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Rönkkö J, Rodriguez Y, Rasila T, Torregrosa-Muñumer R, Pennonen J, Kvist J, Kuuluvainen E, Bosch LVD, Hietakangas V, Bultynck G, Tyynismaa H, Ylikallio E. Human IP 3 receptor triple knockout stem cells remain pluripotent despite altered mitochondrial metabolism. Cell Calcium 2023; 114:102782. [PMID: 37481871 DOI: 10.1016/j.ceca.2023.102782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/14/2023] [Accepted: 07/13/2023] [Indexed: 07/25/2023]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP3Rs) are ER Ca2+-release channels that control a broad set of cellular processes. Animal models lacking IP3Rs in different combinations display severe developmental phenotypes. Given the importance of IP3Rs in human diseases, we investigated their role in human induced pluripotent stem cells (hiPSC) by developing single IP3R and triple IP3R knockouts (TKO). Genome edited TKO-hiPSC lacking all three IP3R isoforms, IP3R1, IP3R2, IP3R3, failed to generate Ca2+ signals in response to agonists activating GPCRs, but retained stemness and pluripotency. Steady state metabolite profiling and flux analysis of TKO-hiPSC indicated distinct alterations in tricarboxylic acid cycle metabolites consistent with a deficiency in their pyruvate utilization via pyruvate dehydrogenase, shifting towards pyruvate carboxylase pathway. These results demonstrate that IP3Rs are not essential for hiPSC identity and pluripotency but regulate mitochondrial metabolism. This set of knockout hiPSC is a valuable resource for investigating IP3Rs in human cell types of interest.
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Affiliation(s)
- Julius Rönkkö
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Yago Rodriguez
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Tiina Rasila
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Rubén Torregrosa-Muñumer
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Jana Pennonen
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Jouni Kvist
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Emilia Kuuluvainen
- Molecular and Integrative Bioscience Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland; Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, 00790, Finland
| | - Ludo Van Den Bosch
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute, KU Leuven - University of Leuven, 3000, Leuven, Belgium; VIB Center for Brain & Disease Research, Laboratory of Neurobiology, 3000, Leuven, Belgium
| | - Ville Hietakangas
- Molecular and Integrative Bioscience Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland; Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, 00790, Finland
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Leuven, 3000, Belgium
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland
| | - Emil Ylikallio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland; Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, 00290, Finland.
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NavaneethaKrishnan S, Law V, Lee J, Rosales JL, Lee KY. Cdk5 regulates IP3R1-mediated Ca 2+ dynamics and Ca 2+-mediated cell proliferation. Cell Mol Life Sci 2022; 79:495. [PMID: 36001172 PMCID: PMC9402492 DOI: 10.1007/s00018-022-04515-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 07/19/2022] [Accepted: 08/04/2022] [Indexed: 12/02/2022]
Abstract
Loss of cyclin-dependent kinase 5 (Cdk5) in the mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) increases ER–mitochondria tethering and ER Ca2+ transfer to the mitochondria, subsequently increasing mitochondrial Ca2+ concentration ([Ca2+]mt). This suggests a role for Cdk5 in regulating intracellular Ca2+ dynamics, but how Cdk5 is involved in this process remains to be explored. Using ex vivo primary mouse embryonic fibroblasts (MEFs) isolated from Cdk5−/− mouse embryos, we show here that loss of Cdk5 causes an increase in cytosolic Ca2+concentration ([Ca2+]cyt), which is not due to reduced internal Ca2+ store capacity or increased Ca2+ influx from the extracellular milieu. Instead, by stimulation with ATP that mediates release of Ca2+ from internal stores, we determined that the rise in [Ca2+]cyt in Cdk5−/− MEFs is due to increased inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ release from internal stores. Cdk5 interacts with the IP3R1 Ca2+ channel and phosphorylates it at Ser421. Such phosphorylation controls IP3R1-mediated Ca2+ release as loss of Cdk5, and thus, loss of IP3R1 Ser421 phosphorylation triggers an increase in IP3R1-mediated Ca2+ release in Cdk5−/− MEFs, resulting in elevated [Ca2+]cyt. Elevated [Ca2+]cyt in these cells further induces the production of reactive oxygen species (ROS), which upregulates the levels of Nrf2 and its targets, Prx1 and Prx2. Cdk5−/− MEFs, which have elevated [Ca2+]cyt, proliferate at a faster rate compared to wt, and Cdk5−/− embryos have increased body weight and size compared to their wt littermates. Taken together, we show that altered IP3R1-mediated Ca2+ dynamics due to Cdk5 loss correspond to accelerated cell proliferation that correlates with increased body weight and size in Cdk5−/− embryos.
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Affiliation(s)
- Saranya NavaneethaKrishnan
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Vincent Law
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Jungkwon Lee
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Jesusa L Rosales
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Ki-Young Lee
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer and Alberta Children's Hospital Research Institutes, Cumming School of Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
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NavaneethaKrishnan S, Rosales JL, Lee KY. mPTP opening caused by Cdk5 loss is due to increased mitochondrial Ca 2+ uptake. Oncogene 2020; 39:2797-2806. [PMID: 32024968 PMCID: PMC7098883 DOI: 10.1038/s41388-020-1188-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 01/02/2020] [Accepted: 01/23/2020] [Indexed: 11/09/2022]
Abstract
We previously demonstrated that loss of Cdk5 in breast cancer cells promotes ROS-mediated cell death by inducing mitochondrial permeability transition pore (mPTP) opening (Oncogene 37, 1788–1804). However, the molecular mechanism by which Cdk5 loss causes mPTP opening remains to be investigated. Using primary mouse embryonic fibroblasts (MEFs) isolated from Cdk5−/− mouse embryos, we show that absence of Cdk5 causes a significant increase in both mPTP opening and mitochondrial Ca2+ level. Analysis of subcellular fractions of MEFs demonstrates that Cdk5 localizes in the mitochondria-associated endoplasmic reticulum (ER) membrane (MAM) and Cdk5 loss in MAMs causes increased ER-mitochondria tethering, a process required for Ca2+ transfer from the ER to the mitochondria. Loss of Cdk5 also causes increased ATP-mediated mitochondrial Ca2+ uptake from the ER. Inhibition of ER Ca2+ release or mitochondrial Ca2+ uptake in Cdk5−/− MEFs prevents mPTP opening, indicating that mPTP opening in Cdk5−/− MEFs is due to increased Ca2+ transfer from the ER to the mitochondria. Altogether, our findings suggest that Cdk5 in MAMs regulates mitochondrial Ca2+ homeostasis that is disturbed upon Cdk5 loss, which leads to mPTP opening.
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Affiliation(s)
- Saranya NavaneethaKrishnan
- Departments of Cell Biology and Anatomy, Arnie Charbonneau Cancer Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Jesusa L Rosales
- Departments of Cell Biology and Anatomy, Arnie Charbonneau Cancer Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Ki-Young Lee
- Departments of Cell Biology and Anatomy, Arnie Charbonneau Cancer Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
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Zhang X, Lee MD, Wilson C, McCarron JG. Hydrogen peroxide depolarizes mitochondria and inhibits IP 3-evoked Ca 2+ release in the endothelium of intact arteries. Cell Calcium 2019; 84:102108. [PMID: 31715384 PMCID: PMC6891240 DOI: 10.1016/j.ceca.2019.102108] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/30/2019] [Accepted: 10/30/2019] [Indexed: 12/30/2022]
Abstract
H2O2 is produced by several cell processes including mitochondria and may act as an intracellular messenger and cell-cell signalling molecule. Spontaneous local Ca2+ signals and IP3-evoked Ca2+ increases were inhibited by H2O2. H2O2 suppression of IP3-evoked Ca2+ signalling may be mediated by mitochondria via a decrease in the mitochondrial membrane potential. H2O2-induced mitochondrial depolarization and inhibition of IP3-evoked Ca2+ release, may protect mitochondria from Ca2+ overload during IP3-linked Ca2+ signals.
Hydrogen peroxide (H2O2) is a mitochondrial-derived reactive oxygen species (ROS) that regulates vascular signalling transduction, vasocontraction and vasodilation. Although the physiological role of ROS in endothelial cells is acknowledged, the mechanisms underlying H2O2 regulation of signalling in native, fully-differentiated endothelial cells is unresolved. In the present study, the effects of H2O2 on Ca2+ signalling were investigated in the endothelium of intact rat mesenteric arteries. Spontaneous local Ca2+ signals and acetylcholine evoked Ca2+ increases were inhibited by H2O2. H2O2 inhibition of acetylcholine-evoked Ca2+ signals was reversed by catalase. H2O2 exerts its inhibition on the IP3 receptor as Ca2+ release evoked by photolysis of caged IP3 was supressed by H2O2. H2O2 suppression of IP3-evoked Ca2+ signalling may be mediated by mitochondria. H2O2 depolarized mitochondria membrane potential. Acetylcholine-evoked Ca2+ release was inhibited by depolarisation of the mitochondrial membrane potential by the uncoupler carbonyl cyanide 3-chlorophenylhydrazone (CCCP) or complex 1 inhibitor, rotenone. We propose that the suppression of IP3-evoked Ca2+ release by H2O2 arises from the decrease in mitochondrial membrane potential. These results suggest that mitochondria may protect themselves against Ca2+ overload during IP3-linked Ca2+ signals by a H2O2 mediated negative feedback depolarization of the organelle and inhibition of IP3-evoked Ca2+ release.
