Abstract
Cyclin-denpendent kinase 5 (Cdk5) is a serine/threonine kinase with close structural homology to the Cdks. Cdk5 forms a complex with its activators, p35 or p39. Previous studies have shown that both p35 and p39 are only expressed in neuron, and Cdk5/p35 has important roles in the regulation of neuronal functions such as coricogenesis and fasciculation of the axon fibers. Moreover, recent studies have revealed that Cdk5/p35 is involved in neurotransmitter release. Cdk5/p35 phosphorylates many synaptic proteins such as P/Q- type voltage-dependent calcium channel (P/Q-type VDCC), Dynamin 1 and Amphiphysin 1. Phosphorylation of P/Q-type VDCC by Cdk5 suppresses neurotransmitter release by downregulation of its channel activity. These previous observations strongly suggest that Cdk5/p35 has an important role in the regulation of neurotransmission. It is known that the secretion of insulin in pancreatic islets has a similar mechanism with neurotransmitter releasing. However, the expression level of Cdk5/p35 and its physiological functions during the secretion of insulin are unknown. In order to investigate the role of Cdk5/p35 in islets, we examined the expression of Cdk5/p35 in isolated islets and β-cell line MIN6. [Jpn J Physiol 54 Suppl:S220 (2004)]
