Selenoprotein gene expression during selenium-repletion of selenium-deficient rats.
Selenium repletion of selenium-deficient rats with 20 micrograms selenium / kg body weight as Na2SeO3 was used as a model to investigate the mechanisms that control the distribution of the trace element to specific selenoproteins in liver and thyroid. Cytosolic glutathione peroxidase (cGSHPx), phospholipid hydroperoxide glutathione peroxidase (PHGSHPx), and iodothyronine 5'-deiodinase (IDI) activities were all transiently increased in liver 16 to 32 h after ip injection with selenium. However, only cGSHPx and PHGSHPx activities increased in the thyroid where IDI activity was already increased by selenium deficiency. These responses were owing to synthesis of the seleoproteins on newly synthesised and/or existing mRNAs. The selenoprotein mRNAs in the thyroid gland were increased two- and threefold after the transitory increases in selenoprotein activity. In contrast, there were parallel changes in selenoprotein mRNAs and enzyme activities in the liver, with no prolonged rises in mRNA levels. The organ differences suggest that increased thryotrophin (TSH) concentrations, which are known to induce thyrodial IDI and mRNA, may control the mRNAs for all the thyroidal selenoproteins investigated and be a major mechanism for the preservation of thyroidal selenoproteins when selenium supplies are limited.
Bermano
G
G
Rowett Research Institute, Bucksburn, Aberdeen, UK.
Nicol
F
F
Dyer
J A
JA
Sunde
R A
RA
Beckett
G J
GJ
Arthur
J R
JR
Hesketh
J E
JE
D000818:Animals; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics; D005979:Glutathione Peroxidase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D007274:Injections, Intraperitoneal; D007453:Iodide Peroxidase / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008297:Male; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012643:Selenium / Q000172:deficiency*; D051140:Selenoproteins; D018038:Sodium Selenite / Q000008:administration & dosage / Q000494:pharmacology*; D013961:Thyroid Gland / Q000201:enzymology / Q000378:metabolism; D013963:Thyroid Hormones / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism; D014018:Tissue Distribution
D009124:Muscle Proteins; D011506:Proteins; D012333:RNA, Messenger; D051140:Selenoproteins; D013963:Thyroid Hormones; D013972:Thyrotropin; D007453:Iodide Peroxidase; D005979:Glutathione Peroxidase; D005982:Glutathione Transferase; D012643:Selenium; D018038:Sodium Selenite