山梨医科大学雑誌 第11巻3号 053-058(1996)

Thyrotropin Regulates the Expression of mRNA for G-protein
α-Subunits (αs and αi2) in FRTL-5 Cells

Xiao-ding PENG, Kazutaka HARAGUCHI, Toyoshi ENDO, and Toshimasa ONAYA

Abstract: In order to determine the molecular mechanism of regulation of the GTP-binding protein (G-protein)-adenylyl cyclase system by thyrotropin (TSH), we examined the expression of mRNA for G-protein stimulatory α subunit (αs) and inhibitory α subunit (αi2) by the reverse transcription-polymerase chain reaction (RT-PCR) method. TSH (10 mU/ml) stimulated the expression of αs mRNA in FRTL-5 cells by 40% after 6 hr, which was gradually reduced to a normallevel by 24 hr. Expression of β-actin mRNA was unchanged. In contrast, expression of αi2 mRNA was reduced by 25% after 6 hr and returned to the normal level by 24 hr. This concomitant change increased the relative abundance of αs to αi2. The effect of TSH on the expression of αs mRNA was mimicked by dibutyryl cAMP and forskolin. These findings show that the expression of G-protein subunits is regulated by TSH via a cAMP-dependent pathway on the mRNA level.

Key words: Thyrotropin, G-protein, αs, αi, FRTL-5 Cell




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