1
|
Narayanasamy S, Ong HL, Ambudkar IS. A Deep Dive into the N-Terminus of STIM Proteins: Structure-Function Analysis and Evolutionary Significance of the Functional Domains. Biomolecules 2024; 14:1200. [PMID: 39456133 PMCID: PMC11506743 DOI: 10.3390/biom14101200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2024] [Revised: 09/17/2024] [Accepted: 09/18/2024] [Indexed: 10/28/2024] Open
Abstract
Calcium is an important second messenger that is involved in almost all cellular processes. Disruptions in the regulation of intracellular Ca2+ levels ([Ca2+]i) adversely impact normal physiological function and can contribute to various diseased conditions. STIM and Orai proteins play important roles in maintaining [Ca2+]i through store-operated Ca2+ entry (SOCE), with STIM being the primary regulatory protein that governs the function of Orai channels. STIM1 and STIM2 are single-pass ER-transmembrane proteins with their N- and C-termini located in the ER lumen and cytoplasm, respectively. The N-terminal EF-SAM domain of STIMs senses [Ca2+]ER changes, while the C-terminus mediates clustering in ER-PM junctions and gating of Orai1. ER-Ca2+ store depletion triggers activation of the STIM proteins, which involves their multimerization and clustering in ER-PM junctions, where they recruit and activate Orai1 channels. In this review, we will discuss the structure, organization, and function of EF-hand motifs and the SAM domain of STIM proteins in relation to those of other eukaryotic proteins.
Collapse
Affiliation(s)
| | | | - Indu S. Ambudkar
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-1190, USA; (S.N.); (H.L.O.)
| |
Collapse
|
2
|
Sallinger M, Humer C, Ong HL, Narayanasamy S, Lin QT, Fahrner M, Grabmayr H, Berlansky S, Choi S, Schmidt T, Maltan L, Atzgerstorfer L, Niederwieser M, Frischauf I, Romanin C, Stathopulos PB, Ambudkar I, Leitner R, Bonhenry D, Schindl R. Essential role of N-terminal SAM regions in STIM1 multimerization and function. Proc Natl Acad Sci U S A 2024; 121:e2318874121. [PMID: 38753510 PMCID: PMC11127010 DOI: 10.1073/pnas.2318874121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 04/11/2024] [Indexed: 05/18/2024] Open
Abstract
The single-pass transmembrane protein Stromal Interaction Molecule 1 (STIM1), located in the endoplasmic reticulum (ER) membrane, possesses two main functions: It senses the ER-Ca2+ concentration and directly binds to the store-operated Ca2+ channel Orai1 for its activation when Ca2+ recedes. At high resting ER-Ca2+ concentration, the ER-luminal STIM1 domain is kept monomeric but undergoes di/multimerization once stores are depleted. Luminal STIM1 multimerization is essential to unleash the STIM C-terminal binding site for Orai1 channels. However, structural basis of the luminal association sites has so far been elusive. Here, we employed molecular dynamics (MD) simulations and identified two essential di/multimerization segments, the α7 and the adjacent region near the α9-helix in the sterile alpha motif (SAM) domain. Based on MD results, we targeted the two STIM1 SAM domains by engineering point mutations. These mutations interfered with higher-order multimerization of ER-luminal fragments in biochemical assays and puncta formation in live-cell experiments upon Ca2+ store depletion. The STIM1 multimerization impeded mutants significantly reduced Ca2+ entry via Orai1, decreasing the Ca2+ oscillation frequency as well as store-operated Ca2+ entry. Combination of the ER-luminal STIM1 multimerization mutations with gain of function mutations and coexpression of Orai1 partially ameliorated functional defects. Our data point to a hydrophobicity-driven binding within the ER-luminal STIM1 multimer that needs to switch between resting monomeric and activated multimeric state. Altogether, these data reveal that interactions between SAM domains of STIM1 monomers are critical for multimerization and activation of the protein.
Collapse
Affiliation(s)
- Matthias Sallinger
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Christina Humer
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Hwei Ling Ong
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Sasirekha Narayanasamy
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Qi Tong Lin
- Department of Physiology and Pharmacology, Western University, London, ONN6A5C1, Canada
| | - Marc Fahrner
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Herwig Grabmayr
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Sascha Berlansky
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Sean Choi
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Tony Schmidt
- Department of Medical Physics and Biophysics, Medical University of Graz, Graz8010, Austria
| | - Lena Maltan
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Lara Atzgerstorfer
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Martin Niederwieser
- Department of Medical Physics and Biophysics, Medical University of Graz, Graz8010, Austria
| | - Irene Frischauf
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, Western University, London, ONN6A5C1, Canada
| | - Indu Ambudkar
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892
| | - Romana Leitner
- Institute of Biophysics, Johannes Kepler University Linz, Linz4040, Austria
| | - Daniel Bonhenry
- Department of Physics and Materials Science, Faculty of Science, Technology and Medicine, University of Luxembourg, Esch-sur-AlzetteL1511, Luxembourg
| | - Rainer Schindl
- Department of Medical Physics and Biophysics, Medical University of Graz, Graz8010, Austria
| |
Collapse
|
3
|
Wang L, Noyer L, Wang YH, Tao AY, Li W, Zhu J, Saavedra P, Hoda ST, Yang J, Feske S. ORAI3 is dispensable for store-operated Ca2+ entry and immune responses by lymphocytes and macrophages. J Gen Physiol 2022; 154:213360. [PMID: 35861698 PMCID: PMC9532584 DOI: 10.1085/jgp.202213104] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 06/24/2022] [Indexed: 01/23/2023] Open
Abstract
Ca2+ signals regulate the function of many immune cells and promote immune responses to infection, cancer, and autoantigens. Ca2+ influx in immune cells is mediated by store-operated Ca2+ entry (SOCE) that results from the opening of Ca2+ release-activated Ca2+ (CRAC) channels. The CRAC channel is formed by three plasma membrane proteins, ORAI1, ORAI2, and ORAI3. Of these, ORAI1 is the best studied and plays important roles in immune function. By contrast, the physiological role of ORAI3 in immune cells remains elusive. We show here that ORAI3 is expressed in many immune cells including macrophages, B cells, and T cells. To investigate ORAI3 function in immune cells, we generated Orai3-/- mice. The development of lymphoid and myeloid cells in the thymus and bone marrow was normal in Orai3-/- mice, as was the composition of immune cells in secondary lymphoid organs. Deletion of Orai3 did not affect SOCE in B cells and T cells but moderately enhanced SOCE in macrophages. Orai3-deficient macrophages, B cells, and T cells had normal effector functions in vitro. Immune responses in vivo, including humoral immunity (T cell dependent or independent) and antitumor immunity, were normal in Orai3-/- mice. Moreover, Orai3-/- mice showed no differences in susceptibility to septic shock, experimental autoimmune encephalomyelitis, or collagen-induced arthritis. We conclude that despite its expression in myeloid and lymphoid cells, ORAI3 appears to be dispensable or redundant for physiological and pathological immune responses mediated by these cells.
