Dual effects of PKNalpha and protein kinase C on phosphorylation of tau protein by glycogen synthase kinase-3beta

Biochem Biophys Res Commun. 2000 Jun 24;273(1):209-12. doi: 10.1006/bbrc.2000.2926.


We analyzed the effects of PKNalpha and protein kinase C (PKC) on phosphorylation of tau protein by glycogen synthase kinase (GSK)-3beta using monoclonal antibodies (AT8, AT180, and AT270). These antibodies are highly specific for phosphorylated tau in Alzheimer paired helical filaments, and recognize phosphorylated Ser202/Thr205, Thr231, and Thr181 of tau protein, respectively. Immunoblot analysis demonstrated that PKNalpha and PKC did not directly phosphorylate their sites, whereas GSK-3beta efficiently did so. Incubating GSK-3beta with PKNalpha or PKC subtypes inhibited subsequent GSK-3beta-induced AT8 and AT270 immunoreactivity. However, the constitutive active form of the GSK-3beta(S9A) mutant was almost totally inert to each enzyme. Incubating tau with PKNalpha increased the GSK-3beta-induced AT180 immunoreactivity, which was further enhanced when the S9A mutant was used instead of the wild type GSK-3beta. These results suggest that PKNalpha and PKC directly inhibit GSK-3beta activity at least in part by phosphorylating Ser9 of GSK-3beta, and that they indirectly suppress GSK-3beta-stimulated phosphorylation of tau at amino acids Ser202/Thr205 and Thr181, but enhanced phosphorylation at Thr231 through phosphorylation at other sites of tau.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal / immunology
  • Bacterial Proteins*
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors
  • Calcium-Calmodulin-Dependent Protein Kinases / genetics
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Epitopes / immunology
  • Glycogen Synthase Kinase 3
  • Glycogen Synthase Kinases
  • Humans
  • Molecular Sequence Data
  • Mutation / genetics
  • Phosphoproteins / chemistry
  • Phosphoproteins / immunology
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Phosphoserine / immunology
  • Phosphoserine / metabolism
  • Phosphotyrosine / immunology
  • Phosphotyrosine / metabolism
  • Protein Kinase C / chemistry
  • Protein Kinase C / metabolism*
  • Protein Kinases / chemistry
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Rats
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / immunology
  • Recombinant Fusion Proteins / metabolism
  • tau Proteins / chemistry
  • tau Proteins / immunology
  • tau Proteins / metabolism*


  • Antibodies, Monoclonal
  • Bacterial Proteins
  • Epitopes
  • Phosphoproteins
  • Recombinant Fusion Proteins
  • tau Proteins
  • Phosphoserine
  • Phosphotyrosine
  • Protein Kinases
  • PknA protein, Nostoc sp. PCC 7120
  • Glycogen Synthase Kinases
  • Protein Kinase C
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Glycogen Synthase Kinase 3