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Jardin I, Alvarado S, Sanchez-Collado J, Nieto-Felipe J, Lopez JJ, Salido GM, Rosado JA. Functional differences in agonist-induced plasma membrane expression of Orai1α and Orai1β. J Cell Physiol 2023; 238:2050-2062. [PMID: 37332264 DOI: 10.1002/jcp.31055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 04/20/2023] [Accepted: 05/24/2023] [Indexed: 06/20/2023]
Abstract
Orai1 is the pore-forming subunit of the store-operated Ca2+ release-activated Ca2+ (CRAC) channels involved in a variety of cellular functions. Two Orai1 variants have been identified, the long form, Orai1α, containing 301 amino acids, and the short form, Orai1β, which arises from alternative translation initiation from methionines 64 or 71, in Orai1α. Orai1 is mostly expressed in the plasma membrane, but a subset of Orai1 is located in intracellular compartments. Here we show that Ca2+ store depletion leads to trafficking and insertion of compartmentalized Orai1α in the plasma membrane via a mechanism that is independent on changes in cytosolic free-Ca2+ concentration, as demonstrated by cell loading with the fast intracellular Ca2+ chelator dimethyl BAPTA in the absence of extracellular Ca2+ . Interestingly, thapsigargin (TG) was found to be unable to induce translocation of Orai1β to the plasma membrane when expressed individually; by contrast, when Orai1β is co-expressed with Orai1α, cell treatment with TG induced rapid trafficking and insertion of compartmentalized Orai1β in the plasma membrane. Translocation of Orai1 forms to the plasma membrane was found to require the integrity of the actin cytoskeleton. Finally, expression of a dominant negative mutant of the small GTPase ARF6, and ARF6-T27N, abolished the translocation of compartmentalized Orai1 variants to the plasma membrane upon store depletion. These findings provide new insights into the mechanism that regulate the plasma membrane abundance of Orai1 variants after Ca2+ store depletion.
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Affiliation(s)
- Isaac Jardin
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Sandra Alvarado
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Jose Sanchez-Collado
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Joel Nieto-Felipe
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Jose J Lopez
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Gines M Salido
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Juan A Rosado
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
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Nieto-Felipe J, Sanchez-Collado J, Jardin I, Salido GM, Lopez JJ, Rosado JA. The store-operated Ca(2+) channel Orai1α is required for agonist-evoked NF-κB activation by a mechanism dependent on PKCβ2. J Biol Chem 2023; 299:102882. [PMID: 36623731 DOI: 10.1016/j.jbc.2023.102882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 12/30/2022] [Accepted: 12/31/2022] [Indexed: 01/09/2023] Open
Abstract
Store-operated Ca2+ entry is a ubiquitous mechanism for Ca2+ influx in mammalian cells that regulates a variety of physiological processes. The identification of two forms of Orai1, the predominant store-operated channel, Orai1α and Orai1β, raises the question whether they differentially regulate cell function. Orai1α is the full-length Orai1, containing 301 amino acids, whereas Orai1β lacks the N-terminal 63 amino acids. Here, using a combination of biochemistry and imaging combined with the use of human embryonic kidney 293 KO cells, missing the native Orai1, transfected with plasmids encoding for either Orai1α or Orai1β, we show that Orai1α plays a relevant role in agonist-induced NF-κB transcriptional activity. In contrast, functional Orai1β is not required for the activation of these transcription factors. The role of Orai1α in the activation of NF-κB is entirely dependent on Ca2+ influx and involves PKCβ activation. Our results indicate that Orai1α interacts with PKCβ2 by a mechanism involving the Orai1α exclusive AKAP79 association region, which strongly suggests a role for AKAP79 in this process. These findings provide evidence of the role of Orai1α in agonist-induced NF-κB transcriptional activity and reveal functional differences between Orai1 variants.
