DEFORMED AUTOREGULATORY ELEMENT FROM DROSOPHILA FUNCTIONS IN A CONSERVED MANNER IN TRANSGENIC MICE

THE striking similarities in the structure, organization and anterior-posterior expression patterns between the murine Hox gene system and the Drosophila homeotic gene complexes1,2, called HOM-C (ref. 3), may point to highly conserved mechanisms for specifying positional identities (reviewed in ref. 4). Strong support for this concept lies in the observation of conserved colinearity between the genomic order of the Hox/HOM genes and their unique successive expression domains along the anterior-posterior axes of both mouse and fly embryos1,2. These unique and precise expression patterns appear to be facilitated by multiple cis-regulatory elements (reviewed in ref. 5). One of the few elements characterized in detail is the autoregulatory enhancer of the homeotic gene Deformed (Dfd)6-9, which supports expression in subregions of posterior head segments of Drosophila embryos7. Here we present evidence that this enhancer is capable of conferring reporter gene expression to a discrete subregion of the hindbrain in transgenic mouse embryos. Remarkably, this anterior-posterior subregion lies within the common anterior expression domain of the Dfd cognate Hox genes in the postotic hindbrain10,11. Our results indicate that the Dfd autoregulatory enhancer is part of a highly conserved mechanism for establishing region-specific gene expression along the anterior-posterior axis of the embryo.