Mouse dac, a novel nuclear factor with homology to Drosophila dachshund shows a dynamic expression in the neural crest, the eye, the neocortex, and the limb bud

Dac is a novel nuclear factor in mouse and humans that shares homology with Drosophila dachshund (dac), Alignment with available sequences defines a c onserved box of 117 amino acids that shares weak homology with the proto-on cogene Ski and Sno, Dac expression is found in various neuroectodermal and mesenchymal tissues. At early developmental stages Dac is expressed in late ral mesoderm and in neural crest cells. In the neural plate/tube Dac expres sion is initially seen in the prosencephalon and gets gradually restricted to the presumptive neocortex and the distal portion of the outgrowing optic vesicle. Furthermore, Dac transcripts are detected in the mesenchyme under lying the Apical Ectodermal Ridge (AER) of the extending limb bud, the dors al root ganglia and chain ganglia, and the mesenchyme of the growing genita lia. Dac expression in the Gli 3 mutant extra toes (Xt/Xt) shows little dif ference compared to the expression in wild-type limb buds. In contrast, a s ignificant expansion of Dac expression are observed in the anterior mesench yme of the limb buds of hemimelic extra toes (Hx/+) mice, FISH analysis rev eals that human DAC maps to chromosome 13q22.3-23 and further fine-mapping defined a position of the DAC gene at 54cM or 13q21.1, a locus that associa tes with mental retardation and skeletal abnormalities. Dev Dyn 1999;214:66 -80. (C) 1999 Wiley-Liss, Inc.