Diminished Rbfox1 increases vascular constriction by dynamically regulating alternative splicing of CaV1.2 calcium channel in hypertension

Calcium influx from depolarized Ca(V)1.2 calcium channels triggers the contraction of vascular smooth muscle cells (VSMCs), which is important for maintaining vascular myogenic tone and blood pressure. The function of Ca(V)1.2 channel can be subtly modulated by alternative splicing (AS), and its aberrant splicing involves in the pathogenesis of multiple cardiovascular diseases. The RNA-binding protein Rbfox1 is reported to regulate the AS events of Ca(V)1.2 channel in the neuronal development, but its potential roles in vascular Ca(V)1.2 channels and vasoconstriction remain undefined. Here, we detect Rbfox1 is expressed in rat vascular smooth muscles. Moreover, the protein level of Rbfox1 is dramatically decreased in the hypertensive small arteries from spontaneously hypertensive rats in comparison with normotensive ones from Wistar-Kyoto rats. In VSMCs, Rbfox1 could dynamically regulate the AS of Ca(V)1.2 exons 9* and 33. By whole-cell patch clamp, we identify knockdown of Rbfox1 induces the hyperpolarization of Ca(V)1.2 current-voltage relationship curve in VSMCs. Furthermore, siRNA-mediated knockdown of Rbfox1 increases the K+-induced constriction of rat mesenteric arteries. In summary, our results indicate Rbfox1 modulates vascular constriction by dynamically regulating Ca(V)1.2 alternative exons 9* and 33. Therefore, our work elucidates the underlying mechanisms for Ca(V)1.2 channels regulation and provides a potential therapeutic target for hypertension.

Automated summary

This study found that Rbfox1 regulates vascular constriction by modulating the alternative splicing of Ca(V)1.2 channel exons 9* and 33. The protein level of Rbfox1 is significantly decreased in hypertensive rats, suggesting its involvement in the pathogenesis of cardiovascular diseases. This research reveals the underlying mechanisms for the regulation of Ca(V)1.2 channels and provides a potential therapeutic target for hypertension.