Parker, L., Caldow, M. K, Watts, R., Levinger, P., Cameron-Smith, D. & Levinger, I. (2017). Age and sex differences in human skeletal muscle fibrosis markers and transforming growth factor-ß signaling. European Journal of Applied Physiology,117(7), H. Westerblad, K. R. Westerterp. 1463-1472. Germany: Springer Verlag. Retrieved from https://doi.org/10.1007/s00421-017-3639-4
Purpose The aim of the study was to determine whether higher fibrosis markers in skeletal muscle of older adults are accompanied by increased expression of components of the canonical TGF-β signal transduction pathway. Methods Fourteen healthy young (21–35 years; 9 males and 5 females) and seventeen older (55–75 years; 9 males and 8 females) participants underwent vastus lateralis biopsies to determine intramuscular mRNA and protein expression of fibrogenic markers and TGF-β signaling molecules related to TGF-β1 and myostatin. Results Expression of mRNA encoding the pro-fibrotic factors; axin 2, collagen III, β-catenin and fibronectin, were all significantly higher (all p < 0.05) in the older participants (350, 170, 298, and 641%, respectively). Furthermore, axin 2 and β-catenin mRNA were significantly higher in older females than older males (p < 0.05). Gene expression of ActRIIB, myostatin, and TGF-β1 were higher in older adults compared to younger adults (all p < 0.05). There was, however, no difference in the total protein content of myostatin, myoD or myogenin (all p > 0.05), whereas Smad3 protein phosphorylation was 48% lower (p < 0.05) in muscle from older adults. Conclusions Increased abundance of mRNA of fibrotic markers was observed in muscle from older adults and was partly accompanied by altered abundance of pro-fibrotic ligands in a sex specific manner.
Mary MacKillop Institute for Health Research
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