title: Notch/Delta4 signaling inhibits human megakaryocytic terminal differentiation.
abstract: The effects of Notch signaling on human megakaryocytic and erythroid differentiation were investigated by exposing human CD34(+) progenitor cells to an immobilized chimeric form of the Notch ligand, Delta-like4 (Dll4Fc). Exposure of human cord blood CD34(+) cells to Dll4Fc induced a modest enhancement of erythroid cell production. Conversely, under megakaryocytic culture conditions, Dll4Fc strongly impaired platelet production by reducing the generation of mature CD41a(+)CD42b(+) megakaryocytes (MKs) and platelet-forming cells. The inhibitory activity of Dll4 on terminal MK differentiation was confirmed by culturing CD34(+) cells onto Dll-4-expressing stroma cells (engineered to express the membrane-anchored form of Dll4). The reduced production of mature CD41a(+)CD42(+) cells was rescued by inhibiting Notch signaling either with the N-N-(3,5-difluorophenacetyl-L-alanyl)-S-phenylglycine t-butyl ester γ-secretase inhibitor or the dominant-negative version of Mastermind. Dll4 impaired the generation of mature CD41a(+)CD42b(+) cells and proplatelet formation without affecting earlier steps of MK differentiation, such as production of megakaryocytic/erythroid progenitors and colony-forming units-MKs. This blockade was accompanied by a modulation of the transcriptional program of megakaryocytic differentiation. All these results indicate that Dll4/Notch signaling inhibits human terminal MK differentiation.
authors.affiliation: Inserm U1009, Villejuif, France.
authors.forename: Sonia
authors.initials: S
authors.lastname: Poirault-Chassac
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Six
authors.forename: Cyril
authors.initials: C
authors.lastname: Catelain
authors.forename: Mélanie
authors.initials: M
authors.lastname: Lavergne
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Villeval
authors.forename: William
authors.initials: W
authors.lastname: Vainchenker
authors.forename: Evelyne
authors.initials: E
authors.lastname: Lauret
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002135:Calcium-Binding Proteins; D002454:Cell Differentiation; D002478:Cells, Cultured; D018920:Coculture Techniques; D015672:Erythroid Precursor Cells / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008533:Megakaryocytes / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D017154:Stromal Cells / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; C424126:DLL4 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D051880:Receptors, Notch