Functional communication between IP(3)R and STIM2 at subthreshold stimuli is a critical checkpoint for initiation of SOCE.
Functional communication between IP(3)R and STIM2 at subthreshold stimuli is a critical checkpoint for initiation of SOCE.
复制标题
阈下刺激下IP(3)R和STIM2之间的功能性通信是SOCE启动的关键检查点。
DOI：
10.1073/pnas.2114928118
复制
发表时间：
2022-01-18
影响因子：
11.1
通讯作者：
Ambudkar I
中科院分区：
文献类型：
--
作者：
Ahmad M;Ong HL;Saadi H;Son GY;Shokatian Z;Terry LE;Trebak M;Yule DI;Ambudkar I
STIM蛋白检测到[Ca 2 +]ER的减少，并聚集在内质网（ER）-质膜（PM）连接处，在那里它们募集并激活Orai 1。虽然STIM 1聚类需要大量的[Ca 2 +]ER减少，STIM 2显示preclustering在静息条件下，并调节基础Ca 2+进入。STIM 2的组成性聚集的潜在机制尚不清楚。我们在此表明，内源性STIM 2组装为移动的和非移动的集群和Orai 1被招募到后者。STIM 2簇的聚集由局部[Ca 2 +]ER的减少触发，所述局部[Ca 2 +]ER的减少由IP 3R的周围活性介导并由STIM 2 N末端感测。IP 3R和STIM 2之间的这种功能联系支配组成性STIM 2聚集，并确保在阈下刺激下[Ca 2 +]ER降低与Ca 2+进入激活的耦合。基质相互作用分子，STIM 1和STIM 2，在内质网（ER）[Ca 2 +]（[Ca 2 +]ER）中感知减少，并聚集在ER-质膜（ER-PM）连接处，在那里它们募集并激活Orai 1。当[Ca 2 +]ER相对较低时，STIM 1响应，而STIM 2在连接处显示组成性聚集，并被建议调节基础Ca 2+内流。在基础条件下确定STIM 2聚类的细胞线索尚不清楚。通过使用基因编辑来荧光标记内源性STIM 2，我们报告了内源性STIM 2组成性地定位在移动的和非移动的簇中。后者与ER-PM连接相关，并在基础条件下招募Orai 1。激动剂刺激增加不动的STIM 2簇，其协调Orai 1和STIM 1向连接处的募集。扩展的突触结合蛋白（E-Syt）2/3是形成ER-PM连接所必需的，但不足以形成STIM 2簇。重要的是，肌醇1，4，5-三磷酸受体（IP 3R）功能和局部[Ca 2 +]ER是固定STIM 2簇的主要驱动因素。在环境[IP 3]下增强或降低IP 3R功能会导致固定STIM 2簇的相应增加或衰减。我们发现，不动的STIM 2簇表示减少局部[Ca 2 +]ER介导的IP 3R，这是由STIM 2 N末端。最后，在基础条件下，细胞的周围PIP 2-PLC活性决定IP 3R功能、STIM 2的固定和基础Ca 2+进入，而激动剂刺激增强这些过程。总之，我们的研究结果表明，固定的STIM 2集群内ER-PM连接，ER-Ca 2+存储耗尽的第一个反应，是由IP 3R的并列促进，标志着一个检查点开始的Ca 2+进入。
STIM proteins sense decreases in [Ca2+]ER and cluster in endoplasmic reticulum (ER)–plasma membrane (PM) junctions where they recruit and activate Orai1. While STIM1 clustering requires substantial [Ca2+]ER decrease, STIM2 displays preclustering under resting conditions and regulates basal Ca2+ entry. The mechanism(s) underlying constitutive clustering of STIM2 is not known. We show herein that endogenous STIM2 assembles as mobile and immobile clusters and that Orai1 is recruited to the latter. Anchoring of STIM2 clusters is triggered by decreases in local [Ca2+]ER that are mediated by ambient activity of IP3R and sensed by the STIM2 N terminus. This functional link between IP3R and STIM2 governs constitutive STIM2 clustering and ensures coupling of [Ca2+]ER decrease at subthreshold stimuli with activation of Ca2+ entry. Stromal interaction molecules, STIM1 and STIM2, sense decreases in the endoplasmic reticulum (ER) [Ca2+] ([Ca2+]ER) and cluster in ER–plasma membrane (ER–PM) junctions where they recruit and activate Orai1. While STIM1 responds when [Ca2+]ER is relatively low, STIM2 displays constitutive clustering in the junctions and is suggested to regulate basal Ca2+ entry. The cellular cues that determine STIM2 clustering under basal conditions is not known. By using gene editing to fluorescently tag endogenous STIM2, we report that endogenous STIM2 is constitutively localized in mobile and immobile clusters. The latter associate with ER–PM junctions and recruit Orai1 under basal conditions. Agonist stimulation increases immobile STIM2 clusters, which coordinate recruitment of Orai1 and STIM1 to the junctions. Extended synaptotagmin (E-Syt)2/3 are required for forming the ER–PM junctions, but are not sufficient for STIM2 clustering. Importantly, inositol 1,4,5-triphosphate receptor (IP3R) function and local [Ca2+]ER are the main drivers of immobile STIM2 clusters. Enhancing, or decreasing, IP3R function at ambient [IP3] causes corresponding increase, or attenuation, of immobile STIM2 clusters. We show that immobile STIM2 clusters denote decreases in local [Ca2+]ER mediated by IP3R that is sensed by the STIM2 N terminus. Finally, under basal conditions, ambient PIP2-PLC activity of the cell determines IP3R function, immobilization of STIM2, and basal Ca2+ entry while agonist stimulation augments these processes. Together, our findings reveal that immobilization of STIM2 clusters within ER–PM junctions, a first response to ER-Ca2+ store depletion, is facilitated by the juxtaposition of IP3R and marks a checkpoint for initiation of Ca2+ entry.
登录
查看更多内容
影响因子：
16.6
作者：
Thillaiappan NB;Chavda AP;Tovey SC;Prole DL;Taylor CW
通讯作者：
Taylor CW
影响因子：
64.5
作者：
Giordano F;Saheki Y;Idevall-Hagren O;Colombo SF;Pirruccello M;Milosevic I;Gracheva EO;Bagriantsev SN;Borgese N;De Camilli P
通讯作者：
De Camilli P
影响因子：
8.8
作者：
Emrich SM;Yoast RE;Xin P;Arige V;Wagner LE;Hempel N;Gill DL;Sneyd J;Yule DI;Trebak M
通讯作者：
Trebak M
影响因子：
4.6
作者：
Sampieri A;Santoyo K;Asanov A;Vaca L
通讯作者：
Vaca L
影响因子：
64.8
作者：
Prakriya, Murali;Feske, Stefan;Hogan, Patrick G.
通讯作者：
Hogan, Patrick G.