The objective of this proposed research is to define the role of mitochondrial leucyl-tRNA synthetase and elongation factor TU (EFTU) in the pathogenesis of mutations in the tRNALeu (UUR) that are commonly related to human diseases. This second goal of this study is to explore a way to therapeutically intervene for maternally inherited disease by over-expression of these two proteins in the cybrids carrying pathogenic mutations in the tRNA Leu (UUR). A variety of mitochondrial DNA (mtDNA) mutation have been found to be associated with many clinical abnormalities, including neuromuscular disorders. Of the 100 pathogenic point mutations in mtDNA, >70 occur in tRNA genes. Of these, the most common mutation is the A to G transition at position 3243 (A3243G) in the tRNALeu (UUR) gene, which causes mitochondrial encephalomyopathy, lactic acidosis, stroke-like symptoms (MELAS) and other disorders. Mitochondria with this mutated tRNA exhibited a reduced ATP production, which results from quantitative deficiencies in mitochondrial protein synthesis. We hypothesize that the over-expression of human mitochondrial leucyl-tRNA synthetase and EFTU in the disease cell model of the A3243G mutation in the tRNALeu (UUR) gene will correct the mitochondrial translational defects, consequently increasing the level of ATP production. This application proposes two specific aims: 1). Construction of the stably transfected cell lines through transferring human mitochondrial leucyl-tRNA synthetase and EFTU cDNAs into the cybrid cell lines carrying the A3243G mutation and wild type mtDNA. 2). These stably transfected cell lines will be evaluated for the correction of mitochondrial dysfunction by using biochemical and metabolic assays. Success of this protection will define the role of the mitochondrial leucyl-tRNA synthetase and EFTU in the pathogenesis of mutations in the tRNALeu(UUR) gene associated with human diseases. This should provide new insights into the molecular mechanism of maternally inherited disorders. In particular, success in the aim of correcting the biochemical defect associated with A3243G mutation in the tRNA Leu (UUR) gene by overexpressing mitochondrial leucyl-tRNA synthetase, will open the way to therapeutic interventions for maternally inherited diseases. In the long term, fundamental experimental approaches and knowledge, which results from this proposed work would be applicable to many other tRNA gene mutations, associated diseases in humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS044015-02
Application #
6619453
Study Section
Special Emphasis Panel (ZRG1-MDCN-2 (01))
Program Officer
Gwinn, Katrina
Project Start
2002-08-01
Project End
2005-07-31
Budget Start
2003-08-01
Budget End
2004-07-31
Support Year
2
Fiscal Year
2003
Total Cost
$175,750
Indirect Cost
Name
Cincinnati Children's Hospital Medical Center
Department
Type
DUNS #
071284913
City
Cincinnati
State
OH
Country
United States
Zip Code
45229
Li, Ronghua; Guan, Min-Xin (2010) Human mitochondrial leucyl-tRNA synthetase corrects mitochondrial dysfunctions due to the tRNALeu(UUR) A3243G mutation, associated with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like symptoms and diabetes. Mol Cell Biol 30:2147-54
Liang, Min; Guan, Minqiang; Zhao, Fuxing et al. (2009) Leber's hereditary optic neuropathy is associated with mitochondrial ND1 T3394C mutation. Biochem Biophys Res Commun 383:286-92
Liu, Yuqi; Li, Ronghua; Li, Zongbin et al. (2009) Mitochondrial transfer RNAMet 4435A>G mutation is associated with maternally inherited hypertension in a Chinese pedigree. Hypertension 53:1083-90
Tong, Yi; Mao, Yijian; Zhou, Xiangtian et al. (2007) The mitochondrial tRNA(Glu) A14693G mutation may influence the phenotypic manifestation of ND1 G3460A mutation in a Chinese family with Leber's hereditary optic neuropathy. Biochem Biophys Res Commun 357:524-30
Jin, Longjin; Yang, Aifen; Zhu, Yi et al. (2007) Mitochondrial tRNASer(UCN) gene is the hot spot for mutations associated with aminoglycoside-induced and non-syndromic hearing loss. Biochem Biophys Res Commun 361:133-9
Wei, Qi-Ping; Zhou, Xiangtian; Yang, Li et al. (2007) The coexistence of mitochondrial ND6 T14484C and 12S rRNA A1555G mutations in a Chinese family with Leber's hereditary optic neuropathy and hearing loss. Biochem Biophys Res Commun 357:910-6
Liao, Zhisu; Zhao, Jianyue; Zhu, Yi et al. (2007) The ND4 G11696A mutation may influence the phenotypic manifestation of the deafness-associated 12S rRNA A1555G mutation in a four-generation Chinese family. Biochem Biophys Res Commun 362:670-6
Chen, Jianfu; Yang, Li; Yang, Aifen et al. (2007) Maternally inherited aminoglycoside-induced and nonsyndromic hearing loss is associated with the 12S rRNA C1494T mutation in three Han Chinese pedigrees. Gene 401:4-11
Qu, Jia; Li, Ronghua; Zhou, Xiangtian et al. (2007) Cosegregation of the ND4 G11696A mutation with the LHON-associated ND4 G11778A mutation in a four generation Chinese family. Mitochondrion 7:140-6
Yuan, Huijun; Chen, Jing; Liu, Xin et al. (2007) Coexistence of mitochondrial 12S rRNA C1494T and CO1/tRNA(Ser(UCN)) G7444A mutations in two Han Chinese pedigrees with aminoglycoside-induced and non-syndromic hearing loss. Biochem Biophys Res Commun 362:94-100

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