Interactome of splice variants of the ß2-subunit of L-type voltage-gated calcium channels in cardiac myocytes.

心肌细胞L型电压门控钙通道（LTCCs）钙内流的区室化对于心脏过程的正确调节是必要的。LTCC位于肌膜的不同亚细胞区室中。 空泡蛋白是LTCCs最重要的调节亚基。在四种Cavß2亚型中，Cavß2主要在心肌细胞中表达。我们最近的数据和以前的报告已经检测到不同的Cavß2剪接变体共存于成年小鼠和人类心肌细胞中。此外，该亚基与除LTCC之外的多种蛋白质的关联也已被报道。我们的初步结果表明，Cavß2的不同亚群位于小鼠心肌细胞中肌膜的不同亚细胞微区。这些不同的亚群可能对应于特定的剪接变异体参与招募独特的信号通路的成员到LTCCs附近。因此，该项目有两个主要目标。首先，我们将集中于与小鼠心肌细胞中表达的每个Cavß2剪接变体相互作用的蛋白质的鉴定。其次，我们将研究生理和心脏肥大条件下每个Cavß2剪接变体及其相关蛋白的细胞定位和蛋白表达。为了达到这些目标，我们将结合联合收割机串联亲和纯化，质谱，系统生物学分析和超分辨率显微镜。

The compartmentalization of calcium influxes through L-type voltage-gated calcium channels (LTCCs) in cardiomyocytes is necessary for the correct regulation of cardiac processes. LTCCs are located in different subcellular compartments in the sarcolemma. Cavß is the most important LTCCs regulatory subunit. Of the four Cavß isoforms, Cavß2 is predominantly expressed in cardiomyocytes. Our recent data and previous reports have detected different Cavß2 splice variants coexisting in adult mouse and human cardiomyocytes. In addition, the association of this subunit to diverse proteins besides the LTCCs has also been reported. Our preliminary results show that diverse subpopulations of Cavß2 are located in different subcellular microdomains of the sarcolemma in mouse cardiomyocytes. These different subpopulations could correspond to specific splice variants being involved in the recruitment of members of distinctive signaling pathways to LTCCs vicinity. Therefore, this project has two main goals. First, we will focus on the identification of proteins interacting with each Cavß2 splice variant expressed in mouse cardiomyocytes. Secondly, we will study the cellular localization and protein expression of each Cavß2 splice variant and their associated proteins under physiological and cardiac hypertrophy conditions. To reach these objectives we will combine tandem affinity purifications, mass spectrometry, systems biology analyses and super-resolution microscopy.