Abstract #W72
Section: Physiology and Endocrinology (posters)
Session: Physiology and Endocrinology 2
Format: Poster
Day/Time: Wednesday 7:30 AM–9:30 AM
Location: Exhibit Hall A
Session: Physiology and Endocrinology 2
Format: Poster
Day/Time: Wednesday 7:30 AM–9:30 AM
Location: Exhibit Hall A
# W72
Increasing supply of Met and Arg relative to Lys while maintaining Thr:Phe, Lys:Thr, Lys:His, and Lys:Val ratios alters casein protein abundance via amino acid-induced upstream mechanistic target of rapamycin signaling pathway and circadian clock in bovine mammary epithelial cells.
L. Y. Hu1,2, Y. F. Chen1, I. M. Cortes2,3, D. N. Coleman*2, H. Y. Dai2,4, C. Parys5, M. Z. Wang1, J. J. Loor2, 1College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China, 2Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL, 3Agricultural and Animal Production Department, UAM-Xochimilco, Mexico City, Mexico, 4College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, China, 5Evonik Nutrition & Care GmbH, Hanau-Wolfgang, Germany.
Key Words: Met and Arg availability, mechanistic target of rapamycin (mTOR) signaling pathway, circadian clock
Increasing supply of Met and Arg relative to Lys while maintaining Thr:Phe, Lys:Thr, Lys:His, and Lys:Val ratios alters casein protein abundance via amino acid-induced upstream mechanistic target of rapamycin signaling pathway and circadian clock in bovine mammary epithelial cells.
L. Y. Hu1,2, Y. F. Chen1, I. M. Cortes2,3, D. N. Coleman*2, H. Y. Dai2,4, C. Parys5, M. Z. Wang1, J. J. Loor2, 1College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China, 2Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL, 3Agricultural and Animal Production Department, UAM-Xochimilco, Mexico City, Mexico, 4College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, China, 5Evonik Nutrition & Care GmbH, Hanau-Wolfgang, Germany.
Methionine (Met) and arginine (Arg) regulate casein synthesis partly via alterations in activity of the mechanistic target of rapamycin (mTOR) pathway. Whether upstream regulators and cellular energy status contribute to those responses is unknown. Recent data highlighted a putative role of the circadian clock in milk protein synthesis partly via mTOR. The objective was to determine if greater supply of Met and Arg alone or in combination altered mRNA, protein abundance and phosphorylation status of mTOR-related targets. Primary bovine mammary epithelial cells (BMEC) were incubated (n = 5 replicates/treatment) for 12 h with control medium (IPAA; Lys:Met 2.9:1, Lys:Arg 2:1) or medium supplemented with Met (LM2.5; Lys:Met 2.5:1, Lys:Arg 2:1), Arg (LA1; Lys:Met 2.9:1, Lys:Arg 1:1), or LM2.5+LA1 (Lys:Met 2.5:1, Lys:Arg 1:1). Ratios of Thr:Phe (1.05:1), Lys:Thr (1.8:1), Lys:His (2.38:1), and Lys:Val (1.23:1) were the same across treatments. Target genes were measured by RT-PCR and proteins by Western blotting. Data were analyzed as a 2 × 2 factorial arrangement of treatments with the MIXED procedure ofSAS 9.4.Phosphorylation ratio of p-TSC2:total (t) TSC2 (negative regulator of mTOR) was greater with LA1 (P = 0.001), while p-AKT:tAKT and p-AMPK:tAMPK was lower (P = 0.05, P < 0.01). In spite of this, ratio of p-mTOR:tmTOR nearly doubled with LA1 and LM2.5 (interaction P < 0.05), but such response did not prevent a decrease in casein protein abundance (CSN1S1, interaction P = 0.03). Abundance of PER1 protein nearly doubled with Met or Arg alone or in combination (interaction P < 0.01), but only LM2.5+LA1 was able to double abundance of CLOCK protein (P < 0.01). Overall, data suggest that greater supply of Met or Arg relative to Lys while holding the ratios of other essential amino acids to Lys constant could influence casein synthesis. The underlying mechanisms seem to encompass mTOR, CLOCK, and intracellular energy metabolism.
Key Words: Met and Arg availability, mechanistic target of rapamycin (mTOR) signaling pathway, circadian clock
