J Korean Soc Endocrinol.
2002 Aug;17(4):465-472.
Effect of TRH on Phospholipase D Activity in GH3 Cell
- Affiliations
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- 1Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea.
- 2Department of Biochemistry, Hanyang University College of Medicine, Seoul, Korea.
Abstract
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BACKGROUND: GH3 cells are a well characterized and widely used model used for the in vitro study of growth hormone (GH) secretion. Thyrotropin releasing hormone (TRH) binds to receptors belonging to the family of G protein-coupled receptors, and secrets both GH & prolactin. Phospholipase D (PLD) is an enzyme that hydrolyses phosphatidylcholine to yield phosphatidic acid and choline, and plays important roles in cellular proliferation and hormonal secretion. To elucidate the pathway of the action of TRH in GH3 cells, we investigated the activities of PLC and PLD in GH3 cells treated with TRH or phorbor 12-myristate 13-acetate (PMA).
METHODS
GH3 cells were labeled with [3H] myristate, followed by incubation of with 0.3% ethanol, prior to before the addition of the agonists. The total lipids were extracted from the harvested cells following treatment with the agonists. The PLD activity was assessed by measuring [3H] phosphatidylethanol from the [3H] phospholipid using thin layer chromatography.
RESULTS
TRH (1 muM) stimulated the PLC activity by 44-fold over that of the control values. TRH (1 microM), mastoparan (5 muM), and PMA (500 muM) for 30 minutes increased PLD activity by 1.9, 1.5 and 2.2 fold, respectively, in comparison to the controls. The PLD activities after 15, 30, 60, 120 and 240 min treatments of TRH (1 microM) were 142%, 170%, 172%, 160% and 115%, respectively.
CONCLUSION
These results suggest that TRH stimulates not only the PLC activity, but also the PLD activity in GH3 cells.
MeSH Terms
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Cell Proliferation
Choline
Chromatography, Thin Layer
Ethanol
Growth Hormone
Humans
Myristic Acid
Phosphatidic Acids
Phosphatidylcholines
Phospholipase D*
Phospholipases*
Prolactin
Thyrotropin-Releasing Hormone
Choline
Ethanol
Growth Hormone
Myristic Acid
Phosphatidic Acids
Phosphatidylcholines
Phospholipase D
Phospholipases
Prolactin
Thyrotropin-Releasing Hormone
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