevented by deletion or inhibition of K(ATP) channels. These findings may open up new insights into the early treatment of T2DM.
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Affiliation(s)
- G Drews
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany.
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5
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Massa F, Tormo A, Béraud-Dufour S, Coppola T, Mazella J. Neurotensin-induced Erk1/2 phosphorylation and growth of human colonic cancer cells are independent from growth factors receptors activation. Biochem Biophys Res Commun 2011; 414:118-22. [PMID: 21945442 DOI: 10.1016/j.bbrc.2011.09.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 09/07/2011] [Indexed: 10/17/2022]
Abstract
Neurotensin (NT) promotes the proliferation of human colonic cancer cells by undefined mechanisms. We already demonstrated that, in the human colon adenocarcinoma cell line HT29, the effects of NT were mediated by a complex formed between the NT receptor-1 (NTSR1) and-3 (NTSR3). Here we examined cellular mechanisms that led to NT-induced MAP kinase phosphorylation and growth factors receptors transactivation in colonic cancer cells and proliferation in HT29 cells. With the aim to identify upstream signaling involved in NT-elicited MAP kinase activation, we found that the stimulatory effects of the peptide were totally independent from the activation of the epidermal growth factor receptor (EGFR) both in the HT29 and the HCT116 cells. NT was unable to promote phosphorylation of EGFR and to compete with EGF for its binding to the receptor. Pharmacological approaches allowed us to differentiate EGF and NT signaling in HT29 cells since only NT activation of Erk1/2 was shown to be sensitive to PKC inhibitors and since only NT increased the intracellular level of calcium. We also observed that NT was not able to transactivate Insulin-like growth factor receptor. Our findings indicate that, in the HT29 and HCT116 cell lines, NT stimulates MAP kinase phosphorylation and cell growth by a pathway which does not involve EGF system but rather NT receptors which transduce their own intracellular effectors. These results indicate that depending on the cell line used, blocking EGFR is not the general rule to inhibit NT-induced cancer cell proliferation.
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Affiliation(s)
- Fabienne Massa
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice-Sophia Antipolis, CNRS UMR 6097, 660 route des Lucioles, 06560 Valbonne, France
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6
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Béraud-Dufour S, Abderrahmani A, Noel J, Brau F, Waeber G, Mazella J, Coppola T. Neurotensin is a regulator of insulin secretion in pancreatic beta-cells. Int J Biochem Cell Biol 2010; 42:1681-8. [DOI: 10.1016/j.biocel.2010.06.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 06/18/2010] [Accepted: 06/23/2010] [Indexed: 11/29/2022]
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7
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Joseph SK. Role of thiols in the structure and function of inositol trisphosphate receptors. CURRENT TOPICS IN MEMBRANES 2010; 66:299-322. [PMID: 22353485 DOI: 10.1016/s1063-5823(10)66013-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Drews G, Krippeit-Drews P, Düfer M. Oxidative stress and beta-cell dysfunction. Pflugers Arch 2010; 460:703-18. [PMID: 20652307 DOI: 10.1007/s00424-010-0862-9] [Citation(s) in RCA: 188] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 06/23/2010] [Accepted: 06/25/2010] [Indexed: 12/11/2022]
Abstract
Diabetes mellitus type 1 and 2 (T1DM and T2DM) are complex multifactorial diseases. Loss of beta-cell function caused by reduced secretory capacity and enhanced apoptosis is a key event in the pathogenesis of both diabetes types. Oxidative stress induced by reactive oxygen and nitrogen species is critically involved in the impairment of beta-cell function during the development of diabetes. Because of their low antioxidant capacity, beta-cells are extremely sensitive towards oxidative stress. In beta-cells, important targets for an oxidant insult are cell metabolism and K(ATP) channels. The oxidant-evoked alterations of K(ATP) channel activity seem to be critical for oxidant-induced dysfunction because genetic ablation of K(ATP) channels attenuates the effects of oxidative stress on beta-cell function. Besides the effects on metabolism, interference of oxidants with mitochondria induces key events in apoptosis. Consequently, increasing antioxidant defence is a promising strategy to delay beta cell failure in (pre)-diabetic patients or during islet transplantation. Knock-out of K(ATP) channels has beneficial effects on oxidant-induced inhibition of insulin secretion and cell death. Interestingly, these effects can be mimicked by sulfonylureas that have been used in the treatment of T2DM for many years. Loss of functional K(ATP) channels leads to up-regulation of antioxidant enzymes, a process that depends on cytosolic Ca(2+). These observations are of great importance for clinical intervention because they show a possibility to protect beta-cells at an early stage before dramatic changes of the secretory capacity and loss of cell mass become manifest and lead to glucose intolerance or even overt diabetes.
