title: HOXA9 promotes hematopoietic commitment of human embryonic stem cells.
abstract: The molecular determinants regulating the specification of human embryonic stem cells (hESCs) into hematopoietic cells remain elusive. HOXA9 plays a relevant role in leukemogenesis and hematopoiesis. It is highly expressed in hematopoietic stem and progenitor cells (HSPCs) and is downregulated upon differentiation. Hoxa9-deficient mice display impaired hematopoietic development, and deregulation of HOXA9 expression is frequently associated with acute leukemia. Analysis of the genes differentially expressed in cord blood HSPCs vs hESC-derived HSPCs identified HOXA9 as the most downregulated gene in hESC-derived HSPCs, suggesting that expression levels of HOXA9 may be crucial for hematopoietic differentiation of hESC. Here we show that during hematopoietic differentiation of hESCs, HOXA9 expression parallels hematopoietic development, but is restricted to the hemogenic precursors (HEP) (CD31(+)CD34(+)CD45(-)), and diminishes as HEPs differentiate into blood cells (CD45(+)). Different gain-of-function and loss-of-function studies reveal that HOXA9 enhances hematopoietic differentiation of hESCs by specifically promoting the commitment of HEPs into primitive and total CD45(+) blood cells. Gene expression analysis suggests that nuclear factor-κB signaling could be collaborating with HOXA9 to increase hematopoietic commitment. However, HOXA9 on its own is not sufficient to confer in vivo long-term engraftment potential to hESC-hematopoietic derivatives, reinforcing the idea that additional molecular regulators are needed for the generation of definitive in vivo functional HSPCs from hESC.
authors.affiliation: Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, Granada, Spain;
authors.forename: Veronica
authors.initials: V
authors.lastname: Ramos-Mejía
authors.affiliation: Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, Granada, Spain;
authors.forename: Oscar
authors.initials: O
authors.lastname: Navarro-Montero
authors.affiliation: Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, Granada, Spain;
authors.forename: Verónica
authors.initials: V
authors.lastname: Ayllón
authors.affiliation: Josep Carreras Leukemia Research Institute, Cell Therapy Program, School of Medicine, University of Barcelona, Barcelona, Spain; and.
authors.forename: Clara
authors.initials: C
authors.lastname: Bueno
authors.affiliation: Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, Granada, Spain;
authors.forename: Tamara
authors.initials: T
authors.lastname: Romero
authors.affiliation: Centre for Genomics and Oncological Research, Pfizer/University of Granada/Andalusian Regional Government, Granada, Spain;
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Real
authors.affiliation: Josep Carreras Leukemia Research Institute, Cell Therapy Program, School of Medicine, University of Barcelona, Barcelona, Spain; and Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Menendez
mesh_terms: D000818:Animals; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D020868:Gene Silencing; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017493:Leukocyte Common Antigens / Q000378:metabolism; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID
chemical_list: D018398:Homeodomain Proteins; C097899:homeobox protein HOXA9; D017493:Leukocyte Common Antigens