Collapse
Affiliation(s)
- Liwei Wang
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Lucile Noyer
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Yin-Hu Wang
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Anthony Y. Tao
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Wenyi Li
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Jingjie Zhu
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Pedro Saavedra
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Syed T. Hoda
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Jun Yang
- Department of Pathology, New York University Grossman School of Medicine, New York, NY
| | - Stefan Feske
- Department of Pathology, New York University Grossman School of Medicine, New York, NY,Correspondence to Stefan Feske:
| |
Collapse
|
4
|
Kashir J, Ganesh D, Jones C, Coward K. OUP accepted manuscript. Hum Reprod Open 2022; 2022:hoac003. [PMID: 35261925 PMCID: PMC8894871 DOI: 10.1093/hropen/hoac003] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/16/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Oocyte activation deficiency (OAD) is attributed to the majority of cases underlying failure of ICSI cycles, the standard treatment for male factor infertility. Oocyte activation encompasses a series of concerted events, triggered by sperm-specific phospholipase C zeta (PLCζ), which elicits increases in free cytoplasmic calcium (Ca2+) in spatially and temporally specific oscillations. Defects in this specific pattern of Ca2+ release are directly attributable to most cases of OAD. Ca2+ release can be clinically mediated via assisted oocyte activation (AOA), a combination of mechanical, electrical and/or chemical stimuli which artificially promote an increase in the levels of intra-cytoplasmic Ca2+. However, concerns regarding safety and efficacy underlie potential risks that must be addressed before such methods can be safely widely used. OBJECTIVE AND RATIONALE Recent advances in current AOA techniques warrant a review of the safety and efficacy of these practices, to determine the extent to which AOA may be implemented in the clinic. Importantly, the primary challenges to obtaining data on the safety and efficacy of AOA must be determined. Such questions require urgent attention before widespread clinical utilization of such protocols can be advocated. SEARCH METHODS A literature review was performed using databases including PubMed, Web of Science, Medline, etc. using AOA, OAD, calcium ionophores, ICSI, PLCζ, oocyte activation, failed fertilization and fertilization failure as keywords. Relevant articles published until June 2019 were analysed and included in the review, with an emphasis on studies assessing large-scale efficacy and safety. OUTCOMES Contradictory studies on the safety and efficacy of AOA do not yet allow for the establishment of AOA as standard practice in the clinic. Heterogeneity in study methodology, inconsistent sample inclusion criteria, non-standardized outcome assessments, restricted sample size and animal model limitations render AOA strictly experimental. The main scientific concern impeding AOA utilization in the clinic is the non-physiological method of Ca2+ release mediated by most AOA agents, coupled with a lack of holistic understanding regarding the physiological mechanism(s) underlying Ca2+ release at oocyte activation. LIMITATIONS, REASONS FOR CAUTION The number of studies with clinical relevance using AOA remains significantly low. A much wider range of studies examining outcomes using multiple AOA agents are required. WIDER IMPLICATIONS In addition to addressing the five main challenges of studies assessing AOA safety and efficacy, more standardized, large-scale, multi-centre studies of AOA, as well as long-term follow-up studies of children born from AOA, would provide evidence for establishing AOA as a treatment for infertility. The delivery of an activating agent that can more accurately recapitulate physiological fertilization, such as recombinant PLCζ, is a promising prospect for the future of AOA. Further to PLCζ, many other avenues of physiological oocyte activation also require urgent investigation to assess other potential physiological avenues of AOA. STUDY FUNDING/COMPETING INTERESTS D.G. was supported by Stanford University’s Bing Overseas Study Program. J.K. was supported by a Healthcare Research Fellowship Award (HF-14-16) made by Health and Care Research Wales (HCRW), alongside a National Science, Technology, and Innovation plan (NSTIP) project grant (15-MED4186-20) awarded by the King Abdulaziz City for Science and Technology (KACST). The authors have no competing interests to declare.
Collapse
Affiliation(s)
| | | | - Celine Jones
- Nuffield Department of Women’s & Reproductive Health, University of Oxford, Level 3, Women’s Centre, John Radcliffe Hospital, Oxford, UK
| | - Kevin Coward
- Correspondence address. Nuffield Department of Women’s & Reproductive Health, University of Oxford, Level 3, Women’s Centre, John Radcliffe Hospital, Oxford, OS3 9DU, UK. E-mail: https://orcid.org/0000-0003-3577-4041
| |
Collapse
|
5
|
Novello MJ, Zhu J, Zhang M, Feng Q, Stathopulos PB. Synergistic stabilization by nitrosoglutathione-induced thiol modifications in the stromal interaction molecule-2 luminal domain suppresses basal and store operated calcium entry. Sci Rep 2020; 10:10177. [PMID: 32576932 PMCID: PMC7311479 DOI: 10.1038/s41598-020-66961-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 06/01/2020] [Indexed: 11/25/2022] Open
Abstract
Stromal interaction molecule−1 and −2 (STIM1/2) are endoplasmic reticulum (ER) membrane-inserted calcium (Ca2+) sensing proteins that, together with Orai1-composed Ca2+ channels on the plasma membrane (PM), regulate intracellular Ca2+ levels. Recent evidence suggests that S-nitrosylation of the luminal STIM1 Cys residues inhibits store operated Ca2+ entry (SOCE). However, the effects of thiol modifications on STIM2 during nitrosative stress and their role in regulating basal Ca2+ levels remain unknown. Here, we demonstrate that the nitric oxide (NO) donor nitrosoglutathione (GSNO) thermodynamically stabilizes the STIM2 Ca2+ sensing region in a Cys-specific manner. We uncovered a remarkable synergism in this stabilization involving the three luminal Cys of STIM2, which is unique to this paralog. S-Nitrosylation causes structural perturbations that converge on the face of the EF-hand and sterile α motif (EF-SAM) domain, implicated in unfolding-coupled activation. In HEK293T cells, enhanced free basal cytosolic Ca2+ and SOCE mediated by STIM2 overexpression could be attenuated by GSNO or mutation of the modifiable Cys located in the luminal domain. Collectively, we identify the Cys residues within the N-terminal region of STIM2 as modifiable targets during nitrosative stress that can profoundly and cooperatively affect basal Ca2+ and SOCE regulation.
Collapse
Affiliation(s)
- Matthew J Novello
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - Jinhui Zhu
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada.,Dentistry, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - MengQi Zhang
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada.,Faculty of Medicine, University of Ottawa, Ottawa, Ontario, K1H8M5, Canada
| | - Qingping Feng
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada.
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada.
| |
Collapse
|
6
|
Noble M, Lin QT, Sirko C, Houpt JA, Novello MJ, Stathopulos PB. Structural Mechanisms of Store-Operated and Mitochondrial Calcium Regulation: Initiation Points for Drug Discovery. Int J Mol Sci 2020; 21:E3642. [PMID: 32455637 PMCID: PMC7279490 DOI: 10.3390/ijms21103642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/11/2020] [Accepted: 05/17/2020] [Indexed: 12/18/2022] Open
Abstract
Calcium (Ca2+) is a universal signaling ion that is essential for the life and death processes of all eukaryotes. In humans, numerous cell stimulation pathways lead to the mobilization of sarco/endoplasmic reticulum (S/ER) stored Ca2+, resulting in the propagation of Ca2+ signals through the activation of processes, such as store-operated Ca2+ entry (SOCE). SOCE provides a sustained Ca2+ entry into the cytosol; moreover, the uptake of SOCE-mediated Ca2+ by mitochondria can shape cytosolic Ca2+ signals, function as a feedback signal for the SOCE molecular machinery, and drive numerous mitochondrial processes, including adenosine triphosphate (ATP) production and distinct cell death pathways. In recent years, tremendous progress has been made in identifying the proteins mediating these signaling pathways and elucidating molecular structures, invaluable for understanding the underlying mechanisms of function. Nevertheless, there remains a disconnect between using this accumulating protein structural knowledge and the design of new research tools and therapies. In this review, we provide an overview of the Ca2+ signaling pathways that are involved in mediating S/ER stored Ca2+ release, SOCE, and mitochondrial Ca2+ uptake, as well as pinpoint multiple levels of crosstalk between these pathways. Further, we highlight the significant protein structures elucidated in recent years controlling these Ca2+ signaling pathways. Finally, we describe a simple strategy that aimed at applying the protein structural data to initiating drug design.
