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Title:Effects of essential amino acids supply and body condition prepartum on antioxidant, inflammation and mechanistic target of rapamycin pathways in adipose tissue during the periparturient period
Author(s):Liang, Yusheng
Director of Research:Loor, Juan J
Doctoral Committee Chair(s):Loor, Juan J
Doctoral Committee Member(s):Drackley, James K; Pan, Yuan-Xiang; McCann, Joshua C
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):amino acid
body condition
adipose tissue
transition period
Abstract:In non-ruminants, adipose tissue is responsive to amino acid supply, can utilize them as fuels, or for protein synthesis regulated in part via insulin and mechanistic target of rapamycin (mTOR) signaling. Nuclear factor, erythroid-derived 2-like 2 (NFE2L2, formerly Nrf2) is a key transcription factor controlling cellular oxidative stress (OS) in non-ruminants. Our research examined the effects of rumen-protected methionine (RPM) supply or body condition prepartum on pathways associated with mTOR and NFE2L2 pathways in subcutaneous adipose tissue (SAT) during the periparturient period, respectively. Sixty multiparous Holstein cows were assigned from –28 to 60 d relative to parturition to a basal diet (control; 1.47 Mcal/kg of DM and 15.3% CP prepartum; 1.67 Mcal/kg and 17.7% CP postpartum) or the control plus ethyl-cellulose RPM. The RPM was fed individually at a rate of 0.09% of DMI prepartum and 0.10% postpartum. Enhanced Met supply led to greater overall mRNA abundance of Gln (SLC38A1), Glu (SLC1A1), L-type AA (Met, Leu, Val, Phe; SLC3A2), and neutral AA (SLC1A5) transporters along with greater gene expression of glutathione (GSH) metabolism-related genes. Furthermore, it upregulated protein abundance of insulin-responsive proteins phosphorylated (p) protein kinase B (p-AKT). A diet×day interaction was observed for mTOR protein abundance due to greater values for RPM cows at 30 d postpartum compared with controls. Additionally, supply of Met resulted in an overall upregulation of protein abundance of glutathione peroxidase 1 (GPX1), GPX3, glutathione S-transferase mu 1 (GSTM1), and glutathione S-transferase alpha 4 all related to GSH metabolism. There was a diet×day effect for protein abundance of NFE2L2 and its repressor kelch like ECH associated protein 1 due to lower values at 30 d in cows fed Met versus controls. Therefore, the data suggest that exogenous Met may play a role in activating GSH metabolism and the anti-oxidant NFE2L2 pathways in SAT. Besides, the mTOR pathway in SAT adapts to the change in the physiologic state during the periparturient period. Twenty-two multiparous Holstein cows were retrospectively classified into a high body condition score (HBCS; n = 11, BCS ≥ 3.5) or normal BCS (NBCS; n = 11, BCS ≤ 3.17) on d 28 before parturition. Cows were fed a corn silage- and wheat straw-based total mixed ration (TMR) during late-prepartum and a corn silage- and alfalfa hay-based TMR postpartum. Cows in HBCS had greater overall plasma non-esterified fatty acid concentrations due to marked increases at 7 and 15 d postpartum. Plasma concentrations of reactive oxygen species (ROS) increased after parturition regardless of treatment. Overall ROS concentrations in SAT were greater in HBCS cows. Although HBCS cows had greater overall total protein abundance of NFE2L2 in SAT, the ratio of p-NFE2L2-to-total NFE2L2 was lower suggesting a decrease in the activity of this antioxidant system. Overall mRNA abundance of the GSH metabolism-related genes along with protein abundance of GSTM1 was greater in HBCS cows. Data suggest that HBCS cows might experience greater systemic OS after parturition, while the increased abundance of mRNA and protein components of the GSH metabolism pathway in SAT might help alleviate tissue oxidant status. Overconditioning during the late prepartum period leads to lower activation of AKT (p-AKT/total AKT) and more pronounced lipolysis postpartum; however, adipose tissue in over-conditioned cows might trigger compensatory mechanisms. We further tested the effects of enhanced amino acids (Met, Leu, Ile, Val, Arg) on protein abundance of amino acid transporter, insulin signaling, and GSH metabolism-related proteins with or without challenges (hydrogen peroxide or C2:0-ceramide) using bovine adipose explants. Enhanced amino acid supply promotes the activation of mTOR and may potentially help maintain adipose tissue functionality. Overall, these responses suggested mTOR and NFE2L2 pathways in bovine SAT are responsive to amino acid supply and BCS prepartum.
Issue Date:2021-07-08
Type:Thesis
URI:http://hdl.handle.net/2142/113262
Rights Information:Copyright 2021 Yusheng Liang
Date Available in IDEALS:2022-01-12
Date Deposited:2021-08


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