Nitric oxide inhibits interleukin-12 p40 through p38 MAPK-mediated regulation of calmodulin and c-rel.
In activated macrophages, the rel/NF-kappaB transcription factors are known to play important roles in interleukin-12 (IL-12) p40 regulation by nitric oxide (NO). However, the relative contributions of these factors are not well understood. Here, we describe a dominant role for c-rel involving p38 mitogen-activated protein kinase (p38 MAPK) and calmodulin (CaM) protein in NO-mediated IL-12 p40 inhibition in activated macrophages. Inhibition of NO production by aminoguanidine increased, whereas sodium nitroprusside (SNP; an exogenous NO generator) reduced, nuclear c-rel levels in LPS + IFN-gamma-activated RAW 264.7 macrophages. Overexpression of c-rel but not p65 NF-kappaB increased IL-12 p40 during NO treatment. The p38 MAPK phosphorylation is increased by NO, and inhibition of p38 MAPK in SNP-treated macrophages by SB203580 or transient expression of a dominant-negative mutant of p38 MAPK upregulated both nuclear c-rel and IL-12 p40 levels, indicating that NO targeted the p38 MAPK pathway to inhibit c-rel and IL-12 p40. Cytoplasmic CaM level was increased by NO, and SB203580 decreased the CaM level in NO-exposed macrophages. Inhibition of CaM activity by trifluoperazine rescued the inhibitory effect of NO on c-rel and IL-12 p40. Our findings indicate that c-rel plays an important role in NO-mediated inhibition of IL-12 p40 and is regulated by p38 MAPK through CaM protein.
Boddupalli
Chandra Sekhar
CS
Laboratory of Molecular and Cellular Biology, Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Nacharam, Hyderabad 500076, Andhra Pradesh, India.
Ghosh
Sudip
S
Rahim
Sheikh Showkat
SS
Nair
Shiny
S
Ehtesham
Nasreen Z
NZ
Hasnain
Seyed E
SE
Mukhopadhyay
Sangita
S
D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002478:Cells, Cultured; D006146:Guanidines / Q000494:pharmacology; D053762:Interleukin-12 Subunit p40 / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000494:pharmacology*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D020569:Proto-Oncogene Proteins c-rel / Q000378:metabolism* / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology*
D002147:Calmodulin; D006146:Guanidines; D053762:Interleukin-12 Subunit p40; D020569:Proto-Oncogene Proteins c-rel; D009599:Nitroprusside; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D048051:p38 Mitogen-Activated Protein Kinases; C004479:pimagedine