Asymmetric mitochondrial trafficking balances perinuclear biogenesis to maintain network morphology

In functionally polarized cells, mitochondria can form distinct subpopulations, positioned at sites of varying metabolic and energetic demands. Thus far, the potential presence of such subpopulations and implications of their intracellular trafficking in immobile and proliferative cells remain largely undescribed, despite such cells serving as key models. Here, we use substrate micropatterning to create reproducible morphologies of cultured immortalized cells, enabling us to define mitochondrial subpopulations and follow their trafficking by photoactivation. We discovered that mitochondrial material is dispersed asymmetrically throughout the cell via biased anterograde transport from the perinuclear area. Combining quantitative analysis and in silico modeling, we characterize the causes and consequences of unbalanced mitochondrial trafficking. Our findings indicate that this bias is required to distribute new material resulting from perinuclear mitochondrial biosynthesis to sustain mitochondrial mass distribution across the cell and to maintain normal network connectivity.