title: Roles for PDGF-A and sonic hedgehog in development of mesenchymal components of the hair follicle.
abstract: Skin appendages, such as hair, develop as a result of complex reciprocal signaling between epithelial and mesenchymal cells. These interactions are not well understood at the molecular level. Platelet-derived growth factor-A (PDGF-A) is expressed in the developing epidermis and hair follicle epithelium, and its receptor PDGF-Ralpha is expressed in associated mesenchymal structures. Here we have characterized the skin and hair phenotypes of mice carrying a null mutation in the PDGF-A gene. Postnatal PDGF-A-/- mice developed thinner dermis, misshapen hair follicles, smaller dermal papillae, abnormal dermal sheaths and thinner hair, compared with wild-type siblings. BrdU labeling showed reduced cell proliferation in the dermis and in the dermal sheaths of PDGF-A-/- skin. PDGF-A-/- skin transplantation to nude mice led to abnormal hair formation, reproducing some of the features of the skin phenotype of PDGF-A-/- mice. Taken together, expression patterns and mutant phenotypes suggest that epidermal PDGF-A has a role in stimulating the proliferation of dermal mesenchymal cells that may contribute to the formation of dermal papillae, mesenchymal sheaths and dermal fibroblasts. Finally, we show that sonic hedgehog (shh)-/- mouse embryos have disrupted formation of dermal papillae. Such embryos fail to form pre-papilla aggregates of postmitotic PDGF-Ralpha-positive cells, suggesting that shh has a critical role in the assembly of the dermal papilla.
authors.affiliation: Department of Medical Biochemistry, Göteborg University, Medicinaregatan 9A, Box 440, SE 405 30 Göteborg, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Karlsson
authors.forename: C
authors.initials: C
authors.lastname: Bondjers
authors.forename: C
authors.initials: C
authors.lastname: Betsholtz
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism; D002455:Cell Division; D020405:Dermis / Q000166:cytology / Q000378:metabolism; D004627:Embryonic Induction / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018859:Hair Follicle / Q000196:embryology* / Q000473:pathology*; D053823:Hedgehog Proteins; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D008819:Mice, Nude; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology; D000072079:Patched Receptors; D010982:Platelet-Derived Growth Factor / Q000235:genetics* / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D020796:Receptor, Platelet-Derived Growth Factor alpha; D011956:Receptors, Cell Surface; D017479:Receptors, Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism; D012867:Skin / Q000196:embryology / Q000378:metabolism / Q000473:pathology; D016038:Skin Transplantation; D015534:Trans-Activators; D016212:Transforming Growth Factor beta
chemical_list: D000199:Actins; C525719:Bmp2 protein, mouse; C525810:Bmp4 protein, mouse; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D053823:Hedgehog Proteins; D008565:Membrane Proteins; D000072079:Patched Receptors; D010982:Platelet-Derived Growth Factor; D011506:Proteins; D011956:Receptors, Cell Surface; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; C075278:platelet-derived growth factor A; D020796:Receptor, Platelet-Derived Growth Factor alpha; D017479:Receptors, Platelet-Derived Growth Factor