Increased expression of acidic ribosomal protein (P0) mRNA after phorbol ester treatment of cultured rat thyroid (FRTL-5) cells.
P0, an acidic protein component of the ribosomal protein in eukaryotic 60 S ribosomal subunit, plays an important role in polypeptide chain elongation during translation. To investigate the role of protein kinase C in thyroid cell protein synthesis, we examined the effect of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) on the expression of P0 mRNA and protein. RNA slot blot hybridization revealed that TPA induced the accumulation of P0 mRNA in FRTL-5 cells in a time- and dose-dependent manner. A maximal increase of 2-fold was observed 18 h after addition of TPA. Cycloheximide markedly inhibited the TPA-induced accumulation of P0 mRNA. Nuclear runoff transcription assays using nuclei prepared from TPA-treated FRTL-5 cells revealed that TPA increased the transcription of P0 mRNA but not of beta-actin. Immunoblotting experiments using anti-P protein antibody showed that TPA also increased the protein amount of P0. These results suggest that TPA activates protein synthesis in thyroid cells by inducing the expression of ribosomal proteins.
Saito
T
T
Third Department of Internal Medicine, University of Yamanashi Medical School, Japan.
Ikeda
M
M
Endo
T
T
Tsurugi
K
K
Onaya
T
T
D000199:Actins / Q000235:genetics; D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects*; D007700:Kinetics; D010750:Phosphoproteins / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D012269:Ribosomal Proteins; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology
D000199:Actins; D010750:Phosphoproteins; D012333:RNA, Messenger; D012269:Ribosomal Proteins; C054675:ribosomal protein P0; D013972:Thyrotropin; D003513:Cycloheximide; D013755:Tetradecanoylphorbol Acetate