State Key Laboratory of Cardiovascular Disease, Physiology and Pathophysiology Laboratory, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 167 Bei-Li-Shi Road, Xi-Cheng District, Beijing 100037, P.R. China.
Department of Biophysics, School of Basic Medical Sciences, Peking University, 38 Xue-Yuan Road, Hai-Dian District, Beijing 100191, P.R. China.
Europace. 2016 Apr;18(4):617-22. doi: 10.1093/europace/euv044. Epub 2015 Mar 31.
Two LMNA mutations (R644C and R190W) have been associated with familial and sporadic left ventricular non-compaction (LVNC). However, the mechanisms underlying these associations have not been elucidated.
Genomic DNA was isolated from peripheral blood leucocytes and analysed by direct sequencing. Human embryonic kidney 293 cells were transfected with either wild type or mutant LMNA and SCN5A for whole-cell patch-clamp experiment and fluorescence microscopy. Point mutation modeling for mutant LMNA was also performed. One novel LVNC-associated mutation (V445E) in β2 sheet of immunoglobulin (Ig)-like fold was found in the proband and his father. We also found that the peak current of sodium channel was markedly reduced in mutant LMNA compared with WT while the activation, inactivation, and recovery curves were not significantly altered. The mutant lamin A/C were aggregated into multiple highlighted particles. Three β sheets and multiple side chains in Ig-like fold were altered due to the replacement of a valine by glutamic acid.
Our data associated a novel lamin A/C mutation (V445E) with a sudden death form of familial LVNC. The reduced sodium current in mutant LMNA may account for the advent of malignant ventricular arrhythmias. The altered structures of three β sheets and side chains may partially explain the aggregation of lamin A/C protein subjacent to the nuclear envelope.
两种 LMNA 突变（R644C 和 R190W）与家族性和散发性左心室致密化不全（LVNC）有关。然而，这些关联的机制尚未阐明。
从外周血白细胞中提取基因组 DNA，并通过直接测序进行分析。用野生型或突变型 LMNA 和 SCN5A 转染人胚肾 293 细胞，进行全细胞膜片钳实验和荧光显微镜检查。还对突变型 LMNA 进行了点突变建模。在先证者及其父亲中发现了一种新的与 LVNC 相关的突变（V445E），位于免疫球蛋白（Ig）样折叠的β2 片层中。我们还发现，与 WT 相比，突变型 LMNA 的钠通道峰值电流明显降低，而激活、失活和恢复曲线没有明显改变。突变型 lamin A/C 聚集成多个高亮粒子。由于缬氨酸被谷氨酸取代，Ig 样折叠中的三个β片层和多个侧链发生改变。
我们的数据将一种新的 lamin A/C 突变（V445E）与家族性 LVNC 的猝死形式联系起来。突变型 LMNA 中的钠电流减少可能是恶性室性心律失常发生的原因。三个β片层和侧链的结构改变可能部分解释了核膜下 lamin A/C 蛋白的聚集。
