1
|
Xu L, Liu S, Yang Y, Shu L, Sun Y. LINC00313 suppresses autophagy and promotes stemness of nasopharyngeal carcinoma cells through PTBP1/STIM1 axis. Radiother Oncol 2024; 196:110310. [PMID: 38677328 DOI: 10.1016/j.radonc.2024.110310] [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: 11/13/2023] [Revised: 04/15/2024] [Accepted: 04/19/2024] [Indexed: 04/29/2024]
Abstract
BACKGROUND Nasopharyngeal carcinoma (NPC) is a kind of malignant head and neck tumor with high mortality. lncRNAs are valuable diagnostic biomarkers and therapeutic targets for various tumors. This study investigated the effects and mechanism of LINC00313 in nasopharyngeal carcinoma. METHODS Cell Counting Kit-8 (CCK-8) and immunohistochemistry were used for assessing cell proliferation. The levels of autophagy-related proteins, and stem cell markers were detected. Immunofluorescence assay was used for LC3 detection. Methylated RNA Immunoprecipitation (meRIP) of LINC00313 in NPC cells was assessed. The localization of LINC00313 was verified by luorescence in situ hybridization (FIHS). The interaction between LINC00313 and the downstream targets were analyzed and confirmed by immunoprecipitation (RIP). Besides, the tumorigenesis roles of LINC00313 were confirmed in tumor growth mice model. RESULTS LINC00313 was increased in NPC tissues and cells. LINC00313 knockdown enhanced autophagy, and decreased stemness and cell viability of NPC cells through regulating STIM1. METTL3/IGF2BP1-mediated m6A modification promoted the stabilization and up-regulation of LINC00313. LINC00313 activated AKT/mTOR pathway in NPC cells through PTBP1/STIM1 axis. Moreover, LINC00313 promoted tumor growth and metastasis in xenograft model. CONCLUSION Upregulation of LINC00313 suppressed autophagy and promoted stemness of NPC cells through PTBP1/STIM1 axis.
Collapse
Affiliation(s)
- Lina Xu
- Department of Pathology, The Second Xiangya Hospital of Central South University, Changsha 410011, Hunan Province, PR China
| | - Sile Liu
- Department of Laboratory Medicine, Hunan Provincial People's Hospital, Changsha 410005, Hunan Province, PR China
| | - Yang Yang
- Department of Pathology, The Second Xiangya Hospital of Central South University, Changsha 410011, Hunan Province, PR China
| | - Lu Shu
- Department of Thoracic Surgery, The Second Xiangya Hospital of Central South University, Changsha 410011, Hunan Province, PR China
| | - Yi Sun
- Department of Pathology, The Second Xiangya Hospital of Central South University, Changsha 410011, Hunan Province, PR China.
| |
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
|
Sallinger M, Grabmayr H, Humer C, Bonhenry D, Romanin C, Schindl R, Derler I. Activation mechanisms and structural dynamics of STIM proteins. J Physiol 2024; 602:1475-1507. [PMID: 36651592 DOI: 10.1113/jp283828] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/11/2023] [Indexed: 01/19/2023] Open
Abstract
The family of stromal interaction molecules (STIM) includes two widely expressed single-pass endoplasmic reticulum (ER) transmembrane proteins and additional splice variants that act as precise ER-luminal Ca2+ sensors. STIM proteins mainly function as one of the two essential components of the so-called Ca2+ release-activated Ca2+ (CRAC) channel. The second CRAC channel component is constituted by pore-forming Orai proteins in the plasma membrane. STIM and Orai physically interact with each other to enable CRAC channel opening, which is a critical prerequisite for various downstream signalling pathways such as gene transcription or proliferation. Their activation commonly requires the emptying of the intracellular ER Ca2+ store. Using their Ca2+ sensing capabilities, STIM proteins confer this Ca2+ content-dependent signal to Orai, thereby linking Ca2+ store depletion to CRAC channel opening. Here we review the conformational dynamics occurring along the entire STIM protein upon store depletion, involving the transition from the quiescent, compactly folded structure into an active, extended state, modulation by a variety of accessory components in the cell as well as the impairment of individual steps of the STIM activation cascade associated with disease.
Collapse
Affiliation(s)
- Matthias Sallinger
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Herwig Grabmayr
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Christina Humer
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Daniel Bonhenry
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Nove Hrady, Czech Republic
| | - Christoph Romanin
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Rainer Schindl
- Gottfried Schatz Research Centre, Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| |
Collapse
|
4
|
Bacsa B, Hopl V, Derler I. Synthetic Biology Meets Ca 2+ Release-Activated Ca 2+ Channel-Dependent Immunomodulation. Cells 2024; 13:468. [PMID: 38534312 DOI: 10.3390/cells13060468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 02/27/2024] [Accepted: 03/05/2024] [Indexed: 03/28/2024] Open
Abstract
Many essential biological processes are triggered by the proximity of molecules. Meanwhile, diverse approaches in synthetic biology, such as new biological parts or engineered cells, have opened up avenues to precisely control the proximity of molecules and eventually downstream signaling processes. This also applies to a main Ca2+ entry pathway into the cell, the so-called Ca2+ release-activated Ca2+ (CRAC) channel. CRAC channels are among other channels are essential in the immune response and are activated by receptor-ligand binding at the cell membrane. The latter initiates a signaling cascade within the cell, which finally triggers the coupling of the two key molecular components of the CRAC channel, namely the stromal interaction molecule, STIM, in the ER membrane and the plasma membrane Ca2+ ion channel, Orai. Ca2+ entry, established via STIM/Orai coupling, is essential for various immune cell functions, including cytokine release, proliferation, and cytotoxicity. In this review, we summarize the tools of synthetic biology that have been used so far to achieve precise control over the CRAC channel pathway and thus over downstream signaling events related to the immune response.
