12 directly interacts with PP2A: Evidence for Gα12-stimulated PP2A phosphatase activity and dephosphorylation of microtubule-associated protein, tau

Deguang Zhu, Kenneth S. Kosik, Thomas E. Meigs, Vijay Yanamadala, Bradley M. Denker

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


The Gα12/13 family of heterotrimeric G proteins modulate multiple cellular processes including regulation of the actin cytoskeleton. Gα12/13 interact with several cytoskeletal/scaffolding proteins, and in a yeast two-hybrid screen with Gα12, we detected an interaction with the scaffolding subunit (Aα) of the Ser/Thr phosphatase, protein phosphatase 2A (PP2A). PP2A dephosphorylates multiple substrates including tau, a microtubule-associated protein that is hyperphosphorylated in neurofibrilary tangles. The interaction of Aα and Gα12 was confirmed by coimmunoprecipitation studies in transfected COS cells and by glutathione S-transferase (GST)- Gα12 pull-downs from, cell lysates of primary neurons. The interaction was specific for Aα and Gα12 and was independent of Gα12 conformation. Endogenous Aα and Gα12 colocalized by immunofluorescent microscopy in Caco-2 cells and in neurons. In vitro reconstitution of GST-Gα12 or recombinant Gα12 with PP2A core enzyme resulted in ∼300% stimulation of PP2A activity that was not detected with other Gα subunits and was similar with GTPγS- and GDP-liganded Gα12. When tau and active kinase (Cdk5 and p25) were cotransfected in to COS cells, there was robust tau phosphorylation. Co-expression of wild type or QLα12 with tau and the active kinase resulted in 60 ± 15% reductions in tau phosphorylation. In primary cortical neurons stimulated with lysophosphatitic acid, a 50% decrease in tau phosphorylation was observed. The Gα12 effect on tau phosphorylation was inhibited by the PP2A inhibitor, okadaic acid (50 nM), in COS cells and neurons. Taken together, these findings reveal novel, direct regulation of PP2A activity by Gα12 and potential in vivo modulation of PP2A target proteins including tau.

Original languageEnglish (US)
Pages (from-to)54983-54986
Number of pages4
JournalJournal of Biological Chemistry
Issue number53
StatePublished - Dec 31 2004
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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