P1 pups were injected subcutaneously with AAV9.GFP or AAV9.VGLL4-GFP. Control (Ctrl) mice were untreated. Hearts were analyzed at P8.
(A) AAV9 expression constructs. AAV9.GFP and AAV9.VGLL4-GFP incorporate the cardiac troponin T (cTNT) promoter to drive selective CM expression. Heart protein immunoblots probed with GFP antibody demonstrated VGLL4-GFP fusion protein expression (asterisk).
(B) Echocardiographic assessment of neonatal heart function. FS%, fractional shortening. n = 4.
(C) Whole-mount images of hearts showing lack of substantial differences between groups. Scale bar, 2 mm.
(D) Heart to body weight ratio was not significantly different (NS) between groups. n = 3.
(E) Representative pH3 staining results. Scale bar, 50 μm.
(F) Quantitation of pH3+ CMs. n = 3. NS, not significant.
(G) Cell-cycle gene expression from P8 ventricular myocardium after treatment with AAV9.GFP or AAV9.VGLL4-GFP. Gene expression was measured by qRT-PCR and normalized to the AAV9.GFP group. n = 4. NS, not significant.
All error bars represent the SEM.