Dexamethasone inhibits growth factor-induced type 3 deiodinase activity and mRNA expression in a cultured cell line derived from rat neonatal brown fat vascular-stromal cells.
Studies examining the regulation of the type 3 deiodinase (D3) have been hampered by the lack of cell lines that constitutively express this enzyme. To address this issue, a new cell line, designated brown fat vascular-stromal (BVS-1), was generated by continuous subculturing of precursor cells derived from the vascular-stromal fraction of rat neonatal brown fat. BVS-1 cells did not differentiate into adipocytes when cultured for 5 d in DMEM supplemented with 2% newborn calf serum, 4 nM insulin, 2 nM T(3), and 10 nM dexamethasone (DEX). However, when cultured in regular medium, the cells expressed high levels of D3 activity (1-5 pmol/h per milligram protein) and mRNA. D3 mRNA was markedly induced by treatment for 6 h with epidermal growth factor, acid or basic fibroblast growth factors (10 ng/ml), or a 3-h treatment with a phorbol ester [12-O-tetradecanoylphorbol-13-acetate (TPA), 1 microM] or 10% fetal bovine serum. However, preincubation of cells overnight with 50 nM DEX completely blocked the D3-inducing effects of basic fibroblast growth factor. The DEX effect was partially blocked when a glucocorticoid receptor antagonist was present. Overnight DEX treatment (50 nM) also decreased basal D3 activity by 80%. In summary, we have established BVS-1 cells as a continuous cell line useful for studying the regulation of D3 expression. Furthermore, we have shown that DEX inhibits growth factor-induced D3 expression in these cells.
Hernandez
Arturo
A
Department of Medicine, Dartmouth Medical School, Lebanon, New Hampshire 03756, USA.
St  Germain
Donald L
DL
D002001:Adipose Tissue, Brown / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D000831:Animals, Newborn; D001808:Blood Vessels / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology*; D007453:Iodide Peroxidase / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017154:Stromal Cells / Q000187:drug effects / Q000201:enzymology*
D006133:Growth Substances; D012333:RNA, Messenger; D003907:Dexamethasone; C117274:iodothyronine deiodinase type III; D007453:Iodide Peroxidase