Effects of age and unaccustomed resistance exercise on mitochondrial transcript and protein abundance in skeletal muscle of men.
Mitochondrial dysfunction may contribute to age-associated muscle atrophy. Previous data has shown that resistance exercise (RE) increases mitochondrial gene expression and enzyme activity in older adults; however, the acute response to RE has not been well characterized. To characterize the acute mitochondrial response to unaccustomed RE, healthy young (21 ± 3 yr) and older (70 ± 4 yr) men performed a unilateral RE bout for the knee extensors. Muscle biopsies were taken at rest and 3, 24, and 48 h following leg press and knee extension exercise. The expression of the mitochondrial transcriptional regulator proliferator-activated receptor γ coactivator 1-α (PGC-1α) mRNA was increased at 3 h postexercise; however, all other mitochondrial variables decreased over the postexercise period, irrespective of age. ND1, ND4, and citrate synthase (CS) mRNA were all lower at 48 h postexercise, along with specific protein subunits of complex II, III, IV, and ATP synthase. Mitochondrial DNA (mtDNA) copy number decreased by 48 h postexercise, and mtDNA deletions were higher in the older adults and remained unaffected by acute exercise. Elevated mitophagy could not explain the reduction in mitochondrial proteins and DNA, because there was no increase in ubiquitinated voltage-dependent anion channel (VDAC) or its association with PTEN-induced putative kinase 1 (Pink1) or Parkin, and elevated p62 content indicated an impairment or reduction in autophagocytic flux. In conclusion, age did not influence the response of specific mitochondrial transcripts, proteins, and DNA to a bout of RE.
['Ogborn|Daniel I|DI|', 'McKay|Bryon R|BR|', 'Crane|Justin D|JD|', 'Safdar|Adeel|A|', 'Akhtar|Mahmood|M|', 'Parise|Gianni|G|', 'Tarnopolsky|Mark A|MA|']
D000293:Adolescent D000367:Age Factors D000368:Aged D000375:Aging D001343:Autophagy D001706:Biopsy D004272:DNA, Mitochondrial D005786:Gene Expression Regulation D006801:Humans D008297:Male D008931:Mitochondria, Muscle D024101:Mitochondrial Proteins D018482:Muscle, Skeletal D012333:RNA, Messenger D055070:Resistance Training D013997:Time Factors D014158:Transcription, Genetic D055815:Young Adult
resistance exercise skeletal muscle autophagy mitochondria