Hwu, P. T.; Kim, L. A.; Wood, M. A.; Thompson-Peer, K. L.

Mitochondria regulate cellular homeostasis in development and disease, and mitochondrial morphology plays a role in local injury signaling and wound repair. How mitochondria respond during dendrite injury remains an open fundamental question. Here we show that mitochondria contract rapidly and locally after laser dendrotomy. In the proximal intact dendrite, the extent of mitochondrial contraction diminishes with increasing distance from the injury site. We report that mitochondrial contraction is dependent on injury severity and that immediate contraction after injury results in a spatiotemporal increase in dendrite branching. Additionally, we find that mitochondrial contraction is inhibited by KCNJ2 (potassium inwardly rectifying channel subfamily J member 2), providing evidence that mitochondrial contraction is regulated by electrical activity. Mechanistically, we find that injury-induced mitochondrial contraction requires Drp1 (Dynamin related protein 1). In conclusion, these in-vivo findings characterize a dendrite response for mitochondria in neurons and provide insight into the regenerative outcomes of dendrites after injury.