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Affiliation(s)
- Xun Zhang
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, UK
| | - Matthew D Lee
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, UK
| | - Calum Wilson
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, UK
| | - John G McCarron
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, UK.
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Wilson C, Lee MD, Heathcote HR, Zhang X, Buckley C, Girkin JM, Saunter CD, McCarron JG. Mitochondrial ATP production provides long-range control of endothelial inositol trisphosphate-evoked calcium signaling. J Biol Chem 2019; 294:737-758. [PMID: 30498088 PMCID: PMC6341391 DOI: 10.1074/jbc.ra118.005913] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 11/27/2018] [Indexed: 01/09/2023] Open
Abstract
Endothelial cells are reported to be glycolytic and to minimally rely on mitochondria for ATP generation. Rather than providing energy, mitochondria in endothelial cells may act as signaling organelles that control cytosolic Ca2+ signaling or modify reactive oxygen species (ROS). To control Ca2+ signaling, these organelles are often observed close to influx and release sites and may be tethered near Ca2+ transporters. In this study, we used high-resolution, wide-field fluorescence imaging to investigate the regulation of Ca2+ signaling by mitochondria in large numbers of endothelial cells (∼50 per field) in intact arteries from rats. We observed that mitochondria were mostly spherical or short-rod structures and were distributed widely throughout the cytoplasm. The density of these organelles did not increase near contact sites with smooth muscle cells. However, local inositol trisphosphate (IP3)-mediated Ca2+ signaling predominated near these contact sites and required polarized mitochondria. Of note, mitochondrial control of Ca2+ signals occurred even when mitochondria were far from Ca2+ release sites. Indeed, the endothelial mitochondria were mobile and moved throughout the cytoplasm. Mitochondrial control of Ca2+ signaling was mediated by ATP production, which, when reduced by mitochondrial depolarization or ATP synthase inhibition, eliminated local IP3-mediated Ca2+ release events. ROS buffering did not significantly alter local Ca2+ release events. These results highlight the importance of mitochondrial ATP production in providing long-range control of endothelial signaling via IP3-evoked local Ca2+ release in intact endothelium.
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Affiliation(s)
- Calum Wilson
- From the Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow G4 0RE, Scotland, United Kingdom and
| | - Matthew D Lee
- From the Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow G4 0RE, Scotland, United Kingdom and
| | - Helen R Heathcote
- From the Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow G4 0RE, Scotland, United Kingdom and
| | - Xun Zhang
- From the Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow G4 0RE, Scotland, United Kingdom and
| | - Charlotte Buckley
- From the Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow G4 0RE, Scotland, United Kingdom and
| | - John M Girkin
- the Centre for Advanced Instrumentation, Biophysical Sciences Institute, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Christopher D Saunter
- the Centre for Advanced Instrumentation, Biophysical Sciences Institute, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - John G McCarron
- From the Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow G4 0RE, Scotland, United Kingdom and
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Vervloessem T, Yule DI, Bultynck G, Parys JB. The type 2 inositol 1,4,5-trisphosphate receptor, emerging functions for an intriguing Ca²⁺-release channel. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1992-2005. [PMID: 25499268 DOI: 10.1016/j.bbamcr.2014.12.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/19/2022]
Abstract
The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) type 2 (IP3R2) is an intracellular Ca²⁺-release channel located on the endoplasmic reticulum (ER). IP3R2 is characterized by a high sensitivity to both IP3 and ATP and is biphasically regulated by Ca²⁺. Furthermore, IP3R2 is modulated by various protein kinases. In addition to its regulation by protein kinase A, IP3R2 forms a complex with adenylate cyclase 6 and is directly regulated by cAMP. Finally, in the ER, IP3R2 is less mobile than the other IP3R isoforms, while its functional properties appear dominant in heterotetramers. These properties make the IP3R2 a Ca²⁺ channel with exquisite properties for setting up intracellular Ca²⁺ signals with unique characteristics. IP3R2 plays a crucial role in the function of secretory cell types (e.g. pancreatic acinar cells, hepatocytes, salivary gland, eccrine sweat gland). In cardiac myocytes, the role of IP3R2 appears more complex, because, together with IP3R1, it is needed for normal cardiogenesis, while its aberrant activity is implicated in cardiac hypertrophy and arrhythmias. Most importantly, its high sensitivity to IP3 makes IP3R2 a target for anti-apoptotic proteins (e.g. Bcl-2) in B-cell cancers. Disrupting IP3R/Bcl-2 interaction therefore leads in those cells to increased Ca²⁺ release and apoptosis. Intriguingly, IP3R2 is not only implicated in apoptosis but also in the induction of senescence, another tumour-suppressive mechanism. These results were the first to unravel the physiological and pathophysiological role of IP3R2 and we anticipate that further progress will soon be made in understanding the function of IP3R2 in various tissues and organs.
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Affiliation(s)
- Tamara Vervloessem
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - David I Yule
- University of Rochester, Department of Pharmacology and Physiology, Rochester, NY, USA
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - Jan B Parys
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium.
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Saleem H, Tovey SC, Molinski TF, Taylor CW. Interactions of antagonists with subtypes of inositol 1,4,5-trisphosphate (IP3) receptor. Br J Pharmacol 2014; 171:3298-312. [PMID: 24628114 PMCID: PMC4080982 DOI: 10.1111/bph.12685] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/26/2014] [Accepted: 03/05/2014] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND AND PURPOSE Inositol 1,4,5-trisphosphate receptors (IP3 Rs) are intracellular Ca(2+) channels. Interactions of the commonly used antagonists of IP3Rs with IP3R subtypes are poorly understood. EXPERIMENTAL APPROACH IP3-evoked Ca(2+) release from permeabilized DT40 cells stably expressing single subtypes of mammalian IP3R was measured using a luminal Ca(2+) indicator. The effects of commonly used antagonists on IP3-evoked Ca(2+) release and (3) H-IP3 binding were characterized. KEY RESULTS Functional analyses showed that heparin was a competitive antagonist of all IP3R subtypes with different affinities for each (IP3R3 > IP3R1 ≥ IP3R2). This sequence did not match the affinities for heparin binding to the isolated N-terminal from each IP3R subtype. 2-aminoethoxydiphenyl borate (2-APB) and high concentrations of caffeine selectively inhibited IP3R1 without affecting IP3 binding. Neither Xestospongin C nor Xestospongin D effectively inhibited IP3-evoked Ca(2+) release via any IP3R subtype. CONCLUSIONS AND IMPLICATIONS Heparin competes with IP3, but its access to the IP3-binding core is substantially hindered by additional IP3R residues. These interactions may contribute to its modest selectivity for IP3R3. Practicable concentrations of caffeine and 2-APB inhibit only IP3R1. Xestospongins do not appear to be effective antagonists of IP3Rs.
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Affiliation(s)
- Huma Saleem
- Department of Pharmacology, University of CambridgeCambridge, UK
| | - Stephen C Tovey
- Department of Pharmacology, University of CambridgeCambridge, UK
| | | | - Colin W Taylor
- Department of Pharmacology, University of CambridgeCambridge, UK
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Bosche B, Schäfer M, Graf R, Härtel FV, Schäfer U, Noll T. Lithium prevents early cytosolic calcium increase and secondary injurious calcium overload in glycolytically inhibited endothelial cells. Biochem Biophys Res Commun 2013; 434:268-72. [PMID: 23541580 DOI: 10.1016/j.bbrc.2013.03.047] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 03/18/2013] [Indexed: 11/26/2022]
Abstract
Cytosolic free calcium concentration ([Ca(2+)]i) is a central signalling element for the maintenance of endothelial barrier function. Under physiological conditions, it is controlled within narrow limits. Metabolic inhibition during ischemia/reperfusion, however, induces [Ca(2+)]i overload, which results in barrier failure. In a model of cultured porcine aortic endothelial monolayers (EC), we addressed the question of whether [Ca(2+)]i overload can be prevented by lithium treatment. [Ca(2+)]i and ATP were analysed using Fura-2 and HPLC, respectively. The combined inhibition of glycolytic and mitochondrial ATP synthesis by 2-desoxy-d-glucose (5mM; 2-DG) plus sodium cyanide (5mM; NaCN) caused a significant decrease in cellular ATP content (14±1 nmol/mg protein vs. 18±1 nmol/mg protein in the control, n=6 culture dishes, P<0.05), an increase in [Ca(2+)]i (278±24 nM vs. 71±2 nM in the control, n=60 cells, P<0.05), and the formation of gaps between adjacent EC. These observations indicate that there is impaired barrier function at an early state of metabolic inhibition. Glycolytic inhibition alone by 10mM 2-DG led to a similar decrease in ATP content (14±2 nmol/mg vs. 18±1 nmol/mg in the control, P<0.05) with a delay of 5 min. The [Ca(2+)]i response of EC was biphasic with a peak after 1 min (183±6 nM vs. 71±1 nM, n=60 cells, P<0.05) followed by a sustained increase in [Ca(2+)]i. A 24-h pre-treatment with 10mM of lithium chloride before the inhibition of ATP synthesis abolished both phases of the 2-DG-induced [Ca(2+)]i increase. This effect was not observed when lithium chloride was added simultaneously with 2-DG. We conclude that lithium chloride abolishes the injurious [Ca(2+)]i overload in EC and that this most likely occurs by preventing inositol 3-phosphate-sensitive Ca(2+)-release from the endoplasmic reticulum. Though further research is needed, these findings provide a novel option for therapeutic strategies to protect the endothelium against imminent barrier failure.
