[Differential involvement of PKC subspecies in neuronal function].
Protein kinase C (PKC) is a key enzyme involved in various types of signal transduction, and it is most abundant in the nervous system. Available evidence suggests that PKC plays a prominent role in neuronal transmission. PKC is a member of a family consisting of at least eleven subspecies: alpha, beta I, beta II, gamma, delta, epsilon, eta, theta, mu, zeta and lambda. The individual role of each subspecies could not be demonstrated because of the homologous structure of the PKC subspecies. We studied the distinct functional roles of PKC subspecies in the central nervous system by defining the detailed localization of each subspecies. The immunocytochemical localization suggested that cPKCs (alpha, beta I, beta II, and gamma) function postsynaptically, while epsilon-PKC preferentially modulates the synaptic efficacy in the presynapse. GAP-43, a presynaptic PKC substrate involved in neuronal plasticity, was preferentially phosphorylated by epsilon-PKC rather than alpha, beta and gamma-PKC. As the epsilon-PKC could be activated by arachidonic acid, it is strongly suggested that in the case of LTP, the presynaptic epsilon-PKC is activated by arachidonic acid released postsynaptically and phosphorylates GAP-43, resulting in the increase in glutamate release.
Saito
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Laboratory of Molecular Pharmacology, Kobe University, Japan.
D000818:Animals; D002490:Central Nervous System / Q000201:enzymology; D006801:Humans; D011493:Protein Kinase C / Q000145:classification / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*
D011493:Protein Kinase C