NAD plus improves neuromuscular development in a zebrafish model of FKRP-associated dystroglycanopathy
NAD plus improves neuromuscular development in a zebrafish model of FKRP-associated dystroglycanopathy
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DOI：
10.1186/s13395-019-0206-1
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发表时间：
2019-08-07
期刊：
影响因子：
4.9
通讯作者：
Henry, Clarissa A.
中科院分区：
文献类型：
--
作者：
Bailey, Erin C.;Alrowaished, Sarah S.;Henry, Clarissa A.
继发性肌营养不良是由参与肌营养不良糖基化的基因突变引起的肌营养不良。肌营养不良聚糖的糖基化对于肌纤维粘附于肌肉细胞外基质（肌基质）是必不可少的。虽然在一些继发性肌营养不良蛋白聚糖病中，肌基质被破坏，但尚不清楚改善肌基质是否对这些疾病有益。我们以前确定，无论是NAD+补充或桩蛋白的过表达是足以改善肌肉结构和原发性肌营养不良聚糖病的斑马鱼模型中的肌基质。在这里，我们研究这些调制如何影响神经肌肉表型在斑马鱼fukutin相关蛋白（fkrp）morphants模型FKRP相关的继发性肌营养不良。结果我们发现，在肌肉发育之前补充NAD+改善了fkrp变体的肌肉结构、肌腱连接结构和肌肉功能。然而，桩蛋白过表达并没有改善fkrp变体中的任何这些参数。由于运动也需要神经肌肉接头的形成，我们研究了早期神经肌肉接头的发展fkrp变形。神经肌肉接头的长度在fkrp变体中被破坏。在神经肌肉接头发育之前补充NAD+改善了长度。我们研究了肌营养不良蛋白聚糖（dag1）morphants中NMJ的形成，发现尽管dag1 morphants中NMJ的形态被破坏，但NAD+不足以改善dag1 morphants中NMJ的形态。Fkrp的普遍过表达挽救了fkrp变形体表型，但肌肉特异性过表达仅改善了肌腱连接结构。结论Fkrp在骨骼肌、肌腱接头和神经肌肉接头的发育中起着重要的作用。这些数据还表明，至少在斑马鱼模型中，FKRP相关的肌营养不良聚糖病并不完全表型DG缺陷。桩蛋白过表达改善dag1变体的肌肉结构，但不改善fkrp变体。相比之下，NAD+补充改善了fkrp morphants的NMJ形态，但没有dag1 morphants。最后，这些数据表明Fkrp的肌肉特异性表达不足以拯救肌肉发育和稳态。
Background Secondary dystroglycanopathies are muscular dystrophies that result from mutations in genes that participate in Dystroglycan glycosylation. Glycosylation of Dystroglycan is essential for muscle fibers to adhere to the muscle extracellular matrix (myomatrix). Although the myomatrix is disrupted in a number of secondary dystroglycanopathies, it is unknown whether improving the myomatrix is beneficial for these conditions. We previously determined that either NAD+ supplementation or overexpression of Paxillin are sufficient to improve muscle structure and the myomatrix in a zebrafish model of primary dystroglycanopathy. Here, we investigate how these modulations affect neuromuscular phenotypes in zebrafish fukutin-related protein (fkrp) morphants modeling FKRP-associated secondary dystroglycanopathy. Results We found that NAD+ supplementation prior to muscle development improved muscle structure, myotendinous junction structure, and muscle function in fkrp morphants. However, Paxillin overexpression did not improve any of these parameters in fkrp morphants. As movement also requires neuromuscular junction formation, we examined early neuromuscular junction development in fkrp morphants. The length of neuromuscular junctions was disrupted in fkrp morphants. NAD+ supplementation prior to neuromuscular junction development improved length. We investigated NMJ formation in dystroglycan (dag1) morphants and found that although NMJ morphology is disrupted in dag1 morphants, NAD+ is not sufficient to improve NMJ morphology in dag1 morphants. Ubiquitous overexpression of Fkrp rescued the fkrp morphant phenotype but muscle-specific overexpression only improved myotendinous junction structure. Conclusions These data indicate that Fkrp plays an early and essential role in muscle, myotendinous junction, and neuromuscular junction development. These data also indicate that, at least in the zebrafish model, FKRP-associated dystroglycanopathy does not exactly phenocopy DG-deficiency. Paxillin overexpression improves muscle structure in dag1 morphants but not fkrp morphants. In contrast, NAD+ supplementation improves NMJ morphology in fkrp morphants but not dag1 morphants. Finally, these data show that muscle-specific expression of Fkrp is insufficient to rescue muscle development and homeostasis.