Hox targeting in vertebrate forelimb induction: Expression and comparative genomics.

摘要

Hox genes encode master regulators of body plan during embryonic development. In land and avian (bird) vertebrates there are four clusters of Hox genes (A, B, C, D). Patterns of Hox expression (paralogs 5-8), in our work specifically Hoxc5, c6, c8, and Hoxd8 in the forelimb forelimb area have been determined, using the chicken (Gallus gallus) as our model organism. These data help complete the known Hox gene expression patterns for early forelimb development for all four land and avian vertebrates. Potential Hox, Hox-associated, and homeodornain core binding sites in genes inducing the forelimb (Tbx5, Sall1, Sall4, and Fgf10) have been predicted through comparative genomics, including the use of sequence alignment, phylogenetic footprinting, and related analyses. We have also used comparative genomics to predict potential Lmx1b core binding sites in the Emx2 gene. Both Lmx1b and Emx2 are factors involved in forelimb and shoulder girdle dorsalization.