Effects of melanocortin peptides on lipopolysaccharide/interferon-gamma-induced NF-kappaB DNA binding and nitric oxide production in macrophage-like RAW 264.7 cells: evidence for dual mechanisms of action.
The pro-opiomelanocortin-derived peptide alpha-melanocyte-stimulating hormone (alpha-MSH) mediates broad anti-inflammatory and immunomodulatory effects, which include inhibition of the production and release of proinflammatory cytokines and nitric oxide (NO) from macrophages. We investigated the effects of alpha-MSH, alpha-MSH(1-10), and alpha-MSH(11-13) on NO production and nuclear factor-kappaB (NF-kappaB) translocation in RAW 264.7 macrophages. After stimulation of the cells with bacterial lipopolysaccharide/interferon-gamma (LPS/IFN-gamma), all three peptides inhibited NO production with an order of potency alpha-MSH > or = alpha-MSH(11-13) > alpha-MSH(1-10). All three MSH peptides inhibited NF-kappaB nuclear translocation with the maximal effect of alpha-MSH and alpha-MSH(11-13) being seen in the range 1 nM-1 microM, and that of alpha-MSH(1-10) at 1 microM. By use of (125)I-(Nle(4),D-Phe(7))alpha-MSH(NDP-MSH) radioligand binding, MC(1) receptor-binding sites were demonstrated on RAW 264.7 cells. alpha-MSH and alpha-MSH(1-10) competed with the (125)I-NDP-MSH binding at these MC(1) receptor-binding sites, but alpha-MSH(11-13) even in concentrations up to 1 mM did not. Moreover, alpha-MSH and alpha-MSH(1-10) caused powerful stimulation of cyclic 3',5'-adenosine monophosphate (cAMP) in the RAW 264.7 cell, whereas alpha-MSH(11-13) was ineffective. Forskolin stimulated cAMP and inhibited NO production to the same extent as alpha-MSH and alpha-MSH(1-10), but did not modify the translocation of NF-kappaB. Whereas the protein kinase A inhibitor H89 did not modify the effect of alpha-MSH on NF-kappaB translocation, H89 caused a partial inhibition of the inhibitory effect of alpha-MSH, alpha-MSH(1-10), alpha-MSH(11-13), and forskolin on NO production. In addition alpha-MSH, alpha-MSH(1-10), alpha-MSH(11-13), and forskolin also inhibited the activity of an NF-kappaB-dependent luciferase reporter and these effects were partially counteracted by H89. We suggest that melanocortin peptides act via dual mechanisms of action: one cAMP-independent and causing inhibition of NF-kappaB translocation and the other dependent on MC(1) receptor/cAMP activation.
Department of Pharmaceutical Pharmacology, Uppsala University, Box 591, BMC, SE-75124, Uppsala, Sweden.
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Mandrika
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Muceniece
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Wikberg
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017930:Genes, Reporter; D007371:Interferon-gamma / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D018043:Receptors, Corticotropin / Q000378:metabolism; D044101:Receptors, Melanocortin; D013449:Sulfonamides; D000521:alpha-MSH / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D007546:Isoquinolines; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009573:Nitrites; D010455:Peptides; D018043:Receptors, Corticotropin; D044101:Receptors, Melanocortin; D013449:Sulfonamides; D005576:Colforsin; D009569:Nitric Oxide; D000521:alpha-MSH; D007371:Interferon-gamma; D004247:DNA; D000242:Cyclic AMP; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide