Localization of the HoxB5 protein in the developing CNS of late gestational mouse embryos.

We cloned a full-length HoxB5 cDNA from the human neuroblastoma cell line, SHSY5Y, and used it to raise specific antibodies against a divergent domain of its protein. The antibodies then were used to immunolocalize and determine the expression pattern of the HoxB5 homeodomain protein in the late gestational mouse embryos. With particular reference to the structures of the developing nervous system, relatively high levels of the HoxB5 protein were detected in 15- and 18-day-old gestational mouse embryos. Expression domains were similar in both stages and were limited almost exclusively to the central nervous system. Expression of the HoxB5 protein was found in areas that extended from the rostral medulla oblongata to the caudal parts of the spinal cord. In all regions of the CNS, expression levels were higher in the rostral and ventral regions compared to the caudal and dorsal areas, respectively. These findings suggest that the function of the HoxB5 protein is not limited to the early stages of neural development and extends into later stages as well. These findings suggest also that the HoxB5 protein may play a role in the organization of the neural structures along both of the dorsoventral and craniocaudal axes of the developing fetus in vertebrate species.