Omi/HtrA2 is known to be a pro-apoptotic protein and also participates in the regulation of autophagy.Previous studies have found that centrifugal exercise can induce an increase in Omi/HtrA2 protein expression in damaged skeletal muscle cells.Omi/HtrA2-Hax1-Beclin1,as the newly discovered autophagy signaling pathway in cells since 2010, has not been reported whether can be specifically expressed in injured skeletal muscle. PURPOSE: This study was designed to explore the role of Omi/HtrA2 during autophagy in skeletal muscle induced by centrifugal exercise injury. METHODS: 168 SD rats were randomly divided into control group (C), dummy control group (D), ucf-101 group (U), exercise group (E) and exercise+ucf-101 group (EU).The U group was injected with ucf-101, a specific inhibitor of Omi/HtrA2;D injection of equal amount of normal saline;for group E with acute heavy load treadmill exercise, the slope was -16°, the speed was 16m/min, and the continuous exercise was 90 min;the EU group performed the same exercise after injection of ucf-101.Soleus muscle was taken from the rats at 0h, 12h, 24h, 48h and 72h after intervention.Ultrastructural changes of autophagosomes in soleus muscle cells were observed by TEM;the expressions of Omi/HtrA2, hax-1 and Beclin1 were detected by Western Blot;the position and content of LC3 were observed by immunofluorescence technique;The binding levels of Hax-1 and Beclin1 were determined by immunoprecipitation. RESULTS:The expression of Omi/HtrA2 protein was increased in group E(0h,2.056±0.114,P<0.05), and the binding of Hax-1 and Beclin1 protein was weakened(0h,0.805±0.095,P<0.05).The expression of Omi/HtrA2 protein was decreased in the U group (0h,0.406±0.178,P<0.01), and the binding of Hax-1 and Beclin1 protein was enhanced (0h,1.536±0.051,P<0.05;24h,8.000±0.197,P<0.01).Compared with group E, autophagy in EU group was decreased, Beclin1 expression was inhibited, and LC3 fluorescence intensity was decreased(Beclin1,U0=0.718±0.039,E0=1.870±0.291,EU0=0.871±0.096). CONCLUSION: A high-load centrifugal exercise can induce autophagy in skeletal muscle, which may enhance the cutting effect of Omi/HtrA2 on Hax-1 through exercise, reduce the binding inhibition level of the latter on Beclin1, and finally enhance autophagy.
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