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Campos J, Gleitze S, Hidalgo C, Núñez MT. IP 3R-Mediated Calcium Release Promotes Ferroptotic Death in SH-SY5Y Neuroblastoma Cells. Antioxidants (Basel) 2024; 13:196. [PMID: 38397794 PMCID: PMC10886377 DOI: 10.3390/antiox13020196] [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: 01/12/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
Ferroptosis is an iron-dependent cell death pathway that involves the depletion of intracellular glutathione (GSH) levels and iron-mediated lipid peroxidation. Ferroptosis is experimentally caused by the inhibition of the cystine/glutamate antiporter xCT, which depletes cells of GSH, or by inhibition of glutathione peroxidase 4 (GPx4), a key regulator of lipid peroxidation. The events that occur between GPx4 inhibition and the execution of ferroptotic cell death are currently a matter of active research. Previous work has shown that calcium release from the endoplasmic reticulum (ER) mediated by ryanodine receptor (RyR) channels contributes to ferroptosis-induced cell death in primary hippocampal neurons. Here, we used SH-SY5Y neuroblastoma cells, which do not express RyR channels, to test if calcium release mediated by the inositol 1,4,5-trisphosphate receptor (IP3R) channel plays a role in this process. We show that treatment with RAS Selective Lethal Compound 3 (RSL3), a GPx4 inhibitor, enhanced reactive oxygen species (ROS) generation, increased cytoplasmic and mitochondrial calcium levels, increased lipid peroxidation, and caused cell death. The RSL3-induced calcium signals were inhibited by Xestospongin B, a specific inhibitor of the ER-resident IP3R calcium channel, by decreasing IP3R levels with carbachol and by IP3R1 knockdown, which also prevented the changes in cell morphology toward roundness induced by RSL3. Intracellular calcium chelation by incubation with BAPTA-AM inhibited RSL3-induced calcium signals, which were not affected by extracellular calcium depletion. We propose that GPx4 inhibition activates IP3R-mediated calcium release in SH-SY5Y cells, leading to increased cytoplasmic and mitochondrial calcium levels, which, in turn, stimulate ROS production and induce lipid peroxidation and cell death in a noxious positive feedback cycle.
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Affiliation(s)
- Joaquín Campos
- Chica and Heinz Schaller Foundation, Institute for Anatomy and Cell Biology, University of Heidelberg, 69120 Heidelberg, Germany;
| | - Silvia Gleitze
- Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago 8380000, Chile; (S.G.); (C.H.)
| | - Cecilia Hidalgo
- Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago 8380000, Chile; (S.G.); (C.H.)
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago 8380000, Chile
- Physiology and Biophysics Program, Institute of Biomedical Sciences and Center for Exercise, Metabolism and Cancer Studies, Faculty of Medicine, Universidad de Chile, Santiago 8380000, Chile
| | - Marco T. Núñez
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago 7800024, Chile
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Sánchez Triviño CA, Landinez MP, Duran S, Gomez MDP, Nasi E. Modulation of Gq/PLC-Mediated Signaling by Acute Lithium Exposure. Front Cell Neurosci 2022; 16:838939. [PMID: 35242014 PMCID: PMC8885521 DOI: 10.3389/fncel.2022.838939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 01/27/2022] [Indexed: 11/13/2022] Open
Abstract
Although lithium has long been one of the most widely used pharmacological agents in psychiatry, its mechanisms of action at the cellular and molecular levels remain poorly understood. One of the targets of Li+ is the phosphoinositide pathway, but whereas the impact of Li+ on inositol lipid metabolism is well documented, information on physiological effects at the cellular level is lacking. We examined in two mammalian cell lines the effect of acute Li+ exposure on the mobilization of internal Ca2+ and phospholipase C (PLC)-dependent membrane conductances. We first corroborated by Western blots and immunofluorescence in HEK293 cells the presence of key signaling elements of a muscarinic PLC pathway (M1AchR, Gq, PLC-β1, and IP3Rs). Stimulation with carbachol evoked a dose-dependent mobilization of Ca, as determined with fluorescent indicators. This was due to release from internal stores and proved susceptible to the PLC antagonist U73122. Li+ exposure reproducibly potentiated the Ca response in a concentration-dependent manner extending to the low millimolar range. To broaden those observations to a neuronal context and probe potential Li modulation of electrical signaling, we next examined the cell line SHsy5y. We replicated the potentiating effects of Li on the mobilization of internal Ca, and, after characterizing the basic properties of the electrical response to cholinergic stimulation, we also demonstrated an equally robust upregulation of muscarinic membrane currents. Finally, by directly stimulating the signaling pathway at different links downstream of the receptor, the site of action of the observed Li effects could be narrowed down to the G protein and its interaction with PLC-β. These observations document a modulation of Gq/PLC/IP3-mediated signaling by acute exposure to lithium, reflected in distinct physiological changes in cellular responses.
