Fig. 3

Zebrafish Nrf2 overexpression prevented human 4R-tau-GFP and zebrafish 3R-tau-GFP induced Neuronal death. a GFP-labeled neuronal cells and axons were observed at 24 and 48 hpf in embryos co-injected with pHuC-zNrf2-HA-2A-mCherry and pHuC-z3R-tau-GFP (b) or pHuC-h4R-tau-GFP (d). For comparison, embryos co-injected with pHuC-mCherry (panels a and c) were used as the control. The boxed regions are enlarged (a’-d”) to show the GFP-labeled neuronal cells in 24 and 48 hpf embryos from the lateral view. Scale bars: 100 μm. The protection effect of zNrf2 against neuronal death induced by human tau-GFP or zebrafish tau-GFP was presented in panel e to show higher percentage, 58 % and 55 % of zebrafish embryos expressing zNrf2 with more neuronal cells, compared to 19 % and 17 % without zNrf2. b GFP signals (panel a) and mCherry signals (panel a’) in neuronal cells and axons in embryos co-injected with pHuC-h4R-tau-GFP and pHuC-zNrf2-HA-2A-mCherry were colocalized (panel a”). Scale bar: 50 μm. c Double immunostaining of h4R-tau-GFP (GFP antibody) and zNrf2-HA (HA antibody, panel a’) in spinal cord neurons of the aforementioned zebrafish embryos. The phosphorylation state of h4R-tau-GFP was detected using antibody pT212 (panel b) and antibody AT8 (panel b’). Scale bar: 50 μm