Optimal Dynamics for Quality Control in Spatially Distributed Mitochondrial Networks
Figure 1
A cycle of fusion, fission, and autophagy contribute to quality control of mitochondrial health.
Each mitochondrion is represented as a set of discrete health units that are in either a healthy (green) or damaged (red) state. (1) Fusion joins two (or more) mitochondria into a connected entity, though each mitochondrion is assumed to retain its original identity. Only mitochondria above a particular health threshold are permitted to fuse. (2) Fused mitochondria undergo stochastic exchange of a fixed number of health units. This exchange can lead to an asymmetry in the health of fused mitochondria, which occurs when these mitochondria undergo fission. (3) Fission separates fused mitochondria into isolated mitochondria or mitochondrial subnetworks. (4) Autophagy removes isolated mitochondria when their health is below the autophagy threshold. (5) Damage to mitochondrial health sets a health unit to the damaged state. (6) New mitochondria are produced via the cumulative effects of protein synthesis and import, and this replication event generates a copy of an existing mitochondrion that appears in the same physical neighborhood with the same number of health units as the progenitor mitochondrion. The variables representing the rates of each process () are shown next to their labels.