Mitochondria possess their own DNA and transcription and translation machinery for the synthesis of 13 protein subunits for the oxidative phosphorylation system, two rRNAs and 22 tRNAs. In 1988 the first human neurodegenerative diseases associated with mutations in the mitochondrial genome were described. The most recent biochemical and genetic research suggests that mitochondrial disorders are best categorized as: (i) primary mutations of the mitochondrial DNA, either sporadic or maternally inherited; (ii) nuclear mutations that result in alterations in mitochondrial DNA or intergenomic signalling defects; or (iii) Mendelian defects that affect the respiratory chain in the absence of mitochondrial DNA mutations. There is still little information about the pathophysiology of these different disorders. In order to obtain some insight into the cellular mechanisms of neurodegeneration, we examined cultured fibroblasts from patients with the MELAS (mitochondrial encephalopathy, lactic acidosis and stroke-like episodes) syndrome, which is most frequently caused by a mutation in the mitochondrial tRNA for leucine. We found that their basal level of ionized calcium was elevated and that they could not normally sequester calcium influxes induced by depolarization. In addition, they were unable to maintain normal mitochondrial membrane potentials, as determined using a voltage-sensitive fluorescent indicator. Despite these physiological perturbations, the MELAS fibroblasts had normal concentrations of ATP. If neurons in MELAS patients have similar physiological abnormalities, their functional properties and long-term viability may be compromised.
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September 1999
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Conference Article|
September 01 1999
Mutations of the mitochondrial genome: clinical overview and possible pathophysiology of cell damage
Steven M. Rothman
Steven M. Rothman
1
1Departments of Neurology and Pediatrics, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, U.S.A.
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Publisher: Portland Press Ltd
Online ISSN: 1744-1439
Print ISSN: 0067-8694
© 1999 The Biochemical Society
1999
Biochem Soc Symp (1999) 66: 111–122.
Citation
Guy C. Brown, David G. Nicholls, Chris E. Cooper, Steven M. Rothman; Mutations of the mitochondrial genome: clinical overview and possible pathophysiology of cell damage. Biochem Soc Symp 1 September 1999; 66 111–122. doi: https://doi.org/10.1042/bss0660111
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