Axonal mitochondria regulate gentle touch response through control of axonal actin dynamics.

Actin in neuronal processes is both stable and dynamic. The origin & functional roles of the different pools of actin is not well understood. We find that mutants that lack mitochondria, ric-7 and mtx-2; miro-1 , in neuronal processes also lack dynamic actin. Mitochondria can regulate actin dynamics upto a distance ∼80 μm along the neuronal process. Absence of axonal mitochondria and dynamic actin does not markedly alter the Spectrin Membrane Periodic Skeleton (MPS) in touch receptor neurons (TRNs). Restoring mitochondria inTRNs cell autonomously restores dynamic actin in a sod-2 dependent manner. We find that dynamic actin is necessary and sufficient for the localization of gap junction proteins in the TRNs and for the C. elegans gentle touch response. We identify an in vivo mechanism by which axonal mitochondria locally facilitate actin dynamics through reactive oxygen species that we show is necessary for electrical synapses & behaviour.