title: Pax5 promotes B lymphopoiesis and blocks T cell development by repressing Notch1.
abstract: The B lineage commitment factor Pax5 (BSAP) is exclusively expressed in B lymphocytes of the blood system. To study the effect of Pax5 on the development of other hematopoietic lineages, we generated a heterozygous knockin mouse carrying a Pax5 minigene under the control of the Ikaros locus. Conditional and constitutive activation of the Ik(Pax5) allele demonstrated that precocious Pax5 expression in hematopoietic stem cells and progenitors failed to interfere with myeloid development and only weakly affected erythroblast formation. Instead, pan-hematopoietic Pax5 expression strongly promoted B cell development at the expense of T lymphopoiesis. Pax5 thereby interfered with T lineage commitment and early thymocyte development by repressing the transcription of the T cell specification gene Notch1.
authors.affiliation: Research Institute of Molecular Pathology, Vienna Biocenter, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.
authors.forename: Abdallah
authors.initials: A
authors.lastname: Souabni
authors.forename: Cesar
authors.initials: C
authors.lastname: Cobaleda
authors.forename: Michael
authors.initials: M
authors.lastname: Schebesta
authors.forename: Meinrad
authors.initials: M
authors.lastname: Busslinger
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D019070:Cell Lineage / Q000235:genetics / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology*; D018507:Gene Expression Regulation, Developmental / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D051757:PAX5 Transcription Factor; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology*
chemical_list: D004268:DNA-Binding Proteins; D008565:Membrane Proteins; C497762:Notch1 protein, mouse; D051757:PAX5 Transcription Factor; C497282:Pax5 protein, mouse; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D014157:Transcription Factors