A Double Heterozygous Mutation of TNNI3 Causes Hypertrophic Cardiomyopathy in a Han Chinese Family.
A Double Heterozygous Mutation of TNNI3 Causes Hypertrophic Cardiomyopathy in a Han Chinese Family.
复制标题
TNNI3 双杂合突变导致汉族家庭肥厚型心肌病。
作者：
Zheng Hua;Huang Huajie;Ji Zhisong;Yang Qi;Yu Qiuxia;Shen Fan;Liu Cuixian;Xiong Fu
目的探讨一个中国汉族肥厚型心肌病（HCM）家系TNNI 3基因的变异及其与HCM发病的分子机制。采用生物信息学、亚细胞定位测定和Western blotting方法对TNNI 3突变的病理生理机制进行了研究。235 C> T和C。470 C> T，位于TNNI 3基因的外显子4和6。先证者（II-2）和她的兄弟（II-1）先前被诊断为HCM，携带两种突变，而他们的健康父母只携带1种。TNNI 3氨基酸序列的比对表明，这两个Pro残基在物种间高度保守。亚细胞定位表明，野生型（WT）和突变体TNNI 3蛋白定位在细胞核。Western blot分析人胚肾293 T细胞中的表达显示，与WT TNNI 3相比，突变蛋白的细胞内水平显著降低（p< 0.01）。这些结果将启发进一步研究TNNI 3基因与HCM之间的联系。
ObjectivesTo investigate the variations in the TNNI3 gene in a Chinese Han family affected by hypertrophic cardiomyopathy (HCM) and the potential molecular mechanism linking these mutations with disease.MethodsPeripheral venous blood was acquired from family members, and TNNI3 mutations were identified by DNA sequencing. The pathophysiology of TNNI3 mutations was investigated using bioinformatics, subcellular localization determination and Western blotting.ResultsSanger sequencing revealed that the proband possessed 2 heterozygous mutations, c. 235C> T and c. 470C> T, located at exons 4 and 6 of the TNNI3 gene. The proband (II-2) and her brother (II-1), who had been previously diagnosed with HCM, harbored both mutations whereas their healthy parents harbored only 1. Alignment of the TNNI3 amino acid sequence indicated that the two Pro residues were highly conserved across species. Subcellular localization showed that both wild-type (WT) and mutant TNNI3 proteins were localized at the cell nucleus. Western blot analysis of expression in human embryonic kidney 293T cells showed that the intracellular levels of the mutant proteins were significantly decreased compared to WT TNNI3 (p< 0.01).ConclusionsOur findings showed that a double heterozygous mutation in the TNNI3 gene is involved in the pathogenesis of HCM via haploinsufficiency. These results will inspire further studies to investigating the link between the TNNI3 gene and HCM.