Collapse
Affiliation(s)
- Bernadett Bacsa
- Division of Medical Physics und Biophysics, Medical University of Graz, A-8010 Graz, Austria
| | - Valentina Hopl
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| |
Collapse
|
5
|
Humer C, Radiskovic T, Horváti K, Lindinger S, Groschner K, Romanin C, Höglinger C. Bidirectional Allosteric Coupling between PIP 2 Binding and the Pore of the Oncochannel TRPV6. Int J Mol Sci 2024; 25:618. [PMID: 38203789 PMCID: PMC10779433 DOI: 10.3390/ijms25010618] [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: 12/08/2023] [Revised: 12/31/2023] [Accepted: 01/01/2024] [Indexed: 01/12/2024] Open
Abstract
The epithelial ion channel TRPV6 plays a pivotal role in calcium homeostasis. Channel function is intricately regulated at different stages, involving the lipid phosphatidylinositol-4,5-bisphosphate (PIP2). Given that dysregulation of TRPV6 is associated with various diseases, including different types of cancer, there is a compelling need for its pharmacological targeting. Structural studies provide insights on how TRPV6 is affected by different inhibitors, with some binding to sites else occupied by lipids. These include the small molecule cis-22a, which, however, also binds to and thereby blocks the pore. By combining calcium imaging, electrophysiology and optogenetics, we identified residues within the pore and the lipid binding site that are relevant for regulation by cis-22a and PIP2 in a bidirectional manner. Yet, mutation of the cytosolic pore exit reduced inhibition by cis-22a but preserved sensitivity to PIP2 depletion. Our data underscore allosteric communication between the lipid binding site and the pore and vice versa for most sites along the pore.
Collapse
Affiliation(s)
- Christina Humer
- Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria; (C.H.); (T.R.); (C.R.)
| | - Tamara Radiskovic
- Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria; (C.H.); (T.R.); (C.R.)
| | - Kata Horváti
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, 1117 Budapest, Hungary;
| | - Sonja Lindinger
- Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria; (C.H.); (T.R.); (C.R.)
| | - Klaus Groschner
- Gottfried Schatz Research Center, Division of Biophysics, Medical University of Graz, 8010 Graz, Austria;
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria; (C.H.); (T.R.); (C.R.)
| | - Carmen Höglinger
- Institute of Biophysics, Johannes Kepler University Linz, 4020 Linz, Austria; (C.H.); (T.R.); (C.R.)
| |
Collapse
|
6
|
Boretto C, Actis C, Faris P, Cordero F, Beccuti M, Ferrero G, Muzio G, Moccia F, Autelli R. Tamoxifen Activates Transcription Factor EB and Triggers Protective Autophagy in Breast Cancer Cells by Inducing Lysosomal Calcium Release: A Gateway to the Onset of Endocrine Resistance. Int J Mol Sci 2023; 25:458. [PMID: 38203629 PMCID: PMC10779225 DOI: 10.3390/ijms25010458] [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: 11/30/2023] [Revised: 12/22/2023] [Accepted: 12/24/2023] [Indexed: 01/12/2024] Open
Abstract
Among the several mechanisms accounting for endocrine resistance in breast cancer, autophagy has emerged as an important player. Previous reports have evidenced that tamoxifen (Tam) induces autophagy and activates transcription factor EB (TFEB), which regulates the expression of genes controlling autophagy and lysosomal biogenesis. However, the mechanisms by which this occurs have not been elucidated as yet. This investigation aims at dissecting how TFEB is activated and contributes to Tam resistance in luminal A breast cancer cells. TFEB was overexpressed and prominently nuclear in Tam-resistant MCF7 cells (MCF7-TamR) compared with their parental counterpart, and this was not dependent on alterations of its nucleo-cytoplasmic shuttling. Tam promoted the release of lysosomal Ca2+ through the major transient receptor potential cation channel mucolipin subfamily member 1 (TRPML1) and two-pore channels (TPCs), which caused the nuclear translocation and activation of TFEB. Consistently, inhibiting lysosomal calcium release restored the susceptibility of MCF7-TamR cells to Tam. Our findings demonstrate that Tam drives the nuclear relocation and transcriptional activation of TFEB by triggering the release of Ca2+ from the acidic compartment, and they suggest that lysosomal Ca2+ channels may represent new druggable targets to counteract the onset of autophagy-mediated endocrine resistance in luminal A breast cancer cells.
Collapse
Affiliation(s)
- Cecilia Boretto
- Department of Clinical and Biological Sciences, University of Turin, 10125 Turin, Italy; (C.B.); (C.A.); (G.F.); (G.M.)
| | - Chiara Actis
- Department of Clinical and Biological Sciences, University of Turin, 10125 Turin, Italy; (C.B.); (C.A.); (G.F.); (G.M.)
| | - Pawan Faris
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy;
| | - Francesca Cordero
- Department of Computer Science, University of Turin, 10149 Turin, Italy; (F.C.); (M.B.)
| | - Marco Beccuti
- Department of Computer Science, University of Turin, 10149 Turin, Italy; (F.C.); (M.B.)
| | - Giulio Ferrero
- Department of Clinical and Biological Sciences, University of Turin, 10125 Turin, Italy; (C.B.); (C.A.); (G.F.); (G.M.)
| | - Giuliana Muzio
- Department of Clinical and Biological Sciences, University of Turin, 10125 Turin, Italy; (C.B.); (C.A.); (G.F.); (G.M.)
