STIM protein coupling in the activation of Orai channels

Youjun Wang, Xiaoxiang Deng, Yandong Zhou, Eunan Hendron, Salvatore Mancarella, Michael F. Ritchie, Xiang D. Tang, Yoshihiro Baba, Tomohiro Kurosaki, Yasuo Mori, Jonathan Soboloff, Donald L. Gill

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97 Citations (Scopus)

Abstract

STIM proteins are sensors of endoplasmic reticulum (ER) luminal Ca 2+ changes and rapidly translocate into near plasma membrane (PM) junctions to activate Ca 2+ entry through the Orai family of highly Ca 2+-selective "store-operated" channels (SOCs). Dissecting the STIM-Orai coupling process is restricted by the abstruse nature of the ER-PM junctional domain. To overcome this problem, we studied coupling by using STIM chimera and cytoplasmic C-terminal domains of STIM1 and STIM2 (S1ct and S2ct) and identifying a fundamental action of the powerful SOC modifier, 2-aminoethoxy- diphenyl borate (2-APB), the mechanism of which has eluded recent scrutiny. We reveal that 2-APB induces profound, rapid, and direct interactions between S1ct or S2ct and Orai1, effecting full Ca 2+ release-activated Ca 2+ (CRAC) current activation. The short 235-505 S1ct coiled-coil region was sufficient for functional Orail coupling. YFP-tagged S1ct or S2ct fragments cleared from the cytosol seconds after 2-APB addition, binding avidly to Orai1-CFP with a rapid increase in FRET and transiently increasing CRAC current 200-fold above basal levels. Functional S1ct-Orai1 coupling occurred in STIM1/STIM2-/" DT40 chicken B cells, indicating ct fragments operate independently of native STIM proteins. The 2-APB-induced S1ct-Orai1 and S2-ct-Orai1 complexes undergo rapid reorganization into discrete colocalized PM clusters, which remain stable for >100 s, well beyond CRAC activation and subsequent deactivation. In addition to defining 2-APB's action, the locked STIMct-Orai complex provides a potentially useful probe to structurally examine coupling.

Original languageEnglish
Pages (from-to)7391-7396
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume106
Issue number18
DOIs
Publication statusPublished - May 5 2009

All Science Journal Classification (ASJC) codes

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    Wang, Y., Deng, X., Zhou, Y., Hendron, E., Mancarella, S., Ritchie, M. F., Tang, X. D., Baba, Y., Kurosaki, T., Mori, Y., Soboloff, J., & Gill, D. L. (2009). STIM protein coupling in the activation of Orai channels. Proceedings of the National Academy of Sciences of the United States of America, 106(18), 7391-7396. https://doi.org/10.1073/pnas.0900293106