Division of Infectious Diseases, Advanced Clinical Research Center, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
Biochem Biophys Res Commun. 2010 Mar 19;393(4):598-602. doi: 10.1016/j.bbrc.2010.02.021. Epub 2010 Feb 10.
The dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and DC-SIGN-related (DC-SIGNR) molecules on the cell surface are known to enhance human immunodeficiency virus type 1 (HIV-1) infection by capturing the virions and transmitting them to CD4+ T-cell, a process termed trans-infection. The neck region and carbohydrate recognition domain of the two proteins are important for efficient binding to the HIV-1 envelope protein. DC-SIGNR is polymorphic in Exons 4 and 5 that encode the neck region and carbohydrate recognition domain, respectively; the former contains a variable number of tandem repeats, and the latter the SNP (rs2277998). Since it remains unclear whether the DC-SIGNR polymorphism is related to the risk of HIV-1 infection, we tested possible effects of the polymorphism on HIV-1 trans-infection efficiency, by constructing six kinds of cDNAs encoding DC-SIGNR variants with various numbers of repeat units and various SNP. We were able to express the variants on the surface of Raji cells, a human B cell line. Flow cytometry showed that all the tested DC-SIGNR molecules were efficiently expressed on the cell surface at various levels; the assay for HIV trans-infection efficacy showed that all the tested variants had that activity with different efficacy levels. We found a correlation between the HIV trans-infection efficiency and the mean fluorescent intensity of DC-SIGNR expression (R(2)=0.95). Thus, our results suggest that the variation of the tested DC-SIGNR genotypes affects the efficacy of trans-infection by affecting the amounts of the protein expressed on the cell surface.
树突状细胞特异性细胞间黏附分子-3 捕获非整合素（DC-SIGN）和 DC-SIGN 相关（DC-SIGNR）分子在细胞表面，已知通过捕获病毒颗粒并将其传递给 CD4+T 细胞来增强人类免疫缺陷病毒 1 型（HIV-1）的感染，这个过程称为转染。这两种蛋白质的颈部区域和碳水化合物识别域对于与 HIV-1 包膜蛋白的有效结合很重要。DC-SIGNR 在分别编码颈部区域和碳水化合物识别域的外显子 4 和 5 中是多态的；前者包含可变数量的串联重复，后者是 SNP(rs2277998)。由于尚不清楚 DC-SIGNR 多态性是否与 HIV-1 感染的风险有关，我们通过构建编码具有不同重复单元和不同 SNP 的 DC-SIGNR 变体的六种 cDNA，来测试该多态性对 HIV-1 转染效率的可能影响。我们能够在 Raji 细胞（一种人类 B 细胞系）表面表达这些变体。流式细胞术显示，所有测试的 DC-SIGNR 分子都以不同的水平在细胞表面高效表达；HIV 转染效率的测定表明，所有测试的变体都具有不同的功效水平的转染活性。我们发现 HIV 转染效率与 DC-SIGNR 表达的平均荧光强度之间存在相关性（R2=0.95）。因此，我们的结果表明，所测试的 DC-SIGNR 基因型的变异通过影响细胞表面表达的蛋白量来影响转染效率。