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Affiliation(s)
- Bert Bosche
- Department of Neurology, University of Duisburg-Essen, Germany.
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Bononi A, Missiroli S, Poletti F, Suski JM, Agnoletto C, Bonora M, De Marchi E, Giorgi C, Marchi S, Patergnani S, Rimessi A, Wieckowski MR, Pinton P. Mitochondria-Associated Membranes (MAMs) as Hotspot Ca2+ Signaling Units. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:411-37. [DOI: 10.1007/978-94-007-2888-2_17] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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10
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Betzenhauser MJ, Yule DI. Regulation of inositol 1,4,5-trisphosphate receptors by phosphorylation and adenine nucleotides. CURRENT TOPICS IN MEMBRANES 2010; 66:273-98. [PMID: 22353484 DOI: 10.1016/s1063-5823(10)66012-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
- Matthew J Betzenhauser
- Department of Physiology and Cellular Biophysics, Columbia University Medical School, New York City, New York, USA
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11
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Yule DI, Betzenhauser MJ, Joseph SK. Linking structure to function: Recent lessons from inositol 1,4,5-trisphosphate receptor mutagenesis. Cell Calcium 2010; 47:469-79. [PMID: 20510450 DOI: 10.1016/j.ceca.2010.04.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 04/21/2010] [Accepted: 04/22/2010] [Indexed: 12/12/2022]
Abstract
Great insight has been gained into the structure and function of the inositol 1,4,5 trisphosphate receptor (InsP(3)R) by studies employing mutagenesis of the cDNA encoding the receptor. Notably, early studies using this approach defined the key constituents required for InsP(3) binding in the N-terminus and the membrane spanning regions in the C-terminal domain responsible for channel formation, targeting and function. In this article we evaluate recent studies which have used a similar approach to investigate key residues underlying the in vivo modulation by select regulatory factors. In addition, we review studies defining the structural requirements in the channel domain which comprise the conduction pathway and are suggested to be involved in the gating of the channel.
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Affiliation(s)
- David I Yule
- Department of Pharmacology and Physiology, University of Rochester, NY, United States.
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12
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Rizzuto R, Marchi S, Bonora M, Aguiari P, Bononi A, De Stefani D, Giorgi C, Leo S, Rimessi A, Siviero R, Zecchini E, Pinton P. Ca(2+) transfer from the ER to mitochondria: when, how and why. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1787:1342-51. [PMID: 19341702 PMCID: PMC2730423 DOI: 10.1016/j.bbabio.2009.03.015] [Citation(s) in RCA: 342] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 03/21/2009] [Accepted: 03/24/2009] [Indexed: 10/25/2022]
Abstract
The heterogenous subcellular distribution of a wide array of channels, pumps and exchangers allows extracellular stimuli to induce increases in cytoplasmic Ca(2+) concentration ([Ca(2+)]c) with highly defined spatial and temporal patterns, that in turn induce specific cellular responses (e.g. contraction, secretion, proliferation or cell death). In this extreme complexity, the role of mitochondria was considered marginal, till the direct measurement with targeted indicators allowed to appreciate that rapid and large increases of the [Ca(2+)] in the mitochondrial matrix ([Ca(2+)]m) invariably follow the cytosolic rises. Given the low affinity of the mitochondrial Ca(2+) transporters, the close proximity to the endoplasmic reticulum (ER) Ca(2+)-releasing channels was shown to be responsible for the prompt responsiveness of mitochondria. In this review, we will summarize the current knowledge of: i) the mitochondrial and ER Ca(2+) channels mediating the ion transfer, ii) the structural and molecular foundations of the signaling contacts between the two organelles, iii) the functional consequences of the [Ca(2+)]m increases, and iv) the effects of oncogene-mediated signals on mitochondrial Ca(2+) homeostasis. Despite the rapid progress carried out in the latest years, a deeper molecular understanding is still needed to unlock the secrets of Ca(2+) signaling machinery.
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Affiliation(s)
- Rosario Rizzuto
- Dept. Biomedical Sciences, University of Padua, Via Colombo 3, Padua 35121, Italy.
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Mikoshiba K, Furuichi T, Miyawaki A, Yoshikawa S, Maeda N, Niinobe M, Nakade S, Nakagawa T, Okano H, Aruga J. The inositol 1,4,5-trisphosphate receptor. CIBA FOUNDATION SYMPOSIUM 2007; 164:17-29; discussion 29-35. [PMID: 1327678 DOI: 10.1002/9780470514207.ch3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Inositol 1,4,5-trisphosphate (InsP3) is a second messenger that releases Ca2+ from its intracellular stores. The InsP3 receptor has been purified and its cDNA has been cloned. We have found that the InsP3 receptor is identical to P400 protein, first identified as a protein enriched in cerebellar Purkinje cells. We have generated an L-fibroblast cell transfectant that produces cDNA-derived InsP3 receptors. The protein displays high affinity and specificity for InsP3. InsP3 induces greater Ca2+ release from membrane vesicles from transfected cells than from those from control L-fibroblasts. After incorporation of the purified InsP3 receptor into lipid bilayers InsP3-induced Ca2+ currents were demonstrated. These results suggest that the InsP3 receptor is involved in physiological Ca2+ release. Immunogold labelling using monoclonal antibodies against the receptor showed that it is highly concentrated on the smooth-surfaced endoplasmic reticulum and slightly on the outer nuclear membrane and rough endoplasmic reticulum; no labelling of Golgi apparatus, mitochondria and plasmalemma was seen. Cross-linking experiments showed that the receptor forms a homotetramer. The approximately 650 N-terminal amino acids are highly conserved between mouse and Drosophila, and this region contains the critical sequences for InsP3 binding. We have investigated the heterogeneity of the InsP3 receptor using the polymerase chain reaction and have found novel subtypes of the mouse InsP3 receptor that are expressed in a tissue-specific and developmentally specific manner.
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Affiliation(s)
- K Mikoshiba
- Institute for Protein Research, Osaka University, Japan
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14
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Exton JH. The roles of calcium and phosphoinositides in the mechanisms of alpha 1-adrenergic and other agonists. Rev Physiol Biochem Pharmacol 2005; 111:117-224. [PMID: 2906170 DOI: 10.1007/bfb0033873] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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15
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Schäfer M, Bahde D, Bosche B, Ladilov Y, Schäfer C, Piper HM, Noll T. Modulation of early [Ca2+]i rise in metabolically inhibited endothelial cells by xestospongin C. Am J Physiol Heart Circ Physiol 2001; 280:H1002-10. [PMID: 11179041 DOI: 10.1152/ajpheart.2001.280.3.h1002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
When energy metabolism is disrupted, endothelial cells lose Ca(2+) from endoplasmic reticulum (ER) and the cytosolic Ca(2+) concentration ([Ca(2+)](i)) increases. The importance of glycolytic energy production and the mechanism of Ca(2+) loss from the ER were analyzed. Endothelial cells from porcine aorta in culture and in situ were used as models. 2-Deoxy-D-glucose (2-DG, 10 mM), an inhibitor of glycolysis, caused an increase in [Ca(2+)](i) (measured with fura 2) within 1 min when total cellular ATP contents were not yet affected. Stimulation of oxidative energy production with pyruvate (5 mM) did not attenuate this 2-DG-induced rise of [Ca(2+)](i), while this maneuver preserved cellular ATP contents. The inhibitor of ER-Ca(2+)-ATPase, thapsigargin (10 nM), augmented the 2-DG-induced rise of [Ca(2+)](i). Xestospongin C (3 microM), an inhibitor of D-myo-inositol 3-phosphate [Ins(3)P]-sensitive ER-Ca(2+) release, abolished the rise. The results demonstrate that the ER of endothelial cells is very sensitive to glycolytic metabolic inhibition. When this occurs, the ER Ca(2+) store is discharged by opening of the Ins(3)P-sensitive release channel. Xestospongin C can effectively suppress the early [Ca(2+)](i) rise in metabolically inhibited endothelial cells.