Collapse
Affiliation(s)
- Megan Noble
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Qi-Tong Lin
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Christian Sirko
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Jacob A. Houpt
- Department of Medicine, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada;
| | - Matthew J. Novello
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| |
Collapse
|
7
|
Wasilewska I, Gupta RK, Wojtaś B, Palchevska O, Kuźnicki J. stim2b Knockout Induces Hyperactivity and Susceptibility to Seizures in Zebrafish Larvae. Cells 2020; 9:cells9051285. [PMID: 32455839 PMCID: PMC7291033 DOI: 10.3390/cells9051285] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 12/13/2022] Open
Abstract
In neurons, stromal interaction molecule (STIM) proteins regulate store-operated Ca2+ entry (SOCE) and are involved in calcium signaling pathways. However, STIM activity in neurological diseases is unclear and should be clarified by studies that are performed in vivo rather than in cultured cells in vitro. The present study investigated the role of neuronal Stim2b protein in zebrafish. We generated stim2b knockout zebrafish, which were fertile and had a regular lifespan. Using various behavioral tests, we found that stim2b−/− zebrafish larvae were hyperactive compared with wild-type fish. The mutants exhibited increases in mobility and thigmotaxis and disruptions of phototaxis. They were also more sensitive to pentylenetetrazol and glutamate treatments. Using lightsheet microscopy, a higher average oscillation frequency and higher average amplitude of neuronal Ca2+ oscillations were observed in stim2b−/− larvae. RNA sequencing detected upregulation of the annexin 3a and gpr39 genes and downregulation of the rrm2, neuroguidin, and homer2 genes. The latter gene encodes a protein that is involved in several processes that are involved in Ca2+ homeostasis in neurons, including metabotropic glutamate receptors. We propose that Stim2b deficiency in neurons dysregulates SOCE and triggers changes in gene expression, thereby causing abnormal behavior, such as hyperactivity and susceptibility to seizures.
Collapse
Affiliation(s)
- Iga Wasilewska
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland; (I.W.); (R.K.G.); (O.P.)
| | - Rishikesh Kumar Gupta
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland; (I.W.); (R.K.G.); (O.P.)
| | - Bartosz Wojtaś
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland;
| | - Oksana Palchevska
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland; (I.W.); (R.K.G.); (O.P.)
| | - Jacek Kuźnicki
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland; (I.W.); (R.K.G.); (O.P.)
- Correspondence:
| |
Collapse
|
8
|
Coordination of a Single Calcium Ion in the EF-hand Maintains the Off State of the Stromal Interaction Molecule Luminal Domain. J Mol Biol 2020; 432:367-383. [DOI: 10.1016/j.jmb.2019.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 09/17/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022]
|
9
|
Butorac C, Krizova A, Derler I. Review: Structure and Activation Mechanisms of CRAC Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:547-604. [PMID: 31646526 DOI: 10.1007/978-3-030-12457-1_23] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Ca2+ release activated Ca2+ (CRAC) channels represent a primary pathway for Ca2+ to enter non-excitable cells. The two key players in this process are the stromal interaction molecule (STIM), a Ca2+ sensor embedded in the membrane of the endoplasmic reticulum, and Orai, a highly Ca2+ selective ion channel located in the plasma membrane. Upon depletion of the internal Ca2+ stores, STIM is activated, oligomerizes, couples to and activates Orai. This review provides an overview of novel findings about the CRAC channel activation mechanisms, structure and gating. In addition, it highlights, among diverse STIM and Orai mutants, also the disease-related mutants and their implications.
Collapse
Affiliation(s)
- Carmen Butorac
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria
| | - Adéla Krizova
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria.
| |
Collapse
|
10
|
The 2β Splice Variation Alters the Structure and Function of the Stromal Interaction Molecule Coiled-Coil Domains. Int J Mol Sci 2018; 19:ijms19113316. [PMID: 30366379 PMCID: PMC6274866 DOI: 10.3390/ijms19113316] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 10/21/2018] [Accepted: 10/22/2018] [Indexed: 12/16/2022] Open
Abstract
Stromal interaction molecule (STIM)-1 and -2 regulate agonist-induced and basal cytosolic calcium (Ca2+) levels after oligomerization and translocation to endoplasmic reticulum (ER)-plasma membrane (PM) junctions. At these junctions, the STIM cytosolic coiled-coil (CC) domains couple to PM Orai1 proteins and gate these Ca2+ release-activated Ca2+ (CRAC) channels, which facilitate store-operated Ca2+ entry (SOCE). Unlike STIM1 and STIM2, which are SOCE activators, the STIM2β splice variant contains an 8-residue insert located within the conserved CCs which inhibits SOCE. It remains unclear if the 2β insert further depotentiates weak STIM2 coupling to Orai1 or independently causes structural perturbations which prevent SOCE. Here, we use far-UV circular dichroism, light scattering, exposed hydrophobicity analysis, solution small angle X-ray scattering, and a chimeric STIM1/STIM2β functional assessment to provide insights into the molecular mechanism by which the 2β insert precludes SOCE activation. We find that the 2β insert reduces the overall α-helicity and enhances the exposed hydrophobicity of the STIM2 CC domains in the absence of a global conformational change. Remarkably, incorporation of the 2β insert into the STIM1 context not only affects the secondary structure and hydrophobicity as observed for STIM2, but also eliminates the more robust SOCE response mediated by STIM1. Collectively, our data show that the 2β insert directly precludes Orai1 channel activation by inducing structural perturbations in the STIM CC region.
Collapse
|
11
|
Novello MJ, Zhu J, Feng Q, Ikura M, Stathopulos PB. Structural elements of stromal interaction molecule function. Cell Calcium 2018; 73:88-94. [PMID: 29698850 DOI: 10.1016/j.ceca.2018.04.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 04/13/2018] [Indexed: 02/02/2023]
Abstract
Stromal interaction molecule (STIM)-1 and -2 are multi-domain, single-pass transmembrane proteins involved in sensing changes in compartmentalized calcium (Ca2+) levels and transducing this cellular signal to Orai1 channel proteins. Our understanding of the molecular mechanisms underlying STIM signaling has been dramatically improved through available X-ray crystal and solution NMR structures. This high-resolution structural data has revealed that intricate intramolecular and intermolecular protein-protein interactions are involved in converting STIMs from the quiescent to activation-competent states. This review article summarizes the current high resolution structural data on specific EF-hand, sterile α motif and coiled-coil interactions which drive STIM function in the activation of Orai1 channels. Further, the work discusses the effects of post-translational modifications on the structure and function of STIMs. Future structural studies on larger STIM:Orai complexes will be critical to fully defining the molecular bases for STIM function and how post-translational modifications influence these mechanisms.
