Kim Jong-Hoon, Kim Sang Woo, Jung Pa Jong, Yon Changsuek, Kim Sang-Chul, Han Joong-Soo
Institute of Biomedical Science and Department of Biochemistry, College of Medicine, Hanyang University, Seoul, Korea.
Mol Cells. 2002 Oct 31;14(2):272-80.
We investigated the possible involvement of phosphatidylcholine-specific phospholipase C (PC-PLC) in the thyroid-stimulating hormone (TSH)-induced protein kinase C (PKC)/phospholipase D (PLD) activation in FRTL-5 thyroid cells. Treatment of TSH resulted in both dose- and time-dependent increases in PLD activity. TSH induced translocations of PKCalpha and RhoA from the cytosol to the membrane within 30 min. TSH also stimulated diacylglycerol (DAG)/phosphorylcholine (PhoCho) production via PC-PLC. Pretreatment of the cells with D609, a potent inhibitor of PC-PLC, effectively inhibited the translocation of PKCalpha from the cytosol to the membrane and significantly decreased TSH-induced PLD activation. Moreover, C3 transferase, an inhibitor of RhoA, significantly inhibited PLD activity that was stimulated by TSH, which suggests that RhoA is also involved in TSH-induced PLD activation. As we expected, pretreatment of the cells with both C3 transferase and D609 completely inhibited the TSH-induced PLD activity. These findings suggest that DAG that is produced from cellular PC through PC-PLC plays an essential role in the TSH-induced PKC/PLD activation. Also, RhoA and PKCalpha are involved in the regulation of TSH-induced PLD activation in FRTL-5 thyroid cells.
我们研究了磷脂酰胆碱特异性磷脂酶C（PC-PLC）在促甲状腺激素（TSH）诱导的FRTL-5甲状腺细胞蛋白激酶C（PKC）/磷脂酶D（PLD）激活过程中可能发挥的作用。TSH处理导致PLD活性呈剂量和时间依赖性增加。TSH在30分钟内诱导PKCα和RhoA从胞质溶胶转位至细胞膜。TSH还通过PC-PLC刺激二酰基甘油（DAG）/磷酸胆碱（PhoCho）的产生。用PC-PLC的强效抑制剂D609预处理细胞，可有效抑制PKCα从胞质溶胶到细胞膜的转位，并显著降低TSH诱导的PLD激活。此外，RhoA抑制剂C3转移酶显著抑制TSH刺激的PLD活性，这表明RhoA也参与TSH诱导的PLD激活。正如我们所预期的，用C3转移酶和D609同时预处理细胞可完全抑制TSH诱导的PLD活性。这些发现表明，通过PC-PLC从细胞磷脂酰胆碱产生的DAG在TSH诱导的PKC/PLD激活中起重要作用。此外，RhoA和PKCα参与FRTL-5甲状腺细胞中TSH诱导的PLD激活的调节。
