Extracellular HIV-1 Tat protein up-regulates the expression of surface CXC-chemokine receptor 4 in resting CD4+ T cells

Paola Secchiero, Davide Zella, Silvano Capitani, Robert C. Gallo, Giorgio Zauli

Research output: Contribution to journalArticlepeer-review

Abstract

Here we report that synthetic HIV-1 Tat protein, immobilized on a solid substrate, up-regulates the surface expression of the CXC-chemokine receptor 4 (CXCR4), but not of the CC-chemokine receptor 5 in purified populations of primary resting CD4+ T cells. The Tat-mediated increase of CXCR4 occurred in a well-defined range of concentrations (1-10 nM of immobilized Tat) and time period (4-8 h postincubation). Moreover, the increase of CXCR4 was accompanied by an increased entry of the HXB2 T cell line-tropic (X4-tropic), but not of the BaL macrophage-tropic strain of HIV-1. The ability of Tat to up-regulate CXCR4 expression was abrogated by the protein synthesis inhibitor cycloheximide, clearly indicating the requirement of de novo synthesis. As Tat protein is actively released by HIV-1 infected cells, our data indicate a potentially important role for extracellular Tat in rendering bystander CD4+ T cells more susceptible to infection with X4-tropic HIV-1 isolates.

Original languageEnglish
Pages (from-to)2427-2431
Number of pages5
JournalJournal of Immunology
Volume162
Issue number4
Publication statusPublished - Feb 15 1999

ASJC Scopus subject areas

  • Immunology

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