title: Lef1 regulates COX-2 transcription in chondrocytes.
abstract: Although the involvement of Wnt/beta-catenin signaling pathway in the regulation of COX-2 expression has been suggested, the underlying molecular mechanisms are still unclear. Here, we demonstrate that lymphoid enhancer-binding factor 1 (Lef1) in concert with beta-catenin is associated with the transcriptional regulation of the gene encoding COX-2 in mouse chondrocytes. Our results show that co-overexpression of Lef1 and beta-catenin synergistically upregulates COX-2 expression. Furthermore, decrease of Lef1 expression using Lef1 siRNA results in the downregulation of COX-2 expression. Using bioinformatic analysis, we identified a conserved Lef1-binding site that is mapped at the 3' region of the genomic COX-2 locus. In vivo and in vitro binding of Lef1 at the predicted binding site was proved using chromatin immunoprecipitation assays and electrophoretic mobility shift assays, respectively. Moreover, binding of Lef1 and beta-catenin to the Lef1-binding site transactivates COX-2 promoter activity. Our results indicate a pivotal role of Lef1 in the regulation of COX-2 transcription in arthritic chondrocytes.
authors.affiliation: Department of Life Sciences, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Puk-ku, Gwangju 500-712, Republic of Korea.
authors.forename: Kangsun
authors.initials: K
authors.lastname: Yun
authors.forename: Sin-Hyeog
authors.initials: SH
authors.lastname: Im
mesh_terms: D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D019295:Computational Biology; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D047468:Immunoprecipitation; D051821:Lymphoid Enhancer-Binding Factor 1 / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008813:Mice, Inbred ICR; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D051176:beta Catenin / Q000378:metabolism
chemical_list: C497574:Lef1 protein, mouse; D051821:Lymphoid Enhancer-Binding Factor 1; D051176:beta Catenin; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2