Collapse
Affiliation(s)
- Matthew J Novello
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Jinhui Zhu
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Qingping Feng
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Mitsuhiko Ikura
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada.
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
| |
Collapse
|
12
|
Berna-Erro A, Jardin I, Salido GM, Rosado JA. Role of STIM2 in cell function and physiopathology. J Physiol 2017; 595:3111-3128. [PMID: 28087881 DOI: 10.1113/jp273889] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 01/03/2017] [Indexed: 01/01/2023] Open
Abstract
An endoplasmic reticulum (ER)-resident protein that regulates cytosolic and ER free-Ca2+ concentration by induction of store-operated calcium entry: that is the original definition of STIM2 and its function. While its activity strongly depends on the amount of calcium stored in the ER, its function goes further, to intracellular signalling and gene expression. Initially under-studied owing to the prominent function of STIM1, STIM2 came to be regarded as vital in mice, gradually emerging as an important player in the nervous system, and cooperating with STIM1 in the immune system. STIM2 has also been proposed as a relevant player in pathological conditions related to ageing, Alzheimer's and Huntington's diseases, autoimmune disorders and cancer. The discovery of additional functions, together with new splicing forms with opposite roles, has clarified existing controversies about STIM2 function in SOCE. With STIM2 being essential for life, but apparently not for development, newly available data demonstrate a complex and still intriguing behaviour that this review summarizes, updating current knowledge of STIM2 function.
Collapse
Affiliation(s)
- Alejandro Berna-Erro
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003, Barcelona, Spain
| | - Isaac Jardin
- Department of Physiology (Cell Physiology Research Group), University of Extremadura, 10003, Cáceres, Spain
| | - Gines M Salido
- Department of Physiology (Cell Physiology Research Group), University of Extremadura, 10003, Cáceres, Spain
| | - Juan A Rosado
- Department of Physiology (Cell Physiology Research Group), University of Extremadura, 10003, Cáceres, Spain
| |
Collapse
|
13
|
Structural perturbations induced by Asn131 and Asn171 glycosylation converge within the EFSAM core and enhance stromal interaction molecule-1 mediated store operated calcium entry. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:1054-1063. [PMID: 27865927 DOI: 10.1016/j.bbamcr.2016.11.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/11/2016] [Accepted: 11/14/2016] [Indexed: 11/21/2022]
Abstract
A major intracellular calcium (Ca2+) uptake pathway in both excitable and non-excitable eukaryotic cells is store-operated Ca2+ entry (SOCE). SOCE is the process by which endoplasmic reticulum (ER)-stored Ca2+ depletion leads to activation of plasma membrane Ca2+ channels to provide a sustained increase in cytosolic Ca2+ levels that mediate a plethora of physiological processes ranging from the immune response to platelet aggregation. Stromal interaction molecule-1 (STIM1) is the principal regulator of SOCE and responds to changes in ER stored Ca2+ through luminal sensing machinery composed of EF-hand and SAM domains (EFSAM). The EFSAM domain can undergo N-glycosylation at Asn131 and Asn171 sites; however, the precise role of EFSAM N-glycosylation in the Ca2+ sensing mechanism of STIM1 is unclear. By establishing a site-specific chemical approach to covalently linking glucose to EFSAM and examining α-helicity, thermal stability, three dimensional atomic-resolution structure, Ca2+ binding affinity and oligomerization, we show that N-glycosylation of the EFSAM domain enhances the properties that promote STIM1 activation. This augmentation occurs through changes in structure localized near the Asn131 and Asn171 sites that together permeate through the protein core and lead to decreased Ca2+ binding affinity, reduced stability and enhanced oligomerization. Congruently, Ca2+ influx via SOCE in HEK293 cells co-expressing Orai1 and STIM1 was diminished when N-glycosylation was blocked by introducing Asn131Gln and Asn171Gln mutations. Collectively, our data suggests that N-glycosylation enhances the EFSAM destabilization-coupled oligomerization in response to ER Ca2+ depletion thereby augmenting the role of STIM1 as a robust ON/OFF regulator of SOCE. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
Collapse
|
14
|
Abstract
Ca(2+)entry into the cell via store-operated Ca(2+)release-activated Ca(2+)(CRAC) channels triggers diverse signaling cascades that affect cellular processes like cell growth, gene regulation, secretion, and cell death. These store-operated Ca(2+)channels open after depletion of intracellular Ca(2+)stores, and their main features are fully reconstituted by the two molecular key players: the stromal interaction molecule (STIM) and Orai. STIM represents an endoplasmic reticulum-located Ca(2+)sensor, while Orai forms a highly Ca(2+)-selective ion channel in the plasma membrane. Functional as well as mutagenesis studies together with structural insights about STIM and Orai proteins provide a molecular picture of the interplay of these two key players in the CRAC signaling cascade. This review focuses on the main experimental advances in the understanding of the STIM1-Orai choreography, thereby establishing a portrait of key mechanistic steps in the CRAC channel signaling cascade. The focus is on the activation of the STIM proteins, the subsequent coupling of STIM1 to Orai1, and the consequent structural rearrangements that gate the Orai channels into the open state to allow Ca(2+)permeation into the cell.
Collapse
Affiliation(s)
- Isabella Derler
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria; and
| | - Isaac Jardin
- Department of Physiology, University of Extremadura, Cáceres, Spain
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria; and
| |
Collapse
|
15
|
Abstract
Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.
Collapse
Affiliation(s)
- Murali Prakriya
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
| | - Richard S Lewis
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
| |
Collapse
|
16
|
Light generation of intracellular Ca(2+) signals by a genetically encoded protein BACCS. Nat Commun 2015; 6:8021. [PMID: 26282514 PMCID: PMC4557345 DOI: 10.1038/ncomms9021] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/09/2015] [Indexed: 12/13/2022] Open
Abstract
Ca2+ signals are highly regulated in a spatiotemporal manner in numerous cellular physiological events. Here we report a genetically engineered blue light-activated Ca2+ channel switch (BACCS), as an optogenetic tool for generating Ca2+ signals. BACCS opens Ca2+-selective ORAI ion channels in response to light. A BACCS variant, dmBACCS2, combined with Drosophila Orai, elevates the Ca2+ concentration more rapidly, such that Ca2+ elevation in mammalian cells is observed within 1 s on light exposure. Using BACCSs, we successfully control cellular events including NFAT-mediated gene expression. In the mouse olfactory system, BACCS mediates light-dependent electrophysiological responses. Furthermore, we generate BACCS mutants, which exhibit fast and slow recovery of intracellular Ca2+. Thus, BACCSs are a useful optogenetic tool for generating temporally various intracellular Ca2+ signals with a large dynamic range, and will be applicable to both in vitro and in vivo studies. Current tools for optogenetic control of intracellular calcium signals currently suffer from slow response time or low dynamic range. Here the authors develop blue light-activated Ca2+ channel switch (BACCS) that modulates the activity of Ca2+-sensitive Orai channels with high temporal resolution and large dynamic range.
