Regulation of LH receptor and PGF2alpha receptor signaling by the regulator of G protein signaling 2 (RGS2) in human and mouse granulosa cells.
Regulators of G protein signaling (RGS) proteins bind the G protein Galpha subunit in its active GTP-bound state and accelerate its GTPase activity, thus halting Galpha activity. Induction of RGS2 expression has been previously shown in the rat ovary in response to ovulatory stimulation; however, the significance of RGS2 in the ovary has not been established. This study reports the potential role of RGS2 in the signaling of two G protein-coupled receptors, the LH and PGF2alpha (FP) receptors, in the human and the mouse granulosa cell lines, KGN and NT-1. The RGS2 mRNA concentration was rapidly and transiently elevated by human chorionic gonadotropin (hCG) or PGF2alpha analogue cloprostenol and this was followed by a decline to basal level at 24 h. Expression of the downstream critical target gene of the LH and FP receptor signaling pathways, namely, cyclooxygenase 2 (COX2), was induced by hCG but was inhibited by cloprostenol. Overexpression of RGS2 attenuated hCG-induced COX2 transcription. However, this augmented cloprostenol-mediated suppression of COX2 transcription. Confocal microscopy and immunoblot analysis were adopted to monitor the intracellular localization of RGS2 in COS-7 cells carrying the FP receptor and expressing RGS2-GFP or FLAG-RGS2. RGS2 was initially located predominantly in the nucleus and activation of the FP receptor resulted in RGS2 translocation from nucleus to the cell membrane. Thus, RGS2 expression was upregulated by LH receptor and FP receptor activation and modulation of partner receptor signaling by RGS2 may require RGS2 translocation from the nucleus to the plasma membrane.
Wu
Yuh-Lin
YL
Department of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China. ylwu@ym.edu.tw
Chuang
Hsiang-Hao
HH
Kou
Yu Ru
YR
Lee
Tzong-Shyuan
TS
Lu
Shing-Hwa
SH
Huang
Yu-Chu
YC
Nishi
Yoshihiro
Y
Yanase
Toshihiko
T
D000818:Animals; D002460:Cell Line; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D003008:Cloprostenol / Q000494:pharmacology; D005260:Female; D006107:Granulosa Cells / Q000502:physiology*; D006801:Humans; D051379:Mice; D020710:RGS Proteins / Q000502:physiology*; D011974:Receptors, LH / Q000502:physiology*; D011982:Receptors, Prostaglandin / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
D006063:Chorionic Gonadotropin; D020710:RGS Proteins; C087182:RGS2 protein, human; D011974:Receptors, LH; D011982:Receptors, Prostaglandin; C105345:Rgs2 protein, mouse; C034671:prostaglandin F2alpha receptor; D003008:Cloprostenol