Characterization of a novel interaction between transcription factor TFII-I and the inducible tyrosine kinase in T cells

Eur J Immunol. 2009 Sep;39(9):2584-95. doi: 10.1002/eji.200839031.

Abstract

TCR signaling leads to the activation of kinases such as inducible tyrosine kinase (Itk), a key regulatory protein in T-lymphocyte activation and function. The homolog of Itk in B cells is Bruton's tyrosine kinase, previously shown to bind and phosphorylate the transcription factor TFII-I. TFII-I plays major roles in transcription and signaling. Our purpose herein was twofold: first, to identify some of the molecular determinants involved in TFII-I activation downstream of receptor crosslinking in T cells and second, to uncover the existence of Itk-TFII-I signaling in T lymphocytes. We report for the first time that TFII-I is tyrosine phosphorylated upon TCR, TCR/CD43, and TCR/CD28 co-receptor engagement in human and/or murine T cells. We show that Itk physically interacts with TFII-I and potentiates TFII-I-driven c-fos transcription. We demonstrate that TFII-I is phosphorylated upon co-expression of WT, but not kinase-dead, or kinase-dead/R29C mutant Itk, suggesting these residues are important for TFII-I phosphorylation, presumably via an Itk-dependent mechanism. Structural analysis of TFII-I-Itk interactions revealed that the first 90 residues of TFII-I are dispensable for Itk binding. Mutations within Itk's kinase, pleckstrin-homology, and proline-rich regions did not abolish TFII-I-Itk binding. Our results provide an initial step in understanding the biological role of Itk-TFII-I signaling in T-cell function.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • B-Lymphocytes / immunology*
  • B-Lymphocytes / metabolism
  • CD28 Antigens / immunology
  • CD28 Antigens / metabolism
  • CD3 Complex / immunology
  • CD3 Complex / metabolism
  • Genes, fos / genetics
  • Genes, fos / immunology
  • Humans
  • Jurkat Cells
  • Leukosialin / immunology
  • Leukosialin / metabolism
  • Mice
  • Phosphorylation / immunology
  • Promoter Regions, Genetic / genetics
  • Promoter Regions, Genetic / immunology
  • Protein-Tyrosine Kinases / metabolism*
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism
  • Transcription Factors, TFII / metabolism*

Substances

  • CD28 Antigens
  • CD3 Complex
  • GTF2I protein, human
  • Leukosialin
  • SPN protein, human
  • Transcription Factors, TFII
  • Protein-Tyrosine Kinases
  • emt protein-tyrosine kinase