Fig. 8. A model for the mechanism of jaw patterning by Dlx genes.
In BA1 mesenchyme, Dlx5/6 are only expressed in mdBA1, whereas Dlx1/2 are expressed in both mdBA1 and mxBA1. Dlx5/6 induce and/or maintain expression of Group A genes (Dlx3, Dlx4, Hand1, Hand2, Gbx2, Gsc, Alx3, Alx4, Bmper, Cited1, Zac1, Unc5c, Hgf, Rgs5, A/S Dlx1 and Evf1/2) in mdBA1, while repressing Group B (Pou3f3, 2610016I09Rik and 2900092D14Rik) and Group C (Foxl2, E330015D05Rik, Cyp26a1 and Irx5) genes so that their expression is mostly confined to mxBA1. Dlx1/2 induce and/or maintain Group B genes in mxBA1. By contrast, in mdBA1, Dlx1/2 induce and/or maintain Group A genes and repress Group B genes. Presumably, Group A genes promote lower jaw development, whereas Group B and Group C genes promote upper jaw development.