The role of PU.1 in T helper 2 function

描述(申请人提供)：PU.1是一种ETS家族转录因子，对包括巨噬细胞、B细胞、肥大细胞和中性粒细胞在内的多种造血系的发育至关重要。PU.1缺陷小鼠的T细胞发育减弱，早期致死性以及在多个嵌合体模型中无法产生PU.1缺陷T细胞阻碍了对PU.1在成熟T细胞中作用的分析。PU.1的表达模式往往与GATA家族因子的表达模式相反。由于GATA3的表达在T辅助细胞发育过程中受到调节，因此我们研究了PU.1在T辅助细胞亚群中的表达。与之前关于PU.1在T细胞中不表达的观察结果相矛盾的是，我们观察到PU.1在Th2细胞中表达，但在Th1细胞中不表达。值得注意的是，PU.1在Th2细胞因子表达较低的Th2培养群体中表达。此外，PU.1逆转录病毒在Th2人群中的表达减少了Th2细胞因子的分泌。初步实验表明，PU1可能通过干扰GATA3功能来调节Th2表型。本应用的目的是明确PU.1在Th2调节中的作用，并阐明干扰Th2表型发育的机制。我们的假设是PU1是Th2功能的重要调节因子。我们将通过检测以PU.1基因为靶标的小鼠来研究这个问题，并通过评估体外和体内T辅助细胞群的发展来确定Th2的表型。我们还将研究Th2细胞中PU1功能的结构要求，以及PU1如何调节GATA3和其他Th2调节因子功能。我们已确定PU1是Th2细胞因子分泌的Th2限制性负调控因子。调节PU1的表达和功能可用于治疗Th2介导的疾病，包括哮喘和过敏。

DESCRIPTION (provided by applicant): PU.1 is an ETS family transcription factor that is crucial for the development of multiple hematopoietic lineages including macrophages, B cells, mast cells and neutrophils. T cell development in PU.1-deficient mice is attenuated and the early lethality as well as the inability to generate PU.1-deficient T cells in multiple chimera models has hampered the analysis of the role of PU.1 in mature T cells. PU.1 expression patterns often appear opposite that of GATA family factors. Since GATA3 expression is modulated during T helper cell development, we investigated PU.1 expression in T helper subsets. Contradicting previous observations that PU.1 is not expressed in T cells, we observed PU.1 expression in Th2 cells but not in Th1 cells. Strikingly, PU.1 is expressed in populations of Th2 cultures that have low expression of particular Th2 cytokines. Furthermore, retroviral expression of PU.1 in Th2 populations decreases secretion of Th2 cytokines. Preliminary experiments suggest that PU.1 may regulate the Th2 phenotype by interfering with GATA3 function. The goal of this application is to define the role of PU.1 in Th2 regulation and to elucidate the mechanism of interference with the development of the Th2 phenotype. Our hypothesis is that PU.1 is an important regulator of Th2 function. We will investigate this issue by examining PU.1 gene targeted mice and determining the Th2 phenotype by assessing both in vitro and in vivo T helper cell population development. We will also examine the structural requirements for PU.1 function in Th2 cells and how PU.1 may regulate GATA3 and other Th2-regulating factor function. We have identified PU.1 as a Th2-restricted negative regulatory factor of Th2 cytokine secretion. Regulation of PU.1 expression and function could be manipulated as a treatment for Th2 mediated diseases including asthma and allergies.