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HOMOLOGOUS UP-REGULATION OF THE GONADOTROPIN-RELEASING HORMONE RECEPTOR IN A T3-1 CELLS IS ASSOCIATED WITH UNCHANGED RECEPTOR MESSENGER RNA (MRNA) LEVELS AND ALTERED MRNA ACTIVITY
Citation:
Tsutsumi, M., S. Laws, AND S. Sealfon. HOMOLOGOUS UP-REGULATION OF THE GONADOTROPIN-RELEASING HORMONE RECEPTOR IN A T3-1 CELLS IS ASSOCIATED WITH UNCHANGED RECEPTOR MESSENGER RNA (MRNA) LEVELS AND ALTERED MRNA ACTIVITY. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/324 (NTIS PB94197126), 1993.
Description:
Depending on the concentration and duration of agonist exposure, gonadotropin-releasing hormone (GnRH) receptor number either increases or decreases in response to GnRH. he molecular basis of this regulation could involve a combination of modulation of gene transcription, RNA processing, translation, or degradation. o investigate the underlying mechanisms, the homologous regulation of GnRH receptor binding, mRNA levels and mRNA activity was studied in the mouse gonadotrope cell line T3-1 cells. nRH-A radioligand binding assay results show that treatment of T3-1 cells with 1uM GnRH for 24 hr induced a significant reduction in the number of GnRH receptors. espite the decrease in receptor number, cytosylic and total GnRH receptor mRNA levels were not significantly altered. imilarly, increases in GnRH receptor number induced by 20 min. exposure to nM concentrations of GNRH were associated with unchanged levels of receptor MRNA. ocytes injected with RNA-isolated from cells treated with nM GnRH showed a diminished GnRH-induced response compared to oocytes injected with RNA fromcontrol cells. ocytes injected with RNA isolated from cells treated with nM concentrations of GNRH showed a nearly two-fold increase in response compared with control RNA-injected cells. hese data suggest that homologous regulation of the GnRH receptor is under post-transcriptional control and due to modulation of thecapacity of cellular RNA to direct the synthesis of GnRH receptors.