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Affiliation(s)
- Gisela Drews
- Department of Pharmacology and Clinical Pharmacy, University of Tübingen, Auf der Morgenstelle 8, Tübingen, Germany.
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9
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Rutter GA, Tsuboi T, Ravier MA. Ca2+ microdomains and the control of insulin secretion. Cell Calcium 2006; 40:539-51. [PMID: 17030367 DOI: 10.1016/j.ceca.2006.08.015] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Accepted: 08/23/2006] [Indexed: 11/19/2022]
Abstract
Nutrient-induced increases in intracellular free Ca(2+) concentrations are the key trigger for insulin release from pancreatic islet beta-cells. These Ca(2+) changes are tightly regulated temporally, occurring as Ca(2+) influx-dependent baseline oscillations. We explore here the concept that locally high [Ca(2+)] concentrations (i.e. Ca(2+) microdomains) may control exocytosis via the recruitment of key effector proteins to sites of exocytosis. Importantly, recent advances in the development of organelle- and membrane-targeted green fluorescent protein (GFP-) or aequorin-based Ca(2+) indicators, as well as in rapid imaging techniques, are providing new insights into the potential role of these Ca(2+) microdomains in beta-cells. We summarise here some of the evidence indicating that Ca(2+) microdomains beneath the plasma membrane and at the surface of large dense core vesicles may be important in the normal regulation of insulin secretion, and may conceivably contribute to "ATP-sensitive K(+)-channel independent" effects of glucose. We also discuss evidence that, in contrast to certain non-excitable cells, direct transfer of Ca(2+) from the ER to mitochondria via localised physical contacts between these organelles is relatively less important for efficient mitochondrial Ca(2+) uptake in beta-cells. Finally, we discuss evidence from single cell imaging that increases in cytosolic Ca(2+) are not required for the upstroke of oscillations in mitochondrial redox state, but may underlie the reoxidation process.
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Affiliation(s)
- Guy A Rutter
- Department of Cell Biology, Division of Medicine, Imperial College London, Sir Alexander Fleming Building, London, UK.
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Woolcott OO, Gustafsson AJ, Dzabic M, Pierro C, Tedeschi P, Sandgren J, Bari MR, Nguyen KH, Bianchi M, Rakonjac M, Rådmark O, Ostenson CG, Islam MS. Arachidonic acid is a physiological activator of the ryanodine receptor in pancreatic β-cells. Cell Calcium 2006; 39:529-37. [PMID: 16620964 DOI: 10.1016/j.ceca.2006.02.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Revised: 02/09/2006] [Accepted: 02/26/2006] [Indexed: 11/23/2022]
Abstract
Pancreatic beta-cells have ryanodine receptors but little is known about their physiological regulation. Previous studies have shown that arachidonic acid releases Ca(2+) from intracellular stores in beta-cells but the identity of the channels involved in the Ca(2+) release has not been elucidated. We studied the mechanism by which arachidonic acid induces Ca(2+) concentration changes in pancreatic beta-cells. Cytosolic free Ca(2+) concentration was measured in fura-2-loaded INS-1E cells and in primary beta-cells from Wistar rats. The increase of cytosolic Ca(2+) concentration induced by arachidonic acid (150microM) was due to both Ca(2+) release from intracellular stores and influx of Ca(2+) from extracellular medium. 5,8,11,14-Eicosatetraynoic acid, a non-metabolizable analogue of arachidonic acid, mimicked the effect of arachidonic acid, indicating that arachidonic acid itself mediated Ca(2+) increase. The Ca(2+) release induced by arachidonic acid was from the endoplasmic reticulum since it was blocked by thapsigargin. 2-Aminoethyl diphenylborinate (50microM), which is known to inhibit 1,4,5-inositol-triphosphate-receptors, did not block Ca(2+) release by arachidonic acid. However, ryanodine (100microM), a blocker of ryanodine receptors, abolished the effect of arachidonic acid on Ca(2+) release in both types of cells. These observations indicate that arachidonic acid is a physiological activator of ryanodine receptors in beta-cells.
