Tat–Human Immunodeficiency Virus-1 Induces Human Monocyte Chemotaxis by Activation of Vascular Endothelial Growth Factor Receptor-1 (original) (raw)
Human immunodeficiency virus-1 (HIV-1) Tat protein can be firming the common use of this receptor. Binding studies performed at equilibrium by using radiolabeled Tat showed released by infected cells and activates mesenchymal cells. Among these, monocytes respond to Tat by migrating into that monocytes expressed a unique class of binding site, with a kd of approximately 0.2 nmol/L. The binding of radio-tissues and releasing inflammatory mediators. In the present study, we have examined the molecular mechanism of labeled Tat to monocyte surface and the cross-linking to a protein of 150 kD was inhibited specifically by an excess of monocyte activation by Tat, showing that this viral protein signals inside the cells through the tyrosine kinase receptor cold Tat or VEGF-A. Western blot analysis with an antibody anti-VEGFR-1/Flt-1 performed on monocyte phosphopro-for vascular endothelial growth factor encoded by fms-like tyrosine kinase gene (VEGFR-1/Flt-1). Subnanomolar con-teins immunoprecipitated by an monoclonal antibody antiphosphotyrosine showed that Tat induced a rapid phosphor-centrations of Tat induced monocyte chemotaxis, which was inhibited by cell preincubation with vascular-endothelial ylation in tyrosine residue of the 150-kD VEGFR-1/Flt-1. Taken together, these results suggest that biologic activities growth factor-A (VEGF-A). This desensitisation was specific for VEGF-A, because it not was observed with FMLP. In addi-of HIV-1 Tat in human monocytes may, at least in part, be elicited by activation of VEGFR-1/Flt-1. tion, the soluble form of VEGFR-1 specifically inhibited polarization and migration induced by Tat and VEGF-A, thus con-᭧ 1997 by The American Society of Hematology. growth factor), 24 we have recently shown that the tyrosine
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