摘要目的 研究探讨真核释放因子eRF3a的RNA干扰如何影响心脏钠通道无义突变的表达和功能.方法 构建心脏钠通道无义突变和干扰eRF3a RNA的真核表达载体,独立或共同转染HEK293细胞,全细胞膜片钳记录钠通道的表达电流和动力学,同时应用蛋白印迹和免疫荧光证明钠通道的表达和定位.结果 独立转染W822X无义突变的HEK293细胞没有检测到全长钠通道蛋白,表达的钠电流水平很低,仅相当野生型钠电流3%.共同转染HEK293细胞可以检测到全长钠通道蛋白,表达的钠电流水平明显增加,相当于野生型钠电流30%.免疫荧光也显示,独立转染W822X无义突变的HEK293细胞没有出现荧光细胞,而共同转染的HEK293细胞出现较多的荧光细胞.结论 真核释放因子eRF3a的RNA干扰促进心脏钠通道无义突变的翻译,部分恢复钠通道全长表达和功能.

abstractsObjective In this study we investigated the functional restoration of nonsense mutations in the SCN5A gene. Methods The readthrough-enhancing reagents were introduced to HEK293 cells to suppress one nonsense mutation W822X in the SCN5A gene. Patch-clamp was used to record the whole-cell current and dynamics. Western blot and immunofluorescence staining were used to certify the expression and the location of the sodium channel. Results In transfected HEK293 cells, the nonsense mutation in SCN5A inhibited the expression level of full-length protein, and the sodium currents from the mutant channels were less than 3% of the wild-type level. Readthrough enhancement by decreasing translation termination efficiency with a siRNA targeting eukaryotic release factor eRF3a ( a GTPase that binds eRF1 ), the sodium current from the mutant cDNAs was restored to as much as 30% of the wild-type. After the treatment by the readthrough-enhancing reagents, the channels from cDNA carrying W822X remained the features of wild-type phenotype, and Western blot and immunochemical staining also showed the expression of full-length channel proteins. Conclusion Readthrough-enhancing reagents could effectively suppress nonsense mutations in SCN5A and partially restore the function of sodium channel and the expression of full-length channels.