title: Pbx1 restrains myeloid maturation while preserving lymphoid potential in hematopoietic progenitors.
abstract: The capacity of the hematopoietic system to promptly respond to peripheral demands relies on adequate pools of progenitors able to transiently proliferate and differentiate in a regulated manner. However, little is known about factors that may restrain progenitor maturation to maintain their reservoirs. Conditional knockout mice for the Pbx1 proto-oncogene have a significant reduction in lineage-restricted progenitors in addition to a profound defect in hematopoietic stem cell (HSC) self-renewal. Through analysis of purified progenitor proliferation, differentiation capacity and transcriptional profiling, we demonstrate that Pbx1 regulates the lineage-specific output of multipotent and oligopotent progenitors. In the absence of Pbx1 multipotent progenitor (MPP) and common myeloid progenitor (CMP) pools are reduced due to aberrantly rapid myeloid maturation. This is associated with premature expression of myeloid differentiation genes and decreased maintenance of proto-oncogene transcriptional pathways, including reduced expression of Meis1, a Pbx1 dimerization partner, and its subordinate transcriptional program. Conversely, Pbx1 maintains the lymphoid differentiation potential of lymphoid-primed MPPs (LMPPs) and common lymphoid progenitors (CLPs), whose reduction in the absence of Pbx1 is associated with a defect in lymphoid priming that is also present in CMPs, which persistently express lymphoid and HSC genes underlying a previously unappreciated lineage promiscuity that is maintained by Pbx1. These results demonstrate a role for Pbx1 in restraining myeloid maturation while maintaining lymphoid potential to appropriately regulate progenitor reservoirs.
authors: Milan Unit, Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Milan, Italy.
authors: Francesca
authors: F
authors: Ficara
authors: Laura
authors: L
authors: Crisafulli
authors: Chenwei
authors: C
authors: Lin
authors: Masayuki
authors: M
authors: Iwasaki
authors: Kevin S
authors: KS
authors: Smith
authors: Luca
authors: L
authors: Zammataro
authors: Michael L
authors: ML
authors: Cleary
mesh_terms: D000818:Animals; D019070:Cell Lineage / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006410:Hematopoiesis; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000235:genetics; D054503:Lymphoid Progenitor Cells / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D000075064:Myeloid Ecotropic Viral Integration Site 1 Protein; D023461:Myeloid Progenitor Cells / Q000502:physiology*; D009363:Neoplasm Proteins / Q000378:metabolism*; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D055503:Protein Multimerization; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D018398:Homeodomain Proteins; C000616392:Meis1 protein, mouse; D000075064:Myeloid Ecotropic Viral Integration Site 1 Protein; D009363:Neoplasm Proteins; C481797:Pbx1 protein, mouse; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D014157:Transcription Factors
keywords: CLPs; CMPs; MPPs; Myeloid differentiation; Pbx1
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