title: Muscle p70S6K phosphorylation in response to soy and dairy rich meals in middle aged men with metabolic syndrome: a randomised crossover trial.
abstract: BACKGROUND
  The mammalian target of rapamycin (mTOR) pathway is the primary regulator of muscle protein synthesis. Metabolic syndrome (MetS) is characterized by central obesity and insulin resistance; little is known about how MetS affects the sensitivity of the mTOR pathway to feeding.
  
  
  METHODS
  The responsiveness of mTOR pathway targets such as p706Sk to a high protein meal containing either dairy or soy foods was investigated in healthy insulin sensitive middle-aged men and those presenting with metabolic syndrome (MetS). Twenty male subjects (10 healthy controls, 10 MetS) participated in a single-blinded randomized cross-over study. In a random sequence, subjects ingested energy-matched breakfasts composed predominately of either dairy-protein or soy-protein foods. Skeletal muscle biopsies were collected in the fasted state and at 2 and 4 h post-meal ingestion for the analysis of mTOR- and insulin-signalling kinase activation.
  
  
  RESULTS
  Phosphorylated Akt and Insulin receptor substrate 1 (IRS1) increased during the postabsorptive period with no difference between groups. mTOR (Ser448) and ribosomal protein S6 phosphorylation increased 2 h following dairy meal consumption only. p70S6K (Thr389) phosphorylation was increased after feeding only in the control subjects and not in the MetS group.
  
  
  CONCLUSIONS
  These data demonstrate that the consumption of a dairy-protein rich but not a soy-protein rich breakfast activates the phosphorylation of mTOR and ribosomal protein S6, required for protein synthesis in human skeletal muscle. Unlike healthy controls, subjects with MetS did not increase muscle p70S6K(Thr389) phosphorylation in response to a mixed meal.
  
  
  BACKGROUND
  This trial was registered with the Australian New Zealand Clinical Trials Registry (ANZCTR) as ACTRN12610000562077.
authors.affiliation: Molecular Nutrition Unit, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria Australia.
authors.forename: Petra
authors.initials: P
authors.lastname: Gran
authors.affiliation: Molecular Nutrition Unit, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria Australia.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Larsen
authors.affiliation: Molecular Nutrition Unit, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria Australia.
authors.forename: Maxine
authors.initials: M
authors.lastname: Bonham
authors.affiliation: Molecular Nutrition Unit, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria Australia.
authors.forename: Aimee L
authors.initials: AL
authors.lastname: Dordevic
authors.affiliation: Metabolomics Australia, University of Melbourne, Parkville, Victoria Australia.
authors.forename: Thusitha
authors.initials: T
authors.lastname: Rupasinghe
authors.affiliation: Metabolomics Australia, University of Melbourne, Parkville, Victoria Australia.
authors.forename: Claudio
authors.initials: C
authors.lastname: Silva
authors.affiliation: Metabolomics Australia, University of Melbourne, Parkville, Victoria Australia.
authors.forename: Amsha
authors.initials: A
authors.lastname: Nahid
authors.affiliation: Metabolomics Australia, University of Melbourne, Parkville, Victoria Australia.
authors.forename: Dedreia
authors.initials: D
authors.lastname: Tull
authors.affiliation: School of Medicine, Deakin University, Waurn Ponds, Victoria Australia.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Sinclair
authors.affiliation: The Liggins Institute, Faculty of Medical and Science Health, University of Auckland, 85 Park Road, Grafton, Private Bag 92019, Auckland, 1023 New Zealand.
authors.forename: Cameron J
authors.initials: CJ
authors.lastname: Mitchell
authors.affiliation: Molecular Nutrition Unit, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria Australia ; The Liggins Institute, Faculty of Medical and Science Health, University of Auckland, 85 Park Road, Grafton, Private Bag 92019, Auckland, 1023 New Zealand.
authors.forename: David
authors.initials: D
authors.lastname: Cameron-Smith