title: Geminin deletion increases the number of fetal hematopoietic stem cells by affecting the expression of key transcription factors.
abstract: Balancing stem cell self-renewal and initiation of lineage specification programs is essential for the development and homeostasis of the hematopoietic system. We have specifically ablated geminin in the developing murine hematopoietic system and observed profound defects in the generation of mature blood cells, leading to embryonic lethality. Hematopoietic stem cells (HSCs) accumulated in the fetal liver following geminin ablation, while committed progenitors were reduced. Genome-wide transcriptome analysis identified key HSC transcription factors as being upregulated upon geminin deletion, revealing a gene network linked with geminin that controls fetal hematopoiesis. In order to obtain mechanistic insight into the ability of geminin to regulate transcription, we examined Hoxa9 as an example of a key gene in definitive hematopoiesis. We demonstrate that in human K562 cells geminin is associated with HOXA9 regulatory elements and its absence increases HOXA9 transcription similarly to that observed in vivo. Moreover, silencing geminin reduced recruitment of the PRC2 component SUZ12 to the HOXA9 locus and resulted in an increase in RNA polymerase II recruitment and H3K4 trimethylation (H3K4me3), whereas the repressive marks H3K9me3 and H3K27me3 were reduced. The chromatin landscape was also modified at the regulatory regions of HOXA10 and GATA1. K562 cells showed a reduced ability to differentiate to erythrocytes and megakaryocytes upon geminin silencing. Our data suggest that geminin is indispensable for fetal hematopoiesis and regulates the generation of a physiological pool of stem and progenitor cells in the fetal hematopoietic system.
authors.affiliation: Department of Physiology, Medical School, University of Patras, Rio, Patras 26504, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Karamitros
authors.affiliation: Department of Physiology, Medical School, University of Patras, Rio, Patras 26504, Greece.
authors.forename: Alexandra L
authors.initials: AL
authors.lastname: Patmanidi
authors.affiliation: Department of Physiology, Medical School, University of Patras, Rio, Patras 26504, Greece.
authors.forename: Panoraia
authors.initials: P
authors.lastname: Kotantaki
authors.affiliation: Division of Molecular Immunology, MRC/National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK.
authors.forename: Alexandre J
authors.initials: AJ
authors.lastname: Potocnik
authors.affiliation: European Molecular Biology Laboratory (EMBL), Core Facilities and Services, Meyerhofstraße 1, Heidelberg 69117, Germany.
authors.forename: Tomi
authors.initials: T
authors.lastname: Bähr-Ivacevic
authors.affiliation: European Molecular Biology Laboratory (EMBL), Core Facilities and Services, Meyerhofstraße 1, Heidelberg 69117, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Benes
authors.affiliation: Department of Biology, Medical School, University of Patras, Rio, Patras 26504, Greece.
authors.forename: Zoi
authors.initials: Z
authors.lastname: Lygerou
authors.affiliation: Division of Molecular Immunology, MRC/National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK dkiouss@nimr.mrc.ac.uk taraviras@med.upatras.gr.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Kioussis
authors.affiliation: Department of Physiology, Medical School, University of Patras, Rio, Patras 26504, Greece dkiouss@nimr.mrc.ac.uk taraviras@med.upatras.gr.
authors.forename: Stavros
authors.initials: S
authors.lastname: Taraviras
mesh_terms: D000818:Animals; D002452:Cell Count; D002454:Cell Differentiation; D019070:Cell Lineage; D049109:Cell Proliferation; D020964:Embryo Loss / Q000378:metabolism / Q000473:pathology; D044127:Epigenesis, Genetic; D005333:Fetus / Q000166:cytology*; D064248:Geminin / Q000172:deficiency* / Q000378:metabolism; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental; D063990:Gene Ontology; D056426:Genetic Loci; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D008099:Liver / Q000166:cytology / Q000196:embryology; D051379:Mice; D009363:Neoplasm Proteins; D063151:Polycomb Repressive Complex 2 / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics
chemical_list: D064248:Geminin; D006657:Histones; D018398:Homeodomain Proteins; D009363:Neoplasm Proteins; C430461:SUZ12 protein, human; D014157:Transcription Factors; C097899:homeobox protein HOXA9; D063151:Polycomb Repressive Complex 2
keywords: Cell cycle; Epigenetic regulation; Fetal hematopoiesis; Geminin; HoxA9; Mouse; Transcriptional regulation