Figure 6

Phenotype of neonatal mice following the deletion of Nkx2.5 + cardiomyoblasts. (A) Breeding and doxycycline treatment strategy for Cre/LoxP-mediated ablation of neonatal Nkx2.5 + cardiomyoblasts. The excision of the stopper cassette results in diphtheria toxin A (DTA) expression in Cre-expressing cells. (B) The hypertrophic response of neonatal mouse hearts that have undergone ablation of their Nkx2.5 + cardiomyoblasts shortly after birth. The body weight (left panel), heart weight (middle panel), and the ratio of heart weight to body weight (right panel) are shown (n = 4 for each time point). (C) Histological examination of hearts in mice with deficiency of Nkx2.5 + cardiomyoblasts. At 9 weeks old, the cardiomyoblast-deficient hearts (Cre + /DTA + ) are larger in size than that of their littermate control (Cre-/DTA+ ) (right panel).