Identification of Cellular Proteins Interacting with the Retroviral Restriction Factor SAMHD1
Identification of Cellular Proteins Interacting with the Retroviral Restriction Factor SAMHD1
复制标题
DOI：
10.1128/jvi.00155-14
复制
发表时间：
2014-05-01
影响因子：
5.4
通讯作者：
Wu, Li
中科院分区：
文献类型：
--
作者：
Gelais, Corine St.;de Silva, Suresh;Wu, Li
人类和小鼠 SAMHD1 蛋白通过降低细胞内脱氧核苷三磷酸 (dNTP) 浓度来阻断非循环人类单核细胞中的人类免疫缺陷病毒 1 型 (HIV-1) 感染。人 SAMHD1 在苏氨酸 592 (T592) 处被细胞周期蛋白依赖性激酶 1 (CDK1) 和细胞周期蛋白 A2 磷酸化会损害其 HIV-1 限制活性，但不会损害 dNTP 水解酶活性，表明 dNTP 耗竭并不是 SAMHD1 介导的 HIV-1 限制的唯一机制。利用免疫共沉淀和质谱法，我们鉴定并验证了另外两种与人 SAMHD1 相互作用的宿主蛋白，即细胞周期蛋白依赖性激酶 2 (CDK2) 和 S 期激酶相关蛋白 2 (SKP2)。我们观察到小鼠 SAMHD1 与细胞周期蛋白 A2、细胞周期蛋白 B1、CDK1 和 CDK2 特异性相互作用。鉴于这些 SAMHD1 相互作用蛋白在细胞周期进程中的作用，我们研究了这些宿主蛋白通过单核细胞分化和 CD4(+) T 细胞激活的调节，并检查了它们对人 SAMHD1 T592 磷酸化的影响。我们的结果表明，原代单核细胞分化和 CD4(+) T 细胞激活调节这些 SAMHD1 相互作用蛋白的表达。此外，我们的结果表明，除了CDK1和细胞周期蛋白A2之外，CDK2还磷酸化人SAMHD1的T592，从而调节其HIV-1限制功能。
Human and mouse SAMHD1 proteins block human immunodeficiency virus type 1 (HIV-1) infection in noncycling human monocytic cells by reducing the intracellular deoxynucleoside triphosphate (dNTP) concentrations. Phosphorylation of human SAMHD1 at threonine 592 (T592) by cyclin-dependent kinase 1 (CDK1) and cyclin A2 impairs its HIV-1 restriction activity, but not the dNTP hydrolase activity, suggesting that dNTP depletion is not the sole mechanism of SAMHD1-mediated HIV-1 restriction. Using coimmunoprecipitation and mass spectrometry, we identified and validated two additional host proteins interacting with human SAMHD1, namely, cyclin-dependent kinase 2 (CDK2) and S-phase kinase-associated protein 2 (SKP2). We observed that mouse SAMHD1 specifically interacted with cyclin A2, cyclin B1, CDK1, and CDK2. Given the role of these SAMHD1-interacting proteins in cell cycle progression, we investigated the regulation of these host proteins by monocyte differentiation and activation of CD4(+) T cells and examined their effect on the phosphorylation of human SAMHD1 at T592. Our results indicate that primary monocyte differentiation and CD4(+) T-cell activation regulate the expression of these SAMHD1-interacting proteins. Furthermore, our results suggest that, in addition to CDK1 and cyclin A2, CDK2 phosphorylates T592 of human SAMHD1 and thereby regulates its HIV-1 restriction function.