The putative leucine sensor Sestrin2 is hyperphosphorylated by acute resistance exercise but not protein ingestion in human skeletal muscle
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Dietary protein and resistance exercise (RE) are both potent stimuli of the mammalian target of rapamycin complex 1 (mTORC1). Sestrins1, 2, 3 are multifunctional proteins that regulate mTORC1, stimulate autophagy and alleviate oxidative stress. Of this family, Sestrin2 is a putative leucine sensor implicated in mTORC1 and AMP-dependent protein kinase (AMPK) regulation. There is currently no data examining the responsiveness of Sestrin2 to dietary protein ingestion, with or without RE.
In Study 1, 16 males ingested either 10 or 20 g of milk protein concentrate (MPC) with muscle biopsies collected pre, 90 and 210 min post-beverage consumption. In Study 2, 20 males performed a bout of RE immediately followed by the consumption of 9 g of MPC or carbohydrate placebo. Analysis of Sestrins, AMPK and antioxidant responses was examined.
Dietary protein ingestion did not result in Sestrin2 mobility shift. After RE, Sestrin2 phosphorylation state was significantly altered and was not further modified by post-exercise protein or carbohydrate ingestion. With RE, AMPK phosphorylation remained stable, while the mRNA expressions of several antioxidants were upregulated.
Dietary protein ingestion did not affect the signalling by the family of Sestrins. With RE, Sestrin2 was hyperphosphorylated, with no further evidence of a relationship to AMPK signalling.
KeywordsAmino acid Resistance exercise Mammalian target of rapamycin Oxidative stress Antioxidant Sestrins Hyperphosphorylation
- 4E BP1
Eukaryotic initiation factor 4E-binding protein 1
AMP-activated protein kinase
Analysis of variance
GTPase-activating protein activity towards Rags
Human embryonic kidney cells 293
Heme oxygenase 1
Kelch-like ECH-associated protein
Milk protein concentrate
Muscle protein synthesis
Mammalian target of rapamycin complex 1
Nuclear factor (erythroid-derived 2)-like 2
Ribosomal protein S6 kinase 1
Reactive oxygen species
Ribosomal protein S6
Standard error of mean
The study was funded by AgResearch (through Strategic Science Investment Fund contracts A19079 and A21246). MPGB is a current employee of AgResearch.
NZ, CJM and DCS designed the study; NZ and RFD conducted experiments; NZ, BS and TLM analysed data; NZ, CJM and DCS drafted manuscript; NZ, RFD, MPGB, BS, TLM, CJM and DCS critically evaluated and contributed to the manuscript.
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