期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2001
卷号：98
期号：24
页码：14017-14021
DOI：10.1073/pnas.241333598
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Activation of protein kinase C (PKC) by phorbol ester facilitates hormonal secretion and transmitter release, and phorbol ester-induced synaptic potentiation (PESP) is a model for presynaptic facilitation. A variety of PKC isoforms are expressed in the central nervous system, but the isoform involved in the PESP has not been identified. To address this question, we have applied immunocytochemical and electrophysiological techniques to the calyx of Held synapse in the medial nucleus of the trapezoid body (MNTB) of rat auditory brainstem. Western blot analysis indicated that both the Ca2+-dependent "conventional" PKC and Ca2+-independent "novel" PKC isoforms are expressed in the MNTB. Denervation of afferent fibers followed by organotypic culture, however, selectively decreased "novel" {varepsilon}PKC isoform expressed in this region. The afferent calyx terminal was clearly labeled with the {varepsilon}PKC immunofluorescence. On stimulation with phorbol ester, presynaptic {varepsilon}PKC underwent autophosphorylation and unidirectional translocation toward the synaptic side. Chelating presynaptic Ca2+, by using membrane permeable EGTA analogue or high concentration of EGTA directly loaded into calyceal terminals, had only a minor attenuating effect on the PESP. We conclude that the Ca2+-independent {varepsilon}PKC isoform mediates the PESP at this mammalian central nervous system synapse.