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, 27100 Pavia, Italy;
| | - Riccardo Autelli
- Department of Clinical and Biological Sciences, University of Turin, 10125 Turin, Italy; (C.B.); (C.A.); (G.F.); (G.M.)
| |
Collapse
|
7
|
Neamtu A, Serban DN, Barritt GJ, Isac DL, Vasiliu T, Laaksonen A, Serban IL. Molecular dynamics simulations reveal the hidden EF-hand of EF-SAM as a possible key thermal sensor for STIM1 activation by temperature. J Biol Chem 2023; 299:104970. [PMID: 37380078 PMCID: PMC10400917 DOI: 10.1016/j.jbc.2023.104970] [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: 02/10/2023] [Revised: 06/07/2023] [Accepted: 06/22/2023] [Indexed: 06/30/2023] Open
Abstract
Intracellular calcium signaling is essential for many cellular processes, including store-operated Ca2+ entry (SOCE), which is initiated by stromal interaction molecule 1 (STIM1) detecting endoplasmic reticulum (ER) Ca2+ depletion. STIM1 is also activated by temperature independent of ER Ca2+ depletion. Here we provide evidence, from advanced molecular dynamics simulations, that EF-SAM may act as a true temperature sensor for STIM1, with the prompt and extended unfolding of the hidden EF-hand subdomain (hEF) even at slightly elevated temperatures, exposing a highly conserved hydrophobic Phe108. Our study also suggests an interplay between Ca2+ and temperature sensing, as both, the canonical EF-hand subdomain (cEF) and the hidden EF-hand subdomain (hEF), exhibit much higher thermal stability in the Ca2+-loaded form compared to the Ca2+-free form. The SAM domain, surprisingly, displays high thermal stability compared to the EF-hands and may act as a stabilizer for the latter. We propose a modular architecture for the EF-hand-SAM domain of STIM1 composed of a thermal sensor (hEF), a Ca2+ sensor (cEF), and a stabilizing domain (SAM). Our findings provide important insights into the mechanism of temperature-dependent regulation of STIM1, which has broad implications for understanding the role of temperature in cellular physiology.
Collapse
Affiliation(s)
- Andrei Neamtu
- Department of Physiology, "Grigore T. Popa" University of Medicine and Pharmacy, Iasi, Romania; Center of Advanced Research in Bionanocojugates and Biopolymers, "Petru Poni" Institute of Macromolecular Chemistry Iasi, Iasi, Romania
| | - Dragomir N Serban
- Department of Physiology, "Grigore T. Popa" University of Medicine and Pharmacy, Iasi, Romania.
| | - Greg J Barritt
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Dragos Lucian Isac
- Center of Advanced Research in Bionanocojugates and Biopolymers, "Petru Poni" Institute of Macromolecular Chemistry Iasi, Iasi, Romania
| | - Tudor Vasiliu
- Center of Advanced Research in Bionanocojugates and Biopolymers, "Petru Poni" Institute of Macromolecular Chemistry Iasi, Iasi, Romania
| | - Aatto Laaksonen
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden; Centre of Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry, Iasi, Romania; State Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing, P. R. China
| | | |
Collapse
|
8
|
Searching for Mechanisms Underlying the Assembly of Calcium Entry Units: The Role of Temperature and pH. Int J Mol Sci 2023; 24:ijms24065328. [PMID: 36982401 PMCID: PMC10049691 DOI: 10.3390/ijms24065328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/24/2023] [Accepted: 02/27/2023] [Indexed: 03/14/2023] Open
Abstract
Store-operated Ca2+ entry (SOCE) is a mechanism that allows muscle fibers to recover external Ca2+, which first enters the cytoplasm andthen, via SERCA pump, also refills the depleted intracellular stores (i.e., the sarcoplasmic reticulum, SR). We recently discovered that SOCE is mediated by Calcium Entry Units (CEUs), intracellular junctions formed by: (i) SR stacks containing STIM1; and (ii) I-band extensions of the transverse tubule (TT) containing Orai1. The number and size of CEUs increase during prolonged muscle activity, though the mechanisms underlying exercise-dependent formation of new CEUs remain to be elucidated. Here, we first subjected isolated extensor digitorum longus (EDL) muscles from wild type mice to an exvivo exercise protocol and verified that functional CEUs can assemble alsoin the absence of blood supply and innervation. Then, we evaluated whetherparameters that are influenced by exercise, such as temperature and pH, may influence the assembly of CEUs. Results collected indicate that higher temperature (36 °C vs. 25 °C) and lower pH (7.2 vs. 7.4) increase the percentage of fibers containing SR stacks, the n. of SR stacks/area, and the elongation of TTs at the I band. Functionally, assembly of CEUs at higher temperature (36 °C) or at lower pH (7.2) correlates with increased fatigue resistance of EDL muscles in the presence of extracellular Ca2+. Taken together, these results indicate that CEUs can assemble in isolated EDL muscles and that temperature and pH are two of the possible regulators of CEU formation.
Collapse
|
9
|
Protasi F, Girolami B, Roccabianca S, Rossi D. Store-operated calcium entry: From physiology to tubular aggregate myopathy. Curr Opin Pharmacol 2023; 68:102347. [PMID: 36608411 DOI: 10.1016/j.coph.2022.102347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 11/30/2022] [Accepted: 12/04/2022] [Indexed: 01/06/2023]
Abstract
Store-Operated Ca2+ entry (SOCE) is recognized as a key mechanism in muscle physiology necessary to refill intracellular Ca2+ stores during sustained muscle activity. For many years the cell structures expected to mediate SOCE in skeletal muscle fibres remained unknown. Recently, the identification of Ca2+ Entry Units (CEUs) in exercised muscle fibres opened new insights into the role of extracellular Ca2+ in muscle contraction and, more generally, in intracellular Ca2+ homeostasis. Accordingly, intracellular Ca2+ unbalance due to alterations in SOCE strictly correlates with muscle disfunction and disease. Mutations in proteins involved in SOCE (STIM1, ORAI1, and CASQ1) have been linked to tubular aggregate myopathy (TAM), a disease that causes muscle weakness and myalgia and is characterized by a typical accumulation of highly ordered and packed membrane tubules originated from the sarcoplasmic reticulum (SR). Achieving a full understanding of the molecular pathways activated by alterations in Ca2+ entry mechanisms is a necessary step to design effective therapies for human SOCE-related disorders.
