BCL-2 PROTEIN EXPRESSION IS WIDESPREAD IN THE DEVELOPING NERVOUS-SYSTEM AND RETAINED IN THE ADULT PNS

Cell death is a common feature of neural development in all vertebrate s. The bcl-2 proto-oncogene has been shown to protect a variety of cel l types from programmed cell death. We have examined the distribution of bcl-2 protein in the developing and adult nervous systems. bcl-2 pr otein is widespread during embryonic development. Proliferating neuroe pithelial cells of ventricular zones as well as the postmitotic cells of the cortical plate, cerebellum, hippocampus and spinal cord express bcl-2. Postnatally, bcl-2 is principally retained in the granule cell s of the cerebellum and dentate gyrus of the hippocampus. bcl-2 expres sion in the CNS declines with aging. In the peripheral nervous system, neurons and supporting cells of sympathetic and sensory ganglia-retai n substantial bcl-2 protein throughout life. The widespread expression of bcl-2 in CNS and PNS neurons during embryonic development and its selective retention in the adult PNS is consistent with a role for bcl -2 in regulating neuronal survival. In addition, the expression of bcl -2 in some neuronal populations beyond the recognized period of cell d eath is suggestive of a role for bcl-2 beyond simply protecting neuron s from developmental cell death.