Abstract Body: Introduction: Phosphorylation of GRK2 (G-protein-coupled receptor kinase 2) at serine-670 (phospho-S670-GRK2) causes mitochondrial dysfunction and cardiomyocyte degeneration under conditions of ischemia.
Research Question: We asked whether targeting of phospho-S670-GRK2 could improve symptoms of heart failure and other age-related pathologies with mitochondrial dysfunction.
Aims: We aimed to target mitochondrial phospho-S670-GRK2 by treatment with CPD10 (1-(1,3-benzodioxol-5-yl)-4-(cyclopropanecarbonyl)-3-hydroxy-2-phenyl-2H-pyrrol-5-one), which inhibits phospho-S670-GRK2 while preserving the non-phosphorylated GRK2.
Methods: As a model of cardiac dysfunction, we used 6-month-old, non-transgenic B6 mice with heart failure, induced by chronic pressure overload caused by three months of abdominal aortic constriction (AAC). Oral treatment with CPD10 (3 mg/kg/d in drinking water) was initiated one month after AAC-induced heart failure and continued for 2 months. Cardiac function was determined by transthoracic echocardiography in M-mode. Sperm vitality was assessed in aged, 18-month-old B6 mice with CPD10 treatment initiated at an age of 3 months.
Results: Treatment with CPD10 significantly improved the cardiac function of mice with AAC-induced heart failure. The left ventricular ejection fraction (LVEF) of CPD10-treated mice was 42.8 ±. 2.7 % compared to 28.2 ± 3.0 % of untreated mice (± s.d.; n=6; p<0.0001; unpaired, two-tailed t-test). The improved cardiac function was accompanied by reduced cardiac dilation with a left ventricular internal diameter in diastole (LVIDd) of 5.5 ± 0.2 mm in CPD10-treated mice and 6.6 ± 0.5 mm in untreated mice (± s.d.; n=6; p=0.0012; unpaired, two-tailed t-test). Aging was visibly retarded, with less grey coloring of the black fur of treated B6 mice. The anti-aging activity of CPD10 was further demonstrated by an improved sperm vitality as a well-established indicator of aging. The total sperm motility was 57.9 ± 5.3 % in CPD10-treated, aged B6 mice and 18.3 ± 8.6 % in untreated, 18-month-old B6 controls (mean ± s.d.; n=6; p<0.0001; unpaired, two-tailed t-test).
Conclusion: Targeting of mitochondrial phospho-S670-GRK2 with CPD10 improves AAC-induced cardiac dysfunction and retards aging.