CD45 recruits adapter protein DOK-1 and negatively regulates JAK-STAT signaling in hematopoietic cells

Mol Immunol. 2009 Jul;46(11-12):2167-77. doi: 10.1016/j.molimm.2009.04.032. Epub 2009 May 28.


It has been extensively documented that CD45 positively regulates T cell receptor-mediated signaling through the activation of Src-family kinases. The mechanism whereby CD45 negatively regulates the JAK/STAT pathway, however, has not been fully elucidated. Here we describe the mechanism by which CD45 negatively regulates the JAK/STAT pathway through the recruitment of the inhibitory molecule Downstream of Kinase 1 (DOK-1) in hematopoietic cells. We present evidences that CD45 recruits DOK-1 to associate with tyrosine-phosphorylated DOK-1, and that the DOK-1-Y296F mutant completely abrogates its interaction with CD45. Moreover, CD45 expression is required for DOK-1 targeting to the plasma membrane in response to anti-CD3 stimulation. Functional studies further showed that stable expression of DOK-1 in K562 cells markedly decreased both JAK-2 and STAT-3/5 phosphorylation following IL-3 and IFN-alpha stimulation. Likewise, stable expression of DOK-1 in Jurkat cells significantly decreased JAK-2 phosphorylation. Similarly, both IL-3 and IFN-alpha-induced JAK-2 phosphorylations were significantly increased in CD45 deficient Jurkat cells. Consistently, silencing of the DOK-1 gene resulted in rescue of MAP kinases and JAKs activities in CD45 positive Jurkat cells. Accordingly, CD45 recruits adaptor DOK-1 to the proximal plasma membrane to serve as a downstream effector, resulting in negative regulation of the JAK/STAT signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Membrane / metabolism
  • DNA-Binding Proteins / metabolism*
  • Humans
  • Interferon-alpha / metabolism
  • Interferon-alpha / pharmacology
  • Interleukin-3 / metabolism
  • Interleukin-3 / pharmacology
  • Janus Kinase 2 / metabolism*
  • Jurkat Cells
  • K562 Cells
  • Leukocyte Common Antigens / genetics
  • Leukocyte Common Antigens / physiology*
  • MAP Kinase Signaling System / physiology
  • Mutation
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Protein Binding
  • RNA-Binding Proteins / metabolism*
  • STAT3 Transcription Factor / metabolism*
  • STAT5 Transcription Factor / metabolism*
  • Signal Transduction
  • T-Lymphocytes / metabolism


  • DNA-Binding Proteins
  • DOK1 protein, human
  • Interferon-alpha
  • Interleukin-3
  • Phosphoproteins
  • RNA-Binding Proteins
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • STAT5 Transcription Factor
  • Janus Kinase 2
  • Leukocyte Common Antigens