Exercise training and dietary restriction affect PINK1/Parkin and Bnip3/Nix-mediated cardiac mitophagy in mice

The aim of this study was to investigate the effects of exercise training and dietary restriction on cardiac PINK1/Parkin and Bnip3/Nix pathways involved in mitophagy. C57BL/6 mice were assigned to control (C), exercise training (T), dietary restriction (D) and exercise training + dietary restriction (TD) groups. T group undertook 10 weeks of swimming training. D group was subjected to 40% food reduction. TD group undertook the combination of exercise training and food reduction. Suspectable mitophagy autophagosomes can be observed in T and D groups and more autophagosomes appeared in TD group. In T group, both PINK1 mRNA and protein levels increased significantly (p < 0.01) but Bnip3 and Nix expressions decreased significantly (p < 0.05). Dietary restriction resulted in elevation of Drp1 (p < 0.01) and reduction and Nix (p < 0.05) in D group. The load in TD group resulted in serious mitochondrial abnormalities and myofibrillar damages accompanied by increases in PINK1 and Drp1 levels (p < 0.01) and decreases in Bnip3 and Nix levels (p < 0.05). The increase in PINK1 expression (exercise protocol) or Drp1 expression (diet protocol) contributes to cardiac activation of mitophagy, whereas Bnip3 and Nix are not implicated in this activation.