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Affiliation(s)
- Cesar Adolfo Sánchez Triviño
- Departamento de Biología, Universidad Nacional de Colombia, Bogotá, Colombia
- Centro Internacional de Física, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Maria Paula Landinez
- Departamento de Biología, Universidad Nacional de Colombia, Bogotá, Colombia
- Centro Internacional de Física, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Sara Duran
- Departamento de Biología, Universidad Nacional de Colombia, Bogotá, Colombia
- Centro Internacional de Física, Universidad Nacional de Colombia, Bogotá, Colombia
| | - María Del Pilar Gomez
- Departamento de Biología, Universidad Nacional de Colombia, Bogotá, Colombia
- Marine Biological Laboratory, Woods Hole, MA, United States
| | - Enrico Nasi
- Marine Biological Laboratory, Woods Hole, MA, United States
- Instituto de Genética, Universidad Nacional de Colombia, Bogotá, Colombia
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Arige V, Terry LE, Malik S, Knebel TR, Wagner II LE, Yule DI. CREB regulates the expression of type 1 inositol 1,4,5-trisphosphate receptors. J Cell Sci 2021; 134:jcs258875. [PMID: 34533188 PMCID: PMC8601716 DOI: 10.1242/jcs.258875] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/13/2021] [Indexed: 12/16/2022] Open
Abstract
Inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) play a central role in regulating intracellular Ca2+ signals in response to a variety of internal and external cues. Dysregulation of IP3R signaling is the underlying cause for numerous pathological conditions. It is well established that the activities of IP3Rs are governed by several post-translational modifications, including phosphorylation by protein kinase A (PKA). However, the long-term effects of PKA activation on expression of IP3R subtypes remains largely unexplored. In this report, we investigate the effects of chronic stimulation and tonic activity of PKA on the expression of IP3R subtypes. We demonstrate that expression of the type 1 IP3R (IP3R1) is augmented upon prolonged activation of PKA or upon ectopic overexpression of cyclic AMP-response element-binding protein (CREB) without altering IP3R2 and IP3R3 abundance. By contrast, inhibition of PKA or blocking CREB diminished IP3R1 expression. We also demonstrate that agonist-induced Ca2+-release mediated by IP3R1 is significantly attenuated upon blocking of CREB. Moreover, CREB - by regulating the expression of KRAS-induced actin-interacting protein (KRAP) - ensures correct localization and licensing of IP3R1. Overall, we report a crucial role for CREB in governing both the expression and correct localization of IP3R1. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
| | | | | | | | | | - David I. Yule
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
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Mitochondria and calcium defects correlate with axonal dysfunction in GDAP1-related Charcot-Marie-Tooth mouse model. Neurobiol Dis 2021; 152:105300. [PMID: 33582224 DOI: 10.1016/j.nbd.2021.105300] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/04/2021] [Accepted: 02/09/2021] [Indexed: 12/14/2022] Open
Abstract
Ganglioside-induced differentiation associated protein 1 (GDAP1) gene encodes a protein of the mitochondrial outer membrane and of the mitochondrial membrane contacts with the endoplasmic reticulum (MAMs) and lysosomes. Since mutations in GDAP1 cause Charcot-Marie-Tooth, an inherited motor and sensory neuropathy, its function is essential for peripheral nerve physiology. Our previous studies showed structural and functional defects in mitochondria and their contacts when GDAP1 is depleted. Nevertheless, the underlying axonal pathophysiological events remain unclear. Here, we have used embryonic motor neurons (eMNs) cultures from Gdap1 knockout (Gdap1-/-) mice to investigate in vivo mitochondria and calcium homeostasis in the axons. We imaged mitochondrial axonal transport and we found a defective pattern in the Gdap1-/- eMNs. We also detected pathological and functional mitochondria membrane abnormalities with a drop in ATP production and a deteriorated bioenergetic status. Another consequence of the loss of GDAP1 in the soma and axons of eMNs was the in vivo increase calcium levels in both basal conditions and during recovery after neuronal stimulation with glutamate. Further, we found that glutamate-stimulation of respiration was lower in Gdap1-/- eMNs showing that the basal bioenergetics failure jeopardizes a full respiratory response and prevents a rapid return of calcium to basal levels. Together, our results demonstrate that the loss of GDAP1 critically compromises the morphology and function of mitochondria and its relationship with calcium homeostasis in the soma and axons, offering important insight into the cellular mechanisms associated with axonal degeneration of GDAP1-related CMT neuropathies and the relevance that axon length may have.