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Affiliation(s)
- M Schäfer
- Physiologisches Institut, Justus-Liebig-Universität, D-35392 Giessen, Germany.
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16
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Abstract
Many hormones and neurotransmitters raise intracellular calcium (Ca(2+)) by generating InsP(3) and activating the inositol 1,4, 5-trisphosphate receptor (InsP(3)R). Multiple isoforms with distinct InsP(3) binding properties () have been identified (). The type III InsP(3)R lacks Ca(2+)-dependent inhibition, a property that makes it ideal for signal initiation (). Regulation of the type III InsP(3)R by InsP(3) and ATP was explored in detail using planar lipid bilayers. In comparison to the type I InsP(3)R, the type III InsP(3)R required a higher concentration of InsP(3) to reach maximal channel activity (EC(50) of 3.2 microM versus 0.5 microM for the types III and I InsP(3)R, respectively). However, the type III InsP(3)R did reach a 2.5-fold higher level of activity. Although activation by InsP(3) was isoform-specific, regulation by ATP was similar for both isoforms. In the presence of 2 microM InsP(3), low ATP concentrations (<6 mM) increased the open probability and mean open time. High ATP concentrations (>6 mM) decreased channel activity. These results illustrate the complex nature of type III InsP(3)R regulation. Enhanced channel activity in the presence of high InsP(3) may be important during periods of prolonged stimulation, whereas allosteric modulation by ATP may help to modulate intracellular Ca(2+) signaling.
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MESH Headings
- Adenosine Triphosphate/metabolism
- Adenosine Triphosphate/pharmacology
- Allosteric Regulation/drug effects
- Animals
- Binding, Competitive/drug effects
- Calcium Channels/drug effects
- Calcium Channels/metabolism
- Dose-Response Relationship, Drug
- Endoplasmic Reticulum/drug effects
- Endoplasmic Reticulum/metabolism
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate/pharmacology
- Inositol 1,4,5-Trisphosphate Receptors
- Insulinoma/metabolism
- Insulinoma/pathology
- Microsomes/drug effects
- Microsomes/metabolism
- Protein Isoforms/drug effects
- Protein Isoforms/metabolism
- Rats
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/metabolism
- Substrate Specificity
- Tumor Cells, Cultured
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Affiliation(s)
- R E Hagar
- Department of Physiology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
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17
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Zimmermann B. Control of InsP3-induced Ca2+ oscillations in permeabilized blowfly salivary gland cells: contribution of mitochondria. J Physiol 2000; 525 Pt 3:707-19. [PMID: 10856123 PMCID: PMC2269978 DOI: 10.1111/j.1469-7793.2000.t01-1-00707.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Many agonists linked to the generation of inositol 1,4, 5-trisphosphate (InsP3) and release of Ca2+ from intracellular stores induce repetitive transients in cytosolic Ca2+ whose frequency increases over a certain range of agonist concentrations. In order to investigate the mechanisms underlying this frequency modulation, the fluorescent Ca2+ sensor mag-fura-2 was loaded into intracellular calcium stores and used to monitor InsP3-induced dynamics of the intraluminal calcium concentration ([Ca2+]L) in secretory cells of permeabilized blowfly Calliphora vicina salivary glands. In this preparation, increasing concentrations of InsP3 induced graded decreases in [Ca2+]L that were often superimposed with repetitive [Ca2+]L transients produced by sequential Ca2+ release and re-uptake. These [Ca2+]L oscillations developed at frequencies of 3-11 min-1 unrelated to the concentration of InsP3 present. In contrast, incremental concentrations of InsP3 applied in the presence of the oxidizable mitochondrial substrates citrate, succinate, or pyruvate-malate induced repetitive [Ca2+]L transients whose frequency increased with the concentration of InsP3. This InsP3 concentration-dependent modulation of oscillation frequency was abolished after dissipating the mitochondrial membrane potential (Delta psi m) by combined treatment with carbonyl cyanide p-trifluoromethoxyphenyl hydrazone + oligomycin or after application of Ruthenium Red, an inhibitor of mitochondrial Ca2+ uptake. Taken together, the data indicate that energized mitochondria exert negative control over the frequency of InsP3-induced Ca2+ oscillations. It is concluded that mitochondria play a crucial role in determining the duration of the interspike period and, therefore, for the encoding of amplitude-modulated, InsP3-liberating stimuli into the frequency of cytosolic Ca2+ oscillations.
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Affiliation(s)
- B Zimmermann
- Institut für Zoophysiologie und Zellbiologie, Universität Potsdam, D-14471 Potsdam,
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18
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Somlyo AP, Wu X, Walker LA, Somlyo AV. Pharmacomechanical coupling: the role of calcium, G-proteins, kinases and phosphatases. Rev Physiol Biochem Pharmacol 1999; 134:201-34. [PMID: 10087910 DOI: 10.1007/3-540-64753-8_5] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The concept of pharmacomechanical coupling, introduced 30 years ago to account for physiological mechanisms that can regulate contraction of smooth muscle independently of the membrane potential, has since been transformed from a definition into what we now recognize as a complex of well-defined, molecular mechanisms. The release of Ca2+ from the SR by a chemical messenger, InsP3, is well known to be initiated not by depolarization, but by agonist-receptor interaction. Furthermore, this G-protein-coupled phosphatidylinositol cascade, one of many processes covered by the umbrella of pharmacomechanical coupling, is part of complex and general signal transduction mechanisms also operating in many non-muscle cells of diverse organisms. It is also clear that, although the major contractile regulatory mechanism of smooth muscle, phosphorylation/dephosphorylation of MLC20, is [Ca2+]-dependent, the activity of both the kinase and the phosphatase can also be modulated independently of [Ca2+]i. Sensitization to Ca2+ is attributed to inhibition of SMPP-1M, a process most likely dominated by activation of the monomeric GTP-binding protein RhoA that, in turn, activates Rho-kinase that phosphorylates the regulatory subunit of SMPP-1M and inhibits its myosin phosphatase activity. It is likely that the tonic phase of contraction activated by a variety of excitatory agonists is, at least in part, mediated by this Ca(2+)-sensitizing mechanism. Desensitization to Ca2+ can occur either through inhibitory phosphorylation of MLCK by other kinases or autophosphorylation and by activation of SMPP-1M by cyclic nucleotide-activated kinases, probably involving phosphorylation of a phosphatase activator. Based on our current understanding of the complexity of the many cross-talking signal transduction mechanisms that operate in cells, it is likely that, in the future, our current concepts will be refined, additional mechanisms of pharmacomechanical coupling will be recognized, and those contributing to the pathologenesis diseases, such as hypertension and asthma, will be identified.
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Affiliation(s)
- A P Somlyo
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville 22906-0011, USA
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19
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Landolfi B, Curci S, Debellis L, Pozzan T, Hofer AM. Ca2+ homeostasis in the agonist-sensitive internal store: functional interactions between mitochondria and the ER measured In situ in intact cells. J Cell Biol 1998; 142:1235-43. [PMID: 9732284 PMCID: PMC2149340 DOI: 10.1083/jcb.142.5.1235] [Citation(s) in RCA: 152] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Mitochondria have a well-established capacity to detect cytoplasmic Ca2+ signals resulting from the discharge of ER Ca2+ stores. Conversely, both the buffering of released Ca2+ and ATP production by mitochondria are predicted to influence ER Ca2+ handling, but this complex exchange has been difficult to assess in situ using conventional measurement techniques. Here we have examined this interaction in single intact BHK-21 cells by monitoring intraluminal ER [Ca2+] directly using trapped fluorescent low-affinity Ca2+ indicators. Treatment with mitochondrial inhibitors (FCCP, antimycin A, oligomycin, and rotenone) dramatically prolonged the refilling of stores after release with bradykinin. This effect was largely due to inhibition of Ca2+ entry pathways at the plasma membrane, but a significant component appears to arise from reduction of SERCA-mediated Ca2+ uptake, possibly as a consequence of ATP depletions in a localized subcellular domain. The rate of bradykinin-induced Ca2+ release was reduced to 51% of control by FCCP. This effect was largely overcome by loading cells with BAPTA-AM, highlighting the importance of mitochondrial Ca2+ buffering in shaping the release kinetics. However, mitochondria-specific ATP production was also a significant determinant of the release dynamic. Our data emphasize the localized nature of the interaction between these organelles, and show that competent mitochondria are essential for generating explosive Ca2+ signals.
