Notch signaling is required for proliferation but not for differentiation at a well-defined β-selection checkpoint during human T-cell development

• Published in: Blood 2009-04, Vol.113 (14), p.3254-3263
• Main Authors: Taghon, Tom, Van de Walle, Inge, De Smet, Greet, De Smedt, Magda, Leclercq, Georges, Vandekerckhove, Bart, Plum, Jean
• Format: Article
• Language: English
• Subjects: Antigens, CD34 - metabolism; Biological and medical sciences; CD28 Antigens - metabolism; CD4 Antigens - metabolism; CD8 Antigens - metabolism; Cell Differentiation - genetics; Cell Differentiation - immunology; Cell Proliferation; Cells, Cultured; DNA-Binding Proteins - genetics; DNA-Binding Proteins - physiology; Gene Rearrangement, beta-Chain T-Cell Antigen Receptor - physiology; Genes, Dominant - physiology; Genes, T-Cell Receptor beta - physiology; Hematologic and hematopoietic diseases; Humans; Medical sciences; Models, Biological; Receptors, Notch - genetics; Receptors, Notch - physiology; Signal Transduction - genetics; Signal Transduction - physiology; T-Lymphocytes - metabolism; T-Lymphocytes - physiology; Thymus Gland - cytology; Thymus Gland - metabolism; Thymus Gland - physiology; Trans-Activators - genetics; Trans-Activators - physiology; Transcription Factors
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2008-07-168906

Notch signaling is absolutely required for β-selection during mouse T-cell development, both for differentiation and proliferation. In this report, we investigated whether Notch has an equally important role during human T-cell development. We show that human CD34+ thymocytes can differentiate into CD4+CD8β+ double positive (DP) thymocytes in the absence of Notch signaling. While these DP cells phenotypically resemble human β-selected cells, they lack a T-cell receptor (TCR)–β chain. Therefore, we characterized the β-selection checkpoint in human T-cell development, using CD28 as a differential marker at the immature single positive CD4+CD3−CD8α− stage. Through intracellular TCR-β staining and gene expression analysis, we show that CD4+CD3−CD8α−CD28+ thymocytes have passed the β-selection checkpoint, in contrast to CD4+CD3−CD8α−CD28− cells. These CD4+CD3−CD8α−CD28+ thymocytes can efficiently differentiate into CD3+TCRαβ+ human T cells in the absence of Notch signaling. Importantly, preselection CD4+CD3−CD8α−CD28− thymocytes can also differentiate into CD3+TCRαβ+ human T cells without Notch activation when provided with a rearranged TCR-β chain. Proliferation of human thymocytes, however, is clearly Notch-dependent. Thus, we have characterized the β-selection checkpoint during human T-cell development and show that human thymocytes require Notch signaling for proliferation but not for differentiation at this stage of development.