Zhang Junting, Li Yiying, Chen Yujie, Yu Xiufeng, Wang Shanshan, Sun Hanliang, Zheng Xiaodong, Zhang Lixin, Wang Yifan, Zhu Daling
College of Pharmacy, Harbin Medical University, PR China; Central Laboratory of Harbin Medical University (Daqing), PR China.
College of Medical Laboratory Science and Technology, Harbin Medical University (Daqing), PR China; Central Laboratory of Harbin Medical University (Daqing), PR China.
J Mol Cell Cardiol. 2023 Mar;176:41-54. doi: 10.1016/j.yjmcc.2023.01.009. Epub 2023 Jan 27.
Pulmonary hypertension (PH) is a serious and fatal disease characterized by pulmonary vasoconstriction and pulmonary vascular remodeling. The excessive autophagy of pulmonary artery smooth muscle cells (PASMCs) is one of the important factors of pulmonary vascular remodeling. A number of studies have shown that circular RNA (circRNA) can participate in the onset of PH. Our previous studies have shown that circRNA calmodulin 4 (circ-calm4) is involved in the progression of hypoxic PH. However, the role of circ-calm4 on regulation of hypoxic PH autophagy has not been reported. In this study, we demonstrated for the first time that hypoxia-mediated upregulated circ-calm4 expression has a key regulatory effect on autophagy in hypoxia-induced PASMCs and hypoxic PH mouse models. Knockdown of circ-calm4 both in vivo and in vitro can inhibit the autophagy in PASMCs induced by hypoxia. We also performed bioinformatics predictions and conducted experiments to verify that circ-calm4 bound to the purine-rich binding protein (Purb) to promote its expression in the nucleus, thereby initiating the transcription of autophagy-related protein Beclin1. Interestingly, we found that Beclin1 transcription initiated by Purb was accompanied by a modification of Beclin1 super-enhancer to improve transcription activity and efficiency. Overall, our results confirm that the circ-calm4/Purb/Beclin1 signal axis is involved in the occurrence of hypoxia-induced PASMCs autophagy, and the novel regulatory mechanisms and signals transduction pathways in PASMC autophagy induced by hypoxia.
肺动脉高压（PH）是一种严重的致命疾病，其特征为肺血管收缩和肺血管重塑。肺动脉平滑肌细胞（PASMCs）的过度自噬是肺血管重塑的重要因素之一。多项研究表明，环状RNA（circRNA）可参与PH的发病过程。我们之前的研究表明，circRNA钙调蛋白4（circ-calm4）参与低氧性PH的进展。然而，circ-calm4在低氧性PH自噬调节中的作用尚未见报道。在本研究中，我们首次证明低氧介导的circ-calm4表达上调对低氧诱导的PASMCs和低氧性PH小鼠模型中的自噬具有关键调节作用。体内和体外敲低circ-calm4均可抑制低氧诱导的PASMCs自噬。我们还进行了生物信息学预测并开展实验验证circ-calm4与富含嘌呤结合蛋白（Purb）结合以促进其在细胞核中的表达，从而启动自噬相关蛋白Beclin1的转录。有趣的是，我们发现由Purb启动的Beclin1转录伴随着Beclin1超级增强子的修饰，以提高转录活性和效率。总体而言，我们的结果证实circ-calm4/Purb/Beclin1信号轴参与低氧诱导的PASMCs自噬的发生，以及低氧诱导的PASMC自噬中的新调节机制和信号转导途径。
