title: Exercise-induced activation of STAT3 signaling is increased with age.
abstract: Activation of the transcription factor signal transducers and activators of transcription (STAT) 3 is common to many inflammatory cytokines and growth factors, with recent evidence of involvement in skeletal muscle regeneration. The purpose of this study was to determine whether STAT3 signaling activation is regulated differentially, at rest and following intense resistance exercise, in aged human skeletal muscle. Skeletal muscle biopsies were harvested from healthy younger (n = 11, 20.4 +/- 0.8 years) and older men (n = 10, 67.4 +/- 1.3 years) under resting conditions and 2 h after the completion of resistance exercise. No differences were evident at rest, whereas the phosphorylation of STAT3 was significantly increased in old (23-fold) compared to young (5-fold) subjects after exercise. This correlated with significantly higher induction of the STAT3 target genes including; interleukin-6 (IL-6), JUNB, c-MYC, and suppressor of cytokine signaling (SOCS) 3 mRNA in older subjects following exercise. Despite increased SOCS3 mRNA, cellular protein abundance was suppressed. SOCS3 protein is an important negative regulator of STAT3 activation and cytokine signaling. Thus, in aged human muscle, elevated responsiveness of the STAT3 signaling pathway and suppressed SOCS3 protein are evident following resistance exercise. These data suggest that enhanced STAT3 signaling responsiveness to proinflammatory factors may impact on mechanisms of muscle repair and regeneration.
authors: School of Exercise and Nutrition Science, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia.
authors: Marissa K
authors: MK
authors: Trenerry
authors: Kate A
authors: KA
authors: Carey
authors: Alister C
authors: AC
authors: Ward
authors: Michelle M
authors: MM
authors: Farnfield
authors: David
authors: D
authors: Cameron-Smith
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000378:metabolism / Q000502:physiology; D010766:Phosphorylation; D010807:Physical Endurance / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D012038:Regeneration / Q000235:genetics; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology
chemical_list: D018836:Inflammation Mediators; D012333:RNA, Messenger; C106644:SOCS3 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins