Mechanism of different spatial distributions of Caenorhabditis elegans and human STIM1 at resting state
Mechanism of different spatial distributions of Caenorhabditis elegans and human STIM1 at resting state
复制标题
静息状态下秀丽隐杆线虫和人STIM1不同空间分布的机制
DOI：
10.1016/j.ceca.2008.06.005
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发表时间：
2009-01-01
期刊：
影响因子：
4
通讯作者：
Xu, Pingyong
中科院分区：
文献类型：
--
作者：
Gao, Shangbang;Fan, Yong;Xu, Pingyong
最近的研究已经确定STIM 1和Orai 1是Ca 2+释放激活的Ca 2+（CRAC）通道的重要和保守的组成部分。然而，为什么STIM 1表现出不同的分布在线虫线虫和人细胞内质网（ER）钙库耗尽之前，尚未澄清。与人STIM 1（H.STIM1）的弥漫性ER分布相比，我们发现C.当在HEK 293细胞中表达时，线虫STIM 1（C. STIM 1）在Ca 2+库耗尽之前在细胞周边的斑点中预寡聚化。有趣的是，这些C.STIM1斑点不能诱导C. Orai 1（C.Orai1），而在静止细胞中未检测到CRAC电流。然而，在存储耗尽时，C.Orai1和C.STIM1作为一对在本地感测存储耗尽信号并激活CRAC通道。我们用H.STIM1的N-末端替换C.STIM1的N-末端（H-C. STIM 1），这导致了点前静息定位。相比之下，通过用H.STIM1的C-末端替换C.STIM1的C-末端，我们制备了嵌合蛋白（C.STIM1-H），其在静息状态下表现出两种分布特征，如H.STIM1的弥散ER模式和大聚集体。综上所述，我们的研究结果表明：（1）尽管C.线虫STIM 1和人STIM 1在HEK 293细胞中的空间分布不同;（2）在没有存储耗尽的情况下，C.STIM1在外周位点的斑点不足以聚集和激活C.Orai1;（3）C.STIM1和H.STIM1在静息状态下的不同分布由STIM 1的胞质区域决定。(C)2008爱思唯尔有限公司版权所有。
Recent studies have identified STIM1 and Orai1 as essential and conserved components of the Ca2+ release-activated Ca2+ (CRAC) channel. However, the reason STIM1 exhibits different distributions in nematode Caenorhabditis elegans and in human cells before endoplasmic reticulum (ER) calcium store depletion has not been clarified. Compared to the diffuse ER distribution of human STIM1 (H.STIM1), we found that C. elegans STIM1 (C.STIM1) was preoligomerized in puncta at the cell periphery before Ca2+ store depletion when expressed in HEK293 cells. Interestingly, these C.STIM1 puncta failed to induce aggregation of C. elegans Orai1 (C.Orai1), and no CRAC current was detected in quiescent cells. However, upon store depletion, C.Orai1 and C.STIM1 functioned as a pair to locally sense the store depletion signal and to activate the CRAC channel. We substituted the N-terminus of H.STIM1 for the N-terminus of C.STIM1 (H-C.STIM1), which resulted in pre-puncta resting localization. In contrast, by replacing the C-terminus of C.STIM1 with that of H.STIM1, we made a chimeric protein (C.STIM1-H) that exhibited two distribution profiles at resting state, a diffuse ER pattern like H.STIM1, and large aggregates. Taken together, our results suggest that (1) despite highly conserved functional domains, C. elegans STIM1 and human STIM1 display different spatial distributions in HEK293 cells before store depletion; (2) the C.STIM1 puncta at peripheral sites are not sufficient for the aggregation and activation of C.Orai1 in the absence of store depletion; (3) the distinct distributions of C.STIM1 and H.STIM1 at resting state are determined by the cytoplasmic region of STIM1. (C) 2008 Elsevier Ltd. All rights reserved.