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Upon escaping the mitochondria and entering the nucleus, it can act as a substrate for histone acetylation. [9] Histone acetylation is an epigenetic modification, which leads to gene activation. At a young age, acetyl-CoA levels are higher in the nucleus and cytosol, and its transport to the nucleus can extend lifespan in worms. [10] [11]
In mice, when catalase expression is increased specifically in mitochondria, oxidative DNA damage (8-OHdG) in skeletal muscle is decreased and lifespan is increased by about 20%. [39] [40] These findings suggest that mitochondria are a significant source of the oxidative damages contributing to aging. [citation needed]
Mitochondrial DNA is the small circular chromosome found inside mitochondria. These organelles, found in all eukaryotic cells, are the powerhouse of the cell. [1] The mitochondria, and thus mitochondrial DNA, are passed exclusively from mother to offspring through the egg cell.
The theory implicates the mitochondria as the chief target of radical damage, since there is a known chemical mechanism by which mitochondria can produce ROS, mitochondrial components such as mtDNA are not as well protected as nuclear DNA, and by studies comparing damage to nuclear and mtDNA that demonstrate higher levels of radical damage on ...
Evidence suggests that mitochondria can also undergo fusion and exchange (in a form of crossover) genetic material among each other. Mitochondria sometimes form large matrices in which fusion, fission, and protein exchanges are constantly occurring. mtDNA shared among mitochondria (despite the fact that they can undergo fusion). [citation needed]
These faulty mitochondria can further deplete the cell of ATP, increase production of ROS, and release proapoptopic proteins such as caspases. Because of the danger of having damaged mitochondria in the cell, the timely elimination of damaged and aged mitochondria is essential for maintaining the integrity of the cell.
In aged adults, each copy of mitochondrial DNA has on average 3.3 mutations changing protein structure. This exceeds previous estimates by more than three orders of magnitude. The discovery of microheteroplasmy lends support to the mitochondrial theory of aging, and has already been linked to the causation of Parkinson's disease. [7]
A mitochondrion (pl. mitochondria) is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. [2]