Direct interaction between protein kinase C theta (PKC theta) and 14-3-3 tau in T cells: 14-3-3 overexpression results in inhibition of PKC theta translocation and function

Mol Cell Biol. 1996 Oct;16(10):5782-91. doi: 10.1128/mcb.16.10.5782.

Abstract

Recent studies have documented direct interactions between 14-3-3 proteins and several oncogene and proto-oncogene products involved in signal transduction pathways. Studies on the effects of 14-3-3 proteins on protein kinase C (PKC) activity in vitro have reported conflicting results, and previous attempts to demonstrate a direct association between PKC and 14-3-3 were unsuccessful. Here, we examined potential physical and functional interactions between PKC theta, a Ca(2+)-independent PKC enzyme which is expressed selectively in T lymphocytes, and the 14-3-3 tau isoform in vitro and in intact T cells. PKC theta and 14-3-3 tau coimmunoprecipitated from Jurkat T cells, and recombinant 14-3-3 tau interacted directly with purified PKC theta in vitro. Transient overexpression of 14-3-3 tau suppressed stimulation of the interleukin 2 (IL-2) promoter mediated by cotransfected wild-type or constitutively active PKC theta, as well as by endogenous PKC in ionomycin- and/or phorbol ester-stimulated cells. This did not represent a general inhibition of activation events, since PKC-independent (but Ca(2+)-dependent) activation of an IL-4 promoter element was not inhibited by 14-3-3 tau under similar conditions. Overexpression of wild-type 14-3-3 tau also inhibited phorbol ester-induced PKC theta translocation from the cytosol to the membrane in Jurkat cells, while a membrane-targeted form of 14-3-3 tau caused increased localization of PKC theta in the particulate fraction in unstimulated cells. Membrane-targeted 14-3-3 tau was more effective than wild-type 14-3-3 tau in suppressing PKC theta-dependent IL-2 promoter activity, suggesting that 14-3-3 tau inhibits the function of PKC theta not only by preventing its translocation to the membrane but also by associating with it. The interaction between 14-3-3 and PKC theta may represent an important general mechanism for regulating PKC-dependent signals and, more specifically, PKC theta-mediated functions during T-cell activation.

Publication types

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

MeSH terms

  • 14-3-3 Proteins
  • Blotting, Western
  • Chloramphenicol O-Acetyltransferase / biosynthesis
  • Gene Expression Regulation
  • Glutathione Transferase / biosynthesis
  • Humans
  • Interleukin-2 / biosynthesis
  • Interleukin-2 / genetics
  • Ionomycin / pharmacology
  • Isoenzymes / biosynthesis
  • Isoenzymes / isolation & purification
  • Isoenzymes / metabolism*
  • Jurkat Cells
  • Mutagenesis, Site-Directed
  • Point Mutation
  • Promoter Regions, Genetic
  • Protein Biosynthesis
  • Protein Kinase C / biosynthesis
  • Protein Kinase C / isolation & purification
  • Protein Kinase C / metabolism*
  • Protein Kinase C-theta
  • Proteins / isolation & purification
  • Proteins / metabolism*
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Sequence Tagged Sites
  • Signal Transduction
  • T-Lymphocytes / metabolism*
  • Tetradecanoylphorbol Acetate / pharmacology
  • Transfection
  • Tyrosine 3-Monooxygenase*

Substances

  • 14-3-3 Proteins
  • Interleukin-2
  • Isoenzymes
  • Proteins
  • Recombinant Proteins
  • Ionomycin
  • Tyrosine 3-Monooxygenase
  • Chloramphenicol O-Acetyltransferase
  • Glutathione Transferase
  • PRKCQ protein, human
  • Protein Kinase C
  • Protein Kinase C-theta
  • Tetradecanoylphorbol Acetate