Mueller Anja, Strange Philip G
School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading, UK.
Eur J Biochem. 2004 Jan;271(2):243-52. doi: 10.1046/j.1432-1033.2003.03918.x.
CCR5 is a G protein-coupled receptor that binds several natural chemokines but it is also a coreceptor for the entry of M tropic strains of HIV-1 into cells. Levels of CCR5 on the cell surface are important for the rate of HIV-1 infection and are determined by a number of factors including the rates of CCR5 internalization and recycling. Here we investigated the involvement of the actin cytoskeleton in the control of ligand-induced internalization and recycling of CCR5. Cytochalasin D, an actin depolymerizing agent, inhibited chemokine-induced internalization of CCR5 and recycling of the receptor in stably transfected CHO cells and in the monocytic cell line, THP-1. CCR5 internalization and recycling were inhibited by Toxin B and C(3) exoenzyme treatment in CHO and THP-1 cells, confirming activation of members of the RhoGTPase family by CCR5. The specific Rho kinase inhibitor Y27632, however, had no effect on CCR5 internalization or recycling. Ligand-induced activation of CCR5 leads to Rho kinase-dependent formation of focal adhesion complexes. These data indicate that CCR5 internalization and recycling are regulated by actin polymerization and activation of small G proteins in a Rho-dependent manner.
CCR5是一种G蛋白偶联受体，可结合多种天然趋化因子，但它也是M嗜性HIV-1毒株进入细胞的共受体。细胞表面CCR5的水平对HIV-1感染率很重要，并且由许多因素决定，包括CCR5内化和再循环的速率。在这里，我们研究了肌动蛋白细胞骨架在CCR5配体诱导的内化和再循环控制中的作用。细胞松弛素D是一种肌动蛋白解聚剂，它抑制趋化因子诱导的CCR5内化以及稳定转染的CHO细胞和单核细胞系THP-1中受体的再循环。在CHO和THP-1细胞中，毒素B和C(3)外切酶处理抑制了CCR5的内化和再循环，证实了CCR5对RhoGTPase家族成员的激活作用。然而，特异性Rho激酶抑制剂Y27632对CCR5的内化或再循环没有影响。配体诱导的CCR5激活导致粘着斑复合物的Rho激酶依赖性形成。这些数据表明，CCR5的内化和再循环受肌动蛋白聚合和小G蛋白以Rho依赖性方式激活的调节。
