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Human mitochondrial complex I dysfunction
J M Cooper1, V M Mann, D Krige
1Department of Neuroscience, Royal Free Hospital School of Medicine, London, UK.
Abstract:
In humans, complex I dysfunction has been observed in a high percentage of patients with mitochondrial myopathy. Analysis of mitochondria from these patients suggests the function and assembly of complex I is particularly susceptible to abnormalities of mitochondrial DNA, involving either point mutations of tRNA genes or major deletions. The evidence for a complex I defect in Parkinson's disease is accumulating, although the cause of this deficiency or the role it plays in the events that culminate in dopaminergic cell death remains unresolved.
Insights
Mitochondrial complex I dysfunction is common in mitochondrial myopathy due to mitochondrial DNA abnormalities. This defect is also increasingly linked to Parkinson's disease, but its exact cause and role in neurodegeneration are still unclear.
Area of Science:
- Biochemistry
- Neuroscience
- Genetics
Background:
- Complex I (NADH:ubiquinone oxidoreductase) is a crucial enzyme in the mitochondrial electron transport chain.
- Dysfunction of complex I is a hallmark of various mitochondrial myopathies.
- Accumulating evidence suggests a role for complex I defects in Parkinson's disease pathogenesis.
Purpose of the Study:
- To review the evidence linking complex I dysfunction to mitochondrial myopathies and Parkinson's disease.
- To highlight the susceptibility of complex I to mitochondrial DNA abnormalities.
- To discuss the unresolved questions regarding the cause and consequences of complex I deficiency in neurodegeneration.
Main Methods:
- Analysis of patient mitochondria.
- Review of existing literature on complex I function in disease.
Main Results:
- Complex I function and assembly are highly sensitive to mitochondrial DNA mutations (point mutations or deletions) in mitochondrial myopathies.
- A significant percentage of mitochondrial myopathy patients exhibit complex I dysfunction.
- Evidence for complex I deficiency in Parkinson's disease is growing.
Conclusions:
- Mitochondrial DNA abnormalities are a key factor in complex I dysfunction observed in mitochondrial myopathies.
- The precise mechanisms underlying complex I deficiency in Parkinson's disease and its contribution to dopaminergic cell death require further investigation.