JPH-2 interacts with Cai-handling proteins and ion channels in dyads: Contribution to premature ventricular contraction-induced cardiomyopathy.
JPH-2 interacts with Cai-handling proteins and ion channels in dyads: Contribution to premature ventricular contraction-induced cardiomyopathy.
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DOI：
10.1016/j.hrthm.2015.10.037
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发表时间：
2016-03
期刊：
影响因子：
5.5
通讯作者：
Tseng GN
中科院分区：
文献类型：
--
作者：
Jiang M;Zhang M;Howren M;Wang Y;Tan A;Balijepalli RC;Huizar JF;Tseng GN
在室性早搏诱导的心肌病（PVC-CM）的犬模型中，Cav1.2下调并从t-小管错位。Junctophilin-2（JPH-2）也被下调。了解JPH-2在PVC-CM中的作用，并探讨参与二联体结构和功能的其他蛋白质的变化。我们定量t-小管内容物（活肌细胞中的二-8-ANEPPS荧光），检查肌细胞超微结构（电子显微镜），探测JPH-2相互作用蛋白（免疫共沉淀），定量二联体和非二联体蛋白水平（免疫印迹），并检查二联体蛋白的亚细胞分布（免疫荧光/共聚焦显微镜）。我们还测试了使用异源表达的通道功能的直接JPH-2调节（相对于通过二分体形成的间接调节）。PVC心肌细胞的t-小管含量减少，但其他超微结构正常。在检测的19种蛋白质中，只有JPH-2、桥接整合子-1（BIN-1）和Cav1.2在PVC心脏中高度下调。然而，统计分析表明，当JPH-2下调时，二分体蛋白水平普遍降低。此外，在PVC心肌细胞中，包括Na/Ca交换器在内的几种二分体蛋白缺失或从二分体转移到外周表面。JPH-2直接或间接与Cai处理蛋白Cav1.2和KCNQ 1相互作用，但不与BIN-1或其他测试的支架蛋白相互作用。在没有二联体的哺乳动物细胞中的表达证实了JPH-2对ICaL（Cav1.2/Cavβ2）和IKs（KCNQ 1/KCNE 1）的直接调节。JPH-2不仅仅是一种“二分体胶”：它可以调节二分体区域中的CaI处理和离子通道功能。JPH-2、BIN-1和Cav1.2的下调在PVC-CM中起决定性作用。剖析三者之间的层次关系对于设计预防PVC-CM进展的治疗干预措施是必要的。
In a canine model of premature ventricular contraction-induced cardiomyopathy (PVC-CM), Cav1.2 is downregulated and misplaced from t-tubules. Junctophilin-2 (JPH-2) is also downregulated. To understand the role of JPH-2 in PVC-CM, and to probe changes in other proteins involved in dyad structure and function. We quantify t-tubule contents (di-8-ANEPPS fluorescence in live myocytes), examine myocyte ultra-structures (electron microscopy), probe JPH-2 interacting proteins (co-immunoprecipitation), quantify dyad and non-dyad protein levels (immunoblotting), and examine subcellular distributions of dyad proteins (immunofluorescence/confocal microscopy). We also test direct JPH-2 modulation of channel function (vs indirect modulation through dyad formation) using heterologous expression. PVC myocytes have reduced t-tubule contents but otherwise normal ultra-structures. Among nineteen proteins examined, only JPH-2, bridging-integrator-1 (BIN-1) and Cav1.2 are highly downregulated in PVC hearts. However, statistical analysis indicates a general reduction of dyad protein levels when JPH-2 is downregulated. Furthermore, several dyad proteins, including Na/Ca exchanger, are missing or shifted from dyads to peripheral surface in PVC myocytes. JPH-2 directly or indirectly interacts with Cai-handling proteins, Cav1.2 and KCNQ1, although not BIN-1 or other scaffolding proteins tested. Expression in mammalian cells, that do not have dyads, confirms direct JPH-2 modulation of ICaL (Cav1.2/Cavβ2) and IKs (KCNQ1/KCNE1). JPH-2 is more than a ‘dyad glue’: it can modulate Cai-handling and ion channel function in the dyad region. Downregulation of JPH-2, BIN-1 and Cav1.2 plays a deterministic role in PVC-CM. Dissecting the hierarchical relationship among the three is necessary for the design of therapeutic interventions to prevent the progression of PVC-CM.