Examining a role for G alpha q in preventing autoimmune disease

描述(申请人提供)：编码GαQ(Gaq-/-)，异源三聚体GTP酶组的成员，在重组后2个月内产生自身抗体。在混合了WT和Gaq-/-BM的嵌合小鼠中，缺乏Gaq的激活的T细胞在体内积累得比激活的B细胞更快，并且在自身抗体出现之前。此外，年龄较大的嵌合体显示出更高的死亡率。这表明缺乏GAQ的造血细胞比WT造血细胞具有选择性优势。此外，缺乏GAQ的胸腺细胞比WT胸腺细胞占优势。我们的目标是阐明GAQ缺失是如何导致自身抗体的产生的。我们假设缺乏Gaq的胸腺细胞和T细胞对细胞死亡更有抵抗力，导致它们在体内积累，从而驱动B细胞产生自身反应性抗体和随后的自身免疫。我们的目标是(1)确定Gaq-/-胸腺细胞和T细胞是否对凋亡刺激更具抵抗力，从而导致它们选择性存活；(2)确定Gaq基因缺失是否会产生活化的、抵抗细胞死亡并在体内积累的外周CD4+和CD8+T细胞；(3)评估Gaq-/-T细胞是否只对自身免疫性疾病的发生负责。通过分离Gaq-/-和WT T细胞和胸腺细胞，并将它们置于不同形式的凋亡诱导刺激下，我们将确定Gaq淋巴样细胞是否比WT淋巴样细胞具有选择性生存优势。这也将使我们能够确定Gaq-/-T细胞在哪个发育阶段获得优势。我们还将检查几个促凋亡和抗凋亡基因的表达，以确定Gaq-/-T细胞是否天生比WT T细胞更有可能抵抗细胞死亡。最后，我们将把来自Gaq-/-动物的T和/或B细胞转移到WT宿主中，以确定是否有一种或两种细胞类型驱动了自身免疫的产生。通过完成这些目标，我们将确定GAQ缺乏导致自身免疫性疾病产生的新机制。 公共卫生相关性：通过了解GAQ如何控制免疫细胞的存活，我们将确定允许维持潜在的自身反应性T和B细胞的因素。这将有可能为治疗自身免疫性疾病确定新的药物靶点，这种疾病影响着1470万到2350万美国人。因此，这项提案产生的数据与改善许多美国人的健康直接相关。

Description (provided by applicant): Encoding G alpha q (Gaq-/-), a member of the heterotrimeric GTPase group, develop autoantibody within 2 months of reconstitution. In chimeric mice made with mixed WT and Gaq-/- BM, activated T cells lacking Gaq accumulate in vivo more rapidly than activated B cells and prior to the appearance of autoantibody. Additionally, older chimeras display increased mortality. This suggests that hematopoietic cells lacking Gaq have a selective advantage over WT hematopoietic cells. Additionally, thymocytes lacking Gaq predominate over WT thymocytes. Our goal is to elucidate how the lack of Gaq leads to development of autoantibody. We hypothesize that thymocytes and T cells lacking Gaq are more resistant to cell death, leading to their accumulation in vivo, which drives autoreactive antibody production by B cells and subsequent autoimmunity. Our aims are (1) to determine if Gaq-/- thymocytes and T cell are more resistant to apoptotic stimuli, leading to their selective survival, (2) to determine whether the absence of the Gaq gene generates activated peripheral CD4+ and CD8+ T cells that are resistant to cell death and accumulate in vivo, and (3) to assess whether Gaq-/- T cells are exclusively responsible for driving the generation of autoimmune disease. By isolating Gaq-/- and WT T cells and thymocytes and subjecting them to various forms of apoptosis-inducing stimuli, we will determine whether Gaq lymphoid cells have a selective survival advantage over WT lymphoid cells. This will also allow us to determine at what stage of development Gaq-/- T cells gain their advantage. We will also examine the expression of several pro- and anti-apoptotic genes to determine whether Gaq-/- T cells are inherently more likely to resist cell death than WT T cells. Finally, we will transfer T and/or B cells from Gaq-/- animals into WT hosts to determine whether one or both cell types are driving the generation of autoimmunity. By completing these aims, we will determine the novel mechanism by which lack of Gaq leads to the generation of autoimmune disease. PUBLIC HEALTH RELEVANCE: By understanding how Gaq controls immune cell survival, we will identify factors that allow for the maintenance of potentially autoreactive T and B cells. This will potentially allow for the identification of new drug targets in treating autoimmune disease, which affects between 14.7 and 23.5 million Americans. Therefore, data generated from this proposal is directly relevant to improving the health of many Americans.