Regulation of SAMHD1 antiviral activity

SAMHD1 抗病毒活性的调节

• 批准号: 8877038
• 负责人: Felipe Diaz-Griffero
• 金额: $ 28.76万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8877038
• 关键词: Acidic Amino Acids; Active Sites; Address; Affect; Alanine; Antiviral Agents; Aspartic Acid; Bacteriophages; Biochemical; CD4 Positive T Lymphocytes; Cell Cycle; Cells; DNA; Dendritic Cells; Development; Eukaryotic Cell; Exhibits; Exonuclease; Genetic Transcription; HIV-1; HIV-2; Hour; Human; Immune response; Immune system; In Vitro; Infection; Infection prevention; Mass Spectrum Analysis; Nature; Nucleotides; Phenotype; Phosphorylation; Phosphotransferases; Positioning Attribute; Property; Proteins; RNA; Regulation; Rest; Reverse Transcription; Role; SIV; Subfamily lentivirinae; T-Lymphocyte; Testing; Threonine; Vaccines; Variant; Viral; Virus; Virus Diseases; Work; blocking factor; deoxyguanosine triphosphate; in vivo; interest; macrophage; mutant; novel; particle; prevent; protein folding; public health relevance; tripolyphosphate

DESCRIPTION: Expression of the recently discovered human restriction factor SAMHD1 is responsible for the infection block imposed to lentiviruses such as HIV-1, HIV-2 and SIVmac by primary macrophages, dendritic cells and resting CD4+ T-cells. SAMHD1 blocks lentiviral infection by preventing the occurrence of reverse transcription. The viral accessory protein Vpx, contained in SIVmac and HIV-2 particles, overcomes the SAMHD1 reverse transcription block by inducing SAMHD1 degradation. SAMHD1 is a dGTP-regulated deoxynucleotide triphosphohydrolase that decreases the cellular levels of triphosphodeoxynucleotides (dNTPs). The dramatic decrease in dNTP levels in macrophages, dendritic cells and CD4+ resting T cells correlates with the inability of lentiviruses to undergo reverse transcription; therefore, SAMHD1 prevents lentiviral reverse transcription by depletion of dNTP levels. Interestingly, cycling and non-cycling cells express SAMHD1; however, SAMHD1's antiviral activity is only observed in non-cycling cells. Our preliminary findings correlate the lentiviral restriction phenotype observed in non-cycling cells with the phosphorylation state of SAMHD1.These results strongly suggested that phosphorylation regulates the antiviral activity of SAMHD1; therefore, this proposal will test the hypothesis that phosphorylation of SAMHD1 induces a conformational change that closes the active site of SAMHD1 domain resulting in an enzymatically and antivirally inactive SAMHD1 protein. The following specific aims will be used to address this hypothesis. Aim1 will explore the role of SAMHD1 phosphorylation in retroviral restriction. For this purpose, we will study restriction of SAMHD1 proteins where the phosphorylatable residues are replaced by either a phosphomimetic or non-phosphorylatable residue. This aim will also explore the nature of the kinase involved in the phosphorylation of SAMHD1. Aim 2 will explore the ability of Vpx to modulate SAMHD1 antiviral and enzymatic activities before SAMHD1 degradation. Aim 3 will explore the regulation of the antiviral and enzymatic activity of SAMHD1. Specifically, this aim will test the notion that SAMHD1 is regulated by a ball-and-chain mechanism. Overall, this proposal will establish phosphorylation as a new framework for understanding the antiviral properties of SAMHD1. Understanding the regulation of SAMHD1 is instrumental for the development of novel anti-HIV-1 vaccine strategies since overcoming SAMHD1 increases the adaptive immune response during infection of dendritic cells and macrophages. In addition, macrophages represent one of the most resilient HIV-1 reservoirs, so understanding the regulation of SAMHD1 antiviral properties could provide novel insides for the elimination of HIV-1 reservoirs.

描述：最近发现的人类限制因子SAMHD1的表达是导致原代巨噬细胞、树突状细胞和静止的CD4+T细胞对慢病毒如HIV-1、HIV-2和SIVmac的感染阻断的原因。SAMHD1通过阻止反转录的发生来阻止慢病毒的感染。病毒辅助蛋白VPX包含在SIVmac和HIV-2颗粒中，通过诱导SAMHD1降解来克服SAMHD1反转录障碍。SAMHD1是一种受dGTP调控的脱氧核苷酸水解酶，可降低细胞内三磷酸脱氧核苷酸(DNTPs)的水平。巨噬细胞、树突状细胞和CD4+静息T细胞中dNTP水平的急剧下降与慢病毒无法进行逆转录有关；因此，SAMHD1通过耗尽dNTP水平来阻止慢病毒的逆转录。有趣的是，周期细胞和非周期细胞都表达SAMHD1；然而，SAMHD1‘S抗病毒活性只在非周期细胞中观察到。我们的初步发现与观察到的慢病毒限制表型相关 在具有SAMHD1磷酸化状态的非周期细胞中，这些结果强烈地表明，磷酸化调节SAMHD1的抗病毒活性；因此，这一提议将测试 该假说认为，SAMHD1的磷酸化导致构象改变，从而关闭SAMHD1结构域的活性部位，导致SAMHD1蛋白在酶和抗病毒方面无效。以下具体目标将被用来解决这一假设。AIM1将探讨SAMHD1磷酸化在逆转录病毒限制性内切酶中的作用。为此，我们将研究SAMHD1蛋白的限制，其中可磷酸化残基被拟磷化残基或非可磷酸化残基取代。这一目标还将探索参与SAMHD1磷酸化的激酶的性质。目的2探讨VPX在SAMHD1降解前对SAMHD1抗病毒和酶活性的调节能力。目的3探讨SAMHD1的抗病毒活性和酶活性的调节。具体地说，这一目标将检验SAMHD1是由一种球和链机制监管的想法。总体而言，这项提议将把磷酸化作为理解SAMHD1抗病毒特性的新框架。了解SAMHD1的调控有助于开发新的抗HIV-1疫苗策略，因为克服SAMHD1可以增加树突状细胞和巨噬细胞感染期间的适应性免疫反应。此外，巨噬细胞代表最具弹性的HIV-1宿主之一，因此了解SAMHD1抗病毒特性的调节可以为消除HIV-1宿主提供新的内部机制。