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Affiliation(s)
- Orison O Woolcott
- Karolinska Institutet, Södersjukhuset, Department of Internal Medicine, Research Center, SE-118 83 Stockholm, Sweden.
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11
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Waring P. Redox active calcium ion channels and cell death. Arch Biochem Biophys 2005; 434:33-42. [PMID: 15629106 DOI: 10.1016/j.abb.2004.08.001] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Revised: 07/27/2004] [Indexed: 01/01/2023]
Abstract
Calcium plays a key role in both apoptotic and necrotic cell death. Emptying of intracellular calcium stores and/or alteration in intracellular calcium levels can modulate cell death in almost all cell types. These calcium fluxes are determined by the activity of membrane channels normally under tight control. The channels may be ligand activated or voltage dependent as well as being under the control of affector molecules such as calmodulin. It has become increasingly apparent that many calcium channels are affected by reactive oxygen or reactive nitrogen species; ROS/RNS. This may be part of the normal signaling pathways in the cell or by the action of exogenously generated ROS or RNS often by toxins. This review covers the recent literature on the activity of these redox active channels as related to cell death.
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Affiliation(s)
- Paul Waring
- Department of Chemistry, Centre for the Study of Bioactive Molecules, The Faculties, Australian National University, Acton, Canberra, ACT 0200, Australia.
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12
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Yu J, Leibiger B, Yang SN, Caffery JJ, Shears SB, Leibiger IB, Barker CJ, Berggren PO. Cytosolic multiple inositol polyphosphate phosphatase in the regulation of cytoplasmic free Ca2+ concentration. J Biol Chem 2003; 278:46210-8. [PMID: 12963730 DOI: 10.1074/jbc.m303743200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Multiple inositol polyphosphate phosphatase (MIPP) is an enzyme that, in vitro, has the interesting property of degrading higher inositol polyphosphates to the Ca2+ second messenger, inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), independently of inositol lipid breakdown. We hypothesized that a truncated cytosolic form of the largely endoplasmic reticulum-confined MIPP (cyt-MIPP) could represent an important new tool in the investigation of Ins(1,4,5)P3-dependent intracellular Ca2+ homeostasis. To optimize our ability to judge the impact of cyt-MIPP on intracellular Ca2+ concentration ([Ca2+]i) we chose a poorly responsive beta-cell line (HIT M2.2.2) with an abnormally low [Ca2+]i. Our results show for the first time in an intact mammalian cell that cyt-MIPP expression leads to a significant enhancement of Ins(1,4,5)P3 concentration. This is achieved without a significant interference from other cyt-MIPP-derived inositol phosphates. Furthermore, the low basal [Ca2+]i of these cells was raised to normal levels (35 to 115 nm) when they expressed cyt-MIPP. Noteworthy is that the normal feeble glucose-induced Ca2+ response of HIT M2.2.2 cells was enhanced dramatically by mechanisms related to this increase in basal [Ca2+]i. These data support the use of cyt-MIPP as an important tool in investigating Ins(1,4,5)P3-dependent Ca2+ homeostasis and suggest a close link between Ins(1,4,5)P3 concentration and basal [Ca2+]i, the latter being an important modulator of Ca2+ signaling in the pancreatic beta-cell.
