Galpha13 mediates activation of the cytosolic phospholipase A2alpha through fine regulation of ERK phosphorylation.
Heterotrimeric GTP-binding (G) proteins transduce hormone-induced signals to their effector enzymes, which include several phospholipases. In particular, the G(o)/G(i) and G(q) protein families have been shown to couple signaling to phospholipase A(2) (PLA(2)), phospholipase C, and phospholipase D, while the G(12)/G(13) family has been linked to the activation of small GTPases of the Rho family, and hence, to phospholipase D activation. Here, we demonstrate that in CHO cells, the G(12)/G(13) family is also able to activate cPLA(2)alpha, through the activation of RhoA and, subsequently, ERK1/2. Hormone-induced arachidonic acid release increased as a consequence of Galpha(13) overexpression, and was inhibited through inhibition of Galpha(13) signaling. The Galpha(13)-mediated cPLA(2)alpha activation was inhibited by pharmacological blockade of ERK1/2 with either U0126 or PD98059, and by RhoA inactivation with C3 toxin or a dominant-negative RhoA (N19RhoA), and was stimulated by the serine-threonine phosphatase inhibitor calyculin A. Our data thus identify a pathway of cPLA(2)alpha regulation that is initiated by thrombin and purinergic receptor activation, and that signals through Galpha(13), RhoA and ERK1/2, with the involvement of a calyculin-sensitive phosphatase.
Mariggiò
Stefania
S
Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Via Nazionale, 66030 Santa Maria Imbaro, Chieti, Italy.
Bavec
Aljosa
A
Natale
Elena
E
Zizza
Pasquale
P
Salmona
Mario
M
Corda
Daniela
D
Di Girolamo
Maria
M
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D002070:Butadienes / Q000494:pharmacology; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000235:genetics / Q000378:metabolism*; D054513:Group IV Phospholipases A2; D007093:Imidazoles / Q000494:pharmacology; D008387:Marine Toxins; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009570:Nitriles / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D014162:Transfection; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D002070:Butadienes; D004791:Enzyme Inhibitors; D007093:Imidazoles; D008387:Marine Toxins; D009570:Nitriles; D010080:Oxazoles; D011725:Pyridines; D011759:Pyrrolidines; C113580:U 0126; C455981:pyrrophenone; D016718:Arachidonic Acid; C059041:calyculin A; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010741:Phospholipases A; D054513:Group IV Phospholipases A2; D010744:Phosphoric Monoester Hydrolases; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020742:rhoA GTP-Binding Protein; C093642:SB 203580