title: Smurf1 plays a role in EGF inhibition of BMP2-induced osteogenic differentiation.
abstract: It has been demonstrated that epidermal growth factor (EGF) plays a role in supporting the proliferation of bone marrow stromal cells in bone but inhibits their osteogenic differentiation. However, the mechanism underlying EGF inhibition of osteoblast differentiation remains unclear. Smurf1 is an E3 ubiquitin ligase that targets Smad1/5 and Runx2, which are critical transcription factors for bone morphogenetic protein 2 (BMP2)-induced osteoblast differentiation. In this study, we investigated the effect of EGF on the expression of Smurf1, and the role of Smurf1 in EGF inhibition of osteogenic differentiation using C2C12 cells, a murine myoblast cell line. EGF increased Smurf1 expression, which was blocked by inhibiting the activity of either JNK or ERK. Chromatin immunoprecipitation and Smurf1 promoter assays demonstrated that c-Jun and Runx2 play roles in the EGF induction of Smurf1 transcription. EGF suppressed BMP2-induced expression of osteogenic marker genes, which were rescued by Smurf1 knockdown. EGF downregulated the protein levels of Runx2 and Smad1 in a proteasome-dependent manner. EGF decreased the transcriptional activity of Runx2 and Smurf1, which was partially rescued by Smurf1 silencing. Taken together, these results suggest that EGF increases Smurf1 expression via the activation of JNK and ERK and the subsequent binding of c-Jun and Runx2 to the Smurf1 promoter and that Smurf1 mediates the inhibitory effect of EGF on BMP2-induced osteoblast differentiation.
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea.
authors.forename: Hye-Lim
authors.initials: HL
authors.lastname: Lee
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea.
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Park
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea.
authors.forename: Arang
authors.initials: A
authors.lastname: Kwon
authors.affiliation: Department of Pharmacology, College of Dentistry and Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung 210-702, Gangwondo, Republic of Korea.
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 110-749, Republic of Korea.
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Woo
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea.
authors.forename: Hyun-Mo
authors.initials: HM
authors.lastname: Ryoo
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea.
authors.forename: Gwan-Shik
authors.initials: GS
authors.lastname: Kim
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749, Republic of Korea. Electronic address: baekjh@snu.ac.kr.
authors.forename: Jeong-Hwa
authors.initials: JH
authors.lastname: Baek
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D047093:Eosinophil Major Basic Protein / Q000235:genetics / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010012:Osteogenesis; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051898:Smad1 Protein / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; C479219:Prg3 protein, mouse; D047428:Protein Kinase Inhibitors; D051898:Smad1 Protein; D004815:Epidermal Growth Factor; C492381:Smurf1 protein, mouse; D044767:Ubiquitin-Protein Ligases; D048049:Extracellular Signal-Regulated MAP Kinases; D047093:Eosinophil Major Basic Protein
keywords: BMP2; Differentiation; EGF; Osteoblast; Smurf1