Expression of the 2',3'-cyclic nucleotide 3'-phosphohydrolase gene and immunoreactive protein in oligodendrocytes as revealed by in situ hybridization and immunofluorescence.

In order to investigate the role of the myelin-associated enzyme 2' 3'-cyclic nucleotide 3'-phosphohydrolase in the development of the myelin sheath, as well as genetic factors involving dysmyelinating disorders, we have recently isolated and sequenced cDNAs corresponding to the CNPase protein. In this study we have used 32P-labeled bovine CNPase cDNA probes to localize the messenger RNA coding for this enzyme in mouse cerebral and cerebellar cryostat sections and have compared our data with the distribution of the CNPase protein as revealed by immunofluorescence. Specific labeling was localized to the white matter fiber tracts and, in many areas, to individual oligodendrocyte cell bodies. The corpus callosum and the white matter of the cerebellum were heavily labeled. Distribution of the CNPase protein, as detected by immunohistochemical studies, was parallel to that of the CNPase mRNA as detected by in situ hybridization histochemistry, with oligodendrocyte cell bodies and their processes intensely labeled. This study provides strong evidence that the CNPase gene is expressed in the myelin-producing cells of the central nervous system and that CNPase is synthesized by and stored within oligodendrocytes.