title: SMILE inhibits BMP-2-induced expression of osteocalcin by suppressing the activity of the RUNX2 transcription factor in MC3T3E1 cells.
abstract: Small heterodimer partner interacting leucine zipper protein (SMILE) is an orphan nuclear receptor and a member of the bZIP family of proteins. Several recent studies have suggested that SMILE is a novel co-repressor that is involved in nuclear receptor signaling; however, the role of SMILE in osteoblast differentiation has not yet been elucidated. This study demonstrates that SMILE inhibits osteoblast differentiation by regulating the activity of Runt-related transcription factor-2 (RUNX2). Tunicamycin, an inducer of endoplasmic reticulum stress, stimulated SMILE expression. Bone morphogenetic protein-2-induced expression of alkaline phosphatase and osteocalcin, both of which are osteogenic genes, was suppressed by SMILE. The molecular mechanism by which SMILE affects osteocalcin expression was also determined. An immunoprecipitation assay revealed a physical interaction between SMILE and RUNX2 that significantly impaired the RUNX2-dependent activation of the osteocalcin gene. A ChIP assay revealed that SMILE repressed the ability of RUNX2 to bind to the osteocalcin gene promoter. Taken together, these findings demonstrate that SMILE negatively regulates osteocalcin via a direct interaction with RUNX2.
authors.affiliation: Research Center of Integrative Cellulomics, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea; Functional Genomics, School of Engineering, University of Science and Technology (UST), Daejeon 305-806, Republic of Korea.
authors.forename: Hoon
authors.initials: H
authors.lastname: Jang
authors.affiliation: Research Center of Integrative Cellulomics, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea.
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Kim
authors.affiliation: Research Center of Integrative Cellulomics, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea.
authors.forename: Jae-Kyung
authors.initials: JK
authors.lastname: Park
authors.affiliation: Research Center of Integrative Cellulomics, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea.
authors.forename: Dong-Ern
authors.initials: DE
authors.lastname: Kim
authors.affiliation: Research Center of Integrative Cellulomics, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea.
authors.forename: Hyoung-Joo
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Research Center of Integrative Cellulomics, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea.
authors.forename: Wu-Sheng
authors.initials: WS
authors.lastname: Sun
authors.affiliation: Animal Biotechnology Division, National Institute of Animal Science, Rural Development Administration, Suwon, Republic of Korea.
authors.forename: Seongsoo
authors.initials: S
authors.lastname: Hwang
authors.affiliation: Animal Biotechnology Division, National Institute of Animal Science, Rural Development Administration, Suwon, Republic of Korea.
authors.forename: Keon-Bong
authors.initials: KB
authors.lastname: Oh
authors.affiliation: Department of Pharmacology and Dental Therapeutics and Research Center for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Jeong-Tae
authors.initials: JT
authors.lastname: Koh
authors.affiliation: Department of Biotechnology, School of Engineering, Daegu University, Gyeongbuk 712-714, Republic of Korea. Electronic address: jangwg@daegu.ac.kr.
authors.forename: Won-Gu
authors.initials: WG
authors.lastname: Jang
authors.affiliation: Research Center of Integrative Cellulomics, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea; Functional Genomics, School of Engineering, University of Science and Technology (UST), Daejeon 305-806, Republic of Korea. Electronic address: jwlee@kribb.re.kr.
authors.forename: Jeong-Woong
authors.initials: JW
authors.lastname: Lee
mesh_terms: D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism*; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D047369:Chromatin Immunoprecipitation; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D015675:Osteocalcin / Q000096:biosynthesis*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C525718:BMP2 protein, human; D050976:Basic-Leucine Zipper Transcription Factors; D055396:Bone Morphogenetic Protein 2; D050659:Core Binding Factor Alpha 1 Subunit; C493716:Runx2 protein, mouse; C570109:SMILE protein, mouse; D015675:Osteocalcin
keywords: BMP2; Osteoblast; Osteocalcin; Runx2; SMILE