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Affiliation(s)
- B Landolfi
- Istituto di Fisiologia Generale, Università degli Studi di Bari, Via Amendola 165/A, I-70126 Bari, Italy
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20
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Zhang L. Adaptation of pharmacomechanical coupling of vascular smooth muscle to chronic hypoxia. Comp Biochem Physiol A Mol Integr Physiol 1998; 119:661-7. [PMID: 9683404 DOI: 10.1016/s1095-6433(98)01002-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Hypoxia is one of the most common stresses that affect an organism's homeostasis. Although much is known of the mechanisms of the cellular and biochemical responses to acute hypoxia, relatively little is known of the mechanisms of the responses to prolonged or chronic hypoxia. Chronic hypoxia suppresses vascular smooth muscle contractility in many vascular beds. While the endothelium is likely to play a role, part of the mechanisms underlying chronic hypoxic-induced changes in vascular responses resides in the changes in receptor-mediated excitation-contraction coupling and/or signal transduction in the vascular smooth muscle. Recent studies have demonstrated that chronic hypoxia attenuates both receptor-second messenger and second messenger-contraction coupling efficiencies in the vascular smooth muscle. This suppression of pharmacomechanical coupling is likely to represent one of the adaptive mechanisms of vascular smooth muscle and to play an important role in an adjustment of vascular tone and blood flow under the stress of moderate chronic hypoxia.
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Affiliation(s)
- L Zhang
- Department of Pharmacology, Loma Linda University School of Medicine, California 92350, USA.
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21
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Oriji GK, Keiser HR. Protein kinase C mediates angiotensin II-induced contractions and the release of endothelin and prostacyclin in rat aortic rings. Prostaglandins Leukot Essent Fatty Acids 1997; 57:135-41. [PMID: 9250696 DOI: 10.1016/s0952-3278(97)90003-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Angiotensin II (Ang II) stimulation of vascular smooth muscle results in a myriad of intracellular signals that interact to produce the final physiologic response of the cell. We used rat aortic rings to investigate the role of protein kinase C (PKC) in Ang II-induced contractions and in the concomitant release of endothelin (ET) and prostacyclin (PGI2). Ang II (10(-9) M) produced a rapid contraction which was sustained for 10 min. When aortic rings were pretreated with graded concentrations of each of the four different inhibitors of PKC, that is, (i) 1-(5-isoquinolinesulfonylmethyl) piperazine (H7); (ii) 1-(5-isoquinolinesulfonyl) piperazine(CL); (iii) staurosporine; or (iv) calphostin C, inhibition of Ang II-induced contractions began at 10(-9) M, and was nearly complete at 10(-6) M. Ang II-induced contractions were associated with a 10-fold increase in the release of both ET and PGI2. Pretreatment with 10(-6) M of any one of the same four PKC inhibitors blocked Ang II-induced release of both ET and PGI2. Pretreatment with a blocker of the endothelin-A receptor, BQ123 (10(-6) M), inhibited, by approximately 50%, Ang II-induced contractions, and the release of both ET and PGI2. In aortic rings denuded of endothelium, Ang II-induced contractions, and the release of both ET and PGI2 were significantly reduced, compared to intact rings. We conclude that PKC mediates Ang II-induced contractions in rat aortic rings and that the secondary release of both ET and PGI2 during Ang II-induced contractions is mediated, at least in part, by PKC. In addition, approximately half of Ang II-induced contractile force and of PGI2 release is dependent upon the ET released from endothelial cells.
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Affiliation(s)
- G K Oriji
- Hypertension-Endocrine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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22
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23
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Paltauf-Doburzynska J, Graier WF. Temperature dependence of agonist-stimulated Ca2+ signaling in cultured endothelial cells. Cell Calcium 1997; 21:43-51. [PMID: 9056076 DOI: 10.1016/s0143-4160(97)90095-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In cultured endothelial cells, the temperature dependence of bradykinin-initiated Ca2+ signaling was studied using Fura-2 technique. Initially, the temperature dependence of the dissociation constant of Fura-2 for Ca2+ was investigated. Temperature-initiated changes in the apparent dissociation constant (K'D) using the ratio (F340/F380) were due to a hypsochromic shift in excitation wavelengths and changes in the effective dissociation constant of Fura-2 for Ca2+ (K"D). Equations were provided to correct the dissociation constant for Fura-2, either for using the common ratio (F340/F380) or the shift corrected ratio (F340-delta lambda/F380-delta lambda). In a simple experimental protocol, the temperature dependence of the transient increase in free intracellular Ca2+ to bradykinin (i.e. Ca2+ release, sequestration and extrusion) and Ca2+/Mn2+ entry through a Ca2+ store-operated Ca2+ entry pathway (SOCP) were determined. While the temperature dependence of intracellular Ca2+ release, sequestration and extrusion (i.e. enzymatically controlled phenomena) were found to follow the same exponential function [t = A x e(-B x T); t, reaction time; A, B, constants; T, experimental temperature in K; K = degree C + 273], Ca2+/Mn2+ entry upon ion application to pre-stimulated cells strictly followed Fick's law of diffusion [t = A x (1/T) x e(B/T); t, reaction time; A, B, constants; T, experimental temperature in K]. In contrast to the temperature dependence of bradykinin-stimulated Ca2+/Mn2+ entry, the temperature dependence of Mn2+ entry on addition of agonist did not correlate with Fick's law of diffusion, but followed the same exponential function obtained for Ca2+ release, sequestration and extrusion. In conclusion, these data suggest that activation of SOCP by autacoid is due to enzymatic mechanism(s), while Ca2+ entry through SOCP, once activated, is due to a diffusion-like phenomenon.
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24
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Zhang L, Bradley ME, Buxton IL. Inositolpolyphosphate binding sites and their likely role in calcium regulation in smooth muscle. Int J Biochem Cell Biol 1995; 27:1231-48. [PMID: 8581820 DOI: 10.1016/1357-2725(95)00111-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- L Zhang
- Department of Pharmacology, University of Nevada School of Medicine, Reno 89557, USA
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25
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Poitras M, Ribeiro-Do-Valle RM, Poirier SN, Guillemette G. Bidirectional activity of the endoplasmic reticulum Ca(2+)-ATPase of bovine adrenal cortex. Biochemistry 1995; 34:9755-61. [PMID: 7626646 DOI: 10.1021/bi00030a013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
It is generally accepted that the ryanodine receptor and the inositol 1,4,5-trisphosphate receptor play major roles in the complex mechanisms by which agonists increase intracellular Ca2+ concentration. In these mechanisms, the endoplasmic reticulum Ca(2+)-ATPase has been attributed an accessory role of refilling the intracellular Ca2+ store. In the present study, the activity of the microsomal Ca(2+)-ATPase of bovine adrenal cortex was investigated. We show that the Ca(2+)-pumping activity of the Ca(2+)-ATPase is related to the ADP/ATP ratio. Our results also show that a brisk increase of the ADP/ATP ratio upon addition of exogenous ADP triggered a rapid release of Ca2+ from preloaded microsomes. ADP released Ca2+ in a dose-dependent manner with an EC50 of 2.98 +/- 0.78 mM. ADP-induced Ca2+ release was not prevented by heparin, ruling out the participation of the inositol 1,4,5-trisphosphate receptor. ADP-induced Ca2+ release could not be attributed to the mere inhibition of the Ca(2+)-ATPase, since the rate of ADP-induced Ca2+ release was 20 times faster than the rate of Ca2+ release induced by a maximal concentration of thapsigargin (2 microM). ADP-induced Ca2+ release experiments performed in the presence of [32P]PO4 revealed a concomitant production of [32P]ATP. ADP-induced [32P]ATP production was dose-dependent, with an EC50 of 5.50 +/- 0.70 mM. ADP-induced [32P]ATP production was prevented by ionomycin (10 microM) and by high concentrations of extramicrosomal Ca2+. These results demonstrate that the microsomal Ca(2+)-ATPase of adrenal cortex possesses a bidirectional activity that depends on ADP concentrations, the Ca2+ gradient across the microsomal membrane, and probably also ATP concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Poitras
- Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Québec, Canada
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26
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Kasschau MR, Byam-Smith MP, Gentry DS, Watson FN. Influence of pH and temperature on hemolysis by adult Schistosoma mansoni membranes. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1995; 271:315-22. [PMID: 7722474 DOI: 10.1002/jez.1402710409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Membrane fractions from homogenized adult Schistosoma mansoni are known to lyse host red blood cells (RBC's), which serve as an important nutrient source for the parasite. In order to learn more about the hemolytic process, we investigated the effects of pH and temperature on the steps involved in the hemolytic process. For maximum schistosome induced hemolysis to occur the worm lytic agent must be in contact with RBCs in a low pH (pH 5.1), high temperature (37 degrees C) environment for a short time (30 min), after which hemolysis occurs at both pH 7.5 and 5.1. At pH 7.5 the hemolytic process is relatively temperature independent and highly concentration dependent. Dose-response experiments suggest that a multi-hit process of hemolysis is probably involved. Temperature and dextran experiments suggest that a pore is formed in the RBC membrane at pH 7.5. At pH 5.1 hemolysis is temperature dependent and not very concentration dependent. Dose-response data suggest that a single-hit process of hemolysis is utilized at low pH. The hemolytic process at pH 7.5, the pH of the host blood, and pH 5.1, the approximate pH of the worm gut, appears to be very different.
