Mitochondrial distribution in neurons: Interplay of transport and morphology

Neurons consist of a small cell body (soma) and several extended projections (axons and dendrites). To maintain neuronal health, organelles and other components derived from the soma must be optimally distributed through this extensive morphology. Mitochondria navigate the tree-like branched geometry of neuronal dendrites through bidirectional active transport and regulated stopping. In dendritic trees of the Drosophila visual system, mitochondrial densities increase with distance from the soma. Despite spatial heterogeneity in mitochondrial density and subtree morphology, sister subtrees have balanced total mitochondrial densities. Using mathematical modeling, we show that specific scaling laws for dendritic branching patterns enable robust self-organization of the mitochondrial population for a range of transport behaviors, to maintain equitable distribution across subtrees while still allowing for increased densities at distal tips. Our theoretical predictions are validated by experimental measurements of dendritic structure and mitochondrial transport, demonstrating that the scaling laws are observed in the dendritic trees of the Drosophila visual system.