| First Author | Takarada T | Year | 2013 |
| Journal | J Bone Miner Res | Volume | 28 |
| Issue | 10 | Pages | 2064-9 |
| PubMed ID | 23553905 | Mgi Jnum | J:210124 |
| Mgi Id | MGI:5569585 | Doi | 10.1002/jbmr.1945 |
| Citation | Takarada T, et al. (2013) An analysis of skeletal development in osteoblast-specific and chondrocyte-specific runt-related transcription factor-2 (Runx2) knockout mice. J Bone Miner Res 28(10):2064-9 |
| abstractText | Global gene deletion studies in mice and humans have established the pivotal role of runt related transcription factor-2 (Runx2) in both intramembranous and endochondral ossification processes during skeletogenesis. In this study, we for the first time generated mice carrying a conditional Runx2 allele with exon 4, which encodes the Runt domain, flanked by loxP sites. These mice were crossed with alpha1(I)-collagen-Cre or alpha1(II)-collagen-Cre transgenic mice to obtain osteoblast-specific or chondrocyte-specific Runx2 deficient mice, respectively. As seen in Runx2(-/-) mice, perinatal lethality was observed in alpha1(II)-Cre;Runx2(flox/flox) mice, but this was not the case in animals in which alpha1(I)-collagen-Cre was used to delete Runx2. When using double-staining with Alizarin red for mineralized matrix and Alcian blue for cartilaginous matrix, we observed previously that mineralization was totally absent at embryonic day 15.5 (E15.5) throughout the body in Runx2(-/-) mice, but was found in areas undergoing intramembranous ossification such as skull and clavicles in alpha1(II)-Cre;Runx2(flox/flox) mice. In newborn alpha1(II)-Cre;Runx2(flox/flox) mice, mineralization impairment was restricted to skeletal areas undergoing endochondral ossification including long bones and vertebrae. In contrast, no apparent skeletal abnormalities were seen in mutant embryo, newborn, and 3-week-old to 6-week old-mice in which Runx2 had been deleted with the alpha1(I)-collagen-Cre driver. These results suggest that Runx2 is absolutely required for endochondral ossification during embryonic and postnatal skeletogenesis, but that disrupting its expression in already committed osteoblasts as achieved here with the alpha1(I)-collagen-Cre driver does not affect overtly intramembranous and endochondral ossification. The Runx2 floxed allele established here is undoubtedly useful for investigating the role of Runx2 in particular cells. |
