Preprint Article Version 1 This version is not peer-reviewed

Supplementing D-Type and L-Type Methionine and Its Precursor Alters the Expression of mRNA, Proteins and Metabolites Involved in Milk Protein Synthesis and Energy Metabolism in Bovine Mammary Cells

Version 1 : Received: 6 December 2018 / Approved: 11 December 2018 / Online: 11 December 2018 (09:45:41 CET)

How to cite: Jeon, S.W..; Conejos, J.R.; Kim, J.E..; Kim, M.J..; Lee, J.E..; Lee, B.S..; Park, J.S..; Moon, J.O..; Lee, J..; Lee, H. Supplementing D-Type and L-Type Methionine and Its Precursor Alters the Expression of mRNA, Proteins and Metabolites Involved in Milk Protein Synthesis and Energy Metabolism in Bovine Mammary Cells. Preprints 2018, 2018120122 (doi: 10.20944/preprints201812.0122.v1). Jeon, S.W..; Conejos, J.R.; Kim, J.E..; Kim, M.J..; Lee, J.E..; Lee, B.S..; Park, J.S..; Moon, J.O..; Lee, J..; Lee, H. Supplementing D-Type and L-Type Methionine and Its Precursor Alters the Expression of mRNA, Proteins and Metabolites Involved in Milk Protein Synthesis and Energy Metabolism in Bovine Mammary Cells. Preprints 2018, 2018120122 (doi: 10.20944/preprints201812.0122.v1).

Abstract

This study was conducted to investigate the effect of supplementing different types of methionine (L and D-type) and its precursor (HMBi) on milk protein synthesis using immortalized bovine mammary epithelial cell line (MAC-T Cell); D-methionine (D-Met), L-methionine (L-met) and 2-hydroxy-4-methylthiobutanoic acid I (HMBi), an isopropyl ester of the hydroxy analogue precursor of methionine. The underlying mechanism of milk protein synthesis by adding D- and L-type amino acid as well as HMBi was elucidated through omics analysis to verify the metabolism pathway. Results showed that HMBi group showed the highest beta casein mRNA expression levels compared to D- and L-Met groups and highest medium protein although not different with the L-Met treatment. The observed upregulated (>2 protein expression vs. control) and downregulated (<0.5 protein expression vs. control) proteins in L-Met, D-Met and HMBi treated groups were: 39, 77; 46, 68; and 40, 78, respectively. Interestingly, based on protein pathway analysis, L-Met treated group stimulated the ATP synthesis, PI3 kinase and pyruvate metabolism. On the other hand, the D-Met group stimulated fructose-galactose metabolism, glycolysis pathway, PI3 kinase and pyruvate metabolism. And lastly HMBi-treated group stimulated pentose phosphate pathway and glycolysis pathway. Metabolite analysis revealed that L-Met treated group resulted in the increase in 11 metabolites. On the other hand, D-Met treated group showed increase in 7 metabolites and decreased of uridine monophosphate (UMP). HMBi supplementation caused increases of 3 metabolites and decreased of UMP and N-acetyl-L-glutamate Addition of different isoforms of Met stimulated the production of intermediate metabolites for energy production. Addition of L-Met stimulated the production of energy metabolites such as pyruvate, malate, and fumarate, well-known as intermediates of Krebs cycle. On the other hand, HMBi supplementation resulted in increases of energy metabolite glucose 1-phosphate and 6-phosphogluconate. Results showed that HMBi-treated group exhibited highest expression of β-casein mRNA expression by stimulating proteins and metabolites as well as protein and metabolic pathways involved in protein and energy synthesis. As a result, HMBi-treated group resulted in highest protein concentration but not significantly different with L-Met. Both the D- and L-isoforms has considerably the same medium protein concentration and β-casein mRNA expression higher than the control. So, D- and L-Met isoforms can be used alternatively without any significant change in protein synthesis efficiency in bovine mammary epithelial cells.

Subject Areas

Methionine, milk protein synthesis, proteome, HMBi

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