G-protein-coupled receptor stimulation of the p42/p44 mitogen-activated protein kinase pathway is attenuated by liPID phosphate phosphatases 1, 1a, and 2 in human embryonic kidney 293 cells

Forbes Alderton, Peter Darroch, Balwinder Sambi, Amanda McKie, Ikhlas Said Ahmed, Nigel Pyne, Susan Pyne

Research output: Contribution to journalArticlepeer-review

80 Citations (Scopus)

Abstract

Sphingosine 1-phosphate, lysophosphatidic acid, and phosphatidic acid bind to G-protein-coupled receptors to stimulate intracellular signaling in mammalian cells. Lipid phosphate phosphatases (1, 1a, 2, and 3) are a group of enzymes that catalyze de-phosphorylation of these lipid agonists. It has been proposed that the lipid phosphate phosphatases exhibit ecto activity that may function to limit bioavailability of these lipid agonists at their receptors. In this study, we show that the stimulation of the p42/p44 mitogen-activated protein kinase pathway by sphingosine 1-phosphate, lysophosphatidic acid, and phosphatidic acid, all of which bind to Gi/o-coupled receptors, is substantially reduced in human embyronic kidney 293 cells transfected with lipid phosphate phosphatases 1, 1a, and 2 but not 3. This was correlated with reduced basal intracellular phosphatidic acid and not ecto lipid phosphate phosphatase activity. These findings were supported by results showing that lipid phosphate phosphatases 1, 1a, and 2 also abrogate the stimulation of p42/p44 mitogen-activated protein kinase by thrombin, a peptide Gi/o-coupled receptor agonist whose bioavailability at its receptor is not subject to regulation by the phosphatases. Furthermore, the lipid phosphate phosphatases have no effect on the stimulation of p42/p44 mitogen-activated protein kinase by other agents that do not use G-proteins to signal, such as serum factors and phorbol ester. Therefore, these findings show that the lipid phosphate phosphatases 1, 1a, and 2 may function to perturb G-protein-coupled receptor signaling per se rather than limiting bioavailability of lipid agonists at their respective receptors.
Original languageEnglish
Pages (from-to)13452-13460
Number of pages9
JournalJournal of Biological Chemistry
Volume276
DOIs
Publication statusPublished - 2001

Keywords

  • kidney cells
  • receptor stimulation
  • bioavailability
  • intracellular signaling

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