RT Journal Article
SR Electronic
T1 Mesenchymal patterning by <em>Hoxa2</em> requires blocking Fgf-dependent
activation of <em>Ptx1</em>
JF Development
JO Development
FD The Company of Biologists Limited
SP 3403
OP 3414
DO 10.1242/dev.00554
VO 130
IS 15
A1 Bobola, Nicoletta
A1 Carapuço, Marta
A1 Ohnemus, Sabine
A1 Kanzler, Benoît
A1 Leibbrandt, Andreas
A1 Neubüser, Annette
A1 Drouin, Jacques
A1 Mallo, Moisés
YR 2003
UL http://dev.biologists.org/content/130/15/3403.abstract
AB Hox genes are known key regulators of embryonic segmental identity, but little is known about the mechanisms of their action. To address this issue, we have analyzed how Hoxa2 specifies segmental identity in the second branchial arch. Using a subtraction approach, we found that Ptx1 was upregulated in the second arch mesenchyme of Hoxa2 mutants. This upregulation has functional significance because, in Hoxa2-/-;Ptx1-/- embryos, the Hoxa2-/- phenotype is partially reversed. Hoxa2 interferes with the Ptx1 activating process, which is dependent on Fgf signals from the epithelium. Consistently, Lhx6, another target of Fgf8 signaling, is also upregulated in the Hoxa2-/- second arch mesenchyme. Our findings have important implications for the understanding of developmental processes in the branchial area and suggest a novel mechanism for mesenchymal patterning by Hox genes that acts to define the competence of mesenchymal cells to respond to skeletogenic signals.