title: Inhibition of Nod2 signaling and target gene expression by curcumin.
abstract: Nod2 is an intracellular pattern recognition receptor that detects a conserved moiety of bacterial peptidoglycan and subsequently activates proinflammatory signaling pathways. Mutations in Nod2 have been implicated to be linked to inflammatory granulomatous disorders, such as Crohn's disease and Blau syndrome. Many phytochemicals possess anti-inflammatory properties. However, it is not known whether any of these phytochemicals might modulate Nod2-mediated immune responses and thus might be of therapeutic value for the intervention of these inflammatory diseases. In this report, we demonstrate that curcumin, a polyphenol found in the plant Curcuma longa, and parthenolide, a sesquiterpene lactone, suppress both ligand-induced and lauric acid-induced Nod2 signaling, leading to the suppression of nuclear factor-kappaB activation and target gene interleukin-8 expression. We provide molecular and biochemical evidence that the suppression is mediated through the inhibition of Nod2 oligomerization and subsequent inhibition of downstream signaling. These results demonstrate for the first time that curcumin and parthenolide can directly inhibit Nod2-mediated signaling pathways at the receptor level and suggest that Nod2-mediated inflammatory responses can be modulated by these phytochemicals. It remains to be determined whether these phytochemicals possess protective or therapeutic efficacy against Nod2-mediated inflammatory disorders.
authors.affiliation: Western Human Nutrition Research Center, United States Department of Agriculture, Agricultural Research Service, Davis, CA 95616, USA.
authors.forename: Shurong
authors.initials: S
authors.lastname: Huang
authors.forename: Ling
authors.initials: L
authors.lastname: Zhao
authors.forename: Kihoon
authors.initials: K
authors.lastname: Kim
authors.forename: Dong Seok
authors.initials: DS
authors.lastname: Lee
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Hwang
mesh_terms: D003474:Curcumin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D045325:HCT116 Cells; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D053473:Nod2 Signaling Adaptor Protein / Q000037:antagonists & inhibitors*; D010957:Plasmids; D015398:Signal Transduction / Q000187:drug effects*; D014162:Transfection
chemical_list: C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; D008156:Luciferases; D003474:Curcumin