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[Activin inhibits the promoter activity of human growth hormone gene in rat pituitary GH3 cells.] [Ariticle in Chinese]

GONG Feng-Ying, DENG Jie-Ying, ZHU Hui-Juan, PAN Hui

Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences &； Peking Union Medical College, Beijing 100730, China

Abstract

The present study was aimed at investigating the effect of activin on the activity of human growth hormone (hGH) genepromoter in rat pituitary GH3 cells and the underlying molecular mechanism. The method of luciferase reporter gene was used. Wefirstly established a stable GH3 cell line which contains hGH gene promoter (-484 to 30 bp) and luciferase reporter gene by transfectingpGL3-484-Luc2 luciferase expression plasmid into GH3 cells using Lipofectamine transfection reagent. After treating these cells withactivin or activin plus various signaling transduction activators, the concentration of GH in the medium and lysate of GH3 cells andluciferase activities in GH3 cells were measured. The results showed that activin (5 nmol/L, 50 nmol/L) decreased the secretion andsynthesis of GH. The amounts of GH content in GH3 lysate and medium treated with 50 nmol/L activin were 82% and 59% of thecontrol, respectively. Furthermore, activin (5, 50 nmol/L) reduced the luciferase expression in stable GH3 cells, with the expressionbeing 77% and 69% of the control (P<0.001). Among the activators of intracellular signaling transduction pathways, mitogen-activatedprotein kinases kinase (MAPKK/MEK) activators C6 ceramide (1 μmol/L) abolished completely the inhibitory effect of activin.Western blot analysis further confirmed the inhibition of phosphorylated MEK in GH3 cells. The inhibitory effect of activin wasabrogated following the deletion of the fragment from -132 to -66 bp within the hGH gene promoter. These results indicate that activindecreases the activity of hGH gene promoter in rat pituitary GH3 cells. The intracellular MEK dependent signaling pathway and thepromoter sequence that spans the -132 to -66 bp fragment of hGH gene are involved in the inhibitory effect of activin.

Key words: activin; growth hormone; promoter; GH3 cells; MAPKK/MEK

Received: 2009-10-23　　Accepted: 2010-01-06

Corresponding author: 龚凤英　　E-mail: fygong5074@yahoo.com.cn

Citing This Article：

GONG Feng-Ying, DENG Jie-Ying, ZHU Hui-Juan, PAN Hui. [Activin inhibits the promoter activity of human growth hormone gene in rat pituitary GH3 cells.] [Ariticle in Chinese] . Acta Physiol Sin 2010; 62 (1): 49-54 (in Chinese with English abstract).