Il2 Receptors--molecular Regulation

人们正在研究人类白介素2受体，以了解正常细胞和肿瘤细胞中T细胞免疫反应的关键成分。T细胞激活后，IL-2和IL-2受体被诱导；T细胞免疫反应的大小和持续时间由IL-2产生的量、受体的表达水平和这些事件的时间进程控制。IL-2受体存在三条链，即IL-2Ra、IL-2Rb和GC，其中IL-2Ra和IL-2Rb在转录水平上受到显著调控。该小组主要关注IL-2诱导的信号类型，特别是STAT蛋白(信号转导和转录激活剂)的激活，以及它们调节IL-2ra基因的机制。Stat5a和Stat5b是两个密切相关的蛋白质，它们被IL-2激活，具有90%的氨基酸同源性。一个重要的问题是，这些密切相关的蛋白质在它们的作用中是多余的还是独特的。为了澄清这个问题，已经产生了Stat5a和Stat5b转基因小鼠来重建基因敲除小鼠。研究发现，Stat5蛋白在调节CD8+T细胞动态平衡中起着重要作用。Stat5a和Stat5b是位于头对头方向的相邻基因。人们正在研究这些基因在调控方面的相似性和差异性。IL-2ra基因有两个IL-2反应元件，一个在5‘调控区，另一个在第一内含子。这第二个调控元件，标记为PRRIV，据报道也是TCR反应元件。该元件在人类和小鼠中高度保守，位于第一内含子。该元件不仅受Stat5和HMG-I(Y)蛋白的调控，还受NFAT和AP1位点的调控。内含子元件与上游元件一起控制IL-2介导和TCR介导的对IL-2ra基因的调控。总之，这些研究大大加强了我们对IL-2R表达和Stat5依赖的基因调控的基础的理解。

The human interleukin-2 receptor is being studied to understand critical components of the T cell immune response in normal and neoplastic cells. Following T-cell activation, IL-2 and IL-2 receptors are induced; the magnitude and duration of the T-cell immune response is controlled by the amount of IL-2 produced, the levels of receptors expressed, and the time course of these events. Three chains of the IL-2 receptor exist, IL-2Ra, IL-2Rb, and gc, with IL-2Ra and IL-2Rb being significantly regulated at the level of transcription. The group has focused primarily on the types of signals induced by IL-2, particularly the activation of STAT proteins (signal transducers and activators of transcription), and the mechanism by which they regulate the IL-2Ra gene. Stat5a and Stat5b are two closely related proteins with >90% amino acid identity that are activated by IL-2. An important issue is whether these closely related proteins are redundant or distinctive in their actions. To attempt to clarify this issue, Stat5a and Stat5b transgenic mice have been generated to reconstitute the knockout mice. A major role for Stat5 proteins in regulating CD8+ T cell homeostasis was discovered. Stat5a and Stat5b are adjacent genes located in a head-to-head orientation. Aspects of similarities vs. differences in regulation of these genes is being studied. Two IL-2 response elements in the IL-2Ra gene were previously reported, one in the 5' regulatory region and the other in the first intron. This second regulatory element, denoted PRRIV, was reported to be a TCR response element as well. This element is highly conserved in humans and mice and is located in the first intron. This element is regulated not only by Stat5 and HMG-I(Y) proteins but also by NFAT and AP1 sites. Together with the upstream elements, the intronic element controls IL-2-mediated and TCR-mnediated regulation of the IL-2Ra gene. Together, these studies substantially enhance our understanding of the basis of IL-2R expression and Stat5-dependent gene regulation.