title: Genetic analysis of Runx2 function during intramembranous ossification.
abstract: Runt-related transcription factor 2 (Runx2) is an essential transcriptional regulator of osteoblast differentiation and its haploinsufficiency leads to cleidocranial dysplasia because of a defect in osteoblast differentiation during bone formation through intramembranous ossification. The cellular origin and essential period for Runx2 function during osteoblast differentiation in intramembranous ossification remain poorly understood. Paired related homeobox 1 (Prx1) is expressed in craniofacial mesenchyme, and Runx2 deficiency in cells of the Prx1 lineage (in mice referred to here as Runx2prx1 (-/-)) resulted in defective intramembranous ossification. Runx2 was heterogeneously expressed in Prx1-GFP(+) cells located at the intrasutural mesenchyme in the calvaria of transgenic mice expressing GFP under the control of the Prx1 promoter. Double-positive cells for Prx1-GFP and stem cell antigen-1 (Sca1) (Prx1(+)Sca1(+) cells) in the calvaria expressed Runx2 at lower levels and were more homogeneous and primitive than Prx1(+)Sca1(-) cells. Osterix (Osx) is another transcriptional determinant of osteoblast lineages expressed by osteoblast precursors; Osx is highly expressed by Prx1(-)Runx2(+) cells at the osteogenic front and on the surface of mineralized bone in the calvaria. Runx2 deficiency in cells of the Osx lineage (in mice referred to here as Runx2osx (-/-)) resulted in severe defects in intramembranous ossification. These findings indicate that the essential period of Runx2 function in intramembranous ossification begins at the Prx1(+)Sca1(+) mesenchymal stem cell stage and ends at the Osx(+)Prx1(-)Sca1(-) osteoblast precursor stage.
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan takarada@p.kanazawa-u.ac.jp hinoi@p.kanazawa-u.ac.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takarada
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Nakazato
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Azusa
authors.initials: A
authors.lastname: Tsuchikane
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Fujikawa
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Iezaki
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yoneda
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa 920-1192, Japan takarada@p.kanazawa-u.ac.jp hinoi@p.kanazawa-u.ac.jp.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Hinoi
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000818:Animals; D000067696:Ataxin-1 / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D064231:Nestin / Q000235:genetics / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010012:Osteogenesis / Q000235:genetics / Q000502:physiology; D012886:Skull / Q000166:cytology / Q000378:metabolism; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000067696:Ataxin-1; C000593750:Atxn1 protein, mouse; D050659:Core Binding Factor Alpha 1 Subunit; D018398:Homeodomain Proteins; D064231:Nestin; C489936:Prrx1 protein, mouse; C493716:Runx2 protein, mouse; D000076182:Sp7 Transcription Factor; C479466:Sp7 protein, mouse; D014157:Transcription Factors
keywords: Mouse; Nestin; Osteoblast; Osterix; Prx1; Runx2