Collapse
Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy; DMSI, Department of Medicine and Aging Sciences; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy
| | - Barbara Girolami
- CAST, Center for Advanced Studies and Technology; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy; DMSI, Department of Medicine and Aging Sciences; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy
| | - Sara Roccabianca
- DMMS, Department of Molecular and Developmental Medicine; University of Siena, I-53100, Siena Italy
| | - Daniela Rossi
- DMMS, Department of Molecular and Developmental Medicine; University of Siena, I-53100, Siena Italy.
| |
Collapse
|
10
|
Tiffner A, Hopl V, Derler I. CRAC and SK Channels: Their Molecular Mechanisms Associated with Cancer Cell Development. Cancers (Basel) 2022; 15:101. [PMID: 36612099 PMCID: PMC9817886 DOI: 10.3390/cancers15010101] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 12/28/2022] Open
Abstract
Cancer represents a major health burden worldwide. Several molecular targets have been discovered alongside treatments with positive clinical outcomes. However, the reoccurrence of cancer due to therapy resistance remains the primary cause of mortality. Endeavors in pinpointing new markers as molecular targets in cancer therapy are highly desired. The significance of the co-regulation of Ca2+-permeating and Ca2+-regulated ion channels in cancer cell development, proliferation, and migration make them promising molecular targets in cancer therapy. In particular, the co-regulation of the Orai1 and SK3 channels has been well-studied in breast and colon cancer cells, where it finally leads to an invasion-metastasis cascade. Nevertheless, many questions remain unanswered, such as which key molecular components determine and regulate their interplay. To provide a solid foundation for a better understanding of this ion channel co-regulation in cancer, we first shed light on the physiological role of Ca2+ and how this ion is linked to carcinogenesis. Then, we highlight the structure/function relationship of Orai1 and SK3, both individually and in concert, their role in the development of different types of cancer, and aspects that are not yet known in this context.
Collapse
Affiliation(s)
- Adéla Tiffner
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | | | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| |
Collapse
|
11
|
MITF is a novel transcriptional regulator of the calcium sensor STIM1: Significance in physiological melanogenesis. J Biol Chem 2022; 298:102681. [PMID: 36356899 PMCID: PMC9723939 DOI: 10.1016/j.jbc.2022.102681] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/28/2022] [Accepted: 10/31/2022] [Indexed: 11/09/2022] Open
Abstract
Stromal Interaction Molecule1 (STIM1) is an endoplasmic reticulum membrane-localized calcium (Ca2+) sensor that plays a critical role in the store-operated Ca2+ entry (SOCE) pathway. STIM1 regulates a variety of physiological processes and contributes to a plethora of pathophysiological conditions. Several disease states and enhanced biological phenomena are associated with increased STIM1 levels and activity. However, molecular mechanisms driving STIM1 expression remain largely unappreciated. We recently reported that STIM1 expression augments during pigmentation. Nonetheless, the molecular choreography regulating STIM1 expression in melanocytes is completely unexplored. Here, we characterized the molecular events that regulate STIM1 expression during pigmentation. We demonstrate that physiological melanogenic stimuli α-melanocyte stimulating hormone (αMSH) increases STIM1 mRNA and protein levels. Further, αMSH stimulates STIM1 promoter-driven luciferase activity, thereby suggesting transcriptional upregulation of STIM1. We show that downstream of αMSH, microphthalmia-associated transcription factor (MITF) drives STIM1 expression. By performing knockdown and overexpression studies, we corroborated that MITF regulates STIM1 expression and SOCE. Next, we conducted extensive bioinformatics analysis and identified MITF-binding sites on the STIM1 promoter. We validated significance of the MITF-binding sites in controlling STIM1 expression by performing ChIP and luciferase assays with truncated STIM1 promoters. Moreover, we confirmed MITF's role in regulating STIM1 expression and SOCE in primary human melanocytes. Importantly, analysis of publicly available datasets substantiates a positive correlation between STIM1 and MITF expression in sun-exposed tanned human skin, thereby highlighting physiological relevance of this regulation. Taken together, we have identified a novel physiologically relevant molecular pathway that transcriptionally enhances STIM1 expression.
Collapse
|
12
|
Rossi D, Catallo MR, Pierantozzi E, Sorrentino V. Mutations in proteins involved in E-C coupling and SOCE and congenital myopathies. J Gen Physiol 2022; 154:e202213115. [PMID: 35980353 PMCID: PMC9391951 DOI: 10.1085/jgp.202213115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/15/2022] [Accepted: 07/21/2022] [Indexed: 11/24/2022] Open
Abstract
In skeletal muscle, Ca2+ necessary for muscle contraction is stored and released from the sarcoplasmic reticulum (SR), a specialized form of endoplasmic reticulum through the mechanism known as excitation-contraction (E-C) coupling. Following activation of skeletal muscle contraction by the E-C coupling mechanism, replenishment of intracellular stores requires reuptake of cytosolic Ca2+ into the SR by the activity of SR Ca2+-ATPases, but also Ca2+ entry from the extracellular space, through a mechanism called store-operated calcium entry (SOCE). The fine orchestration of these processes requires several proteins, including Ca2+ channels, Ca2+ sensors, and Ca2+ buffers, as well as the active involvement of mitochondria. Mutations in genes coding for proteins participating in E-C coupling and SOCE are causative of several myopathies characterized by a wide spectrum of clinical phenotypes, a variety of histological features, and alterations in intracellular Ca2+ balance. This review summarizes current knowledge on these myopathies and discusses available knowledge on the pathogenic mechanisms of disease.