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Affiliation(s)
- M R Kasschau
- Program in Biological Sciences, University of Houston-Clear Lake, Texas 77058
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27
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Davies RV, Yates DB. 4-quinolones as potential cardiovascular agents. PROGRESS IN MEDICINAL CHEMISTRY 1995; 32:115-55. [PMID: 8577917 DOI: 10.1016/s0079-6468(08)70453-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- R V Davies
- Boots Pharmaceuticals Research Department, Nottingham, UK
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28
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Ali N, Agrawal DK. Guanine nucleotide binding regulatory proteins: their characteristics and identification. J Pharmacol Toxicol Methods 1994; 32:187-96. [PMID: 7881132 DOI: 10.1016/1056-8719(94)90086-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Many biological signals are processed by the binding of chemicals to cell surface receptors. Signals are switched to intracellular language via guanine nucleotide binding regulatory proteins (G-proteins) which are present in all eukaryotic cells. Thus, G-proteins serve as interfaces between receptor-response coupling. Two forms of G-proteins have been reported: conventional G-proteins which are heterotrimeric and consist of alpha, beta, and gamma subunits, and monomeric small molecular weight G-proteins which are generally found as single polypeptides. Recently, high molecular weight G-proteins have also been described. The family of G-proteins contains multiple genes that encode the alpha, beta, or gamma subunits. G-proteins play a pivotal role in excitation-contraction coupling in smooth muscle function and control metabolic and secretory processes. In this review article, we have given a brief overview on the characteristics and methodology for the identification of G-proteins. The heterotrimeric G-proteins are generally identified by Western blotting and ADP-ribosylation with bacterial toxins. The monomeric and high molecular weight G-proteins have been identified by [35S]GTP delta S overlay technique and photoaffinity labeling, respectively. Recently, the use of molecular genetic probes has made it possible to investigate the expression of the message for various G-proteins.
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Affiliation(s)
- N Ali
- Department of Internal Medicine, Creighton University School of Medicine, Omaha, Nebraska 68178
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29
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Nakade S, Rhee S, Hamanaka H, Mikoshiba K. Cyclic AMP-dependent phosphorylation of an immunoaffinity-purified homotetrameric inositol 1,4,5-trisphosphate receptor (type I) increases Ca2+ flux in reconstituted lipid vesicles. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37437-9] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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30
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Bothmer J, Jolles J. Phosphoinositide metabolism, aging and Alzheimer's disease. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1225:111-24. [PMID: 8280779 DOI: 10.1016/0925-4439(94)90068-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- J Bothmer
- Department of Neuropsychology and Psychobiology, University of Limburg, Maastricht, The Netherlands
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31
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Blackwood AM, Bolton TB. Mechanism of carbachol-evoked contractions of guinea-pig ileal smooth muscle close to freezing point. Br J Pharmacol 1993; 109:1029-37. [PMID: 8401915 PMCID: PMC2175742 DOI: 10.1111/j.1476-5381.1993.tb13725.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
1. The effect of lowering the temperature to near freezing-point upon the contractions and [3H]-inositol phosphate responses to carbachol were investigated in longitudinal smooth muscle from the guinea-pig ileum. 2. The peak amplitude of the contraction to a single application of 100 microM carbachol was the same at 37 degrees C and temperatures near freezing-point. However, the sensitivity to carbachol was reduced upon lowering the temperature and the time to peak contraction was increased from 5-10 s to 2-10 min. Even when the temperature was maintained near freezing-point, washing off carbachol produced a relaxation and eventual return of tension to basal levels. 3. Incubating the tissue in 140 mM K+, calcium-free solution or in calcium channel antagonists significantly reduced the carbachol-induced contraction to 10-30% of the control at 37 degrees C and also at 3 degrees C. Thus the majority of the activator calcium required for contraction entered the tissue via voltage-dependent calcium channels (VDCs) at both 37 degrees C and 3 degrees C. 4. The contractions produced by high potassium solutions were less at temperatures close to freezing-point than those at 37 degrees C suggesting that voltage-dependent calcium entry was inhibited as the temperature was lowered. 5. A small part of the contractile response to 100 microM carbachol was resistant to the removal of extracellular calcium at both 37 degrees C and 3 degrees C and this component was increased under depolarizing conditions. This suggests that the release of stored calcium contributes to a minor degree to contraction at both 37 degrees C and 3 degrees C.6. Although 100 microM carbachol produced a statistically significant rise in several [3H]-inositol phosphate isomers at both 37 degrees C and 3 degrees C, the production of [3H]-inositol phosphates was less at 3 degrees C than at 37 degrees C and the increase in their production caused by carbachol was much slower.7. These results suggest that the carbachol-induced contraction at 3 degrees C utilizes both calcium entry through VDCs and calcium release from intracellular stores, as at 37 degrees C. The components of the responses dependent upon intracellular calcium release at 37 degrees C and at temperatures near freezing-point were similar. However, the production of [3H]-inositol phosphates, including the calcium-mobilizing second messenger inositol (1,4,5) trisphosphate (Ins(1,4,5)P3), is reduced at such low temperatures.
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Affiliation(s)
- A M Blackwood
- Department of Pharmacology and Clinical Pharmacology, St George's Hospital Medical School, London
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32
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Edwards E, Ashby CR, Wang RY. Further characterization of 5-HT- and 5-HT3 receptor agonists'-stimulated phosphoinositol phosphates accumulation. Brain Res 1993; 617:113-9. [PMID: 8397045 DOI: 10.1016/0006-8993(93)90620-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The calcium requirement for serotonin (5-HT)- and the 5-HT3 receptor agonists, 2-Me-5-HT- and PBG-dependent breakdown of phosphatidyl inositol has been examined in the rat fronto-cingulate cortex. The omission of added Ca2+ from the Kreb's incubation medium reduced the [3H]inositol phosphate accumulation from pre-labelled phospholipids. Removal of Ca2+ by pre-incubation with EGTA (0.5 mM), as well as the addition of the calcium channel blocker, lanthanum (10 microM), abolished the 5-HT- and the 5-HT3 receptor agonists'-stimulated phosphoinositide (PI) response. By contrast, the calcium ionophores, A 23187 and Ionomycin (both at 30 microM) stimulated PI hydrolysis, and this effect was additive to the increased PI turnover induced by 5-HT, 2-Me-5-HT and PBG. The increase in phosphoinositide hydrolysis induced by 5-HT and 2-Me-5-HT was significantly inhibited by phorbol dibutyrate (PDBu) and phorbol myristate acetate, indicating that the activation of protein kinase C (PKC) may provide negative feedback to the PI response induced by 5-HT and 2-Me-5-HT-stimulated PI metabolism was reversed by the PKC inhibitors, staurosporine, calphostin C and chelerythrine (all at 10 microM), however, Pertussis toxin (0.5 and 1 microgram) had no effect on either 5-HT's or 2-Me-5-HT's increased stimulation of PI hydrolysis, suggesting that this response is not associated to a Gi GTP binding protein.
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Affiliation(s)
- E Edwards
- Department of Pharmacology and Toxicology, University of Maryland, Baltimore 21201
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33
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Bezprozvanny I, Ehrlich BE. ATP modulates the function of inositol 1,4,5-trisphosphate-gated channels at two sites. Neuron 1993; 10:1175-84. [PMID: 7686381 DOI: 10.1016/0896-6273(93)90065-y] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The inositol 1,4,5-trisphosphate (IP3) receptor, a Ca(2+)-permeable channel, plays a key role in intracellular Ca2+ signaling. The effects of ATP on the IP3 receptor at the single-channel level were characterized after channel incorporation into planar lipid bilayers. ATP alone was not sufficient to open the IP3-gated channel, but addition of ATP or nonhydrolyzable ATP analogs in the presence of IP3 increased the frequency of channel openings 4.8-fold and increased the average duration of channel openings 2.5-fold; channel conductance was unchanged. High concentrations of ATP (> 4 mM) decreased channel activity most probably by competing with IP3-binding site. Allosteric modulation of IP3-induced Ca2+ release by ATP may contribute to the maintenance of cell viability during periods of energy starvation.
