| First Author | Kanzler B | Year | 1998 |
| Journal | Development | Volume | 125 |
| Issue | 14 | Pages | 2587-97 |
| PubMed ID | 9636074 | Mgi Jnum | J:49163 |
| Mgi Id | MGI:1276793 | Doi | 10.1242/dev.125.14.2587 |
| Citation | Kanzler B, et al. (1998) Hoxa-2 restricts the chondrogenic domain and inhibits bone formation during development of the branchial area. Development 125(14):2587-97 |
| abstractText | In Hoxa-2(-/- )embryos, the normal skeletal elements of the second branchial arch are replaced by a duplicated set of first arch elements. We show here that Hoxa-2 directs proper skeletal formation in the second arch by preventing chondrogenesis and intramembranous ossification. In normal embryos, Hoxa-2 is expressed throughout the second arch mesenchyme, but is excluded from the chondrogenic condensations. In the absence of Hoxa-2, chondrogenesis is activated ectopically within the rostral Hoxa-2 expression domain to form the mutant set of cartilages. In Hoxa-2(-/-) embryos the Sox9 expression domain is shifted into the normal Hoxa-2 domain. Misexpression of Sox9 in this area produces a phenotype resembling that of the Hoxa-2 mutants. These results indicate that Hoxa-2 acts at early stages of the chondrogenic pathway, upstream of Sox9 induction. We also show that Hoxa-2 inhibits dermal bone formation when misexpressed in its precursors. Furthermore, molecular analyses indicate that Cbfa1 is upregulated in the second branchial arches of Hoxa-2 mutant embryos suggesting that prevention of Cbfa1 induction might mediate Hoxa-2 inhibition of dermal bone formation during normal second arch development. The implications of these results on the patterning of the branchial area are discussed. |
