title: Expression of the Wnt inhibitor Dickkopf-1 is required for the induction of neural markers in mouse embryonic stem cells differentiating in response to retinoic acid.
abstract: Cultured mouse D3 embryonic stem (ES) cells differentiating into embryoid bodies (EBs) expressed several Wnt isoforms, nearly all isotypes of the Wnt receptor Frizzled and the Wnt/Dickkopf (Dkk) co-receptor low-density lipoprotein receptor-related protein (LRP) type 5. A 4-day treatment with retinoic acid (RA), which promoted neural differentiation of EBs, substantially increased the expression of the Wnt antagonist Dkk-1, and induced the synthesis of the Wnt/Dkk-1 co-receptor LRP6. Recombinant Dkk-1 applied to EBs behaved like RA in inducing the expression of the neural markers nestin and distal-less homeobox gene (Dlx-2). Recombinant Dkk-1 was able to inhibit the Wnt pathway, as shown by a reduction in nuclear beta-catenin levels. Remarkably, the antisense- or small interfering RNA-induced knockdown of Dkk-1 largely reduced the expression of Dlx-2, and the neuronal marker beta-III tubulin in EBs exposed to RA. These data suggest that induction of Dkk-1 and the ensuing inhibition of the canonical Wnt pathway is required for neural differentiation of ES cells.
authors.affiliation: Department of Human Physiology and Pharmacology, University of Rome La Sapienza, Rome, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Verani
authors.forename: I
authors.initials: I
authors.lastname: Cappuccio
authors.forename: P
authors.initials: P
authors.lastname: Spinsanti
authors.forename: R
authors.initials: R
authors.lastname: Gradini
authors.forename: A
authors.initials: A
authors.lastname: Caruso
authors.forename: M C
authors.initials: MC
authors.lastname: Magnotti
authors.forename: M
authors.initials: M
authors.lastname: Motolese
authors.forename: F
authors.initials: F
authors.lastname: Nicoletti
authors.forename: D
authors.initials: D
authors.lastname: Melchiorri
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004622:Embryo, Mammalian; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D007150:Immunohistochemistry / Q000379:methods; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009474:Neurons / Q000378:metabolism*; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects*; D014162:Transfection / Q000379:methods; D014212:Tretinoin / Q000494:pharmacology*; D051153:Wnt Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C501127:Dkk1 protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051153:Wnt Proteins; D014212:Tretinoin