PMID- 25439029
OWN - NLM
STAT- MEDLINE
DCOM- 20150806
LR  - 20211203
IS  - 1879-0739 (Electronic)
IS  - 0271-5317 (Linking)
VI  - 34
IP  - 11
DP  - 2014 Nov
TI  - Increasing leucine concentration stimulates mechanistic target of rapamycin 
      signaling and cell growth in C2C12 skeletal muscle cells.
PG  - 1000-7
LID - S0271-5317(14)00196-1 [pii]
LID - 10.1016/j.nutres.2014.09.011 [doi]
AB  - Leucine is a key amino acid for initiating translation in muscle cells, but the 
      dose-dependent effects of leucine on intracellular signaling are poorly 
      characterized. This study examined the effect that increasing doses of leucine 
      would have on changes in mechanistic target of rapamycin (mTOR)-mediated 
      signaling, rates of protein synthesis, and cell size in C2C12 cells. We 
      hypothesized that a leucine "threshold" exists, which represents the minimum 
      stimulus required to initiate mTOR signaling in muscle cells. Acute exposure to 
      1.5, 3.2, 5.0, and 16.1 mM leucine increased phosphorylation of mTOR(Ser2448) 
      (~1.4-fold; P < .04), 4E-BP1 (Thr37/46) (~1.9-fold; P < .001), and rpS6(Ser235/6) 
      (~2.3-fold; P < .001). However, only p70S6k(Thr389) exhibited a dose-dependent 
      response to leucine with all treatments higher than control (~4-fold; P < .001) 
      and at least 5 mM higher than the 1.5-mM concentration (1.2-fold; P < .02). Rates 
      of protein synthesis were not altered by any treatment. Seven days of exposure to 
      0.5, 1.5, 5.0, and 16.5 mM leucine resulted in an increase in cell size in at 
      least 5 mM treatments (~1.6-fold, P < .001 vs control). Our findings indicate 
      that even at low leucine concentrations, phosphorylation of proteins regulating 
      translation initiation signaling is enhanced. The phosphorylation of 
      p70S6k(Thr389) follows a leucine dose-response relationship, although this was 
      not reflected by the acute protein synthetic response. Nevertheless, under the 
      conditions of the present study, it appears that leucine concentrations of at 
      least 5 mM are necessary to enhance cell growth.
CI  - Copyright (c) 2014 Elsevier Inc. All rights reserved.
FAU - Areta, Jose L
AU  - Areta JL
AD  - Exercise and Nutrition Research Group, School of Medical Sciences, RMIT 
      University, Melbourne, Victoria, Australia.
FAU - Hawley, John A
AU  - Hawley JA
AD  - Exercise and Nutrition Research Group, School of Medical Sciences, RMIT 
      University, Melbourne, Victoria, Australia; Research Institute for Sport and 
      Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom. 
      Electronic address: john.hawley@acu.edu.au.
FAU - Ye, Ji-Ming
AU  - Ye JM
AD  - Molecular Pharmacology for Diabetes Group, Health Innovations Research Institute 
      and School of Health Sciences, RMIT University, Melbourne, Victoria, Australia.
FAU - Chan, M H Stanley
AU  - Chan MH
AD  - Molecular Pharmacology for Diabetes Group, Health Innovations Research Institute 
      and School of Health Sciences, RMIT University, Melbourne, Victoria, Australia.
FAU - Coffey, Vernon G
AU  - Coffey VG
AD  - School of Exercise and Nutrition Sciences and Institute of Health and Biomedical 
      Innovation, Queensland University of Technology, Brisbane, Australia.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20141002
PL  - United States
TA  - Nutr Res
JT  - Nutrition research (New York, N.Y.)
JID - 8303331
RN  - 0 (Adaptor Proteins, Signal Transducing)
RN  - 0 (Carrier Proteins)
RN  - 0 (Cell Cycle Proteins)
RN  - 0 (Eif4ebp1 protein, mouse)
RN  - 0 (Eukaryotic Initiation Factors)
RN  - 0 (Phosphoproteins)
RN  - 0 (Ribosomal Protein S6)
RN  - 0 (proline-rich Akt substrate, 40 kDa protein, mouse)
RN  - 0 (ribosomal protein S6, mouse)
RN  - EC 2.7.1.1 (mTOR protein, mouse)
RN  - EC 2.7.11.1 (Ribosomal Protein S6 Kinases, 70-kDa)
RN  - EC 2.7.11.1 (TOR Serine-Threonine Kinases)
RN  - GMW67QNF9C (Leucine)
SB  - IM
MH  - Adaptor Proteins, Signal Transducing
MH  - Animals
MH  - Carrier Proteins/genetics/metabolism
MH  - Cell Cycle Proteins
MH  - Cell Line
MH  - Dose-Response Relationship, Drug
MH  - Eukaryotic Initiation Factors
MH  - Leucine/*blood/*pharmacology
MH  - Mice
MH  - Muscle Fibers, Skeletal/cytology/*drug effects/metabolism
MH  - Phosphoproteins/genetics/metabolism
MH  - Phosphorylation
MH  - Protein Biosynthesis/drug effects
MH  - Ribosomal Protein S6/genetics/metabolism
MH  - Ribosomal Protein S6 Kinases, 70-kDa/genetics/metabolism
MH  - *Signal Transduction
MH  - TOR Serine-Threonine Kinases/genetics/*metabolism
OTO - NOTNLM
OT  - Amino acids
OT  - Anabolic signaling
OT  - C2C12
OT  - Protein synthesis
OT  - Skeletal muscle
OT  - mTOR
EDAT- 2014/12/03 06:00
MHDA- 2015/08/08 06:00
CRDT- 2014/12/03 06:00
PHST- 2013/10/31 00:00 [received]
PHST- 2014/09/23 00:00 [revised]
PHST- 2014/09/26 00:00 [accepted]
PHST- 2014/12/03 06:00 [entrez]
PHST- 2014/12/03 06:00 [pubmed]
PHST- 2015/08/08 06:00 [medline]
AID - S0271-5317(14)00196-1 [pii]
AID - 10.1016/j.nutres.2014.09.011 [doi]
PST - ppublish
SO  - Nutr Res. 2014 Nov;34(11):1000-7. doi: 10.1016/j.nutres.2014.09.011. Epub 2014 
      Oct 2.