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Affiliation(s)
- Jia Yu
- Department of Molecular Medicine, The Rolf Luft Center for Diabetes Research, L3, Karolinska Institutet, Karolinska Hospital, Stockholm SE-171 76, Sweden
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Kuo SY, Jiann BP, Lu YC, Chang HT, Chen WC, Huang JK, Jan CR. Thiol oxidation by 2,2'-dithiodipyridine induced calcium mobilization in MG63 human osteosarcoma cells. Life Sci 2003; 72:1733-43. [PMID: 12559394 DOI: 10.1016/s0024-3205(02)02479-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
2,2'-dithiodipyridine (2,2'-DTDP), a reactive disulphide that mobilizes Ca(2+) in muscle, induced an increase in cytoplasmic free Ca(2+)concentrations ([Ca(2+)](i)) in MG63 human osteosarcoma cells loaded with the Ca(2+)-sensitive dye fura-2. 2,2'-DTDP acted in a concentration-independent manner with an EC(50) of 50 microM. The Ca(2+) signal comprised an initial spike and a prolonged increase. Removing extracellular Ca(2+) did not alter the Ca(2+) signal, suggesting that the Ca(2+) signal was due to store Ca(2+) release. In Ca(2+)-free medium, the 2,2'-DTDP-induced [Ca(2+)](i) increase was not changed by depleting store Ca(2+) with 50 microM bredfeldin A (a Golgi apparatus permeabilizer), 2 microM carbonylcyanide m-chlorophenylhydrazone (CCCP, a mitochondrial uncoupler), 1 microM thapsigargin (an endoplasmic reticulum Ca(2+)pump inhibitor) or 5 microM ryanodine. Conversely, 2,2'-DTDP pretreatment abolished CCCP and thapsigargin-induced [Ca(2+)](i) increases. 2,2'-DTDP-induced Ca(2+) signals in Ca(2+)-containing medium were not affected by modulation of protein kinase C activity or suppression of phospholipase C activity. However, 2,2'-DTDP-induced Ca(2+) release was inhibited by a thiol-selective reducing reagent, dithiothreitol (5-25 microM) in a concentration-dependent manner. Collectively, this study shows that 2,2'-DTDP induced [Ca(2+)](i) increases in human osteosarcoma cells via releasing store Ca(2+)from multiple stores in a manner independent of protein kinase C or phospholipase C activity. The 2,2'-DTDP-induced store Ca(2+) release appeared to be dependent on oxidation of membranes.
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Affiliation(s)
- Soong-Yu Kuo
- Department of Medical Technology, Fooyin Institute of Technology, Kaohsiung 813, Taiwan
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14
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Abstract
The list of Ca(2+) channels involved in stimulus-secretion coupling in beta-cells is increasing. In this respect the roles of the voltage-gated Ca(2+) channels and IP(3) receptors are well accepted. There is a lack of consensus about the significance of a third group of Ca(2+) channels called ryanodine (RY) receptors. These are large conduits located on Ca(2+) storage organelle. Ca(2+) gates these channels in a concentration- and time-dependent manner. Activation of these channels by Ca(2+) leads to fast release of Ca(2+) from the stores, a process called Ca(2+)-induced Ca(2+) release (CICR). A substantial body of evidence confirms that beta-cells have RY receptors. CICR by RY receptors amplifies Ca(2+) signals. Some properties of RY receptors ensure that this amplification process is engaged in a context-dependent manner. Several endogenous molecules and processes that modulate RY receptors determine the appropriate context. Among these are several glycolytic intermediates, long-chain acyl CoA, ATP, cAMP, cADPR, NO, and high luminal Ca(2+) concentration, and all of these have been shown to sensitize RY receptors to the trigger action of Ca(2+). RY receptors, thus, detect co-incident signals and integrate them. These Ca(2+) channels are targets for the action of cAMP-linked incretin hormones that stimulate glucose-dependent insulin secretion. In beta-cells some RY receptors are located on the secretory vesicles. Thus, despite their low abundance, RY receptors are emerging as distinct players in beta-cell function by virtue of their large conductance, strategic locations, and their ability to amplify Ca(2+) signals in a context-dependent manner.
