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Branched-chain amino acid supplementation alters protein abundance of mechanistic target of rapamycin (mTOR) and insulin signaling pathway components in bovine subcutaneous adipose explants.

Y. Liang

Events

06-23-2020

Abstract:

206
Branched-chain amino acid supplementation alters protein abundance of mechanistic target of rapamycin (mTOR) and insulin signaling pathway components in bovine subcutaneous adipose explants.
Y. Liang*1, N. Ma1,2, D. N. Coleman1, F. Liu1,3, Y. Li1,4, H. Y. Ding1,4, F. F. Cardoso1, F. C. Cardoso1, J. J. Loor1. 1Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana Urbana, IL, 2College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China, 3Department of Animal Science and Veterinary Medicine, Henan Agricultural University Zhengzhou, China, 4Department of Veterinary Medicine, College of Animal Science and Technology, Anhui Agricultural University Hefei, China.

Branched-chain amino acids (BCAA) are import regulators of mechanistic target of rapamycin (mTOR). In humans and rodents, increased circulating BCAA levels are positively associated with insulin resistance. The objective of this study was to investigate changes in protein abundance of mTOR and insulin signaling pathway components and AA metabolism in bovine s.c. adipose explants in response to increased supply of Leu, Ile or Val. Four Holstein cows (parity 4 � 1.4, DIM 248 � 38 before slaughter; mean � SD) were used in this study. All cows were fed a common lactation diet before slaughter. Subcutaneous adipose tissue (SAT) from the tail-head was incubated with basal media containing an “ideal” mix of essential AA (IPAA; 2.9:1 Lys:Met; 1.8:1 Lys:Thr; 2.38:1 Lys:His; 1.23:1 Lys:Val; 1.45:1 Lys:Ile; 0.85:1 Lys:Leu; 2.08:1 Lys:Arg) or IPAA supplemented with Ile, Val, and Leu to achieve a Lys:Ile of 1.29:1, Lys:Val 1.12:1, or Lys:Leu 0.78:1 for 4 h. Total protein extracted from the explants was used for Western blotting. The statistical model in SAS 9.4 included the fixed effect of Lys:Ile, Lys:Val and Lys:Leu ratios. Compared with IPAA, enhanced Leu and Ile supplementation led to greater activation of protein kinase B (AKT; p-AKT/total AKT) and mTOR (p-mTOR/total mTOR) (P < 0.05). However, compared with IPAA, Val supplementation led to lower p-mTOR (P < 0.05). Despite protein abundance of solute carrier family 38 member 1 (SLC38A1) and branched-chain ketoacid dehydrogenase kinase (BCKDK) being greater compared with IPAA, supplementation of BCAA also led to greater activation of eukaryotic elongation factor 2 (EEF2; p-EEF2/total EEF2) (P < 0.05). Furthermore, compared with increased Leu or Ile, enhanced Val supplementation led to greater abundance of SLC38A1 and BCKDK (P < 0.05). Overall, data suggest that enhanced supply of BCAA activates mTOR and insulin signaling in SAT partly due to increased transport into tissue and lower catabolism.

Keywords: branched-chain amino acid, mechanistic target of rapamycin, subcutaneous adipose tissue.

Biography: My name is Yusheng Liang and I am a third year PhD student of animal sciences from University of Illiniois.