title: BMP-2 induction of Dlx3 expression is mediated by p38/Smad5 signaling pathway in osteoblastic MC3T3-E1 cells.
abstract: Dlx3 is essential for osteoblast differentiation and bone formation, and its expression is regulated by bone morphogenetic protein-2 (BMP-2). However, the intimate mechanism of BMP-2 regulation of Dlx3 transcription in osteoblasts is still unknown. Considering the important roles of Smad5 and p38 in osteoblast differentiation, we hypothesized that Smad5 and p38 mediated BMP-2-induced Dlx3 transcription in osteoblasts. We found activation of Smad5 and p38 increased the expression of Dlx3, whereas knocking down Smad5 or inactivation of p38 inhibited BMP-2-induced Dlx3 expression. Both Smad5 and p38 were able to activate Dlx3 promoter activity and p38/Smad5 response elements were located from -698 to -368 in Dlx3 promoter. Two Smad5 binding sites (SBEI and SBEII, TGTCT box) were identified in this region by EMSA and ChIP assay. Deletions and mutagenesis study of the Dlx3 promoter region indicated that the TGTCT boxes are crucial for p38/Smad5-induced Dlx3 promoter activity. At last, we found a cross-talk between p38 and Smad5, and that activation of p38 is necessary for BMP-2-induced Smad5 phosphorylation and nuclear translocation. Overall, we provide a novel insight that BMP-2-induced Dlx3 expression is regulated by p38/Smad5 signaling pathway in osteoblasts.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Guobin
authors.initials: G
authors.lastname: Yang
authors.forename: Guohua
authors.initials: G
authors.lastname: Yuan
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Li
authors.forename: Pingxian
authors.initials: P
authors.lastname: Liu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Mingwen
authors.initials: M
authors.lastname: Fan
mesh_terms: D055396:Bone Morphogenetic Protein 2 / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D051902:Smad5 Protein / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism
chemical_list: C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; C088334:Distal-less homeobox proteins; D018398:Homeodomain Proteins; D051902:Smad5 Protein; C497798:Smad5 protein, mouse; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D048051:p38 Mitogen-Activated Protein Kinases