Abstract
We have isolated the chicken homeobox genesLH-2AandLH-2Bencoding two related LIM domain-containing homeodomain proteins and examined the expression pattern during chick limb development.LH-2Ais most closely related to human and ratLH-2,whileLH-2Bis less conserved. Although bothLH-2AandLH-2Bare expressed in the limb mesenchyme throughout stage 16 to stage 32,LH-2Atranscripts are detectable in the distal limb bud andLH-2Btranscripts are detectable in the anterior limb bud. Signals from the apical ectodermal ridge positively regulateLH-2Aexpression, since removal of the apical ectoderm resulted in the rapid reduction ofLH-2Aexpression in the distal limb mesenchyme. Ectopic expression of thesonic hedgehoggene in the anterior margin of the limb bud resulted in the rapid reduction ofLH-2Bexpression accompanying respecification of the positional value to the posterior phenotype. These results suggest thatLH-2AandLH-2Bplay important roles in the determination and specification of the proximal-distal and anterior-posterior positional values, respectively.
Published Version
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