Institute of Biology and Medicine, College of Life and Health Sciences, Wuhan University of Science and Technology, Wuhan, Hubei, 430081, PR China.
Shenzhen Ritzcon Biological Technology Co., LTD, Shenzhen, Guangdong, 518000, PR China.
Cell Commun Signal. 2020 Jul 9;18(1):107. doi: 10.1186/s12964-020-00574-1.
Foxp3CD4 regulatory T cells (Treg) constitutes a key event in autoimmune diseases. STAT5b is the critical link between the IL-2/15 and FOXP3, the master regulator of Treg cells.
The CD3T cell and Foxp3CD4 regulatory T cells were overexpressioned or knockdown MKL-1 and STAT5a and tested for Treg cell development and function. Direct interaction of MKL-1 and STAT5a were analyzed by coimmunoprecipitation assays, Luciferase assay, Immunofluoresence Staining and Yeast two-hybrid screening. The effect of MKL-1 and STAT5a on the Treg genes expression was analyzed by qPCR and western blotting and Flow cytometry.
However, the molecular mechanisms mediating STAT5b-dependent Treg genes expression and Treg cell phenotype and function in autoimmune diseases are not well defined. Here, we report that the MKL-1 is a coactivator for the major Treg genes transcription factor STAT5b, which is required for human Treg cell phenotype and function. The N terminus of STAT5b, which contains a basic coiled-coil protein-protein interaction domain, binds the C-terminal activation domain of MKL-1 and enhances MKL-1 mediated transcriptional activation of Treg-specific, CArG containing promoters, including the Treg-specific genes Foxp3. Suppression of endogenous STAT5b expression by specific small interfering RNA attenuates MKL-1 transcriptional activation in cultured human cells. The STAT5b-MKL-1 interaction identifies a role of Treg-specific gene regulation and regulated mouse Treg cell development and function and suggests a possible mechanism for the protective effects of autoimmune disease Idiopathic Thrombocytopenic Purpura (ITP).
Our studies demonstrate for the first time that MKL-1 is a coactivator for STAT5b, the regulator of Treg cell development and function. Video abstract.
Foxp3CD4 调节性 T 细胞（Treg）是自身免疫性疾病中的关键事件。STAT5b 是 IL-2/15 和 FOXP3 之间的关键环节，FOXP3 是 Treg 细胞的主要调节因子。
过表达或敲低 MKL-1 和 STAT5a，检测 CD3T 细胞和 Foxp3CD4 调节性 T 细胞的 Treg 细胞发育和功能。通过共免疫沉淀分析、荧光素酶测定、免疫荧光染色和酵母双杂交筛选分析 MKL-1 和 STAT5a 的直接相互作用。通过 qPCR、western blot 和流式细胞术分析 MKL-1 和 STAT5a 对 Treg 基因表达的影响。
然而，介导 STAT5b 依赖性 Treg 基因表达和 Treg 细胞表型和功能的分子机制在自身免疫性疾病中尚未完全确定。在这里，我们报告 MKL-1 是主要的 Treg 基因转录因子 STAT5b 的共激活因子，它是人类 Treg 细胞表型和功能所必需的。STAT5b 的 N 端包含一个基本的卷曲螺旋蛋白-蛋白相互作用结构域，与 MKL-1 的 C 端激活结构域结合，并增强 MKL-1 对 Treg 特异性、包含 CArG 基序的启动子的转录激活，包括 Treg 特异性基因 Foxp3。特异性小干扰 RNA 抑制内源性 STAT5b 的表达可减弱培养的人类细胞中 MKL-1 的转录激活。STAT5b-MKL-1 相互作用确定了 Treg 特异性基因调控的作用，并调节了小鼠 Treg 细胞的发育和功能，并提示自身免疫性疾病特发性血小板减少性紫癜（ITP）的保护作用的可能机制。
我们的研究首次表明，MKL-1 是 STAT5b 的共激活因子，是 Treg 细胞发育和功能的调节因子。视频摘要。
