title: Ceramide-induced and age-associated increase in macrophage COX-2 expression is mediated through up-regulation of NF-kappa B activity.
abstract: We have shown that the age-associated increase in lipopolysaccharide (LPS)-stimulated macrophages (M phi) prostaglandin E(2) (PGE(2)) production is because of ceramide-induced up-regulation of cyclooxygenase (COX)-2 transcription that leads to increased COX-2 expression and enzyme activity. To determine the mechanism of the age-related and ceramide-dependent increase in COX-2 transcription, we investigated the role of various transcription factors involved in COX-2 gene expression. The results showed that LPS-initiated activations of both consensus and COX-2-specific NF-kappa B, but not AP-1 and CREB, were significantly higher in M phi from old mice than those from young mice. We further showed that the higher NF-kappa B activation in old M phi was because of greater I kappa B degradation in the cytoplasm and p65 translocation to the nucleus. An I kappa B phosphorylation inhibitor, Bay 11-7082, inhibited NF-kappa B activation, as well as PGE(2) production, COX activity, COX-2 protein, and mRNA expression in both young and old M phi. Similar results were obtained by blocking NF-kappa B binding activity using a NF-kappa B decoy. Furthermore, NF-kappa B inhibition resulted in significantly greater reduction in PGE(2) production and COX activity in old compared with young M phi. Addition of ceramide to the young M phi, in the presence or absence of LPS, increased NF-kappa B activation in parallel with PGE(2) production. Bay 11-7082 or NF-kappa B decoy prevented this ceramide-induced increase in NF-kappa B binding activity and PGE(2) production. These findings strongly suggest that the age-associated and ceramide-induced increase in COX-2 transcription is mediated through higher NF-kappa B activation, which is, in turn, because of a greater I kappa B degradation in old M phi.
authors.affiliation: Nutritional Immunology Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts 02111,USA.
authors.forename: Dayong
authors.initials: D
authors.lastname: Wu
authors.forename: Melissa
authors.initials: M
authors.lastname: Marko
authors.forename: Kate
authors.initials: K
authors.lastname: Claycombe
authors.forename: K Eric
authors.initials: KE
authors.lastname: Paulson
authors.forename: Simin Nikbin
authors.initials: SN
authors.lastname: Meydani
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002518:Ceramides / Q000494:pharmacology*; D051546:Cyclooxygenase 2; D017931:DNA Primers; D015232:Dinoprostone / Q000096:biosynthesis; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D002518:Ceramides; D017931:DNA Primers; D007527:Isoenzymes; D016328:NF-kappa B; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone