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Optimal Dynamics for Quality Control in Spatially Distributed Mitochondrial Networks

Figure 3

Maintenance of a healthy mitochondrial population requires autophagy and is enhanced by fusion and fission.

(A) In the presence of damage alone, average mitochondrial health (red) decays exponentially. The dashed lines represent the 25th and 75th percentiles of health averaged over 25 independent simulations, while the shaded region represents one standard deviation above and below the average health across the simulations. The population size (blue) remains constant. (B) With the addition of autophagy, which removes mitochondria below an autophagy threshold of (gray region), the average steady-state health initially decreases more slowly than in (A), before the decreasing number of mitochondria reduces the population density to a level that makes it impossible to maintain health. The wide range of healths near this transition point is due to the small numbers of mitochondria per cell. (C) The addition of replication rescues the population size and health to a value just above the autophagy threshold. (D) The further inclusion of fusion, for mitochondria above a fusion threshold , and fission increases the average steady-state health of the mitochondrial population. The variability in health increases due to the stochastic nature of the asymmetric exchange of HUs during fission.

doi: https://doi.org/10.1371/journal.pcbi.1003108.g003