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Role of Tat and SIRT1 in the T-cell Hyperactivation Syndrome Induced by HIV-1

Tat 和 SIRT1 在 HIV-1 诱导的 T 细胞过度激活综合征中的作用

基本信息

批准号：
8602796
负责人：
Melanie Maria Ott
金额：
$ 47.27万
依托单位：
J. DAVID GLADSTONE INSTITUTES
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-01-01 至 2015-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8602796
关键词：
AIDS/HIV problem Acquired Immunodeficiency Syndrome Address Aging Antibodies Antiviral Agents Apoptotic Attenuated Binding Blood Circulation CD28 gene CD3 Antigens CD4 Positive T Lymphocytes CD8B1 gene Cell Culture Techniques Cell Death Cell Line Cells Chronic Consensus Coupled Cytomegalovirus Data Deacetylase Deacetylation Development Disease Disease Progression Engineering Equilibrium Flow Cytometry Gene Expression Generations Genes Green Fluorescent Proteins HIV HIV Infections HIV-1 HLA-DR Antigens Health Helper-Inducer T-Lymphocyte Highly Active Antiretroviral Therapy Histone Deacetylase Human Human Herpesvirus 4 Immune Immune response Immune system Individual Infection Infectious Agent Inflammation Inflammatory Interleukin-1 Interleukin-2 Interleukin-6 Interphase Cell Investigation Laboratories Lentivirus Vector Link Longevity Measures Mediating Microbe Modeling Molecular Molecular Biology Molecular Profiling Nature Nicotinamide adenine dinucleotide Outcome Participant Patients Peripheral Phenotype Plasma Play Population Process Production Proteins Regulation Regulatory T-Lymphocyte Reporting Research Role SIV Shapes Signal Transduction Subfamily lentivirinae Surface Symptoms Syndrome T-Cell Activation T-Lymphocyte TNF gene Testing Therapeutic Trans-Activators Viral Virus Diseases cytokine design genetic regulatory protein genome-wide immune activation immune function insight interest lymph nodes microbial novel novel strategies novel therapeutic intervention p300/CBP-Associated Factor p65 programs receptor expression research study response small hairpin RNA small molecule tat Protein transcription factor

项目摘要

DESCRIPTION (provided by applicant): Symptoms of T-cell hyperactivation shape the course and outcome of HIV-1 infection, but the molecular mechanism(s) underlying this chronic immune activation are not well understood. We have identified a novel mechanism by which the HIV-1 Tat protein leads to chronic immune activation. We find that Tat hyperactivates T cells by blocking the deacetylase activity of SIRT1 (Kwon et al, Cell Host Microbe, 2008). SIRT1 is a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylase and an important regulator of the transcription factor NF-B. Tat directly interacts with the deacetylase domain of SIRT1 and blocks the ability of SIRT1 to deacetylate the RelA/p65 subunit of NF-B. Because acetylated p65 is more active as a transcription factor, Tat hyperactivates the expression of NF-B-responsive genes, such as interleukin-2 (IL-2). These results support a model where the normal function of SIRT1 as a negative regulator of T-cell activation is suppressed by Tat during HIV infection. We propose to define the novel role of SIRT1 as a regulator of immune activation in HIV-infected T cells. We have new and unpublished findings that link the SIRT1 deacetylase activity with immune-suppressive functions of regulatory T cells (Tregs). Special focus of this proposal lies therefore on the characterization of the function of Tat and SIRT1 in Tregs and on the identification of novel SIRT1 substrates in effector and regulatory T cells populations. The importance of these studies is highlighted by their possible impact on the development of novel therapeutic interventions. Potent small molecule activators of SIRT1 have recently become available with great promise in diseases associated with aging (Milne et al, Nature, 2007). We will use these activators to test the hypothesis that activating the suppressor function of SIRT1 will counterbalance the immune stimulatory function of Tat and may represent a novel strategy to treat chronic immune activation in HIV-infected patients. Our specific aims are: 1) we will study the role of SIRT1 in HIV-infected T cells. We will infect Jurkat T cell lines in which SIRT1 expression is down regulated via shRNAs with a GFP-tagged infectious clone of HIV-1 and study intracellular IL-2 production in infected (GFP+) and uninfected (GFP-) cells in response to activation with anti-CD3 and CD28 antibodies. We will also infect primary CD4+ T cell cultures with HIV-1 and test whether treatment with SIRT1 activators can reverse hyperstimulation of IL-2 production. 2) We will identify novel targets of the SIRT1 deacetylase activity in infected T cells. We have preliminary evidence that Tat by inhibiting SIRT1 induces hyperacetylation of several SIRT1 targets including proapoptotic factors p53 and Foxo3A. Since both factors are important regulators of T-cell death during HIV infection, we will study how Tat manipulates the transcriptional activities and proapoptotic functions of both factors. We will also perform genome-wide expression profiling and identify gene programs that are modulated by Tat expression or SIRT1 knockdown. 3) We will examine how the SIRT1/Tat interaction influences the development and function of Tregs. We have preliminary results showing that SIRT1 promotes TGF--induced Treg development and is involved in deacetylation of the transcription factor FoxP3. We propose to study how SIRT1 regulates expression and function of FoxP3 in Tregs and will characterize how Tat expression during HIV infection can interfere with this process. These studies will bring novel insight into the molecular biology of HIV-induced immune activation and identify yet undefined mechanisms of HDAC-mediated control of the immune response.

