title: Eukaryotic translation initiation factor 6 is a novel regulator of reactive oxygen species-dependent megakaryocyte maturation.
abstract: BACKGROUND
  Ribosomopathies constitute a class of inherited disorders characterized by defects in ribosome biogenesis and function. Classically, bone marrow (BM) failure is a clinical symptom shared between these syndromes, including Shwachman-Bodian-Diamond syndrome (SBDS). Eukaryotic translation initiation factor 6 (eIF6) is a critical translation factor that rescues the quasilethal effect of the loss of the SBDS protein.
  
  
  OBJECTIVE
  To determine whether eIF6 activity is necessary for BM development.
  
  
  METHODS
  We used eIF6(+/-) mice and primary BM megakaryocytes to investigate the involvement of eIF6 in the regulation of hematopoiesis.
  
  
  RESULTS
  We provide evidence that reduced eIF6 expression negatively impacts on megakaryopoiesis. We show that inhibition of eIF6 leads to a reduction in cell size and mean ploidy level of megakaryocytes and a delay in megakaryocyte maturation by blocking the G1 /S transition. Consistent with this phenotype, only few megakaryocyte-forming proplatelets were found in eIF6(+/-) cells. We also discovered that, in eIF6(+/-) cells, the steady-state abundance of mitochondrial respiratory chain complex I-encoding mRNAs is decreased, resulting in decreased reactive oxygen species (ROS) production. Intriguingly, connectivity map analysis showed that eIF6-mediated changes overlap with specific translational inhibitors. eIF6 is a translation factor acting downstream of insulin/phorbol 12-myristate 13-acetate (PMA) stimulation. PMA treatment significantly restored eIF6(+/-) megakaryocyte maturation, indicating that activation of eIF6 is essential for the rescue of the phenotype.
  
  
  CONCLUSIONS
  Taken together, our results show a role for eIF6-driven translation in megakaryocyte development, and unveil the novel connection between translational control and ROS production in this cell subset.
authors.affiliation: Molecular Histology and Cell Growth Unit, National Institute of Molecular Genetics - INGM, 'Romeo ed Enrica Invernizzi', Milan, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Ricciardi
authors.affiliation: Molecular Histology and Cell Growth Unit, National Institute of Molecular Genetics - INGM, 'Romeo ed Enrica Invernizzi', Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Miluzio
authors.affiliation: Molecular Histology and Cell Growth Unit, National Institute of Molecular Genetics - INGM, 'Romeo ed Enrica Invernizzi', Milan, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Brina
authors.affiliation: Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
authors.forename: K
authors.initials: K
authors.lastname: Clarke
authors.affiliation: Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
authors.forename: M
authors.initials: M
authors.lastname: Bonomo
authors.affiliation: Immunopathology Unit, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Aiolfi
authors.affiliation: Immunopathology Unit, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: L G
authors.initials: LG
authors.lastname: Guidotti
authors.affiliation: Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
authors.forename: F
authors.initials: F
authors.lastname: Falciani
authors.affiliation: Molecular Histology and Cell Growth Unit, National Institute of Molecular Genetics - INGM, 'Romeo ed Enrica Invernizzi', Milan, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Biffo
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism; D001855:Bone Marrow Diseases / Q000378:metabolism; D048429:Cell Size; D002478:Cells, Cultured; D042002:Chromatin Assembly and Disassembly / Q000502:physiology; D015536:Down-Regulation; D042967:Electron Transport Complex I / Q000096:biosynthesis / Q000235:genetics; D010188:Exocrine Pancreatic Insufficiency / Q000378:metabolism; D016193:G1 Phase / Q000502:physiology; D008068:Lipomatosis / Q000378:metabolism; D008297:Male; D008533:Megakaryocytes / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D010448:Peptide Initiation Factors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D011003:Ploidies; D014176:Protein Biosynthesis / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism*; D054683:Ribosome Subunits, Large, Eukaryotic / Q000378:metabolism; D000081003:Shwachman-Diamond Syndrome; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D034061:Thrombopoiesis / Q000502:physiology*
chemical_list: C115811:Itgb4bp protein, mouse; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D042967:Electron Transport Complex I; D013755:Tetradecanoylphorbol Acetate
keywords: initiation factors; megakaryocytes; platelets; reactive oxygen species; thrombocytopenia