Phosphatidylcholine-specific phospholipase C activation is required for CCR5-dependent, NF-kB-driven CCL2 secretion elicited in response to HIV-1 gp120 in human primary macrophages.
CCL2 (MCP-1) has been shown to enhance HIV-1 replication. The expression of this chemokine by macrophages is up-modulated as a consequence of viral infection or gp120 exposure. In this study, we show for the first time that the phosphatidylcholine-specific phospholipase C (PC-PLC) is required for the production of CCL2 triggered by gp120 in human monocyte-derived macrophages (MDMs). Using a combination of pharmacologic inhibition, confocal laser-scanner microscopy, and enzymatic activity assay, we demonstrate that R5 gp120 interaction with CCR5 activates PC-PLC, as assessed by a time-dependent modification of its subcellular distribution and a concentration-dependent increase of its enzymatic activity. Furthermore, PC-PLC is required for NF-kB-mediated CCL2 production triggered by R5 gp120. Notably, PC-PLC activation through CCR5 is specifically induced by gp120, since triggering CCR5 through its natural ligand CCL4 (MIP-1beta) does not affect PC-PLC cellular distribution and enzymatic activity, as well as CCL2 secretion, thus suggesting that different signaling pathways can be activated through CCR5 interaction with HIV-1 or chemokine ligands. The identification of PC-PLC as a critical mediator of well-defined gp120-mediated effects in MDMs unravels a novel mechanism involved in bystander activation and may contribute to define potential therapeutic targets to block Env-triggered pathologic responses.
Fantuzzi
Laura
L
Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy.
Spadaro
Francesca
F
Purificato
Cristina
C
Cecchetti
Serena
S
Podo
Franca
F
Belardelli
Filippo
F
Gessani
Sandra
S
Ramoni
Carlo
C
D024201:Bystander Effect / Q000235:genetics; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism*; D054407:Chemokine CCL4; D004789:Enzyme Activation / Q000235:genetics; D015699:HIV Envelope Protein gp120 / Q000235:genetics / Q000378:metabolism*; D015658:HIV Infections / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology / Q000821:virology; D018613:Microscopy, Confocal; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D019713:Receptors, CCR5 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D013997:Time Factors; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication / Q000235:genetics
C111835:CCL2 protein, human; C066507:CCL4 protein, human; D018932:Chemokine CCL2; D054407:Chemokine CCL4; D015699:HIV Envelope Protein gp120; D016328:NF-kappa B; D019713:Receptors, CCR5; C514793:gp120 protein, Human immunodeficiency virus 1; D010738:Type C Phospholipases; C105598:phosphatidylcholine-specific phospholipase C