肌球蛋白磷酸酶依赖的肠上皮细胞程序性坏死调节机制

Intestinal epithelial cells form a mechanical barrier to prevent the entry of harmful bacteria and toxin from outside of the body. The renewal of epithelial cells keeps the intact of such a barrier function. Intestinal inflammatory bowel disease is closed associated with epithelial cell necroptosis. However, the function of protein phosphatase in regulation of necroposis is completely unknown. Our preliminary data have showed that intestinal epithelial specific knockout of the myosin phosphatase target subunit-1 (MYPT1) caused epithelial cell necroptosis in mice and this process can be blocked by a specific necroptosis inhibitor necrostain-1. In this study, we will further investigate the molecular mechanisms by which MYPT1 regulating necroptosis. We will further: (1) confirm the necroptosis phenotype triggered by MYPT1 deletion by knockdown RIP3 expression in cultured eneroids and by crossing MYPT1fl/fl/Villin-CreERT2 with RIP3-/- mice; (2) use biochemical and molecular methods to find out the substrate(s) of MYPT1 in necroptosis signaling pathway; (3) explore the mechanisms by which MYPT1 was down-regulated in mouse model of inflammatory bowel disease and the potential relationship between MYPT1 down-regulation and disease development. Our study will definitely help us to understand the molecular mechanisms of necroptosis mediated by MYPT1 and ultimately, lead to significant advances in inflammatory bowel disease therapy.

肠黏膜上皮细胞是机体抵御致病微生物和毒素侵入的一道机械屏障。肠上皮细胞的更新维持了上皮屏障的完整性，炎症性肠病的发生和肠上皮细胞的程序性坏死密切相关。目前对蛋白磷酸酶调节细胞程序性坏死的机制完全不清楚。前期研究发现，特异性敲除肌球蛋白磷酸酶的调节亚基MYPT1的肠上皮细胞发生程序性坏死，并可被necrostatin-1所抑制。本研究将进一步探讨MYPT1调节程序性坏死的分子机制，研究内容包括:(1)通过干扰enteroids中RIP3表达，以及MYPT1、RIP3双敲小鼠，进一步确定MYPT1缺失导致了程序性坏死的发生；(2)运用生化和分子的方法，确定MYPT1的靶向底物及具体作用方式；(3)探索MYPT1在炎症性肠病中表达下降的原因及其和疾病发生之间的联系。本项目的研究有助于我们深入了解MYPT1调节程序性坏死的分子机制，也为炎症性肠病治疗药物的研发提供借鉴。

肠黏膜上皮细胞是机体抵御致病微生物和毒素侵入的一道机械屏障。肠上皮细胞的更新维持了上皮屏障的完整性，炎症性肠病的发生和肠上皮细胞的程序性坏死密切相关。目前对蛋白磷酸酶调节细胞程序性坏死的机制还不清楚。本项目研究了MYPT1调控内脏内胚层和肠上皮细胞程序性坏死的机制。我们研究发现，（1）内脏内胚层和肠上皮细胞中，MYPT1主要表达在细胞-细胞连接处；（2）MYPT1缺失的内脏内胚层细胞发生了细胞坏死；（3） 培养MYPT1flox/flox的MEF细胞，并在体外感染Cre病毒，可引起MEF细胞坏死；(4) 在L929细胞中敲低MYPT1，细胞坏死增加，并且这种MYPT1敲低引起的细胞坏死可被程序性坏死特异性抑制剂necrostatin-1所抑制；（5）特异性敲除MYPT1的肠上皮细胞发生自发的程序性坏死，并可被necrostatin-1所抑制。本项目的研究有助于我们深入了解MYPT1调节程序性坏死的分子机制，也为炎症性肠病治疗药物的研发提供借鉴。