PDF(Pubmed)
Abstract：
Earlier work has shown that ventricular ryanodine receptors (RyR2) within a cluster rearrange on phosphorylation as well as with a number of other stimuli. Using dSTORM, we investigated the effects of 300 nmol/liter isoproterenol on RyR2 clusters. In rat ventricular cardiomyocytes, there was a symmetrical enlargement of RyR2 cluster areas, a decrease in the edge-to-edge nearest neighbor distance, and distribution changes that suggested movement to increase the cluster areas by coalescence. The surface area covered by the phosphorylated clusters was significantly greater than in the control cells, as was the cluster density. This latter change was accompanied by a decreased cluster fragmentation, implying that new tetramers were brought into the sarcoplasmic reticulum. We propose a possible mechanism to explain these changes. We also visualized individual RyR2 tetramers and confirmed our earlier electron-tomographic finding that the tetramers are in a disorganized but non-random array occupying about half of the cluster area. Multiclusters, cluster groups defined by the maximum distance between their members, were analyzed for various distances. At 100 nm, the areas occupied by the multiclusters just exceeded those of the single clusters, and more than half of the multiclusters had only a single subcluster that could initiate a spark. Phosphorylation increased the size of the multiclusters, markedly so for distances >100 nm. There was no relationship between the number of subclusters in a group and the area covered by it. We conclude that isoproterenol induces rapid, significant, changes in the molecular architecture of excitation-contraction coupling.
摘要：
早期的工作表明，簇内的心室ryanodine受体（RyR2）在磷酸化以及许多其他刺激下重排。使用dSTORM，我们研究了300nmol/l异丙肾上腺素对RyR2簇的影响。在大鼠心室心肌细胞中，RyR2集群区域对称扩大，边缘到边缘最近邻距离的减小，和分布变化，建议通过合并来增加集群区域。磷酸化簇覆盖的表面积明显大于对照细胞，集群密度也是如此。后一种变化伴随着集群碎片减少，暗示新的四聚体被带入肌浆网。我们提出了一种可能的机制来解释这些变化。我们还可视化了单个RyR2四聚体，并证实了我们较早的电子层析成像发现，即四聚体呈无序但非随机的阵列，约占簇面积的一半。多集群，由成员之间的最大距离定义的群集组，对各种距离进行了分析。在100纳米，多集群占用的面积刚刚超过了单个集群的面积，超过一半的多集群只有一个子集群可以引发火花。磷酸化增加了多簇的大小，对于>100nm的距离明显如此。一个组中子簇的数量与其所覆盖的区域之间没有关系。我们得出结论，异丙肾上腺素诱导快速，重要的,激发-收缩耦合的分子结构变化。
