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. 1999 Aug 15;94(4):1165-73.

A Synthetic Peptide Derived From Human Immunodeficiency Virus Type 1 gp120 Downregulates the Expression and Function of Chemokine Receptors CCR5 and CXCR4 in Monocytes by Activating the 7-transmembrane G-protein-coupled Receptor FPRL1/LXA4R

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  • PMID: 10438703

A Synthetic Peptide Derived From Human Immunodeficiency Virus Type 1 gp120 Downregulates the Expression and Function of Chemokine Receptors CCR5 and CXCR4 in Monocytes by Activating the 7-transmembrane G-protein-coupled Receptor FPRL1/LXA4R

X Deng et al. Blood. .

Abstract

Because envelope gp120 of various strains of human immunodeficiency virus type 1 (HIV-1) downregulates the expression and function of a variety of chemoattractant receptors through a process of heterologous desensitization, we investigated whether epitopes derived from gp120 could mimic the effect. A synthetic peptide domain, designated F peptide, corresponding to amino acid residues 414-434 in the V4-C4 region of gp120 of the HIV-1 Bru strain, potently reduced monocyte binding and chemotaxis response to macrophage inflammatory protein 1beta (MIP-1beta) and stromal cell-derived factor 1alpha (SDF-1alpha), chemokines that use the receptors CCR5 and CXCR4, respectively. Further study showed that F peptide by itself is an inducer of chemotaxis and calcium mobilization in human monocytes and neutrophils. In cross-desensitization experiments, among the numerous chemoattractants tested, only the bacterial chemotactic peptide fMLF, when used at high concentrations, partially attenuated calcium mobilization induced by F peptide in phagocytes, suggesting that this peptide domain might share a 7-transmembrane, G-protein-coupled receptor with fMLF. By using cells transfected with cDNAs encoding receptors that interact with fMLF, we found that F peptide uses an fMLF receptor variant, FPRL1, as a functional receptor. The activation of monocytes by F peptide resulted in downregulation of the cell surface expression of CCR5 and CXCR4 in a protein kinase C-dependent manner. These results demonstrate that activation of FPRL1 on human moncytes by a peptide domain derived from HIV-1 gp120 could lead to desensitization of cell response to other chemoattractants. This may explain, at least in part, the initial activation of innate immune responses in HIV-1-infected patients followed by immune suppression.

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