Constitutive Notch signalling promotes CD4 CD8 thymocyte differentiation in the absence of the pre-TCR complex, by mimicking pre-TCR signals.
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.
Michie
Alison M
AM
Division of Cancer Sciences and Molecular Pathology, Section of Experimental Haematology, Royal Infirmary, University of Glasgow, Glasgow, UK.
Chan
Angela C
AC
Ciofani
Maria
M
Carleton
Michael
M
Lefebvre
Juliette M
JM
He
Yiping
Y
Allman
David M
DM
Wiest
David L
DL
Zúñiga-Pflücker
Juan Carlos
JC
Izon
David J
DJ
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D008213:Lymphocyte Activation; D054503:Lymphoid Progenitor Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains; D051881:Receptor, Notch1 / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
C497762:Notch1 protein, mouse; D051881:Receptor, Notch1; D011948:Receptors, Antigen, T-Cell