Biochemical characterization of the mitochondrial tRNASer(UCN) T7511C mutation associated with nonsyndromic deafness
Biochemical characterization of the mitochondrial tRNASer(UCN) T7511C mutation associated with nonsyndromic deafness
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DOI：
10.1093/nar/gkh226
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发表时间：
2004-02-01
影响因子：
14.9
通讯作者：
Guan, MX
中科院分区：
文献类型：
--
作者：
Li, XM;Fischel-Ghodsian, N;Guan, MX
我们在这里报告了耳聋相关线粒体tRNA(Ser(UCN))T7511C突变以及同质ND1 T3308C和tRNA(Ala)T5655C突变的生化特征，这些突变是通过将来自非洲家庭的淋巴母细胞系的线粒体转移到无mtDNA(Rho(O))的细胞而构建的。三个来自携带同质T7511C突变的受影响的母系亲属的胞质，与三个对照胞体相比，tRNA(Ser(UCN))水平下降了75%。TRNA(Ser(UCN))水平的这一降低量低于建议的阈值，以支持淋巴母细胞系线粒体蛋白质合成的正常速率。这一缺陷可能是导致线粒体蛋白质合成速度降低52%，以及在含半乳糖的培养液中呼吸和生长特性明显缺陷的主要原因。有趣的是，T5655C突变使突变细胞中的tRNA(ALA)水平降低了50%。值得注意的是，T3308C突变导致突变细胞中ND1mRNA和共转录tRNA(Leu(UUR))的数量显著减少。因此，T5655C和T3308C突变引起的线粒体功能障碍可能影响T7511C突变的表型表现。这些观察结果表明，T7511C突变和两个mtDNA突变的组合解释了该家族中高外显性耳聋的原因。
We report here the biochemical characterization of the deafness-associated mitochondrial tRNA(Ser(UCN)) T7511C mutation, in conjunction with homoplasmic ND1 T3308C and tRNA(Ala) T5655C mutations using cybrids constructed by transferring mitochondria from lymphoblastoid cell lines derived from an African family into human mtDNA-less (rho(o)) cells. Three cybrids derived from an affected matrilineal relative carrying the homoplasmic T7511C mutation, exhibited similar to75% decrease in the tRNA(Ser(UCN)) level, compared with three control cybrids. This amount of reduction in the tRNA(Ser(UCN)) level is below a proposed threshold to support a normal rate of mitochondrial protein synthesis in lymphoblastoid cell lines. This defect is likely a primary contributor to similar to52% reduction in the rate of mitochondrial protein synthesis and marked defects in respiration and growth properties in galactose-containing medium. Interestingly, the T5655C mutation produces similar to50% reduction in the tRNA(Ala) level in mutant cells. Strikingly, the T3308C mutation causes a significant decrease both in the amount of ND1 mRNA and co-transcribed tRNA(Leu(UUR)) in mutant cells. Thus, mitochondrial dysfunctions caused by the T5655C and T3308C mutations may modulate the phenotypic manifestation of the T7511C mutation. These observations imply that a combination of the T7511C mutation with two mtDNA mutations accounts for the high penetrance of deafness in this family.