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Affiliation(s)
- Md Shahidul Islam
- Department of Molecular Medicine, Karolinska Institutet, Department of Endocrinology, Karolinska Hospital, Stockholm, Sweden.
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15
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Lemmens R, Larsson O, Berggren PO, Islam MS. Ca2+-induced Ca2+ release from the endoplasmic reticulum amplifies the Ca2+ signal mediated by activation of voltage-gated L-type Ca2+ channels in pancreatic beta-cells. J Biol Chem 2001; 276:9971-7. [PMID: 11139580 DOI: 10.1074/jbc.m009463200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stimulus-secretion coupling in pancreatic beta-cells involves membrane depolarization and Ca(2+) entry through voltage-gated L-type Ca(2+) channels, which is one determinant of increases in the cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)). We investigated how the endoplasmic reticulum (ER)-associated Ca(2+) apparatus further modifies this Ca(2+) signal. When fura-2-loaded mouse beta-cells were depolarized by KCl in the presence of 3 mm glucose, [Ca(2+)](i) increased to a peak in two phases. The second phase of the [Ca(2+)](i) increase was abolished when ER Ca(2+) stores were depleted by thapsigargin. The steady-state [Ca(2+)](i) measured at 300 s of depolarization was higher in control cells compared with cells in which the ER Ca(2+) pools were depleted. The amount of Ca(2+) presented to the cytoplasm during depolarization as estimated from the integral of the increment in [Ca(2+)](i) over time (integralDelta[Ca(2+)](i).dt) was approximately 30% higher compared with that in the Ca(2+) pool-depleted cells. neo-thapsigargin, an inactive analog, did not affect [Ca(2+)](i) response. Using Sr(2+) in the extracellular medium and exploiting the differences in the fluorescence properties of Ca(2+)- and Sr(2+)-bound fluo-3, we found that the incoming Sr(2+) triggered Ca(2+) release from the ER. Depolarization-induced [Ca(2+)](i) response was not altered by, an inhibitor of phosphatidylinositol-specific phospholipase C, suggesting that stimulation of the enzyme by Ca(2+) is not essential for amplification of Ca(2+) signaling. [Ca(2+)](i) response was enhanced when cells were depolarized in the presence of 3 mm glucose, forskolin, and caffeine, suggesting involvement of ryanodine receptors in the amplification process. Pretreatment with ryanodine (100 microm) diminished the second phase of the depolarization-induced increase in [Ca(2+)](i). We conclude that Ca(2+) entry through L-type voltage-gated Ca(2+) channels triggers Ca(2+) release from the ER and that such a process amplifies depolarization-induced Ca(2+) signaling in beta-cells.
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Affiliation(s)
- R Lemmens
- Rolf Luft Center for Diabetes Research, Department of Molecular Medicine, Endocrine and Diabetes Unit, Karolinska Institutet, Karolinska Hospital, S-171 76 Stockholm, Sweden
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16
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Holz GG, Leech CA, Heller RS, Castonguay M, Habener JF. cAMP-dependent mobilization of intracellular Ca2+ stores by activation of ryanodine receptors in pancreatic beta-cells. A Ca2+ signaling system stimulated by the insulinotropic hormone glucagon-like peptide-1-(7-37). J Biol Chem 1999; 274:14147-56. [PMID: 10318832 PMCID: PMC3508791 DOI: 10.1074/jbc.274.20.14147] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is an intestinally derived insulinotropic hormone currently under investigation for use as a novel therapeutic agent in the treatment of type 2 diabetes mellitus. In vitro studies of pancreatic islets of Langerhans demonstrated that GLP-1 interacts with specific beta-cell G protein-coupled receptors, thereby facilitating insulin exocytosis by raising intracellular levels of cAMP and