Chemokine Signaling and Colitis in Gia2 Deficient Mice

描述(由申请人提供)： 在MSTP资助的贝勒医学院解剖和临床综合病理学的MD/PhD培训、住院医师培训和董事会认证之后，Edwards博士目前正在密歇根大学进行为期一年的研究奖学金。这一修订的申请是在这两个机构进行研究的过程中提出的。它阐述了G蛋白偶联趋化因子信号在炎症性肠病Gia2缺陷小鼠模型中T细胞激活、运输和极化细胞因子产生中的作用。在小鼠中，G蛋白α亚单位Gia2的缺失会导致弥漫性结肠炎，这可能会发展为侵袭性腺癌，类似于人类溃疡性结肠炎。许多证据表明G蛋白偶联趋化因子信号在粘膜免疫中起中心作用。在临床疾病出现之前，来自Gia2(-/-)小鼠的T细胞自发地发展成Th1表型，产生高水平的Th1型细胞因子(TNFa、IFNG和IL12)。目前正在培育两个仅在CD4+T细胞或结肠上皮细胞中表达Gia2的转基因小鼠，并将用于研究Giα亚单位依赖的信号有助于维持T细胞对环境抗原的平衡反应的机制。上述野生型、Gia2(-/-)和转基因小鼠的T淋巴细胞亚群将被研究，以确定它们是否对Th1或Th2偏斜条件做出正常反应。这些细胞也将被用来确定特定的Giα亚基是否选择性地与已知参与T细胞激活和分化的趋化因子受体偶联。最后，将使用基因阵列、Tagman和RPA分析来筛选这些细胞的趋化因子和趋化因子受体表达模式的变化。在体外看到的反应将与小鼠品系中疾病的发展相关。这些实验将深入了解趋化因子受体与单个G蛋白α亚单位结合的特异性，以及Gia2的缺失如何导致易患结肠炎的趋化因子信号变化。这项申请得到了两个机构杰出导师的支持，这项申请的资金将促进爱德华兹博士作为一名内科科学家的继续发展。

DESCRIPTION (provided by applicant): Following MSTP-funded MD/ PhD training, residency and board certification in combined Anatomic and Clinical Pathology at Baylor College of Medicine, Dr. Edwards is currently conducting a year-long research fellowship at the University of Michigan. This revised application has been developed in the course of research performed at these two institutions. It address the role of G-protein coupled chemokine signaling in T-cell activation, trafficking, and polarized cytokine production in the Gia2-deficient mouse model of inflammatory bowel disease. Deletion of the G-protein alpha subunit Gia2 in mice produces diffuse colitis which can progress to invasive adenocarcinoma, mimicking human ulcerative colitis. Much evidence suggests a central role for G-protein coupled chemokine signaling in mucosal immunity. Before clincial disease is present, T-cells from Gia2 (-/-) mice spontaneously develop a Th1 phenotype, producing elevated levels of Th1-type cytokines (TNFa, IFNg, and IL12). Two new lines of transgenic mice expressing Gia2 only in CD4+ T-cells or colon epthelium are currently being produced and will be used to investigate the mechanisms whereby Gi alpha subunit- dependent signaling contribute to maintaining balanced T-cell responses to environmental antigen. T-lymphocyte subsets from wildtype, Gia2 (-/-), and transgenic mice as described above will be studied to identify whether they respond normally to Th1- or Th2- skewing conditions. These cells will also be used to determine whether particular Gi alpha subunits selectively couple with chemokine receptors known to be involved in T-cell activation and differentiation. Finally, these cells will be screened for changes in chemokine and chemokine receptor expression patterns using gene array, TagMan, and RPA analysis. The responses seen in vitro will be correlated with the development of disease in the strains of mice. These experiments will provide insight into the specificity with which chemokine receptors couple with individual G-protein alpha subunits, and how the loss of Gia2 may lead to alterations in chemokine signaling that predispose to colitis. This application has the support of outstanding mentors at two institutions, and funding of this application will foster Dr Edwards' continued development as a physician-scientist.