Fig. 3.

SRF-VP16 induces mitochondrial network formation and alters transport parameters. In WT neurons, constitutively active SRF-VP16–induced mitochondrial networks (B, F, and J) compared with SRF-ΔMADS-VP16–expressing neurons (A, E, and I) are shown. (C, G, and K) In an Srf mutant neuron, mitochondria accumulate around the cell body. (D, H, and L) SRF-VP16 expression in Srf mutant neurons increased mitochondrial object size and neurite occupancy. (M–P) Kymographs depict distance traveled by mitochondria (white bars) within 5 min. SRF-VP16 in WT neurons increased the number and velocity of moving mitochondria (N) compared with an SRF-ΔMADS-VP16–expressing neuron (M). On SRF ablation, mitochondria fail to move (O), a phenotype alleviated by SRF-VP16 (P). SRF-VP16 but not CREB-VP16 changed object size (Q) and occupancy (R). ko, knockout; wt, wild type. (S and T) SRF-VP16 increased the velocity and percentage of mitochondria being transported. (*P < 0.05.) Numbers in bars represent numbers of independent experiments. (Scale bar: A–L, 10 μm.)