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J Biol Chem. 2002 Jul 26;277(30):27073-80. Epub 2002 May 20.

Protein kinase Czeta phosphorylates nuclear factor of activated T cells and regulates its transactivating activity.

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  • 1Centro de Biologia Molecular, Consejo Superior de Investigaciones Cientificas, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain.

Abstract

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.

PMID:
12021260
[PubMed - indexed for MEDLINE]
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