The Vesicular Acetylcholine Transporter Is Required for Neuromuscular Development and Function
The Vesicular Acetylcholine Transporter Is Required for Neuromuscular Development and Function
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DOI：
10.1128/mcb.00245-09
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发表时间：
2009-10-01
影响因子：
5.3
通讯作者：
Prado, Vania F.
中科院分区：
文献类型：
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作者：
de Castro, Braulio M.;De Jaeger, Xavier;Prado, Vania F.
囊泡型乙酰胆碱转运体(Vacht)通过突触小泡介导ACh的储存。然而，独立于游艇的ACH版本被认为在开发过程中非常重要。在这里，我们产生了Vacht基因敲除小鼠，并测试了Vacht非依赖性ACh释放的生理学相关性。纯合子Vacht基因敲除小鼠出生后不久死亡，表明Vacht介导的ACh储存是生命所必需的。事实上，从纯合基因敲除的大脑中获得的突触体不能在去极化时释放ACh。令人惊讶的是，骨骼-神经肌肉交界处的电生理记录显示，Vacht基因敲除小鼠出现了幅度和频率降低的自发微型终板电位，这可能是ACh被动运输到突触小泡的结果。有趣的是，Vacht基因敲除后，胆碱乙酰转移酶、高亲和力胆碱转运体和ACh的数量显著增加。然而，这些小鼠的神经肌肉接头的发育受到严重影响。突变的Vacht小鼠的运动神经元和神经末梢数量增加。终板较大，神经异常发芽，肌肉坏死。这些异常类似于由于缺乏胆碱乙酰转移酶而无法合成ACh的小鼠。我们的结果表明，Vacht对运动神经元的正常发育和ACh的释放是必不可少的。
The vesicular acetylcholine (ACh) transporter (VAChT) mediates ACh storage by synaptic vesicles. However, the VAChT-independent release of ACh is believed to be important during development. Here we generated VAChT knockout mice and tested the physiological relevance of the VAChT-independent release of ACh. Homozygous VAChT knockout mice died shortly after birth, indicating that VAChT-mediated storage of ACh is essential for life. Indeed, synaptosomes obtained from brains of homozygous knockouts were incapable of releasing ACh in response to depolarization. Surprisingly, electrophysiological recordings at the skeletal-neuromuscular junction show that VAChT knockout mice present spontaneous miniature end-plate potentials with reduced amplitude and frequency, which are likely the result of a passive transport of ACh into synaptic vesicles. Interestingly, VAChT knockouts exhibit substantial increases in amounts of choline acetyltransferase, high-affinity choline transporter, and ACh. However, the development of the neuromuscular junction in these mice is severely affected. Mutant VAChT mice show increases in motoneuron and nerve terminal numbers. End plates are large, nerves exhibit abnormal sprouting, and muscle is necrotic. The abnormalities are similar to those of mice that cannot synthesize ACh due to a lack of choline acetyltransferase. Our results indicate that VAChT is essential to the normal development of motor neurons and the release of ACh.