The activation of cardiac dSir2-related pathways mediates physical exercise resistance to heart aging in old Drosophila

Cardiac aging is majorly characterized by increased diastolic dysfunction, lipid accumulation, oxidative stress, and contractility debility. The Sir2/Sirt1 gene overexpression delays cell aging and reduces obesity and oxidative stress. Exercise improves heart function and delays heart aging. However, it remains unclear whether exercise delaying heart aging is related to cardiac Sir2/Sirt1-related pathways. In this study, cardiac dSir2 overexpression or knockdown was regulated using the UAS/hand-Gal4 system in Drosophila. Flies underwent exercise interventions from 4 weeks to 5 weeks old. Results showed that either cardiac dSir2 overexpression or exercise remarkably increased the cardiac period, systolic interval, diastolic interval, fractional shortening, SOD activity, dSIR2 protein, Foxo, dSir2, Nmnat, and bmm expression levels in the aging flies; they also notably reduced the cardiac triacylglycerol level, malonaldehyde level, and the diastolic dysfunction index. Either cardiac dSir2 knockdown or aging had almost opposite effects on the heart as those of cardiac dSir2 overexpression. Therefore, we claim that cardiac dSir2 overexpression or knockdown delayed or promoted heart aging by reducing or increasing age-related oxidative stress, lipid accumulation, diastolic dysfunction, and contractility debility. The activation of cardiac dSir2/Foxo/SOD and dSir2/Foxo/bmm pathways may be two important molecular mechanisms through which exercise works against heart aging in Drosophila.