TGF-β/Smad3 signaling is activated during zebrafish ventricular regeneration. (A–G′) Whole-mount in situ hybridization showing that the expression of components of the TGF-β signaling pathway, tgfb1a, tgfb1b, tgfb2, tgfb3, alk5a, alk5b, and smad3a, was upregulated in the ablated hearts (A′–G′) compared with that in the control hearts (A–G) at 5 dpf/2 dpt. Dashed lines outline the hearts. (H–H′) Representative immunostaining images of Tg(vmhc:mCherry-NTR) hearts showing that phospho-Smad3 signal was increased in the ablated hearts (H′) than in the control hearts (H) at 5 dpf/2 dpt. Green, anti-pSmad3; red, MF20 (anti-MHC). (I) Quantification of phospho-Smad3-positive cells in the control and ablated hearts at 5 dpf/2 dpt (N = 8 and 11, respectively). Mean ± s.e.m., Student’s t-test, two-tailed, ****P < 0.0001. Scale bars, 50 μm. dpf, days post-fertilization; dpt, days post-treatment; atr., atrium; oft., out flow tract; vent., ventricle.
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