Recent data suggest that the cardiac-restricted transcription factor GATA-4 is an anti-apoptotic factor required for adaptive responses as well as a key regulator of hypertrophy and hypertrophy-associated genes in the heart. As a leading cause of chronic heart failure, reversal of post-infarction left ventricular remodeling represents an important target for therapeutic interventions. Here we studied the role of GATA-4 as a mediator of post-infarction remodeling. Rats were subjected to experimental myocardial infarction (MI) by ligating the left anterior descending coronary artery (LAD). Ligation of the LAD decreased the DNA binding activity of GATA-4 by 69 % at day 1 after MI (P<0.001, n=7– 8) as assessed by gel mobility shift assays. At 2 weeks the GATA-4 DNA binding was significantly upregulated (2.4-fold, P<0.05, n=7), and returned to baseline at 4 weeks. To determine the functional role of GATA-4, rats underwent LAD ligation followed by peri-infarct intramyocardial delivery of adenoviral vector expressing GATA-4. Hearts treated with the GATA-4 gene transfer exhibited significantly increased ejection fraction (58±5% vs. 38±3% in LacZ-treated control animals with MI, P<0.001, n=8 –9) and fractional shortening (28±3% vs. 16±1%, P<0.001, n=8 –9) 2 weeks after MI. Accordingly, the infarct size was significantly reduced (26±4% vs. 45±4%, P<0.01, n=8 –9). To determine the cardioprotective mechanisms of GATA-4, the number of cardiac stem cells, apoptotic cardiomyocytes and capillaries were assessed. The number of capillaries (59±4/field vs. 48±3/field, P<0.051, n=7– 8) and c-kit positive stem cells (13±5 cells vs. 4±2 cells, P<0.05, n=7– 8) were increased in GATA-4 treated hearts, and a tendency to decreased apoptosis was observed in TUNEL-stained histological sections. These results indicate that the reversal of reduced GATA-4 activity prevents adverse post-infarction remodeling through increased angiogenesis, recruitment of cardiac stem cells and anti-apoptosis. GATA-4-based gene transfer may represent a novel, efficient therapeutic approach for heart failure.
Pathophysiologic role of myocardial apoptosis in post-infarction left ventricular remodeling
