Degranulation of rat cerebellum induces selective variations in gene expression

Selective variations in the composition of poly(A)-containing mRNA were found to be induced in the rat cerebellum by X-irradiation. mRNA populations prepared from normal and X-irradiated rat cerebella at different stages of their development displayed equal efficiencies when translated in vitro in reticulocyte lysates. Specific differences were revealed, however, when the labeled translation products of both mRNA preparations were subjected to two-dimensional gel electrophoresis followed by fluorography of the dried gels. Of more than 100 polypeptide products, several showed marked intensity differences, indicating changes in the abundance of their directing mRNA species. These differences appear both in developing and in mature cerebellar mRNA, and the extent of modification in mRNA is much higher than the consequent changes in the composition of proteins in the irradiated cerebellum. The degranulation-induced modifications in levels of specific cerebellar mRNA species can be used to identify proteins whose biosynthesis depends on the presence of interneurons.