Dissociation between release and gene expression of gonadotropin alpha-subunit in gonadotropin-releasing hormone-stimulated alpha T3-1 cell line.
The alpha T3-1 cell line which was derived by targeted tumorigenesis in transgenic mice [Windle et al. (1990) Mol. Endocrinol. 4, 597-603] possesses high-affinity binding sites for GnRH analogs coupled to enhanced phosphoinositide turnover and phospholipase D activity. Incubation of alpha T3-1 cells with [D-Trp6]-GnRH analog (GnRH-A) resulted in a rapid increase in gonadotropin alpha-subunit mRNA levels which was detected already at 30 min of incubation (0.1 nM GnRH-A, 3-fold, p < 0.01). The effect diminished with time to reach basal levels at about 12 h of incubation, with a secondary rise in alpha mRNA levels between 12 and 24 h of incubation. Addition of the protein kinase C activator 12-O-tetradecanoylphorbol 13-acetate (TPA, 100 ng/mL) or the Ca2+ ionophore ionomycin (1 microM) to alpha T3-1 cells also resulted in a rapid increase in alpha-subunit mRNA levels. Surprisingly, GnRH-induced alpha-subunit release was detected only after a lag of 4 h of incubation. Thus, dissociation between exocytosis and gene expression can be demonstrated in GnRH-stimulated alpha T3-1 cell line.
D000818:Animals; D015152:Blotting, Northern; D002064:Buserelin / Q000378:metabolism; D015870:Gene Expression; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D010716:Phosphatidylinositols / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011966:Receptors, LHRH / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D017329:Triptorelin Pamoate / Q000031:analogs & derivatives*; D014407:Tumor Cells, Cultured
D015292:Glycoprotein Hormones, alpha Subunit; D010716:Phosphatidylinositols; D012333:RNA, Messenger; D011966:Receptors, LHRH; D017329:Triptorelin Pamoate; D007987:Gonadotropin-Releasing Hormone; D015759:Ionomycin; C019176:Tryptal; D013755:Tetradecanoylphorbol Acetate; D002064:Buserelin