VAChT overexpression increases acetylcholine at the synaptic cleft and accelerates aging of neuromuscular junctions.
VAChT overexpression increases acetylcholine at the synaptic cleft and accelerates aging of neuromuscular junctions.
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DOI：
10.1186/s13395-016-0105-7
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发表时间：
2016
期刊：
影响因子：
4.9
通讯作者：
Valdez G
中科院分区：
文献类型：
--
作者：
Sugita S;Fleming LL;Wood C;Vaughan SK;Gomes MP;Camargo W;Naves LA;Prado VF;Prado MA;Guatimosim C;Valdez G
胆碱能功能障碍发生在衰老过程中和各种疾病中，包括肌萎缩性侧索硬化症（ALS）。然而，它仍然是未知的，是否胆碱能传递的变化有助于年龄和疾病相关的退化的运动系统。在这里，我们研究了适度增加突触乙酰胆碱（ACh）水平对神经肌肉接头（NMJ），肌肉纤维和运动神经元在发育和衰老过程中的作用，并在肌萎缩侧索硬化症（ALS）的小鼠模型。在本研究中使用了含有多拷贝囊泡乙酰胆碱转运蛋白（VAChT）、突变型超氧化物歧化酶1（SOD 1G 93 A）的Chat-ChR 2-EYFP（VAChTHyp）小鼠以及Chat-IRES-Cre和tdTomato转基因小鼠。用光学显微镜检查NMJ、肌纤维和α运动神经元的胞体及其轴突。使用实时定量PCR评估肌肉和脊髓中选择基因的转录本。运动功能测试使用倒置丝网和旋转棒进行。收集电生理记录，以检查肌肉中的微型终板电位（MEPP）。我们表明，VAChT是在脊髓和VAChTHyp小鼠的NMJ升高。我们还表明，MEPPs的幅度是显着较高的VAChTHyp肌肉，表明更多的乙酰胆碱加载到突触囊泡和释放到突触间隙在VAChTHyp小鼠的NMJ相比，对照组小鼠。虽然NMJ的发育在VAChTHyp小鼠中不受影响，但NMJ在成年VAChTHyp小鼠中过早获得了与年龄相关的结构改变。NMJ的这些结构变化伴随着VAChTHyp小鼠的运动缺陷。然而，在VAChTHyp小鼠中，肌纤维的细胞特征和在NMJ和肌纤维中具有关键功能的分子水平在很大程度上没有变化。在ALS的SOD 1G 93 A小鼠模型中，突触ACh的增加加速了NMJ的变性，导致运动缺陷，并导致过早死亡，特别是在雄性小鼠中。本文中的数据表明，突触间隙中ACh水平的增加促进了成年NMJ的退化，导致了与年龄和疾病相关的运动缺陷。因此，我们提出，维持肌肉中正常的胆碱能信号将减缓NMJ的退化，并减轻由衰老和神经肌肉疾病引起的运动功能丧失。
Cholinergic dysfunction occurs during aging and in a variety of diseases, including amyotrophic lateral sclerosis (ALS). However, it remains unknown whether changes in cholinergic transmission contributes to age- and disease-related degeneration of the motor system. Here we investigated the effect of moderately increasing levels of synaptic acetylcholine (ACh) on the neuromuscular junction (NMJ), muscle fibers, and motor neurons during development and aging and in a mouse model for amyotrophic lateral sclerosis (ALS). Chat-ChR2-EYFP (VAChTHyp) mice containing multiple copies of the vesicular acetylcholine transporter (VAChT), mutant superoxide dismutase 1 (SOD1G93A), and Chat-IRES-Cre and tdTomato transgenic mice were used in this study. NMJs, muscle fibers, and α-motor neurons’ somata and their axons were examined using a light microscope. Transcripts for select genes in muscles and spinal cords were assessed using real-time quantitative PCR. Motor function tests were carried out using an inverted wire mesh and a rotarod. Electrophysiological recordings were collected to examine miniature endplate potentials (MEPP) in muscles. We show that VAChT is elevated in the spinal cord and at NMJs of VAChTHyp mice. We also show that the amplitude of MEPPs is significantly higher in VAChTHyp muscles, indicating that more ACh is loaded into synaptic vesicles and released into the synaptic cleft at NMJs of VAChTHyp mice compared to control mice. While the development of NMJs was not affected in VAChTHyp mice, NMJs prematurely acquired age-related structural alterations in adult VAChTHyp mice. These structural changes at NMJs were accompanied by motor deficits in VAChTHyp mice. However, cellular features of muscle fibers and levels of molecules with critical functions at the NMJ and in muscle fibers were largely unchanged in VAChTHyp mice. In the SOD1G93A mouse model for ALS, increasing synaptic ACh accelerated degeneration of NMJs caused motor deficits and resulted in premature death specifically in male mice. The data presented in this manuscript demonstrate that increasing levels of ACh at the synaptic cleft promote degeneration of adult NMJs, contributing to age- and disease-related motor deficits. We thus propose that maintaining normal cholinergic signaling in muscles will slow degeneration of NMJs and attenuate loss of motor function caused by aging and neuromuscular diseases.
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影响因子：
3.3
作者：
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