Junctophilin-4 facilitates inflammatory signalling at plasma membrane-endoplasmic reticulum junctions in sensory neurons
Junctophilin-4 facilitates inflammatory signalling at plasma membrane-endoplasmic reticulum junctions in sensory neurons
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DOI：
10.1113/jp281331
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发表时间：
2021-03-03
影响因子：
5.5
通讯作者：
Gamper, Nikita
中科院分区：
文献类型：
--
作者：
Hogea, Alexandra;Shah, Shihab;Gamper, Nikita
大鼠体感觉神经元表达一种连接蛋白——结蛋白-4 （junctophilin-4, JPH4）。JPH4是在这些神经元的质膜和内质网交界处形成储存Ca2+进入复合物所必需的。JPH4的下调会损害内质网Ca2+储存的再填充和感觉神经元的连接Ca2+信号传导。在体内敲除大鼠背根神经节感觉神经元中的JPH4可显著减轻实验性炎症性疼痛。JPH4维持的连接纳米结构域Ca2+信号是炎症性疼痛机制的重要贡献者。真核细胞内质网和质膜的连接（ER-PM连接）形成信号纳米结构域。ER-PM连接存在于外周感觉神经元中，对G蛋白偶联受体（GPCR）信号的保真度很重要。然而，对于这些连接在体感觉转导中的组装、维持和生理作用知之甚少。利用荧光成像、近距离结联、超分辨率显微镜、体外和体内基因敲除，我们证明了结膜亲蛋白家族的成员结膜亲蛋白4 （JPH4）对于大鼠体感觉神经元ER-PM连接处储存Ca2+进入（SOCE）复合物的形成是必要的。因此，我们发现JPH4定位于ER- pm连接区域，并在ER Ca2+储存耗尽时与SOCE蛋白STIM1和Orai1共同聚集。JPH4的下调会损害感觉神经元中SOCE和ER Ca2+储存的重新填充。此外，我们证明了JPH4和连接纳米结构域Ca2+信号在炎症介质缓激素诱导的疼痛样反应中的关键作用。事实上，在大鼠体内，后爪注射缓激肽诱导的背根神经节（DRG）感觉神经元中JPH4的敲低显著缩短了攻击性行为的持续时间。由于内质网为多种炎症介质的兴奋作用提供Ca2+，我们认为JPH4维持的连接纳米结构域Ca2+信号是炎症性疼痛机制的重要因素。
Key pointsRat somatosensory neurons express a junctional protein, junctophilin-4 (JPH4)JPH4 is necessary for the formation of store operated Ca2+ entry (SOCE) complex at the junctions between plasma membrane and endoplasmic reticulum in these neurons.Knockdown of JPH4 impairs endoplasmic reticulum Ca2+ store refill and junctional Ca2+ signalling in sensory neurons.In vivo knockdown of JPH4 in the dorsal root ganglion (DRG) sensory neurons significantly attenuated experimentally induced inflammatory pain in rats.Junctional nanodomain Ca2+ signalling maintained by JPH4 is an important contributor to the inflammatory pain mechanisms.Junctions of endoplasmic reticulum and plasma membrane (ER-PM junctions) form signalling nanodomains in eukaryotic cells. ER-PM junctions are present in peripheral sensory neurons and are important for the fidelity of G protein coupled receptor (GPCR) signalling. Yet little is known about the assembly, maintenance and physiological role of these junctions in somatosensory transduction. Using fluorescence imaging, proximity ligation, super-resolution microscopy, in vitro and in vivo gene knockdown we demonstrate that a member of the junctophilin protein family, junctophilin-4 (JPH4), is necessary for the formation of store operated Ca2+ entry (SOCE) complex at the ER-PM junctions in rat somatosensory neurons. Thus we show that JPH4 localises to the ER-PM junctional areas and co-clusters with SOCE proteins STIM1 and Orai1 upon ER Ca2+ store depletion. Knockdown of JPH4 impairs SOCE and ER Ca2+ store refill in sensory neurons. Furthermore, we demonstrate a key role of the JPH4 and junctional nanodomain Ca2+ signalling in the pain-like response induced by the inflammatory mediator bradykinin. Indeed, an in vivo knockdown of JPH4 in the dorsal root ganglion (DRG) sensory neurons significantly shortened the duration of nocifensive behaviour induced by hindpaw injection of bradykinin in rats. Since the ER supplies Ca2+ for the excitatory action of multiple inflammatory mediators, we suggest that junctional nanodomain Ca2+ signalling maintained by JPH4 is an important contributor to the inflammatory pain mechanisms.