Notch3 activation is sufficient but not required for inducing human T-lineage specification.
Although the role for the individual Notch receptors in early hematopoiesis have been thoroughly investigated in mouse, studies in human have been mostly limited to the use of pan-Notch inhibitors. However, such studies in human are important to predict potential side effects of specific Notch receptor blocking reagents because these are currently being considered as therapeutic tools to treat various Notch-dependent diseases. In this study, we studied the individual roles of Notch1 and Notch3 in early human hematopoietic lineage decisions, particularly during T-lineage specification. Although this process in mice is solely dependent on Notch1 activation, we recently reported Notch3 expression in human uncommitted thymocytes, raising the possibility that Notch3 mediates human T-lineage specification. Although expression of a constitutive activated form of Notch3 (ICN3) results in the induction of T-lineage specification in human CD34(+) hematopoietic progenitor cells, similar to ICN1 overexpression, loss-of-function studies using blocking Abs reveal that only Notch1, but not Notch3, is critical in this process. Blocking of Notch1 activation in OP9-DLL4 cocultures resulted in a complete block in T-lineage specification and induced monocytic and plasmacytoid dendritic cell differentiation instead. In fetal thymus organ cultures, impeded Notch1 activation resulted in B and dendritic cell development. In contrast, Notch3 blocking Abs only marginally affected T-lineage specification and hematopoietic differentiation with a slight increase in monocyte development. No induction of B or dendritic cell development was observed. Thus, our results unambiguously reveal a nonredundant role for Notch1 in human T-lineage specification, despite the expression of other Notch receptors.
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and.
Els
E
Waegemans
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and.
Inge
I
Van de Walle
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and.
Jelle
J
De Medts
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and.
Magda
M
De Smedt
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and.
Tessa
T
Kerre
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and.
Bart
B
Vandekerckhove
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and.
Georges
G
Leclercq
Medical Genetics Research Group and Centre for Molecular Medicine, School of Clinical and Laboratory Sciences, Faculty of Medicine and Human Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
Tao
T
Wang
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and.
Jean
J
Plum
Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, B-9000 Ghent, Belgium; and Tom.Taghon@ugent.be.
Tom
T
Taghon
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D019070:Cell Lineage / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D016130:Immunophenotyping; D054503:Lymphoid Progenitor Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D010641:Phenotype; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism; D000071656:Receptor, Notch3; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000378:metabolism*; D060168:Thymocytes / Q000166:cytology / Q000378:metabolism
C499374:NOTCH3 protein, human; D051881:Receptor, Notch1; D000071656:Receptor, Notch3; D051880:Receptors, Notch