Post-transcriptional regulation of the gonadotropin-releasing hormone gene in GT1-7 cells.
GT1-7 cells respond to treatment with the phorbol ester, phorbol 12-myristate 13-acetate (PMA), with an inhibition of transcription of the proGnRH gene and decreases in GnRH mRNA levels. However, the timing of this decrease in GnRH mRNA levels suggests that a decrease in GnRH mRNA stability may be involved in addition to an inhibition of transcription of the proGnRH gene. To address this possibility, we treated GT1-7 cells with 100 nM PMA for 4 h and then monitored GnRH mRNA levels over time after blockade of GnRH gene transcription with DRB. PMA treatment caused GnRH mRNA half-life to decrease from 30 to 11 h. Then, to verify this observation, we examined changes in GnRH mRNA poly (A) tail length, which may be a reflection of mRNA turnover, following treatment of GT1-7 cells with PMA or vehicle for 0, 4, 8 or 24 h. The poly (A) tail was removed from half of the GT1 cytoplasmic RNA sample by digestion with RNase H and the difference in GnRH mRNA size with and without RNase H treatment was determined by Northern hybridization. PMA treatment (4 and 8 h) resulted in a significant decrease in the length of the GnRH mRNA poly (A) tail, consistent with a decrease in GnRH mRNA stability. This finding suggests that GnRH mRNA turnover is inducible by substances such as PMA. Our study indicates that a change in mRNA stability is one of a multiplicity of levels at which GnRH gene expression is regulated.
Gore
A C
AC
Fishberg Research Center for Neurobiology, Mount Sinai School of Medicine, New York, NY 10029, USA.
Yeo
T T
TT
Ho
A
A
Roberts
J L
JL
D015152:Blotting, Northern; D002460:Cell Line; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics*; D006207:Half-Life; D011061:Poly A / Q000032:analysis; D012333:RNA, Messenger / Q000378:metabolism; D016914:Ribonuclease H / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects
D012333:RNA, Messenger; D011061:Poly A; D007987:Gonadotropin-Releasing Hormone; D016914:Ribonuclease H; D013755:Tetradecanoylphorbol Acetate