Expression of the type II iodothyronine deiodinase in cultured rat astrocytes is selenium-dependent.
The iodothyronine deiodinases are a family of selenoproteins that metabolize thyroxine and other thyroid hormones to active and inactive metabolites in a number of tissues including brain. Using primary cultures of rat astroglial cells as a model system, we demonstrate that the mRNA for the type II iodothyronine deiodinase (DII) selenoenzyme is rapidly and markedly induced by forskolin and 8-bromo-cAMP. The induction of DII activity, however, was significantly impaired by culturing cells in selenium-deficient medium for 7 days. Under such conditions, the addition of selenium resulted in a rapid increase in cAMP-induced DII activity that was dose-dependent, with maximal effects noted within 2 h. Cycloheximide blocked this effect of selenium on restoring cAMP-induced DII activity, whereas actinomycin D did not. These data demonstrate that the DII selenoenzyme is expressed in cultured astrocytes and that the induction of DII activity by cAMP analogues appears to be mediated, at least in part, by pretranslational mechanisms. Furthermore, selenium deprivation impairs the expression of DII activity at the level of translation.
Pallud
S
S
U96 INSERM-Unité de Recherche sur la Glande Thyroïde et la Regulation Hormonale, 80, rue du Général Leclerc, 94276 Le Kremlin-Bicêtre Cedex, France.
Lennon
A M
AM
Ramauge
M
M
Gavaret
J M
JM
Croteau
W
W
Pierre
M
M
Courtin
F
F
St Germain
D L
DL
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D001483:Base Sequence; D001921:Brain / Q000166:cytology / Q000201:enzymology*; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D018076:DNA, Complementary; D003609:Dactinomycin / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D007453:Iodide Peroxidase / Q000096:biosynthesis* / Q000737:chemistry; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry; D007700:Kinetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011506:Proteins; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012643:Selenium / Q000494:pharmacology*; D051140:Selenoproteins; D016415:Sequence Alignment; D014158:Transcription, Genetic / Q000187:drug effects*; D000097564:Iodothyronine Deiodinase Type II
D015124:8-Bromo Cyclic Adenosine Monophosphate; D005576:Colforsin; D003513:Cycloheximide; D018076:DNA, Complementary; D003609:Dactinomycin; D007453:Iodide Peroxidase; D007527:Isoenzymes; D011506:Proteins; D012333:RNA, Messenger; D012643:Selenium; D051140:Selenoproteins; D000097564:Iodothyronine Deiodinase Type II