SIRT1在溃疡性结肠炎肠上皮细胞内质网应激损伤中的作用及机制研究

Recent researches have indicated that the excessive endoplasmic reticulum stress (ERS) would lead to abnormal apoptosis in intestinal epithelial cells, causing the dysfunction of intestinal barrier and intestinal inflammation. The function of silent mating type information regulation 2 homolog 1 (SIRT1), a histone acetylation enzyme which may play a vital role in the pathogensis of colitis as it ngatively regulatesthe apoptosis induced by ERS, remains unveiled in the course of ulcerative colitis (UC). Our previous findings have immunehistochemically demonstrated that the molecules corresponding to ERS (such as GRP78, caspase-12 and CHOP) were up-regulated in the mucosa from UC cases, whereas the expression level of SIRT1 was declined. In current study, both in vitro and in vivo experimental colitis models will be established to explore the regulatory impact of SIRT1 on inflammatory injuries within the intestinal epithelial cells and the effect of SIRT1 towards the apoptotic cell death by administration of selective inhibitor and agonist targeting SITR1, as well as small interfering RNA and recombinant adenovirus. The expression levels of ERS biomarker GRP78 and its downstream apoptosis-related molecules caspase-12 and CHOP will be detected to illuminate the regulatory role of SIRT1 in the apoptosis following ERS within the intestinal epithelial cells and the possible mechanisms underlying the effects of SIRT1.The results of this study will not only expand our understanding of the mechanisms involved in the pathogenesis and progression of UC, but also assist in the eventual development of new therapeutic targets for the disease.

近来研究发现过度内质网应激（ERS）诱发肠上皮细胞异常凋亡，导致肠黏膜屏障受损及肠道炎症。沉默信息调节因子1（SIRT1）可以减轻ERS诱导的细胞凋亡，可能是结肠炎的重要调控因子，但其在溃疡性结肠炎（UC）中的作用尚不明确。我们前期研究通过免疫组化发现ERS相关分子GRP78、caspase-12和CHOP在UC肠黏膜组织中表达增加，而SIRT1表达减少。本研究拟采用选择性SIRT1抑制剂或激动剂干预，RNA干扰和重组腺病毒等技术，通过体内外实验分别探讨SIRT1在UC肠上皮细胞炎症损伤中的作用，并进一步研究SIRT1表达改变对细胞凋亡的影响，同时检测ERS标记性分子GRP78及其诱导凋亡相关分子caspase-12、CHOP的表达水平，揭示SIRT1对于ERS诱导的肠上皮细胞凋亡的保护作用及可能机制。本课题的顺利实施，将为深入认识UC发生发展的分子机制，发现新的治疗靶标做出有益的尝试。

溃疡性结肠炎（ulcerative colitis, UC）是一种慢性非特异性肠道炎症性疾病。UC的病因和发病机制非常复杂，近来多种研究均表明肠上皮屏障损伤是UC的重要病因。过度内质网应激（endoplasmic reticulum stress，ERS）诱发肠上皮细胞异常凋亡，导致肠上皮屏障受损及肠道炎症。沉默信息调节因子1（Sirtuin 1，SIRT1）可以减轻ERS诱导的细胞凋亡，是结肠炎的重要调控因子，但其在UC中的作用尚不明确。本课题通过构建UC细胞及动物模型，探索SIRT1对结肠上皮炎症损伤的保护作用及机制。我们研究发现（1）SIRT1能够改善结肠炎症，通过调节紧密连接蛋白（occludin和ZO-1等）表达保护肠上皮屏障；（2）SIRT1通过减轻ERS诱导凋亡相关信号分子CHOP、caspase-12的表达，对结肠炎上皮细胞损伤具有保护作用;（3）并在此基础上，发现姜黄素能够减轻ERS，对结肠炎上皮损伤具有保护作用; (4) 白藜芦醇能够调节肠道上皮细胞自噬，改善肠道炎症。通过本课题的实施，深入研究了UC发生发展的分子机制，探索靶向SIRT1治疗在UC中的应用价值，最终为临床上UC患者的治疗药物开发提供理论依据。