title: Dyserythropoiesis of myelodysplastic syndromes.
abstract: OBJECTIVE
  Myelodysplastic syndromes (MDS) are heterogeneous diseases of the hematopoietic stem cell in the elderly. Anemia is the main symptom that mostly correlates with dysplastic erythropoiesis in the bone marrow. We will review the recent advances in understanding the diverse mechanisms of dyserythropoiesis.
  
  
  RESULTS
  Dyserythropoiesis defined as 10% dysplastic erythroid cells in the bone marrow is found in more than 80% of early MDS. Immature erythroblasts accumulate at the expense of mature erythroblasts due to differentiation arrest and apoptosis. In early MDS with dyserythropoiesis, caspase-dependent cleavage of the erythroid transcription factor GATA-1 occurring in basophilic erythroblasts accounts for impairment of final maturation. Depending on initiating genetic alteration, specific mechanisms contribute to erythroid defect. In MDS with 5q deletion, the haploinsufficiency of ribosomal protein gene, RPS14, opposes the transition of immature to mature erythroblasts by inducing a p53-dependent ribosome stress, cell cycle arrest and apoptosis. Recent work identifies the activation of a p53-S100A8/9 innate immune pathway that both intrinsically and extrinsically contributes to defective erythropoiesis. In MDS with ring sideroblasts, a paradigm of dyserythropoiesis, a unique mutation in SF3B1 splicing factor gene induces a multiplicity of alterations at RNA level that deeply modifies the patterns of gene expression.
  
  
  CONCLUSIONS
  Insights in the pathophysiology of MDS with dyserythropoiesis may guide the choice of the appropriate therapy, for instance lenalidomide in MDS with del(5q). A better understanding of the mechanisms of dyserthropoiesis is required to treat anemia in non-del(5q) MDS, especially in case of resistance to first-line therapy by erythropoiesis-stimulating agents.
authors.affiliation: aInstitut Cochin, Inserm U1016, CNRS UMR8104, Université Paris Descartes bLaboratory of Excellence LabEx GR-Ex cAssistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris Centre, Hôpital Cochin, Service d'hématologie biologique, Paris, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Lefèvre
authors.forename: Sabrina
authors.initials: S
authors.lastname: Bondu
authors.forename: Salomé
authors.initials: S
authors.lastname: Le Goff
authors.forename: Olivier
authors.initials: O
authors.lastname: Kosmider
authors.forename: Michaela
authors.initials: M
authors.lastname: Fontenay
mesh_terms: D000748:Anemia, Macrocytic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000756:Anemia, Sideroblastic / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001853:Bone Marrow / Q000378:metabolism* / Q000473:pathology; D001854:Bone Marrow Cells / Q000378:metabolism* / Q000473:pathology; D002872:Chromosome Deletion; D002895:Chromosomes, Human, Pair 5 / Q000235:genetics / Q000378:metabolism; D041905:Erythroid Cells / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D004920:Erythropoiesis / Q000235:genetics; D050982:GATA1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007113:Immunity, Innate; D008928:Mitochondria / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D009190:Myelodysplastic Syndromes / Q000175:diagnosis / Q000209:etiology* / Q000378:metabolism*; D012326:RNA Splicing; D015398:Signal Transduction
chemical_list: D050982:GATA1 Transcription Factor