Collapse
Affiliation(s)
- Daniela Rossi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
- Interdepartmental Program of Molecular Diagnosis and Pathogenetic Mechanisms of Rare Genetic Diseases, Azienda Ospedaliero Universitaria Senese, Siena, Italy
| | - Maria Rosaria Catallo
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Enrico Pierantozzi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
- Interdepartmental Program of Molecular Diagnosis and Pathogenetic Mechanisms of Rare Genetic Diseases, Azienda Ospedaliero Universitaria Senese, Siena, Italy
| |
Collapse
|
13
|
Title: p53 alters intracellular Ca2+ signaling through regulation of TRPM4. Cell Calcium 2022; 104:102591. [DOI: 10.1016/j.ceca.2022.102591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/08/2022] [Accepted: 04/18/2022] [Indexed: 12/11/2022]
|
14
|
Maltan L, Andova AM, Derler I. The Role of Lipids in CRAC Channel Function. Biomolecules 2022; 12:biom12030352. [PMID: 35327543 PMCID: PMC8944985 DOI: 10.3390/biom12030352] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/12/2022] [Accepted: 02/20/2022] [Indexed: 11/28/2022] Open
Abstract
The composition and dynamics of the lipid membrane define the physical properties of the bilayer and consequently affect the function of the incorporated membrane transporters, which also applies for the prominent Ca2+ release-activated Ca2+ ion channel (CRAC). This channel is activated by receptor-induced Ca2+ store depletion of the endoplasmic reticulum (ER) and consists of two transmembrane proteins, STIM1 and Orai1. STIM1 is anchored in the ER membrane and senses changes in the ER luminal Ca2+ concentration. Orai1 is the Ca2+-selective, pore-forming CRAC channel component located in the plasma membrane (PM). Ca2+ store-depletion of the ER triggers activation of STIM1 proteins, which subsequently leads to a conformational change and oligomerization of STIM1 and its coupling to as well as activation of Orai1 channels at the ER-PM contact sites. Although STIM1 and Orai1 are sufficient for CRAC channel activation, their efficient activation and deactivation is fine-tuned by a variety of lipids and lipid- and/or ER-PM junction-dependent accessory proteins. The underlying mechanisms for lipid-mediated CRAC channel modulation as well as the still open questions, are presented in this review.
Collapse
|
15
|
Aishwarya R, Abdullah CS, Remex NS, Alam S, Morshed M, Nitu S, Hartman B, King J, Bhuiyan MAN, Orr AW, Kevil CG, Bhuiyan MS. Molecular Characterization of Skeletal Muscle Dysfunction in Sigma 1 Receptor (Sigmar1) Knockout Mice. THE AMERICAN JOURNAL OF PATHOLOGY 2022; 192:160-177. [PMID: 34710383 PMCID: PMC8759042 DOI: 10.1016/j.ajpath.2021.10.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 09/11/2021] [Accepted: 10/04/2021] [Indexed: 01/03/2023]
Abstract
Sigma 1 receptor (Sigmar1) is a widely expressed, multitasking molecular chaperone protein that plays functional roles in several cellular processes. Mutations in the Sigmar1 gene are associated with several distal neuropathies with strong manifestation in skeletal muscle dysfunction with phenotypes like muscle wasting and atrophy. However, the physiological function of Sigmar1 in skeletal muscle remains unknown. Herein, the physiological role of Sigmar1 in skeletal muscle structure and function in gastrocnemius, quadriceps, soleus, extensor digitorum longus, and tibialis anterior muscles was determined. Quantification of myofiber cross-sectional area showed altered myofiber size distribution and changes in myofiber type in the skeletal muscle of the Sigmar1-/- mice. Interestingly, ultrastructural analysis by transmission electron microscopy showed the presence of abnormal mitochondria, and immunostaining showed derangements in dystrophin localization in skeletal muscles from Sigmar1-/- mice. In addition, myopathy in Sigmar1-/- mice was associated with an increased number of central nuclei, increased collagen deposition, and fibrosis. Functional studies also showed reduced endurance and exercise capacity in the Sigmar1-/- mice without any changes in voluntary locomotion, markers for muscle denervation, and muscle atrophy. Overall, this study shows, for the first time, a potential physiological function of Sigmar1 in maintaining healthy skeletal muscle structure and function.
Collapse
Affiliation(s)
- Richa Aishwarya
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Chowdhury S Abdullah
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Naznin S Remex
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Shafiul Alam
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Mahboob Morshed
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Sadia Nitu
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Brandon Hartman
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Judy King
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | | | - A Wayne Orr
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana; Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Christopher G Kevil
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana; Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana
| | - Md Shenuarin Bhuiyan
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana; Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana.
