IL-7-induced phosphorylation of the adaptor Crk-like and other targets

Cell Signal. 2018 Jul:47:131-141. doi: 10.1016/j.cellsig.2018.03.008. Epub 2018 Mar 24.

Abstract

IL-7 is required for T cell differentiation and mature T cell homeostasis and promotes pro-B cell proliferation and survival. Tyrosine phosphorylation plays a central role in IL-7 signaling. We identified by two-dimensional electrophoresis followed by anti-phosphotyrosine immunoblotting and mass spectrometry sixteen tyrosine phosphorylated proteins from the IL-7-dependent cell line D1. IL-7 stimulation induced the phosphorylation of the proteins STI1, ATIC and hnRNPH, involved in pathways related to survival, proliferation and gene expression, respectively, and increased the phosphorylation of CrkL, a member of a family of adaptors including the highly homologous Crk isoforms CrkII and CrkI, important in multiple signaling pathways. We observed an increased phosphorylation of CrkL in murine pro-B cells and in murine and human T cells. In addition, IL-7 increased the association of CrkL with the transcription factor Stat5, essential for IL-7 pro-survival activity. The selective tyrosine kinase inhibitor Imatinib. counteracted the IL-7 pro-survival effect in D1 cells and decreased CrkL phosphorylation. These data suggested that CrkL could play a pro-survival role in IL-7-mediated signaling. We observed that pro-B cells also expressed, in addition to CrkL, the Crk isoforms CrkII and CrkI and therefore utilized pro-B cells conditionally deficient in all three to evaluate the role of these proteins. The observation that the IL-7 pro-survival effect was reduced in Crk/CrkL conditionally-deficient pro-B cells further pointed to a pro-survival role of these adaptors. To further evaluate the role of these proteins, gene expression studies were performed in Crk/CrkL conditionally-deficient pro-B cells. IL-7 decreased the transcription of the receptor LAIR1, which inhibits B cell proliferation, in a Crk/CrkL-dependent manner, suggesting that the Crk family of proteins may promote pro-B cell proliferation. Our data contribute to the understanding of IL-7 signaling and suggest the involvement of Crk family proteins in pathways promoting survival and proliferation.

Keywords: Apoptosis; Crk-like; Imatinib; Interleukin 7; LAIR1; Tyrosine phosphorylation.

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Apoptosis / drug effects
  • B-Lymphocytes / cytology
  • B-Lymphocytes / drug effects
  • B-Lymphocytes / metabolism
  • Gene Expression Regulation / drug effects
  • Humans
  • Imatinib Mesylate / pharmacology
  • Interleukin-7 / pharmacology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phosphorylation / drug effects
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • STAT5 Transcription Factor / metabolism
  • Signal Transduction / drug effects
  • T-Lymphocytes / cytology
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • CRKL protein
  • Interleukin-7
  • Nuclear Proteins
  • Protein Isoforms
  • STAT5 Transcription Factor
  • Imatinib Mesylate