Lysophosphatidic acid activation of phosphatidylcholine-hydrolysing phospholipase D and actin polymerization by a pertussis toxin-sensitive mechanism.
Incubation of IIC9 fibroblasts with lysophosphatidic acid (LPA) induced an increase in the amount of filamentous actin (F-actin), which was concentration-dependent with a maximal effect at 100 ng/ml. Phosphatidic acid (PA) also produced a concentration-dependent increase of F-actin, but it was less potent than LPA. The LPA-induced increase in F-actin was rapid and sustained for at least 60 min. LPA rapidly increased the levels of PA and choline, with maximal increases at 5 min and 30 s respectively. LPA also caused a monophasic increase in diacylglycerol (DAG) which lagged behind the increases in PA and choline. LPA stimulated phosphatidylbutanol formation in the presence of butanol and produced a small increase in inositol phosphates that was much less than that induced by alpha-thrombin. Pretreatment of cells with pertussis toxin (PTX) caused greater than 50% inhibition of the LPA-stimulated increases in PA, DAG and choline. PTX increased the LPA concentration required to induce half-maximal actin polymerization by about 10-fold. PTX caused a similar shift in the dose-response curve for LPA-induced PA formation. These results suggest that LPA induces an increase in PA by activating a phosphatidylcholine-hydrolysing phospholipase D via a PTX-sensitive G-protein and that the increase in PA is involved in the activation of actin polymerization.
Ha
K S
KS
Howard Hughes Medical Institute, Nashville, TN.
Yeo
E J
EJ
Exton
J H
JH
D000199:Actins / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002794:Choline / Q000378:metabolism; D002999:Clone Cells; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005347:Fibroblasts; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D008246:Lysophospholipids / Q000494:pharmacology*; D037342:Pertussis Toxin; D010712:Phosphatidic Acids / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D013997:Time Factors; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D000199:Actins; D007295:Inositol Phosphates; D008246:Lysophospholipids; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D010739:Phospholipase D; D002794:Choline