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Mound A, Vautrin-Glabik A, Foulon A, Botia B, Hague F, Parys JB, Ouadid-Ahidouch H, Rodat-Despoix L. Downregulation of type 3 inositol (1,4,5)-trisphosphate receptor decreases breast cancer cell migration through an oscillatory Ca 2+ signal. Oncotarget 2017; 8:72324-72341. [PMID: 29069790 PMCID: PMC5641133 DOI: 10.18632/oncotarget.20327] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/04/2017] [Indexed: 01/02/2023] Open
Abstract
Breast cancer remains a research priority due to its invasive phenotype. Although the role of ion channels in cancer is now well established, the role of inositol (1,4,5)-trisphosphate (IP3) receptors (IP3Rs) remains enigmatic. If the three IP3Rs subtypes expression have been identified in various cancers, little is known about their physiological role. Here, we investigated the involvement of IP3R type 3 (IP3R3) in the migration processes of three human breast cancer cell lines showing different migration velocities: the low-migrating MCF-7 and the highly migrating and invasive MDA-MB-231 and MDA-MB-435S cell lines. We show that a higher IP3R3 expression level, but not IP3R1 nor IP3R2, is correlated to a stronger cell line migration capacity and a sustained calcium signal. Interestingly, silencing of IP3R3 highlights an oscillating calcium signaling profile and leads to a significant decrease of cell migration capacities of the three breast cancer cell lines. Conversely, stable overexpression of IP3R3 in MCF-7 cells significantly increases their migration capacities. This effect is completely reversed by IP3R3 silencing. In conclusion, we demonstrate that IP3R3 expression level increases the migration capacity of human breast cancer cells by changing the calcium signature.
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Affiliation(s)
- Abdallah Mound
- Laboratory of Cellular and Molecular Physiology (EA-4667), "Ion Channels in Breast Cancer", SFR CAP-SANTE (FED-4231), University of Amiens, UFR Sciences, 80039 Amiens, France
| | - Alexia Vautrin-Glabik
- Laboratory of Cellular and Molecular Physiology (EA-4667), "Ion Channels in Breast Cancer", SFR CAP-SANTE (FED-4231), University of Amiens, UFR Sciences, 80039 Amiens, France
| | - Arthur Foulon
- Laboratory of Cellular and Molecular Physiology (EA-4667), "Ion Channels in Breast Cancer", SFR CAP-SANTE (FED-4231), University of Amiens, UFR Sciences, 80039 Amiens, France
| | - Béatrice Botia
- Laboratory of Cellular and Molecular Physiology (EA-4667), "Ion Channels in Breast Cancer", SFR CAP-SANTE (FED-4231), University of Amiens, UFR Sciences, 80039 Amiens, France
| | - Frédéric Hague
- Laboratory of Cellular and Molecular Physiology (EA-4667), "Ion Channels in Breast Cancer", SFR CAP-SANTE (FED-4231), University of Amiens, UFR Sciences, 80039 Amiens, France
| | - Jan B Parys
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Campus Gasthuisberg O/N1- bus 802-K U Leuven, B-3000 Leuven, Belgium
| | - Halima Ouadid-Ahidouch
- Laboratory of Cellular and Molecular Physiology (EA-4667), "Ion Channels in Breast Cancer", SFR CAP-SANTE (FED-4231), University of Amiens, UFR Sciences, 80039 Amiens, France
| | - Lise Rodat-Despoix
- Laboratory of Cellular and Molecular Physiology (EA-4667), "Ion Channels in Breast Cancer", SFR CAP-SANTE (FED-4231), University of Amiens, UFR Sciences, 80039 Amiens, France
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Nakajima A, Tsuji M, Inagaki M, Tamura Y, Kato M, Niiya A, Usui Y, Oguchi K. Neuroprotective effects of propofol on ER stress-mediated apoptosis in neuroblastoma SH-SY5Y cells. Eur J Pharmacol 2014; 725:47-54. [DOI: 10.1016/j.ejphar.2014.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 12/20/2013] [Accepted: 01/07/2014] [Indexed: 11/27/2022]
