Identification and characterization of protein kinase CK2 as a novel interacting protein of neuronal CDK5 kinase and its functional role in microtubule dynamics

Abstract

In association with its neuron-specific activator p35, Cdk5 plays important roles in various cellular activities in nervous system. In brain, Cdk5/p35 appears to exist as high molecular complexes. Little is known about the regulation of this kinase and aberrant activation of Cdk5 has been implicated in the pathogenesis of several neurodegenerative diseases. Here, we report the identification and characterization of protein kinase CK2 as a novel interacting protein of Cdk5/p35 kinase. CK2 blocks the formation of Cdk5-p35 complex, and thus exerts a direct negative effect on Cdk5 activation by p35. Previous reports showed Cdk5/p35 exists with microtubule in brain and studies have implied that CK2 may be involved in regulating cytoskeleton reorganization. We show that CK2 is a novel microtubule-associated protein which exhibits a potent effect in inducing microtubule assembly and stability. Furthermore, these novel functions of CK2 appear to be independent of its kinase activity.