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MESH Headings
- Adenosine Triphosphate/analogs & derivatives
- Adenosine Triphosphate/pharmacology
- Animals
- Calcium/metabolism
- Calcium Channels
- Cerebellum/physiology
- Dogs
- Endoplasmic Reticulum/physiology
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate/pharmacology
- Inositol 1,4,5-Trisphosphate Receptors
- Ion Channel Gating/drug effects
- Ion Channel Gating/physiology
- Ion Channels/drug effects
- Ion Channels/physiology
- Kinetics
- Lipid Bilayers
- Mathematics
- Microsomes/physiology
- Models, Neurological
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/physiology
- Receptors, Cytoplasmic and Nuclear
- Signal Transduction/physiology
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Affiliation(s)
- I Bezprozvanny
- Department of Medicine, University of Connecticut, Farmington 06030
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34
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Lyu RM, Smith JB. Genistein inhibits calcium release by platelet-derived growth factor but not bradykinin or cadmium in human fibroblasts. Cell Biol Toxicol 1993; 9:141-8. [PMID: 8242430 DOI: 10.1007/bf00757576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cd2+ provokes inositol trisphosphate production and releases stored Ca2+, apparently by binding to a zinc site in the external domain of an orphan receptor. One microM Cd2+ evokes an immediate spike in cytosolic free Ca2+, which is similar to that evoked by bradykinin. Platelet-derived growth factor (PDGF) also increases free Ca2+ in human dermal fibroblasts, but there is a distinct lag before free Ca2+ rises in response to PDGF. Genistein, which selectively inhibits tyrosine kinases, markedly inhibited Ca2+ mobilization evoked by PDGF. Calcium mobilization triggered by cadmium or bradykinin was relatively insensitive to genistein. The PDGF receptor is known to be a tyrosine kinase, which phosphorylates and thereby activates phospholipase C gamma, whereas a G protein couples the bradykinin receptor to another phospholipase C isoform. These findings support the hypothesis that the orphan receptor triggered by cadmium is coupled to phospholipase C via a G protein.
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Affiliation(s)
- R M Lyu
- Department of Pharmacology, School of Medicine, University of Alabama at Birmingham 35294
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35
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Kinetics of Ca2+ release and contraction induced by photolysis of caged D-myo-inositol 1,4,5-trisphosphate in smooth muscle. The effects of heparin, procaine, and adenine nucleotides. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41672-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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36
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Missiaen L, De Smedt H, Droogmans G, Himpens B, Casteels R. Calcium ion homeostasis in smooth muscle. Pharmacol Ther 1992; 56:191-231. [PMID: 1297985 DOI: 10.1016/0163-7258(92)90017-t] [Citation(s) in RCA: 92] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ca2+ plays an important role in the regulation of smooth-muscle contraction. In this review, we will focus on the various Ca(2+)-transport processes that contribute to the cytosolic Ca2+ concentration. Mainly the functional aspects will be covered. The smooth-muscle inositol 1,4,5-trisphosphate receptor and ryanodine receptor will be extensively discussed. Smooth-muscle contraction also depends on extracellular Ca2+ and both voltage- and Ca(2+)-release-activated plasma-membrane Ca2+ channels will be reviewed. We will finally discuss some functional properties of the Ca2+ pumps that remove Ca2+ from the cytoplasm and of the Ca2+ regulation of the nucleus.
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Affiliation(s)
- L Missiaen
- Laboratorium voor Fysiologie, K. U. Leuven, Belgium
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37
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Shimamoto H, Kwan CY, Daniel EE. Pharmacological assessment of Ca2+ dependence of endothelin-1-induced response in rat aorta. Eur J Pharmacol 1992; 216:225-33. [PMID: 1397009 DOI: 10.1016/0014-2999(92)90364-a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In rat aorta, endothelin-1 (ET-1) induced a slowly developing and sustained contraction in Ca(2+)-containing normal Krebs, nominally Ca(2+)-free Krebs, and Ca(2+)-free Krebs containing EGTA with a decreasing level of contraction. When ET-1-precontracted tissues were washed with Ca(2+)-free Krebs +50 microM EGTA, the tissues spontaneously and slowly relaxed. Readministration of Ca2+ during the early spontaneous relaxation phase caused a rapidly developing tonic contraction. When added during the late spontaneous relaxation phase, Ca2+ evoked slowly developing or, sometimes, biphasic contractions. In the presence of sarcoplasmic reticulum Ca(2+)-pump inhibitor, cyclopiazonic acid, the above biphasic contraction brought about by readministration of Ca2+ converted to a rapidly developing monophasic response. Thus, the first component of the biphasic contraction may be due to refilling of ET-1-sensitive Ca2+ store via the internal membrane Ca(2+)-pump. Furthermore, the ability of the phenylephrine-sensitive pool of internal Ca2+ to refill in the presence of 10(-8) M ET-1 suggests that the phenylephrine-sensitive pool differs from ET-1-sensitive pool and cannot be depleted by ET-1.
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Affiliation(s)
- H Shimamoto
- Department of Biomedical Sciences, Faculty of Health Sciences, McMaster University, Hamilton, Ont., Canada
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38
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Luong TT, Poitras M, Boulay G, Guillemette G. Interaction of polyanions with the recognition sites for inositol 1,4,5-trisphosphate in the bovine adrenal cortex. Eur J Pharmacol 1991; 208:213-21. [PMID: 1663045 DOI: 10.1016/0922-4106(91)90098-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Inositol 1,4,5-trisphosphate (InsP3) serves as a second messenger for Ca2+ mobilization in a wide variety of cells. InsP3 activates a specific receptor/channel located on an internal Ca2+ store. Because heparin has already been shown to block the action of InsP3, we have looked at the influence of other polyanions (dextran sulfate and polyvinyl sulfate) on the action and metabolism of InsP3 in the bovine adrenal cortex. Polyvinyl sulfate blocked InsP3 binding to adrenal cortex microsomes with a half-maximal efficiency of 250 nM. Scatchard analyses revealed that this effect was not competitive. The Ca2+ releasing activity of InsP3 on the same microsomal preparation was monitored with the fluorescent indicator, fura-2. Polyvinyl sulfate blocked this activity with a half-maximal efficiency of 80 nM. The effect of polyvinyl sulfate could not be overcome by supramaximal doses of InsP3, suggesting a non-competitive inhibitory effect. The activity of InsP3 phosphatase from bovine adrenal cortex microsomes was also studied. Polyvinyl sulfate inhibited the activity of the phosphatase with a half-maximal efficiency of 5 microM. Lineweaver-Burk plots revealed that this effect was not competitive. Polyvinyl sulfate was able to inhibit the activity of InsP3 kinase from bovine adrenal cortex cytosol. The half-maximal dose was 15 nM and the Lineweaver-Burk analysis showed that the inhibition was not competitive. The effect of dextran sulfate 5000 (DS-5000) on these activities was also studied. DS-5000 inhibited in a competitive manner the binding of InsP3 to its receptor (IC50 of 34 microM), the release of Ca2+ induced by InsP3 (IC50 of 6.5 microM) and the activity of InsP3 phosphatase (IC50 of 57 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T T Luong
- Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Quebec, Canada
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39
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Koshiyama H, Tashjian AH. Evidence for multiple intracellular calcium pools in GH4C1 cells: investigations using thapsigargin. Biochem Biophys Res Commun 1991; 177:551-8. [PMID: 1645964 DOI: 10.1016/0006-291x(91)92019-g] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The actions of thapsigargin (Tg), a plant sesquiterpene lactone, on Ca2+ homeostasis were investigated in digitonin-permeabilized GH4C1 rat pituitary cells. Tg (1 microM) caused a rapid and sustained increase in ambient Ca2+ concentration [( Ca2+]) and inhibited the rise in [Ca2+] induced by subsequent addition of TRH (100 nM), inositol 1,4,5-trisphosphate (IP3, 10 microM), or the nonhydrolyzable GTP analogue guanosine 5'-0-(3-thiotriphosphate) (GTP gamma S, 10 microM). However, neither IP3 nor GTP gamma S pretreatment, which themselves release sequestered Ca2+, prevented the Ca2+ accumulation induced by Tg. Pretreatment with heparin (100 micrograms/ml, 10 min), an IP3 receptor antagonist, did not affect Ca2+ accumulation induced by Tg, although it abolished the rise in [Ca2+] induced by IP3. The ability of Tg to increase [Ca2+] was dependent on added ATP. We conclude that, in GH4C1 cells, Tg acts, in part, on TRH-, IP3- and GTP gamma S-sensitive Ca2+ pools; however, Tg also acts on an ATP-dependent pool of intracellular Ca2+ which is not sensitive to TRH, IP3 or GTP gamma S, indicating a complexity of intracellular Ca2+ pools not previously appreciated in these cells.
