title: Nitric oxide inhibits interleukin-12 p40 through p38 MAPK-mediated regulation of calmodulin and c-rel.
abstract: 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.
authors.affiliation: Laboratory of Molecular and Cellular Biology, Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Nacharam, Hyderabad 500076, Andhra Pradesh, India.
authors.forename: Chandra Sekhar
authors.initials: CS
authors.lastname: Boddupalli
authors.forename: Sudip
authors.initials: S
authors.lastname: Ghosh
authors.forename: Sheikh Showkat
authors.initials: SS
authors.lastname: Rahim
authors.forename: Shiny
authors.initials: S
authors.lastname: Nair
authors.forename: Nasreen Z
authors.initials: NZ
authors.lastname: Ehtesham
authors.forename: Seyed E
authors.initials: SE
authors.lastname: Hasnain
authors.forename: Sangita
authors.initials: S
authors.lastname: Mukhopadhyay
mesh_terms: 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*
chemical_list: 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