Nesprin-1 and actin contribute to nuclear and cytoskeletal defects in lamin A/C-deficient cardiomyopathy
Nesprin-1 and actin contribute to nuclear and cytoskeletal defects in lamin A/C-deficient cardiomyopathy
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DOI：
10.1016/j.yjmcc.2010.12.001
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发表时间：
2011-03-01
影响因子：
5
通讯作者：
Fatkin, Diane
中科院分区：
文献类型：
--
作者：
Nikolova-Krstevski, Vesna;Leimena, Christiana;Fatkin, Diane
纤层蛋白A/C突变是家族性扩张型心肌病（DCM）最常见的病因，但其发病机制尚不完全清楚。Nesprins是含有谱蛋白重复序列的蛋白质，可与层粘连蛋白A/C相互作用，是连接核膜和肌动蛋白细胞骨架的核骨架-细胞骨架连接物（LINC）复合物的组成部分。我们的目的是确定nesprin1和actin的变化是否可能导致纯合子Lmna敲除（Lmna(-/-)）小鼠的DCM。在这里，我们发现Lmna（-/-）心肌细胞改变了核膜形态，nesprin1的紊乱以及核和细胞骨架肌动蛋白分布的异质性。免疫沉淀和Western blotting显示了nesprin1与细胞核g -肌动蛋白以及与细胞骨架-肌动蛋白、α -心脏肌动蛋白和α -平滑肌肌动蛋白（α - sma）亚型的功能相互作用。4-6周龄时，Lmna（-/-）小鼠γ -肌动蛋白和α -心肌肌动蛋白水平正常，但α - sma表达增加50%。与a- sma在WT心室切片中的主要血管分布相反，α - sma在Lmna（-/-）切片中呈弥漫性染色模式。渗透性肿胀研究显示，Lmna（-/-）心肌细胞径向肿胀增强，表明细胞骨架不稳定。加入α - sma特异性融合肽可降低渗透应激下的Lmna（-/-）心肌细胞的扩张性。我们的研究结果支持了一个模型，即细胞核和细胞骨架的解耦与LINC复合物的破坏相关，促进了心肌细胞的机械不稳定性和力传递缺陷。核肌动蛋白和细胞骨架肌动蛋白的分布和表达模式的变化表明，多种转录和结构缺陷也可能导致Lmna（-/-）小鼠的DCM。(C) 2010 Elsevier Ltd.版权所有。
Lamin A/C mutations are the most common cause of familial dilated cardiomyopathy (DCM) but the pathogenetic mechanisms are incompletely understood. Nesprins are spectrin repeat-containing proteins that interact with lamin A/C and are components of the linker-of-nucleoskeleton-and-cytoskeleton (LINC) complex that connects the nuclear envelope to the actin cytoskeleton. Our aim was to determine whether changes in nesprin-1 and actin might contribute to DCM in homozygous Lmna knockout (Lmna(-/-)) mice. Here we find that Lmna(-/-) cardiomyocytes have altered nuclear envelope morphology, disorganization of nesprin-1 and heterogeneity in the distribution of nuclear and cytoskeletal actin. Functional interactions of nesprin-1 with nuclear G-actin and with the cytoskeletal gamma-actin, alpha-cardiac actin and alpha-smooth muscle actin (alpha-SMA) isoforms were shown by immunoprecipitation and Western blotting. At 4-6 weeks of age, Lmna(-/-) mice had normal levels of gamma-actin and alpha-cardiac actin, but alpha-SMA expression was increased by 50%. In contrast to the predominant vascular distribution of a-SMA in WT ventricular sections, alpha-SMA had a diffuse staining pattern in Lmna(-/-) sections. Osmotic swelling studies showed enhanced radial swelling in Lmna(-/-) cardiomyocytes indicative of cytoskeletal instability. The distensibility of Lmna(-/-) cardiomyocytes with osmotic stress was reduced by addition of alpha-SMA-specific fusion peptide. Our findings support a model in which uncoupling of the nucleus and cytoskeleton associated with disruption of the LINC complex promotes mechanical instability and defective force transmission in cardiomyocytes. Changes in the distribution and expression patterns of nuclear and cytoskeletal actin suggest that diverse transcriptional and structural defects may also contribute to DCM in Lmna(-/-) mice. (C) 2010 Elsevier Ltd. All rights reserved.