title: Muenke syndrome mutation, FgfR3P²⁴⁴R, causes TMJ defects.
abstract: Muenke syndrome is characterized by various craniofacial deformities and is caused by an autosomal-dominant activating mutation in fibroblast growth factor receptor 3 (FGFR3(P250R)               ). Here, using mice carrying a corresponding mutation (FgfR3(P244R)               ), we determined whether the mutation affects temporomandibular joint (TMJ) development and growth. In situ hybridization showed that FgfR3 was expressed in condylar chondroprogenitors and maturing chondrocytes that also expressed the Indian hedgehog (Ihh) receptor and transcriptional target Patched 1(Ptch1). In FgfR3(P244R)                mutants, the condyles displayed reduced levels of Ihh expression, H4C-positive proliferating chondroprogenitors, and collagen type II- and type X-expressing chondrocytes. Primary bone spongiosa formation was also disturbed and was accompanied by increased osteoclastic activity and reduced trabecular bone formation. Treatment of wild-type condylar explants with recombinant FGF2/FGF9 decreased Ptch1 and PTHrP expression in superficial/polymorphic layers and proliferation in chondroprogenitors. We also observed early degenerative changes of condylar articular cartilage, abnormal development of the articular eminence/glenoid fossa in the TMJ, and fusion of the articular disc. Analysis of our data indicates that the activating FgfR3(P244R)                mutation disturbs TMJ developmental processes, likely by reducing hedgehog signaling and endochondral ossification. We suggest that a balance between FGF and hedgehog signaling pathways is critical for the integrity of TMJ development and for the maintenance of cellular organization.
authors.affiliation: Division of Orthopaedic Surgery, The Children's Hospital of Philadelphia, Abramson Research Center, 3516 Civic Center Blvd, Philadelphia, PA 19107, USA.
authors.forename: T
authors.initials: T
authors.lastname: Yasuda
authors.forename: H D
authors.initials: HD
authors.lastname: Nah
authors.forename: J
authors.initials: J
authors.lastname: Laurita
authors.forename: T
authors.initials: T
authors.lastname: Kinumatsu
authors.forename: Y
authors.initials: Y
authors.lastname: Shibukawa
authors.forename: T
authors.initials: T
authors.lastname: Shibutani
authors.forename: N
authors.initials: N
authors.lastname: Minugh-Purvis
authors.forename: M
authors.initials: M
authors.lastname: Pacifici
authors.forename: E
authors.initials: E
authors.lastname: Koyama
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000002:abnormalities; D020219:Chondrogenesis / Q000235:genetics; D003398:Craniosynostoses / Q000235:genetics* / Q000473:pathology; D005346:Fibroblast Growth Factors / Q000502:physiology*; D055879:Gene Knock-In Techniques; D053823:Hedgehog Proteins / Q000502:physiology; D008335:Mandibular Condyle / Q000002:abnormalities*; D051379:Mice; D008817:Mice, Mutant Strains; D009154:Mutation; D010012:Osteogenesis / Q000235:genetics; D051498:Receptor, Fibroblast Growth Factor, Type 3 / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics; D013701:Temporal Bone / Q000002:abnormalities; D013704:Temporomandibular Joint / Q000002:abnormalities*
chemical_list: D053823:Hedgehog Proteins; C514061:ihh protein, mouse; D005346:Fibroblast Growth Factors; C496366:Fgfr3 protein, mouse; D051498:Receptor, Fibroblast Growth Factor, Type 3