Regulation of HIV by T-Cell Signal Transduction

描述(申请人提供)：通过T细胞受体和CD28等共刺激分子激活T细胞已被证明影响T细胞对HIV-1感染的易感性，并调节前病毒转录。然而，由T细胞受体复合体和CD28启动的直接影响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的表达。本项目的目的是确定CD28调控HIV-1转录的机制，并研究HIV-1Nef和CD28信号之间的相互作用。我们假设CD28的参与导致了不同的信号级联反应，对HIV-1的表达产生了非常不同的后果，并且HIV-1编码的蛋白Nef通过与CD28信号级联反应的不同成分相互作用而导致T细胞信号和功能的异常。我们使用嵌合CD28受体的初步数据支持这种模型，该受体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。此外，这些初步实验表明，磷脂酰肌醇-3-激酶通过TAT依赖的机制抑制HIV-1的转录。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1)进一步表征来自CD28的差异信号在调节HIV-1转录中的作用，2)表征顺式元件和转录因子，这些顺式元件和转录因子介导对CD28信号的诱导，以及3)确定Nef是否直接或间接改变CD28信号。了解CD28调控HIV-1转录的机制将进一步确定与该受体相关的途径，并识别对控制HIV-1表达至关重要的可能的上游信号转导事件。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。 这项研究与公共卫生的相关性：我们建议识别和描述影响艾滋病毒产生的细胞事件。操纵这些细胞通路可能会提供新的策略，补充目前控制艾滋病毒的治疗方法 以及清除潜伏的艾滋病毒储备者的方法。

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.