Scientists from the Montreal Neurological Institute and Hospital in Canada have discovered that two
genes1 linked to
hereditary2（遗传的） Parkinson's disease are involved in the early-stage quality control of
mitochondria（线粒体）. The protective
mechanism3, which is reported in The EMBO Journal, removes damaged proteins that arise from oxidative stress from mitochondria. "PINK1 and parkin, are
implicated4 in selectively targeting dysfunctional
components5 of mitochondria to the lysosome under conditions of excessive oxidative damage within the
organelle（细胞器）," said Edward Fon, Professor at the McGill Parkinson Program at the Montreal Neurological Institute and Hospital. "Our study reveals a quality control mechanism where vesicles bud off from mitochondria and proceed to the lysosome for
degradation6. This method is distinct from the degradation pathway for damaged whole mitochondria which has been known for some time. It is also an early response,
proceeding7 on a timescale of hours instead of days."
The
deterioration8 of
mechanisms9 designed to maintain the integrity and function of mitochondria throughout the lifetime of a cell has been suggested to
underlie10 the progression of several neurodegenerative diseases, including Parkinson's disease. When mitochondria, the "power plants" of the cell that provide energy,
malfunction11 they can contribute to Parkinson's disease. If they are to survive and function mitochondria need to degrade oxidized and damaged proteins.
In the study, immunofluorescence and confocal microscopy were used to observe how the vesicles "pinch off" from mitochondria with their damaged
cargo12. "Our conclusion is that the loss of this PINK1 and parkin-dependent trafficking system
impairs13 the ability of mitochondria to selectively degrade oxidized and damaged proteins and leads, over time, to the mitochondrial dysfunction
noted14 in hereditary Parkinson's disease," said Heidi McBride, Professor in the Neuromuscular Group in the Department of Neurology and Neurosurgery at the Montreal Neurological Institute and Hospital.
Both
salvage15 pathways are operational in the cell. If the vesicular pathway, the first line of
defense16, is overwhelmed and the damage is irreversible then the entire organelle is targeted for degradation.
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