Adenoviral gene transfer of activated phosphatidylinositol 3′-kinase and Akt inhibits apoptosis of hypoxic cardiomyocytes in vitro

T Matsui, L Li, F del Monte, Y Fukui, TF Franke… - Circulation, 1999 - Am Heart Assoc
T Matsui, L Li, F del Monte, Y Fukui, TF Franke, RJ Hajjar, A Rosenzweig
Circulation, 1999Am Heart Assoc
Background—The intracellular signaling pathways that control cardiomyocyte apoptosis
have not been fully defined. Because insulin-like growth factor-1 (IGF-1) prevents
cardiomyocyte apoptosis, we examined the role of its downstream signaling molecules in an
in vitro model of hypoxia-induced cardiomyocyte apoptosis. Methods and Results—
Treatment of rat neonatal cardiomyocytes with IGF-1 increased activity of both
phosphatidylinositol 3′(PI 3)-kinase and its downstream target, Akt (also known as protein …
Background—The intracellular signaling pathways that control cardiomyocyte apoptosis have not been fully defined. Because insulin-like growth factor-1 (IGF-1) prevents cardiomyocyte apoptosis, we examined the role of its downstream signaling molecules in an in vitro model of hypoxia-induced cardiomyocyte apoptosis.
Methods and Results—Treatment of rat neonatal cardiomyocytes with IGF-1 increased activity of both phosphatidylinositol 3′ (PI 3)-kinase and its downstream target, Akt (also known as protein kinase B or PKB). Cardiomyocytes were subjected to hypoxia for 24 hours, and apoptosis was assessed by DNA laddering, TUNEL staining, and ELISA for histone-associated DNA fragments. IGF-1 treatment (100 nmol/L) reduced cardiomyocyte apoptosis, and this effect was inhibited by simultaneous treatment with a PI 3-kinase inhibitor. Cardiomyocytes were infected with either a control adenovirus (Ad.EGFP) or adenoviruses carrying constitutively active forms of PI 3-kinase (Ad.BD110) or Akt (Ad.myr-Akt-HA). Ad.BD110 significantly inhibited apoptosis of hypoxic cardiomyocytes compared with Ad.EGFP (61.0±4.6% less DNA fragmentation than in Ad.EGFP-infected cells, P<0.0001). Ad.myr-Akt-HA even more dramatically inhibited apoptosis of hypoxic cardiomyocytes (90.9±1.4% less DNA fragmentation than in controls, P<0.0001).
Conclusions—IGF-1 activates PI 3-kinase and Akt in cardiomyocytes. Activated PI 3-kinase and Akt are each sufficient to protect hypoxic cardiomyocytes against apoptosis in vitro. Adenoviral gene transfer provides a useful tool for investigating the role of these signaling pathways in cardiomyocyte apoptosis.
Am Heart Assoc