| |
Collapse
|
16
|
Tiffner A, Hopl V, Schober R, Sallinger M, Grabmayr H, Höglinger C, Fahrner M, Lunz V, Maltan L, Frischauf I, Krivic D, Bhardwaj R, Schindl R, Hediger MA, Derler I. Orai1 Boosts SK3 Channel Activation. Cancers (Basel) 2021; 13:6357. [PMID: 34944977 PMCID: PMC8699475 DOI: 10.3390/cancers13246357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 12/13/2021] [Indexed: 12/20/2022] Open
Abstract
The interplay of SK3, a Ca2+ sensitive K+ ion channel, with Orai1, a Ca2+ ion channel, has been reported to increase cytosolic Ca2+ levels, thereby triggering proliferation of breast and colon cancer cells, although a molecular mechanism has remained elusive to date. We show in the current study, via heterologous protein expression, that Orai1 can enhance SK3 K+ currents, in addition to constitutively bound calmodulin (CaM). At low cytosolic Ca2+ levels that decrease SK3 K+ permeation, co-expressed Orai1 potentiates SK3 currents. This positive feedback mechanism of SK3 and Orai1 is enabled by their close co-localization. Remarkably, we discovered that loss of SK3 channel activity due to overexpressed CaM mutants could be restored by Orai1, likely via its interplay with the SK3-CaM binding site. Mapping for interaction sites within Orai1, we identified that the cytosolic strands and pore residues are critical for a functional communication with SK3. Moreover, STIM1 has a bimodal role in SK3-Orai1 regulation. Under physiological ionic conditions, STIM1 is able to impede SK3-Orai1 interplay by significantly decreasing their co-localization. Forced STIM1-Orai1 activity and associated Ca2+ influx promote SK3 K+ currents. The dynamic regulation of Orai1 to boost endogenous SK3 channels was also determined in the human prostate cancer cell line LNCaP.
Collapse
Affiliation(s)
- Adéla Tiffner
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Valentina Hopl
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Romana Schober
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Matthias Sallinger
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Herwig Grabmayr
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Carmen Höglinger
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Marc Fahrner
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Victoria Lunz
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Lena Maltan
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Irene Frischauf
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Denis Krivic
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Rajesh Bhardwaj
- Department of Nephrology and Hypertension, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland; (R.B.); (M.A.H.)
- Department of Biomedical Research, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland
| | - Rainer Schindl
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Matthias A. Hediger
- Department of Nephrology and Hypertension, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland; (R.B.); (M.A.H.)
- Department of Biomedical Research, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland
| | - Isabella Derler
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| |
Collapse
|
17
|
Höglinger C, Grabmayr H, Maltan L, Horvath F, Krobath H, Muik M, Tiffner A, Renger T, Romanin C, Fahrner M, Derler I. Defects in the STIM1 SOARα2 domain affect multiple steps in the CRAC channel activation cascade. Cell Mol Life Sci 2021; 78:6645-6667. [PMID: 34498097 PMCID: PMC8558294 DOI: 10.1007/s00018-021-03933-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 08/05/2021] [Accepted: 08/27/2021] [Indexed: 01/05/2023]
Abstract
The calcium release-activated calcium (CRAC) channel consists of STIM1, a Ca2+ sensor in the endoplasmic reticulum (ER), and Orai1, the Ca2+ ion channel in the plasma membrane. Ca2+ store depletion triggers conformational changes and oligomerization of STIM1 proteins and their direct interaction with Orai1. Structural alterations include the transition of STIM1 C-terminus from a folded to an extended conformation thereby exposing CAD (CRAC activation domain)/SOAR (STIM1-Orai1 activation region) for coupling to Orai1. In this study, we discovered that different point mutations of F394 in the small alpha helical segment (STIM1 α2) within the CAD/SOAR apex entail a rich plethora of effects on diverse STIM1 activation steps. An alanine substitution (STIM1 F394A) destabilized the STIM1 quiescent state, as evident from its constitutive activity. Single point mutation to hydrophilic, charged amino acids (STIM1 F394D, STIM1 F394K) impaired STIM1 homomerization and subsequent Orai1 activation. MD simulations suggest that their loss of homomerization may arise from altered formation of the CC1α1-SOAR/CAD interface and potential electrostatic interactions with lipid headgroups in the ER membrane. Consistent with these findings, we provide experimental evidence that the perturbing effects of F394D depend on the distance of the apex from the ER membrane. Taken together, our results suggest that the CAD/SOAR apex is in the immediate vicinity of the ER membrane in the STIM1 quiescent state and that different mutations therein can impact the STIM1/Orai1 activation cascade in various manners. Legend: Upon intracellular Ca2+ store depletion of the endoplasmic reticulum (ER), Ca2+ dissociates from STIM1. As a result, STIM1 adopts an elongated conformation and elicits Ca2+ influx from the extracellular matrix (EM) into the cell due to binding to and activation of Ca2+-selective Orai1 channels (left). The effects of three point mutations within the SOARα2 domain highlight the manifold roles of this region in the STIM1/Orai1 activation cascade: STIM1 F394A is active irrespective of the intracellular ER Ca2+ store level, but activates Orai1 channels to a reduced extent (middle). On the other hand, STIM1 F394D/K cannot adopt an elongated conformation upon Ca2+ store-depletion due to altered formation of the CC1α1-SOAR/CAD interface and/or electrostatic interaction of the respective side-chain charge with corresponding opposite charges on lipid headgroups in the ER membrane (right).
Collapse
Affiliation(s)
- Carmen Höglinger
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Herwig Grabmayr
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Lena Maltan
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Ferdinand Horvath
- Institute of Theoretical Physics, Johannes Kepler University Linz, Altenbergerstraße 69, 4040, Linz, Austria
| | - Heinrich Krobath
- Institute of Theoretical Physics, Johannes Kepler University Linz, Altenbergerstraße 69, 4040, Linz, Austria
| | - Martin Muik
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Adela Tiffner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Thomas Renger
- Institute of Theoretical Physics, Johannes Kepler University Linz, Altenbergerstraße 69, 4040, Linz, Austria
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Marc Fahrner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria.
| | - Isabella Derler
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria.
