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. Author manuscript; available in PMC: 2018 Apr 1.
Published in final edited form as: Exerc Sport Sci Rev. 2017 Apr;45(2):58–69. doi: 10.1249/JES.0000000000000101

Figure 1. Mitochondrial Regulated Sarcopenia.

Figure 1

Induction of mitochondrial stress (lightning bolt) can result in dysfunctional mitochondria. Damaged mitochondria are engulfed in an autophagosome membrane and removed by mitophagy signaling in healthy young muscle and motor neurons. However, aging is associated with increased ROS and other mitochondrial stresses, which enhance mPTP opening. Release of the mitochondrial contents to the cell cytosol induces an apoptotic cascade ending with DNA fragmentation and removal of nuclei. Sufficient nuclear death in muscle cells will result in the death and removal of the entire muscle cell. Similarly, motor neuron death occurs when apoptosis removal of the alpha motor neuron nucleus occurs. The interdependence of muscle cells and motor neurons suggests a potential feedback loop (anterograde and retrograde) communication between the muscle and the motor neuronal compartments, which exacerbates death in both compartments. Death in these cell compartments leads to loss of muscle mass and function in aging. Thus, dysfunctional mitochondria provide the signal to initiate sarcopenia.