PMID- 37782762 OWN - NLM STAT- MEDLINE DCOM- 20231101 LR - 20231101 IS - 1525-3163 (Electronic) IS - 0021-8812 (Print) IS - 0021-8812 (Linking) VI - 101 DP - 2023 Jan 3 TI - Effects of L-arginine and arginine-arginine dipeptide on amino acids uptake and alphaS1-casein synthesis in bovine mammary epithelial cells. LID - 10.1093/jas/skad339 [doi] LID - skad339 AB - Arginine (Arg), as an important functional amino acids (AA), is essential for milk protein synthesis in lactating ruminants. Arg shares transporters with cationic and neutral AA in mammary epithelial cells. Therefore, competitive inhibition might exist among these AA in uptake by mammary epithelial cells. In this study, cultured bovine mammary epithelial cells (BMEC) were used as the model to investigate whether the availability of L-Arg (0.7, 1.4, 2.8, 5.6, and 11.2 mM) affects the uptake of other AA and if this related to alphaS1-casein synthesis, and whether Arginine-Arginine (Arg-Arg) substituting part of free L-Arg can alleviate competitive inhibition among Arg and other AA, so as to promote alphaS1-casein synthesis. Our results showed that 2.8 mM L-Arg generated the greatest positive effects on alphaS1-casein synthesis and the activation of mammalian target of rapamycin (mTOR) signaling pathway (P < 0.01). With L-Arg supply increasing from 0.7 to 11.2 mM, the net-uptake of other AA (except Glu and Ala) decreased linearly and quadratically (Plinear < 0.01; Pquadratic < 0.01). Compared with 2.8 mM, the net-uptake of essential amino acids (EAA) and total amino acids (TAA) were lower at 11.2 mM L-Arg group, while greater at 1.4 mM L-Arg group (P < 0.01). Arg-Arg dipeptide replacing 10% free L-Arg increased alphaS1-casein synthesis (P < 0.05), net-uptake of EAA and TAA, as well as phosphorylation level of mTOR and p70 ribosomal protein S6 kinase (P70S6K) and mRNA expression of oligopeptide transporter 2 (PepT2; P < 0.01). These observations suggested that the increased alphaS1-casein synthesis by 10% Arg-Arg dipeptide might be related to the increase of AA availability and the activation of mTOR signaling pathway in BMEC. CI - (c) The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. FAU - Sun, Mei AU - Sun M AD - College of Animal Science, Inner Mongolia Agricultural University, Hohhot, 010000, China. FAU - Cao, Yue AU - Cao Y AD - College of Animal Science, Inner Mongolia Agricultural University, Hohhot, 010000, China. FAU - Xing, Yuanyuan AU - Xing Y AD - College of Animal Science, Inner Mongolia Agricultural University, Hohhot, 010000, China. AD - Key Laboratory of Animal Nutrition and Feed Science, Universities of Inner Mongolia Autonomous Region, Hohhot, 010000, China. FAU - Mu, Xiaojia AU - Mu X AD - College of Animal Science, Inner Mongolia Agricultural University, Hohhot, 010000, China. FAU - Hao, Yihong AU - Hao Y AD - College of Animal Science, Inner Mongolia Agricultural University, Hohhot, 010000, China. FAU - Yang, Jing AU - Yang J AD - College of Animal Science, Inner Mongolia Agricultural University, Hohhot, 010000, China. FAU - Niu, Xiaoyu AU - Niu X AD - College of Animal Science, Inner Mongolia Agricultural University, Hohhot, 010000, China. FAU - Li, Dabiao AU - Li D AD - College of Animal Science, Inner Mongolia Agricultural University, Hohhot, 010000, China. AD - Key Laboratory of Animal Nutrition and Feed Science, Universities of Inner Mongolia Autonomous Region, Hohhot, 010000, China. LA - eng GR - 2022ZY0196/The Central Government Guides Local Science and Technology Development Fund/ PT - Journal Article PL - United States TA - J Anim Sci JT - Journal of animal science JID - 8003002 RN - 0 (Caseins) RN - 94ZLA3W45F (Arginine) RN - 0 (Dipeptides) RN - EC 2.7.11.1 (TOR Serine-Threonine Kinases) RN - 0 (Amino Acids, Essential) RN - 0 (Amino Acids) RN - 0 (Milk Proteins) SB - IM MH - Female MH - Cattle MH - Animals MH - *Caseins/metabolism MH - *Arginine/pharmacology/metabolism MH - Lactation MH - Dipeptides/metabolism/pharmacology MH - TOR Serine-Threonine Kinases/metabolism MH - Mammary Glands, Animal/metabolism MH - Amino Acids, Essential/metabolism MH - Amino Acids/metabolism MH - Milk Proteins/metabolism MH - Epithelial Cells/metabolism MH - Mammals/metabolism PMC - PMC10590174 OAB - Arginine (Arg) availability has been demonstrated to affect milk protein synthesis in dairy cows. Competitive inhibition exists among amino acids (AA) in uptake by mammary epithelial cells. This study aims to explore whether the availability of L-Arg affects the uptake of other AA by bovine mammary epithelial cells (BMEC) and if this is related to alphaS1-casein synthesis, and whether Arginine-Arginine (Arg-Arg) dipeptide substituting part of free L-Arg can alleviate competitive inhibition among Arg and other AA, so as to promote alphaS1-casein synthesis in BMEC. Our results showed that 2.8 mM L-Arg is the appropriate concentration for alphaS1-casein synthesis. With L-Arg supply increasing from 0.7 to 11.2 mM, the net-uptake of most AA decreased linearly and quadratically. Arg-Arg dipeptide substituting 10% of free L-Arg increased alphaS1-casein synthesis and the net-uptake of AA as well as expression of proteins related to mammalian target of rapamycin (mTOR) signaling pathway and mRNA expression of oligopeptide transporter 2 (PepT2). The positive effects of 10% Arg-Arg dipeptide on alphaS1-casein synthesis may be related to the increase of AA availability and the activation of mTOR signaling pathway. OABL- eng OTO - NOTNLM OT - amino acids uptake OT - arginine OT - bovine mammary epithelial cells OT - casein synthesis OT - dipeptide COIS- We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, and there is no professional or other personal interest of any nature or kind in any product, service, and/or company that could be construed as influencing the content of this paper. EDAT- 2023/10/02 18:41 MHDA- 2023/11/01 12:45 PMCR- 2024/10/02 CRDT- 2023/10/02 14:42 PHST- 2023/06/06 00:00 [received] PHST- 2023/09/29 00:00 [accepted] PHST- 2024/10/02 00:00 [pmc-release] PHST- 2023/11/01 12:45 [medline] PHST- 2023/10/02 18:41 [pubmed] PHST- 2023/10/02 14:42 [entrez] AID - 7287835 [pii] AID - skad339 [pii] AID - 10.1093/jas/skad339 [doi] PST - ppublish SO - J Anim Sci. 2023 Jan 3;101:skad339. doi: 10.1093/jas/skad339.