Neutralising properties of peptides derived from CXCR4 extracellular loops towards CXCL12 binding and HIV-1 infection.
The chemokine receptor CXCR4 interacts with a single endogenous chemokine, CXCL12, and regulates a wide variety of physiological and pathological processes including inflammation and metastasis development. CXCR4 also binds the HIV-1 envelope glycoprotein, gp120, resulting in viral entry into host cells. Therefore, CXCR4 and its ligands represent valuable drug targets. In this study, we investigated the inhibitory properties of synthetic peptides derived from CXCR4 extracellular loops (ECL1-X4, ECL2-X4 and ECL3-X4) towards HIV-1 infection and CXCL12-mediated receptor activation. Among these peptides, ECL1-X4 displayed anti-HIV-1 activity against X4, R5/X4 and R5 viruses (IC50=24 to 76μM) in cell viability assay without impairing physiological CXCR4-CXCL12 signalling. In contrast, ECL2-X4 only inhibited X4 and R5/X4 strains, interfering with HIV-entry into cells. At the same time, ECL2-X4 strongly and specifically interacted with CXCL12, blocking its binding to CXCR4 and its second receptor, CXCR7 (IC50=20 and 100μM). Further analysis using mutated and truncated peptides showed that ECL2 of CXCR4 forms multiple contacts with the gp120 protein and the N-terminus of CXCL12. Chemokine neutralisation was mainly driven by four aspartates and the C-terminal residues of ECL2-X4. These results demonstrate that ECL2 represents an important structural determinant in CXCR4 activation. We identified the putative site for the binding of CXCL12 N-terminus and provided new structural elements to explain the recognition of gp120 and dimeric CXCR4 ligands.
Laboratoroire de Retrovirologie, Centre de Recherche Public de la Santé, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg. Electronic address: andy.chevigne@crp-sante.lu.
Andy
A
Chevigné
Laboratoroire de Retrovirologie, Centre de Recherche Public de la Santé, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg.
Virginie
V
Fievez
Laboratoroire de Retrovirologie, Centre de Recherche Public de la Santé, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg.
Martyna
M
Szpakowska
Laboratoroire de Retrovirologie, Centre de Recherche Public de la Santé, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg.
Aurélie
A
Fischer
Laboratoroire de Retrovirologie, Centre de Recherche Public de la Santé, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg.
Manuel
M
Counson
Laboratoroire de Retrovirologie, Centre de Recherche Public de la Santé, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg.
Jean-Marc
JM
Plesséria
Laboratoroire de Retrovirologie, Centre de Recherche Public de la Santé, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg; Service National des Maladies Infectieuses, Centre Hospitalier Luxembourg, 4, rue E. Barblé, L-1210 Luxembourg, Luxembourg.
Jean-Claude
JC
Schmit
Laboratoroire de Retrovirologie, Centre de Recherche Public de la Santé, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg.
Sabrina
S
Deroo
D000595:Amino Acid Sequence; D054377:Chemokine CXCL12 / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1; D006801:Humans; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D010455:Peptides / Q000276:immunology*; D019718:Receptors, CXCR4 / Q000276:immunology*
C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D010455:Peptides; D019718:Receptors, CXCR4
CXCL12; CXCR4; CXCR7; Extracellular loops; GPCR; HIV-1