title: Conversion of mature B cells into T cells by dedifferentiation to uncommitted progenitors.
abstract: Lineage commitment and differentiation to a mature cell type are considered to be unidirectional and irreversible processes under physiological conditions. The commitment of haematopoietic progenitors to the B-cell lineage and their development to mature B lymphocytes critically depend on the transcription factor encoded by the paired box gene 5 (Pax5). Here we show that conditional Pax5 deletion in mice allowed mature B cells from peripheral lymphoid organs to dedifferentiate in vivo back to early uncommitted progenitors in the bone marrow, which rescued T lymphopoiesis in the thymus of T-cell-deficient mice. These B-cell-derived T lymphocytes carried not only immunoglobulin heavy- and light-chain gene rearrangements but also participated as functional T cells in immune reactions. Mice lacking Pax5 in mature B cells also developed aggressive lymphomas, which were identified by their gene expression profile as progenitor cell tumours. Hence, the complete loss of Pax5 in late B cells could initiate lymphoma development and uncovered an extraordinary plasticity of mature peripheral B cells despite their advanced differentiation stage.
authors.affiliation: Research Institute of Molecular Pathology, Vienna Biocenter, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.
authors.forename: César
authors.initials: C
authors.lastname: Cobaleda
authors.forename: Wolfram
authors.initials: W
authors.lastname: Jochum
authors.forename: Meinrad
authors.initials: M
authors.lastname: Busslinger
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology*; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D017353:Gene Deletion; D015322:Gene Rearrangement, B-Lymphocyte / Q000235:genetics; D007136:Immunoglobulins / Q000235:genetics / Q000276:immunology; D008223:Lymphoma / Q000235:genetics / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D051757:PAX5 Transcription Factor / Q000172:deficiency / Q000235:genetics; D013234:Stem Cells / Q000166:cytology*; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D007136:Immunoglobulins; D051757:PAX5 Transcription Factor; C497282:Pax5 protein, mouse; C499308:Rag2 protein, mouse