title: Glucocorticoid-induced leucine zipper (GILZ) mediates glucocorticoid action and inhibits inflammatory cytokine-induced COX-2 expression.
abstract: Cyclooxygenase-2 (COX-2) plays an important role in rheumatoid arthritis and therefore, has been a major target for anti-arthritis therapies. The expression of COX-2 is induced by inflammatory cytokines such as TNF-alpha and IL-1beta, and inhibited by glucocorticoids. However, the molecular mechanisms underlying the anti-inflammatory and immune suppressive actions of glucocorticoids are not well defined. Here we report that glucocorticoid-induced leucine zipper (GILZ) mimics glucocorticoid action and inhibits inflammatory cytokine-induced COX-2 expression in bone marrow mesenchymal stem cells, the cells that have been recently implicated in the pathogenesis and progression of rheumatoid arthritis. Using a retrovirus-mediated gene expression approach we demonstrate that overexpression of GILZ inhibits TNF-alpha and IL-1beta-induced COX-2 mRNA and protein expression, and knockdown of GILZ by shRNA reduces glucocorticoid inhibition of cytokine-induced COX-2 expression. Consistent to these results, overexpression of GILZ also inhibits NF-kappaB-mediated COX-2 promoter activity. Finally, we show that GILZ inhibits COX-2 expression by blocking NF-kappaB nuclear translocation. Our results suggest that GILZ is a key glucocorticoid effect mediator and that GILZ may have therapeutic value for novel anti-inflammation therapies.
authors.affiliation: Institute of Molecular Medicine & Genetics, Medical College of Georgia, Augusta, Georgia 30912, USA.
authors.forename: Nianlan
authors.initials: N
authors.lastname: Yang
authors.forename: Weixi
authors.initials: W
authors.lastname: Zhang
authors.forename: Xing-Ming
authors.initials: XM
authors.lastname: Shi
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D005938:Glucocorticoids / Q000494:pharmacology / Q000502:physiology*; D053583:Interleukin-1beta / Q000502:physiology*; D016350:Leucine Zippers; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: C498608:Dsip1 protein, mouse; D005938:Glucocorticoids; D053583:Interleukin-1beta; D016328:NF-kappa B; D012333:RNA, Messenger; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2