Key Laboratory of Targeted Invention of Cardiovascular Disease and Collaborative Innovation Center for Cardiovascular Translational Medicine,, Department of Pathophysiology, Nanjing Medical University, Nanjing, China.
Department of Pathophysiology, Wuxi College of Medicine, Jiangnan University, Jiangsu, China.
J Cell Biochem. 2018 Apr;119(4):3384-3393. doi: 10.1002/jcb.26505. Epub 2018 Jan 4.
Endothelial-to-mesenchymal transition (EndMT) contributes to the pathogenesis of a host of human diseases. RhoJ, a small G protein, is abundantly expressed in endothelial cells. In the present study, we investigated the potential role RhoJ plays in EndMT. We report that RhoJ depletion by small interfering RNA attenuated hypoxia induced EndMT in both immortalized endothelial cells and human primary microvascular endothelial cells. RhoJ knockdown blocked the recruitment of TWIST and SNAIL, two transcriptional repressors, to the promoter region of VE-CADHERIN, a prominent endothelial marker. RhoJ mediated the induction of TWIST and SNAIL expression, under hypoxic conditions, by promoting the binding of HIF-1α to the gene promoters and by enhancing the accumulation of trimethylated histone H3K4. Further analysis revealed that RhoJ was essential for the up-regulation of WDR5, a key component of the mammalian H3K4 methyltransferase, by hypoxia thereby leading to the trans-activation of TWIST and SNAIL. Finally, lentivirus mediated over-expression of WDR5 compensated for the loss of TWIST and SNAIL and allowed EndMT to proceed despite the absence of RhoJ in hypoxia-challenged endothelial cells. In conclusion, we propose that RhoJ-dependent induction of WDR5 may be essential for hypoxia-induced EndMT.
内皮-间质转化（EndMT）参与了多种人类疾病的发病机制。RhoJ 是一种小 G 蛋白，在血管内皮细胞中大量表达。在本研究中，我们研究了 RhoJ 在 EndMT 中的潜在作用。我们报告称，通过小干扰 RNA 敲低 RhoJ 可减弱缺氧诱导的永生性内皮细胞和人原代微血管内皮细胞中的 EndMT。RhoJ 敲低阻止了 TWIST 和 SNAIL（两种转录抑制因子）招募到 VE-CADHERIN（一种突出的内皮标志物）的启动子区域。在缺氧条件下，RhoJ 通过促进 HIF-1α 与基因启动子结合并增强三甲基化组蛋白 H3K4 的积累，介导 TWIST 和 SNAIL 表达的诱导。进一步分析表明，RhoJ 对于 WDR5（哺乳动物 H3K4 甲基转移酶的关键组成部分）的上调是必需的，WDR5 的上调导致 TWIST 和 SNAIL 的反式激活。最后，慢病毒介导的 WDR5 过表达补偿了 TWIST 和 SNAIL 的缺失，并允许内皮细胞在缺氧挑战下进行 EndMT，尽管缺乏 RhoJ。总之，我们提出 RhoJ 依赖性诱导的 WDR5 可能是缺氧诱导的 EndMT 所必需的。
