University Paris Diderot-Paris 7/CNRS EAC4413, Unit of Functional and Adaptive Biology, Laboratory of Stress and Pathologies of the Cytoskeleton, F-75013, Paris, France.
Exp Cell Res. 2011 Apr 1;317(6):886-97. doi: 10.1016/j.yexcr.2011.01.013. Epub 2011 Jan 22.
Disorganization of the desmin network is associated with cardiac and skeletal myopathies characterized by accumulation of desmin-containing aggregates in the cells. Multiple associations of intermediate filament proteins form a network to increase mechanical and functional stability. Synemin is a desmin-associated type VI intermediate filament protein. Neither its impact on desmin network nor how it integrates into desmin filament is yet elucidated. To gain more insight into the molecular basis of these processes, we coexpressed synemin with different desmin mutants in ex vivo models. The screening of fourteen desmin mutants showed that synemin with desmin mutants revealed two behaviors. Firstly, synemin was co-localized in desmin aggregates and its coexpression decreased the number of cells containing aggregates. Secondly, synemin was excluded from the aggregates, then synemin had no effect on desmin network organization. Among fourteen desmin mutants, there were only three mutants, p.E401K, p.R406W and p.E413K, in which synemin was not found in aggregates. This behavior was correlated to the abnormal salt-bridges of desmin-dimer as seen in silico constructs. Moreover, desmin constructs in silico and published results in literature have predicted that the salt-bridges absence in the desmin filament building prevent longitudinal annealing and/or radial compaction. These results suggest that the state of desmin-filament assembly is crucial for synemin anchorage and consequently might involve mechanical and functional stability of the cytoskeletal network.
中间丝蛋白的多种相互作用形成网络，以增加机械和功能稳定性。连接蛋白是一种与结蛋白相关的 VI 型中间丝蛋白。它对结蛋白网络的影响及其如何整合到结蛋白丝中尚不清楚。为了更深入地了解这些过程的分子基础，我们在体外模型中与不同的结蛋白突变体共同表达了连接蛋白。对 14 种结蛋白突变体的筛选表明，连接蛋白与结蛋白突变体共同表达时表现出两种行为。首先，连接蛋白在结蛋白聚集体中共定位，其共表达减少了含有聚集体的细胞数量。其次，连接蛋白被排斥在聚集体之外，然后连接蛋白对结蛋白网络组织没有影响。在 14 种结蛋白突变体中，只有 p.E401K、p.R406W 和 p.E413K 这三种突变体中的连接蛋白未在聚集体中发现。这种行为与计算机结构中观察到的结蛋白二聚体异常盐桥有关。此外，计算机结构中的结蛋白结构和文献中发表的结果预测，结蛋白丝构建中盐桥的缺失阻止了纵向退火和/或径向压缩。这些结果表明，结蛋白丝组装的状态对接连蛋白的锚定至关重要，因此可能涉及细胞骨架网络的机械和功能稳定性。