Ca2+. Here we report that the stimulatory influence of GLP-1 on Ca2+ signaling results, in part, from cAMP-dependent mobilization of ryanodine-sensitive Ca2+ stores. Studies of human, rat, and mouse beta-cells demonstrate that the binding of a fluorescent derivative of ryanodine (BODIPY FL-X ryanodine) to its receptors is specific, reversible, and of high affinity. Rat islets and BTC3 insulinoma cells are shown by reverse transcriptase polymerase chain reaction analyses to express mRNA corresponding to the type 2 isoform of ryanodine receptor-intracellular Ca2+ release channel (RYR2). Single-cell measurements of [Ca2+]i using primary cultures of rat and human beta-cells indicate that GLP-1 facilitates Ca2+-induced Ca2+ release (CICR), whereby mobilization of Ca2+ stores is triggered by influx of Ca2+ through L-type Ca2+ channels. In these cells, GLP-1 is shown to interact with metabolism of D-glucose to produce a fast transient increase of [Ca2+]i. This effect is reproduced by 8-Br-cAMP, but is blocked by a GLP-1 receptor antagonist (exendin-(9-39)), a cAMP antagonist ((Rp)-cAMPS), an L-type Ca2+ channel antagonist (nimodipine), an antagonist of the sarco(endo)plasmic reticulum Ca2+ ATPase (thapsigargin), or by ryanodine. Characterization of the CICR mechanism by voltage clamp analysis also demonstrates a stimulation of Ca2+ release by caffeine. These findings provide new support for a model of beta-cell signal transduction whereby GLP-1 promotes CICR by sensitizing intracellular Ca2+ release channels to the stimulatory influence of cytosolic Ca2+.
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Affiliation(s)
- G G Holz
- Diabetes Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
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Törnquist K, Vainio P, Titievsky A, Dugué B, Tuominen R. Redox modulation of intracellular free calcium concentration in thyroid FRTL-5 cells: evidence for an enhanced extrusion of calcium. Biochem J 1999; 339 ( Pt 3):621-8. [PMID: 10215601 PMCID: PMC1220198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Redox modulation is involved in the regulation of the intracellular free calcium concentration ([Ca2+]i) in several cell types. In thyroid cells, including thyroid FRTL-5 cells, changes in [Ca2+]i regulate important functions. In the present study we investigated the effects of the oxidizing compounds thimerosal and t-butyl hydroperoxide on [Ca2+]i in thyroid FRTL-5 cells. Thimerosal mobilized sequestered calcium, and evoked modest store-dependent calcium entry. Both compounds potently attenuated the increase in [Ca2+]i when store-operated calcium entry was evoked with thapsigargin. The entry of barium was not attenuated. Experiments performed with high extracellular pH, in sodium-free buffer and in the presence of vanadate suggested that thimerosal decreased [Ca2+]i by activating a calcium extrusion mechanism, probably a plasma membrane Ca2+-ATPase. All the observed effects were abrogated by the reducing agent beta-mercaptoethanol. The mechanism of action was apparently mediated via activation of protein kinase C, as thimerosal potently stimulated binding of [3H]phorbol 12, 13-dibutyrate, and was without effect on store-operated calcium entry in cells treated with staurosporine or in cells with down-regulated protein kinase C. Thimerosal did not depolarize the membrane potential, as evaluated using patch-clamp in the whole-cell mode. In immunoprecipitates obtained with an antibody against plasma membrane Ca2+-ATPase, we observed several phosphorylated bands in cells stimulated with thimerosal. In conclusion, we have shown that thimerosal attenuates an increase in [Ca2+]i, probably by activating a plasma membrane Ca2+-ATPase.
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Affiliation(s)
- K Törnquist
- Department of Biology, Abo Akademi University, BioCity, Artillerigatan 6, 20520 Turku, Finland.