Collapse
|
17
|
Cai X, Wang X, Patel S, Clapham DE. Insights into the early evolution of animal calcium signaling machinery: a unicellular point of view. Cell Calcium 2014; 57:166-73. [PMID: 25498309 PMCID: PMC4355082 DOI: 10.1016/j.ceca.2014.11.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 11/18/2014] [Accepted: 11/24/2014] [Indexed: 11/15/2022]
Abstract
The basic principles of Ca(2+) regulation emerged early in prokaryotes. Ca(2+) signaling acquired more extensive and varied functions when life evolved into multicellular eukaryotes with intracellular organelles. Animals, fungi and plants display differences in the mechanisms that control cytosolic Ca(2+) concentrations. The aim of this review is to examine recent findings from comparative genomics of Ca(2+) signaling molecules in close unicellular relatives of animals and in common unicellular ancestors of animals and fungi. Also discussed are the evolution and origins of the sperm-specific CatSper channel complex, cation/Ca(2+) exchangers and four-domain voltage-gated Ca(2+) channels. Newly identified evolutionary evidence suggests that the distinct Ca(2+) signaling machineries in animals, plants and fungi likely originated from an ancient Ca(2+) signaling machinery prior to early eukaryotic radiation.
Collapse
Affiliation(s)
- Xinjiang Cai
- Division of Endocrinology, Metabolism and Nutrition, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA.
| | - Xiangbing Wang
- Division of Endocrinology, Metabolism and Nutrition, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - David E Clapham
- Howard Hughes Medical Institute, Department of Cardiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| |
Collapse
|
18
|
Stathopulos PB, Ikura M. Structural aspects of calcium-release activated calcium channel function. Channels (Austin) 2013; 7:344-53. [PMID: 24213636 DOI: 10.4161/chan.26734] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Store-operated calcium (Ca(2+)) entry is the process by which molecules located on the endo/sarcoplasmic reticulum (ER/SR) respond to decreased luminal Ca(2+) levels by signaling Ca(2+) release activated Ca(2+) channels (CRAC) channels to open on the plasma membrane (PM). This activation of PM CRAC channels provides a sustained cytosolic Ca(2+) elevation associated with myriad physiological processes. The identities of the molecules which mediate SOCE include stromal interaction molecules (STIMs), functioning as the ER/SR luminal Ca(2+) sensors, and Orai proteins, forming the PM CRAC channels. This review examines the current available high-resolution structural information on these CRAC molecular components with particular focus on the solution structures of the luminal STIM Ca(2+) sensing domains, the crystal structures of cytosolic STIM fragments, a closed Orai hexameric crystal structure and a structure of an Orai1 N-terminal fragment in complex with calmodulin. The accessible structural data are discussed in terms of potential mechanisms of action and cohesiveness with functional observations.
Collapse
Affiliation(s)
- Peter B Stathopulos
- Princess Margaret Cancer Centre; Department of Medical Biophysics; University of Toronto; Toronto, ON, Canada
| | - Mitsuhiko Ikura
- Princess Margaret Cancer Centre; Department of Medical Biophysics; University of Toronto; Toronto, ON, Canada
| |
Collapse
|
19
|
Oligomerization and Ca2+/calmodulin control binding of the ER Ca2+-sensors STIM1 and STIM2 to plasma membrane lipids. Biosci Rep 2013; 33:BSR20130089. [PMID: 24044355 PMCID: PMC3814058 DOI: 10.1042/bsr20130089] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Ca2+ (calcium) homoeostasis and signalling rely on physical contacts between Ca2+ sensors in the ER (endoplasmic reticulum) and Ca2+ channels in the PM (plasma membrane). STIM1 (stromal interaction molecule 1) and STIM2 Ca2+ sensors oligomerize upon Ca2+ depletion in the ER lumen, contact phosphoinositides at the PM via their cytosolic lysine (K)-rich domains, and activate Ca2+ channels. Differential sensitivities of STIM1 and STIM2 towards ER luminal Ca2+ have been studied but responses towards elevated cytosolic Ca2+ concentration and the mechanism of lipid binding remain unclear. We found that tetramerization of the STIM1 K-rich domain is necessary for efficient binding to PI(4,5)P2-containing PM-like liposomes consistent with an oligomerization-driven STIM1 activation. In contrast, dimerization of STIM2 K-rich domain was sufficient for lipid binding. Furthermore, the K-rich domain of STIM2, but not of STIM1, forms an amphipathic α-helix. These distinct features of the STIM2 K-rich domain cause an increased affinity for PI(4,5)P2, consistent with the lower activation threshold of STIM2 and a function as regulator of basal Ca2+ levels. Concomitant with higher affinity for PM lipids, binding of CaM (calmodulin) inhibited the interaction of the STIM2 K-rich domain with liposomes in a Ca2+ and PI(4,5)P2 concentration-dependent manner. Therefore we suggest that elevated cytosolic Ca2+ concentration down-regulates STIM2-mediated ER–PM contacts via CaM binding.
Collapse
|
20
|
Abstract
Store-operated calcium (Ca(2+)) entry (SOCE) is a vital Ca(2+) signaling pathway in nonexcitable as well as electrically excitable cells, regulating countless physiological and pathophysiological pathways. Stromal interaction molecules (STIMs) are the principal regulating molecules of SOCE, sensing changes in sarco-/endoplasmic reticulum (S/ER) luminal Ca(2+) levels and directly interacting with the Orai channel subunits to orchestrate the opening of Ca(2+) release-activated Ca(2+) (CRAC) channels. Recent atomic resolution structures on human STIM1 and STIM2 have illuminated critical mechanisms of STIM function in SOCE; further, the first high-resolution structure of the Drosophila melanogaster Orai channel has revealed vital data on the atomic composition of the CRAC channel pore and the assembly of individual Orai subunits. This chapter focuses on the mechanistic information garnered from these high-resolution structures and the supporting biophysical, biochemical, and live cell work that has enhanced our understanding of the relationship between STIM and Orai structural features and CRAC channel function.
Collapse
|
21
|
Miao YL, Williams CJ. Calcium signaling in mammalian egg activation and embryo development: the influence of subcellular localization. Mol Reprod Dev 2012; 79:742-56. [PMID: 22888043 DOI: 10.1002/mrd.22078] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Accepted: 07/27/2012] [Indexed: 11/07/2022]
Abstract
Calcium (Ca(2+) ) signals drive the fundamental events surrounding fertilization and the activation of development in all species examined to date. Initial studies of Ca(2+) signaling at fertilization in marine animals were tightly linked to new discoveries of bioluminescent proteins and their use as fluorescent Ca(2+) sensors. Since that time, there has been rapid progress in our understanding of the key functions for Ca(2+) in many cell types and of the impact of cellular localization on Ca(2+) signaling pathways. In this review, which focuses on mammalian egg activation, we consider how Ca(2+) is regulated and stored at different stages of oocyte development and examine the functions of molecules that serve as both regulators of Ca(2+) release and effectors of Ca(2+) signals. We then summarize studies exploring how Ca(2+) directs downstream effectors mediating both egg activation and later signaling events required for successful preimplantation embryo development. Throughout this review, we focus attention on how localization of Ca(2+) signals influences downstream signaling events, and attempt to highlight gaps in our knowledge that are ripe for future research.
