Protein kinase A negatively modulates the nuclear accumulation of NF-ATc1 by priming for subsequent phosphorylation by glycogen synthase kinase-3

J Biol Chem. 2002 Dec 13;277(50):48664-76. doi: 10.1074/jbc.M207029200. Epub 2002 Sep 25.

Abstract

The nuclear localization and transcriptional activity of the NF-ATc family of transcription factors, essential to many developmental, differentiation, and adaptation processes, are determined by the opposing activities of the phosphatase calcineurin, which promotes nuclear accumulation of NF-ATc, and several kinases, which promote cytoplasmic accumulation. Many reports suggest that protein kinase A (PKA) negatively modulates calcineurin-mediated NF-ATc activation. Here we show that overexpression of PKA causes phosphorylation and cytoplasmic accumulation of NF-ATc1 in direct opposition to calcineurin by phosphorylating Ser-245, Ser-269, and Ser-294 in the conserved serine-proline repeat domain, and that mutation of these serines blocks the effect of PKA. Activation of endogenous PKA is similarly able to promote phosphorylation of these sites on NF-ATc1 in two lymphoid cell lines. We further show that a complete block of NF-ATc1 nuclear localization by PKA requires a second kinase activity that can be supplied by glycogen synthase kinase-3 (GSK-3), and that mutation of either the PKA phosphorylation sites or the upstream GSK-3 sites prevents the effect of PKA. Thus, we propose that PKA functions cooperatively as a priming kinase for further phosphorylation by GSK-3 to oppose calcineurin-mediated nuclear accumulation and transcriptional activity of NF-ATc1 and that, through this mechanism, PKA may be an important modulator of many NF-ATc-dependent processes.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Calcium / metabolism
  • Cell Line
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism*
  • Cyclic AMP / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Glycogen Synthase Kinase 3 / metabolism*
  • Humans
  • Ionomycin / pharmacology
  • Molecular Sequence Data
  • NFATC Transcription Factors
  • Nuclear Proteins*
  • Phosphorylation
  • Serine / metabolism
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Transcription, Genetic
  • Transfection

Substances

  • DNA-Binding Proteins
  • NFATC Transcription Factors
  • NFATC1 protein, human
  • Nuclear Proteins
  • Transcription Factors
  • Serine
  • Ionomycin
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Glycogen Synthase Kinase 3
  • Calcium