Rescuing the anti-HIV activity of APOBEC3G with small-molecule chaperons

描述（由申请人提供）：在本提案中，我们计划评估开发基于人类细胞内在防御机制的抗病毒化疗策略的潜力：胞苷脱氨酶APOBEC3G （A3G）诱变单链DNA。人类免疫缺陷病毒1 （HIV-1）通过表达下调A3G活性和稳定性的病毒粒子感染因子（Vif）来对抗这种活性。Vif在病毒增殖中的重要作用和A3G的高度调控功能使它们的相互作用成为无耐药性干预的一个有吸引力的靶点。此外，通过a3g诱导的诱变在原位产生显性阴性HIV-1突变体的可能性提供了一个独特的机会来灭活潜伏感染细胞中的HIV，这些细胞通常是化疗药物无法进入的。提出的研究基于这样的假设，即能够与Vif竞争A3G的小分子将同时保护细胞因子免受Vif所表现出的拮抗作用，并降低病毒因子的稳定性。鉴定蛋白质-蛋白质相互作用的新生抑制剂的挑战将在本提案中通过利用遗传选择的独特力量来产生罕见的解决方案来解决。因此，我们相信，这一假设的实验验证提供了一个独特的机会，可以通过潜伏感染细胞中的自然防御机制来抑制HIV感染的进展，而不会产生抗性表型的危险。我们计划在制定这一方法时实现以下具体目标：

DESCRIPTION (provided by applicant): In this proposal, we plan to evaluate the potential for developing an antiviral chemotherapeutic strategy based on the intrinsic defense mechanism of human cells: mutagenesis of single-stranded DNA by cytidine deaminase APOBEC3G (A3G). Human immunodeficiency virus 1 (HIV-1) counters this activity by expressing virion infectivity factor (Vif) that downregulates both the activity and stability of A3G. The essential role of Vif in viral proliferation and highly regulated function of A3G make their interaction an attractive target for the resistance-free intervention. Furthermore, a possibility of generating dominant negative HIV-1 mutants in situ through A3G-induced mutagenesis presents a unique opportunity to inactivate HIV in latently infected cells, normally inaccessible to chemotherapeutics. The proposed research is based on the hypothesis that small molecules capable of competing with the Vif for A3G will simultaneously protect the cellular factor from the antagonism displayed by Vif and reduce stability of the viral factor. The challenge of identifying de novo inhibitors of protein-protein interaction will be addressed in this proposal by exploiting the unique power of genetic selection to yield rare solutions. We believe, therefore, that experimental validation of this hypothesis presents a unique opportunity for curbing the progression of HIV infections through a natural defense mechanism in latently infected cells without the danger of evolving resistant phenotypes. We plan to accomplish the following Specific Aims in developing this approach: Specific Aim 1: We will develop and implement a genetic selection scheme for the discovery of potent and selective antagonists of Vif-A3G interaction. Specific Aim 2: We will confirm and characterize Vif-degrading and/or A3G-protecting activities of the selected backbone cyclic peptides using a series of biochemical and cellular assays. Specific Aim 3: We will identify functional motifs important for the activity of the selected sequences and develop their cell-permeable derivatives. The expected outcome of this research will be a series of specific and potent cell-permeable agents capable of protecting A3G from the downregulation by Vif. Our long-term objective is to advance a prototype of a new class of anti-HIV drugs that can address the three existing problems associated with the current strategies: toxicity, resistance and latency. To protect organism against viral infections, human cells have developed a sophisticated defense mechanism involving modifications of viral genes, lethal to virus replication. Unfortunately, human immunodeficiency virus (HIV) is able to counteract this intrinsic protective system making the disease that it causes, Acquired Immunodeficiency Syndrome (AIDS), a global health problem, with no cure or prevention in sight. We propose to develop a novel anti-HIV therapeutic strategy that will rescue the natural antiviral mechanism without the danger of producing drug-resistant viruses.