Early signs of architectural and biomechanical failure in isolated myofibers and immortalized myoblasts from desmin-mutant knock-in mice.
Early signs of architectural and biomechanical failure in isolated myofibers and immortalized myoblasts from desmin-mutant knock-in mice.
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DOI：
10.1038/s41598-017-01485-x
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发表时间：
2017-05-03
影响因子：
4.6
通讯作者：
Friedrich O
中科院分区：
文献类型：
--
作者：
Diermeier S;Iberl J;Vetter K;Haug M;Pollmann C;Reischl B;Buttgereit A;Schürmann S;Spörrer M;Goldmann WH;Fabry B;Elhamine F;Stehle R;Pfitzer G;Winter L;Clemen CS;Herrmann H;Schröder R;Friedrich O
在横纹肌中，结蛋白中间丝将收缩性肌原纤维器与线粒体、细胞核和肌膜连接起来。结蛋白网络在肌细胞中的关键作用是显而易见的，因为人类结蛋白基因的突变导致严重的肌病和心肌病。在这里，我们研究了骨骼肌病理分离的肌纤维和肌原纤维从年轻的杂合和纯合R349P结蛋白基因敲入小鼠，携带最常见的人类结蛋白错义突变R350P的直系同源。我们证明，突变结蛋白改变肌原纤维的细胞结构，显着破坏侧肌节晶格和扭曲肌原纤维角轴向取向。生物力学评估显示，R349P小鼠的纤维束中存在拉伸诱导损伤的高倾向性。值得注意的是，Ca2 +敏感性和被动肌原纤维张力降低杂合纤维束，但增加纯合纤维束相比，野生型小鼠。在一个平行的方法中，我们产生并随后进行永生化的杂合R349P结蛋白敲入成肌细胞的磁镊子实验，揭示了显着增加肌膜的侧向刚度。我们的数据表明，突变结蛋白已经显着阻碍肌纤维肌病的症状前阶段的肌细胞结构和功能。
In striated muscle, desmin intermediate filaments interlink the contractile myofibrillar apparatus with mitochondria, nuclei, and the sarcolemma. The desmin network’s pivotal role in myocytes is evident since mutations in the human desmin gene cause severe myopathies and cardiomyopathies. Here, we investigated skeletal muscle pathology in myofibers and myofibrils isolated from young hetero- and homozygous R349P desmin knock-in mice, which carry the orthologue of the most frequent human desmin missense mutation R350P. We demonstrate that mutant desmin alters myofibrillar cytoarchitecture, markedly disrupts the lateral sarcomere lattice and distorts myofibrillar angular axial orientation. Biomechanical assessment revealed a high predisposition to stretch-induced damage in fiber bundles of R349P mice. Notably, Ca2 +-sensitivity and passive myofibrillar tension were decreased in heterozygous fiber bundles, but increased in homozygous fiber bundles compared to wildtype mice. In a parallel approach, we generated and subsequently subjected immortalized heterozygous R349P desmin knock-in myoblasts to magnetic tweezer experiments that revealed a significantly increased sarcolemmal lateral stiffness. Our data suggest that mutated desmin already markedly impedes myocyte structure and function at pre-symptomatic stages of myofibrillar myopathies.