We have previously demonstrated that binding of HIV-1 to the chemokine coreceptor, CXCR4, on resting CD4 T cells activates an actin-depolymerizing factor cofilin to promote the cortical actin dynamic critical for HIV latent infection . The LIM domain kinase 1 (LIMK1) directly phosphorylates cofilin and regulates the actin cytoskeleton. Here, we investigated the role of LIMK1 in HIV-1 infection of resting CD4 T cells and found that HIV-1 infection triggered a rapid, transient activation of LIMK1. We also used siRNA knockdown to inhibit LIMK1 activity and found that knockdown of LIMK1 caused a decrease of F-actin and T cell chemotaxis. LIMK1 also had dichotomous effects on the chemokine coreceptor CXCR4 cycling (Figure 1) and viral DNA synthesis (Figure 2). Our findings are consistent with a model suggesting a multi-functional role of the cortical actin in mediating chemokine coreceptor density, HIV-1 DNA synthesis and intracellular migration.
Department of Molecular and Microbiology, George Mason University, Manassas, USA
Yoder A, Yu D, Dong L, Iyer SR, Xu X, Kelly J, Liu J, Wang W, Vorster PJ, Agulto L, Stephany DA, Cooper JN, Marsh JW, Wu Y: HIV envelope-CXCR4 signaling activates cofilin to overcome cortical actin restriction in resting CD4 T cells. Cell. 134: 782-92. 10.1016/j.cell.2008.06.036.Google Scholar