染色质重塑ATP酶BRG1通过调控ILC3影响肠道炎症性疾病的分子机制

3型天然淋巴细胞(ILC3)属于固有淋巴细胞亚群，富集于肠粘膜固有层并对肠道免疫有重要调控作用。BRG1是有ATP酶活性的染色质重塑复合体SWI/SNF家族BAF的重要组分，可通过调控染色质结构改变基因转录活性。BRG1对ILC3及肠道炎症性疾病的影响还不清楚。我们通过构建在ILC3中特异性敲除Brg1的小鼠(Brg1cKO小鼠)，初步发现Brg1cKO小鼠NCR+ILC3分化缺陷；Brg1cKO小鼠的ILC3增殖旺盛、比例增加；Rag1-/-背景的Brg1cKO小鼠发生自发性肠炎，伴随ILC3表达GM-CSF升高，提示BRG1可通过调控ILC3影响肠炎的发生进展。本项目拟利用小鼠肠炎模型、细胞过继转移、体外细胞共培养、分子生物学技术结合多组学分析等方法，解析BRG1通过调控ILC3从而影响肠炎发生发展的分子机制，并探索其与肠道微环境的互作网络，以期为肠道炎症性疾病的治疗提供新策略。

Group 3 innate lymphoid cell (ILC3) is a subset of ILC that lack T or B cell antigen-specific receptors. ILC3s are abundantly present in the intestine and play an important role in the regulation of intestinal immunity. BRG1 is a catalytic subunit of the BAF complex, which belongs to the family of SWI/SNF chromatin remodeling complex. The ATPase activity of BRG1 is essential for BAF to regulate the nucleosome deposition, which modulates the accessibility of the chromatin and gene transcription. BRG1 has been found to be required for the development of various types of cells, including immune cells such as T and B cells. The regulation of ILC3s and intestinal immunity by BRG1 remains unknown. .By crossing brg1flox/flox mouse to RORc-cre and /or Rag1-/- background, we generated the mice with Brg1 deficiency specifically in T cells and ILC3s (Brg1flox/floxRORc-cre), or only ILC3s (Rag1-/-brg1flox/floxRORc-cre). We briefly described these mice as Brg1cKO(conditional knockout) mice. We found that Brg1cKO mice had increased proportion of ILC3s among lineage negative (Lin-, CD3-B220-CD11b-CD11c-) cells in the small intestine. By construction of bone marrow chimeric mice, we observed increased rate of proliferative cells in Brg1KO ILC3s compared to controls, which may be the mechanisms for the increased percentages of ILC3s in Brg1cKO mice. Importantly, Rag1-/-Brg1flox/floxRORc-cre mice developed spontaneous intestinal inflammation at 8 weeks old of age. This was accompanied by increased GM-CSF production by ILC3s and the infiltration of pro-inflammatory myeloid cells in the intestine. The above data suggest BRG1 may prevent intestinal inflammation by suppression of the proliferation and GM-CSF production by ILC3s. .In addition, percentage of NCR+ILC3s was decreased in Brg1cKO mice in the small intestine. Consistently, we observed reduced conversion of NCR-ILC3s to NCR+ILC3s in absence of BRG1 in an in vitro differentiation system, indicating this process is controlled by BRG1..In this proposal, we aimed to unveil the molecular regulation of ILC3s by BRG1 and the impact of this regulation on intestinal inflammation. By utilizing mouse models of colitis, adoptive cell transfer, in vitro cell differentiation system, as well as molecular technologies (RNA-seq, ATAC-seq and ChIP-seq) together with bioinformatics analysis, we are going to determine the mechanism involved in the modulation of development and function of ILC3s and intestinal inflammation by BRG1. We also plan to examine the effect of regulation of ILC3s by BRG1 on other types of immune cells and microbiota, therefore extend this work to a tissue microenvironment scope of view. The elaboration of key targets in the regulation of ILC3s by BRG1 is valuable for understanding the pathology of intestinal inflammation, and provides potential means for the treatment of intestinal inflammatory diseases.