A high mutation load of m.14597A>G in MT-ND6 causes Leigh syndrome

Abstract Leigh syndrome (LS) is an early-onset progressive neurodegenerative disorder associated with mitochondrial deficiency. m.14597A>G (p.Ile26Thr) in the MT-ND6 gene was reported to cause Leberʼs hereditary optic neuropathy (LHON) or dementia/dysarthria. In previous reports, less than 90% he...

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Autores principales: Yoshihito Kishita, Kaori Ishikawa, Kazuto Nakada, Jun-Ichi Hayashi, Takuya Fushimi, Masaru Shimura, Masakazu Kohda, Akira Ohtake, Kei Murayama, Yasushi Okazaki
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Lenguaje:EN
Publicado: Nature Portfolio 2021
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Acceso en línea:https://doaj.org/article/2a76a814c3ba4c25adefbc26eb47bb7d
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Sumario:Abstract Leigh syndrome (LS) is an early-onset progressive neurodegenerative disorder associated with mitochondrial deficiency. m.14597A>G (p.Ile26Thr) in the MT-ND6 gene was reported to cause Leberʼs hereditary optic neuropathy (LHON) or dementia/dysarthria. In previous reports, less than 90% heteroplasmy was shown to result in adult-onset disease. Here, by whole mitochondrial sequencing, we identified m.14597A>G mutation of a patient with LS. PCR–RFLP analysis on fibroblasts from the patient revealed a high mutation load (> 90% heteroplasmy). We performed functional assays using cybrid cell models generated by fusing mtDNA-less rho0 HeLa cells with enucleated cells from patient fibroblasts carrying the m.14597A>G variant. Cybrid cell lines bearing the m.14597A>G variant exhibited severe effects on mitochondrial complex I activity. Additionally, impairment of cell proliferation, decreased ATP production and reduced oxygen consumption rate were observed in the cybrid cell lines bearing the m.14597A>G variant when the cells were metabolically stressed in medium containing galactose, indicating mitochondrial respiratory chain defects. These results suggest that a high mutation load of m.14597A>G leads to LS via a mitochondrial complex I defect, rather than LHON or dementia/dysarthria.