Disease severity and thin filament regulation in M9R TPM3 nemaline myopathy
Disease severity and thin filament regulation in M9R TPM3 nemaline myopathy
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DOI：
10.1097/nen.0b013e318183a44f
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发表时间：
2008-09-01
影响因子：
3.2
通讯作者：
Cooper, Sandra T.
中科院分区：
文献类型：
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作者：
Ilkovski, Biljana;Mokbel, Nancy;Cooper, Sandra T.
在一个TPM 3（α-原肌球蛋白（慢））M9 R突变的澳大利亚家族中研究了肌无力的机制。对来自2名患者的5份肌肉样本的详细蛋白质分析表明，线虫体仅限于表达TPM 3基因的萎缩的1型（慢）纤维。发育表达研究表明，α-原肌球蛋白（慢），直到出生后才以显着水平表达，从而可能解释了儿童（而不是先天性）疾病发作的TPM 3线状体肌病。等电聚焦表明，α-原肌球蛋白（慢）二聚体，野生型和M9 R-α-原肌球蛋白（慢）的比例相等，是主要的原肌球蛋白物种在3个独立的肌肉群从受影响的病人。这些研究结果表明，肌病相关的慢纤维优势可能有助于在TPM 3线状体肌病，因为表达突变蛋白的纤维的比例增加的弱点的严重程度。使用重组蛋白和远Western印迹，我们证明了与β-原肌球蛋白相比，原调节蛋白对α-原肌球蛋白（慢）的亲和力更高; α-原肌球蛋白（慢）内的M9 R取代大大降低了这种相互作用。最后，将M9 R突变和野生型α-原肌球蛋白（慢）转染到成肌细胞中，发现突变蛋白减少了对应力纤维的掺入和对丝状肌动蛋白网络的破坏。总的来说，这些结果提供了对M9 R-TPM 3线状体肌病的临床特征和发病机制的见解。
The mechanism of muscle weakness was investigated in an Australian family with an M9R Mutation in TPM3 (alpha-tropomyosin(slow)). Detailed protein analyses of 5 muscle samples from 2 patients showed that nemaline bodies are restricted to atrophied Type 1 (slow) fibers in which the TPM3 gene is expressed. Developmental expression studies showed that alpha-tropomyosin(slow), is not expressed at significant levels until after birth, thereby likely explaining the childhood (rather than congenital) disease onset in TPM3 nemaline myopathy. Isoelectric focusing demonstrated that alpha-tropomyosin(slow) dimers, composed of equal ratios of wild-type and M9R-alpha-tropomyosin(slow), are the dominant tropomyosin species in 3 separate muscle groups from an affected patient. These findings suggest that myopathy-related slow fiber predominance likely contributes to the severity of weakness in TPM3 nemaline myopathy because of increased proportions of fibers that express the mutant protein. Using recombinant proteins and far Western blot, we demonstrated a higher affinity of tropomodulin for alpha-tropomyosin(slow) compared with beta-tropomyosin; the M9R substitution within alpha-tropomyosin(slow) greatly reduced this interaction. Finally, transfection of the M9R mutated and wild-type alpha-tropomyosin(slow), into myoblasts revealed reduced incorporation into stress fibers and disruption of the filamentous actin network by the mutant protein. Collectively, these results provide insights into the clinical features and pathogenesis of M9R-TPM3 nemaline myopathy.