Ben-Kasus Nissim Tsipi, Zhang Xuexin, Elazar Assaf, Roy Soumitra, Stolwijk Judith A, Zhou Yandong, Motiani Rajender K, Gueguinou Maxime, Hempel Nadine, Hershfinkel Michal, Gill Donald L, Trebak Mohamed, Sekler Israel
The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA.
EMBO J. 2017 Mar 15;36(6):797-815. doi: 10.15252/embj.201592481. Epub 2017 Feb 20.
Mitochondria exert important control over plasma membrane (PM) Orai1 channels mediating store-operated Ca entry (SOCE). Although the sensing of endoplasmic reticulum (ER) Ca stores by STIM proteins and coupling to Orai1 channels is well understood, how mitochondria communicate with Orai1 channels to regulate SOCE activation remains elusive. Here, we reveal that SOCE is accompanied by a rise in cytosolic Na that is critical in activating the mitochondrial Na/Ca exchanger (NCLX) causing enhanced mitochondrial Na uptake and Ca efflux. Omission of extracellular Na prevents the cytosolic Na rise, inhibits NCLX activity, and impairs SOCE and Orai1 channel current. We show further that SOCE activates a mitochondrial redox transient which is dependent on NCLX and is required for preventing Orai1 inactivation through oxidation of a critical cysteine (Cys195) in the third transmembrane helix of Orai1. We show that mitochondrial targeting of catalase is sufficient to rescue redox transients, SOCE, and Orai1 currents in NCLX-deficient cells. Our findings identify a hitherto unknown NCLX-mediated pathway that coordinates Na and Ca signals to effect mitochondrial redox control over SOCE.
线粒体对介导储存性钙内流（SOCE）的质膜（PM）Orai1通道发挥着重要的调控作用。尽管STIM蛋白对内质网（ER）钙库的感知以及与Orai1通道的偶联已得到充分了解，但线粒体如何与Orai1通道通讯以调节SOCE激活仍不清楚。在此，我们揭示SOCE伴随着胞质钠的升高，这对于激活线粒体钠/钙交换体（NCLX）至关重要，会导致线粒体钠摄取增加和钙外流增强。去除细胞外钠可防止胞质钠升高，抑制NCLX活性，并损害SOCE和Orai1通道电流。我们进一步表明，SOCE激活了一种线粒体氧化还原瞬变，该瞬变依赖于NCLX，并且是通过氧化Orai1第三个跨膜螺旋中的关键半胱氨酸（Cys195）来防止Orai1失活所必需的。我们表明，过氧化氢酶的线粒体靶向足以挽救NCLX缺陷细胞中的氧化还原瞬变、SOCE和Orai1电流。我们的研究结果确定了一条迄今未知的NCLX介导的途径，该途径协调钠和钙信号以实现线粒体对SOCE的氧化还原控制。
