PSIV-1 - Differential Gene Expression of Methionine-folate Cycle Enzymes in Heifers Supplemented with One-carbon Metabolites

Abstract: The objectives of this study were to investigate the impacts of varying levels of one-carbon metabolite [OCM: folate (FA), vitamin B12 (B12), methionine (Met), and choline (Chol)] supplementation on the gene expression of hepatic methionine-folate cycle enzymes at d 14 of the estrous cycle in beef heifers. In this study, 30 Angus beef heifers were fed a standard diet (SHD: 75% alfalfa/grass hay mix, 21% corn silage, and 4% mineral pellet without rumensin) and assigned to one of five different structures (0XNEG = SHD + 0.9% saline injection; 0XPOS = SHD + rumen protected Met fed at 0.08% inclusion on a DM basis + 60 g/d rumen protected Chol + 0.9% saline injection; 0.5X = SHD + same Met and Chol + 5 mg B12 + 80 mg FA; 1X = SHD + same Met and Chol + 10 mg B12 + 160 FA; and 2X = SHD + same Met and Chol + 20 mg B12 + 320 mg FA) with injections given at d 0 and 7 of the estrous cycle. Heifers were harvested on d 14 of the estrous cycle. Real-time PCR analysis followed by statistical contrasts revealed that combined B12 and FA treatments had greater (P < 0.05) methionine adenosyltransferase 2A (MAT2A), methionine adenosyltransferase 2B (MAT2B), and protein arginine methyltransferase 1 (PRMT1) expression compared with 0XPOS. The FA treatments yielded linear increases (P < 0.05) in MAT2A, MAT2B, PRMT1, glycine N-methyltransferase (GNMT), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) and tended (P < 0.072) to linearly increase methylenetetrahydrofolate reductase (MTHFR) expression. DNA methyltransferase 1, DNA methyltransferase 3A, and methionine adenosyltransferase 1A, were unaltered by treatments. Data are interpreted to imply that strategic supplementation of OCM can increase expression of key genes in the one-carbon metabolic pathways found in the liver of beef heifers.