mTOR Inhibition Alleviates Mitochondrial Disease in a Mouse Model of Leigh Syndrome

More from mTOR Leigh syndrome is a rare, untreatable, inherited neurodegenerative disease in children that is caused by functional disruption of mitochondria, the cell's energy-producing organelles. Johnson et al. (p. 1524, published online 14 November; see Perspective by Vafai and Mootha) show that rapamycin, a drug used clinically as an immunosuppressant and for treatment of certain cancers, delayed the onset and progression of neurological symptoms in a mouse model of Leigh syndrome and significantly extended survival of the animals. Rapamycin inhibits the so-called “mTOR” signaling pathway, which is currently under intense study because it plays a contributory role in many common diseases. A drug in clinical use for other disorders delays progression of an untreatable mitochondrial disease in knockout mice. [Also see Perspective by Vafai and Mootha] Mitochondrial dysfunction contributes to numerous health problems, including neurological and muscular degeneration, cardiomyopathies, cancer, diabetes, and pathologies of aging. Severe mitochondrial defects can result in childhood disorders such as Leigh syndrome, for which there are no effective therapies. We found that rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR) signaling pathway, robustly enhances survival and attenuates disease progression in a mouse model of Leigh syndrome. Administration of rapamycin to these mice, which are deficient in the mitochondrial respiratory chain subunit Ndufs4 [NADH dehydrogenase (ubiquinone) Fe-S protein 4], delays onset of neurological symptoms, reduces neuroinflammation, and prevents brain lesions. Although the precise mechanism of rescue remains to be determined, rapamycin induces a metabolic shift toward amino acid catabolism and away from glycolysis, alleviating the buildup of glycolytic intermediates. This therapeutic strategy may prove relevant for a broad range of mitochondrial diseases.