A XENOPUS DISTAL-LESS GENE IN TRANSGENIC MICE - CONSERVED REGULATION IN DISTAL LIMB EPIDERMIS AND OTHER SITES OF EPITHELIAL-MESENCHYMAL INTERACTION

In this paper, we show the conserved regulation of the homeodomain gen e Distal-less-3 (Dlx-3) by analyzing the expression of a promoter from the Xenopus ortholog, Xdll-2, in transgenic mice. A 470-bp frog regul atory sequence confers appropriate expression on a lacZ reporter gene in the ectodermal component of structures derived from epithelial-mese nchymal interactions. Remarkably, this includes structures absent in X enopus, such as the hair follicle and mammary gland, suggesting that c onserved regulatory elements can be used to control the formation of s tructures peculiar to individual species. In addition, expression of D lx-3 in developing limbs is highest at the most distal portion. This p attern is duplicated by the Xenopus promoter, indicating that this DNA may include sequences responsive to conserved proximodistal patternin g signals in the vertebrate limb.