Piezo1介导的力学生物学机制调控EMT参与肠纤维化

Intestinal fibrosis is an important pathological change in the chronic course of IBD. At present, there is a lack of effective interventions. Our previous studies have confirmed that changes in the mechanical microenvironment can directly promote fibrosis progress, but the mechanism is still unclear. Piezo1 is a mechanically gated ion channel. We found that Piezo1 wass expressed in intestinal epithelial cells and was an important "sensor" in the mechanical microenvironment of intestinal epithelial cells. After intervention with Piezo1 blocker, the degree of intestinal fibrosis was reduced. Therefore, we speculate that Piezo1 plays an important role in the progression of intestinal fibrosis. Previous studies have shown that mechanical stimulation can induce EMT in epithelial cells, which plays a key role in the progression of intestinal fibrosis. After Piezo1 blocker was given, EMT was significantly inhibited. Therefore, the mechano-biological mechanism of "mechanical signal - Piezo1 - EMT" is likely to play an important role. This topic focuses on whether "mechanical signal-Piezo1" is the key of EMT and its regulation mechanism. We will perform scientific experiments, under the condition of different mechanical signals, by intervention of Piezo1 and downstream key signaling pathways Integrin-FAK, RhoA/ROCK-MLCK-Actin to prove the function and mechanism of EMT. This study will provide a new therapeutic target for IBD intestinal fibrosis.

肠纤维化是IBD慢性病程中重要病理改变，目前缺少有效干预措施。我们前期研究证实，机械微环境的改变可直接促进纤维化进展，但机制尚不清楚。Piezo1是机械门控离子通道，我们发现Piezo1在肠上皮细胞中表达，是肠上皮细胞机械微环境的重要“感受器”，Piezo1阻断剂干预后，肠纤维化程度减轻。因此，我们推测Piezo1在肠纤维化进展中起重要作用。我们前期研究发现力学刺激可以导致上皮细胞EMT，给与Piezo1阻断剂后，EMT则被显著抑制，而EMT在肠纤维化进展中作用关键。可见，“机械信号—Piezo1—EMT”这一力学生物学机制很可能举足轻重。本课题重点探讨“机械信号-Piezo1”是否是EMT的关键及其调控机制，我们将在不同机械信号的刺激下，干预Piezo1以及下游关键信号通路Integrin-FAK、RhoA/ROCK-MLCK-Actin，进一步阐明肠纤维化的机制，为其治疗提供新的靶点。

肠纤维化是IBD慢性病程中重要病理改变，目前缺少有效干预措施。Piezo1是机械门控离子通道，我们发现Piezo1在肠上皮细胞中表达，是肠上皮细胞机械微环境的重要“感受器”。. 我们通过构建肠道上皮细胞特异性piezo1敲除（villin-Cre, piezo1-flox）动物，采用通用的DSS模型构慢性肠道炎症动物模型，验证了piezo1蛋白在慢性肠道炎症的环境下对于肠道纤维化的影响。证明了piezo1蛋白的敲除对于肠道慢性炎症的影响有限，略微增加了慢性炎症的强度，但是piezo1的敲除却显著降低了肠道的纤维化程度。我们进一步验证了之前的假设: piezo1蛋白的存在会加强上皮细胞的上皮间质转化（EMT）过程，增强了纤维化过程中的成纤维细胞数量，从而加强了慢性炎症环境当中的肠道纤维化程度。同时piezo1蛋白的敲除不会影响肠道主要的炎症因子水平，也不能影响成纤维细胞的活化水平。EMT产生的新的成纤维细胞大多数处于非活化状态，piezo1的敲除与否并不改变成纤维细胞的炎症微环境，也不改变成纤维细胞的活化，因此主要分泌I型胶原蛋白和纤连蛋白的活化成纤维细胞数量差异不显著。但是成纤维细胞的增多还是增加了肠道内基质蛋白的累积。. 我们进一步探究了Piezo1导致EMT过程的加强机制，发现可能的机制是：①piezo1会加强钙离子的内流引起线粒体内钙离子的波动，干扰了线粒体的氧化磷酸化和能量代谢过程，是的ATP生成减少而ROS累积从而导致EMT过程；②piezo1加强了TGF-β下游的信号通路，进而加强炎症环境下上皮细胞的EMT过程。后续我们将继续深入探究基质硬度对于piezo1蛋白功能的调控。. 本研究对于防治肠道纤维化具有重要意义：①证明了piezo1蛋白是肠道纤维化的重要靶点，干预piezo1会减轻肠道纤维化；②找到了piezo1蛋白对于细胞EMT过程的影响机制。