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Role of phosphoinositides in STIM1 dynamics and store-operated calcium entry.
Biochem J. 2009 Dec 14; 425(1):159-68.BJ

Abstract

Ca2+ entry through store-operated Ca2+ channels involves the interaction at ER-PM (endoplasmic reticulum-plasma membrane) junctions of STIM (stromal interaction molecule) and Orai. STIM proteins are sensors of the luminal ER Ca2+ concentration and, following depletion of ER Ca2+, they oligomerize and translocate to ER-PM junctions where they form STIM puncta. Direct binding to Orai proteins activates their Ca2+ channel function. It has been suggested that an additional interaction of the C-terminal polybasic domain of STIM1 with PM phosphoinositides could contribute to STIM1 puncta formation prior to binding to Orai. In the present study, we investigated the role of phosphoinositides in the formation of STIM1 puncta and SOCE (store-operated Ca2+ entry) in response to store depletion. Treatment of HeLa cells with inhibitors of PI3K (phosphatidylinositol 3-kinase) and PI4K (phosphatidylinositol 4-kinase) (wortmannin and LY294002) partially inhibited formation of STIM1 puncta. Additional rapid depletion of PtdIns(4,5)P2 resulted in more substantial inhibition of the translocation of STIM1-EYFP (enhanced yellow fluorescent protein) into puncta. The inhibition was extensive at a concentration of LY294002 (50 microM) that should primarily inhibit PI3K, consistent with a major role for PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in puncta formation. Depletion of phosphoinositides also inhibited SOCE based on measurement of the rise in intracellular Ca2+ concentration after store depletion. Overexpression of Orai1 resulted in a recovery of translocation of STMI1 into puncta following phosphoinositide depletion and, under these conditions, SOCE was increased to above control levels. These observations support the idea that phosphoinositides are not essential but contribute to STIM1 accumulation at ER-PM junctions with a second translocation mechanism involving direct STIM1-Orai interactions.

Authors+Show Affiliations

The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19843011

Citation

Walsh, Ciara M., et al. "Role of Phosphoinositides in STIM1 Dynamics and Store-operated Calcium Entry." The Biochemical Journal, vol. 425, no. 1, 2009, pp. 159-68.
Walsh CM, Chvanov M, Haynes LP, et al. Role of phosphoinositides in STIM1 dynamics and store-operated calcium entry. Biochem J. 2009;425(1):159-68.
Walsh, C. M., Chvanov, M., Haynes, L. P., Petersen, O. H., Tepikin, A. V., & Burgoyne, R. D. (2009). Role of phosphoinositides in STIM1 dynamics and store-operated calcium entry. The Biochemical Journal, 425(1), 159-68. https://doi.org/10.1042/BJ20090884
Walsh CM, et al. Role of Phosphoinositides in STIM1 Dynamics and Store-operated Calcium Entry. Biochem J. 2009 Dec 14;425(1):159-68. PubMed PMID: 19843011.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Role of phosphoinositides in STIM1 dynamics and store-operated calcium entry. AU - Walsh,Ciara M, AU - Chvanov,Michael, AU - Haynes,Lee P, AU - Petersen,Ole H, AU - Tepikin,Alexei V, AU - Burgoyne,Robert D, Y1 - 2009/12/14/ PY - 2009/10/22/entrez PY - 2009/10/22/pubmed PY - 2010/1/22/medline SP - 159 EP - 68 JF - The Biochemical journal JO - Biochem J VL - 425 IS - 1 N2 - Ca2+ entry through store-operated Ca2+ channels involves the interaction at ER-PM (endoplasmic reticulum-plasma membrane) junctions of STIM (stromal interaction molecule) and Orai. STIM proteins are sensors of the luminal ER Ca2+ concentration and, following depletion of ER Ca2+, they oligomerize and translocate to ER-PM junctions where they form STIM puncta. Direct binding to Orai proteins activates their Ca2+ channel function. It has been suggested that an additional interaction of the C-terminal polybasic domain of STIM1 with PM phosphoinositides could contribute to STIM1 puncta formation prior to binding to Orai. In the present study, we investigated the role of phosphoinositides in the formation of STIM1 puncta and SOCE (store-operated Ca2+ entry) in response to store depletion. Treatment of HeLa cells with inhibitors of PI3K (phosphatidylinositol 3-kinase) and PI4K (phosphatidylinositol 4-kinase) (wortmannin and LY294002) partially inhibited formation of STIM1 puncta. Additional rapid depletion of PtdIns(4,5)P2 resulted in more substantial inhibition of the translocation of STIM1-EYFP (enhanced yellow fluorescent protein) into puncta. The inhibition was extensive at a concentration of LY294002 (50 microM) that should primarily inhibit PI3K, consistent with a major role for PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in puncta formation. Depletion of phosphoinositides also inhibited SOCE based on measurement of the rise in intracellular Ca2+ concentration after store depletion. Overexpression of Orai1 resulted in a recovery of translocation of STMI1 into puncta following phosphoinositide depletion and, under these conditions, SOCE was increased to above control levels. These observations support the idea that phosphoinositides are not essential but contribute to STIM1 accumulation at ER-PM junctions with a second translocation mechanism involving direct STIM1-Orai interactions. SN - 1470-8728 UR - https://www.unboundmedicine.com/medline/citation/19843011/Role_of_phosphoinositides_in_STIM1_dynamics_and_store_operated_calcium_entry_ L2 - https://portlandpress.com/biochemj/article-lookup/doi/10.1042/BJ20090884 DB - PRIME DP - Unbound Medicine ER -