The novel zinc finger-containing transcription factor osterix is required for osteoblast differentiation and bone formation.
We have identified a novel zinc finger-containing transcription factor, called Osterix (Osx), that is specifically expressed in all developing bones. In Osx null mice, no bone formation occurs. In endochondral skeletal elements of Osx null mice, mesenchymal cells, together with osteoclasts and blood vessels, invade the mineralized cartilage matrix. However, the mesenchymal cells do not deposit bone matrix. Similarly, cells in the periosteum and in the condensed mesenchyme of membranous skeletal elements cannot differentiate into osteoblasts. These cells do, however, express Runx2/Cbfa1, another transcription factor required for bone formation. In contrast, Osx is not expressed in Runx2/Cbfa1 null mice. Thus, Osx acts downstream of Runx2/Cbfa1. Because Osx null preosteoblasts express typical chondrocyte marker genes, we propose that Runx2/Cbfa1-expressing preosteoblasts are still bipotential cells.
Nakashima
Kazuhisa
K
Department of Molecular Genetics and Program in Genes and Development, M. D. Anderson Cancer Center, University of Texas, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
Zhou
Xin
X
Kunkel
Gary
G
Zhang
Zhaoping
Z
Deng
Jian Min
JM
Behringer
Richard R
RR
de Crombrugghe
Benoit
B
D000818:Animals; D015415:Biomarkers; D002454:Cell Differentiation / Q000502:physiology; D019902:Chondrocytes / Q000166:cytology; D050659:Core Binding Factor Alpha 1 Subunit; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D010006:Osteoblasts / Q000166:cytology*; D010010:Osteoclasts / Q000166:cytology; D010012:Osteogenesis / Q000502:physiology*; D011994:Recombinant Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D016335:Zinc Fingers / Q000235:genetics*
D015415:Biomarkers; D050659:Core Binding Factor Alpha 1 Subunit; D009363:Neoplasm Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors