Different thresholds of Notch signaling bias human precursor cells toward B-, NK-, monocytic/dendritic-, or T-cell lineage in thymus microenvironment

• Published in: Blood Vol. 106; no. 10; pp. 3498 - 3506
• Main Authors: De Smedt, Magda, Hoebeke, Inge, Reynvoet, Katia, Leclercq, Georges, Plum, Jean
• Format: Journal Article
• Language: English
• Published: Washington, DC Elsevier Inc 15.11.2005; The Americain Society of Hematology
• Subjects: Amyloid Precursor Protein Secretases; Animals; Antigens, CD - immunology; Aspartic Acid Endopeptidases; Biological and medical sciences; Dose-Response Relationship, Immunologic; Endopeptidases - immunology; Enzyme Inhibitors - pharmacology; Fetal Blood - cytology; Fetal Blood - immunology; Fundamental and applied biological sciences. Psychology; Fundamental immunology; gamma-Aminobutyric Acid - analogs & derivatives; gamma-Aminobutyric Acid - pharmacology; Gene Rearrangement, T-Lymphocyte - drug effects; Gene Rearrangement, T-Lymphocyte - immunology; Humans; Immunobiology; Leukocytes - immunology; Lymphoid cells: ontogeny, maturation, markers, receptors, circulation and recirculation; Mice; Organ Culture Techniques; Receptors, Antigen, T-Cell, alpha-beta - immunology; Receptors, Notch - immunology; Signal Transduction - drug effects; Signal Transduction - immunology; Stem Cells - cytology; Stem Cells - immunology; Thymus Gland - cytology; Thymus Gland - immunology; Triglycerides - pharmacology; Human; Dendritic cell; Lymphopoiesis; Notch receptor; Thymus gland; Natural killer T cell; Monocyte; Stem cell; Precursor cell; Cell microenvironment; Hematopoietic cell; B-Lymphocyte; Cell differentiation; Natural killer cell; Signaling pathway; Antigen presenting cell; Hematopoiesis; T-Lymphocyte
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2005-02-0496

Notch receptors are involved in lineage decisions in multiple developmental scenarios, including hematopoiesis. Here, we treated hybrid human-mouse fetal thymus organ culture with the γ-secretase inhibitor 7 (N-[N-(3,5-difluorophenyl)-l-alanyl]-S-phenyl-glycine t-butyl ester) (DAPT) to establish the role of Notch signaling in human hematopoietic lineage decisions. The effect of inhibition of Notch signaling was studied starting from cord blood CD34+ or thymic CD34+CD1-, CD34+CD1+, or CD4ISP progenitors. Treatment of cord blood CD34+ cells with low DAPT concentrations results in aberrant CD4ISP and CD4/CD8 double-positive (DP) thymocytes, which are negative for intracellular T-cell receptor β (TCRβ). On culture with intermediate and high DAPT concentrations, thymic CD34+CD1- cells still generate aberrant intracellular TCRβ- DP cells that have undergone DJ but not VDJ recombination. Inhibition of Notch signaling shifts differentiation into non-T cells in a thymic microenvironment, depending on the starting progenitor cells: thymic CD34+CD1+ cells do not generate non-T cells, thymic CD34+CD1- cells generate NK cells and monocytic/dendritic cells, and cord blood CD34+Lin- cells generate B, NK, and monocytic/dendritic cells in the presence of DAPT. Our data indicate that Notch signaling is crucial to direct human progenitor cells into the T-cell lineage, whereas it has a negative impact on B, NK, and monocytic/dendritic cell generation in a dose-dependent fashion.