title: Retrograde regulation of STIM1-Orai1 interaction and store-operated Ca2+ entry by calsequestrin.
abstract: Interaction between the endoplasmic reticulum (ER)-located stromal interaction molecue1 (STIM1) and the plasma membrane-located Ca(2+) channel subunit, Orai1, underlies store-operated Ca(2+) entry (SOCE). Calsequestrin1 (CSQ1), a sarcoplasmic reticulum Ca(2+) buffering protein, inhibits SOCE, but the mechanism of action is unknown. We identified an interaction between CSQ1 and STIM1 in HEK293 cells. An increase in monomeric CSQ1 induced by depleted Ca(2+) stores, or trifluoperazine (TFP), a blocker of CSQ folding and aggregation, enhanced the CSQ1-STIM1 interaction. In cells with Ca(2+) stores depleted, TFP further increased CSQ1 monomerization and CSQ1-STIM1 interaction, but reduced the association of STIM1 with Orai1 and SOCE. Over-expression of CSQ1 or a C-terminal (amino acid 388-396) deletion mutant significantly promoted the association of CSQ1 with STIM1, but suppressed both STIM1-Orai1 interaction and SOCE, while over-expression of the C-terminal (amino acid 362-396) deletion mutant had no effect. The physical interaction between low polymeric forms of CSQ1 and STIM1 likely acts by interfering with STIM1 oligimerization and inhibits STIM1-Orai1 interaction, providing a brake to SOCE under physiological conditions. This novel regulatory mechanism for SOCE may also contribute to the pathological Ca(2+) overload in calsequestrin deficient diseases, such as malignant hyperthermia and ventricular tachycardia.
authors.affiliation: Department of Pharmacology, Capital Medical University, Beijing 100069, P.R. China.
authors.forename: Limin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, Capital Medical University, Beijing 100069, P.R. China.
authors.forename: Lane
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, Capital Medical University, Beijing 100069, P.R. China.
authors.forename: Shu
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Pharmacology, Capital Medical University, Beijing 100069, P.R. China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Department of Pharmacology, Capital Medical University, Beijing 100069, P.R. China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Yan
authors.affiliation: Department of Pharmacology, Capital Medical University, Beijing 100069, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, Capital Medical University, Beijing 100069, P.R. China.
authors.forename: Haoyang
authors.initials: H
authors.lastname: Wang
authors.affiliation: Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Putney
authors.affiliation: Department of Pharmacology, Capital Medical University, Beijing 100069, P.R. China.
authors.forename: Dali
authors.initials: D
authors.lastname: Luo
mesh_terms: D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002155:Calsequestrin / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D000071740:ORAI1 Protein; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D000071737:Stromal Interaction Molecule 1
chemical_list: D015220:Calcium Channels; D002155:Calsequestrin; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D002118:Calcium