Developmental alternation of the expression and kinase activity of Cyclin-dependent kinase (Cdk)5/P35^nck5a in the rat retina

Purpose. Previous reports have reported the expression and kinase activity of Cdk5/ P35^nck5a in the brains. However, the expression, the exact cellular localization, and kinase activity of Cdk5/P35^nck5a in retina have not been elucidated. In this study, we examined the localization and kinase activity in the developing rat retina. Methods. Western blot analysis, immunohistochemistry and kinase activity at 1week, 2weeks, 3weeks after birth and adult of the rat retina were performed. Results. Cdk5 expression was increased from 1 to 3 weeks after birth, and then decreased. The developmental changes in P35^nck5a expression correlated with the changes in Cdk5 expression. Immunohistochemical study showed that Cdk5 was expressed in the ganglion cells (GC) and some cells of the inner nuclear layer (INL) at 1 week after birth. At 2 weeks after birth, it was expressed in the inner plexiform layer (IPL) in addition. In the adult retina, Cdk5 expressed in the IPL and some cells in the INL. P35^nck5a was expressed in the GC and some cells of the INL in 1-3 weeks after birth models. At 3 weeks after birth, P35^nck5a was strongly detected in the photoreceptor inner segment. In the adult retina, it was seen only in the GC. Conclusions. Immunohistochemical changes of the localization of Cdk5 in the developing retina was similar to the B50/GAP43. Therefore, it may be suggested that Cdk5/P35^nck5a play a role of neuronal plasticity.