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Pla-Martín D, Rueda CB, Estela A, Sánchez-Piris M, González-Sánchez P, Traba J, de la Fuente S, Scorrano L, Renau-Piqueras J, Alvarez J, Satrústegui J, Palau F. Silencing of the Charcot-Marie-Tooth disease-associated gene GDAP1 induces abnormal mitochondrial distribution and affects Ca2+ homeostasis by reducing store-operated Ca2+ entry. Neurobiol Dis 2013; 55:140-51. [PMID: 23542510 DOI: 10.1016/j.nbd.2013.03.010] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 03/04/2013] [Accepted: 03/19/2013] [Indexed: 11/25/2022] Open
Abstract
GDAP1 is an outer mitochondrial membrane protein that acts as a regulator of mitochondrial dynamics. Mutations of the GDAP1 gene cause Charcot-Marie-Tooth (CMT) neuropathy. We show that GDAP1 interacts with the vesicle-organelle trafficking proteins RAB6B and caytaxin, which suggests that GDAP1 may participate in the mitochondrial movement within the cell. GDAP1 silencing in the SH-SY5Y cell line induces abnormal distribution of the mitochondrial network, reduces the contact between mitochondria and endoplasmic reticulum (ER) and alters the mobilization of mitochondria towards plasma membrane upon depletion of ER-Ca(2+) stores. GDAP1 silencing does not affect mitochondrial Ca(2+) uptake, ER-Ca(2+), or Ca(2+) flow from ER to mitochondria, but reduces Ca(2+) inflow through store-operated Ca(2+) entry (SOCE) following mobilization of ER-Ca(2+) and SOCE-driven Ca(2+) entry in mitochondria. Our studies suggest that the pathophysiology of GDAP1-related CMT neuropathies may be associated with abnormal distribution and movement of mitochondria throughout cytoskeleton towards the ER and subplasmalemmal microdomains, resulting in a decrease in SOCE activity and impaired SOCE-driven Ca(2+) uptake in mitochondria.
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Affiliation(s)
- David Pla-Martín
- Laboratory of Genetics and Molecular Medicine, Instituto de Biomedicina de Valencia, CSIC, Valencia, Spain
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Thurley K, Smith IF, Tovey SC, Taylor CW, Parker I, Falcke M. Timescales of IP(3)-evoked Ca(2+) spikes emerge from Ca(2+) puffs only at the cellular level. Biophys J 2012; 101:2638-44. [PMID: 22261051 DOI: 10.1016/j.bpj.2011.10.030] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 09/29/2011] [Accepted: 10/03/2011] [Indexed: 10/14/2022] Open
Abstract
The behavior of biological systems is determined by the properties of their component molecules, but the interactions are usually too complex to understand fully how molecular behavior generates cellular behavior. Ca(2+) signaling by inositol trisphosphate receptors (IP(3)R) offers an opportunity to understand this relationship because the cellular behavior is defined largely by Ca(2+)-mediated interactions between IP(3)R. Ca(2+) released by a cluster of IP(3)R (giving a local Ca(2+) puff) diffuses and ignites the behavior of neighboring clusters (to give repetitive global Ca(2+) spikes). We use total internal reflection fluorescence microscopy of two mammalian cell lines to define the temporal relationships between Ca(2+) puffs (interpuff intervals, IPI) and Ca(2+) spikes (interspike intervals) evoked by flash photolysis of caged IP(3). We find that IPI are much shorter than interspike intervals, that puff activity is stochastic with a recovery time that is much shorter than the refractory period of the cell, and that IPI are not periodic. We conclude that Ca(2+) spikes do not arise from oscillatory dynamics of IP(3)R clusters, but that repetitive Ca(2+) spiking with its longer timescales is an emergent property of the dynamics of the whole cluster array.
