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. 2023 Apr 19;12:e85902. doi: 10.7554/eLife.85902

Figure 7. Reduction of PKR mitigates antisense C4G2, but not sense G4C2, RNA- mediated toxicity in zebrafish.

(A) Schematic illustration of splice-blocking morpholino (SB-MO) targeting the exon 3/intron 3 junction in zebrafish eif2ak2 pre-mRNA. The correctly spliced (wild type transcripts) and intron 3 retained transcripts are shown. The translation-blocking morpholino targets the AUG start codon in post-spliced eif2ak2 mRNA. (B) SV2 immunostaining of motor axons in 30 hpf zebrafish embryos injected with GFP control mRNA and antisense (C4G2)70 RNAs. Scale bar = 50 µm. (C, D) Effects of SB-MO on axonal length (C) and branching (D) of zebrafish expressing antisense (C4G2)70 RNAs. Embryos were injected with 0.844 µM GFP mRNA, 0.844 µM antisense (C4G2)70 RNAs, 0.844 µM antisense (C4G2)70 RNAs plus 0.25 mM control morpholino, or 0.844 µM antisense (C4G2)70 RNAs plus 0.25 mM eif2ak2 morpholino. Error bars represent SD (n = 4 independent experiments). Statistical analyses were performed using one-way ANOVA with Tukey’s post hoc test. (E, F) Effects of SB-MO on axonal length and branching of zebrafish expressing sense (G4C2)70 RNAs. Embryos were injected with 0.844 µM GFP mRNA, 0.844 µc sense (G4C2)70 RNAs, 0.844 µM sense (G4C2)70 RNAs plus 0.25 mM control morpholino or 0.844 µM sense (G4C2)70 RNAs plus 0.25 mM eif2ak2 morpholino. Error bars represent SD (n = 4 independent experiments). Statistical analyses were performed using one-way ANOVA with Tukey’s post hoc test.

Figure 7.

Figure 7—figure supplement 1. Translation-blocking morpholino of PKR mitigates antisense C4G2 repeat RNA-induced axonopathy in zebrafish.

Figure 7—figure supplement 1.

(A) Dose-dependent knockdown of WT transcripts and increase of transcripts with intron 3 retention as determined by RT-PCR analysis. Eif2ak2 splice variants in non-injected, standard control and eif2ak2 targeting MO-injected embryos 30 hpf are shown. (B, C) Effect of translation-blocking morpholino (TB-MO)-mediated reduction of Eif2ak2 on axonal length (B) and branching (C), using a dose of 0.25 mM for TB-MO and standard control MO in GFP and antisense (C4G2)70 RNAs expressing zebrafish. Error bars represent SD (n = 4 independent experiments). Statistical analyses were performed using one-way ANOVA with Tukey’s post hoc test.
Figure 7—figure supplement 1—source data 1. Original agarose gel results for Figure 7—figure supplement 1A.