Thyrotrophin, forskolin and ionomycin increase cathepsin B mRNA concentrations in rat thyroid cells in culture.
In order to study the regulation of cathepsin B expression in the thyroid, cathepsin B mRNA concentrations were measured in rat thyroid cells (FRTL5) in culture. Northern blot analysis demonstrated that cathepsin B mRNA concentrations were increased in FRTL5 cells cultured for up to 6 days in TSH. The effect of TSH on cathepsin B mRNA concentrations was dose dependent over the range 25-150 mu units/ml. Cytoplasmic dot-blot analysis was used to characterize this effect further. The TSH-induced increase in cathepsin B mRNA concentrations (approximately fivefold over that in untreated cells) was partially mimicked by forskolin (approximately threefold) and ionomycin, while phorbol ester decreased cathepsin B mRNA concentrations. Similar changes were observed for thyroglobulin and actin mRNA concentrations. TSH had no effect on cathepsin B enzymatic activity or immunoreactive protein concentration. These results demonstrate (1) that cathepsin B expression in the thyroid is regulated in parallel with that of thyroglobulin and actin, and (2) that cyclic AMP- and Ca2+-dependent processes stimulate gene expression, while phorbol ester treatment inhibits gene expression in FRTL5 cells.
Phillips
I D
ID
Department of Medicine, University of Birmingham, Queen Elizabeth Hospital.
Black
E G
EG
Sheppard
M C
MC
Docherty
K
K
D000199:Actins / Q000096:biosynthesis; D000818:Animals; D002401:Cathepsin B / Q000096:biosynthesis* / Q000235:genetics; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D004987:Ethers / Q000494:pharmacology; D015759:Ionomycin; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013954:Thyroglobulin / Q000096:biosynthesis; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D013972:Thyrotropin / Q000494:pharmacology*
D000199:Actins; D004987:Ethers; D012333:RNA, Messenger; D005576:Colforsin; D015759:Ionomycin; D013972:Thyrotropin; D013954:Thyroglobulin; D002401:Cathepsin B; D013755:Tetradecanoylphorbol Acetate