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18
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Gamberucci A, Fulceri R, Pralong W, Bánhegyi G, Marcolongo P, Watkins SL, Benedetti A. Caffeine releases a glucose-primed endoplasmic reticulum Ca2+ pool in the insulin secreting cell line INS-1. FEBS Lett 1999; 446:309-12. [PMID: 10100864 DOI: 10.1016/s0014-5793(99)00220-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Caffeine mobilized an intracellular Ca2+ pool in intact fura-2-loaded INS-1 cells in suspension exposed to high (16 mM) [glucose], while a minor effect was observed with low (2 mM) [glucose]. Cells were kept in a medium containing diaxozide or no Ca2+ to prevent the influx of extracellular Ca2+. The caffeine-sensitive intracellular Ca2+ pool was within the endoplasmic reticulum since it was depleted by the inhibitor of the reticular Ca2+ pumps thapsigargin and the InsP3-dependent agonist carbachol. No effect of caffeine was observed in the parent glucose-insensitive RINmF5 cells. In microsomes from INS-1 but not RINmF5 cells, the type 2 ryanodine receptor was present as revealed by Western blotting. It was concluded that the endoplasmic reticulum of INS-1 cells possesses caffeine-sensitive type 2 ryanodine receptors Ca2+ channels.
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Affiliation(s)
- A Gamberucci
- Istituto di Patologia Generale, Università di Siena, Italy
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19
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de Lamirande E, Gagnon C. Paradoxical effect of reagents for sulfhydryl and disulfide groups on human sperm capacitation and superoxide production. Free Radic Biol Med 1998; 25:803-17. [PMID: 9823546 DOI: 10.1016/s0891-5849(98)00156-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Spermatozoa must undergo capacitation prior to fertilization. In humans, this process appears regulated by oxidoreduction reactions. We investigated the possibility that these reactions involved the sulfhydryl-disulfide pair, which offers a reversible regulation of cellular processes. The effects of reagents targeted for sulfhydryl and disulfide groups on human sperm capacitation, superoxide (O2-.) generation and protein tyrosine phosphorylation were evaluated. The sulfhydryl targeted agents, phenylarsine oxide (PAO), diamide, dithiopyridine (DTP), N-ethylmaleimide (NEM), maleimidylpropionyl biocytin (MPB), p-chloromercuribenzoic acid (PCMB), and bromobimane analogs (mBBr and qBBr) triggered sperm capacitation to levels comparable to those observed with a biological inducer, fetal cord serum ultrafiltrate (FCSu). Capacitation induced by NEM, MPB, PCMB, and PAO was prevented by superoxide dismutase (SOD) and associated with an increased sperm production of O2-.. However, SOD did not affect the increase in protein tyrosine phosphorylation of spermatozoa treated with NEM, PAO, or MPB. Disulfide reductants, dithiothreitol (DTT), thioredoxin (TRX), glutathione (GSH), tris-(2-carboxyethyl) phosphine (TCEP), and tris-(2-cyanoethyl) phosphine (TCP) partially to totally inhibited FCSu-induced sperm capacitation and O2-. production. TCEP, DTT, and TRX decreased the capacitation-associated tyrosine phosphorylation of sperm proteins. The strong time-dependent increase of sperm membrane sulfhydryl groups exposed to the extracellular space occurring during the first hour of capacitation could indicate an important rearrangement of sulfhydryl carrying proteins during the initiation of capacitation. Therefore, protein sulfhydryl-disulfide status may be important for the regulation of human sperm capacitation and the mechanisms involved may be complex and multifactorial.
