NHERF1 regulates gp120‐induced internalization and signaling by CCR5, and HIV‐1 production

Abstract

The scaffolding protein Na 1 /H1 exchanger regulator factor 1 (NHERF1) plays an important role in the trafficking of G protein-coupled receptors. We previously demonstrated that NHERF1 is involved in chemokine receptor CCR5 homodimer internalization and signal transduction. Given the importance of CCR5 internalization during HIV-1 infection, we evaluated NHERF1's contribution in HIV-1 infection. We challenged human osteosarcoma cells coexpressing CD4 and CCR5 cells expressing either NHERF1 fragment domains or WT NHERF1 with an HIV-1 strain to examine the effects of NHERF1 on HIV-1 entry and replication. WT NHERF1 potentiates HIV-1 envelope gp120-induced CCR5 internalization, and promotes the replication of HIV-1. In order to better understand how NHERF1 affects signal transduction, different domains of NHERF1 were overexpressed in cells to analyze their effect on the different signaling pathways. Here, we show that NHERF1 can associate with CCR5, and promote activation of the gp120-induced MAPK/ERK, focal adhesion kinase and RhoA (Ras homolog gene family member A) signaling pathways. NHERF1 overexpression also increases HIV-1 host cell migration triggered by gp120 via focal adhesion kinase (FAK) signaling. Finally, NHERF1 enhanced actin filament rearrangement in host cells, an important step in post-entry HIV-1 replication events. While postsynaptic density 95/disk-large/zonula occludens 2 (PDZ2) appears to be the major contributor in those events, other domains also participate in the regulation of gp120-induced signaling pathways. Altogether, our results suggest a very important role of the scaffold NHERF1 in the regulation of HIV-1 entry and replication.

Altered lipid concentrations of liver, heart and plasma but not brain in HIV-1 transgenic rats

“…Because HIV-1 Tg rats lack these replicative elements, this study demonstrates that non-replicative viral elements also profoundly change tissue lipid concentrations as well as membrane phospholipid composition. This is in agreement with studies that reported that the gp120, Env and nef non-replicative elements of the HIV-1 protein interact with plasma membranes, cause localized changes in lipid composition and disrupt cell protein trafficking and signaling [26, 48, 49, 28, 29], consistent with in vitro evidence of increased N-methyl-D-aspartate receptor clustering in lipid microdomains caused by the gp-120 element of the virus [50]. Identifying and targeting non-replicative viral elements that cause membrane lipid disruptions may improve the clinical efficacy of antiretroviral drugs, particularly those that interfere with the membrane phospholipid clustering assembly of the virus and its entry into the host cell [51].…”

HIV-Associated Disruption of Tight and Adherens Junctions of Oral Epithelial Cells Facilitates HSV-1 Infection and Spread

“…Binding of HIV gp120 to chemokine receptors CXCR4 and CCR5 in lymphocytes and macrophages also leads to induction of MAPK [64], [65], [66], [67]. We have shown that polarized oral epithelial cells express to β1 and ϖ integrins, and CCR5 and CXCR4 [44], [46], [68], indicating availability of HIV tat and gp120 receptors in oral epithelium.…”

PDZ Protein Regulation of G Protein–Coupled Receptor Trafficking and Signaling Pathways

“…NHERF1 enhances chemokine (C-C motif) receptor 5 (CCR5) endocytosis and b-arrestin1 recruitment, thereby promoting the activation of ERK, Rho, and focal adhesion kinase signaling pathways, as well as potentially contributes to CCR5-mediated HIV-1 entry (Hammad et al, 2010;Kuang et al, 2012). NHERF1 overexpression also rescues the endocytosis of an internalization-defective platelet-activating factor receptor and antagonizes platelet-activating factor receptor-mediated inositol phosphate formation .…”

“…CCR5 functions as a coreceptor for HIV-1 viral entry into mammalian cells by functioning as a cofactor for the entry of the virus (Henrich and Kuritzkes, 2013). NHERF1 interactions with CCR5 function to enhance actin filament rearrangement of host cells, a function that is essential to allow postcell entry HIV-1 replication (Hammad et al, 2010;Kuang et al, 2012). PDZK1 interactions with hIPR selectively facilitate hIPRdependent activation of endothelial migration and vascular angiogenesis in vitro (Turner et al, 2011).…”