title: TWIST inactivation reduces CBFA1/RUNX2 expression and DNA binding to the osteocalcin promoter in osteoblasts.
abstract: The Saethre-Chotzen (SC) syndrome is characterized by increased osteogenesis and premature fusion of cranial sutures, resulting from mutations in TWIST, a basic helix-loop-helix transcription factor. The molecular target genes for Twist in osteoblasts are however unknown. We report here that TWIST haploinsufficiency in mutant osteoblasts reduces mRNA and protein levels for CBFA1/RUNX2, a specific osteoblast transcription factor, during both osteoblast cell growth and in vitro osteogenesis. Moreover, this is associated with altered expression of major osteoblast-specific genes. Electrophoretic mobility shift assay (EMSA) showed reduced-binding ability of Cbfa1 to its target OSE2 element in the osteocalcin promoter in mutant osteoblasts. By contrast, TWIST inactivation does not hamper Cbfa1 binding on a similar upstream element present in the alpha1(I) collagen promoter in mutant osteoblasts. This provides the first evidence that TWIST inactivation alters CBFA1/RUNX2 expression and Cbfa1 binding ability to the osteocalcin promoter, indicating that CBFA1/RUNX2 is a target gene for TWIST in human osteoblasts.
authors.affiliation: INSERM Unit 349 Affiliated CNRS, Lariboisière Hospital, 2 rue Ambroise Paré, 75475 10, Paris Cedex, France
authors.forename: Malika
authors.initials: M
authors.lastname: Yousfi
authors.forename: Françoise
authors.initials: F
authors.lastname: Lasmoles
authors.forename: Pierre J
authors.initials: PJ
authors.lastname: Marie
mesh_terms: D000168:Acrocephalosyndactylia / Q000235:genetics*; D019943:Amino Acid Substitution; D001483:Base Sequence; D050659:Core Binding Factor Alpha 1 Subunit; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D007223:Infant; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010006:Osteoblasts / Q000378:metabolism*; D015675:Osteocalcin / Q000235:genetics*; D010012:Osteogenesis; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012886:Skull / Q000002:abnormalities; D014157:Transcription Factors / Q000235:genetics*; D051879:Twist-Related Protein 1
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D017931:DNA Primers; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; C103173:TWIST1 protein, human; D014157:Transcription Factors; D051879:Twist-Related Protein 1; D015675:Osteocalcin