树突状细胞泛素连接酶ZFP91维持肠道免疫稳态的机制

The interplay between immune stimulatory and suppressive activities of intestinal dendritic cells is vital for both the induction of an immune response and the maintenance of local immune tolerance. The elucidation of signaling mechanisms that govern mucosal dendritic cell activity is crucial to better understand the aberrant immune responses associated with intestinal disorders, including inflammatory bowel disease. Our previous studies revealed the molecular mechanism underlying regulatory T cells-induced immune tolerance by SUMO-specific protease 3 (SENP3) or lysosomal TRAF3IP3. Recently, we found that DCs-specific deletion of ZFP91 (an E3 ubiquitin-protein ligase) mice exhibited auto-colitis and intestinal immune homeostasis-related cytokines showed significant down-regulation. This implies that ZFP91 in DCs plays an important role in maintaining gut immune homeostasis. In this application, we propose to investigate the function of ZFP91 in DCs-mediated gut immune homeostasis and colitis. We will further delineate ZFP91-mediated signaling pathway in DCs. Furthermore, we will identify the target of ZFP91 in DCs and define its function. Our study not only holds promise for opening a new window for understanding IBD pathogenesis, but also provides new therapeutic targets for the development of anti-IBD drugs.

肠道树突状细胞（DCs）免疫激活与抑制活性的调控在介导免疫应答和诱导免疫耐受方面发挥重要作用，其调控机制的解析对于深入认识炎症性肠病至关重要。申请人的研究结果已揭示去类泛素化连接酶SENP3和溶酶体膜上的跨膜分子TRAF3IP3介导调节性T细胞促进肿瘤免疫耐受的分子机制。本项目初步结果显示：DCs条件性基因敲除E3泛素连接酶ZFP91小鼠自发产生肠炎，DCs中ZFP91的缺失导致肠道免疫稳态相关的免疫抑制分子显著下调，提示ZFP91在DCs介导的免疫耐受维持肠道免疫稳态中起着重要作用。鉴于此，本项目拟分三个层面展开研究：1.揭示DCs中ZFP91在细胞和动物水平上的功能；2.解析ZFP91介导DCs维持肠道免疫稳态的分子机制；3.探究DCs中ZFP91作用的新靶点及其功能。本项目期望为理解IBD的发病机制提供新思路，为开发IBD的治疗药物提供新靶标。

肠道树突状细胞（DCs）免疫激活与抑制活性的调控在介导免疫应答和诱导免疫耐受方面发挥重要作用，其调控机制的解析对于深入认识炎症性肠病至关重要。申请人的研究结果已揭示SUMO特异性蛋白酶SENP3和溶酶体膜上的跨膜分子TRAF3IP3介导调节性T细胞促进肿瘤免疫耐受的分子机制。本项目在前期基础上试图应用DSS诱导的急性肠炎模型和AOM/DSS诱导的肠炎相关的肠癌去研究树突状细胞中翻译后修饰酶ZFP91在肠道稳态维持中的功能，但是在两种模型中不论是动物表型还是细胞表型都揭示了DCs条件性基因敲除ZFP91小鼠在肠炎发生和肠炎相关肠癌发生中的作用均不显著，故终止了DCs中ZFP91在肠道稳态维持中的机制研究。其次，本研究应用了体外HEK293瞬时转染实验、Ni-NTA亲和层析及免疫共沉淀分析实验、体内的SUMO化分析实验及IFI204的SUMO化位点分析实验解析了DCs中SENP3介导IFI204的在K83位点的去SUMO化，为研究DCs中IFI204去SUMO化促进胞质DNA介导的STING信号通路，从而增强DCs抗肿瘤功能的激活奠定坚实的分子基础。以此研究为基础的研究成果发表于Molecular Cell (2021)。