Thyrotropin-releasing hormone increases phospholipase D activity through stimulation of protein kinase C in GH3 cells

被引:0
|
作者
Kim, DS
Yoon, MS
Kim, TW
Han, JS
机构
[1] Hanyang Univ, Coll Med, Dept Internal Med, Seoul 133791, South Korea
[2] Hanyang Univ, Coll Med, Dept Biochem, Seoul 133791, South Korea
关键词
thyrotropin-releasing hormone (TRH); phospholipase D (PLD); protein kinase C (PKC); GH(3) cell;
D O I
10.1385/ENDO:23:1:33
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Activation of phospholipase D was investigated after treatment of GH(3) cells with thyrotropin-releasing hormone. Thyrotropin-releasing hormone treatment resulted in both time- and dose-dependent increases of phospholipase D activity, translocation of protein kinase C-alpha and -betal isozymes from cytosol to membrane within 30 min, and approx 43-fold increase of phosphatidylinositol-specific phospholipase C activity. Intracellular calcium concentration was rapidly increased and diacyglycerol level remained high up to 3 h after the treatment. Pretreatment of the cells with U73122, a potent inhibitor of phosphatidylinositol-specific phospholipase C, inhibited thyrotropin-releasing hormone-induced phospholipase D activation. Protein kinase C activity was down-regulated by pretreatment of the GH(3)cells with either protein kinase C inhibitors (RO320432, GF109203X) or preincubation of the cells with phorbol myristrate acetate (500 nM) for 24 h. This treatment largely abolished the thyrotropin-releasing hormone-induced activation of phospholipase D, thus further confirming the involvement of protein kinase C in the activation. These results suggest that thyrotropin-releasing hormone-induced phospholipase D activation may be due to phosphatidyl inositol-specific phospholipase C, and activation of protein kinase C isozymes is responsible for this stimulation.
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页码:33 / 38
页数:6
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