title: Bone morphogenetic protein-2 functions as a negative regulator in the differentiation of myoblasts, but not as an inducer for the formations of cartilage and bone in mouse embryonic tongue.
abstract: BACKGROUND
  In vitro studies using the myogenic cell line C2C12 demonstrate that bone morphogenetic protein-2 (BMP-2) converts the developmental pathway of C2C12 from a myogenic cell lineage to an osteoblastic cell lineage. Further, in vivo studies using null mutation mice demonstrate that BMPs inhibit the specification of the developmental fate of myogenic progenitor cells. However, the roles of BMPs in the phases of differentiation and maturation in skeletal muscles have yet to be determined. The present study attempts to define the function of BMP-2 in the final stage of differentiation of mouse tongue myoblast.
  
  
  RESULTS
  Recombinant BMP-2 inhibited the expressions of markers for the differentiation of skeletal muscle cells, such as myogenin, muscle creatine kinase (MCK), and fast myosin heavy chain (fMyHC), whereas BMP-2 siRNA stimulated such markers. Neither the recombinant BMP-2 nor BMP-2 siRNA altered the expressions of markers for the formation of cartilage and bone, such as osteocalcin, alkaline phosphatase (ALP), collagen II, and collagen X. Further, no formation of cartilage and bone was observed in the recombinant BMP-2-treated tongues based on Alizarin red and Alcian blue stainings. Neither recombinant BMP-2 nor BMP-2 siRNA affected the expression of inhibitor of DNA binding/differentiation 1 (Id1). The ratios of chondrogenic and osteogenic markers relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH, a house keeping gene) were approximately 1000-fold lower than those of myogenic markers in the cultured tongue.
  
  
  CONCLUSIONS
  BMP-2 functions as a negative regulator for the final differentiation of tongue myoblasts, but not as an inducer for the formation of cartilage and bone in cultured tongue, probably because the genes related to myogenesis are in an activation mode, while the genes related to chondrogenesis and osteogenesis are in a silencing mode.
authors: Department of Orthodontics, Tsurumi University School of Dental Medicine, Yokohama, Japan.
authors: Kayoko
authors: K
authors: Aoyama
authors: Akira
authors: A
authors: Yamane
authors: Takeo
authors: T
authors: Suga
authors: Erika
authors: E
authors: Suzuki
authors: Tadayoshi
authors: T
authors: Fukui
authors: Yoshiki
authors: Y
authors: Nakamura
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism*; D001842:Bone and Bones / Q000166:cytology / Q000378:metabolism; D002356:Cartilage / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D020219:Chondrogenesis / Q000235:genetics; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D024510:Muscle Development; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010012:Osteogenesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000378:metabolism; D014059:Tongue / Q000166:cytology / Q000196:embryology*
chemical_list: D055396:Bone Morphogenetic Protein 2; D034741:RNA, Small Interfering