Aberrant Splicing Induced by Dysregulated Rbfox2 Produces Enhanced Function of CaV1.2 Calcium Channel and Vascular Myogenic Tone in Hypertension
Aberrant Splicing Induced by Dysregulated Rbfox2 Produces Enhanced Function of CaV1.2 Calcium Channel and Vascular Myogenic Tone in Hypertension
复制标题
Rbfox2 失调诱导的异常剪接增强了高血压中 CaV1.2 钙通道和血管肌源性张力的功能。
DOI：
10.1161/hypertensionaha.117.09301
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发表时间：
2017-12-01
期刊：
影响因子：
8.3
通讯作者：
Wang, Juejin
中科院分区：
文献类型：
--
作者：
Zhou, Yingying;Fan, Jia;Wang, Juejin
血管平滑肌细胞中激活的电压门控性钙通道Ca（V）1.2的钙内流对于维持肌源性张力和血压是必不可少的。选择性剪接是一种转录后修饰机制，可优化Ca（V）1.2通道的功能。已知剪接因子Rbfox2在神经元发育期间调节Ca（V）1.2前mRNA选择性剪接事件。然而，Rbfox2在调节血管Ca（V）1.2通道的关键功能和高血压发病机制中的作用仍然是未知的。在这里，我们报告的Ca（V）1.2通道的比例增加了10.3%，而与选择性外显子33的高血压动脉减少了10.5%。令人惊讶的是，Rbfox2的表达水平增加了约3倍，可能是因为Rbfox2的显性负性同种型的上调。在血管平滑肌细胞中，我们发现Rbfox2的敲低动态地增加了选择性外显子9*，而减少了Ca（V）1.2通道的外显子33包含。通过膜片钳技术，我们发现Rbfox2诱导的选择性剪接减弱使血管Ca（V）1.2钙通道的稳态激活和失活曲线向超极化方向移动，使窗口电流电位向负方向移动。此外，siRNA介导的Rbfox2敲低增加了压力诱导的大鼠肠系膜动脉血管肌源性张力。综上所述，我们的数据表明，Rbfox2通过动态调节交替外显子9* 和33的表达来调节血管Ca（V）1.2钙通道的功能，从而影响血管肌源性张力。因此，我们的工作表明Rbfox2在高血压中的关键作用，这为设计抗高血压治疗提供了合理的依据。
Calcium influx from activated voltage-gated calcium channel Ca(V)1.2 in vascular smooth muscle cells is indispensable for maintaining myogenic tone and blood pressure. The function of Ca(V)1.2 channel can be optimized by alternative splicing, one of post-transcriptional modification mechanisms. The splicing factor Rbfox2 is known to regulate the Ca(V)1.2 pre-mRNA alternative splicing events during neuronal development. However, Rbfox2's roles in modulating the key function of vascular Ca(V)1.2 channel and in the pathogenesis of hypertension remain elusive. Here, we report that the proportion of Ca(V)1.2 channels with alternative exon 9* is increased by 10.3%, whereas that with alternative exon 33 is decreased by 10.5% in hypertensive arteries. Surprisingly, the expression level of Rbfox2 is increased approximate to 3-folds, presumably because of the upregulation of a dominant-negative isoform of Rbfox2. In vascular smooth muscle cells, we find that knockdown of Rbfox2 dynamically increases alternative exon 9*, whereas decreases exon 33 inclusion of Ca(V)1.2 channels. By patch-clamp studies, we show that diminished Rbfox2-induced alternative splicing shifts the steady-state activation and inactivation curves of vascular Ca(V)1.2 calcium channel to hyperpolarization, which makes the window current potential to more negative. Moreover, siRNA-mediated knockdown of Rbfox2 increases the pressure-induced vascular myogenic tone of rat mesenteric artery. Taken together, our data indicate that Rbfox2 modulates the functions of vascular Ca(V)1.2 calcium channel by dynamically regulating the expressions of alternative exons 9* and 33, which in turn affects the vascular myogenic tone. Therefore, our work suggests a key role for Rbfox2 in hypertension, which provides a rational basis for designing antihypertensive therapies.