Endurance Training Regulates Skeletal Muscle UPRmt Response To Acute Exercise Through Epigenetic Modification

Objective:Mitochondria are important organelles of eukaryotic cells.Changes in metabolism or environmental changes can lead to the accumulation of unfolded and misfolded proteins in mitochondria,thereby initiating the mitochondrial unfolded protein response（UPRmt）.Activation of UPRmt enhances mitochondrial protein homeostasis,protects mitochondria from further damage,and promotes recovery and regeneration of defective mitochondria.Studies have shown that epigenetic modifications play an important role in mitochondrial UPRmt.Histone lysine demethylases JMJD3 and PHF8 are positively correlated with the methylation status m RNA and protein expression of UPRmt-related genes in mammals.In present study,We used the acute exercise model to obervese the change of ROS,AMPK,UPRmt-related gene histone epigenetic modification of skeletal muscle in rats during and the post-acute exercise（time courses）,before and after endurance training respectively,to exploer the role of epigenetic modification on activition of UPRmt,Furtherly,to suggest the possible mechanism of exercise-induced epigenetic modification in the regulation of UPRmt in skeletal muscle by compared the differences of the above cellular events in response to an acute exercise before and after endurance training.Methods:A bout of acute incremental exercise model in rats was established in the control group and the endurance training group to explore the regulation of epigenetic modification on skeletal muscle UPRmt during acute exercise.The AMR probe method was used to measure H₂O₂,reflecting the level of mitochondrial ROS generation;Western blotting was used to determine the protein expression levels of p-AMPK/AMPK,demethylase JMJD3 and PHF8;chromatin immunoprecipitation（Ch IP）was used to determine the UPRmt-related genes c-Jun,CHOP,HSP60,CLp P promoter region H3K27me3 levels.SPSS Statistics 21 was used for data analysis.Results:1.Before endurance training,in acute incremental load exercise,the rate of ROS generation was significantly increased at 150 min of exercise;the enrichment level of H3K27me3 in the CHOP promoter region was significantly decreased at 12 hours of rest after exercise;the enrichment of H3K27me3 in the HSP60 promoter region The level of H3K27me3 in the CLp P promoter region was significantly decreased at150min exercise;the enrichment level of H3K27me3 in CLp P promoter region was significantly increased at 150min exercise;JMJD3 protein expression level was significantly increased at 150min exercise;PHF8 protein expression level was significantly increased at 150min exercise.2.After endurance training,in acute incremental load exercise,the rate of ROS generation was significantly increased at 90 minutes of exercise;the enrichment level of H3K27me3 in the c-Jun promoter region was significantly decreased at 150minutes of exercise and 12 hours of rest after exercise;HSP60 promoter The enrichment level of H3K27me3 in the region decreased significantly at 150min of exercise;the enrichment level of H3K27me3 in the CLp P promoter region was significantly decreased at 150min of exercise and 12h of rest after exercise;the expression level of p-AMPK protein was significantly increased at 150min of exercise;JMJD3 protein The expression level was significantly increased at 150min of exercise;the expression level of PHF8 protein was significantly increased at 150min of exercise.3.Compared with before endurance training,the rate of ROS generation after endurance training was significantly reduced at rest and at 150min of exercise;p-AMPK protein level was significantly increased at 150min of exercise after endurance training;JMJD3 and PHF8 were significantly increased at 150min of exercise after endurance training significantly increased;the enrichment level of H3K27me3 in the promoter region of CHOP,HSP60 and CLp P was significantly decreased at 150 min of exercise.Conclusions:1.During acute increasing load exercise,exercise-derived ROS may activate AMPK,thereby up-regulating the expression of histone demethylases JMJD3 and PHF8,and reducing the enrichment level of UPRmt-related genes histone methylation modification H3K27me3,thereby promoting UPRmt-related genes.Gene transcription and protein expression.2.The enrichment level of H3K27me3 in the promoter region of UPRmt-related genes decreased after endurance training,which made UPRmt more easily activated,which may be one of the mechanisms of endurance training to induce apparent memory and improve exercise response.