PDF(Pubmed)
Abstract：
Coordinated events of calcium (Ca2+) released from the endoplasmic reticulum (ER) are key second messengers in excitable cells. In pain-sensing dorsal root ganglion (DRG) neurons, these events can be observed as Ca2+ sparks, produced by a combination of ryanodine receptors (RyR) and inositol 1,4,5-triphosphate receptors (IP3R1). These microscopic signals offer the neuronal cells with a possible means of modulating the subplasmalemmal Ca2+ handling, initiating vesicular exocytosis. With super-resolution dSTORM and expansion microscopies, we visualised the nanoscale distributions of both RyR and IP3R1 that featured loosely organised clusters in the subplasmalemmal regions of cultured rat DRG somata. We adapted a novel correlative microscopy protocol to examine the nanoscale patterns of RyR and IP3R1 in the locality of each Ca2+ spark. We found that most subplasmalemmal sparks correlated with relatively small groups of RyR whilst larger sparks were often associated with larger groups of IP3R1. These data also showed spontaneous Ca2+ sparks in <30% of the subplasmalemmal cell area but consisted of both these channel species at a 3.8-5 times higher density than in nonactive regions of the cell. Taken together, these observations reveal distinct patterns and length scales of RyR and IP3R1 co-clustering at contact sites between the ER and the surface plasmalemma that encode the positions and the quantity of Ca2+ released at each Ca2+ spark.
摘要：
从内质网（ER）释放的钙（Ca2）的协调事件是可兴奋细胞中的关键第二信使。在痛觉背根神经节（DRG）神经元中，这些事件可以观察到Ca2+火花，由ryanodine受体（RyR）和肌醇1,4,5-三磷酸受体（IP3R1）的组合产生。这些微观信号为神经元细胞提供了调节亚浆膜Ca2+处理的可能手段，启动囊泡胞吐。使用超分辨率dSTORM和扩展显微镜，我们观察了RyR和IP3R1的纳米级分布，它们在培养的大鼠DRG躯体的质膜下区域具有松散组织的簇。我们采用了一种新颖的相关显微镜协议，以检查每个Ca2火花局部的RyR和IP3R1的纳米级图案。我们发现，大多数浆膜下火花与相对较小的RyR组相关，而较大的火花通常与较大的IP3R1组相关。这些数据还显示，在<30％的质膜下细胞区域中自发的Ca2火花，但由这两种通道物种组成，密度比细胞非活动区域高3.8-5倍。一起来看,这些观察结果揭示了RyR和IP3R1在ER和表面质膜之间的接触位点共同聚集的不同模式和长度尺度，这些位置和数量编码在每个Ca2火花处释放的Ca2。
