Pertussis toxin-sensitive heterotrimeric G(αi/o) proteins mediate WNT/β-catenin and WNT/ERK1/2 signaling in mouse primary microglia stimulated with purified WNT-3A

Cell Signal. 2013 Apr;25(4):822-8. doi: 10.1016/j.cellsig.2012.12.006. Epub 2012 Dec 22.


WNT-3A is a secreted lipoglycoprotein that engages Class Frizzled receptors and LDL receptor related protein 5/6 (LRP5/6) for cellular communication. Generally, WNT-3A mediates WNT/β-catenin signaling to regulate TCF/LEF-dependent gene expression. We have previously shown that β-catenin levels are elevated in proinflammatory microglia of Alzheimer's disease patients and that WNT-3A can evoke a strong proinflammatory response in primary microglia. In order to investigate the underlying mechanisms, we focus here on the pharmacological dissection of WNT-3A-induced signaling to β-catenin and to the extracellular signal-regulated kinases 1/2 (ERK1/2) in mouse primary microglia. Both pathways are induced by WNT-3A with slightly different kinetics, suggesting that they might be pharmacologically separable. Inhibition of heterotrimeric Gαi/o proteins by pertussis toxin blocks WNT-3A-induced LRP6 phosphorylation, disheveled shift, β-catenin stabilization and phosphorylation of ERK1/2. On the other hand LRP6 blockade by Dickkopf 1 treatment abrogated the WNT/β-catenin pathway without affecting WNT/ERK1/2 signaling. In the opposite way, inhibition of βγ subunits, phospholipase C (PLC), intracellular calcium and MEK1/2, the upstream kinase of ERK1/2, blocked ERK1/2 phosphorylation but not β-catenin stabilization. In summary, the data suggest a central role of Gαi/o for both β-catenin-dependent and -independent pathways. WNT-3A-induced ERK1/2 phosphorylation is mediated by βγ subunits, PLC, intracellular calcium and MEK1/2. Furthermore, we show that cyclooxygenase 2 (COX2), a generic proinflammatory marker of microglia, is induced by WNT-3A through ERK1/2-dependent pathways arguing that β-catenin-independent signaling downstream of WNT-3A is of physiological importance for the proinflammatory regulation of microglia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminoacetonitrile / analogs & derivatives
  • Aminoacetonitrile / pharmacology
  • Animals
  • Calcium / metabolism
  • Cells, Cultured
  • Cyclooxygenase 2 / metabolism
  • GTP-Binding Protein alpha Subunits, Gi-Go / antagonists & inhibitors
  • GTP-Binding Protein alpha Subunits, Gi-Go / metabolism*
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Intercellular Signaling Peptides and Proteins / pharmacology
  • Kinetics
  • Low Density Lipoprotein Receptor-Related Protein-6 / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Microglia / cytology
  • Microglia / drug effects*
  • Microglia / metabolism
  • Mitogen-Activated Protein Kinase 1 / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Pertussis Toxin / toxicity*
  • Phosphorylation
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / genetics
  • Recombinant Proteins / pharmacology
  • Signal Transduction / drug effects*
  • Type C Phospholipases / metabolism
  • Wnt Proteins / metabolism
  • Wnt3A Protein / isolation & purification
  • Wnt3A Protein / pharmacology*
  • beta Catenin / metabolism


  • Dkk1 protein, mouse
  • Intercellular Signaling Peptides and Proteins
  • Low Density Lipoprotein Receptor-Related Protein-6
  • Lrp6 protein, mouse
  • Recombinant Proteins
  • SL 327
  • Wnt Proteins
  • Wnt3A Protein
  • beta Catenin
  • Aminoacetonitrile
  • Cyclooxygenase 2
  • Pertussis Toxin
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Type C Phospholipases
  • GTP-Binding Protein alpha Subunits, Gi-Go
  • Calcium