Protein kinase Czeta phosphorylates nuclear factor of activated T cells and regulates its transactivating activity.
Although several isoforms of protein kinase C (PKC) have been implicated in T lymphocyte activation events, little is known about their mode of action. To address the role of PKCzeta in T cell activation, we have generated Jurkat T cell transfectants expressing either the wild type (J-PKCzeta) or "kinase-dead" mutant (J-PKCzeta(mut)) versions of this protein. Expression of PKCzeta but not PKCzeta(mut) increased transcriptional activation mediated by the NF-kappaB or nuclear factor of activated T cells (NFAT). PKCzeta cooperates with calcium ionophore and with NFAT1 or NFAT2 proteins to enhance transcriptional activation of a NFAT reporter construct. However, neither NFAT nuclear translocation nor DNA binding were in J-PKCzeta cells. Our results show that PKCzeta enhanced transcriptional activity mediated by Gal4-NFAT1 fusion proteins containing the N-terminal transactivation domain of human NFAT1. Interestingly, PKCzeta synergizes with calcineurin to induce transcriptional activation driven by the NFAT1 transactivation domain. Co-precipitation experiments showed physical interaction between PKCzeta and NFAT1 or NFAT2 isoforms. Even more, PKCzeta was able to phosphorylate recombinant glutathione S-transferase-NFAT1 (1-385) protein. These data reveal a new role of PKCzeta in T cells through the control of NFAT function by modulating the activity of its transactivation domain.
San-Antonio
Belén
B
Centro de Biologia Molecular, Consejo Superior de Investigaciones Cientificas, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain.
Iñiguez
Miguel A
MA
Fresno
Manuel
M
D015153:Blotting, Western; D019703:Calcineurin / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D008156:Luciferases / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D000099221:Protein Kinase C zeta
D019703:Calcineurin; D004268:DNA-Binding Proteins; D005982:Glutathione Transferase; D008156:Luciferases; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D020033:Protein Isoforms; D011493:Protein Kinase C; D014157:Transcription Factors; D000099221:Protein Kinase C zeta; C494003:NFATC1 protein, human; C494006:NFATC2 protein, human