Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Arachidonic Acid / metabolism
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Butadienes / pharmacology
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CHO Cells
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Cricetinae
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Cricetulus
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Cytosol / enzymology
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Enzyme Activation
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Enzyme Inhibitors / pharmacology
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GTP-Binding Protein alpha Subunits, G12-G13 / genetics
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GTP-Binding Protein alpha Subunits, G12-G13 / metabolism*
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Group IV Phospholipases A2
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Imidazoles / pharmacology
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Marine Toxins
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Mitogen-Activated Protein Kinase 1 / antagonists & inhibitors
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3 / antagonists & inhibitors
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Mitogen-Activated Protein Kinase 3 / metabolism
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Mitogen-Activated Protein Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / metabolism*
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Mutation / genetics
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Nitriles / pharmacology
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Oxazoles / pharmacology
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Phospholipases A / antagonists & inhibitors
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Phospholipases A / metabolism*
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Phosphoric Monoester Hydrolases / antagonists & inhibitors
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Phosphoric Monoester Hydrolases / metabolism
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Phosphorylation
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Pyridines / pharmacology
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Pyrrolidines / pharmacology
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Transfection
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rhoA GTP-Binding Protein / metabolism
Substances
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Butadienes
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Enzyme Inhibitors
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Imidazoles
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Marine Toxins
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Nitriles
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Oxazoles
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Pyridines
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Pyrrolidines
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U 0126
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pyrrophenone
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Arachidonic Acid
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calyculin A
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases
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Phospholipases A
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Group IV Phospholipases A2
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Phosphoric Monoester Hydrolases
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GTP-Binding Protein alpha Subunits, G12-G13
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rhoA GTP-Binding Protein
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SB 203580