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Affiliation(s)
- Kevin Thurley
- Mathematical Cell Physiology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.
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Smith IF, Wiltgen SM, Shuai J, Parker I. Ca(2+) puffs originate from preestablished stable clusters of inositol trisphosphate receptors. Sci Signal 2009; 2:ra77. [PMID: 19934435 PMCID: PMC2897231 DOI: 10.1126/scisignal.2000466] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Intracellular calcium ion (Ca(2+)) signaling crucially depends on the clustered organization of inositol trisphosphate receptors (IP(3)Rs) in the endoplasmic reticulum (ER) membrane. These ligand-gated ion channels liberate Ca(2+) to generate local signals known as Ca(2+) puffs. We tested the hypothesis that IP(3) itself elicits rapid clustering of IP(3)Rs by using flash photolysis of caged IP(3) in conjunction with high-resolution Ca(2+) imaging to monitor the activity and localization of individual IP(3)Rs within intact mammalian cells. Our results indicate that Ca(2+) puffs arising with latencies as short as 100 to 200 ms after photorelease of IP(3) already involve at least four IP(3)R channels, and that this number does not subsequently grow. Moreover, single active IP(3)Rs show limited mobility, and stochastic simulations suggest that aggregation of IP(3)Rs at puff sites by a diffusional trapping mechanism would require many seconds. We thus conclude that puff sites represent preestablished, stable clusters of IP(3)Rs and that functional IP(3)Rs are not readily diffusible within the ER membrane.
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Affiliation(s)
- Ian F Smith
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-4550, USA.
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Smith IF, Wiltgen SM, Parker I. Localization of puff sites adjacent to the plasma membrane: functional and spatial characterization of Ca2+ signaling in SH-SY5Y cells utilizing membrane-permeant caged IP3. Cell Calcium 2008; 45:65-76. [PMID: 18639334 DOI: 10.1016/j.ceca.2008.06.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 05/30/2008] [Accepted: 06/05/2008] [Indexed: 01/14/2023]
Abstract
The Xenopus oocyte has been a favored model system in which to study spatio-temporal mechanisms of intracellular Ca2+ dynamics, in large part because this giant cell facilitates intracellular injections of Ca2+ indicator dyes, buffers and caged compounds. However, the recent commercial availability of membrane-permeant ester forms of caged IP3 (ci-IP3) and EGTA, now allows for facile loading of these compounds into smaller mammalian cells, permitting control of [IP3]i and cytosolic Ca2+ buffering. Here, we establish the human neuroblastoma SH-SY5Y cell line as an advantageous experimental system for imaging Ca2+ signaling, and characterize IP3-mediated Ca2+ signaling mechanisms in these cells. Flash photo-release of increasing amounts of i-IP3 evokes Ca2+ puffs that transition to waves, but intracellular loading of EGTA decouples release sites, allowing discrete puffs to be studied over a wide range of [IP3]. Puff activity persists for minutes following a single photo-release, pointing to a slow rate of i-IP3 turnover in these cells and suggesting that repetitive Ca2+ spikes with periods of 20-30s are not driven by oscillations in [IP3]. Puff amplitudes are independent of [IP3], whereas their frequencies increase with increasing photo-release. Puff sites in SH-SY5Y cells are not preferentially localized near the nucleus, but instead are concentrated close to the plasma membrane where they can be visualized by total internal reflection microscopy, offering the potential for unprecedented spatio-temporal resolution of Ca2+ puff kinetics.
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Affiliation(s)
- Ian F Smith
- Department of Neurobiology and Behavior, University of California, 1146 McGaugh Hall, Irvine, CA 92697-4545, United States.