描述（由申请人提供）：T细胞过度活化的症状塑造了HIV-1感染的过程和结果，但这种慢性免疫活化的分子机制尚未得到很好的理解。我们已经确定了HIV-1达特蛋白导致慢性免疫激活的一种新机制。我们发现，达特通过阻断SIRT 1的脱乙酰酶活性来过度活化T细胞（Kwon等人，Cell Host Microbe，2008）。SIRT 1是一种烟酰胺腺嘌呤二核苷酸（NAD+）依赖性组蛋白脱乙酰酶，是转录因子NF-B的重要调节因子。达特直接与SIRT 1的脱乙酰酶结构域相互作用，并阻断SIRT 1使NF-B的RelA/p65亚基脱乙酰化的能力。因为乙酰化的p65作为转录因子更有活性，所以达特过度激活NF-B应答基因的表达，例如白细胞介素-2（IL-2）。这些结果支持这样一种模型，其中SIRT 1作为T细胞活化的负调节剂的正常功能在HIV感染期间被达特抑制。我们建议定义SIRT 1作为HIV感染T细胞免疫激活调节因子的新作用。我们有新的未发表的发现，将SIRT 1脱乙酰酶活性与调节性T细胞（TCFs）的免疫抑制功能联系起来。因此，该建议的特别重点在于表征达特和SIRT 1在Tcells中的功能，以及鉴定效应和调节T细胞群体中的新型SIRT 1底物。这些研究的重要性突出了它们对新的治疗干预措施的发展可能产生的影响。SIRT 1的有效小分子活化剂最近已变得可获得，在与衰老相关的疾病中具有很大的前景（Milne等人，Nature，2007）。我们将使用这些激活剂来验证这一假设，即激活SIRT 1的抑制功能将抵消达特的免疫刺激功能，并可能代表一种治疗HIV感染患者慢性免疫激活的新策略。我们的具体目标是：1）我们将研究SIRT 1在HIV感染的T细胞中的作用。我们将感染Jurkat T细胞系，其中SIRT 1表达通过shRNA与GFP标记的HIV-1感染性克隆下调，并研究感染（GFP+）和未感染（GFP-）细胞中响应抗CD 3和CD 28抗体激活的细胞内IL-2产生。我们还将用HIV-1感染原代CD 4 + T细胞培养物，并测试SIRT 1激活剂治疗是否可以逆转IL-2产生的过度刺激。2)我们将确定新的目标SIRT 1脱乙酰酶活性在感染的T细胞。我们有初步的证据表明，达特通过抑制SIRT 1诱导几个SIRT 1靶点的过度乙酰化，包括促凋亡因子p53和Foxo 3A。由于这两个因素是重要的调节T细胞死亡在HIV感染，我们将研究如何达特操纵转录活动和促凋亡功能的两个因素。我们还将进行全基因组表达谱分析，并确定由达特表达或SIRT 1敲低调控的基因程序。3)我们将研究SIRT 1/达特相互作用如何影响TTRO的发育和功能。我们有初步的结果表明，SIRT 1促进TGF-β诱导的Treg的发展，并参与转录因子FoxP 3的脱乙酰化。我们建议研究SIRT 1如何调节FoxP 3在Tcb中的表达和功能，并将表征HIV感染过程中达特的表达如何干扰这一过程。这些研究将为HIV诱导的免疫激活的分子生物学带来新的见解，并确定HDAC介导的免疫反应控制的尚未确定的机制。