title: PG201 downregulates the production of nitrite by upregulating heme oxygenase-1 expression through the control of phosphatidylinositol 3-kinase and NF-E2-related factor 2.
abstract: PG201 is an ethanol extract prepared from a specially designed botanical formulation and has previously been shown to contain strong anti-arthritic activities by controlling inflammation and cartilage destruction in two animal models [1,2]. In the present study, we evaluated the effects of PG201 on the expression of heme oxygenase-1 (HO-1). The treatment of Raw264.7 cells (a murine macrophage cell line) and bone marrow-derived macrophages (BMDMs) with PG201 increased the protein and RNA levels of HO-1. The results from a reporter plasmid assay indicated that PG201 induced HO-1 promoter activity through the stress response element present in the two enhancers of the HO-1 promoter. The treatment of cells with PG201 increased the total amount and the nuclear level of NF-E2-related factor 2 (Nrf2). Protein analysis using BMDMs from Nrf2 knockout mice showed that Nrf2 was necessary for the PG201-mediated induction of HO-1 expression. The PG201-mediated induction of these anti-oxidative stress factors was inhibited by a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), but not by inhibitors of p38, ERK and JNK mitogen-activated protein kinases. Furthermore, the results from an experiment involving a specific siRNA and chemical inhibitors for HO-1 showed that the PG201-mediated increase of the HO-1 protein contributed to the suppression of inducible nitric oxide synthase (iNOS) and nitrite production stimulated by lipopolysaccharide. Taken together, these results suggest that PG201 activates Nrf2 through the PI3K signal transduction pathway, increases the expression of HO-1, and subsequently decreases the production of iNOS and nitrite, eventually exerting anti-inflammatory activities.
authors.affiliation: School of Biological Sciences, Seoul National University, Seoul 151-742, South Korea.
authors.forename: Jinyong
authors.initials: J
authors.lastname: Choi
authors.forename: Junsub
authors.initials: J
authors.lastname: Lee
authors.forename: Junghun
authors.initials: J
authors.lastname: Lee
authors.forename: Seon-Hee
authors.initials: SH
authors.lastname: Kim
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Kim
authors.forename: Sunyoung
authors.initials: S
authors.lastname: Kim
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D051547:Heme Oxygenase-1 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D051267:NF-E2-Related Factor 2; D009573:Nitrites; D010936:Plant Extracts; C476094:herbal extract PG201; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051547:Heme Oxygenase-1; D019869:Phosphatidylinositol 3-Kinases
keywords: Heme oxygenase-1; Inducible nitric oxide synthase; Nitrite; Nrf2; PG201; Phosphatidylinositol 3-kinase