microRNA-dependent regulation of intestinal T-cells²

项目摘要 我们的肠道组成了我们身体免疫细胞的50%以上，并紧密地维持着 防止食物颗粒和细菌等外来刺激的动态平衡。这种免疫“耐受性”在 炎症性肠病(IBD)时可见的慢性肠炎。不良CD4+T细胞辅助者 反应使观察到的IBD的慢性病理持续存在，从而了解其分子机制 控制它们的功能是寻找新的治疗方法的核心。一种生理适应性 对炎症的反应是代谢物供应和需求的显著变化，导致有限的 氧可获得性(现在称为炎症性缺氧)和转录因子缺氧的激活- 诱因(HIF)。低氧对T细胞基因功能的影响是多方面的，而低氧对T细胞基因功能的影响是多方面的。 转录调控的研究还不够深入。研究低氧诱导的组织保护性信号转导 进行了CD4+T细胞特异性miRNAs的筛选，并鉴定了miR-29a的选择性诱导。研究 通过遗传模型确定了Hif-2α在miR-29a诱导中的作用，随后的实验证明 低氧时抑制miR-29a靶基因Tbet和干扰素γ的表达。有T-的小鼠 HIF-2α的细胞固有缺陷表现为Tbet水平升高，并加剧炎症 在实验性结肠炎期间。在这些初步研究的基础上，我们假设Hif-2α诱导miR- 29A抑制TH1的CD4+细胞活化。在本提案中，我们将通过三个集成的方案解决这一假设 调查的路线。首先，我们将研究Hif-2α是如何转录诱导miR-29a和功能 CD_4+T细胞分化对HIF-2α的要求第二，我们将评估miR-29a在 T细胞介导的结肠炎的调节。最后，在概念验证研究中，我们将把mir-29a稳定在 实验性结肠炎期间的活体。总的来说，这些研究旨在剖析HIF-2α-miR-29a-Tbet轴在 调节CD4+T细胞介导的肠炎症。 好了！

Project Summary Our intestines comprise over 50% of our bodies immune cells and tightly maintains a constant state of homeostasis against foreign stimulus like food particles and bacteria. This immune “tolerance” is broken during chronic intestinal inflammation as seen during inflammatory bowel diseases (IBD). Adverse CD4+ THelper responses perpetuate the chronic pathology observed in IBD, thus understanding the molecular mechanisms that control their function is central to endeavors of finding novel therapeutic treatments. A physiologic adaptive response to inflammation is a marked shift in the supply and demand of metabolites that results in limited oxygen availability (now termed inflammatory hypoxia) and activation of the transcription factors hypoxia- inducible-factors (HIFs). While there are multiple affects of hypoxia on T cell gene function, the effects on post- transcriptional regulation are underexplored. To investigate hypoxia-elicited tissue protective signaling we performed a screen of CD4+ T cell-specific miRNAs and identified a selective induction of miR-29a. Studies with genetic models identified a role of Hif-2α in miR-29a induction and subsequent experiments demonstrated repression of the miR-29a target-genes Tbet and IFNγ (canonical TH1 markers) during hypoxia. Mice with a T- cell-intrinsic deficiency in Hif-2α displayed elevated Tbet levels in CD4+ T cells and exacerbated inflammation during experimental colitis. Based on these preliminary studies, we hypothesize that Hif-2α induction of miR- 29a suppresses TH1 CD4+ cell activation. In this proposal we will address this hypothesis with three integrated lines of investigation. Firstly, we will examine how Hif-2α transcriptionally induces miR-29a and the functional requirements for Hif-2α in CD4+ THelper differentiation. Second, we will assess the role of miR-29a in the regulation of T cell mediated colitis. Lastly, in proof of concept studies we will target miR-29a stabilization in vivo during experimental colitis. Collectively these studies aim to dissect the Hif-2α-miR-29a-Tbet axis in the regulation of CD4+ T cell-mediated intestinal inflammation.! !