The Heart Has High Energy Needs, Making it Vulnerable to Age-Related Mitochondrial Dysfunction

Not all tissues are equal in their energy needs. The brain and more consistently active muscles, such as the heart, are at the top of the list. Energy for cell and tissue processes is provided by the chemical energy store molecule adenosine triphosphate (ATP), which is produced by mitochondria. Every cell contains hundreds of mitochondria, the descendants of ancient symbiotic bacteria now evolved to become fully integrated cell components. Mitochondria still replicate much like bacteria, each containing a small remnant circular genome. When damaged or dysfunctional, mitochondria are cleared by the complex process of mitophagy, a mitochondrially targeted form of autophagy that recognizes impaired mitochondria and ensures that they are transported to a lysosome for disassembly. Unfortunately, mitochondria become dysfunctional with age in ways that can (a) promote inflammation, such as via escape of mitochondrial DNA into the cytoplasm where it can trigger defenses that evolved to identify bacterial DNA, and (b) reduce ATP production. Epigenetic changes affect the dynamics of mitochondrial fusion and fission in ways that impair mitophapy. Similarly, epigenetic change leads to a decline in autophagy in general with age. Worn and damaged mitochondria accumulate as a result. Further, mitochondrial DNA is less well protected and repaired than is the case for nuclear DNA. Damage to mitochondrial DNA can disrupt ATP production and in extreme cases produce broken mitochondria th...
Source: Fight Aging! - Category: Research Authors: Tags: Medicine, Biotech, Research Source Type: blogs