Two types of Ca2+channel linked to two endocytic pathways coordinately maintain synaptic transmission at the Drosophila synapse
Two types of Ca2+channel linked to two endocytic pathways coordinately maintain synaptic transmission at the Drosophila synapse
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DOI：
10.1111/j.1460-9568.2010.07300.x
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发表时间：
2010-08-01
影响因子：
3.4
通讯作者：
Kidokoro, Y.
中科院分区：
文献类型：
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作者：
Kuromi, H.;Ueno, K.;Kidokoro, Y.
突触前末端的内吞作用是由电压门控钙通道的钙离子内流引起的。在果蝇神经肌肉接头处，我们展示了两种内吞作用成分，它们与不同的钙通道相连。电压门控性钙通道阻断剂(R)-(+)-Bay K8644(R-bayk)选择性地阻断一种成分(R-bayk敏感成分)而不影响胞吐作用，而低浓度La3+优先抑制另一种成分(La3+敏感成分)。在温度敏感突变体shibirets中，在不允许的温度下，在对R-bayk敏感的内吞作用中，在活动区(AZ)发现了Dynamin簇，而在La3+敏感的内吞作用中，在非AZ区检测到了它们。钙通道α(2)α(2)β亚基编码在AZ内，并且stj突变抑制了R-bayk敏感成分，但增强了La3+敏感成分，表明α(2)Delta亚基与R-bayk敏感的钙通道有关。Filipin结合在非偶氮层膜上，对La3+敏感成分有抑制作用，但对R-bayk敏感成分无抑制作用。我们的结论是，R-bayk敏感的内吞作用发生在AZ区，并称之为AZ内吞作用。我们还得出结论，La3+敏感成分发生在非AZ区，并称之为非AZ内吞作用。这两种类型的内吞作用都被不同的药物朝着相反的方向调节，表明它们是不同的调节方式。在高频刺激时，AZ内吞作用主要发生在早期，而非AZ内吞作用主要发生在晚期。因此，强烈的突触传递是由两种类型的钙离子通道中的钙离子内流启动的突触小泡循环所协调维持的。
Endocytosis at the presynaptic terminal is initiated by Ca2+ influx through voltage-gated Ca2+ channels. At the Drosophila neuromuscular junction, we demonstrated two components of endocytosis linked to distinct Ca2+ channels. A voltage-gated Ca2+ channel blocker, (R)-(+)-Bay K8644 (R-BayK), selectively blocked one component (R-BayK-sensitive component) without affecting exocytosis, while low concentrations of La3+ preferentially depressed the other component (La3+ -sensitive component). In a temperature-sensitive mutant, shibirets, at non-permissive temperatures, dynamin clusters were found immunohistochemically at the active zone (AZ) during the R-BayK-sensitive endocytosis, while they were detected at the non-AZ during the La3+-sensitive endocytosis. Immunostaining of the Ca2+ channel alpha(2)delta subunit encoded by straightjacket (stj) was found within the AZ, and a mutation in stj depressed the R-BayK-sensitive component but enhanced the La3+ -sensitive one, indicating that the alpha(2)delta subunit is associated with the R-BayK-sensitive Ca2+ channel. Filipin bound to the non-AZ membrane and inhibited the La3+ -sensitive component, but not the R-BayK-sensitive one. We concluded that the R-BayK-sensitive component of endocytosis occurred at the AZ and termed this AZ endocytosis. We also concluded that the La3+ -sensitive component occurred at the non-AZ and termed this non-AZ endocytosis. These two types of endocytosis were modulated by various drugs towards opposite directions, indicating that they were differentially regulated. During high-frequency stimulation, AZ endocytosis operated mainly in the early phase, whereas non-AZ endocytosis operated in the late phase. Thus, intense synaptic transmission is coordinately maintained by synaptic vesicle recycling initiated by Ca2+ influx through the two types of Ca2+ channel.