Figure 3. Nrg1 reactivation without injury induces proliferation of ventricular wall cardiomyocytes.
(A and B) Section images from uninjured cmlc2:CreER; β-act2:BSNrg1 and control ventricles at 7 days post-tamoxifen treatment (dpt), stained for Mef2+PCNA+ cells. Insets show high-zoom views of the boxed regions, and arrowheads indicate Mef2+PCNA+ nuclei. Dashed lines delineate cortical (wall) from trabecular muscle. Scale bars represent 100 µm. (C) Quantification of cardiomyocyte proliferation in cmlc2:CreER; β-act2:BSNrg1 and controls in the trabecular muscle compartment at 7 (n = 8, 9) and 14 dpt (n = 10, 10). Data are represented as mean ± SEM. *p < 0.05, Mann–Whitney Ranked Sum Test. (D) Quantification of cardiomyocyte proliferation in cortical muscle at 7 (n = 8, 9) and 14 dpt (n = 10, 10), from groups in (A and B). Data are represented as mean ± SEM. *p < 0.05, Mann–Whitney Ranked Sum Test. (E) Quantification of total cardiomyocyte proliferation at 7 (n = 8, 9) and 14 dpt (n = 10, 10), from groups in (C and D). Data are represented as mean ± SEM. *p < 0.05, Mann–Whitney Ranked Sum Test.