Epidermal growth factor induces prolactin mRNA in GH4C1 cells via a protein synthesis-dependent pathway.
Prolactin (PRL) gene expression is regulated through a complex network of signal transduction pathways activated by various hormones and growth factors. Estrogens regulate PRL gene transcription in vivo through both direct and indirect, protein synthesis-dependent, mechanisms. Therefore, we hypothesized that other stimulators of PRL gene transcription might also act via protein synthesis-dependent mechanisms. To test this hypothesis, we examined, in GH4C1 rat pituitary tumor cells, the effects of protein synthesis inhibitors on the induction of PRL mRNA by known stimulators of PRL gene transcription. Whereas induction by epidermal growth factor (EGF) was abolished by cycloheximide and puromycin, increases in PRL mRNA caused by thyrotropin releasing hormone, 12-O-tetradecanoylphorbol 13-acetate, forskolin, or dibutyryl cyclic AMP were unaffected. These data suggest that the induction of PRL mRNA by EGF may require the induced synthesis of an intermediary regulatory protein.
Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha 68198-6805.
C A
CA
Gilchrist
J D
JD
Shull
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism; D011388:Prolactin / Q000096:biosynthesis*; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D011506:Proteins / Q000502:physiology; D011691:Puromycin / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D011500:Protein Synthesis Inhibitors; D011506:Proteins; D012333:RNA, Messenger; D005576:Colforsin; D011691:Puromycin; D013973:Thyrotropin-Releasing Hormone; D004815:Epidermal Growth Factor; D003994:Bucladesine; D011388:Prolactin; D003513:Cycloheximide; D013755:Tetradecanoylphorbol Acetate