title: TNFα Increases RANKL Expression via PGE₂-Induced Activation of NFATc1.
abstract: Tumor necrosis factor α (TNFα) is known to upregulate the expression of receptor activator of NF-κB ligand (RANKL). We investigated the role of the calcineurin/nuclear factor of activated T-cells (NFAT) signaling pathway in TNFα-inducedRANKLexpression in C2C12 and primary cultured mouse calvarial cells. TNFα-inducedRANKLexpression was blocked by the calcineurin/NFAT pathway inhibitors. TNFα increased NFAT transcriptional activity and subsequentRANKLpromoter binding. Mutations in the NFAT-binding element (MT(N)) suppressed TNFα-inducedRANKLpromoter activity. TNFα increased prostaglandin E2 (PGE₂) production, which in turn enhanced NFAT transcriptional activity and binding to theRANKLpromoter. MT(N) suppressed PGE₂-inducedRANKLpromoter activity. TNFα and PGE₂ increased the expression ofRANKL, NFAT cytoplasmic-1 (NFATc1), cAMP response element-binding protein (CREB), and cyclooxygenase 2 (COX2); which increment was suppressed by indomethacin, a COX inhibitor. Mutations in the CRE-like element blocked PGE₂-inducedRANKLpromoter activity. PGE₂ induced the binding of CREB to theRANKLpromoter, whereas TNFα increased the binding of both CREB and NFATc1 to this promoter through a process blocked by indomethacin. The PGE₂ receptor antagonists AH6809 and AH23848 blocked TNFα-induced expression ofRANKL, NFATc1, and CREB; transcriptional activity of NFAT; and binding of NFATc1 or CREB to theRANKLpromoter. These results suggest that TNFα-inducedRANKLexpression depends on PGE₂ production and subsequent transcriptional activation/enhanced binding of NFATc1 and CREB to theRANKLpromoter.
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 08826, Korea. in2010@snu.ac.kr.
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Park
authors.affiliation: Department of Pharmacology, College of Dentistry and Research Institute of Oral Science, Gangneung-Wonju National University, Gangwon-do 25457, Korea. daedanhae@gmail.com.
authors.forename: Kyunghwa
authors.initials: K
authors.lastname: Baek
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 08826, Korea. baekjh@snu.ac.kr.
authors.forename: Jeong-Hwa
authors.initials: JH
authors.lastname: Baek
authors.affiliation: Graduate School, DGIST, Daegu 42988, Korea. hrkim@dgist.ac.kr.
authors.forename: Hyung-Ryong
authors.initials: HR
authors.lastname: Kim
mesh_terms: D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D019703:Calcineurin / Q000378:metabolism; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D051379:Mice; D050778:NFATC Transcription Factors / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D053245:RANK Ligand / Q000235:genetics*; D020218:Response Elements; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology; D044004:Xanthones / Q000494:pharmacology
chemical_list: D001713:Biphenyl Compounds; D017362:Cyclic AMP Response Element-Binding Protein; D050778:NFATC Transcription Factors; D053245:RANK Ligand; D014409:Tumor Necrosis Factor-alpha; D044004:Xanthones; C053876:6-isopropoxy-9-oxoxanthene-2-carboxylic acid; C046926:AH 23848; D051546:Cyclooxygenase 2; D019703:Calcineurin; D015232:Dinoprostone
keywords: CREB; NFATc1; PGE2; RANKL; TNFα