Missense mutation in immunodeficient patients shows the multifunctional roles of coiled-coil domain 3 (CC3) in STIM1 activation
Missense mutation in immunodeficient patients shows the multifunctional roles of coiled-coil domain 3 (CC3) in STIM1 activation
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DOI：
10.1073/pnas.1418852112
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发表时间：
2015-05-12
影响因子：
11.1
通讯作者：
Feske, Stefan
中科院分区：
文献类型：
--
作者：
Maus, Mate;Jairaman, Amit;Feske, Stefan
钙池操纵的钙内流（SOCE）是一种普遍的钙内流途径，对许多细胞类型的功能都很重要。SOCE发生在内质网（ER）Ca 2+储存耗尽时，并依赖于质膜（PM）Ca 2+通道ORAI 1和ER Ca 2+传感器基质相互作用分子（STIM）1之间的复杂分子相互作用。ORAI 1或STIM 1基因无效突变的患者表现为严重的联合免疫缺陷（SCID）样疾病。在这里，我们描述了人类患者中功能丧失的STIM 1突变（R429 C）消除SOCE的分子机制。R429位于STIM 1的胞质C末端的第三卷曲螺旋（CC 3）结构域中。R429的突变使CC 3结构不稳定并改变STIM 1 C末端的构象，从而释放促进STIM 1募集到ER-PM连接的多碱基结构域。然而，该突变也损害了细胞质STIM 1寡聚化并消除了STIM 1-ORAI 1相互作用。因此，尽管其组成性定位在ER-PM交界处，突变STIM 1未能激活SOCE。我们的研究结果表明，CC 3结构域在调节分子内和分子间STIM 1相互作用中的多功能作用，这些相互作用控制（i）STIM 1从静止状态到活性构象状态的转变，（ii）细胞质STIM 1寡聚化，以及（iii）STIM 1-ORAI 1结合所需的ORAI 1激活。
Store-operated Ca2+ entry ( SOCE) is a universal Ca2+ influx pathway that is important for the function of many cell types. SOCE occurs upon depletion of endoplasmic reticulum (ER) Ca2+ stores and relies on a complex molecular interplay between the plasma membrane (PM) Ca2+ channel ORAI1 and the ER Ca2+ sensor stromal interaction molecule (STIM) 1. Patients with null mutations in ORAI1 or STIM1 genes present with severe combined immunodeficiency (SCID)-like disease. Here, we describe the molecular mechanisms by which a loss-of-function STIM1 mutation (R429C) in human patients abolishes SOCE. R429 is located in the third coiled-coil (CC3) domain of the cytoplasmic C terminus of STIM1. Mutation of R429 destabilizes the CC3 structure and alters the conformation of the STIM1 C terminus, thereby releasing a polybasic domain that promotes STIM1 recruitment to ER-PM junctions. However, the mutation also impairs cytoplasmic STIM1 oligomerization and abolishes STIM1-ORAI1 interactions. Thus, despite its constitutive localization at ER-PM junctions, mutant STIM1 fails to activate SOCE. Our results demonstrate multifunctional roles of the CC3 domain in regulating intra-and intermolecular STIM1 interactions that control (i) transition of STIM1 from a quiescent to an active conformational state, (ii) cytoplasmic STIM1 oligomerization, and (iii) STIM1-ORAI1 binding required for ORAI1 activation.