307-BP FRAGMENT IN HOXA7 UPSTREAM SEQUENCE IS SUFFICIENT FOR ANTERIORBOUNDARY FORMATION

The HOX genes are expressed in a positionally and temporally restricte d manner involving anteroposterior axial pattern formation during earl y embryogenesis. Previously, we studied the sequence and function of a n upstream regulatory region of the human HOXA7 gene. To identify a cr itical cis-acting element, a deletion analysis was performed along the human control region (HCR) (about 1.1 kb), which was sufficient for s etting the anterior boundary of expression in transgenic mice. We demo nstrated that a 307-bp control region contains a cis-acting element(s) specifying an anterior boundary as well as a dorsal-ventral restricti on in the neural tube at day 12.5 postconception (p.c.). The distinct anterior limit of expression was noted at the level of C7/T1 in the ne ural tube and spinal ganglia, In addition, our deletion experiments re vealed that the HCR consisted of several cis-acting elements which wer e individually capable of driving regionally restricted expression pat terns in the neural tube and limb buds.