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Whey protein increases p70S6k signaling without Akt changes in a reduced carbohydrate diet
Author(s) -
Devkota Suzanne,
Walker Denise,
Layman Donald K.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1108-d
Subject(s) - protein kinase b , medicine , endocrinology , pi3k/akt/mtor pathway , carbohydrate , phosphorylation , chemistry , p70 s6 kinase 1 , insulin , meal , area under the curve , signal transduction , biology , biochemistry
Insulin and leucine interact with the PI3K/mTOR signal cascade to initiate translational control of protein synthesis (PS). This study evaluates physiological signaling responses associated with complete meals differing in macronutrient ratios. Male rats (300g) were meal‐fed 3x/d either high carbohydrate (CHO; 55% energy from carbohydrate: 15% protein: 30% fat) or high protein (40:30:30) diet for 3 wk. Plasma, skeletal muscle and adipose were collected after 12 h fast or 30 and 90 min after a 4 g meal (PP). Measurements included plasma insulin‐area‐under‐the‐curve (I‐AUC) and phosphorylation (P) of Akt, p70S6K (S6K) and ERK1/2. The CHO group had greater I‐AUC associated with increased Akt‐P at 30 and 90 min PP. I‐AUC for PRO was reduced proportional to diet composition and Akt‐P at 30 and 90 min was not significantly different from baseline. While Akt‐P was greater in CHO group, downstream signal activation was not proportionately increased. However, PRO group had greater S6K‐P than Akt‐P. S6K‐P was increased 28% in PRO vs. CHO at 30 min and 40% at 90 min. ERK1/2‐P in the MAPK pathway did not respond to diet treatments. These data indicate physiological changes in meal composition alter the pattern of signal responses for translational controls of PS with downstream nutrient sensors exhibiting greater sensitivity to dietary protein than upstream responses to insulin. Supported by National Dairy Council and Kraft Foods