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Affiliation(s)
- H Koshiyama
- Laboratory of Toxicology, Harvard School of Public Health, Boston, MA
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40
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Affiliation(s)
- S L Linas
- University of Colorado School of Medicine, Denver
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41
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Somlyo AP, Kitazawa T, Kobayashi S, Gong MC, Somlyo AV. Pharmacomechanical coupling: the membranes talk to the crossbridges. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1991; 304:185-208. [PMID: 1803899 DOI: 10.1007/978-1-4684-6003-2_17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- A P Somlyo
- Department of Physiology, University of Virginia School of Medicine, Charlottesville 22908
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42
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Shuttleworth TJ, Thompson JL. Effect of temperature on receptor-activated changes in [Ca2+]i and their determination using fluorescent probes. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)52309-7] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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43
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Abstract
Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) is a soluble intracellular messenger formed rapidly after activation of a variety of cell-surface receptors that stimulate phosphoinositidase C activity. The initial response to Ins(1,4,5)P3 is a rapid Ca2+ efflux from nonmitochondrial intracellular stores which are probably specialized subcompartments of the endoplasmic reticulum, although their exact identities remain unknown. This initial response is followed by more complex Ca2+ signals: regenerative Ca2+ waves propagate across the cell, repetitive Ca2+ spikes occur, and stimulated Ca2+ entry across the plasma membrane contributes to the sustained Ca2+ signal. The mechanisms underlying these complex Ca2+ signals are unknown, although Ins(1,4,5)P3 is clearly involved. The intracellular receptor that mediates Ins(1,4,5)P3-stimulated Ca2+ mobilization has been purified and functionally reconstituted, and its amino acid sequence deduced from its cDNA sequence. These studies demonstrate that the Ins(1,4,5)P3 receptor has an integral Ca2+ channel separated from the Ins(1,4,5)P3 binding site by a long stretch of residues some of which form binding sites for allosteric regulators, and some of which are substrates for phosphorylation. In this review, we discuss the ligand recognition characteristics of Ins(1,4,5)P3 receptors, and their functional properties in their native environment and after purification, and we relate these properties to what is known of the structure of the receptor. In addition to regulation by Ins(1,4,5)P3, the Ins(1,4,5)P3 receptor is subject to many additional regulatory influences which include Ca2+, adenine nucleotides, pH and phosphorylation by protein kinases. Many of the functional and structural characteristics of the Ins(1,4,5)P3 receptor show striking similarities to another intracellular Ca2+ channel, the ryanodine receptor. These properties of the Ins(1,4,5)P3 are discussed, and their possible roles in contributing to the complex Ca2+ signals evoked by extracellular stimuli are considered.
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Affiliation(s)
- C W Taylor
- Department of Pharmacology, Cambridge, U.K
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44
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Maeda N, Kawasaki T, Nakade S, Yokota N, Taguchi T, Kasai M, Mikoshiba K. Structural and functional characterization of inositol 1,4,5-trisphosphate receptor channel from mouse cerebellum. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(17)35289-4] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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45
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Abstract
The intracellular nonmitochondrial calcium pools of saponin-permeabilized NG108-15 cells were characterized using inositol 1,4,5-trisphosphate (IP3) and GTP. IP3 or GTP alone induced release of 47 and 68%, respectively, of the calcium that was releasable by A23187. GTP induced release of a further 24% of the calcium after IP3 treatment, whereas IP3 induced release of a further 11% of the calcium after GTP treatment. Guanosine 5'-O-(3-thio)triphosphate had little effect on IP3-induced calcium release but completely inhibited GTP-induced calcium release. In contrast, heparin inhibited the action of IP3 but not that of GTP. The results imply the existence of at least three nonmitochondrial pools: (a) 31% is releasable by IP3 and GTP, (b) 11% is releasable by IP3 alone, and (c) 24% is releasable by GTP alone. GTP enhanced calcium uptake in the presence of oxalate with an EC50 of 0.6 microM and stimulated calcium release in the absence of oxalate with an EC50 of 0.32 microM. The similar EC50 values for these dual effects of GTP on calcium movement suggest that GTP exerts its dual action by the same mechanism.
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Affiliation(s)
- S H Chueh
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, R.O.C
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46
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Smith JB, Smith L. Energy dependence of sodium-calcium exchange in vascular smooth muscle cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1990; 259:C302-9. [PMID: 2382703 DOI: 10.1152/ajpcell.1990.259.2.c302] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Three different types of mitochondrial poisons (oligomycin, antimycin A, and dinitrophenol) strongly inhibited Na(+)-Ca2+ exchange in aortic myocytes. Exchange activity was assayed as 45Ca2+ uptake that depended on inverting the Na+ gradient and was inhibited by 25 microM dimethylbenzamil. Glucose markedly decreased the inhibition of exchange activity by these three poisons. Glucose also prevented rotenone from inhibiting exchange and depleting cellular ATP. In the absence of glucose, rotenone decreased ATP and exchange activity with half-times of 0.8 and 0.9 min, respectively. Almost eliminating cellular ATP with rotenone maximally inhibited exchange by 80%. Repletion of ATP with glucose substantially restored Na(+)-Ca2+ exchange activity. Ca2+ uptake by organelles, subsequent to entry via exchange for Na+, does not appear to contribute significantly to exchange activity as assayed in intact myocytes. The specific activity of Na(+)-Ca2+ exchange was approximately 30 nmol.min-1.mg protein-1. These findings suggest that ATP modulates exchange activity and that there are approximately 150,000 Na(+)-Ca2+ exchangers per cell, assuming that the turnover number is 1,000 s-1.
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Affiliation(s)
- J B Smith
- Department of Pharmacology, School of Medicine, University of Alabama, Birmingham 35294
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47
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Inositol 1,4,5-trisphosphate-triggered Ca2+ release from bovine adrenal medullary secretory vesicles. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)77367-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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48
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Guillemette G, Favreau I, Lamontagne S, Boulay G. 2,3-Diphosphoglycerate is a nonselective inhibitor of inositol 1,4,5-trisphosphate action and metabolism. Eur J Pharmacol 1990; 188:251-60. [PMID: 2163877 DOI: 10.1016/0922-4106(90)90009-m] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Inositol 1,4,5-trisphosphate (InsP3) is an important second messenger generated from the hydrolysis of phosphatidylinositol 4,5-bisphosphate by phospholipase C in response to Ca2(+)-mobilizing stimuli. InsP3 interacts with specific intracellular receptors and triggers the release of sequestered Ca2+ from an intracellular store. We have looked at the influence of 2,3-diphosphoglycerate on the action and metabolism of InsP3 in the bovine adrenal cortex. 2,3-Diphosphoglycerate blocked InsP3 binding to adrenal cortex microsomes with a half-maximal efficiency of 0.5 mM. Scatchard analyses revealed that 2,3-diphosphoglycerate did not change the maximal capacity of the microsomes, but decreased their binding affinity for InsP3. The Ca2(+)-releasing activity of InsP3 on the same microsomal preparation was monitored with the fluorescent indicator, Fura-2. 2,3-Diphosphoglycerate blocked this activity with a half-maximal efficiency of 2 mM. The effect of 2,3-diphosphoglycerate could be overcome by supramaximal doses of InsP3, indicating a competitive inhibitory effect. The activity of InsP3 phosphatase from bovine adrenal cortex microsomes was also studied. 2,3-Diphosphoglycerate inhibited the activity of the phosphatase with a half-maximal efficiency of 0.3 mM. Lineweaver-Burke plots revealed that this effect was competitive. Finally, 2,3-diphosphoglycerate was also able to inhibit the activity of a partially purified preparation of InsP3 kinase from bovine adrenal cortex cytosol. The half-maximal dose was around 10 mM and the Lineweaver-Burke plot showed that the inhibition was competitive. These results show that 2,3-diphosphoglycerate can be considered as a structural analog of InsP3. Its inhibitory effects, however, are not selective enough to use it as an InsP3 protective agent in Ca2(+)-mobilization studies.
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Affiliation(s)
- G Guillemette
- Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Quebec, Canada
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49
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Yamamoto H, Kanaide H. Release of intracellularly stored Ca2+ by inositol 1,4,5-trisphosphate--an overview. GENERAL PHARMACOLOGY 1990; 21:387-93. [PMID: 2199296 DOI: 10.1016/0306-3623(90)90686-g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
1. Inositol 1,4,5-trisphosphate (I(1,4,5)P3) releases Ca2+ from ATP-dependent Ca2+ stores in permeabilized cells and in microsomal fractions. 2. Various factors affect the amount of Ca2+ released by I(1,4,5)P3. 3. The molecular mechanism involved in the I(1,4,5)P3-induced Ca2+ release is now being investigated and I(1,4,5)P3-specific receptors and/or specific release channels are being given special attention. 4. While the I(1,4,5)P3-sensitive Ca2+ stores are presumed to locate at the endoplasmic reticulum, the relation between the I(1,4,5)P3- and the agonist-sensitive Ca2+ stores remains to be elucidated.
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Affiliation(s)
- H Yamamoto
- Medical Education Center, Kyushu University, Fukuoka, Japan
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50
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Williams JA, Burnham DB, Hootman SR. Cellular Regulation of Pancreatic Secretion. Compr Physiol 1989. [DOI: 10.1002/cphy.cp060321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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