Regulation of ROR-gt in colonic inflammation

摘要 ROR-γT介导的IL-17表达异常与慢性炎症密切相关。然而， RoR-γt发挥作用的分子机制以及其稳定性是如何被调节的仍然难以捉摸。我们的 初步研究表明，在肠道的稳定状态下，ror-γt在Th17细胞中通过 UBC9(相扑-E2连接酶)和TRIM55(相扑-E3连接酶)。此外，我们发现在稳态下， 在此条件下，一种新型的NCOA6-HDAC2阻滞剂复合体与RoR-γt结合。 和甲基化去除了这个抑制物复合体，导致IL-17转录。为了防止Th17延长 刺激后的反应，RoR-γt被PK2磷酸化，从而促进了Ich介导的 RoR-γ泛素化和随后的降解。基于这些发现，我们假设 Ror-γt的泛素化和总甲基化是调节Th17反应的关键分子事件，可以 在治疗上成为靶子。在目标1中，我们将确定RoR-γt苏莫化的机制 抑制IL-17转录。通过使用新产生的CD4T细胞特异性TRIM55-/-小鼠，我们将研究 NCOA6/HDAC2复合体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Ich介导的RoR-γt的机制 泛素化。利用pak2-/-小鼠，我们将研究依赖于磷酸化的构象变化 RoR-γt的存在促进了其降解。在目标3中，我们将针对Ich-RoR-γt-IL-17途径来抑制过度 发炎。我们将测试一种小分子瘙痒激活剂抑制结肠的治疗潜力 发炎。这些研究的完成将导致对分子机制的清楚理解 通过调节ROR-γ的功能及其稳定性来预防慢性炎症。这一知识应该引导我们 改进针对人类炎症性疾病的RoR-γt-IL-17途径的治疗策略。

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.