P2X1 Receptor Antagonists Inhibit HIV-1 Fusion by Blocking Virus-Coreceptor Interactions

• Type of Material: Article
• Authors: Charline Giroud, Emory University; Mariana Marin, Emory University; Jason Hammonds, Emory University; Paul Spearman, Emory University; Gregory Melikian, Emory University
• Language: English
• Date: 2015-09-01
• Publisher: American Society for Microbiology
• Publication Version: Final Published Version
• Copyright Statement: © 2015, American Society for Microbiology.
• Final Published Version (URL): http://dx.doi.org/10.1128/JVI.01178-15
• Title of Journal or Parent Work: Journal of Virology
• ISSN: 0022-538X
• Volume: 89
• Issue: 18
• Start Page: 9368
• End Page: 9382
• Grant/Funding Information: This work was supported by NIH R01 grants GM108480 and GM054787 to G.B.M. and grant R01 AI058828 to P.S.
• Keywords: INFECTION; CCR5 ANTAGONISTS; HUMAN-IMMUNODEFICIENCY-VIRUS; ENTRY INHIBITORS; Vaccines and Antiviral Agents; SMALL-MOLECULE; ATP RELEASE; Life Sciences & Biomedicine; AMINO-ACID RESIDUE; Virology; MEMBRANE-FUSION; PURINERGIC RECEPTORS; Science & Technology; T-CELL-ACTIVATION
• Research Categories: Biology, Virology; Health Sciences, Pharmacology; Health Sciences, Medicine and Surgery

Abstract

HIV-1 Env glycoprotein-mediated fusion is initiated upon sequential binding of Env to CD4 and the coreceptor CXCR4 or CCR5. Whereas these interactions are thought to be necessary and sufficient to promote HIV-1 fusion, other host factors can modulate this process. Previous studies reported potent inhibition of HIV-1 fusion by selective P2X1 receptor antagonists, including NF279, and suggested that these receptors play a role in HIV-1 entry. Here we investigated the mechanism of antiviral activity of NF279 and found that this compound does not inhibit HIV-1 fusion by preventing the activation of P2X1 channels but effectively blocks the binding of the virus to CXCR4 or CCR5. The notion of an off-target effect of NF279 on HIV-1 fusion is supported by the lack of detectable expression of P2X1 receptors in cells used in fusion experiments and by the fact that the addition of ATP or the enzymatic depletion of ATP in culture medium does not modulate viral fusion. Importantly, NF279 fails to inhibit HIV-1 fusion with cell lines and primary macrophages when added at an intermediate stage downstream of Env-CD4-coreceptor engagement. Conversely, in the presence of NF279, HIV-1 fusion is arrested downstream of CD4 binding but prior to coreceptor engagement. NF279 also antagonizes the signaling function of CCR5, CXCR4, and another chemokine receptor, as evidenced by the suppression of calcium responses elicited by specific ligands and by recombinant gp120. Collectively, our results demonstrate that NF279 is a dual HIV-1 coreceptor inhibitor that interferes with the functional engagement of CCR5 and CXCR4 by Env.