Fig. P1.

(A) Individual mitochondria labeled in red are found in a neurite. In addition, many mitochondria are found in the neuronal cell body. (B) Distribution of mitochondria (red) in a WT neuron. (Inset) Mitochondria of various shapes are localized in the growth cone, neurite, and cell body. (C) Summary of experiments resulting in reduced mitochondrial size and clearance of mitochondria from growth cones and neurites, including G-actin elevation (via actin R62D), loss of SRF, expression of aggregation-competent huntingtin or inactive cofilin, application of the actin-depolymerization toxin latrunculin, and stimulation of neurons with ephrin-A5. (D) Summary of experiments resulting in enhanced mitochondrial size and increased numbers of mitochondria in growth cones and neurites, including F-actin elevation (via actin G15S), SRF-VP16 activity, expression of active cofilin S3A or its activating phosphatase slingshot, and stimulation of neurons with BDNF.