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Jardin I, Berna-Erro A, Nieto-Felipe J, Macias A, Sanchez-Collado J, Lopez JJ, Salido GM, Rosado JA. Similarities and Differences between the Orai1 Variants: Orai1α and Orai1β. Int J Mol Sci 2022; 23:ijms232314568. [PMID: 36498894 PMCID: PMC9735889 DOI: 10.3390/ijms232314568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 11/16/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022] Open
Abstract
Orai1, the first identified member of the Orai protein family, is ubiquitously expressed in the animal kingdom. Orai1 was initially characterized as the channel responsible for the store-operated calcium entry (SOCE), a major mechanism that allows cytosolic calcium concentration increments upon receptor-mediated IP3 generation, which results in intracellular Ca2+ store depletion. Furthermore, current evidence supports that abnormal Orai1 expression or function underlies several disorders. Orai1 is, together with STIM1, the key element of SOCE, conducting the Ca2+ release-activated Ca2+ (CRAC) current and, in association with TRPC1, the store-operated Ca2+ (SOC) current. Additionally, Orai1 is involved in non-capacitative pathways, as the arachidonate-regulated or LTC4-regulated Ca2+ channel (ARC/LRC), store-independent Ca2+ influx activated by the secretory pathway Ca2+-ATPase (SPCA2) and the small conductance Ca2+-activated K+ channel 3 (SK3). Furthermore, Orai1 possesses two variants, Orai1α and Orai1β, the latter lacking 63 amino acids in the N-terminus as compared to the full-length Orai1α form, which confers distinct features to each variant. Here, we review the current knowledge about the differences between Orai1α and Orai1β, the implications of the Ca2+ signals triggered by each variant, and their downstream modulatory effect within the cell.
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Sanchez-Collado J, Lopez JJ, Jardin I, Berna-Erro A, Camello PJ, Cantonero C, Smani T, Salido GM, Rosado JA. Orai1α, but not Orai1β, co-localizes with TRPC1 and is required for its plasma membrane location and activation in HeLa cells. Cell Mol Life Sci 2022; 79:33. [PMID: 34988680 PMCID: PMC8732813 DOI: 10.1007/s00018-021-04098-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/02/2021] [Accepted: 12/15/2021] [Indexed: 12/15/2022]
Abstract
The identification of two variants of the canonical pore-forming subunit of the Ca2+ release-activated Ca2+ (CRAC) channel Orai1, Orai1α and Orai1β, in mammalian cells arises the question whether they exhibit different functional characteristics. Orai1α and Orai1β differ in the N-terminal 63 amino acids, exclusive of Orai1α, and show different sensitivities to Ca2+-dependent inactivation, as well as distinct ability to form arachidonate-regulated channels. We have evaluated the role of both Orai1 variants in the activation of TRPC1 in HeLa cells. We found that Orai1α and Orai1β are required for the maintenance of regenerative Ca2+ oscillations, while TRPC1 plays a role in agonist-induced Ca2+ influx but is not essential for Ca2+ oscillations. Using APEX2 proximity labeling, co-immunoprecipitation and the fluorescence of G-GECO1.2 fused to Orai1α our results indicate that agonist stimulation and Ca2+ store depletion enhance Orai1α–TRPC1 interaction. Orai1α is essential for TRPC1 plasma membrane location and activation. Thus, TRPC1 function in HeLa cells depends on Ca2+ influx through Orai1α exclusively.
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Affiliation(s)
- Jose Sanchez-Collado
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, 10003, Caceres, Spain
| | - Jose J Lopez
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, 10003, Caceres, Spain.
| | - Isaac Jardin
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, 10003, Caceres, Spain
| | - Alejandro Berna-Erro
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, 10003, Caceres, Spain
| | - Pedro J Camello
- Department of Physiology, (Smooth Muscle Physiology Research Group), Institute of Molecular Pathology Biomarkers, University of Extremadura, 10003, Caceres, Spain
| | - Carlos Cantonero
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, 10003, Caceres, Spain
| | - Tarik Smani
- Department of Medical Physiology and Biophysics, University of Seville, Seville, Spain.,Group of Cardiovascular Pathophysiology, Institute of Biomedicine of Seville, University Hospital of Virgen del Rocio/University of Seville/CSIC, Seville, Spain
| | - Gines M Salido
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, 10003, Caceres, Spain
| | - Juan A Rosado
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, 10003, Caceres, Spain.
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