Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; Institute of Cardiovascular Disease, Nantong University, Nantong, Jiangsu, China.
Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.
J Mol Biol. 2018 Jun 8;430(12):1773-1785. doi: 10.1016/j.jmb.2018.04.028. Epub 2018 Apr 27.
Store-operated Ca entry (SOCE) mediated by stromal interacting molecule-1 (STIM1) and Orai1 represents a major route of Ca entry in mammalian cells and is initiated by STIM1 oligomerization in the endoplasmic or sarcoplasmic reticulum. However, the effects of nitric oxide (NO) on STIM1 function are unknown. Neuronal NO synthase is located in the sarcoplasmic reticulum of cardiomyocytes. Here, we show that STIM1 is susceptible to S-nitrosylation. Neuronal NO synthase deficiency or inhibition enhanced Ca release-activated Ca channel current (I) and SOCE in cardiomyocytes. Consistently, NO donor S-nitrosoglutathione inhibited STIM1 puncta formation and I in HEK293 cells, but this effect was absent in cells expressing the Cys49Ser/Cys56Ser STIM1 double mutant. Furthermore, NO donors caused Cys49- and Cys56-specific structural changes associated with reduced protein backbone mobility, increased thermal stability and suppressed Ca depletion-dependent oligomerization of the luminal Ca-sensing region of STIM1. Collectively, our data show that S-nitrosylation of STIM1 suppresses oligomerization via enhanced luminal domain stability and rigidity and inhibits SOCE in cardiomyocytes.
钙库操纵性钙内流（SOCE）由基质相互作用分子-1（STIM1）和 Orai1 介导，是哺乳动物细胞中钙内流的主要途径，其启动是内质网或肌浆网中 STIM1 寡聚化。然而，一氧化氮（NO）对 STIM1 功能的影响尚不清楚。神经元型一氧化氮合酶位于心肌细胞的肌浆网中。在这里，我们表明 STIM1 易发生 S-亚硝基化。神经元型一氧化氮合酶缺乏或抑制增强了心肌细胞中的钙释放激活钙通道电流（I）和 SOCE。一致地，NO 供体 S-亚硝基谷胱甘肽抑制了 HEK293 细胞中 STIM1 斑点的形成和 I，但在表达 Cys49Ser/Cys56Ser STIM1 双突变体的细胞中，这种作用不存在。此外，NO 供体导致 Cys49-和 Cys56-特异性结构变化，与蛋白骨架流动性降低、热稳定性增加和抑制钙耗竭依赖性 STIM1 腔敏感区寡聚化有关。总之，我们的数据表明，STIM1 的 S-亚硝基化通过增强腔域稳定性和刚性来抑制寡聚化，并抑制心肌细胞中的 SOCE。
