title: n-Propyl gallate suppresses lipopolysaccharide-induced inducible nitric oxide synthase activation through protein kinase Cδ-mediated up-regulation of heme oxygenase-1 in RAW264.7 macrophages.
abstract: n-Propyl gallate is a synthetic phenolic antioxidant with potential anti-inflammatory effects. However, the underlying mechanism remains largely unknown. In the present study, we showed that n-propyl gallate increases the expression and activity of the heme oxygenase-1 (HO-1), a stress-inducible protein with potent anti-inflammatory activity, in RAW264.7 macrophages. The inhibition of the HO-1 activity by treatment with zinc (II) protoporphyrin IX (ZnPP) or by knockdown of the HO-1 expression with small interference RNA significantly reversed the inhibitory effect of n-Propyl gallate on activations of nuclear factor-κB (NF-κB) and inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide (LPS). An additional mechanism study using inhibitors of signaling kinases revealed the involvement of protein kinase Cδ (PKCδ) in the expression of HO-1 induced by n-Propyl gallate. Consistent with these results, n-Propyl gallate increased the intracellular levels of phosphorylated PKCδ in concentration- and time-dependent manners. The inhibitory effects of n-Propyl gallate on LPS-induced iNOS expression and nitric oxide production were also significantly attenuated by pretreatment with the PKCδ inhibitor, rottlerin, or by transfection with PKCδ (K376R), a kinase-inactive form of PKCδ. Taken together, these findings provide the first evidence that n-Propyl gallate exerts its anti-inflammatory effect through PKCδ-mediated up-regulation of HO-1 in macrophages.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 24341, Republic of Korea.
authors.forename: Wookwang
authors.initials: W
authors.lastname: Jeon
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 24341, Republic of Korea.
authors.forename: Seong Ji
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 24341, Republic of Korea. Electronic address: bckim@kangwon.ac.kr.
authors.forename: Byung-Chul
authors.initials: BC
authors.lastname: Kim
mesh_terms: D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D011435:Propyl Gallate / Q000494:pharmacology*; D051745:Protein Kinase C-delta / Q000378:metabolism*; D000067996:RAW 264.7 Cells; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D008070:Lipopolysaccharides; D016328:NF-kappa B; D009569:Nitric Oxide; D011435:Propyl Gallate; D052247:Nitric Oxide Synthase Type II; D051547:Heme Oxygenase-1; D051745:Protein Kinase C-delta
keywords: Anti-inflammatory; HO-1; Macrophages; PKCδ; iNOS; n-Propyl gallate