Bedrest increases burden of mitochondrial DNA deletions in human muscle (956.1)

Abstract

We explored whether muscle disuse (i.e. bed rest) contributes to mitochondrial (mt)DNA deletions in skeletal muscle. mtDNA deletions have been associated with various degenerative processes (e.g. sarcopenia) and sedentary behavior. Human muscle tissue from a small sample (n=3) taken before and after a 28‐day bed rest were subjected to mutational analysis using, a restriction digestion / long range digital PCR approach. Total DNA was digested with SnaBI, an enzyme with a single restriction site located in an area commonly removed in deleted mtDNA molecules. DNA was exposed to long‐range PCR capable of amplifying most of the mitochondrial genome. Restriction digestion rendered mtDNA un‐amplifiable, except for molecules with deletions. The actual number of molecules with deletions and types thereof were determined using highly diluted DNA samples, reaching single molecule per reaction, in multiple independent PCR reactions, so that molecules could be directly counted (“digital PCR”). We found an increase in the fraction of molecules with mtDNA deletions after bedrest, relative to intact wild type molecules. This finding suggests that disuse results in skeletal muscle mtDNA deletions. Further studies are needed to determine the association of these deletions with physiological and metabolic changes seen with disuse or sedentary behavior.Grant Funding Source: Supported by Ellison Medical Foundation, NSBRI‐NPFR00301, GCRC M01 RR00