title: The EBF transcription factor Collier directly promotes Drosophila blood cell progenitor maintenance independently of the niche.
abstract: The maintenance of stem or progenitor cell fate relies on intrinsic factors as well as local cues from the cellular microenvironment and systemic signaling. In the lymph gland, an hematopoietic organ in Drosophila larva, a group of cells called the Posterior Signaling Centre (PSC), whose specification depends on the EBF transcription factor Collier (Col) and the HOX factor Antennapedia (Antp), has been proposed to form a niche required to maintain the pool of hematopoietic progenitors (prohemocytes). In contrast with this model, we show here that genetic ablation of the PSC does not cause an increase in blood cell differentiation or a loss of blood cell progenitors. Furthermore, although both col and Antp mutant larvae are devoid of PSC, the massive prohemocyte differentiation observed in col mutant is not phenocopied in Antp mutant. Interestingly, beside its expression in the PSC, Col is also expressed at low levels in prohemocytes and we show that this expression persists in PSC-ablated and Antp mutant larvae. Moreover, targeted knockdown and rescue experiments indicate that Col expression is required in the prohemocytes to prevent their differentiation. Together, our findings show that the PSC is dispensable for blood cell progenitor maintenance and reveal the key role of the conserved transcription factor Col as an intrinsic regulator of hematopoietic progenitor fate.
authors.affiliation: Université de Toulouse, Université Paul Sabatier (UPS), Centre de Biologie du Développement, Bâtiment 4R3, F-31062 Toulouse, France; CNRS, Centre de Biologie du Développement, UMR 5547, F-31062 Toulouse, France.
authors.forename: Billel
authors.initials: B
authors.lastname: Benmimoun
authors.affiliation: Université de Toulouse, Université Paul Sabatier (UPS), Centre de Biologie du Développement, Bâtiment 4R3, F-31062 Toulouse, France; CNRS, Centre de Biologie du Développement, UMR 5547, F-31062 Toulouse, France.
authors.forename: Cédric
authors.initials: C
authors.lastname: Polesello
authors.affiliation: Université de Toulouse, Université Paul Sabatier (UPS), Centre de Biologie du Développement, Bâtiment 4R3, F-31062 Toulouse, France; CNRS, Centre de Biologie du Développement, UMR 5547, F-31062 Toulouse, France lucas.waltzer@univ-tlse3.fr marc.haenlin@univ-tlse3.fr.
authors.forename: Marc
authors.initials: M
authors.lastname: Haenlin
authors.affiliation: Université de Toulouse, Université Paul Sabatier (UPS), Centre de Biologie du Développement, Bâtiment 4R3, F-31062 Toulouse, France; CNRS, Centre de Biologie du Développement, UMR 5547, F-31062 Toulouse, France lucas.waltzer@univ-tlse3.fr marc.haenlin@univ-tlse3.fr.
authors.forename: Lucas
authors.initials: L
authors.lastname: Waltzer
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D017353:Gene Deletion; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D006434:Hemocytes / Q000166:cytology / Q000378:metabolism; D007814:Larva / Q000166:cytology / Q000378:metabolism; D008198:Lymph Nodes / Q000166:cytology / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D034622:RNA Interference; D015398:Signal Transduction; D055153:Stem Cell Niche; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D029721:Drosophila Proteins; D014157:Transcription Factors; C104357:kn protein, Drosophila; D049452:Green Fluorescent Proteins
keywords: Drosophila; EBF; hematopoiesis; stem cell niche