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REDD1 reduces the responsiveness of mTORC1 after resistance exercise and amino acid intake in skeletal muscle of elderly people (702.4)
Author(s) -
Francaux Marc,
Demeulder Bénédicte,
Naslain Damien,
Fortin Raphaël,
Lutz Olivier,
Caty Gilles
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.702.4
Subject(s) - anabolism , mtorc1 , leg press , medicine , sarcopenia , phosphorylation , ageing , endocrinology , p70 s6 kinase 1 , muscle biopsy , resistance training , biopsy , protein kinase b , chemistry , biochemistry
The aim of the present experiment was to highlight the difference in mTORC1 regulation between young and elderly people after exercise and amino acid intake. Eight younger (23±1 y) and 8 older (70±7 y) healthy volunteers were recruited. After an overnight fast, a first biopsy sample was taken in the vastus lateralis muscle. Then, the subjects performed a one‐leg resistance exercise consisting in 10 sets of 10 leg extensions at 70% of their 3‐RM (repetition‐maximum) previously measured. Immediately after the exercise completion, the subjects drank a beverage containing 30 g of whey protein hydrolyzate whose 2.5 g was leucine. Thirty minutes after the beverage intake, a second biopsy was taken in the exercised leg and a third one in the contralateral leg. In both groups, feeding increased the S6K1 phosphorylation and resistance exercise potentiated this effect. However, the range of these increases was about the half in elderly as compared to the young subjects confirming a reduced responsiveness of mTORC1 in elderly people. Feeding doubled the phosphorylation of PKB (Ser473) in both groups. Resistance exercise reinforced this effect in young but not in elderly people. The expression of REDD1 was systematically higher in elderly people. REDD1 was slightly and not significantly increased by exercise in young subjects whereas it was doubled in elderly suggesting that REDD1 is probably a major actor for the development of anabolic resistance during ageing. The phosphorylation state of PRAS40 (Thr246) increased after feeding but similarly in both groups. The phosphorylation state of AMPK (Thr172) was affected neither by feeding nor by exercise. All together, these results indicate that mTORC1 acts as a molecular integrator receiving positive and negative signals from its upstream regulators. The reduced responsiveness to anabolic stimuli observed in elderly people seems related to a higher REDD1 expression combined with a lower exercise‐induced activation of PKB. Grant Funding Source : Supported by the Walloon Region (Plan Marshall – Wagralim ‐ Geramino)