ZIP7调控Shank3/PKCɛ通路对炎症性肠病黏膜屏障的影响及机制研究

Intestinal barrier destruction plays a key role in the progress of inflammatory bowel disease (IBD), and zinc homeostasis disorder leads to barrier destruction. Our previous studies found that the expression of zinc transporter protein 7 (ZIP7) revealed inflammation-related downregulation in IBD intestinal mucosa, while upregulation the expression of ZIP7 could restore mucosal barrier integrity and relieve intestinal inflammation, which was not reported before. ZIP7 is a unique intracellular free zinc transporter protein, and its downregulation leads to the decrease of cytoplasmic zinc. Moreover, related studies revealed that intracellular zinc could regulate Shank3/PKCε pathway, which could decrease the expression of mucosal tight junction proteins. Accordingly, we propose our scientific hypothesis that decreased expression of ZIP7 in IBD intestinal mucosa inhibits Shank3/PKCɛ pathway, which induces increased mucosal permeability and bowel inflammation. This project bases on IBD patients, animal model and colitis cells, and intends to explore: ①the effect of ZIP7 on mucosal barrier and intestinal inflammation; ②the mechanism that ZIP7 regulates intracellular zinc release and inhibits Shank3/PKCɛ pathway. Our project is expected to provide a novel mechanism and a new treatment target for IBD.

黏膜屏障失调在炎症性肠病（IBD）的发展中起关键作用，锌稳态是调节黏膜屏障的重要机制。课题组前期研究发现锌离子转运蛋白7（ZIP7）在IBD肠黏膜的表达呈现炎症相关性的降低，上调ZIP7表达可恢复黏膜屏障完整性并缓解肠道炎症，目前尚未见报道。ZIP7作为锌离子转运蛋白家族唯一直接转运游离锌离子的蛋白，其表达下调引起肠黏膜细胞内锌离子减少。相关研究表明细胞内锌离子可调控Shank3/PKCε通路，后者可影响黏膜紧密连接蛋白表达。据此提出科学假说：IBD患者肠黏膜ZIP7表达降低导致细胞内锌离子减少，抑制Shank3/PKCɛ通路，损坏肠黏膜屏障并促进肠道炎症。本课题以临床标本、动物及肠炎细胞为研究对象，探索①ZIP7对IBD黏膜屏障及肠道炎症的影响；②ZIP7调控细胞内锌离子释放对Shank3/PKCɛ通路的调节机制，本课题有望揭示新的IBD发生发展机制，为其治疗提供新的靶点。

炎症性肠病（Inflammatory bowel disease, IBD）是一种慢性肠道非特异性炎症性疾病，具有终生复发迁延进展的特点，反复的炎症活动不但影响患者的生存期及生活质量，还可带来沉重的社会经济负担。黏膜屏障失调在IBD的发生发展中起关键作用，锌稳态失调是导致黏膜屏障破坏及肠道炎症的重要机制。以往研究均集中于血清锌离子，肠黏膜细胞内锌离子的作用在肠道炎症中可能发挥着更为直接重要的作用，然而以往研究中未见报道，其具体机制也并不明确。本课题组研究发现IBD患者存在肠道特异性锌离子的减少，并与黏膜屏障失调显著相关；而细胞内锌离子释放的调控蛋白锌离子转运蛋白7（Zinc transporter protein7，ZIP7）在IBD肠黏膜中的表达呈现炎症相关性的降低，上调ZIP7的表达可缓解肠道炎症并恢复黏膜屏障完整性。此外，相关研究表明细胞内锌离子可通过活化Shank3/PKCε通路调节黏膜紧密连接蛋白，从而可能在IBD黏膜屏障维持中发挥重要作用。本项目以临床标本、肠炎细胞及动物模型为研究对象，通过多种生物学手段揭示：ZIP7与肠道炎症密切相关，ZIP7通过调控细胞内锌离子释放影响Shank3/PKCɛ通路，从而维持IBD的黏膜屏障。此外，本项目构建了ZIP7基因单敲除的小鼠，为后续研究提供了保障。本项目的科学意义在于揭示了ZIP7介导锌离子释放调控Shank3/PKCɛ通路从而引起IBD黏膜屏障失调的新机制，为IBD的治疗提供新的候选靶点与思路。