Assessing the mechanistic target of rapamycin complex-1 pathway in response to resistance exercise and feeding in human skeletal muscle by multiplex assay

The mechanistic target of rapamycin complex-1 (mTORC-1) is a key nutrient and contraction-sensitive protein that regulates a pathway leading to skeletal muscle growth. Utilizing a multiplex assay, we aimed to examine the phosphorylation status of key mTORC-1-related signalling molecules in response to protein feeding and resistance exercise. Eight healthy men (age, 22.5 ± 3.1 years; mass, 80 ± 9 kg; 1-repetition maximum leg extension, 87 ± 5 kg) performed 4 sets of unilateral leg extensions until volitional failure. Immediately following the final set, all participants consumed a protein-enriched beverage. A single skeletal muscle biopsy was obtained from the vastus lateralis before (Pre) with further bilateral biopsies at 1 h (1 h exercised legs (FEDEX) and 1 h nonexercised legs (FED)) and 3 h (3 h FEDEX and 3 h FED) after drink ingestion. Phosphorylated AktSer473 was significantly elevated from Pre at 1 h FEDEX. Phosphorylated p70S6K1Thr412 was significantly increased above Pre at 1 h FEDEX and 1 h FED and was still significantly elevated at 3 h FEDEX but not 3 h FED. Phosphorylated rpS6Ser235/236 was also significantly increased above Pre at 1 h FEDEX and 1 h FED with 1 h FEDEX greater than 1 h FED. Our data highlight the utility of a multiplex assay to assess anabolic signalling molecules in response to protein feeding and resistance exercise in humans. Importantly, these changes are comparable with those as previously reported using standard immunoblotting and protein activity assays.

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Resistance exercise initiates mechanistic target of rapamycin (mTOR) translocation and protein complex co-localisation in human skeletal muscle

Scientific Reports ◽

10.1038/s41598-017-05483-x ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 39

Author(s):

Zhe Song ◽

Daniel R. Moore ◽

Nathan Hodson ◽

Carl Ward ◽

Jessica R. Dent ◽

...

Keyword(s):

Skeletal Muscle ◽

Resistance Exercise ◽

Protein Complex ◽

Human Skeletal Muscle ◽

Target Of Rapamycin ◽

Mechanistic Target Of Rapamycin

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Effect of consecutive repeated sprint and resistance exercise bouts on acute adaptive responses in human skeletal muscle

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00351.2009 ◽

2009 ◽

Vol 297 (5) ◽

pp. R1441-R1451 ◽

Cited By ~ 62

Author(s):

Vernon G. Coffey ◽

Bozena Jemiolo ◽

Johann Edge ◽

Andrew P. Garnham ◽

Scott W. Trappe ◽

...

Keyword(s):

Skeletal Muscle ◽

Resistance Exercise ◽

Acute Exercise ◽

Vastus Lateralis ◽

Ring Finger ◽

Exercise Bout ◽

Induced Response ◽

Repeated Sprints ◽

Leg Extension ◽

Repeated Sprint

We examined acute molecular responses in skeletal muscle to repeated sprint and resistance exercise bouts. Six men [age, 24.7 ± 6.3 yr; body mass, 81.6 ± 7.3 kg; peak oxygen uptake, 47 ± 9.9 ml·kg−1·min−1; one repetition maximum (1-RM) leg extension 92.2 ± 12.5 kg; means ± SD] were randomly assigned to trials consisting of either resistance exercise (8 × 5 leg extension, 80% 1-RM) followed by repeated sprints (10 × 6 s, 0.75 N·m torque·kg−1) or vice-versa. Muscle biopsies from vastus lateralis were obtained at rest, 15 min after each exercise bout, and following 3-h recovery to determine early signaling and mRNA responses. There was divergent exercise order-dependent phosphorylation of p70 S6K (S6K). Specifically, initial resistance exercise increased S6K phosphorylation (∼75% P < 0.05), but there was no effect when resistance exercise was undertaken after sprints. Exercise decreased IGF-I mRNA following 3-h recovery (∼50%, P = 0.06) independent of order, while muscle RING finger mRNA was elevated with a moderate exercise order effect ( P < 0.01). When resistance exercise was followed by repeated sprints PGC-1α mRNA was increased (REX1-SPR2; P = 0.02) with a modest distinction between exercise orders. Repeated sprints may promote acute interference on resistance exercise responses by attenuating translation initiation signaling and exacerbating ubiquitin ligase expression. Indeed, repeated sprints appear to generate the overriding acute exercise-induced response when undertaking concurrent repeated sprint and resistance exercise. Accordingly, we suggest that sprint-activities are isolated from resistance training and that adequate recovery time is considered within periodized training plans that incorporate these divergent exercise modes.

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Leucine does not affect mechanistic target of rapamycin complex 1 assembly but is required for maximal ribosomal protein s6 kinase 1 activity in human skeletal muscle following resistance exercise

The FASEB Journal ◽

10.1096/fj.15-273474 ◽

2015 ◽

Vol 29 (10) ◽

pp. 4358-4373 ◽

Cited By ~ 23

Author(s):

William Apró ◽

Marcus Moberg ◽

D. Lee Hamilton ◽

Björn Ekblom ◽

Olav Rooyackers ◽

...

