Regulation of HIV by T-Cell Signal Transduction

描述（由申请人提供）：T细胞活化通过T细胞受体和共刺激分子如CD28已被证明影响T细胞对HIV-1感染的易感性和调节前病毒转录。然而，由T细胞受体复合物和CD28发起的直接影响HIV-1转录的信号事件尚未被探索。特别是，目前尚不清楚CD28信号如何潜在地增强和抑制HIV-1表达。该项目的目的是确定CD28调节HIV-1转录的机制，并检查HIV-1 Nef和CD28信号之间的相互作用。我们假设CD28参与导致不同的信号级联反应，这些信号级联反应对HIV-1的表达有非常不同的影响，并且HIV-1编码的蛋白Nef通过与CD28信号级联反应的不同组分相互作用导致异常的T细胞信号和功能。我们使用嵌合CD28受体的初步数据，包括关键酪氨酸残基的突变，以及阻断特定信号转导途径的抑制剂，支持这样的模型。此外，这些初步实验表明，磷脂酰肌醇-3激酶通过依赖tat的机制抑制hiv -1转录。我们建议扩展这些研究，并使用细胞系、初级系统和生化方法来进一步表征CD28的差异信号在调节HIV-1转录中的作用，2)表征介导LTR活性的顺式元件和转录因子，以响应CD28信号，3)确定Nef是否直接或间接改变CD28信号。了解CD28调节HIV-1转录的机制将进一步确定与该受体相关的途径，并确定对控制HIV-1表达至关重要的推定上游信号转导事件。此外，操纵这些途径的能力可能为控制病毒表达提供独特的治疗靶点。

DESCRIPTION (provided by applicant): T cell activation through the T cell receptor and costimulatory molecules such as CD28 has been demonstrated to influence the susceptibility of T cells to HIV-1 infection and regulate proviral transcription. However, the signaling events initiated by the T cell receptor complex and CD28 that /directly impact HIV-1 transcription have not been explored. In particular, it is unclear how CD28 signaling potentially enhances and inhibits HIV-1 expression. The objective this project is to determine the mechanisms by which CD28 regulates HIV-1 transcription, and to examine the interaction between HIV-1 Nef and CD28 signals. We hypothesize that CD28 engagement results in distinct signaling cascades that have very different consequences for HIV-1 expression and that the HIV-1 encoded protein Nef contributes to aberrant T cell signaling and function by interacting with different components of the CD28 signaling cascade. Our preliminary data using chimeric CD28 receptors that include mutations in critical tyrosine residues as well as inhibitors that block specific signal transduction pathways supports such a model. Furthermore, these initial experiments demonstrate phophatidylinositol-3-kinase inhibits H IV-1 transcription by a Tat-dependent mechanism. We are proposing to extend these studies and use cell lines, primary systems and biochemical approaches to 1) further characterize the role of differential signals from CD28 in regulating HIV-1 transcription, 2) characterize cis-elements and transcription factors that mediate induction of LTR activity in response to CD28 signals and 3) determine if Nef directly or indirectly alters CD28 signaling. Understanding the mechanisms by which CD28 regulates HIV-1 transcription will further define pathways associated with this receptor as well as identify putative upstream signal transduction events critical for controlling HIV-1 expression. Furthermore, the ability to manipulate these pathways may provide unique therapeutic targets for controlling virus expression. Relevance of this research to public health: We are proposing to identify and characterize cellular events that influence the production of HIV. Manipulating these cellular pathways may provide novel strategies that would complement current treatments to control HIV as well as approaches to purge latent HIV reserviors.