Fig. 5

Loss of Zfpm1 led to the elevation of Neuregulin-ErbB signalling activity and transit enhanced cardiomyocytes proliferation. (A) Left panel, in situ hybridization for nrg1 on ventricle sections from 18 days old control and Zfpm1 mutant animals. Right panel, qPCR experiments confirmed up-regulation of nrg1 in endocardial cell. Error bars represent mean ± SEM. ** p < 0.01. (B) Left panel, representative Western blot demonstrating elevated phosphor-MAPK and phosphor-AKT level in hearts of Zfpm1 mutant animals. Tubulin and total AKT were used as loading control. Left panel, quantification of phosphor-MAPK and phosphor-AKT proteins normalized by either Tublin or total AKT. Error bars represent mean ± SEM. * p < 0.05. (C) In situ hybridization for Neuregulin-ErbB signalling target genes on ventricle sections from 18 days old control and Zfpm1 mutant animals. (D) Ventricles from 18 days old control and Zfpm1 mutant animals stained for BrdU incorporation (red) to assess cardiomyocyte proliferation. Middle panels, high-magnification images of the boxed areas in the left panels. Arrowheads indicated the proliferating cardiomyocytes. Scale bar: 50 µm. Right panel, quantification of BrdU-positive nuclei in Zfpm1^-/- ventricle, data are mean ± s.e.m. Tg(myh7: GFP) transgene was introduced to identify cardiomyocyte. 8 sections from 4 control and 8 sections from 3 Zfpm1^-/-fish were examined. ** p < 0.01. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)