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Hattori M, Suzuki AZ, Higo T, Miyauchi H, Michikawa T, Nakamura T, Inoue T, Mikoshiba K. Distinct Roles of Inositol 1,4,5-Trisphosphate Receptor Types 1 and 3 in Ca2+ Signaling. J Biol Chem 2004; 279:11967-75. [PMID: 14707143 DOI: 10.1074/jbc.m311456200] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Three subtypes of inositol 1,4,5-trisphosphate receptor (IP(3)R1, IP(3)R2, and IP(3)R3) Ca(2+) release channel share basic properties but differ in terms of regulation. To what extent they contribute to complex Ca(2+) signaling, such as Ca(2+) oscillations, remains largely unknown. Here we show that HeLa cells express comparable amounts of IP(3)R1 and IP(3)R3, but knockdown by RNA interference of each subtype results in dramatically distinct Ca(2+) signaling patterns. Knockdown of IP(3)R1 significantly decreases total Ca(2+) signals and terminates Ca(2+) oscillations. Conversely, knockdown of IP(3)R3 leads to more robust and long lasting Ca(2+) oscillations than in controls. Effects of IP(3)R3 knockdown are surprisingly similar in COS-7 cells that predominantly (>90% of total IP(3)R) express IP(3)R3, suggesting that IP(3)R3 functions as an anti-Ca(2+)-oscillatory unit without contributing to peak amplitude of Ca(2+) signals, irrespective of its relative expression level. Therefore, differential expression of the IP(3)R subtype is critical for various forms of Ca(2+) signaling, and, particularly, IP(3)R1 and IP(3)R3 have opposite roles in generating Ca(2+) oscillations.
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Affiliation(s)
- Mitsuharu Hattori
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, 4-1-8, Hon-machi, Kawaguchi, Saitama 332-0012, Japan.
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Nakayama T, Hattori M, Uchida K, Nakamura T, Tateishi Y, Bannai H, Iwai M, Michikawa T, Inoue T, Mikoshiba K. The regulatory domain of the inositol 1,4,5-trisphosphate receptor is necessary to keep the channel domain closed: possible physiological significance of specific cleavage by caspase 3. Biochem J 2004; 377:299-307. [PMID: 12968951 PMCID: PMC1223858 DOI: 10.1042/bj20030599] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2003] [Revised: 08/27/2003] [Accepted: 09/12/2003] [Indexed: 11/17/2022]
Abstract
The type 1 inositol 1,4,5-trisphosphate receptor (IP(3)R1) is an intracellular Ca(2+) channel protein that plays crucial roles in generating complex Ca(2+) signalling patterns. IP(3)R1 consists of three domains: a ligand-binding domain, a regulatory domain and a channel domain. In order to investigate the function of these domains in its gating machinery and the physiological significance of specific cleavage by caspase 3 that is observed in cells undergoing apoptosis, we utilized various IP(3)R1 constructs tagged with green fluorescent protein (GFP). Expression of GFP-tagged full-length IP(3)R1 or IP(3)R1 lacking the ligand-binding domain in HeLa and COS-7 cells had little effect on cells' responsiveness to an IP(3)-generating agonist ATP and Ca(2+) leak induced by thapsigargin. On the other hand, in cells expressing the caspase-3-cleaved form (GFP-IP(3)R1-casp) or the channel domain alone (GFP-IP(3)R1-ES), both ATP and thapsigargin failed to induce increase of cytosolic Ca(2+) concentration. Interestingly, store-operated (-like) Ca(2+) entry was normally observed in these cells, irrespective of thapsigargin pre-treatment. These findings indicate that the Ca(2+) stores of cells expressing GFP-IP(3)R1-casp or GFP-IP(3)R1-ES are nearly empty in the resting state and that these proteins continuously leak Ca(2+). We therefore propose that the channel domain of IP(3)R1 tends to remain open and that the large regulatory domain of IP(3)R1 is necessary to keep the channel domain closed. Thus cleavage of IP(3)R1 by caspase 3 may contribute to the increased cytosolic Ca(2+) concentration often observed in cells undergoing apoptosis. Finally, GFP-IP(3)R1-casp or GFP-IP(3)R1-ES can be used as a novel tool to deplete intracellular Ca(2+) stores.
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Affiliation(s)
- Tomohiro Nakayama
- Division of Molecular Neurobiology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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