Bühler Anja, Kustermann Monika, Bummer Tiziana, Rottbauer Wolfgang, Sandri Marco, Just Steffen
Molecular Cardiology, University of Ulm, 89081 Ulm, Germany.
Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany.
Int J Mol Sci. 2016 Jan 30;17(2):187. doi: 10.3390/ijms17020187.
Orchestrated protein synthesis and degradation is fundamental for proper cell function. In muscle, impairment of proteostasis often leads to severe cellular defects finally interfering with contractile function. Here, we analyze for the first time the role of Atrogin-1, a muscle-specific E3 ubiquitin ligase known to be involved in the regulation of protein degradation via the ubiquitin proteasome and the autophagy/lysosome systems, in the in vivo model system zebrafish (Danio rerio). We found that targeted inactivation of zebrafish Atrogin-1 leads to progressive impairment of heart and skeletal muscle function and disruption of muscle structure without affecting early cardiogenesis and skeletal muscle development. Autophagy is severely impaired in Atrogin-1-deficient zebrafish embryos resulting in the disturbance of the cytoarchitecture of cardiomyocytes and skeletal muscle cells. These observations are consistent with molecular and ultrastructural findings in an Atrogin-1 knockout mouse and demonstrate that the zebrafish is a suitable vertebrate model to study the molecular mechanisms of Atrogin-1-mediated autophagic muscle pathologies and to screen for novel therapeutically active substances in high-throughput in vivo small compound screens (SCS).
精心编排的蛋白质合成与降解对于细胞的正常功能至关重要。在肌肉中，蛋白质稳态的受损常常导致严重的细胞缺陷，最终干扰收缩功能。在此，我们首次在体内模型系统斑马鱼（Danio rerio）中分析了Atrogin-1的作用，Atrogin-1是一种肌肉特异性E3泛素连接酶，已知其通过泛素蛋白酶体和自噬/溶酶体系统参与蛋白质降解的调控。我们发现，斑马鱼Atrogin-1的靶向失活会导致心脏和骨骼肌功能的渐进性损害以及肌肉结构的破坏，而不影响早期心脏发生和骨骼肌发育。Atrogin-1缺陷型斑马鱼胚胎中的自噬严重受损，导致心肌细胞和骨骼肌细胞的细胞结构紊乱。这些观察结果与Atrogin-1基因敲除小鼠的分子和超微结构研究结果一致，并表明斑马鱼是研究Atrogin-1介导的自噬性肌肉病变分子机制以及在高通量体内小分子化合物筛选（SCS）中筛选新型治疗活性物质的合适脊椎动物模型。
