High expression of Bcl-x protein in the developing human cerebellar cortex.

The gene bcl-x, which is related to a bcl-2, regulates programmed cell death. bcl-x may function in the development of the nervous system. We raised a polyclonal antibody against human Bcl-x protein, and investigated its distribution in the developing human cerebellum. Western blotting revealed that Bcl-x expression in the cerebellum is higher in the fetal, than in the postnatal period. Immunohistochemical studies of fetal brains localized intense Bcl-x immunoreactivity in the granule cell processes at 13-22 gestational weeks and in the Purkinje cell bodies at 24-38 weeks. The immunoreactivity decreased after birth, but was retained in the Purkinje cells at a low level until adulthood. These results suggested that Bcl-x expression in the cerebellum is developmentally regulated and involved specifically in the development of neuronal subpopulations.