title: Canonical Wnt signaling in megakaryocytes regulates proplatelet formation.
abstract: Wnt signaling is involved in numerous aspects of vertebrate development and homeostasis, including the formation and function of blood cells. Here, we show that canonical and noncanonical Wnt signaling pathways are present and functional in megakaryocytes (MKs), with several Wnt effectors displaying MK-restricted expression. Using the CHRF288-11 cell line as a model for human MKs, the canonical Wnt3a signal was found to induce a time and dose-dependent increase in β-catenin expression. β-catenin accumulation was inhibited by the canonical antagonist dickkopf-1 (DKK1) and by the noncanonical agonist Wnt5a. Whole genome expression analysis demonstrated that Wnt3a and Wnt5a regulated distinct patterns of gene expression in MKs, and revealed a further interplay between canonical and noncanonical Wnt pathways. Fetal liver cells derived from low-density-lipoprotein receptor-related protein 6-deficient mice (LRP6(-/-)), generated dramatically reduced numbers of MKs in culture of lower ploidy (2N and 4N) than wild-type controls, implicating LRP6-dependent Wnt signaling in MK proliferation and maturation. Finally, in wild-type mature murine fetal liver-derived MKs, Wnt3a potently induced proplatelet formation, an effect that could be completely abrogated by DKK1. These data identify novel extrinsic regulators of proplatelet formation, and reveal a profound role for Wnt signaling in platelet production.
authors.affiliation: UCD Conway Institute, School of Biomedical and Biomolecular Science, University College Dublin, Dublin, Ireland.
authors.forename: Iain C
authors.initials: IC
authors.lastname: Macaulay
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Thon
authors.forename: Marloes R
authors.initials: MR
authors.lastname: Tijssen
authors.forename: Brian M
authors.initials: BM
authors.lastname: Steele
authors.forename: Bryan T
authors.initials: BT
authors.lastname: MacDonald
authors.forename: Gerardene
authors.initials: G
authors.lastname: Meade
authors.forename: Philippa
authors.initials: P
authors.lastname: Burns
authors.forename: Augusto
authors.initials: A
authors.lastname: Rendon
authors.forename: Vishal
authors.initials: V
authors.lastname: Salunkhe
authors.forename: Ronan P
authors.initials: RP
authors.lastname: Murphy
authors.forename: Cavan
authors.initials: C
authors.lastname: Bennett
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Watkins
authors.forename: Xi
authors.initials: X
authors.lastname: He
authors.forename: Desmond J
authors.initials: DJ
authors.lastname: Fitzgerald
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Italiano
authors.forename: Patricia B
authors.initials: PB
authors.lastname: Maguire
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000166:cytology; D002460:Cell Line; D002478:Cells, Cultured / Q000187:drug effects; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D008099:Liver / Q000196:embryology; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000172:deficiency / Q000235:genetics; D008533:Megakaryocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011994:Recombinant Proteins / Q000494:pharmacology; D034061:Thrombopoiesis / Q000235:genetics / Q000502:physiology*; D051153:Wnt Proteins / Q000494:pharmacology; D060449:Wnt Signaling Pathway / Q000502:physiology*; D060509:Wnt3A Protein / Q000494:pharmacology; D051176:beta Catenin / Q000096:biosynthesis / Q000235:genetics
chemical_list: C495270:CTNNB1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D060488:Low Density Lipoprotein Receptor-Related Protein-6; C555476:Lrp6 protein, mouse; D011994:Recombinant Proteins; D051153:Wnt Proteins; D060509:Wnt3A Protein; D051176:beta Catenin