Fig. 5

Fig. 5

Expression of emGFP-lgf2bp1^Y399E in RGCs disrupts axon outgrowth in vivo.

(a-c) Dorsal confocal projections (30x silicone immersion lens) of Tg(isl2b:emGFP) (a), Tg(isl2b:emGFP-Igf2bp1)^wt (b), and Tg(isl2b:emGFP-Igf2bp1)^Y399E (c) 3 dpf transient transgenic embryos. (d) Quantification of the ratio of emGFP (green) positive RGCs in the retina to emGFP positive axons on the contralateral tectum per tectum-eye pair (average +/- SEM). A one-way ANOVA (p<0.0001) with a Tukey HSD test (p<0.01) showed that the ratios were significantly different in emGFP-Igf2bp1^Y399E (N = 16 tectum-eye pairs, 9 animals) compared to Igf2bp1^wt (N = 11 tectum-eye pairs in 7 animals) and emGFP (N = 26 tectum-eye pairs, 16 animals) controls, and controls were not significantly different. (e) Schematic of the predicted mechanism for Igf2bp1^Y399E expression preventing axon outgrowth by interfering with endogenous Igf2bp1 by competing for mRNA transport to the growth cone without β-actin mRNA cargo, therefore decreasing the amount of β-actin mRNA available for local translation in the growth cone in response to attractive guidance cues. (f-k) Dorsal confocal projections of Tg(isl2b:emGFP (f-h) and Tg(isl2b:emGFP-Igf2bp1^Y399F) (i-k) 3 dpf embryos. Scale bars are 100 µm.