Phorbol esters modulate spontaneous and Ca2+-evoked transmitter release via acting on both munc13 and protein kinase C
Phorbol esters modulate spontaneous and Ca2+-evoked transmitter release via acting on both munc13 and protein kinase C
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DOI：
10.1523/jneurosci.0550-08.2008
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发表时间：
2008-08-13
影响因子：
5.3
通讯作者：
Schneggenburger, Ralf
中科院分区：
文献类型：
--
作者：
Lou, Xuelin;Korogod, Natalya;Schneggenburger, Ralf
二酰基甘油（DAG）和佛波醇酯通过激活蛋白激酶C（PKC）和突触前囊泡引发蛋白的Munc 13家族成员而强烈增强突触处的递质释放。这种PKC/Munc 13途径已经成为释放概率的关键调节剂，在各种形式的活性依赖性释放增强过程中。在这里，我们研究了PKC和Munc 13 -1在佛波酯增强的诱发和自发的递质释放在萼的Held突触的相对作用。佛波酯佛波12，13-二丁酸酯（1 μ M）增强了微型EPSC的频率，并以类似的时间过程诱发EPSC的幅度。预孵育片与PKC阻断剂Ro 31 -82200降低了增强，主要是通过影响后期的佛波酯增强。Ro 31 -8220不敏感的增强作用最有可能是由Munc 13 -1介导的，因为在Munc 13 - 1H 567 K基因敲入小鼠的器官型切片中，其中DAG与Munc 13 -1的结合被消除，佛波酯自发释放的增强作用被强烈抑制。使用直接突触前去极化配对记录，我们表明，佛波酯增强不去沿着增加的数量容易释放囊泡，尽管在100 Hz的刺激列车的累积EPSC振幅增加。我们的数据表明，Munc 13和PKC的激活都有助于增强易释放囊泡的融合概率。因此，对接和容易释放的囊泡是通过细胞内第二信使途径，通过Munc 13和PKC作用的调制基板。
Diacylglycerol (DAG) and phorbol esters strongly potentiate transmitter release at synapses by activating protein kinase C (PKC) and members of the Munc13 family of presynaptic vesicle priming proteins. This PKC/Munc13 pathway has emerged as a crucial regulator of release probability during various forms of activity-dependent enhancement of release. Here, we investigated the relative roles of PKC and Munc13-1 in the phorbol ester potentiation of evoked and spontaneous transmitter release at the calyx of Held synapse. The phorbol ester phorbol 12,13-dibutyrate (1 mu M) potentiated the frequency of miniature EPSCs, and the amplitudes of evoked EPSCs with a similar time course. Preincubating slices with the PKC blocker Ro31-82200 reduced the potentiation, mainly by affecting a late phase of the phorbol ester potentiation. The Ro31-8220-insensitive potentiation was most likely mediated by Munc13-1, because in organotypic slices of Munc13-1H567K knock-in mice, in which DAG binding to Munc13-1 is abolished, the potentiation of spontaneous release by phorbol ester was strongly suppressed. Using direct presynaptic depolarizations in paired recordings, we show that the phorbol ester potentiation does not go along with an increase in the number of readily releasable vesicles, despite an increase in the cumulative EPSC amplitude during 100 Hz stimulation trains. Our data indicate that activation of Munc13 and PKC both contribute to an enhancement of the fusion probability of readily releasable vesicles. Thus, docked and readily releasable vesicles are a substrate for modulation via intracellular second-messenger pathways that act via Munc13 and PKC.