CYTOPLASMIC CREB-ALPHA-LIKE ANTIGENS IN SPECIFIC REGIONS OF THE RAT-BRAIN

We have investigated the expression of the alpha-region of CREB (amino acids 88-101) in the rat brain. This region is encoded by a separate exon and has been reported to enhance the transcriptional efficiency o f CREB. Light microscopic immunohistochemistry showed labeled neurons in several brain regions, such as the spinal cord, pontine reticular f ormation, cerebellum, hypothalamus, hippocampus and olfactory cortex. The labeling was exclusively cytoplasmic, and electron microscopy reve aled that the CREB alpha-immunoreactivity was localized to the Golgi a pparatus and axon terminals. Immunoblotting after SDS-PAGE showed spec ifically detected proteins of 21 and 160 kD. We suggest that neuronal CREB alpha-proteins represent alternatively spliced isoforms of CREB t hat lack the nuclear translocation signal. These isoforms may be invol ved in the regulation of CREB-mediated transcription. (C) 1996 Academi c Press, Inc.