核修饰基因与氨基糖甙类药物在母系遗传性聋发病机制及功能研究

Mechanism and Functional Research on Nuclear Modified Gene Associated with Maternally Inherited Aminoglycoside-Induced Deafness

目的对同时存在线粒体DNA 12S rRNA基因突变(A1555G突变)和存在个体表现出对氨基糖甙类药物不敏感的家系进行系统的资料收集和分子机制分析工作。方法对此家系进行体格检查、耳鼻咽喉专科检查、听力学检查,并对此家系进行线粒体DNA测定、线粒体单体型分型、氨基糖甙类药物敏感性检测、线粒体DNA相关核修饰基因TRMU和MTO1等研究。结果通过对全体成员的线粒体DNA序列测序分析,该家系的母系成员均有同质性A1555G突变;线粒体单体型分析为D5b1b;对发现的氨基糖甙类药物不敏感成员及家系中另一敏感成员行核基因TRMU和MTO1测序序列分析,对比发现MTO1基因变异:74202000_74202001insG和74202003delG,而TRMU基因未发现有意义的突变。结论线粒体DNA 12S rRNA基因突变家系中,存在对氨基糖甙类药物不敏感个体,MTO1为可能的核修饰基因,但其分子机制需要进一步深入研究。

Objective To study the molecular genetics and cell functions of non-sensitivity to aminoglycosides and to an- alyze the molecular mechanism in a family with maternally transmitted aminoglycoside-induced non-syndromic deafness. Methods A clinical,molecular,genetic and phylogenic analysis in this Chinese family was performed. Results Sequence analy- sis of mitochondrial DNA in this pedigree identified a homoplastic A-to-G transition at position 1555 （A1555G） in the 12S rRNA gene. Analysis of the complete mtDNA genome revealed that this family belonged to haplotype D5blb and exhibited high penetrance in contrast with other reported families. There was a variation found in the MTO1 gene： 74202000_ 74202001insG and 74202003delG, indicating that the MTO1 gene may be the nuclear modified gene in this family. There was no significant mutation in the TRMU gene. Exposure to a high concentration of aminoglycosides caused an increase in dou- bling time in lymphoblastoid cell lines derived from one symptomatic individual in this family, while the doubling time of the cell lines from the asymptomatic individual didn＇ t increase. Conclusion These results suggest that the nuclear background plays a role in the aminoglycoside ototoxicity and in the development of the deafness phenotype associated with the A1555G mutation in the mitochondrial 12S rRNA gene.