Function of microRNAs in controlling regulatory T cell biology

描述(由申请人提供)：维持正常的Foxp3+调节性T(Treg)细胞的动态平衡和抑制功能对于建立免疫耐受至关重要。最近，一类短的调控非编码RNA也被称为microRNAs(MiRNAs)，它在Treg细胞的发育和功能中起着关键作用。最近，我们发现选择性地去除Treg细胞中的miRNAs导致了自身免疫致死性的早期发生，与在没有Treg细胞的小鼠中观察到的结果很难区分。不同的miRNA表达谱，其中许多是Foxp3在Treg细胞中直接靶向的，进一步表明特定的miRNAs可以控制Treg生物学的不同方面。为此，我们先前的研究表明，Foxp3驱动的miR-155是维持正常Treg细胞动态平衡所必需的。在这一应用中，我们已经证明了在Treg细胞中高表达miR-146a对于通过靶向信号转导和激活转录1(STAT1)有效控制TH1反应是必不可少的。在Treg细胞中miR-146a的丢失导致总STAT1和磷酸化STAT1水平的增加。结果，带有miR-146a缺陷Treg细胞的小鼠死于依赖干扰素的I型免疫病理学。我们目前的结果提供了强有力的证据表明，除了Treg细胞的动态平衡外，Treg抑制功能也可以受到单个miRNA的调节。这项工作进一步表明，依赖于miRNA的转录后调控使Treg细胞能够控制特定类型的效应器T细胞反应。我之前的研究涉及使用广泛的分子和细胞手段，通过各种未经处理的小鼠品系和临床适用的模型，包括同种异体移植和不同的肿瘤系统，研究体液和细胞免疫反应。在鲁登斯基博士目前的指导下，在纪念斯隆-凯特琳癌症中心和包括威尔·康奈尔医学院和洛克菲勒大学在内的三机构生物医学研究社区的其他成员提供的丰富和资源丰富的环境下，我提议进行一项多方面的研究，利用遗传学、生化、免疫学方法和整体动物实验来研究依赖miRNA的转录后调控在Treg细胞介导的免疫耐受中的作用。再加上全面的职业发展计划，包括建立机构内和机构间的合作以及持续的培训和教育，这些因素无疑将促进我向独立研究的过渡，并使我能够成为世界顶尖研究机构之一的一名知名研究员。这些研究旨在促进对Treg细胞生物学中依赖miRNA的转录后调控的基本了解。此外，这些研究的结果将为操纵Treg细胞介导的抑制作为一种治疗移植、自身免疫和传染病以及肿瘤的新方法提供关键的见解。

DESCRIPTION (provided by applicant): Maintaining normal Foxp3+ regulatory T (Treg) cell homeostasis and suppressive function is essential for establishing immunological tolerance. Recently, a class of short regulatory non-coding RNAs also called as microRNAs (miRNAs) are shown to be pivotal in the development and function of Treg cells. Recently we have shown that selectively ablation of miRNAs in Treg cells resulted in the early onset of autoimmune lethality indistinguishable to those that were observed in mice devoid of Treg cells. Distinct miRNA expression profiles, of which many were directly targeted by Foxp3 in Treg cells further suggested specific miRNAs could control different facets of Treg biology. To this end, Foxp3-driven miR-155 is required for maintaining normal Treg cell homeostasis as demonstrated in our previous study. In this application, we have shown that high miR-146a expression in Treg cells is essential for effective controls of TH1 responses through targeting signal transducer and activator transcription 1 (STAT1). Loss of miR-146a in Treg cells resulted in increased levels of both total and phosphorylated STAT1. As a consequence, mice with miR-146a deficient Treg cells succumbed to IFN-?-dependent type I immunopathology. Our current results provided strong evidence suggesting that, in addition to homeostasis in Treg cells, Treg suppression function could also be regulated by a single miRNA. This work further implied that miRNA-dependent post-transcriptional regulation enables Treg cells to control a particular type of effector T cell responses. My previous research involved employing a wide spectrum of molecular and cellular means to study both humoral and cellular immune responses through both a variety of unmanipulated mouse strains and clinical-applicable models including allograft transplantation and different tumor systems. Under Dr. Rudensky's current mentoring and with the rich and resourceful environment provided by Memorial Sloan-Kettering Cancer Center and other members in the Tri-institutional biomedical research community including Weill Cornell Medical College and The Rockefeller University, I propose a multifaceted study employing genetic, biochemical, immunological approaches and whole animal experimentation to examine the role of miRNA-dependent post-transcriptional regulation in Treg cell-mediated immunological tolerance. Together with a comprehensive career development plan, including establishing intra- and inter-institutional collaborations and continued training and education, these elements will undoubtedly facilitate my transition to independent research and should allow me to become a well-established investigator in one of the world's top-research institutes. The proposed studies aim to facilitate basic understanding of miRNA-dependent post-transcriptional regulation in Treg cell biology. Furthermore, the results obtained from these studies will provide critical insights into manipulating Treg cell-mediated suppression as a novel therapeutic approach for transplantation, autoimmune and infectious diseases as well as tumors.