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Affiliation(s)
- E de Lamirande
- Urology Research Laboratory, Royal Victoria Hospital, Montréal, Québec, Canada
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20
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Misra UK, Gawdi G, Lewis JG, Pizzo SV. Alterations in calcium metabolism in murine macrophages by the benzene metabolite 1,4-benzoquinone. Toxicol Appl Pharmacol 1998; 151:1-8. [PMID: 9705881 DOI: 10.1006/taap.1998.8415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exposure of murine peritoneal macrophages to very low concentrations of 1,4-benzoquinone (BQ) induced immediate increases in intracellular Ca2+ concentrations ([Ca2+]i). Increases in [Ca2+]i were induced by concentrations as low as 5 nM and the response was dose dependent and linear up to 1 microM. The sources of Ca2+ were from both internal inositol triphosphate (IP3)-sensitive and -insensitive sites and from the external medium. BQ did not induce IP3 formation and did not affect binding to its receptors. 1, 4-Hydroquinone had no effect on [Ca2+]i. Catechol did elicit some increases in [Ca2+]i, but did so only at much higher concentrations (5 microM). The action of BQ was almost identical to that of the established Ca2+-ATPase inhibitor thapsigargin except that there were some intracellular stores of Ca2+ released by thapsigargin that were not released by BQ. BQ also was mitogenic for macrophages in conjunction with phorbol myristate acetate. These data suggest that BQ raises [Ca2+]i by inhibition of Ca2+-ATPases, is a comitogen, and does so at concentrations that could be achieved in vivo in the general urban population.
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MESH Headings
- Animals
- Benzoquinones/toxicity
- Calcium/metabolism
- Calcium Channels/drug effects
- Calcium Channels/metabolism
- Calcium-Transporting ATPases/antagonists & inhibitors
- Carcinogens/toxicity
- Catechols/toxicity
- Cells, Cultured
- Dithiothreitol/pharmacology
- Dose-Response Relationship, Drug
- Enzyme Inhibitors/toxicity
- Glutathione/pharmacology
- Hydroquinones/toxicity
- Inositol 1,4,5-Trisphosphate/analysis
- Inositol 1,4,5-Trisphosphate/biosynthesis
- Inositol 1,4,5-Trisphosphate Receptors
- Macrophages, Peritoneal/drug effects
- Macrophages, Peritoneal/metabolism
- Mice
- Mice, Inbred C57BL
- Mutagens/toxicity
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/metabolism
- Sulfhydryl Reagents/pharmacology
- Tetradecanoylphorbol Acetate/toxicity
- Thapsigargin/toxicity
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Affiliation(s)
- U K Misra
- Department of Pathology, Duke University Medical Center, Durham, North Carolina, 27710, USA
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Islam MS, Leibiger I, Leibiger B, Rossi D, Sorrentino V, Ekström TJ, Westerblad H, Andrade FH, Berggren PO. In situ activation of the type 2 ryanodine receptor in pancreatic beta cells requires cAMP-dependent phosphorylation. Proc Natl Acad Sci U S A 1998; 95:6145-50. [PMID: 9600932 PMCID: PMC27605 DOI: 10.1073/pnas.95.11.6145] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Molecular mechanisms that regulate in situ activation of ryanodine receptors (RY) in different cells are poorly understood. Here we demonstrate that caffeine (10 mM) released Ca2+ from the endoplasmic reticulum (ER) in the form of small spikes in only 14% of cultured fura-2 loaded beta cells from ob/ob mice. Surprisingly, when forskolin, an activator of adenylyl cyclase was present, caffeine induced larger Ca2+ spikes in as many as 60% of the cells. Forskolin or the phosphodiesterase-resistant PKA activator Sp-cAMPS alone did not release Ca2+ from ER. 4-Chloro-3-ethylphenol (4-CEP), an agent that activates RYs in other cell systems, released Ca2+ from ER, giving rise to a slow and small increase in [Ca2+]i in beta cells. Prior exposure of cells to forskolin or caffeine (5 mM) qualitatively altered Ca2+ release by 4-CEP, giving rise to Ca2+ spikes. In glucose-stimulated beta cells forskolin induced Ca2+ spikes that were enhanced by 3,9-dimethylxanthine, an activator of RYs. Analysis of RNA from islets and insulin-secreting betaTC-3-cells by RNase protection assay, using type-specific RY probes, revealed low-level expression of mRNA for the type 2 isoform of the receptor (RY2). We conclude that in situ activation of RY2 in beta cells requires cAMP-dependent phosphorylation, a process that recruits the receptor in a functionally operative form.
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Affiliation(s)
- M S Islam
- The Rolf Luft Center for Diabetes Research, Department of Molecular Medicine, Karolinska Institute, S-171 76 Stockholm, Sweden
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