Regulation of HIV by T-Cell Signal Transduction

描述（由申请人提供）：已证明通过T细胞受体和共刺激分子（例如CD28）激活T细胞可以影响T细胞对HIV-1感染的易感性并调节前病毒转录。然而，由 T 细胞受体复合物和 CD28 引发的直接影响 HIV-1 转录的信号转导事件尚未被探索。特别是，目前尚不清楚 CD28 信号传导如何潜在地增强和抑制 HIV-1 表达。该项目的目标是确定 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，这些级联对 HIV-1 表达产生非常不同的结果，并且 HIV-1 编码的蛋白 Nef 通过与 CD28 信号级联的不同成分相互作用，导致异常的 T 细胞信号传导和功能。我们使用嵌合 CD28 受体（包括关键酪氨酸残基突变以及阻断特定信号转导途径的抑制剂）的初步数据支持了这样的模型。此外，这些初步实验表明磷脂酰肌醇-3-激酶通过 Tat 依赖性机制抑制 HIV-1 转录。我们建议扩展这些研究，并使用细胞系、原代系统和生化方法来 1) 进一步表征 CD28 的差异信号在调节 HIV-1 转录中的作用，2) 表征响应 CD28 信号介导 LTR 活性诱导的顺式元件和转录因子，以及 3) 确定 Nef 是否直接或间接改变 CD28 信号传导。了解 CD28 调节 HIV-1 转录的机制将进一步定义与该受体相关的途径，并确定对于控制 HIV-1 表达至关重要的假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。 这项研究与公共卫生的相关性：我们建议识别和表征影响艾滋病毒产生的细胞事件。操纵这些细胞途径可能会提供新的策略来补充当前控制艾滋病毒的治疗方法 以及清除潜在艾滋病毒储存库的方法。

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.