Structural domains involved in the regulation of transmitter release by synapsins
Structural domains involved in the regulation of transmitter release by synapsins
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DOI：
10.1523/jneurosci.4278-04.2005
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发表时间：
2005-03-09
影响因子：
5.3
通讯作者：
Greengard, P
中科院分区：
文献类型：
--
作者：
Hilfiker, S;Benfenati, F;Greengard, P
突触蛋白是一类神经元特异性磷酸化蛋白，通过与突触囊泡结合来调节神经递质的释放。突触蛋白由一系列保守的、功能未知的可变结构域组成。我们进行了一个系统的结构功能分析的各个领域的突触蛋白通过评估突触蛋白片段的神经递质释放，突触前超微结构和突触蛋白的生化相互作用的行动。将A域衍生的肽注射到鱿鱼巨大的突触前末梢以磷酸化依赖的方式抑制神经递质的释放。这种肽对囊泡池大小、突触抑制或递质释放动力学没有影响。相反，来自结构域C的肽片段减少了活性区外围的突触囊泡的数量，并增加了突触抑制的速率和程度。这种肽也减缓了神经递质释放的动力学，而不影响停靠囊泡的数量。结构域C肽，以及另一种肽从结构域E，已知具有相同的影响囊泡池的大小和释放动力学，都专门干扰突触蛋白结合肌动蛋白，但不与突触蛋白结合突触囊泡。这表明这两种肽通过阻止突触蛋白与肌动蛋白的相互作用来干扰释放。因此，结构域C和E与肌动蛋白细胞骨架的相互作用可能允许突触蛋白在调节释放中发挥两种作用，而结构域A具有以磷酸化敏感的方式调节递质释放的肌动蛋白独立功能。
Synapsins are a family of neuron-specific phosphoproteins that regulate neurotransmitter release by associating with synaptic vesicles. Synapsins consist of a series of conserved and variable structural domains of unknown function. We performed a systematic structure function analysis of the various domains of synapsin by assessing the actions of synapsin fragments on neurotransmitter release, presynaptic ultrastructure, and the biochemical interactions of synapsin. Injecting a peptide derived from domain A into the squid giant presynaptic terminal inhibited neurotransmitter release in a phosphorylation-dependent manner. This peptide had no effect on vesicle pool size, synaptic depression, or transmitter release kinetics. In contrast, a peptide fragment from domain C reduced the number of synaptic vesicles in the periphery of the active zone and increased the rate and extent of synaptic depression. This peptide also slowed the kinetics of neurotransmitter release without affecting the number of docked vesicles. The domain C peptide, as well as another peptide from domain E that is known to have identical effects on vesicle pool size and release kinetics, both specifically interfered with the binding of synapsins to actin but not with the binding of synapsins to synaptic vesicles. This suggests that both peptides interfere with release by preventing interactions of synapsins with actin. Thus, interactions of domains C and E with the actin cytoskeleton may allow synapsins to perform two roles in regulating release, whereas domain A has an actin-independent function that regulates transmitter release in a phosphorylation-sensitive manner.