Selective Neuromuscular Denervation in Taiwanese Severe SMA Mouse Can Be Reversed by Morpholino Antisense Oligonucleotides.
Selective Neuromuscular Denervation in Taiwanese Severe SMA Mouse Can Be Reversed by Morpholino Antisense Oligonucleotides.
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DOI：
10.1371/journal.pone.0154723
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Jong YJ
中科院分区：
文献类型：
--
作者：
Lin TL;Chen TH;Hsu YY;Cheng YH;Juang BT;Jong YJ
脊髓性肌萎缩症（spinal muscular atrophy，SMA）是一种由运动神经元存活蛋白（survival of motor neuron，SMN）缺陷引起的常染色体隐性遗传性运动神经元疾病，其主要表现为突触缺陷和脊髓运动神经元死亡。在SMNΔ7 SMA小鼠模型中，发现神经肌肉接头（NMJ）异常参与SMA发病机制。然而，在另一种常用的小鼠模型（台湾SMA小鼠）中是否存在类似的NMJ病理学结果尚未得到充分研究。为了检查台湾重度SMA小鼠模型（Smn-/-; SMN 2 tg/0）的NMJ，其特征在于严重的表型和出生后第9天（P）之前的死亡，我们研究了P1至P9的25个轴向肌和背侧肌。我们用抗神经丝和抗突触素抗体标记神经末梢，用α-银环蛇毒素标记乙酰胆碱受体（AChR）。我们发现，严重的NMJ去神经支配（<50%完全受神经支配的终板）选择性地发生在P5的趾短屈肌2和3（FDB-2/3）肌肉中，并且完全去神经支配的终板的百分比增加与SMA进展相关。此外，突触素信号不存在于终板相比，控制同窝小鼠，这表明囊泡运输可能只在最后阶段受到影响。随后，我们在P0通过皮下注射给予台湾重度SMA小鼠吗啉代（MO）反义寡核苷酸（80 μg/g）。我们发现MO显著逆转FDB-2/3肌肉中的NMJ去神经支配，并延长台湾重度SMA小鼠的存活时间。我们的结论是，台湾严重SMA小鼠FDB-2/3肌肉的早期NMJ去神经支配可以通过MO治疗逆转。台湾重度SMA小鼠的FDB-2/3肌肉为评估SMA临床前研究中药物治疗的有效性提供了非常敏感的平台。
Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease caused by deficiency of the survival of motor neuron (SMN) protein, which leads to synaptic defects and spinal motor neuron death. Neuromuscular junction (NMJ) abnormalities have been found to be involved in SMA pathogenesis in the SMNΔ7 SMA mouse model. However, whether similar NMJ pathological findings present in another commonly used mouse model, the Taiwanese SMA mouse, has not been fully investigated. To examine the NMJs of the Taiwanese severe SMA mouse model (Smn-/-; SMN2tg/0), which is characterized by severe phenotype and death before postnatal day (P) 9, we investigated 25 axial and appendicular muscles from P1 to P9. We labelled the muscles with anti-neurofilament and anti-synaptophysin antibodies for nerve terminals and α-bungarotoxin for acetylcholine receptors (AChRs). We found that severe NMJ denervation (<50% fully innervated endplates) selectively occurred in the flexor digitorum brevis 2 and 3 (FDB-2/3) muscles from P5, and an increased percentage of fully denervated endplates correlated with SMA progression. Furthermore, synaptophysin signals were absent at the endplate compared to control littermate mice, suggesting that vesicle transport might only be affected at the end stage. Subsequently, we treated the Taiwanese severe SMA mice with morpholino (MO) antisense oligonucleotides (80 μg/g) via subcutaneous injection at P0. We found that MO significantly reversed the NMJ denervation in FDB-2/3 muscles and extended the survival of Taiwanese severe SMA mice. We conclude that early NMJ denervation in the FDB-2/3 muscles of Taiwanese severe SMA mice can be reversed by MO treatment. The FDB-2/3 muscles of Taiwanese severe SMA mice provide a very sensitive platform for assessing the effectiveness of drug treatments in SMA preclinical studies.