title: Mechanisms underlying platelet function defect in a pedigree with familial platelet disorder with a predisposition to acute myelogenous leukemia: potential role for candidate RUNX1 targets.
abstract: BACKGROUND
  Familial platelet disorder with a predisposition to acute myelogenous leukemia (FPD/AML) is an inherited platelet disorder caused by a germline RUNX1 mutation and characterized by thrombocytopenia, a platelet function defect, and leukemia predisposition. The mechanisms underlying FPD/AML platelet dysfunction remain incompletely clarified. We aimed to determine the contribution of platelet structural abnormalities and defective activation pathways to the platelet phenotype. In addition, by using a candidate gene approach, we sought to identify potential RUNX1-regulated genes involved in these defects.
  
  
  METHODS
  Lumiaggregometry, α-granule and dense granule content and release, platelet ultrastructure, αIIb β3 integrin activation and outside-in signaling were assessed in members of one FPD/AML pedigree. Expression levels of candidate genes were measured and luciferase reporter assays and chromatin immunoprecipitation were performed to study NF-E2 regulation by RUNX1.
  
  
  RESULTS
  A severe decrease in platelet aggregation, defective αIIb β3 integrin activation and combined αδ storage pool deficiency were found. However, whereas the number of dense granules was markedly reduced, α-granule content was heterogeneous. A trend towards decreased platelet spreading was found, and β3 integrin phosphorylation was impaired, reflecting altered outside-in signaling. A decrease in the level of transcription factor p45 NF-E2 was shown in platelet RNA and lysates, and other deregulated genes included RAB27B and MYL9. RUNX1 was shown to bind to the NF-E2 promoter in primary megakaryocytes, and wild-type RUNX1, but not FPD/AML mutants, was able to activate NF-E2 expression.
  
  
  CONCLUSIONS
  The FPD/AML platelet function defect represents a complex trait, and RUNX1 orchestrates platelet function by regulating diverse aspects of this process. This study highlights the RUNX1 target NF-E2 as part of the molecular network by which RUNX1 regulates platelet biogenesis and function.
authors.affiliation: Departamento de Hematología Investigación, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
authors.forename: A C
authors.initials: AC
authors.lastname: Glembotsky
authors.forename: D
authors.initials: D
authors.lastname: Bluteau
authors.forename: Y R
authors.initials: YR
authors.lastname: Espasandin
authors.forename: N P
authors.initials: NP
authors.lastname: Goette
authors.forename: R F
authors.initials: RF
authors.lastname: Marta
authors.forename: C P
authors.initials: CP
authors.lastname: Marin Oyarzun
authors.forename: L
authors.initials: L
authors.lastname: Korin
authors.forename: P R
authors.initials: PR
authors.lastname: Lev
authors.forename: R P
authors.initials: RP
authors.lastname: Laguens
authors.forename: F C
authors.initials: FC
authors.lastname: Molinas
authors.forename: H
authors.initials: H
authors.lastname: Raslova
authors.forename: P G
authors.initials: PG
authors.lastname: Heller
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D001791:Blood Platelet Disorders / Q000097:blood* / Q000150:complications*; D001792:Blood Platelets / Q000166:cytology*; D050676:Core Binding Factor Alpha 2 Subunit / Q000378:metabolism*; D005192:Family Health; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D039661:Integrin beta3 / Q000378:metabolism; D015470:Leukemia, Myeloid, Acute / Q000097:blood* / Q000150:complications*; D008297:Male; D050984:NF-E2 Transcription Factor, p45 Subunit / Q000378:metabolism; D010375:Pedigree; D010641:Phenotype; D010766:Phosphorylation; D010974:Platelet Aggregation; D010979:Platelet Function Tests; D040201:Platelet Membrane Glycoprotein IIb / Q000378:metabolism; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism; D055815:Young Adult
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; D039661:Integrin beta3; D050984:NF-E2 Transcription Factor, p45 Subunit; C494692:NFE2 protein, human; D040201:Platelet Membrane Glycoprotein IIb; C493728:RUNX1 protein, human; D014443:Tyrosine; D000255:Adenosine Triphosphate
keywords: FPD/AML; NF-E2 transcription factor; RUNX1 protein; Rab27B protein, human; blood platelet disorder; platelet function tests