Lipotropes alter casein gene expression in bovine mammary acinar culture

Lipotropes (methyl group containing nutrients, including methionine and cho line, folic acid, and vitamin B-12) are essential for cell proliferation an d differentiation of mammary tissues. Lipotropes interact in the supply and regulation of intracellular methyl group pools, thereby affecting synthesi s and methylation of DNA. To determine the effect of lipotropes on milk pro tein gene expression, acini isolated from mammary tissues of lactating cows were cultured in one of three treatment media: (I) control, (2) lipotrope deficient, and (3) lipotrope supplemented. beta-Casein mRNA was determined by Northern blotting, and milk protein secretion Mns measured by a phase-ch ase method. The level of beta-casein mRNA it as lower in cells grown in lip otrope-deficient medium than in cells grown in the lipotrope-supplemented a nd control media. Acinar cells cultured in lipotrope-deficient medium also had approximately threefold less milk protein secretion than that of cells in either control or lipotrope-supplemented media. Protein secretion did no t differ in the control and lipotrope-supplemented groups. The present stud y indicates that lipotrope deficiency suppresses total protein secretion an d beta-casein gene expression in bovine mammary alveolar epithelial cells i n culture. (C) Elsevier Science Inc. 1999. All rights reserved.