肠上皮细胞屏障稳态维持过程中PP1cδ与YAP的互作调控机理研究

Regenerative responses are particularly important in the mammalian gastrointestinal tract, a tissue subject to frequent erosion and renewal. Unrepaired mucosal injury disrupts the epithelial barrier that prevents translocation of intestinal microbiota, resulting in acute inflammation. Persistent failure to repair such damage can result in inflammatory bowel diseases (IBD). The regeneration and differentiation process of the small intestine is stringently regulated to ensure a balanced homeostasis. Our previously studies suggested the involvement of PP1cδ in epithelial cell barrier regulation. In IBD mouse models induced by TNF-α or DSS, the expression of PP1cδ increased significantly. In PP1cδ ΔIEC mouse models, severe IBD could be induced spontaneously, and the deficiency of PP1cδ was lethal. Simultaneously, reduction of YAP expression could be found in PP1cδ ΔIEC mouse. These results suggested that PP1cδ might regulate intestinal epithelial barrier regeneration interacted with YAP. The Molecular mechanism of PP1cδ regulated IEC and ISC function and regeneration mediated by YAP would be investigated in the study, to better understand the regular mechanism of IBD.

肠上皮细胞是保护机体的重要屏障，其自我更新维持了肠上皮屏障的完整性和稳态。上皮细胞受损会造成屏障功能紊乱，导致炎症性肠病（IBD）的发生。前期研究发现，肌球蛋白磷酸酶催化亚基PP1cδ在溃疡性结肠炎病人的肠上皮中表达下降；DSS诱导的肠炎模型小鼠，在其恢复阶段肠上皮PP1cδ表达明显增加，提示PP1cδ在上皮损伤后修复和IBD发生中可能起了重要作用。肠上皮细胞中特异性敲除PP1cδ的小鼠会自发严重的肠炎，屏障严重受损。体外培养敲除PP1cδ的肠类器官，其隐窝结构遭到破坏，上皮细胞坏死，与肠上皮存活和再生密切相关的YAP蛋白的表达显著下降。本课题将进一步阐述PP1cδ调控肠上皮细胞稳态和肠粘膜损伤后修复的分子机制，拟解决的科学问题为：1.PP1cδ如何调控肠上皮细胞稳态；2.PP1cδ是否通过YAP促进肠上皮屏障损伤后的再生和修复；3.PP1cδ及YAP是否与临床IBD的发病及病程相关。

肠上皮细胞是保护机体的重要屏障，其自我更新维持了肠上皮屏障的完整性和稳态。上皮细胞受损会造成屏障功能紊乱，导致炎症性肠病（IBD）的发生。前期研究发现，肌球蛋白磷酸酶催化亚基PP1cδ在溃疡性结肠炎病人的肠上皮中表达下降；DSS诱导的肠炎模型小鼠中，在其恢复阶段肠上皮PP1cδ表达明显增加，提示PP1cδ在上皮损伤后修复和IBD发生中可能起了重要作用。我们的研究发现，肠上皮细胞中特异性敲除PP1cδ的小鼠会自发严重的肠炎，屏障严重受损。PP1cδ表达量下调，对肠上皮细胞黏附、迁移及细胞周期产生不同程度的影响，从而影响其功能稳态。体外培养的类器官诱导敲除PP1cδ后，其隐窝结构遭到破坏，上皮细胞坏死，与肠上皮存活和再生密切相关的YAP蛋白的表达显著下降。在临床肠炎患者的样本中，检测了PP1cδ基因表达情况，发现其表达量低于正常组织，与小鼠模型结果相一致。本项目的研究有助于我们对PP1cδ影响肠上皮粘膜屏障损伤修复的作用机理进行阐述，试图为IBD的发病机理及临床治疗研究提供理论依据。