Cloning, characterization, and mapping of the mouse homeobox gene Hmx1

Homeobox-containing genes play an important role in development, including positional specification of the body plan and organogenesis. We previously isolated the human HMX1 (H6) gene, a novel homeobox-containing gene of the HMX family, from a human embryonic craniofacial cDNA library. The closely related mouse genes Hmx3 (Nkx5.1) and Hmx2 (Nkx5.2) are in the same class as the HMX1 gene and are expressed in the craniofacial region of the developing embryo. To provide a resource for further characterization of the human HMX1 gene, we isolated the mouse Hmx1 genomic clone. We show here the mouse Hmx1 genomic sequence, its gene mapping, and its expression pattern in the developing mouse embryo. Evidence is presented showing that the three known Hmx genes in the mouse likely play complementary roles in the development of the second arch, retina, sympathetic nerve ganglia, and cranial neural ganglia. Hmx1 may play an important role in the development of craniofacial structures and may interact with Hoxa-2 and Dlx-2 in the second branchial arch.