title: Proteolytic gene expression differs at rest and after resistance exercise between young and old women.
abstract: BACKGROUND
  Skeletal muscle atrophy in rodents is associated with increased gene expression of proteolytic markers muscle-RING-finger protein 1 (MuRF-1) and atrogin-1. In humans with age-related muscle atrophy, known as sarcopenia, little is known about these key proteolytic biomarkers. Therefore, the purpose of this investigation was 2-fold: (i) measure messenger RNA (mRNA) expression of proteolytic genes MuRF-1, atrogin-1, forkhead box (FOXO)3A, and tumor necrosis factor-alpha (TNF-alpha) in young and old women at rest, and (ii) measure these proteolytic genes in response to an acute resistance exercise (RE) bout, a known hypertrophic stimulus.
  
  
  METHODS
  A group of old women (OW: n =6, 85+/-1 years, thigh muscle =89+/-4 cm(2)) and young women (YW: n=8, 23+/-2 years, thigh muscle = 122+/-6 cm(2)) performed three sets of 10 knee extensions at 70% of one-repetition maximum. Muscle biopsies were taken from the vastus lateralis before and 4 hours after RE. Using real-time reverse transcription-polymerase chain reaction (RT-PCR), mRNA was amplified and normalized to GAPDH.
  
  
  RESULTS
  At rest, OW expressed higher mRNA levels of MuRF-1 (p=.04) and FOXO3A (p=.001) compared to YW. In response to RE, there was an age effect (p=.01) in the induction of atrogin-1 (OW: 2.5-fold). Both YW and OW had an induction (p=.001) in MuRF-1 (YW: 3.6-fold; OW: 2.6-fold) with RE.
  
  
  CONCLUSIONS
  These data show that the regulation of ubiquitin proteasome-related genes involved with muscle atrophy are altered in very old women (>80 years). This finding is manifested both at rest and in response to RE, which may contribute to the large degree of muscle loss with age.
authors.affiliation: Human Performance Laboratory, Ball State University, Muncie, Indiana 47306, USA.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Raue
authors.forename: Dustin
authors.initials: D
authors.lastname: Slivka
authors.forename: Bozena
authors.initials: B
authors.lastname: Jemiolo
authors.forename: Chris
authors.initials: C
authors.lastname: Hollon
authors.forename: Scott
authors.initials: S
authors.lastname: Trappe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D015444:Exercise; D005260:Female; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000235:genetics; D006801:Humans; D009124:Muscle Proteins / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000032:analysis; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics; D000070584:Tripartite Motif Proteins; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics
chemical_list: C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D009124:Muscle Proteins; D012333:RNA, Messenger; D000070584:Tripartite Motif Proteins; D014409:Tumor Necrosis Factor-alpha; C440907:FBXO32 protein, human; D044843:SKP Cullin F-Box Protein Ligases; C440908:TRIM63 protein, human; D044767:Ubiquitin-Protein Ligases