Comparative cis-regulatory analyses identify new elements of the mouse Hoxc8 early enhancer.

The Hoxc8 early enhancer is a 200 bp region that controls the early phase of Hoxc8 expression during mouse embryonic development. This enhancer defines the domain of Hoxc8 expression in the neural tube and mesoderm of the posterior regions of the developing embryo. Five distinct cis-acting elements, A-E, were previously shown to govern early phase Hoxc8 expression.

Divergence of Hoxc8 early enhancer parallels diverged axial morphologies between mammals and fishes.

There is considerable interest in understanding how cis-regulatory modifications drive morphological changes across species. Because developmental regulatory genes, including Hox genes, are remarkably conserved, their noncoding regulatory regions are likely sources for variations. Modifications of Hox cis-regulatory elements have potential to alter Hox gene expression and, hence, axial morphologies.