Cardiomyopathy Mutations in Metavinculin Disrupt Regulation of Vinculin-Induced F-Actin Assemblies.
Cardiomyopathy Mutations in Metavinculin Disrupt Regulation of Vinculin-Induced F-Actin Assemblies.
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Metavinculin 的心肌病突变破坏了 Vinculin 诱导的 F-肌动蛋白组装的调节。
DOI：
10.1016/j.jmb.2019.02.024
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发表时间：
2019
影响因子：
5.6
通讯作者：
Campbell,SharonL
中科院分区：
文献类型：
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作者：
Sarker,Muzaddid;Lee,HyunnaT;Mei,Lin;Krokhotin,Andrey;deLosReyes,SantiagoEspinosa;Yen,Laura;Costantini,LindseyM;Griffith,Jack;Dokholyan,NikolayV;Alushin,GregoryM;Campbell,SharonL
衰弱性心脏病，特别是扩张性和肥厚性心肌病（CM），与后黏着斑蛋白（一种更大的必需细胞骨架蛋白黏着斑蛋白亚型）的点突变有关。后黏着斑蛋白与黏着斑蛋白在心脏组织中以亚化学计量比共表达。后黏着斑蛋白尾部结构域（MVt）中的CM突变发生在将其与黏着斑蛋白尾部结构域（Vt）区分开的额外68个残基插入物内。Vt结合肌动蛋白丝（F-actin）并促进黏着斑蛋白二聚化以将F-actin捆绑成厚纤维。虽然MVt以与Vt类似的方式结合到F-肌动蛋白，但MVt不能形成F-肌动蛋白集束并抑制Vt介导的F-肌动蛋白集束。我们进行了F-肌动蛋白共沉降和负染EM实验，以剖析协调作用的后黏着斑蛋白和黏着斑蛋白在肌动蛋白纤维组装和三个已知的后黏着斑蛋白CM突变的影响。这些CM突变体被发现弱诱导无序的F-肌动蛋白组件的形成。值得注意的是，它们不能抑制Vt介导的F-肌动蛋白成束，而是促进嵌入线性束的大组件的形成。MVt结合F-肌动蛋白的计算模型表明，MVt经历了构象变化，许可形成一个突出的子域纳入插入，这在空间上防止二聚化和捆绑的F-肌动蛋白的Vt。亚结构域的形成是不稳定的CM突变，破坏这种抑制机制。这些研究结果提供了新的机制的见解，元黏着斑蛋白的能力，调整肌动蛋白的组织黏着斑蛋白，并表明，这一过程的失调CM突变体可能是其故障的疾病。
Debilitating heart conditions, notably dilated and hypertrophic cardiomyopathies (CMs), are associated with point mutations in metavinculin, a larger isoform of the essential cytoskeletal protein vinculin. Metavinculin is co-expressed with vinculin at sub-stoichiometric ratios in cardiac tissues. CM mutations in the metavinculin tail domain (MVt) occur within the extra 68-residue insert that differentiates it from the vinculin tail domain (Vt). Vt binds actin filaments (F-actin) and promotes vinculin dimerization to bundle F-actin into thick fibers. While MVt binds to F-actin in a similar manner to Vt, MVt is incapable of F-actin bundling and inhibits Vt-mediated F-actin bundling. We performed F-actin co-sedimentation and negative-stain EM experiments to dissect the coordinated roles of metavinculin and vinculin in actin fiber assembly and the effects of three known metavinculin CM mutations. These CM mutants were found to weakly induce the formation of disordered F-actin assemblies. Notably, they fail to inhibit Vt-mediated F-actin bundling and instead promote formation of large assemblies embedded with linear bundles. Computational models of MVt bound to F-actin suggest that MVt undergoes a conformational change licensing the formation of a protruding sub-domain incorporating the insert, which sterically prevents dimerization and bundling of F-actin by Vt. Sub-domain formation is destabilized by CM mutations, disrupting this inhibitory mechanism. These findings provide new mechanistic insights into the ability of metavinculin to tune actin organization by vinculin and suggest that dysregulation of this process by CM mutants could underlie their malfunction in disease.