Severe muscle disease-causing desmin mutations interfere with in vitro filament assembly at distinct stages
Severe muscle disease-causing desmin mutations interfere with in vitro filament assembly at distinct stages
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DOI：
10.1073/pnas.0504568102
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发表时间：
2005-10-18
影响因子：
11.1
通讯作者：
Herrmann, H
中科院分区：
文献类型：
--
作者：
Bär, H;Mücke, N;Herrmann, H
结蛋白是肌肉的主要中间丝 (IF) 蛋白。最近，据报道结蛋白基因突变可引起家族性或散发性人类骨骼疾病，以及心脏、肌病，称为结蛋白相关性肌病（DRM）。尽管所有这些突变都会导致相同的组织病理学缺陷，即结蛋白聚集，但目前尚不清楚这些突变对肌细胞丝组装和整合到肌细胞细胞骨架网络中的影响。为了更深入地了解这一过程的分子基础，我们研究了结蛋白α螺旋杆结构域内的突变如何影响体外重组蛋白的组装以及cDNA转染细胞中的丝形成能力。虽然 14 个突变体中有 6 个在试管中组装成看似正常的 IF，但其他突变体在不同阶段干扰组装过程，即四聚体形成、单位长度丝 (ULF) 形成、丝伸长和 IF 成熟。相应地，具有体外组装缺陷的突变体在转染细胞中产生点状聚集体，而形成IF的突变体在细胞环境中构成看似正常的IF细胞骨架。目前，完全不清楚为什么后者的突变蛋白也会导致肌细胞中聚集体的形成。因此，这些发现可能是剖析各个子域对结蛋白病理学的贡献的起点，并最终开发治疗干预措施。
Desmin is the major intermediate filament (IF) protein of muscle. Recently, mutations of the desmin gene have been reported to cause familial or sporadic forms of human skeletal, as well as cardiac, myopathy, termed desmin-related myopathy (DRM). The impact of any of these mutations on filament assembly and integration into the cytoskeletal network of myocytes is currently not understood, despite the fact that all cause the same histopathological defect, i.e., desmin aggregation. To gain more insight into the molecular basis of this process, we investigated how mutations within the alpha-helical rod domain of desmin affect both the assembly of the recombinant protein in vitro as well as the filament-forming capacity in cDNA-transfected cells. Whereas 6 of 14 mutants assemble into seemingly normal IFs in the test tube,the other mutants interfere with the assembly process at distinct stages, i.e., tetramer formation, unit-length filament (ULF) formation, filament elongation, and IF maturation. Correspondingly, the mutants with in vitro assembly defects yield dot-like aggregates in transfected cells, whereas the mutants that form IFs constitute a seemingly normal IF cytoskeleton in the cellular context. At present, it is entirely unclear why the latter mutant proteins also lead to aggregate formation in myocytes. Hence, these findings may be a starting point to dissect the contribution of the individual subdomains for desmin pathology and, eventually, the development of therapeutic interventions.