title: Occurrence of selenoprotein enzyme activities and mRNA in bovine mammary tissue.
abstract: To elucidate the possible role of selenoproteins for milk formation and mammary gland physiology, the activities of selenoprotein enzymes and the expression of selenoprotein genes were studied in the bovine mammary gland. Messenger RNA was demonstrated for selenoprotein P, thioredoxin reductase 1, and for glutathione peroxidase (GPx) 1, 3, and 4. Significant differences in mRNA expression between the cows were seen for GPx 1 and GPx 3. The enzyme activity of glutathione peroxidase varied approximately 16-fold among cows, and the activity of thioredoxin reductase and the concentration of soluble Se varied approximately 6-fold among cows. There were positive correlations between glutathione peroxidase activity, thioredoxin reductase activity, and soluble Se, the correlation between glutathione peroxidase activity and soluble Se being the strongest. Furthermore, selenoprotein P expression correlated with GPx 1 mRNA expression and with soluble Se. There was also a correlation between glutathione peroxidase activity and the mRNA expression of GPx 1. The general conclusion from the data was that the activity of glutathione peroxidase and thioredoxin reductase and the mRNA expression of selenoprotein P and GPx 1 and 3 were influenced by Se status, but the expression of GPx 4 and thioredoxin reductase 1 were not. These results indicate that the Se status in mammary tissue is an important regulator of selenoprotein activity and expression, but that other factors are also in operation.
authors.affiliation: Biomedical Nutrition, Faculty of Engineering LTH, Lund University, Lund, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Bruzelius
authors.forename: T
authors.initials: T
authors.lastname: Hoac
authors.forename: R
authors.initials: R
authors.lastname: Sundler
authors.forename: G
authors.initials: G
authors.lastname: Onning
authors.forename: B
authors.initials: B
authors.lastname: Akesson
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002417:Cattle / Q000378:metabolism*; D005260:Female; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000737:chemistry / Q000201:enzymology*; D009693:Nucleic Acid Hybridization; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D012333:RNA, Messenger / Q000032:analysis*; D012643:Selenium / Q000032:analysis; D051149:Selenoprotein P / Q000235:genetics; D051140:Selenoproteins / Q000378:metabolism*; D012995:Solubility; D054481:Thioredoxin Reductase 1; D013880:Thioredoxin-Disulfide Reductase / Q000235:genetics / Q000378:metabolism; D000094765:Glutathione Peroxidase GPX1
chemical_list: D012333:RNA, Messenger; D051149:Selenoprotein P; D051140:Selenoproteins; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase; D054481:Thioredoxin Reductase 1; D013880:Thioredoxin-Disulfide Reductase; D012643:Selenium; D000094765:Glutathione Peroxidase GPX1