胰蛋白酶/PAR2激活YAP参与组织再生及炎症相关结肠癌的发生

The precise control of organ size is crucial during animal development and regeneration. Chronic inflammation is a process of repeated damage and repair and overgrowth of organ or tissue results in tumour. However the mechanisms by which control the regeneration is largely unknown. As the key molecule of Hippo pathway, YAP involves in the biology of stem cell and plays important roles in the homeostasis, regeneration and tumorigenesis of gut. Interestingly, the mutation or amplification of YAP gene is not common in solid tumors. Therefore it is important to find the mechanisms by which YAP was activated by microenvironment signaling. Our preliminary study indicated that serine proteinases through the activation of proteinase activated receptor 2 (PAR2) enhanced YAP activity and maintained the stemness of colon cells. The current project aim to study 1) whether serine proteinases through PAR2 mediate regeneration and inflammation-related tumorigenesis in colon; 2) the mechanisms by which PAR2 activates YAP and maintain the stemness of colon cells; 3) the potential of PAR2 signaling as a target to prevent colitis-related colon cancer.

精确地控制再生过程是防止慢性炎症相关肿瘤发生的重要机制。作为Hippo通路的核心分子，YAP是目前已知最重要的与器官大小相关的分子，而且在干细胞、肠道稳态、修复再生和肿瘤发生中都发挥重要作用。有趣的是，Hippo/YAP通路自身突变并不常见，所以明确导致YAP活化的上游信号就显得尤为重要（Cell，2015， 163：811-828）。我们的研究强烈提示：结肠组织中胰蛋白酶可能通过其下游受体PAR2(proteinase activated receptor 2)，激活YAP参与干细胞的维持及结肠炎相关结肠癌的发生。本项目拟研究：胰蛋白酶是否通过PAR2信号通路参与结肠粘膜的损伤后的再生过程以及炎症相关结肠癌的发生；PAR2 活化YAP维持细胞干性的分子机制；靶向胰蛋白酶/PAR2干预慢性结肠炎相关结肠癌发生的可能性。该项目将为寻找新的预防和干预慢性疾病相关结直肠癌的新靶点提供理论基础。

炎症与肿瘤的发生发展密切相关，慢性炎症疾病可以显著提高肿瘤的发生率。慢性炎症是一个反复损伤、反复修复的过程，精确地控制再生过程是防止慢性炎症相关肿瘤发生的重要机制。作为Hippo通路的核心分子，YAP是目前已知最重要的与器官大小相关的分子，而且在干细胞、肠道稳态、修复再生和肿瘤发生中都发挥重要作用。本项研究的目的是：明确胰蛋白酶是否通过PAR2信号通路参与结肠粘膜的损伤后的再生；PAR2 活化YAP维持细胞干性的分子机制；靶向胰蛋白酶/PAR2干预慢性结肠炎相关结肠癌发生的可能性。首先，我们通过基因敲除物实验证实了PAR2参与炎症损伤后的修复再生。敲除PAR2后显著抑制了肠道修复，延缓了隐窝组织再生的速度。其次，在分子机制方面，抑制PAR2信号通路显著降低YAP的蛋白水平。进一步的研究发现PAR2调控YAP蛋白和磷酸酶PP1结合促进其去磷酸化作用，进而增强其蛋白的稳定性。最后在细胞功能学方面，干扰PAR2抑制细胞克隆形成，增加细胞内ROS的产生及NO诱导的细胞凋亡，但是过表达YAP则可以有效逆转这些现象。综上所述，在本项目的资助下我们首次明确了PAR2信号通路在肠道修复过程中的作用及分子机制。.关键词：结直肠癌;蛋白酶活化受体2；损伤修复；YAP