title: Bmal1 induces osteoblast differentiation via regulation of BMP2 expression in MC3T3-E1 cells.
abstract: OBJECTIVE
  Mammalian circadian rhythms regulate many metabolic processes. Recent studies suggest that brain and muscle Arnt-like 1 (BMAL1), an important component of mammalian circadian rhythm, is associated with insulin signaling. Several studies have shown that insulin is associated with bone metabolism; however, the relationship between BMAL1 and osteoblasts remains unclear.
  
  
  METHODS
  Expression of osteogenic markers and Bmal1 in MC3T3-E1 cells was measured by RT-PCR and Western blotting. Alizarin red S staining was performed to assess matrix mineralization in MC3T3-E1 cells.
  
  
  RESULTS
  mRNA levels of osteogenic genes and Bmal1 were up-regulated in MC3T3-E1 cells upon insulin treatment. In addition, Bmal1 overexpression increased the expression of osteogenic genes including inhibitor of DNA binding (Id1), Runt-related transcription factor 2 (Runx2), and osteocalcin (OC). Interestingly, expression of Bone morphogenetic protein-2 (BMP2), an important upstream factor of Id1, Runx2, and OC, was markedly increased by Bmal1. Finally, we confirmed that insulin-induced BMP2 expression was attenuated in Bmal1 knockout (KO) cells. PCR analysis and alizarin red S staining showed that insulin-mediated increases gene expression and calcium deposition were reduced in Bmal1 KO cells compared to wild-type cells.
  
  
  CONCLUSIONS
  Taken together, these results demonstrate that Bmal1 promotes osteoblast differentiation by regulating BMP2 expression in MC3T3-E1 cells.
authors: Department of Biotechnology, College of Engineering, Daegu University, Gyeongbuk 38453, Republic of Korea; Research Institute of Anti-Aging, Daegu University, Gyeongbuk 38453, Republic of Korea. Electronic address: jminhy@gmail.com.
authors: Hyeon-Young
authors: HY
authors: Min
authors: Department of Biotechnology, College of Engineering, Daegu University, Gyeongbuk 38453, Republic of Korea; Research Institute of Anti-Aging, Daegu University, Gyeongbuk 38453, Republic of Korea. Electronic address: kkm97655@naver.com.
authors: Kyeong-Min
authors: KM
authors: Kim
authors: Laboratory Animal Center, Daegu-Gyeongbuk Medical Innovation Foundation (DGMIF), 80 Cheombok-ro, Dong-gu, Daegu 41061, Republic of Korea. Electronic address: gabbine@dgmif.re.kr.
authors: Gabbine
authors: G
authors: Wee
authors: Research Institute of Anti-Aging, Daegu University, Gyeongbuk 38453, Republic of Korea. Electronic address: ejkim4164@gamil.com.
authors: Eun-Jung
authors: EJ
authors: Kim
authors: Department of Biotechnology, College of Engineering, Daegu University, Gyeongbuk 38453, Republic of Korea; Research Institute of Anti-Aging, Daegu University, Gyeongbuk 38453, Republic of Korea. Electronic address: jangwg@daegu.ac.kr.
authors: Won-Gu
authors: WG
authors: Jang
mesh_terms: D016475:3T3 Cells; D056930:ARNTL Transcription Factors / Q000502:physiology*; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology*
chemical_list: D056930:ARNTL Transcription Factors; C538961:Bmal1 protein, mouse; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2
keywords: BMP2; Bmal1; Insulin; Osteoblast differentiation