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Effects of amino acids on phosphorylation of S6 ribosomal protein in mammary epithelial cells
Author(s) -
APPUHAMY JAYASOORIYA RANGA,
Hanigan Mark D,
Escobar Jeffery
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.738.13
Subject(s) - ribosomal protein s6 , phosphorylation , amino acid , protein biosynthesis , ribosomal protein , chemistry , protein phosphorylation , biochemistry , biology , microbiology and biotechnology , ribosome , rna , gene , protein kinase a
Protein synthesis is a highly regulated process responding to various signals including hormones and supply of energy and amino acids. The interactions of these signals have not been explored in bovine mammary epithelial (BME) cells. The objective of this study was to investigate the effects of individual amino acid deprivation on phosphorylation of ribosomal protein S6 which regulates protein synthesis. An established BME cell line (MAC‐T) was used as a model. Cells were grown to 85% confluence, serum starved for 12 h, and treated with serum‐free media containing all amino acids (Ctrl) or media singly deprived of Arg, His, Ile, Leu, Lys, Met, Phe, Thr, Trp, or Val for one hour. Then, cells were lysed, and cell lysates were subjected to Western immunoblotting using an antibody against phosphorylated S6 (rpS6 235/236 ). Membranes were subsequently stripped and reprobed with an antibody against total S6. Results were expressed as ratios of pS6 235/236 : total S6 which is indicative of the S6 phosphorylation state. Deprivation of Arg, Val, and Ile reduced ( P < 0.05) S6 phosphorylation by 96%, 90%, and 85%, respectively, compared to Ctrl. Deprivation of Phe and Leu reduced ( P < 0.10) S6 phosphorylation by 45% and 30%, respectively. Branched chain amino acids, Arg, and Phe appeared to have key roles in regulation of protein translation initiation in BME cells.