Title | Stimulated association of STIM1 and Orai1 is regulated by the balance of PtdIns(4,5)P₂ between distinct membrane pools. |
Publication Type | Journal Article |
Year of Publication | 2011 |
Authors | Calloway N, Owens T, Corwith K, Rodgers W, Holowka D, Baird B |
Journal | J Cell Sci |
Volume | 124 |
Issue | Pt 15 |
Pagination | 2602-10 |
Date Published | 2011 Aug 01 |
ISSN | 1477-9137 |
Keywords | Animals, Calcium, Calcium Channels, Cell Line, Tumor, Membrane Glycoproteins, Microscopy, Confocal, ORAI1 Protein, Phosphatidylinositol 4,5-Diphosphate, Phosphotransferases (Alcohol Group Acceptor), Protein Binding, Protein Isoforms, Rats, Stromal Interaction Molecule 1 |
Abstract | We have previously shown that PIP5KIβ and PIP5KIγ generate functionally distinct pools of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] important for antigen-stimulated Ca(2+) entry in mast cells. In the present study, we find that association of the endoplasmic reticulum (ER) Ca(2+) sensor, STIM1, and the store-operated Ca(2+) channel, Orai1, stimulated by thapsigargin-mediated ER store depletion, is enhanced by overexpression of PIP5KIβ and inhibited by overexpression of PIP5KIγ. These different PIP5KI isoforms cause differential enhancement of PtdIns(4,5)P(2) in detergent-resistant membrane (DRM) fractions, which comprise ordered lipid regions, and detergent-solubilized membrane (DSM) fractions, which comprise disordered lipid regions. Consistent with these results, the inositol 5-phosphatase L10-Inp54p, which is targeted to ordered lipids, decreases PtdIns(4,5)P(2) in the DRM fraction and inhibits thapsigargin-stimulated STIM1-Orai1 association and store-operated Ca(2+) entry, whereas the inositol 5-phosphatase S15-Inp54p, which is targeted to disordered lipids, decreases PtdIns(4,5)P(2) in the DSM fraction and enhances STIM1-Orai1 association. Removal of either the STIM1 C-terminal polylysine sequence (amino acids 677-685) or an N-terminal polyarginine sequence in Orai1 (amino acids 28-33) eliminates this differential sensitivity of STIM1-Orai1 association to PtdIns(4,5)P(2) in the distinctive membrane domains. Our results are consistent with a model of PtdIns(4,5)P(2) balance, in which store-depletion-stimulated STIM1-Orai1 association is positively regulated by the ordered lipid pool of PtdIns(4,5)P(2) and negatively regulated by PtdIns(4,5)P(2) in disordered lipid domains. |
DOI | 10.1242/jcs.084178 |
Alternate Journal | J Cell Sci |
PubMed ID | 21750194 |
PubMed Central ID | PMC3138702 |
Grant List | R01 AI022449 / AI / NIAID NIH HHS / United States T32 GM008500 / GM / NIGMS NIH HHS / United States AI022449 / AI / NIAID NIH HHS / United States |
Related Faculty:
William Rodgers, M.D., Ph.D.