title: Transcriptional mechanisms in osteoblast differentiation and bone formation.
abstract: Osteoblasts, the cells responsible for bone formation, differentiate from mesenchymal cells. Here, we discuss transcription factors that are involved in regulating the multistep molecular pathway of osteoblast differentiation. Runx2 and Osx, a newly identified zinc-finger-containing protein, are transcription factors that are expressed selectively and at high levels in osteoblasts. Null mutations of either leads to a complete absence of bone in mice. Runx2 plus its companion subunit Cbf beta are needed for an early step in this pathway, whereas Osx is required for a subsequent step, namely the differentiation of preosteoblasts into fully functioning osteoblasts. The finding that Osx-null cells acquire a chondrocyte phenotype implies that Osx is a negative regulator of Sox9 and of the chondrocyte phenotype. This leads to the hypothesis that Osx might have a role in the segregation of osteoblasts from osteochondroprogenitors. We also discuss recent progress in studies of other transcription factors that affect skeletal patterning and development.
authors.affiliation: Department of Molecular Genetics, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA. knakashi@mail.mdanderson.org
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Nakashima
authors.forename: Benoit
authors.initials: B
authors.lastname: de Crombrugghe
mesh_terms: D001846:Bone Development / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology*; D019902:Chondrocytes / Q000502:physiology; D010006:Osteoblasts / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: D014157:Transcription Factors