PMID- 24183687
OWN - NLM
STAT- MEDLINE
DCOM- 20151014
LR  - 20211203
IS  - 1525-3198 (Electronic)
IS  - 0022-0302 (Linking)
VI  - 97
IP  - 1
DP  - 2014
TI  - Effects of AMP-activated protein kinase (AMPK) signaling and essential amino 
      acids on mammalian target of rapamycin (mTOR) signaling and protein synthesis 
      rates in mammary cells.
PG  - 419-29
LID - S0022-0302(13)00734-0 [pii]
LID - 10.3168/jds.2013-7189 [doi]
AB  - Regulation of mammary protein synthesis potentially changes the relationships 
      between AA supply and milk protein output represented in current nutrient 
      requirement models. Glucose and AA regulate muscle protein synthesis via cellular 
      signaling pathways involving mammalian target of rapamycin (mTOR) and 
      AMP-activated protein kinase (AMPK). The objective of this study was to 
      investigate the effects of essential AA (EAA) and acetate or glucose on mTOR and 
      AMPK signaling pathways and milk protein synthesis rates. A bovine mammary 
      epithelial cell line, MAC-T, was subjected to different media containing 0 or 3.5 
      mmol/L EAA concentrations with 0 or 5 mmol/L acetate or 0 or 17.5 mmol/L glucose 
      in 2 separate 2 x 2 factorial studies. In a separate set of experiments, 
      lactogenic bovine mammary tissue slices were subjected to the same treatments 
      except that the low EAA treatment contained a low level of EAA (0.18 mmol/L). 
      Supplementation of EAA enhanced phosphorylation of mTOR (Ser2448) and eukaryotic 
      initiation factor 4E binding protein 1 (4EBP1, Thr37/46), and reduced 
      phosphorylation of eukaryotic elongation factor 2 (eEF2, Thr56) in MAC-T cells. 
      Concentration of ATP and phosphorylation of AMPK increased and decreased, 
      respectively, in the presence of EAA in MAC-T cells. Acetate, EAA, or glucose 
      numerically reduced AMPK phosphorylation by about 16% in mammary tissue slices. 
      Provision of EAA increased phosphorylation of mTOR and 4EBP1, intracellular total 
      EAA concentration, and casein synthesis rates in mammary tissue slices, 
      irrespective of the presence of acetate or glucose in the medium. Phosphorylation 
      of mTOR had a marginally negative association with AMPK phosphorylation, which 
      was positively related to eEF2 phosphorylation. Casein synthesis rates were 
      positively and more strongly linked to mTOR phosphorylation than the negative 
      link between eEF2 phosphorylation and casein synthesis rates. A 100% increase in 
      mTOR phosphorylation was associated with an increase in the casein synthesis rate 
      of 0.74%.h(-1), whereas a 100% increase in eEF2 phosphorylation was related to a 
      decline in the casein synthesis rate of 0.33%.h(-1). Although AMPK 
      phosphorylation was responsive to cellular energy status and had a negative 
      effect on mTOR-mediated signals in bovine mammary epithelial cells, its effect on 
      milk protein synthesis rates appeared to be marginal compared with the 
      mTOR-mediated regulation of milk protein synthesis by EAA.
CI  - Copyright (c) 2014 American Dairy Science Association. Published by Elsevier Inc. 
      All rights reserved.
FAU - Appuhamy, J A D R N
AU  - Appuhamy JA
AD  - Department of Dairy Science, Virginia Polytechnic Institute and State University, 
      Blacksburg 24061. Electronic address: jaappuhamy@ucdavis.edu.
FAU - Nayananjalie, W A
AU  - Nayananjalie WA
AD  - Department of Dairy Science, Virginia Polytechnic Institute and State University, 
      Blacksburg 24061.
FAU - England, E M
AU  - England EM
AD  - Department of Animal and Poultry Science, Virginia Polytechnic Institute and 
      State University, Blacksburg 24061.
FAU - Gerrard, D E
AU  - Gerrard DE
AD  - Department of Animal and Poultry Science, Virginia Polytechnic Institute and 
      State University, Blacksburg 24061.
FAU - Akers, R M
AU  - Akers RM
AD  - Department of Dairy Science, Virginia Polytechnic Institute and State University, 
      Blacksburg 24061.
FAU - Hanigan, M D
AU  - Hanigan MD
AD  - Department of Dairy Science, Virginia Polytechnic Institute and State University, 
      Blacksburg 24061.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20131101
PL  - United States
TA  - J Dairy Sci
JT  - Journal of dairy science
JID - 2985126R
RN  - 0 (Amino Acids, Essential)
RN  - 0 (Milk Proteins)
RN  - EC 2.7.11.1 (TOR Serine-Threonine Kinases)
RN  - EC 2.7.11.31 (AMP-Activated Protein Kinases)
RN  - IY9XDZ35W2 (Glucose)
SB  - IM
MH  - AMP-Activated Protein Kinases/genetics/*metabolism
MH  - Amino Acids, Essential/*pharmacology
MH  - Animals
MH  - Cattle
MH  - Cell Line
MH  - Epithelial Cells/*metabolism
MH  - Female
MH  - Glucose/pharmacology
MH  - Mammary Glands, Animal/cytology
MH  - Milk Proteins/*biosynthesis
MH  - Particle Size
MH  - Phosphorylation
MH  - Protein Biosynthesis
MH  - *Signal Transduction
MH  - TOR Serine-Threonine Kinases/genetics/*metabolism
OTO - NOTNLM
OT  - AMP-activated protein kinase (AMPK)
OT  - casein synthesis
OT  - energy substrate
OT  - essential amino acid
EDAT- 2013/11/05 06:00
MHDA- 2015/10/16 06:00
CRDT- 2013/11/05 06:00
PHST- 2013/06/26 00:00 [received]
PHST- 2013/08/23 00:00 [accepted]
PHST- 2013/11/05 06:00 [entrez]
PHST- 2013/11/05 06:00 [pubmed]
PHST- 2015/10/16 06:00 [medline]
AID - S0022-0302(13)00734-0 [pii]
AID - 10.3168/jds.2013-7189 [doi]
PST - ppublish
SO  - J Dairy Sci. 2014;97(1):419-29. doi: 10.3168/jds.2013-7189. Epub 2013 Nov 1.