A pathogenic human Orai1 mutation unmasks STIM1-independent rapid inactivation of Orai1 channels.
A pathogenic human Orai1 mutation unmasks STIM1-independent rapid inactivation of Orai1 channels.
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DOI：
10.7554/elife.82281
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发表时间：
2023-02-20
期刊：
影响因子：
7.7
通讯作者：
Prakriya M
中科院分区：
文献类型：
--
作者：
Yeung PS;Yamashita M;Prakriya M
Ca 2+释放激活的Ca 2+（CRAC）通道通过通道蛋白Orai 1和内质网Ca 2+传感器STIM 1之间的直接物理相互作用激活。CRAC通道的标志是快速Ca 2+依赖性失活（CDI），其提供负反馈以限制Ca 2+通过CRAC通道进入。虽然STIM 1被认为是CDI的关键，但其分子机制仍不清楚。在这里，我们研究了一个知之甚少的功能获得性（GOF）人类Orai 1疾病突变，L138 F，导致管状聚集性肌病。通过成对突变分析，我们确定在不存在STIM 1的情况下，位于孔螺旋上的L138或邻近T92基因座上的大型氨基酸取代会诱发高度Ca 2+选择性电流。我们发现L138致病突变的GOF表型是由于L138和T92之间的空间冲突而产生的。令人惊讶的是，强烈激活的L138和T92突变在缺乏STIM 1的情况下显示出CDI，这与CDI需要STIM 1的流行观点相矛盾。组成型开放T92 W和L138 F突变体的CDI显示出增强的细胞内Ca 2+敏感性，其通过向细胞中重新添加STIM 1而正常化。Orai 1 C-末端的截短降低了T92 W CDI，表明Orai 1 C-末端对CDI的关键作用。总体而言，这些结果确定了疾病表型的分子基础，对Orai 1通道的激活和失活具有广泛意义。
Ca2+ release-activated Ca2+ (CRAC) channels are activated by direct physical interactions between Orai1, the channel protein, and STIM1, the endoplasmic reticulum Ca2+ sensor. A hallmark of CRAC channels is fast Ca2+-dependent inactivation (CDI) which provides negative feedback to limit Ca2+ entry through CRAC channels. Although STIM1 is thought to be essential for CDI, its molecular mechanism remains largely unknown. Here, we examined a poorly understood gain-of-function (GOF) human Orai1 disease mutation, L138F, that causes tubular aggregate myopathy. Through pairwise mutational analysis, we determine that large amino acid substitutions at either L138 or the neighboring T92 locus located on the pore helix evoke highly Ca2+-selective currents in the absence of STIM1. We find that the GOF phenotype of the L138 pathogenic mutation arises due to steric clash between L138 and T92. Surprisingly, strongly activating L138 and T92 mutations showed CDI in the absence of STIM1, contradicting prevailing views that STIM1 is required for CDI. CDI of constitutively open T92W and L138F mutants showed enhanced intracellular Ca2+ sensitivity, which was normalized by re-adding STIM1 to the cells. Truncation of the Orai1 C-terminus reduced T92W CDI, indicating a key role for the Orai1 C-terminus for CDI. Overall, these results identify the molecular basis of a disease phenotype with broad implications for activation and inactivation of Orai1 channels.
突变 L138F/L210F 对 Orai 通道的影响：分子动力学模拟研究
影响因子：
5
作者：
Zhang X;Yu H;Liu X;Song C
通讯作者：
Song C