Phosphatidylcholine-specific phospholipase C and RhoA are involved in the thyrotropin-induced activation of phospholipase D in FRTL-5 thyroid cells.
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.
Kim
Jong-Hoon
JH
Institute of Biomedical Science and Department of Biochemistry, College of Medicine, Hanyang University, Seoul, Korea.
Kim
Sang Woo
SW
Jung
Pa Jong
PJ
Yon
Changsuek
C
Kim
Sang-Chul
SC
Han
Joong-Soo
JS
D036002:ADP Ribose Transferases / Q000378:metabolism; D000818:Animals; D001905:Botulinum Toxins / Q000378:metabolism; D001952:Bridged-Ring Compounds / Q000494:pharmacology; D002460:Cell Line; D004075:Diglycerides / Q000378:metabolism; D009636:Norbornanes; D010713:Phosphatidylcholines / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology; D013961:Thyroid Gland / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
D001952:Bridged-Ring Compounds; D004075:Diglycerides; D009636:Norbornanes; D010713:Phosphatidylcholines; D013859:Thiocarbamates; D013871:Thiones; C046498:tricyclodecane-9-yl-xanthogenate; D013972:Thyrotropin; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D011493:Protein Kinase C; D010738:Type C Phospholipases; D010739:Phospholipase D; D001905:Botulinum Toxins; D020742:rhoA GTP-Binding Protein