Regulation of ROR-gt in colonic inflammation

摘要 ROR-γ t介导的IL-17表达失调与慢性炎症密切相关。但 ROR-γt发挥功能的分子机制及其稳定性如何调节仍然是未知的。我们 初步研究表明，在肠道稳态条件下，ROR-γt在Th 17细胞中被SUMO化， UBC 9（SUMO-E2连接酶）和TRIM 55（SUMO-E3连接酶）。此外，我们发现，在稳态下， 条件下，一种新的NCOA 6-HDAC 2阻遏物复合物与ROR-γt结合。在T细胞受体刺激后， 类小泛素化去除该阻遏物复合物，导致IL-17转录。为了防止延长的Th 17 在刺激后的反应中，ROR-γt被激酶Pak 2磷酸化，这促进了瘙痒介导的炎症反应。 ROR-γt泛素化和随后的降解。基于这些发现，我们假设， ROR-γt的泛素化和类小泛素化是调节Th 17应答的关键分子事件， 成为治疗目标。在AIM 1中，我们将确定ROR-γ的sumoylation的机制， 抑制IL-17转录。通过使用新产生的CD 4 T细胞特异性TRIM 55-/-小鼠，我们将研究 NCOA 6/HDAC 2复合物利用组蛋白去乙酰化抑制IL-17表达的机制。 在AIM 2中，我们将确定磷酸化促进瘙痒介导的ROR-γt的机制。 泛素化使用Pak 2-/-小鼠，我们将研究磷酸化依赖的构象变化 促进其降解。在AIM 3中，我们将靶向Itch-ROR-γt-IL-17通路以抑制过度的 炎症我们将测试小分子瘙痒激活剂抑制结肠炎的治疗潜力， 炎症这些研究的完成将导致对分子机制的清晰理解， 其ROR-γt功能及其稳定性受到调节以防止慢性炎症。这些知识将引导 涉及靶向人炎性疾病中的ROR-γt-IL-17途径的改进的治疗策略。

ABSTRACT Dysregulated ROR-γt-mediated IL-17 expression is strongly associated with chronic inflammation. However, the molecular mechanisms by which ROR-γt functions and how its stability is regulated remain elusive. Our preliminary studies suggest that under steady-state conditions in the gut, ROR-γt is sumoylated in Th17 cells by UBC9 (SUMO-E2 ligase) and TRIM55 (SUMO-E3 ligase). Additionally, we found that under steady-state conditions, a novel NCOA6-HDAC2 repressor complex binds to ROR-γt. Upon T cell receptor stimulation, de- sumoylation removes this repressor complex, resulting in IL-17 transcription. To prevent a prolonged Th17 response following stimulation, ROR-γt is phosphorylated by the kinase Pak2, which promotes Itch-mediated ROR-γt ubiquitination and subsequent degradation. Based on these findings we hypothesize that that ubiquitination and sumoylation of ROR-γt are critical molecular events that regulate Th17 responses and that can be targeted therapeutically. In AIM 1, we will determine the mechanism by which sumoylation of ROR-γt represses IL-17 transcription. By using newly generated CD4 T cell-specific TRIM55-/- mice, we will investigate the mechanism by which the NCOA6/HDAC2 complex utilizes histone deacetylation to repress IL-17 expression. In AIM 2, we will determine the mechanism by which phosphorylation promotes Itch-mediated ROR-γt ubiquitination. Using Pak2-/- mice, we will investigate how the phosphorylation-dependent conformational change of ROR-γt promotes its degradation. In AIM 3, we will target the Itch-ROR-γt-IL-17 pathway to inhibit excessive inflammation. We will test the therapeutic potential of a small-molecule Itch activator to inhibit colonic inflammation. Completion of these studies will lead to a clear understanding of the molecular mechanisms by which ROR-γt function and its stability are regulated to prevent chronic inflammation. This knowledge should lead to improved therapeutic strategies to target the ROR-γt-IL-17 pathway in human inflammatory diseases.