Dysmegakaryopoiesis of FPD/AML pedigrees with constitutional RUNX1 mutations is linked to myosin II deregulated expression.
FPD/AML is a familial platelet disorder characterized by platelet defects, predisposition to acute myelogenous leukemia (AML) and germ-line heterozygous RUNX1 alterations. Here we studied the in vitro megakaryopoiesis of 3 FPD/AML pedigrees. A 60% to 80% decrease in the output of megakaryocytes (MKs) from CD34(+) was observed. MK ploidy level was low and mature MKs displayed a major defect in proplatelet formation. To explain these defects, we focused on myosin II expression as RUNX1 has been shown to regulate MYL9 and MYH10 in an inverse way. In FPD/AML MKs, expression of MYL9 and MYH9 was decreased, whereas MYH10 expression was increased and the MYH10 protein was still present in the cytoplasm of mature MKs. Myosin II activity inhibition by blebbistatin rescued the ploidy defect of FPD/AML MKs. Finally, we demonstrate that MYH9 is a direct target of RUNX1 by chromatin immunoprecipitation and luciferase assays and we identified new RUNX1 binding sites in the MYL9 promoter region. Together, these results demonstrate that the defects in megakaryopoiesis observed in FPD/AML are, in part, related to a deregulation of myosin IIA and IIB expression leading to both a defect in ploidization and proplatelet formation.
Institut National de la Santé et de la Recherche Médicale, Villejuif, France.
Dominique
D
Bluteau
Ana C
AC
Glembotsky
Anna
A
Raimbault
Nathalie
N
Balayn
Laure
L
Gilles
Philippe
P
Rameau
Paquita
P
Nurden
Marie Christine
MC
Alessi
Najet
N
Debili
William
W
Vainchenker
Paula G
PG
Heller
Remi
R
Favier
Hana
H
Raslova
D001791:Blood Platelet Disorders / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008156:Luciferases / Q000378:metabolism; D008297:Male; D008533:Megakaryocytes / Q000473:pathology*; D009154:Mutation / Q000235:genetics*; D024507:Nonmuscle Myosin Type IIA / Q000235:genetics / Q000378:metabolism*; D024501:Nonmuscle Myosin Type IIB / Q000235:genetics / Q000378:metabolism*; D010375:Pedigree; D011003:Ploidies; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D050676:Core Binding Factor Alpha 2 Subunit; D006576:Heterocyclic Compounds, 4 or More Rings; D012333:RNA, Messenger; C493728:RUNX1 protein, human; C472645:blebbistatin; D008156:Luciferases; D024507:Nonmuscle Myosin Type IIA; D024501:Nonmuscle Myosin Type IIB