PDF(Pubmed)
Abstract：
Nemaline myopathy (NM) is one of the most common non-dystrophic genetic muscle disorders. NM is often associated with mutations in the NEB gene. Even though the exact NEB-NM pathophysiological mechanisms remain unclear, histological analyses of patients\' muscle biopsies often reveal unexplained accumulation of glycogen and abnormally shaped mitochondria. Hence, the aim of the present study was to define the exact molecular and cellular cascade of events that would lead to potential changes in muscle energetics in NEB-NM. For that, we applied a wide range of biophysical and cell biology assays on skeletal muscle fibres from NM patients as well as untargeted proteomics analyses on isolated myofibres from a muscle-specific nebulin-deficient mouse model. Unexpectedly, we found that the myosin stabilizing conformational state, known as super-relaxed state, was significantly impaired, inducing an increase in the energy (ATP) consumption of resting muscle fibres from NEB-NM patients when compared with controls or with other forms of genetic/rare, acquired NM. This destabilization of the myosin super-relaxed state had dynamic consequences as we observed a remodeling of the metabolic proteome in muscle fibres from nebulin-deficient mice. Altogether, our findings explain some of the hitherto obscure hallmarks of NM, including the appearance of abnormal energy proteins and suggest potential beneficial effects of drugs targeting myosin activity/conformations for NEB-NM.
摘要：
神经肌病（NM）是最常见的非营养不良性遗传性肌肉疾病之一。NM通常与NEB基因突变有关。尽管NEB-NM的确切病理生理机制尚不清楚，患者肌肉活检的组织学分析通常显示原因不明的糖原积累和异常形状的线粒体。因此，本研究的目的是确定导致NEB-NM中肌肉能量学潜在变化的事件的确切分子和细胞级联。为此，我们对NM患者的骨骼肌纤维进行了广泛的生物物理和细胞生物学分析,并对来自肌肉特异性星云缺陷小鼠模型的分离肌纤维进行了非靶向蛋白质组学分析.出乎意料的是,我们发现肌球蛋白稳定的构象状态，被称为超级放松状态，严重受损，与对照组或其他形式的遗传/罕见相比，诱导NEB-NM患者静息肌纤维的能量（ATP）消耗增加，收购NM。肌球蛋白超松弛状态的这种不稳定具有动态后果，因为我们观察到来自星云缺乏小鼠的肌肉纤维中代谢蛋白质组的重塑。总之,我们的发现解释了迄今为止NM的一些模糊标志，包括异常能量蛋白的出现，并提示针对NEB-NM的肌球蛋白活性/构象的药物的潜在有益作用。
