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的表达是由原代巨噬细胞，树突状细胞和静息CD4+ T细胞施加的感染阻滞，例如HIV-1，HIV-2和SIVMAC。 SAMHD1通过防止发生逆转录的发生来阻止慢病毒感染。 SIVMAC和HIV-2颗粒中包含的病毒辅助蛋白VPX通过诱导SAMHD1降解来克服SAMHD1逆转录块。 SAMHD1是DGTP调节的脱氧核苷酸三磷酶，可降低三磷脱氧核苷酸（DNTPS）的细胞水平。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的无能相关。因此，SAMHD1通过DNTP水平的耗竭来防止慢病毒逆转录。有趣的是，循环和非循环细胞表达SAMHD1；但是，仅在非循环细胞中观察到SAMHD1的抗病毒活性。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的磷酸化状态的非周期细胞中。这些结果强烈表明磷酸化调节SAMHD1的抗病毒活性。因此，该建议将测试 SAMHD1的磷酸化诱导构象变化的假说，它关闭了SAMHD1结构域的活性位点，从而导致酶促和抗病毒性无活性SAMHD1蛋白。以下特定目标将用于解决这一假设。 AIM1将探索SAMHD1磷酸化在逆转录病毒限制中的作用。为此，我们将研究对SAMHD1蛋白的限制，其中可磷酸化的残基被磷酸化或非磷酸化残基取代。该目标还将探索与SAMHD1磷酸化有关的激酶的性质。 AIM 2将探讨VPX在SAMHD1降解之前调节SAMHD1抗病毒和酶促活性的能力。 AIM 3将探索SAMHD1抗病毒和酶活性的调节。具体而言，该目标将测试SAMHD1受球形机制调节的观念。总体而言，该提案将建立磷酸化作为理解SAMHD1抗病毒特性的新框架。了解SAMHD1的调节对新型抗HIV-1疫苗策略的发展至关重要，因为克服SAMHD1会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，巨噬细胞代表了最有弹性的HIV-1储层之一，因此了解SAMHD1抗病毒特性的调节可以为消除HIV-1储层提供新颖的内部。