| |
Collapse
|
18
|
Tiffner A, Derler I. Isoform-Specific Properties of Orai Homologues in Activation, Downstream Signaling, Physiology and Pathophysiology. Int J Mol Sci 2021; 22:8020. [PMID: 34360783 PMCID: PMC8347056 DOI: 10.3390/ijms22158020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 11/21/2022] Open
Abstract
Ca2+ ion channels are critical in a variety of physiological events, including cell growth, differentiation, gene transcription and apoptosis. One such essential entry pathway for calcium into the cell is the Ca2+ release-activated Ca2+ (CRAC) channel. It consists of the Ca2+ sensing protein, stromal interaction molecule 1 (STIM1) located in the endoplasmic reticulum (ER) and a Ca2+ ion channel Orai in the plasma membrane. The Orai channel family includes three homologues Orai1, Orai2 and Orai3. While Orai1 is the "classical" Ca2+ ion channel within the CRAC channel complex and plays a universal role in the human body, there is increasing evidence that Orai2 and Orai3 are important in specific physiological and pathophysiological processes. This makes them an attractive target in drug discovery, but requires a detailed understanding of the three Orai channels and, in particular, their differences. Orai channel activation is initiated via Ca2+ store depletion, which is sensed by STIM1 proteins, and induces their conformational change and oligomerization. Upon STIM1 coupling, Orai channels activate to allow Ca2+ permeation into the cell. While this activation mechanism is comparable among the isoforms, they differ by a number of functional and structural properties due to non-conserved regions in their sequences. In this review, we summarize the knowledge as well as open questions in our current understanding of the three isoforms in terms of their structure/function relationship, downstream signaling and physiology as well as pathophysiology.
Collapse
Affiliation(s)
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria;
| |
Collapse
|
19
|
The Orai Pore Opening Mechanism. Int J Mol Sci 2021; 22:ijms22020533. [PMID: 33430308 PMCID: PMC7825772 DOI: 10.3390/ijms22020533] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 12/30/2020] [Accepted: 01/02/2021] [Indexed: 02/07/2023] Open
Abstract
Cell survival and normal cell function require a highly coordinated and precise regulation of basal cytosolic Ca2+ concentrations. The primary source of Ca2+ entry into the cell is mediated by the Ca2+ release-activated Ca2+ (CRAC) channel. Its action is stimulated in response to internal Ca2+ store depletion. The fundamental constituents of CRAC channels are the Ca2+ sensor, stromal interaction molecule 1 (STIM1) anchored in the endoplasmic reticulum, and a highly Ca2+-selective pore-forming subunit Orai1 in the plasma membrane. The precise nature of the Orai1 pore opening is currently a topic of intensive research. This review describes how Orai1 gating checkpoints in the middle and cytosolic extended transmembrane regions act together in a concerted manner to ensure an opening-permissive Orai1 channel conformation. In this context, we highlight the effects of the currently known multitude of Orai1 mutations, which led to the identification of a series of gating checkpoints and the determination of their role in diverse steps of the Orai1 activation cascade. The synergistic action of these gating checkpoints maintains an intact pore geometry, settles STIM1 coupling, and governs pore opening. We describe the current knowledge on Orai1 channel gating mechanisms and summarize still open questions of the STIM1-Orai1 machinery.
Collapse
|
20
|
Tiffner A, Schober R, Höglinger C, Bonhenry D, Pandey S, Lunz V, Sallinger M, Frischauf I, Fahrner M, Lindinger S, Maltan L, Berlansky S, Stadlbauer M, Schindl R, Ettrich R, Romanin C, Derler I. CRAC channel opening is determined by a series of Orai1 gating checkpoints in the transmembrane and cytosolic regions. J Biol Chem 2021; 296:100224. [PMID: 33361160 PMCID: PMC7948504 DOI: 10.1074/jbc.ra120.015548] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/15/2020] [Accepted: 12/22/2020] [Indexed: 12/13/2022] Open
Abstract
The initial activation step in the gating of ubiquitously expressed Orai1 calcium (Ca2+) ion channels represents the activation of the Ca2+-sensor protein STIM1 upon Ca2+ store depletion of the endoplasmic reticulum. Previous studies using constitutively active Orai1 mutants gave rise to, but did not directly test, the hypothesis that STIM1-mediated Orai1 pore opening is accompanied by a global conformational change of all Orai transmembrane domain (TM) helices within the channel complex. We prove that a local conformational change spreads omnidirectionally within the Orai1 complex. Our results demonstrate that these locally induced global, opening-permissive TM motions are indispensable for pore opening and require clearance of a series of Orai1 gating checkpoints. We discovered these gating checkpoints in the middle and cytosolic extended TM domain regions. Our findings are based on a library of double point mutants that contain each one loss-of-function with one gain-of-function point mutation in a series of possible combinations. We demonstrated that an array of loss-of-function mutations are dominant over most gain-of-function mutations within the same as well as of an adjacent Orai subunit. We further identified inter- and intramolecular salt-bridge interactions of Orai subunits as a core element of an opening-permissive Orai channel architecture. Collectively, clearance and synergistic action of all these gating checkpoints are required to allow STIM1 coupling and Orai1 pore opening. Our results unravel novel insights in the preconditions of the unique fingerprint of CRAC channel activation, provide a valuable source for future structural resolutions, and help to understand the molecular basis of disease-causing mutations.
