Fibroblast growth factor homologous factors modulate cardiac calcium channels.
Fibroblast growth factor homologous factors modulate cardiac calcium channels.
复制标题
DOI：
10.1161/circresaha.113.301215
复制
发表时间：
2013-08-02
影响因子：
20.1
通讯作者：
Pitt GS
中科院分区：
文献类型：
--
作者：
Hennessey JA;Wei EQ;Pitt GS
成纤维细胞生长因子（FGF）同源因子（FHFs，FGF 11 -14）是电压门控Na+通道的细胞内调节剂，但它们在心肌细胞中的分布表明它们具有其他功能。我们的目的是发现FHF在心肌细胞中的新作用，从蛋白质组学方法开始，以确定新的相互作用蛋白。从啮齿动物心室裂解物中亲和纯化FGF 13，然后进行质谱分析，揭示了与嗜连接蛋白-2的相互作用，嗜连接蛋白-2是一种组织L型Ca 2+通道CaV1.2和ryanodine受体RyR 2在二分体中紧密并列的蛋白质。免疫细胞化学分析显示，整体T-小管结构和本地化RyR 2不受FGF 13敲低在成年心室心肌细胞，但本地化的CaV1.2的影响。FGF 13敲低降低了CaV1.2电流密度，并且由于通道的异常定位而减少了表面处的CaV1.2的量。CaV1.2电流密度和通道定位通过表达shRNA不敏感的FGF 13来拯救，表明FGF 13的特定作用。与这些新发现的对CaV1.2的作用一致，我们证明了FGF 13也调节Ca 2+诱导的Ca 2+释放，这由FGF 13敲低后较小的Ca 2+瞬变所指示。此外，FGF 13敲低引起心脏动作电位半宽的显著降低。本研究表明，FHF不仅是电压门控Na+通道的有效调节剂，而且还影响Ca ~（2+）通道及其功能。我们预测FHF功能丧失突变会对Na+和Ca 2+通道电流产生不利影响，这表明FHF可能是致心律失常基因座，通过一种新的双离子通道机制导致心律失常。
Fibroblast growth factor (FGF) homologous factors (FHFs, FGF11-14) are intracellular modulators of voltage-gated Na+ channels, but their cellular distribution in cardiomyocytes indicated that they performed other functions. We aimed to uncover novel roles for FHFs in cardiomyocytes starting with a proteomic approach to identify novel interacting proteins. Affinity purification of FGF13 from rodent ventricular lysates followed by mass spectroscopy revealed an interaction with Junctophilin-2, a protein that organizes the close apposition of the L-type Ca2+ channel, CaV1.2, and the ryanodine receptor, RyR2, in the dyad. Immunocytochemical analysis revealed overall T-tubule structure and localization RyR2 were unaffected by FGF13 knockdown in adult ventricular cardiomyocytes, but localization of CaV1.2 was affected. FGF13 knockdown decreased CaV1.2 current density, and reduced the amount of CaV1.2 at the surface due to aberrant localization of the channels. CaV1.2 current density and channel localization were rescued by expression of an shRNA-insensitive FGF13, indicating a specific role for FGF13. Consistent with these newly discovered effects on CaV1.2, we demonstrated that FGF13 also regulated Ca2+-induced Ca2+ release, indicated by a smaller Ca2+ transient after FGF13 knockdown. Further, FGF13 knockdown caused a profound decrease in the cardiac action potential half width. This study demonstrates that FHFs are not only potent modulators voltage-gated Na+ channels, but also affect Ca2+ channels and their function. We predict that FHF loss-of-function mutations would adversely affect currents through both Na+ and Ca2+ channels, suggesting that FHFs may be arrhythmogenic loci, leading to arrhythmias through a novel, dual-ion channel mechanism.