Constitutive Notch signalling promotes CD4 CD8 thymocyte differentiation in the absence of the pre-TCR complex, by mimicking pre-TCR signals

Int Immunol. 2007 Dec;19(12):1421-30. doi: 10.1093/intimm/dxm113. Epub 2007 Nov 1.

Abstract

Notch1 signalling is essential for the commitment of multipotent lymphocyte precursors towards the alphabeta T-cell lineage and plays an important role in regulating beta-selection in CD4(-)CD8(-) double-negative (DN) thymocytes. However, the role played by Notch in promoting the development of CD4(+)CD8(+) double-positive (DP) thymocytes is poorly characterized. Here, we demonstrate that the introduction of a constitutively active Notch1 (ICN1) construct into RAG(-/-) lymphocyte precursors resulted in the generation of DP thymocytes in in vitro T-cell culture systems. Notably, developmental rescue was dependent not only on the presence of an intact Notch1 RAM domain but also on Delta-like signals, as ICN1-induced DP development in RAG(-/-) thymocytes occurred within an intact thymus or in OP9-DL1 co-cultures, but not in OP9-control co-cultures. Interestingly, ICN1 expression in SLP-76(-/-) precursors resulted in only a minimal developmental rescue to the immature CD8(+) single-positive stage, suggesting that Notch is utilizing the same signalling pathway as the pre-TCR complex. In support of this, ICN1 introduction resulted in the activation of the ERK-MAPK-signalling cascade in RAG(-/-) thymocytes. Taken together, these studies demonstrate that constitutive Notch signalling can bypass beta-selection during early T-cell development by inducing pre-TCR-like signals within a T-cell-promoting environment.

Publication types

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

MeSH terms

  • Animals
  • CD4-Positive T-Lymphocytes / cytology
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / cytology
  • CD8-Positive T-Lymphocytes / immunology
  • Cell Differentiation
  • Lymphocyte Activation
  • Lymphoid Progenitor Cells / cytology*
  • Lymphoid Progenitor Cells / immunology
  • Lymphoid Progenitor Cells / metabolism*
  • Mice
  • Mice, Mutant Strains
  • Receptor, Notch1 / metabolism*
  • Receptors, Antigen, T-Cell / immunology*
  • Signal Transduction
  • T-Lymphocytes / cytology
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism*
  • Thymus Gland / cytology
  • Thymus Gland / immunology*
  • Thymus Gland / metabolism

Substances

  • Notch1 protein, mouse
  • Receptor, Notch1
  • Receptors, Antigen, T-Cell