Phosphoinositide 3-Kinase Function in Lymphocytes

描述(申请者提供)：本项目的远景目标是 明确磷脂酰肌醇3-激酶(PI3K)信号转导机制 淋巴细胞。由于PI3K是淋巴细胞增殖所必需的，因此在这方面的进展 区域可能导致治疗免疫缺陷的新策略， 自身免疫、移植排斥和癌症。指导核心假说 这个应用是PI3K调节亚型p85α和p85β具有 淋巴细胞信号转导中不同的功能作用。为了检验这一假设， 这位研究员S的实验室已经产生了缺乏p85α或p85的小鼠 P85β。P85α缺陷小鼠表现出与所见类似的B细胞缺陷 在缺乏BTK、BLNK或PLCGamma2的小鼠中。这些发现支持一个模型，该模型 PI3K激活对于信号复合体的膜组装是重要的 促进PLCGamma2的激活和持续的钙离子流动。T细胞和B细胞 细胞依赖不同的蛋白质来执行许多信号步骤，这些步骤 将抗原受体与钙离子流量和细胞增殖联系起来。例如, T细胞内的钙离子流量受ITK调节，ITK是BTK的功能同源物。 初步结果提示p85β可能是一种重要的PI3K调节因子 T细胞信号转导中的异构体。这个应用程序有三个具体目标：目标1是 要测试激活BTK和PLCGamma2需要p85pha的模型 导致持续的钙离子流动。生化分析将被用来分析 缺乏p85α的原代B细胞和永生化B细胞系中的信号转导。 目的2是确定T细胞增殖和细胞因子是否需要p85β 制作。目标3是确定是否需要p85β来激活 ITK、PLCGamma1和T细胞持续的钙离子通量。生化分析将是 用于分析纯化的T细胞中的信号。这些研究将增加我们的 对淋巴细胞中枢控制点PI3K信号的认识 扩散。

DESCRIPTION (provided by applicant): The long-range goal of this project is to define the mechanism of phosphoinositide 3-kinase (PI3K) signaling in lymphocytes. As PI3K is required for lymphocyte proliferation, advances in this area may lead to novel strategies for the treatment of immunodeficiency, autoimmunity, transplant rejection and cancer. The central hypothesis guiding this application is that the PI3K regulatory isoforms p85alpha and p85beta have distinct functional roles in lymphocyte signaling. To test this hypothesis, this investigator?s laboratory has generated mice lacking either p85alpha or p85beta. p85alpha-deficient mice exhibit B cell defects similar to those seen in mice lacking Btk, BLNK or PLCgamma2. These findings support a model that PI3K activation is important for membrane assembly of a signaling complex that facilitates PLCgamma2 activation and sustained calcium flux. T cells and B cells rely on distinct proteins to carry out many of the signaling steps that link the antigen receptor to calcium flux and proliferation. For example, calcium flux in T cells is regulated by Itk, a functional homolog of Btk. Preliminary results suggest that p85beta may be an important PI3K regulatory isoform in T cell signaling. This application has three specific aims: Aim 1 is to test the model that p85alpha is required for activation of Btk and PLCgamma2 leading to sustained Ca2+ flux. Biochemical assays will be used to analyze signaling in primary B cells and immortalized B cell lines lacking p85alpha. Aim 2 is determine if p85beta is required for T cell proliferation and cytokine production. Aim 3 is to determine whether p85beta is required for activation of Itk, PLCgamma1, and sustained Ca2+ flux in T cells. Biochemical assays will be used to analyze signaling in purified T cells. These studies will increase our understanding of PI3K signaling, a central control point in lymphocyte proliferation.