Host Cell Factors and AIDS Pathogenesis

宿主细胞因素与艾滋病发病机制

• 批准号: 6726154
• 负责人: GHALIB ABBAS ALKHATIB
• 金额: $ 33.53万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-15 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6726154
• 关键词: AIDS; cell line; cytokine receptors; frameshift mutation; genetic polymorphism; genetic susceptibility; human immunodeficiency virus 1; human tissue; immunoprecipitation; laboratory mouse; laboratory rabbit; lymphocyte; monocyte; open reading frames; pathologic process; receptor expression; virus genetics; virus infection mechanism; virus receptors; yeast two hybrid system

Human immunodeficiency virus type 1 (HIV-1) requires CD4 and a coreceptor for entry, into susceptible host cells. The chemokine receptors CXCR4 and CCR5 are the major coreceptors used by T cell line-tropic (X4) and macrophage-tropic (R5) HIV-1 isolates. A naturally occurring frame-shift mutation caused by a 32 base pair deletion (delta32) in the human CCR5 gene resulted in a truncated protein that does not function as a coreceptor. Relative to the general population, CCR5delta32 homozygotes (-/-) are rarely found among HIV-1 infected individuals. In addition, HIV-1 infected CCR5delta32 heterozygotes (+/-) progress more slowly to AIDS than individuals lacking this allele indicating that even one delta32 allele confers some resistance. We have found that expression of full-length delta32 protein in human cell lines or normal human peripheral blood mononuclear cells (PBMCs) can specifically downmodulate endogenous CXCR4 and inhibit X4 infection. We have demonstrated efficient co- localization of delta32 and either CXCR4 or CCR5. Truncation of the delta32 C-terminus resulted in the loss of CXCR4 downmodulation activity. Furthermore, we showed that PBMCs from several (-/-) individuals express lower CXCR4 levels in comparison to wild-type CCR5 (+/+) PBMCs. We hypothesize that one mechanism of resistance to HIV-1 is caused by the unique activity of the delta32 protein. Using delta32-specific antibodies, we have shown that native delta32 protein was expressed in (-/-) PBMCs isolated from exposed/uninfected [1]but was absent in an infected (-/-) individuals [2], indicating a critical role for the delta32 protein in resistance to HIV-1 infection. The overall purpose of this proposal is to determine the mechanism(s) that underlies the observed more broad protective effect by the naturally occurring delta32 protein. The following specific aims are based on preliminary data generated in my laboratory: 1. Analyze how delta32 impairs functional expression of CCR5 and CXCR4. 2. Analyze the mechanism of failure of delta32 protective effect in an infected delta32 homozygous individual. 3. Determine the structural determinants involved in delta32 activity.

人类免疫缺陷病毒1型（HIV-1）需要CD4和进入易感宿主细胞的共核能。 趋化因子受体CXCR4和CCR5是T细胞线 - 循环（X4）和巨噬细胞 - 循环（R5）HIV-1分离株使用的主要共感染物。 由人CCR5基因中的32碱基对缺失（Delta32）引起的天然型换移突变导致截短的蛋白质，该蛋白质不起作用。相对于普通人群，在HIV-1感染个体中很少发现CCR5DELTA32纯合子（ - / - ）。 此外，HIV-1感染的CCR5DELTA32杂合子（+/-）比缺乏该等位基因的个体更慢，表明即使有一个Delta32等位基因也具有某种抗性。 我们发现，在人细胞系或正常人外周血单核细胞（PBMC）中，全长Delta32蛋白的表达可以特异性下调内源性CXCR4并抑制X4感染。 我们已经证明了Delta32和CXCR4或CCR5的有效合作。 Delta32 C末端的截断导致CXCR4下调活性的丧失。 此外，我们表明，与野生型CCR5（+/+）PBMC相比，来自几个（ - / - ）个体的PBMC表示较低的CXCR4水平。 我们假设一种对HIV-1的抗性机制是由Delta32蛋白的独特活性引起的。 使用DELTA32特异性抗体，我们表明，天然的Delta32蛋白在（ - / - ）PBMC中表达在暴露/未感染的[1]中，但在受感染的（ - - ）个体中不存在[2]，这表明DELTA32蛋白在抗HIV-1的感染中的关键作用是至关重要的。 该提案的总体目的是确定由天然存在的Delta32蛋白观察到的更广泛保护作用的机制。以下具体目的基于我的实验室中生成的初步数据：1。分析Delta32如何损害CCR5和CXCR4的功能表达。 2。分析Delta32防护作用在感染的Delta32纯合子中的失败机理。 3。确定Delta32活性涉及的结构决定因素。