Collapse
Affiliation(s)
- Yi-Liang Miao
- Reproductive Medicine Group, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
| | | |
Collapse
|
22
|
Ercan E, Chung SH, Bhardwaj R, Seedorf M. Di-Arginine Signals and the K-Rich Domain Retain the Ca2+Sensor STIM1 in the Endoplasmic Reticulum. Traffic 2012; 13:992-1003. [DOI: 10.1111/j.1600-0854.2012.01359.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 03/28/2012] [Accepted: 04/12/2012] [Indexed: 11/30/2022]
Affiliation(s)
| | - Shan-Hua Chung
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH); DKFZ-ZMBH Alliance; Im Neuenheimer Feld 282; 69120; Heidelberg; Germany
| | - Rajesh Bhardwaj
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH); DKFZ-ZMBH Alliance; Im Neuenheimer Feld 282; 69120; Heidelberg; Germany
| | - Matthias Seedorf
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH); DKFZ-ZMBH Alliance; Im Neuenheimer Feld 282; 69120; Heidelberg; Germany
| |
Collapse
|
23
|
Olivera JF, Pizarro G. A study of store dependent Ca2+ influx in frog skeletal muscle. J Muscle Res Cell Motil 2012; 33:131-43. [DOI: 10.1007/s10974-012-9293-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 04/06/2012] [Indexed: 01/17/2023]
|
24
|
López E, Salido GM, Rosado JA, Berna-Erro A. Unraveling STIM2 function. J Physiol Biochem 2012; 68:619-33. [PMID: 22477146 DOI: 10.1007/s13105-012-0163-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 03/13/2012] [Indexed: 12/11/2022]
Abstract
The discovery of molecular players in capacitative calcium (Ca(2+)) entry, also referred to as store-operated Ca(2+) entry (SOCE), supposed a great advance in the knowledge of cellular mechanisms of Ca(2+) entry, which are essential for a broad range of cellular functions. The identification of STIM1 and STIM2 proteins as the sensors of Ca(2+) stored in the endoplasmic reticulum unraveled the mechanism by which depletion of intracellular Ca(2+) stores is communicated to store-operated Ca(2+) channels located in the plasma membrane, triggering the activation of SOCE and intracellular Ca(2+)-dependent signaling cascades. Initial studies suggested a dominant function of STIM1 in SOCE and SOCE-dependent cellular functions compared to STIM2, especially those that participate in immune responses. Consequently, most of the subsequent studies focused on STIM1. However, during the last years, STIM2 has been demonstrated to play a more relevant and complex function than initially reported, being even important to sustain normal life in mice. These studies have led to reconsider the role of STIM2 in SOCE and its relevance in cellular physiology. This review is intended to summarize and provide an overview of the current data available about this exciting isoform, STIM2, and its actual position together with STIM1 in the mechanism of SOCE.
Collapse
Affiliation(s)
- Esther López
- Department of Physiology (Cellular Physiology Research Group), University of Extremadura, Av. Universidad s/n, 10003, Cáceres, Spain
| | | | | | | |
Collapse
|
25
|
|
26
|
Collins SR, Meyer T. Evolutionary origins of STIM1 and STIM2 within ancient Ca2+ signaling systems. Trends Cell Biol 2011; 21:202-11. [PMID: 21288721 PMCID: PMC3175768 DOI: 10.1016/j.tcb.2011.01.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 12/17/2010] [Accepted: 01/04/2011] [Indexed: 11/26/2022]
Abstract
Human stromal interaction molecule (STIM) proteins are parts of elaborate eukaryotic Ca(2+) signaling systems that include numerous plasma membrane (PM), endoplasmic reticulum (ER), and mitochondrial Ca(2+) transporters, channels and regulators. STIM2 and STIM1 function as Ca(2+) sensors with different sensitivities for ER Ca(2+). They translocate to ER-PM junctions and open PM Orai Ca(2+) influx channels when receptor-mediated Ca(2+) release lowers ER Ca(2+) levels. The resulting increase in cytosolic Ca(2+) leads to the activation of numerous Ca(2+) effector proteins that in turn regulate differentiation, cell contraction, secretion and other cell functions. In this review, we use an evolutionary perspective to survey molecular activation mechanisms in the Ca(2+) signaling system, with a particular focus on regulatory motifs and functions of the two STIM proteins. We discuss the presence and absence of STIM genes in different species, the order of appearance of STIM versus Orai, and the evolutionary addition of new signaling domains to STIM proteins.
Collapse
Affiliation(s)
- Sean R Collins
- Department of Chemical and Systems Biology, Stanford University, 318 Campus Drive, Clark Building W2.1, Stanford, CA 94305-5174, USA
| | | |
Collapse
|
27
|
Stathopulos PB, Ikura M. Partial unfolding and oligomerization of stromal interaction molecules as an initiation mechanism of store operated calcium entry. Biochem Cell Biol 2010; 88:175-83. [PMID: 20453920 DOI: 10.1139/o09-125] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Spatiotemporally discrete cytoplasmic Ca2+ fluctuations are fundamental eukaryotic signals in myriad physiological and pathophysiological functions. Store-operated Ca2+ entry is the process whereby a decrease in endoplasmic reticulum (ER) luminal Ca2+ levels activates Ca2+ release activated calcium (CRAC) channels on the plasma membrane (PM), providing a sustained Ca2+ elevation to the cytoplasm and ultimately replenishing the ER lumen Ca2+ supply. Stromal interaction molecules (STIMs) are the Ca2+ sensors of the ER lumen, which macromolecularly couple depleted ER Ca2+ to the assembly and opening of PM CRAC channels. The considerable stability difference caused by Ca2+ loading and depletion within the luminal portion of STIMs modulates intramolecular cytoplasmic domain interactions essential to the assembly of PM CRAC channels. Thus, the action of the entire complex is tightly regulated through the Ca2+ sensitivity of luminal STIM domains. Recent structural and biochemical studies suggest that partial unfolding - coupled oligomerization of STIMs is a crucial step in CRAC channel activation. Based on these and other published data, this minireview discusses what is currently known about the molecular mechanism of ER Ca2+ sensing by STIMs.
Collapse
Affiliation(s)
- Peter B Stathopulos
- Division of Signaling Biology and Department of Medical Biophysics, Ontario Cancer Institute and University of Toronto, Toronto Medical Discovery Tower, MaRS Centre, 101 College St., Toronto, ON M5G 1L7, Canada
| | | |
Collapse
|
28
|
Johnstone LS, Graham SJL, Dziadek MA. STIM proteins: integrators of signalling pathways in development, differentiation and disease. J Cell Mol Med 2010; 14:1890-903. [PMID: 20561111 PMCID: PMC3823271 DOI: 10.1111/j.1582-4934.2010.01097.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The stromal interaction molecules STIM1 and STIM2 are endoplasmic reticulum Ca2+ sensors, serving to detect changes in receptor-mediated ER Ca2+ store depletion and to relay this information to plasma membrane localized proteins, including the store-operated Ca2+ channels of the ORAI family. The resulting Ca2+ influx sustains the high cytosolic Ca2+ levels required for activation of many intracellular signal transducers such as the NFAT family of transcription factors. Models of STIM protein deficiency in mice, Drosophila melanogaster and Caenorhabditis elegans, in addition to the phenotype of patients bearing mutations in STIM1 have provided great insight into the role of these proteins in cell physiology and pathology. It is now becoming clear that STIM1 and STIM2 are critical for the development and functioning of many cell types, including lymphocytes, skeletal and smooth muscle myoblasts, adipocytes and neurons, and can interact with a variety of signalling proteins and pathways in a cell- and tissue-type specific manner. This review focuses on the role of STIM proteins in development, differentiation and disease, in particular highlighting the functional differences between STIM1 and STIM2.
