Figure 3.

Light-induced activation of TrkA promotes neurite growth in PC12 cells in the absence of NGF. PC12 cells were subjected to continuous blue light illumination at 200 μW/cm² for 24 h. (A) PC12 cells expressing opto-full-TrkA and GFP displayed no obvious neurite growth. (B) Some PC12 cells expressing opto-Lyn-iTrkA and GFP extend short neurites. (C) Some PC12 cells expressing opto-iTrkA and GFP exhibit neurite growth. (D) Most PC12 cells expressing opto-iTrkA + CAAX grow long neurites. (E) PC12 expressing only CIBN-GFP-CAAX did not show noticeable neurite growth. (F) Quantification of percentage of cells with neurite growth for different systems. (G) Quantification of the length of the longest neurite in cells bearing neurites. (H) Quantification of the average number of neurite branches in cells bearing neurites. Results are averaged from three independent sets of experiments (detailed in Supplementary Table S1) and presented as mean ± SEM. Statistical analysis was performed using one-way ANOVA with Dunnett’s post hoc test. Student’s t test was used between dark or light cells under the same transfection conditions (*P < 0.05, **P < 0.005). Scale bars, 10 μm.