The zebrafish dag1 mutant: a novel genetic model for dystroglycanopathies
The zebrafish dag1 mutant: a novel genetic model for dystroglycanopathies
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DOI：
10.1093/hmg/ddr047
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发表时间：
2011-05-01
影响因子：
3.5
通讯作者：
Beggs, Alan H.
中科院分区：
文献类型：
--
作者：
Gupta, Vandana;Kawahara, Genri;Beggs, Alan H.
在一个正向遗传学方法，以确定新的基因的先天性肌肉疾病，斑马鱼突变，指定patchytail，被确定为表现出退化的肌肉纤维与受损的运动行为。遗传作图确定了一个基因组位点，含有斑马鱼的直向同源的肌营养不良蛋白聚糖基因（DAG 1）。斑尾鱼在dag 1中含有点突变（c.1700T > A），导致错义改变p.V567D。这种变化与转录物减少和蛋白质完全缺失有关。α-肌营养不良蛋白聚糖和β-肌营养不良蛋白聚糖的缺乏引起肌营养不良蛋白聚糖复合物的不稳定，导致膜损伤。膜损伤位于肌间隔处的细胞外基质以及相邻肌纤维之间的基底膜上。这些研究还确定了肌营养不良蛋白聚糖缺陷肌肉在受精后3天（dpf）的三联体结构异常，显著先于在7 dpf变得明显的肌膜损伤。免疫荧光研究确定了一个亚群的肌营养不良蛋白聚糖，表达在正常骨骼肌的t-小管。在dag 1基因突变的鱼，较小和不规则形状的t-小管囊泡，以及高度紊乱的终端肌浆网池，是常见的。除了骨骼肌缺陷外，dag 1基因突变的鱼还具有大脑异常和后房和前房的眼部缺陷。肌营养不良蛋白聚糖缺陷鱼的这些表型高度地使人联想到在人类条件肌肉-眼-脑疾病和沃克-沃伯格综合征中观察到的表型。这种动物模型将提供独特的机会，在广泛的肌营养不良蛋白聚糖病的生物学功能的理解，这种基因在高等脊椎动物的破坏导致早期胚胎致死。
In a forward genetic approach to identify novel genes for congenital muscle diseases, a zebrafish mutant, designated patchytail, was identified that exhibits degenerating muscle fibers with impaired motility behavior. Genetic mapping identified a genomic locus containing the zebrafish ortholog of the dystroglycan gene (DAG1). Patchytail fish contain a point mutation (c.1700T > A) in dag1, resulting in a missense change p.V567D. This change is associated with reduced transcripts and a complete absence of protein. The absence of alpha-dystroglycan and beta-dystroglycan caused destabilization of dystroglycan complex, resulting in membrane damages. Membrane damage was localized on the extracellular matrix at myosepta as well as basement membrane between adjacent myofibers. These studies also identified structural abnormalities in triads at 3 days post fertilization (dpf) of dystroglycan-deficient muscles, significantly preceding sarcolemmal damage that becomes evident at 7 dpf. Immunofluorescence studies identified a subpopulation of dystroglycan that is expressed at t-tubules in normal skeletal muscles. In dag1-mutated fish, smaller and irregular-shaped t-tubule vesicles, as well as highly disorganized terminal cisternae of sarcoplasmic reticulum, were common. In addition to skeletal muscle defects, dag1-mutated fish have brain abnormalities and ocular defects in posterior as well as anterior chambers. These phenotypes of dystroglycan-deficient fish are highly reminiscent of the phenotypes observed in the human conditions muscle-eye-brain disease and Walker-Warburg syndrome. This animal model will provide unique opportunities in the understanding of biological functions of dystroglycan in a wide range of dystroglycanopathies, as disruption of this gene in higher vertebrates results in early embryonic lethality.