MASSIVE CELL-DEATH OF IMMATURE HEMATOPOIETIC-CELLS AND NEURONS IN BCL-X-DEFICIENT MICE

bcl-x is a member of the bcl-2 gene family, which may regulate program med cell death. Mice were generated that lacked Bcl-x. The Bcl-x-defic ient mice died around embryonic day 13. Extensive apoptotic cell death was evident in postmitotic immature neurons of the developing brain, spinal cord, and dorsal root ganglia. Hematopoietic cells in the liver were also apoptotic. Analyses of bcl-x double-knockout chimeric mice showed that the maturation of Bcl-x-deficient lymphocytes was diminish ed. The life-span of immature lymphocytes, but not mature lymphocytes, was shortened. Thus, Bcl-x functions to support the viability of imma ture cells during the development oi the nervous and hematopoietic sys tems.