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

Abstract

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 phosphatidylcholinespecific 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 laserscanner 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-1␤) 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. (Blood. 2008;111:3355-3363)

HIV-1 gp120 Activates the STAT3/Interleukin-6 Axis in Primary Human Monocyte-Derived Dendritic Cells

“…However, nonselective cation channel activation was unique to gp120 (56). Furthermore, we have demonstrated that gp120 engagement of CCR5, but not CCL4, affects phosphatidylcholine-specific phospholipase C (PC-PLC) cellular distribution and enzymatic activity, as well as CCL2 secretion in primary macrophages (57). Likewise, in the same cell model, nuclear phosphoinositide-specific PLC-␤1 activation through CCR5 is triggered by both gp120 and CCL4 but via a different mechanism (58).…”

“…Previous studies aimed at characterizing signal transduction pathways triggered by gp120 upon coreceptor engagement revealed that while some of them are activated by both gp120 and CCL4, others are uniquely triggered by gp120 (54)(55)(56)(57)(58)(59)(60). In this respect, it was reported that gp120, as well as CCL4, opened calcium-activated potassium-, chloride-, and calcium-permeant nonselective cation channels in macrophages.…”

miR-27b*, an oxidative stress-responsive microRNA modulates nuclear factor-kB pathway in RAW 264.7 cells

“…Overexpression of miR-27b* mimics might negatively regulate its target proteins, which may be critical for NF-kB activation and the absence of these proteins in cells transfected with miR-27b* mimics might have led to either failure of NFkB activation or active suppression of NF-kB. To verify whether overexpression of miR-27b* can alter NF-kB-dependent gene expression, we measured mRNA expression for IL-1β, IL-6, TNF-α, and Ccl2 by TaqMan PCR analysis [40][41][42][43]. While there were no differences in the expression of IL-1β, IL-6, and TNF-α, Ccl2 mRNA expression was lower in the cells transfected with miR27b* mimics as compared with that of control mimics ( Figure 4c).…”

D609 Inhibits Progression of Preexisting Atheroma and Promotes Lesion Stability in Apolipoprotein E −/− Mice

“…8 Only scanty knowledge has been accumulated on expression, subcellular distribution, and activity of PC-PLC in several kinds of cells. 4,9,10 Because of the lack of structural and mechanistic information for mammalian PC-PLC, a specific PC-PLC inhibitor D609 and the activity assay for PC-PLC have been used as the most important tools for investigation of this important enzyme in mammalian cells. 8 Moreover, the present unavailability of specific monoclonal antibodies can be partly compensated by the use of rabbit polyclonal antibodies raised against bacterial (Bacillus cereus) PC-PLC, possessing proven selective cross-reactivity against mammalian PC-PLC.…”