Glycoprotein A repetitions predominant, a Treg-specific molecule, in autoimmune inflammation

类风湿性关节炎（RA）是一种慢性全身性炎症性自身免疫性疾病，其特征是调节性T细胞（Tcells，Tcells）功能不全，随后效应性T细胞不受控制地扩增。为了便于详细分析导致RA中Treg功能受损的分子机制，我们先前已经对TcR进行了基因芯片分析，并将糖蛋白A重复占主导地位（GARP）确定为新的特异性Treg表面分子。GARP的功能分析揭示了GARP在Treg功能中的作用，因为GARP的表达减少与Treg功能受损相关。在自身免疫性疾病的病理生理学意义上，GARP表达在RA中减少。这一观察结果结合最近的证据表明，RA中TARP的促炎性而非抗炎性表型强烈表明GARP及其表达改变在自身免疫性风湿性炎症发病机制中的潜在重要性。因此，详细研究GARP在RA中的作用以及导致RA中TARP中GARP表达减少的分子机制具有重要意义。在这里提出的项目中，我们将详细探索GARP在TCRs中的作用，通过采用各种方法来干扰TCRs中的GARP表达，以及加强效应T细胞中的GARP表达，并在功能上评估Treg功能，如增殖，细胞因子分泌或阻断效应T细胞活化。此外，我们将通过用不同的CD4 T细胞群（例如Th1、Th2和Th17细胞以及TcB）进行再分化实验来确定GARP在稳定Treg表型中的作用。由于GARP通过miRNA受到转录后调控的严格控制，我们计划对患者和对照组中GARP的3UTR进行深度测序分析，以深入了解RA中GARP调控的潜在机制。将通过评估具有不同自身免疫性疾病的临床明确定义的患者中的GARP表达并通过确定来自患者的TcRNA中不同miRNA的水平来完成分析。最后，我们将评估GARP的3 'UTR中的SNP是否会通过改变miRNA对GARP 3' UTR上靶序列的亲和力或通过将新的miRNA结合位点引入GARP 3 'UTR而导致患者中GARP的不同表达水平。总之，这些实验旨在详细了解GARP在T细胞中的作用，其调节机制及其对人类自身免疫性疾病的贡献。

Rheumatoid arthritis (RA) is a chronic systemic inflammatoryautoimmune disease, which is characterized by an incompetent function of regulatory T cells (Tregs) and, subsequently, an uncontrolled expansion of effector T cells. To facilitate detailed analyses of the molecular mechanisms resulting in impaired Treg function in RA, we have previously performed a gene chip analysis of Tregs and have identified glycoprotein A repetitions predominant (GARP) as a new and specific Treg surface molecule. Functional analysis of GARP has revealed a role of GARP in Treg function in that reduced expression of GARP is associated with impaired Treg function. Of pathophysiological interest for autoimmune diseases, GARP expression is diminished in RA. This observation in combination with the recent evidence of a pro-inflammatory rather than anti-inflammatory phenotype of Tregs in RA strongly suggests a potential importance of GARP and its altered expression in the pathogenesis of autoimmune rheumatic inflammation. It is therefore of great interest to investigate in detail the role of GARP in Tregs and the molecular mechanisms that result in diminished GARP expression in Tregs in RA. In the project proposed here we will explore in detail the role of GARP in Tregs by employing various methods to interfere with GARP expression in Tregs as well as to enforce GARP expression in effector T cells and functionally assess Treg function such as proliferation, cytokine secretion, or blocking effector T cell activation. Furthermore, we will define the role of GARP in stabilizing the Treg phenotype by performing redifferentiation experiments with distinct CD4 T cell populations (e.g. Th1, Th2, and Th17 cells as well as Tregs). As GARP is tightly controlled by posttranscriptional regulation through miRNAs we plan to perform deep sequencing analysis of the 3UTR of GARP in patients and controls to gain insight into potential mechanisms of GARP regulation in RA. The analyses will be completed by assessing GARP expression in clinically well-defined patients with distinct autoimmune diseases and by determining the level of different miRNAs in Tregs from the patients. Finally, we will assess whether SNPs in the 3´UTR of GARP will contribute to a different expression level of GARP in patients by altering the affinity of miRNAs for their target sequence on the GARP 3`UTR or by introducing novel miRNA binding sites into the GARP 3`UTR. Together, the experiments are desiged to gain detailed insight into the role of GARP in Tregs, ist mechanisms of regulation and its contribution to human autoimmune diseases.