Figure 6. Generation of cardiac-specific DUSP8 transgenic mice and phenotypic characterization.

A, Schematic of the bi-transgenic inducible expression system used to regulate DUSP8 heart-specific overexpression. Abbreviations: tetO, tetracycline operator with response elements. B and C, Analysis of cardiac DUSP8 expression by real-time PCR in double transgenic mice (DTG) versus only single transgenic tTA mice (B) and Western blot (C) from hearts of mice 6 weeks after Dox removal to induce expression, 9 weeks-old in total. *p<0.05 vs tTA. Dusp8 KO heart samples are shown as a control. D, Western blot analysis for MAPK phosphorylation and total MAPKs in tTA controls and DTG mice at 9 weeks of age. At least six separate heart samples were analyzed for each group with similar results. E and F, Echocardiographic assessment of FS and LV internal chamber dimension at end diastole (LVIDd) in tTA controls and DTG mice at 9 weeks of age with 6 weeks of transgene induction. *p<0.05 vs tTA control. Number of mice analyzed is shown in the bars. G, HW/BW ratio in tTA controls and DTG mice at 9 weeks of age. *p<0.05 vs tTA. Number of mice analyzed is shown in the bars. H, Analysis of length/width ratio of adult cardiac myocytes isolated from hearts of tTA and DTG mice with 6 weeks of transgene induction. A total of 170 myocytes were analyzed for each group. *p<0.05 vs tTA. I, Real-time PCR analysis of mRNA for the indicated genes from the hearts of tTA control and DTG mice. N=4 hearts for each group. *p<0.05 vs tTA. J, Masson trichrome-stained histological sections of hearts from tTA and DTG mice at 9 weeks of age. Magnification is 40X total. K, Western blot analysis for MAPK phosphorylation and total MAPK levels from hearts of tTA controls and DTG mice after TAC stimulation for the indicated time in minutes. The 0 time point represents sham mice. At least 4 separate samples were analyzed.