Altered neurotransmitter release machinery in mice deficient for the deubiquitinating enzyme Usp14
Altered neurotransmitter release machinery in mice deficient for the deubiquitinating enzyme Usp14
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DOI：
10.1152/ajpcell.00326.2010
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发表时间：
2012-02-01
影响因子：
5.5
通讯作者：
Miller, Richard J.
中科院分区：
文献类型：
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作者：
Bhattacharyya, Bula J.;Wilson, Scott M.;Miller, Richard J.
Bhattacharyya BJ，Wilson SM，Jung H，米勒RJ.去泛素化酶Usp 14缺陷小鼠神经递质释放机制的改变Am J Physiol Cell Physiol 302：C698-C708，2012.首次发表于2011年11月9日; doi：10.1152/ajpcell.00326.2010.-纯合子共济失调小鼠（ax（J））表达水平降低的去泛素化酶Usp 14。它们在2-3周龄时出现严重震颤，随后出现后肢瘫痪，并在6-8周龄时死亡。虽然遍在蛋白蛋白酶体系统的变化通常会导致遍在蛋白聚集体的积累和神经元损失，但在ax（J）小鼠中并未观察到这些病理标记物。相反，在ax（J）小鼠的中枢和外周神经系统中都观察到神经传递缺陷。我们现在已经在ax（J）小鼠的外周神经传递中发现了几个新的改变。利用双微电极电压钳技术对axJ小鼠膈肌进行电生理研究，发现在正常神经递质释放条件下，axJ小鼠在高频刺激（HFS）下，缺乏成对脉冲易化，终板电流下降呈频率依赖性增加。结合电生理学和苯乙烯染料染色显示量子含量显着减少，在初始和高原部分的HFS列车。此外，在HFS过程中苯乙烯基染料（FM染料）的摄取表明，易于释放的囊泡池的大小显着减少。苯乙烯基染料的脱色率表明ax（J）神经肌肉接头在强烈活动期间无法动员足够数量的囊泡。这些结果意味着ax（J）神经末梢不能募集足够数量的囊泡以跟上递质释放的生理速率。因此，突触蛋白的泛素化似乎在神经递质释放机制的正常运作和调节突触囊泡池的大小中起重要作用。
Bhattacharyya BJ, Wilson SM, Jung H, Miller RJ. Altered neurotransmitter release machinery in mice deficient for the deubiquitinating enzyme Usp14. Am J Physiol Cell Physiol 302: C698-C708, 2012. First published November 9, 2011; doi:10.1152/ajpcell.00326.2010.-Homozygous ataxic mice (ax(J)) express reduced levels of the deubiquitinating enzyme Usp14. They develop severe tremors by 2-3 wk of age, followed by hindlimb paralysis, and death by 6-8 wk. While changes in the ubiquitin proteasome system often result in the accumulation of ubiquitin protein aggregates and neuronal loss, these pathological markers are not observed in the ax(J) mice. Instead, defects in neurotransmission were observed in both the central and peripheral nervous systems of ax(J) mice. We have now identified several new alterations in peripheral neurotransmission in the ax(J) mice. Using the two-microelectrode voltage clamp technique on diaphragm muscles of axJ mice, we observed that under normal neurotransmitter release conditions axJ mice lacked paired-pulse facilitation and exhibited a frequency-dependent increase in rundown of the end plate current at high-frequency stimulation (HFS). Combined electrophysiology and styryl dye staining revealed a significant reduction in quantal content during the initial and plateau portions of the HFS train. In addition, uptake of styryl dyes (FM dye) during HFS demonstrated that the size of the readily releasable vesicle pool was significantly reduced. Destaining rates for styryl dyes suggested that ax(J) neuromuscular junctions are unable to mobilize a sufficient number of vesicles during times of intense activity. These results imply that ax(J) nerve terminals are unable to recruit a sufficient number of vesicles to keep pace with physiological rates of transmitter release. Therefore, ubiquitination of synaptic proteins appears to play an important role in the normal operation of the neurotransmitter release machinery and in regulating the size of pools of synaptic vesicles.