Hox Genes and Spinal Cord Development

The spinal cord is differentiated along the rostrocaudal axis into large domains with regional distinctions reflected in the position and projection of specific cell types. Spinal cord patterning is likely to be mediated by the local expression and activity of transcription factors. This review will examine the expression of one class of transcription factors, encoded by the Hox genes, that are active in spinal cord patterning. Hox genes encode homeodomain-containing proteins with overlapping rostrocaudal domains of expression in the developing spinal cord. Rostrally expressed Ant-p/Ubx/Abd-D-related Hox genes may function in patterning the cervical spinal cord, while Abd-D-related, caudally expressed Hox genes may pattern the lumbar spinal cord. Changes in spinal cord patterning are apparent following Hox gene inactivation, supporting a role for these genes in defining or establishing this pattern.