Collapse
Affiliation(s)
- Lorna S Johnstone
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.
| | | | | |
Collapse
|
29
|
Cai X, Patel S. Degeneration of an intracellular ion channel in the primate lineage by relaxation of selective constraints. Mol Biol Evol 2010; 27:2352-9. [PMID: 20463046 DOI: 10.1093/molbev/msq122] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Ion channel genes are highly conserved and are rarely degenerated in the primate lineage leading to humans. So far, the only well-characterized ion channel known to be degenerated in primates is the plasma membrane transient receptor potential channel TRPC2, possibly due to changes in the pheromone signaling. Here, by analyzing the sequence data from ten primate species, we have determined the degeneration process of the TPC3 gene that encodes a member of the two-pore channel (TPC) family recently implicated in Ca(2+) release by nicotinic acid adenine dinucleotide phosphate from intracellular acidic stores in animals. We show that degeneration of TPC3 likely began in the common ancestors of Apes and Old World monkeys through a conserved inactivating mutation, followed by additional deleterious mutations resulting in the generation of a TPC3 pseudogene in the descendant catarrhine lineage. Located at a chromosome recombination hot spot, catarrhine TPC3 pseudogenes underwent a series of lineage-specific rearrangements, including exon deletion and duplication. In contrast, we identify near full-length TPC3 sequences in New World monkeys and Prosimians and show that the gene is subjected to strong purifying selection and therefore likely functional. Our data provide the first evidence for relaxed functional constraints for an intracellular ion channel in primates and shed novel insights into the evolution and regulation of Ca(2+) signaling in the primate lineage.
Collapse
Affiliation(s)
- Xinjiang Cai
- Division of Cardiology, Department of Medicine, Duke University Medical Center, USA.
| | | |
Collapse
|
30
|
Stathopulos PB, Ikura M. Structurally delineating stromal interaction molecules as the endoplasmic reticulum calcium sensors and regulators of calcium release-activated calcium entry. Immunol Rev 2009; 231:113-31. [PMID: 19754893 DOI: 10.1111/j.1600-065x.2009.00814.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The endoplasmic reticulum (ER) lumen stores a crucial source of calcium (Ca2+) maintained orders of magnitude higher than the cytosol for the activation of a plethora of cellular responses transmitted in health and disease by a mutually efficient and communicative exchange of Ca2+ between compartments. A coordination of the Ca2+ signal is evident in the development of Ca2+ release-activated Ca2+ (CRAC) entry, vital to lymphocyte activation and replenishing of the ER Ca2+ stores, where modest decreases in ER luminal Ca2+ induce sustained increases in cytosolic Ca2+ sourced from steadfast extracellular Ca2+ supplies. While protein sensors that transduce Ca2+ signals in the cytosol such as calmodulin are succinctly understood, comparative data on the ER luminal Ca2+ sensors is only recently coming to light with the discovery that stromal interaction molecules (STIMs) sense variations in ER stored Ca2+ levels in the functional regulation of plasma membrane Orai proteins, the major component of CRAC channel pores. Drawing from data on the role of STIMs in the modulation of CRAC entry, this review illustrates the structural features that delimit the functional characteristics of ER Ca2+ sensors relative to well known cytoplasmic Ca2+ sensors.
Collapse
Affiliation(s)
- Peter B Stathopulos
- Division of Signaling Biology and Department of Medical Biophysics, Ontario Cancer Institute and University of Toronto, Toronto, ON, Canada
| | | |
Collapse
|
31
|
Brailoiu E, Churamani D, Cai X, Schrlau MG, Brailoiu GC, Gao X, Hooper R, Boulware MJ, Dun NJ, Marchant JS, Patel S. Essential requirement for two-pore channel 1 in NAADP-mediated calcium signaling. J Cell Biol 2009; 186:201-9. [PMID: 19620632 PMCID: PMC2717647 DOI: 10.1083/jcb.200904073] [Citation(s) in RCA: 358] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 06/25/2009] [Indexed: 12/04/2022] Open
Abstract
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a widespread and potent calcium-mobilizing messenger that is highly unusual in activating calcium channels located on acidic stores. However, the molecular identity of the target protein is unclear. In this study, we show that the previously uncharacterized human two-pore channels (TPC1 and TPC2) are endolysosomal proteins, that NAADP-mediated calcium signals are enhanced by overexpression of TPC1 and attenuated after knockdown of TPC1, and that mutation of a single highly conserved residue within a putative pore region abrogated calcium release by NAADP. Thus, TPC1 is critical for NAADP action and is likely the long sought after target channel for NAADP.
Collapse
Affiliation(s)
- Eugen Brailoiu
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140
| | - Dev Churamani
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, England, UK
| | - Xinjiang Cai
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710
| | - Michael G. Schrlau
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104
| | - G. Cristina Brailoiu
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140
| | - Xin Gao
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140
| | - Robert Hooper
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, England, UK
| | - Michael J. Boulware
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Nae J. Dun
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140
| | - Jonathan S. Marchant
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, England, UK
| |
Collapse
|
32
|
Abstract
Calcium influx through plasma membrane store-operated Ca(2+) (SOC) channels is triggered when the endoplasmic reticulum (ER) Ca(2+) store is depleted - a homeostatic Ca(2+) signalling mechanism that remained enigmatic for more than two decades. RNA-interference (RNAi) screening and molecular and cellular physiological analysis recently identified STIM1 as the mechanistic 'missing link' between the ER and the plasma membrane. STIM proteins sense the depletion of Ca(2+) from the ER, oligomerize, translocate to junctions adjacent to the plasma membrane, organize Orai or TRPC (transient receptor potential cation) channels into clusters and open these channels to bring about SOC entry.
Collapse
Affiliation(s)
- Michael D Cahalan
- Department of Physiology and Biophysics and Institute for Immunology, University of California, Irvine, CA 92697-4561, USA.
| |
Collapse
|
33
|
Stathopulos PB, Zheng L, Ikura M. Stromal interaction molecule (STIM) 1 and STIM2 calcium sensing regions exhibit distinct unfolding and oligomerization kinetics. J Biol Chem 2008; 284:728-32. [PMID: 19019825 DOI: 10.1074/jbc.c800178200] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Stromal interaction molecules (STIM) 1 and STIM2 are regulators of store-operated calcium (Ca(2+)) entry as well as basal cytoplasmic Ca(2+) levels in human cells. Despite a high sequence similarity (>65%) and analogous sequence-based domain architectures, STIM1 and STIM2 differentially influence these phenomena. Among all eukaryotes, the endoplasmic reticulum luminal portion of STIM proteins minimally encode EF-hand and sterile alpha-motif (SAM) domains (EF-SAM), which are responsible for sensing changes in Ca(2+) levels and initiating oligomerization. STIM oligomerization is a key induction step in the activation of Ca(2+)-permeable channels on the plasma membrane. Here, we show that the kinetic half-time of conversion from a monomeric to a steady oligomeric state is >70x shorter for STIM1 EF-SAM than STIM2 under similar conditions. Urea-induced rates of unfolding for STIM1 EF-SAM are >3x quicker when compared with STIM2, coherent with partial unfolding-coupled aggregation. Additionally, we demonstrate that the isoform-specific N-terminal residues beyond EF-SAM can influence the stability of this region. We postulate that distinct oligomerization dynamics of STIM isoforms have evolved to adapt to differential roles in Ca(2+) homeostasis and signaling.
