title: WNT signals are required for the initiation of hair follicle development.
abstract: Hair follicle morphogenesis is initiated by a dermal signal that induces the development of placodes in the overlying epithelium. To determine whether WNT signals are required for initiation of follicular development, we ectopically expressed Dickkopf 1, a potent diffusible inhibitor of WNT action, in the skin of transgenic mice. This produced a complete failure of placode formation prior to morphological or molecular signs of differentiation, and blocked tooth and mammary gland development before the bud stage. This phenotype indicates that activation of WNT signaling in the skin precedes, and is required for, localized expression of regulatory genes and initiation of hair follicle placode formation.
authors.affiliation: Department of Dermatology, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Andl
authors.forename: Seshamma T
authors.initials: ST
authors.lastname: Reddy
authors.forename: Trivikram
authors.initials: T
authors.lastname: Gaddapara
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Millar
mesh_terms: D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002455:Cell Division; D003598:Cytoskeletal Proteins / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D053339:Edar Receptor; D000078404:Epidermal Cells; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006197:Hair / Q000002:abnormalities; D018859:Hair Follicle / Q000002:abnormalities / Q000254:growth & development*; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; D008321:Mammary Glands, Animal / Q000002:abnormalities; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010641:Phenotype; D011506:Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D053338:Receptors, Ectodysplasin; D018124:Receptors, Tumor Necrosis Factor; D015398:Signal Transduction; D012879:Skin Physiological Phenomena; D014071:Tooth Abnormalities / Q000235:genetics; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics; D015854:Up-Regulation; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin
chemical_list: C495267:CTNNB1 protein, mouse; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; C501127:Dkk1 protein, mouse; D053339:Edar Receptor; C506009:Edar protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; D008565:Membrane Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D053338:Receptors, Ectodysplasin; D018124:Receptors, Tumor Necrosis Factor; D015534:Trans-Activators; D014157:Transcription Factors; D051153:Wnt Proteins; C102068:Wnt10b protein, mouse; D029961:Zebrafish Proteins; D051176:beta Catenin; C501128:dkk1b protein, zebrafish