Keyword(s):

Skeletal Muscle ◽

Resistance Exercise ◽

Ribosomal Protein ◽

Human Skeletal Muscle ◽

Target Of Rapamycin ◽

S6 Kinase ◽

Mechanistic Target Of Rapamycin ◽

Ribosomal Protein S6 ◽

Ribosomal Protein S6 Kinase

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Consecutive bouts of diverse contractile activity alter acute responses in human skeletal muscle

Journal of Applied Physiology ◽

10.1152/japplphysiol.91221.2008 ◽

2009 ◽

Vol 106 (4) ◽

pp. 1187-1197 ◽

Cited By ~ 62

Author(s):

Vernon G. Coffey ◽

Henriette Pilegaard ◽

Andrew P. Garnham ◽

Brendan J. O'Brien ◽

John A. Hawley

Keyword(s):

Skeletal Muscle ◽

Resistance Exercise ◽

Endurance Exercise ◽

Contractile Activity ◽

Vastus Lateralis ◽

Mrna Level ◽

Molecular Profile ◽

Hexokinase Ii ◽

Leg Extension ◽

Acute Responses

We examined acute molecular responses in skeletal muscle to divergent exercise stimuli by combining consecutive bouts of resistance and endurance exercise. Eight men [22.9 ± 6.3 yr, body mass of 73.2 ± 4.5 kg, peak O2 uptake (V̇o2peak) of 54.0 ± 5.7 ml·kg−1·min−1] were randomly assigned to complete trials consisting of either resistance exercise (8 × 5 leg extension, 80% 1 repetition maximum) followed by a bout of endurance exercise (30 min cycling, 70% V̇o2peak) or vice versa. Muscle biopsies were obtained from the vastus lateralis at rest, 15 min after each exercise bout, and after 3 h of passive recovery to determine early signaling and mRNA responses. Phosphorylation of Akt and Akt1Ser473 were elevated 15 min after resistance exercise compared with cycling, with the greatest increase observed when resistance exercise followed cycling (∼55%; P < 0.01). TSC2-mTOR-S6 kinase phosphorylation 15 min after each bout of exercise was similar regardless of the exercise mode. The cumulative effect of combined exercise resulted in disparate mRNA responses. IGF-I mRNA content was reduced when cycling preceded resistance exercise (−42%), whereas muscle ring finger mRNA was elevated when cycling was undertaken after resistance exercise (∼52%; P < 0.05). The hexokinase II mRNA level was higher after resistance cycling (∼45%; P < 0.05) than after cycling-resistance exercise, whereas modest increases in peroxisome proliferator-activated receptor gamma coactivator-1α mRNA did not reveal an order effect. We conclude that acute responses to diverse bouts of contractile activity are modified by the exercise order. Moreover, undertaking divergent exercise in close proximity influences the acute molecular profile and likely exacerbates acute “interference.”

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Rapamycin‐insensitive mechanistic target of rapamycin regulates basal and resistance exercise‐induced muscle protein synthesis

The FASEB Journal ◽

10.1096/fj.201701422r ◽

2018 ◽

Vol 32 (11) ◽

pp. 5824-5834 ◽

Cited By ~ 20

Author(s):

Riki Ogasawara ◽

Takeshi Suginohara

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Target Of Rapamycin ◽

Mechanistic Target Of Rapamycin ◽

Exercise Induced

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High-intensity muscle contraction-mediated increases in Akt1 and Akt2 phosphorylation do not contribute to mTORC1 activation and muscle protein synthesis

Journal of Applied Physiology ◽

10.1152/japplphysiol.00578.2019 ◽

2020 ◽

Vol 128 (4) ◽

pp. 830-837 ◽

Cited By ~ 2

Author(s):

Yuki Maruyama ◽

Chisaki Ikeda ◽

Koki Wakabayashi ◽

Satoru Ato ◽

Riki Ogasawara

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Muscle Contraction ◽

High Intensity ◽

Gastrocnemius Muscle ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Target Of Rapamycin ◽

Mechanistic Target Of Rapamycin ◽

Mtorc1 Activation

High-intensity muscle contraction (HiMC) is known to induce muscle protein synthesis, a process in which mechanistic target of rapamycin (mTOR) is reported to play a critical role. However, the mechanistic details have not been completely elucidated. Here, we investigated whether Akt plays a role in regulating HiMC-induced mTORC1 activation and muscle protein synthesis using a rodent model of resistance exercise and MK2206 (an Akt kinase inhibitor). The right gastrocnemius muscle of male C57BL/6J mice aged 10 wk was isometrically contracted via percutaneous electrical stimulation (100 Hz, 5 sets of 10 3-s contractions, 7-s rest between contractions, and 3-min rest between sets), while the left gastrocnemius muscle served as a control. Vehicle or MK2206 was injected intraperitoneally 6 h before contraction. MK2206 inhibited both resting and HiMC-induced phosphorylation of Akt1 Ser-473 and Akt2 Ser-474. MK2206 also inhibited the resting phosphorylation of p70S6K and 4E-BP1, which are downstream targets of mTORC1; however, it did not inhibit the HiMC-induced increase in phosphorylation of these targets. Similarly, MK2206 inhibited the resting muscle protein synthesis, but not the resistance exercise-induced muscle protein synthesis. On the basis of these observations, we conclude that although Akt2 regulates resting mTORC1 activity and muscle protein synthesis, HiMC-induced increases in mTORC1 activity and muscle protein synthesis are Akt-independent processes. NEW & NOTEWORTHY Akt is well known to be an upstream regulator of mechanistic target of rapamycin (mTOR) and has three isoforms in mammals, namely, Akt1, Akt2, and Akt3. We found that high-intensity muscle contraction (HiMC) increases Akt1 and Akt2 phosphorylation; however, HiMC-induced increases in mTORC1 activity and muscle protein synthesis are Akt-independent processes.

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