EXPRESSION OF CDK5 (PSSALRE KINASE), A NEURAL CDC2-RELATED PROTEIN-KINASE, IN THE MATURE AND DEVELOPING MOUSE CENTRAL AND PERIPHERAL NERVOUS SYSTEMS

CDK5 is a cdc2-related protein kinase that is known to be highly expre ssed in mature brain. In this study, we obtained a mouse CDK5 cDNA by screening an adult mouse cDNA library. Northern blot analysis demonstr ated that the mouse CDK5 mRNA was expressed especially highly in brain , and moderately in kidney, testis and ovary. In brain the expression of CDK5 is already seen at embryonal 12.5 days (E12.5), and it gradual ly increases through the embryonal stage. After birth, the expression is maintained at a high level to adulthood. In situ hybridization demo nstrated that the expression of CDK5 mRNA was distributed in neurons t hroughout the brain, spinal cord and peripheral ganglia, especially in the hippocampal pyramidal cells, cerebellar Purkinje cells, cortical neurons, olfactory mitral cells, mesencephalic and motor trigeminal nu clei and trigeminal ganglion. In any portion, no apparent expression w as observed in glia. During development, the expression of CDK5 was al ready seen at E12.5 intensely in trigeminal and dorsal root ganglia, a nd moderately and diffusely in the central nervous system. The express ion pattern of CDK5 is quite in contrast with that of CDC2. The fact t hat CDK5 is expressed in terminally differentiated non-dividing neuron s predicts an alternative function(s) in addition to controlling the c ell cycle.