Collapse
Affiliation(s)
- Adéla Tiffner
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Romana Schober
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Carmen Höglinger
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Daniel Bonhenry
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Czech Academy of Sciences, Nove Hrady, Czechia
| | - Saurabh Pandey
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Czech Academy of Sciences, Nove Hrady, Czechia
| | - Victoria Lunz
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Matthias Sallinger
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Irene Frischauf
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Marc Fahrner
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Sonja Lindinger
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Lena Maltan
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Sascha Berlansky
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Michael Stadlbauer
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Rainer Schindl
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Rudiger Ettrich
- College of Biomedical Sciences, Larkin University, Miami, Florida, USA; Faculty of Mathematics and Physics, Charles University, Prague, Czechia; Department of Cellular Biology & Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, USA
| | - Christoph Romanin
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria.
| |
Collapse
|
21
|
Grabmayr H, Romanin C, Fahrner M. STIM Proteins: An Ever-Expanding Family. Int J Mol Sci 2020; 22:E378. [PMID: 33396497 PMCID: PMC7795233 DOI: 10.3390/ijms22010378] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 12/20/2020] [Accepted: 12/26/2020] [Indexed: 02/06/2023] Open
Abstract
Stromal interaction molecules (STIM) are a distinct class of ubiquitously expressed single-pass transmembrane proteins in the endoplasmic reticulum (ER) membrane. Together with Orai ion channels in the plasma membrane (PM), they form the molecular basis of the calcium release-activated calcium (CRAC) channel. An intracellular signaling pathway known as store-operated calcium entry (SOCE) is critically dependent on the CRAC channel. The SOCE pathway is activated by the ligand-induced depletion of the ER calcium store. STIM proteins, acting as calcium sensors, subsequently sense this depletion and activate Orai ion channels via direct physical interaction to allow the influx of calcium ions for store refilling and downstream signaling processes. This review article is dedicated to the latest advances in the field of STIM proteins. New results of ongoing investigations based on the recently published functional data as well as structural data from nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations are reported and complemented with a discussion of the latest developments in the research of STIM protein isoforms and their differential functions in regulating SOCE.
Collapse
Affiliation(s)
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria;
| | - Marc Fahrner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria;
| |
Collapse
|
22
|
Waldherr L, Tiffner A, Mishra D, Sallinger M, Schober R, Frischauf I, Schmidt T, Handl V, Sagmeister P, Köckinger M, Derler I, Üçal M, Bonhenry D, Patz S, Schindl R. Blockage of Store-Operated Ca 2+ Influx by Synta66 is Mediated by Direct Inhibition of the Ca 2+ Selective Orai1 Pore. Cancers (Basel) 2020; 12:E2876. [PMID: 33036292 PMCID: PMC7600887 DOI: 10.3390/cancers12102876] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/29/2020] [Accepted: 09/30/2020] [Indexed: 12/14/2022] Open
Abstract
The Ca2+ sensor STIM1 and the Ca2+ channel Orai1 that form the store-operated Ca2+ (SOC) channel complex are key targets for drug development. Selective SOC inhibitors are currently undergoing clinical evaluation for the treatment of auto-immune and inflammatory responses and are also deemed promising anti-neoplastic agents since SOC channels are linked with enhanced cancer cell progression. Here, we describe an investigation of the site of binding of the selective inhibitor Synta66 to the SOC channel Orai1 using docking and molecular dynamics simulations, and live cell recordings. Synta66 binding was localized to the extracellular site close to the transmembrane (TM)1 and TM3 helices and the extracellular loop segments, which, importantly, are adjacent to the Orai1-selectivity filter. Synta66-sensitivity of the Orai1 pore was, in fact, diminished by both Orai1 mutations affecting Ca2+ selectivity and permeation of Na+ in the absence of Ca2+. Synta66 also efficiently blocked SOC in three glioblastoma cell lines but failed to interfere with cell viability, division and migration. These experiments provide new structural and functional insights into selective drug inhibition of the Orai1 Ca2+ channel by a high-affinity pore blocker.
Collapse
Affiliation(s)
- Linda Waldherr
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (L.W.); (R.S.); (T.S.)
| | - Adela Tiffner
- Institute of Biophysics, JKU Life Science Centre, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (M.S.); (I.F.); (I.D.)
| | - Deepti Mishra
- Centre for Nanobiology and Structural Biology, Academy of Sciences of the Czech Republic, 373 33 Nové Hrady, Czech Republic;
| | - Matthias Sallinger
- Institute of Biophysics, JKU Life Science Centre, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (M.S.); (I.F.); (I.D.)
| | - Romana Schober
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (L.W.); (R.S.); (T.S.)
- Institute of Biophysics, JKU Life Science Centre, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (M.S.); (I.F.); (I.D.)
| | - Irene Frischauf
- Institute of Biophysics, JKU Life Science Centre, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (M.S.); (I.F.); (I.D.)
| | - Tony Schmidt
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (L.W.); (R.S.); (T.S.)
| | - Verena Handl
- Department of Neurosurgery, Medical University of Graz, A-8010 Graz, Austria; (V.H.); (M.Ü.)
| | - Peter Sagmeister
- Institute of Chemistry, University of Graz, Heinrichstraße 28, A-8010 Graz, Austria; (P.S.); (M.K.)
| | - Manuel Köckinger
- Institute of Chemistry, University of Graz, Heinrichstraße 28, A-8010 Graz, Austria; (P.S.); (M.K.)
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Centre, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (M.S.); (I.F.); (I.D.)
| | - Muammer Üçal
- Department of Neurosurgery, Medical University of Graz, A-8010 Graz, Austria; (V.H.); (M.Ü.)
| | - Daniel Bonhenry
- Centre for Nanobiology and Structural Biology, Academy of Sciences of the Czech Republic, 373 33 Nové Hrady, Czech Republic;
| | - Silke Patz
- Department of Neurosurgery, Medical University of Graz, A-8010 Graz, Austria; (V.H.); (M.Ü.)
| | - Rainer Schindl
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (L.W.); (R.S.); (T.S.)
- Institute of Biophysics, JKU Life Science Centre, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (M.S.); (I.F.); (I.D.)
| |
Collapse
|