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.
Mesh Terms:
Blotting, Western, Calcineurin, Cell Nucleus, DNA-Binding Proteins, Gene Expression Regulation, Enzymologic, Genes, Reporter, Glutathione Transferase, Humans, Jurkat Cells, Luciferases, NFATC Transcription Factors, Nuclear Proteins, Phosphorylation, Plasmids, Precipitin Tests, Protein Binding, Protein Isoforms, Protein Kinase C, Protein Structure, Tertiary, Transcription Factors, Transcriptional Activation, Transfection
Blotting, Western, Calcineurin, Cell Nucleus, DNA-Binding Proteins, Gene Expression Regulation, Enzymologic, Genes, Reporter, Glutathione Transferase, Humans, Jurkat Cells, Luciferases, NFATC Transcription Factors, Nuclear Proteins, Phosphorylation, Plasmids, Precipitin Tests, Protein Binding, Protein Isoforms, Protein Kinase C, Protein Structure, Tertiary, Transcription Factors, Transcriptional Activation, Transfection
J. Biol. Chem.
Date: Jul. 26, 2002
PubMed ID: 12021260
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