Mariani R, Wong S, Mulder L C, Wilkinson D A, Reinhart A L, LaRosa G, Nibbs R, O'Brien T R, Michael N L, Connor R I, Macdonald M, Busch M, Koup R A, Landau N R
Aaron Diamond AIDS Research Center, The Rockefeller University, New York, New York 10016, USA.
J Virol. 1999 Mar;73(3):2450-9. doi: 10.1128/JVI.73.3.2450-2459.1999.
A polymorphism in the gene encoding CCR2 is associated with a delay in progression to AIDS in human immunodeficiency virus (HIV)-infected individuals. The polymorphism, CCR2-64I, changes valine 64 of CCR2 to isoleucine. However, it is not clear whether the effect on AIDS progression results from the amino acid change or whether the polymorphism marks a genetically linked, yet unidentified mutation that mediates the effect. Because the gene encoding CCR5, the major coreceptor for HIV type 1 primary isolates, lies 15 kb 3' to CCR2, linked mutations in the CCR5 promoter or other regulatory sequences could explain the association of CCR2-64I with slowed AIDS pathogenesis. Here, we show that CCR2-64I is efficiently expressed on the cell surface but does not have dominant negative activity on CCR5 coreceptor function. A panel of peripheral blood mononuclear cells (PBMC) from uninfected donors representing the various CCR5/CCR2 genotypes was assembled. Activated primary CD4(+) T cells of CCR2 64I/64I donors expressed cell surface CCR5 at levels comparable to those of CCR2 +/+ donors. A slight reduction in CCR5 expression was noted, although this was not statistically significant. CCR5 and CCR2 mRNA levels were nearly identical for each of the donor PBMC, regardless of genotype. Cell surface CCR5 and CCR2 levels were more variable than mRNA transcript levels, suggesting that an alternative mechanism may influence CCR5 cell surface levels. CCR2-64I is linked to the CCR5 promoter polymorphisms 208G, 303A, 627C, and 676A; however, in transfected promoter reporter constructs, these did not affect transcriptional activity. Taken together, these findings suggest that CCR2-64I does not act by influencing CCR5 transcription or mRNA levels.
编码CCR2的基因中的一种多态性与人类免疫缺陷病毒（HIV）感染个体中艾滋病进展延迟相关。这种多态性CCR2 - 64I将CCR2的缬氨酸64变为异亮氨酸。然而，尚不清楚对艾滋病进展的影响是由氨基酸变化导致的，还是该多态性标记了一个介导该效应的基因连锁但尚未鉴定的突变。因为编码HIV - 1主要分离株主要共受体CCR5的基因位于CCR2下游15 kb处，CCR5启动子或其他调控序列中的连锁突变可能解释CCR2 - 64I与艾滋病发病机制减缓之间的关联。在此，我们表明CCR2 - 64I在细胞表面有效表达，但对CCR5共受体功能没有显性负性活性。我们收集了一组来自未感染供体的外周血单核细胞（PBMC），这些供体代表了各种CCR5/CCR2基因型。CCR2 64I/64I供体的活化原代CD4(+) T细胞表达的细胞表面CCR5水平与CCR2 +/+供体相当。虽然观察到CCR5表达略有降低，但这在统计学上并不显著。无论基因型如何，每个供体PBMC的CCR5和CCR2 mRNA水平几乎相同。细胞表面CCR5和CCR2水平比mRNA转录水平更具变异性，这表明一种替代机制可能影响CCR5细胞表面水平。CCR2 - 64I与CCR5启动子多态性208G、303A、627C和676A连锁；然而，在转染的启动子报告构建体中，这些多态性并不影响转录活性。综上所述，这些发现表明CCR2 - 64I并非通过影响CCR5转录或mRNA水平发挥作用。
