Mitochondria and neurodegeneration.

There is increasing evidence linking mitochondrial dysfunction to neurodegenerative diseases. Mitochondria are critical regulators of cell death, a key feature of neurodegeneration. Mutations in mitochondrial DNA and oxidative stress both contribute to ageing, which is the greatest risk factor for neurodegenerative diseases. This is the case in Alzheimer's disease, in which there is evidence that both beta-amyloid and the amyloid precursor protein may directly interact with mitochondria, leading to increased free radical production. In the case of Huntington's disease (HD), recent evidence suggests that the coactivator PGC1alpha, a key regulator of mitochondrial biogenesis in respiration, is down-regulated in patients with HD and in several animal models of this neurodegenerative disorder. In Parkinson's disease, the autosomal recessive genes parkin, DJ1 and PINK1 are all linked to either oxidative stress or mitochondrial dysfunction. In amyotrophic lateral sclerosis, there is strong evidence that mutant superoxide dismutase directly interacts with the outer mitochondrial membrane as well as the intermembrane space and matrix. Therefore, an impressive number of disease specific proteins interact with mitochondria. Therapies that target basic mitochondrial processes such as energy metabolism in free radical generation, or specific interactions of disease-related protein with mitochondria, hold great promise.