title: Rho kinase inhibition drives megakaryocyte polyploidization and proplatelet formation through MYC and NFE2 downregulation.
abstract: The processes of megakaryocyte polyploidization and demarcation membrane system (DMS) formation are crucial for platelet production, but the mechanisms controlling these processes are not fully determined. Inhibition of Rho kinase (ROCK) signalling leads to increased polyploidization in umbilical cord blood-derived megakaryocytes. To extend these findings we determined the effect of ROCK inhibition on development of the DMS and on proplatelet formation. The underlying mechanisms were explored by analysing the effect of ROCK inhibition on the expression of MYC and NFE2, which encode two transcription factors critical for megakaryocyte development. ROCK inhibition promoted DMS formation, and increased proplatelet formation and platelet release. Rho kinase inhibition also downregulated MYC and NFE2 expression in mature megakaryocytes, and this down-regulation correlated with increased proplatelet formation. Our findings suggest a model whereby ROCK inhibition drives polyploidization, DMS growth and proplatelet formation late in megakaryocyte maturation through downregulation of MYC and NFE2 expression.
authors.affiliation: Platelet Biology Laboratory, Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY, USA; Cellular Therapy Laboratory, Hematology Division, Santa Casa Medical School, São Paulo, Brazil.
authors.forename: Mauro P
authors.initials: MP
authors.lastname: Avanzi
authors.forename: Francine
authors.initials: F
authors.lastname: Goldberg
authors.forename: Jennifer
authors.initials: J
authors.lastname: Davila
authors.forename: Dante
authors.initials: D
authors.lastname: Langhi
authors.forename: Carlos
authors.initials: C
authors.lastname: Chiattone
authors.forename: William Beau
authors.initials: WB
authors.lastname: Mitchell
mesh_terms: D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D018929:Cell Culture Techniques; D002462:Cell Membrane / Q000502:physiology; D015536:Down-Regulation; D016259:Genes, myc; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods; D006801:Humans; D008533:Megakaryocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D050984:NF-E2 Transcription Factor, p45 Subunit / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D011123:Polyploidy; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000097:blood / Q000235:genetics
chemical_list: C489427:MYC protein, human; D050984:NF-E2 Transcription Factor, p45 Subunit; C494692:NFE2 protein, human; D016271:Proto-Oncogene Proteins c-myc; D054460:rho-Associated Kinases
keywords: MYC; NFE2; Rho kinase; megakaryocytopoiesis; polyploidization; proplatelet formation