Collapse
Affiliation(s)
- Peter B Stathopulos
- Division of Signaling Biology, Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | | | | |
Collapse
|
34
|
Cai X, Clapham DE. Evolutionary genomics reveals lineage-specific gene loss and rapid evolution of a sperm-specific ion channel complex: CatSpers and CatSperbeta. PLoS One 2008; 3:e3569. [PMID: 18974790 PMCID: PMC2572835 DOI: 10.1371/journal.pone.0003569] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Accepted: 10/09/2008] [Indexed: 11/18/2022] Open
Abstract
The mammalian CatSper ion channel family consists of four sperm-specific voltage-gated Ca2+ channels that are crucial for sperm hyperactivation and male fertility. All four CatSper subunits are believed to assemble into a heteromultimeric channel complex, together with an auxiliary subunit, CatSperbeta. Here, we report a comprehensive comparative genomics study and evolutionary analysis of CatSpers and CatSperbeta, with important correlation to physiological significance of molecular evolution of the CatSper channel complex. The development of the CatSper channel complex with four CatSpers and CatSperbeta originated as early as primitive metazoans such as the Cnidarian Nematostella vectensis. Comparative genomics revealed extensive lineage-specific gene loss of all four CatSpers and CatSperbeta through metazoan evolution, especially in vertebrates. The CatSper channel complex underwent rapid evolution and functional divergence, while distinct evolutionary constraints appear to have acted on different domains and specific sites of the four CatSper genes. These results reveal unique evolutionary characteristics of sperm-specific Ca2+ channels and their adaptation to sperm biology through metazoan evolution.
Collapse
Affiliation(s)
- Xinjiang Cai
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA.
| | | |
Collapse
|
35
|
Stathopulos PB, Zheng L, Li GY, Plevin MJ, Ikura M. Structural and mechanistic insights into STIM1-mediated initiation of store-operated calcium entry. Cell 2008; 135:110-22. [PMID: 18854159 DOI: 10.1016/j.cell.2008.08.006] [Citation(s) in RCA: 374] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 05/26/2008] [Accepted: 08/01/2008] [Indexed: 10/21/2022]
Abstract
Stromal interaction molecule-1 (STIM1) activates store-operated Ca2+ entry (SOCE) in response to diminished luminal Ca2+ levels. Here, we present the atomic structure of the Ca2+-sensing region of STIM1 consisting of the EF-hand and sterile alpha motif (SAM) domains (EF-SAM). The canonical EF-hand is paired with a previously unidentified EF-hand. Together, the EF-hand pair mediates mutually indispensable hydrophobic interactions between the EF-hand and SAM domains. Structurally critical mutations in the canonical EF-hand, "hidden" EF-hand, or SAM domain disrupt Ca2+ sensitivity in oligomerization via destabilization of the entire EF-SAM entity. In mammalian cells, EF-SAM destabilization mutations within full-length STIM1 induce punctae formation and activate SOCE independent of luminal Ca2+. We provide atomic resolution insight into the molecular basis for STIM1-mediated SOCE initiation and show that the folded/unfolded state of the Ca2+-sensing region of STIM is crucial to SOCE regulation.
Collapse
Affiliation(s)
- Peter B Stathopulos
- Division of Signaling Biology, Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Toronto Medical Discovery Tower, MaRS Centre, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | | | | | | | | |
Collapse
|
36
|
Gao S, Fan Y, Chen L, Lu J, Xu T, Xu P. Mechanism of different spatial distributions of Caenorhabditis elegans and human STIM1 at resting state. Cell Calcium 2008; 45:77-88. [PMID: 18667236 DOI: 10.1016/j.ceca.2008.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 06/13/2008] [Accepted: 06/16/2008] [Indexed: 11/19/2022]
Abstract
Recent studies have identified STIM1 and Orai1 as essential and conserved components of the Ca2+ release-activated Ca2+ (CRAC) channel. However, the reason STIM1 exhibits different distributions in nematode Caenorhabditis elegans and in human cells before endoplasmic reticulum (ER) calcium store depletion has not been clarified. Compared to the diffuse ER distribution of human STIM1 (H.STIM1), we found that C. elegans STIM1 (C.STIM1) was pre-oligomerized in puncta at the cell periphery before Ca2+ store depletion when expressed in HEK293 cells. Interestingly, these C.STIM1 puncta failed to induce aggregation of C. elegans Orai1 (C.Orai1), and no CRAC current was detected in quiescent cells. However, upon store depletion, C.Orai1 and C.STIM1 functioned as a pair to locally sense the store depletion signal and to activate the CRAC channel. We substituted the N-terminus of H.STIM1 for the N-terminus of C.STIM1 (H_C.STIM1), which resulted in pre-puncta resting localization. In contrast, by replacing the C-terminus of C.STIM1 with that of H.STIM1, we made a chimeric protein (C.STIM1_H) that exhibited two distribution profiles at resting state, a diffuse ER pattern like H.STIM1, and large aggregates. Taken together, our results suggest that (1) despite highly conserved functional domains, C. elegans STIM1 and human STIM1 display different spatial distributions in HEK293 cells before store depletion; (2) the C.STIM1 puncta at peripheral sites are not sufficient for the aggregation and activation of C.Orai1 in the absence of store depletion; (3) the distinct distributions of C.STIM1 and H.STIM1 at resting state are determined by the cytoplasmic region of STIM1.
Collapse
Affiliation(s)
- Shangbang Gao
- Joint Laboratory of the Institute of Biophysics & Huazhong University of Science and Technology, College of life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China
| | | | | | | | | | | |
Collapse
|
37
|
Abstract
Ca(2+) signaling pathways control many physiological processes in almost all types of animal cells such as fertilization, muscle contraction, hormone release, and learning and memory. Each animal cell type expresses a unique group of molecules from the Ca(2+) signaling 'toolkit' to control spatiotemporal patterns of Ca(2+) signaling. It is generally believed that the complex Ca(2+) signaling 'toolkit' has arisen from the ancestral multicellular organisms to fit unique physiological roles of specialized cell types. Here, we demonstrate for the first time the presence of an extensive Ca(2+) signaling 'toolkit' in the unicellular choanoflagellate Monosiga brevicollis. Choanoflagellates possess homologues of various types of animal plasma membrane Ca(2+) channels including the store-operated channel, ligand-operated channels, voltage-operated channels, second messenger-operated channels, and 5 out of 6 animal transient receptor potential channel families. Choanoflagellates also contain homologues of inositol 1,4,5-trisphosphate receptors. Furthermore, choanoflagellates master a complete set of Ca(2+) removal systems including plasma membrane and sarco/endoplasmic reticulum Ca(2+) ATPases and homologues of 3 animal cation/Ca(2+) exchanger families. Therefore, a complex Ca(2+) signaling 'toolkit' might have evolved before the emergence of multicellular animals.
Collapse
Affiliation(s)
- Xinjiang Cai
- Department of Cell Biology, Duke University Medical Center, Durham, NC, USA.
| |
Collapse
|
38
|
Zheng L, Stathopulos PB, Li GY, Ikura M. Biophysical characterization of the EF-hand and SAM domain containing Ca2+ sensory region of STIM1 and STIM2. Biochem Biophys Res Commun 2008; 369:240-6. [DOI: 10.1016/j.bbrc.2007.12.129] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Accepted: 12/11/2007] [Indexed: 01/07/2023]
|