MouseAlx3:Anaristaless-like Homeobox Gene Expressed during Embryogenesis in Ectomesenchyme and Lateral Plate Mesoderm

Abstract

MouseAlx3is a homeobox gene that is related to theDrosophila aristalessgene and to a group of vertebrate genes includingPrx1, Prx2, Cart1,andAlx4.The protein encoded contains a diverged variant of a conserved peptide sequence present near the carboxyl terminus of at least 15 different paired-class-homeodomain proteins.Alx3is expressed in mouse embryos from 8 days of gestation onward in a characteristic pattern, predominantly in neural crest-derived mesenchyme and in lateral plate mesoderm. We detected prominent expression in frontonasal head mesenchyme and in the first and second pharyngeal arches and some of their derivatives. High expression was also seen in the tail and in many derivatives of the lateral plate mesoderm including the limbs, the body wall, and the genital tubercle. aristaless-related genes likeAlx3, Cart1,andPrx2are expressed in overlapping proximodistal patterns in the pharyngeal arches. Similar, but more lateral patterns have been described for theDistal-less-related (Dlx) genes. Intriguingly, expression and to some extent function ofaristalessandDistal-lessinDrosophilaalso have overlapping as well as complementary aspects.Alx3was localized to chromosome 3, near the droopy-ear (de) mutation.