Homeobox Protein D1 (HOXD1)

HOXD1 is a member of the Antp homeobox family and encodes a protein with a homeobox DNA-binding domain. This nuclear protein functions as a sequence-specific transcription factor that is involved in differentiation and limb development. Mutations in this gene have been associated with severe developmental defects on the anterior-posterior (a-p) limb axis.

This mechanism appeared to depend upon Notch signaling, as mice deficient for Rbpjk, the effector of the Notch pathway, showed severely reduced Hoxd gene expression in presomitic mesoderm. These results suggested a molecular link between Hox gene activation and the segmentation clock. Such a linkage would efficiently keep in phase the production of novel segments with their morphologic specification.