Developmental impairments of craniofacial bone and cartilage in transgenic mice expressing FGF10

Hirotaka Yoshioka; Kazuko Kagawa; Tomoko Minamizaki; Masashi Nakano; Jane E Aubin; Katsuyuki Kozai; Kazuhiro Tsuga; Yuji Yoshiko

doi:10.1016/j.bonr.2023.101692

Developmental impairments of craniofacial bone and cartilage in transgenic mice expressing FGF10

Bone Rep. 2023 May 26:18:101692. doi: 10.1016/j.bonr.2023.101692. eCollection 2023 Jun.

Authors

Hirotaka Yoshioka^{1

2}, Kazuko Kagawa^{2

3}, Tomoko Minamizaki², Masashi Nakano^{2

4}, Jane E Aubin⁵, Katsuyuki Kozai⁶, Kazuhiro Tsuga³, Yuji Yoshiko²

Affiliations

¹ Department of Anatomy, School of Medicine, International University of Health and Welfare, Chiba, Japan.
² Department of Calcified Tissue Biology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
³ Department of Advanced Prosthodontics, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
⁴ Department of Pediatric Dentistry, Division of Oral Health and Development, Hiroshima University Hospital, Hiroshima, Japan.
⁵ Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
⁶ Department of Pediatric Dentistry, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.

Abstract

Mutations in a common extracellular domain of fibroblast growth factor receptor (FGFR)-2 isoforms (type IIIb and IIIc) cause craniosynostosis syndrome and chondrodysplasia syndrome. FGF10, a major ligand for FGFR2-IIIb and FGFR1-IIIb, is a key participant in the epithelial-mesenchymal interactions required for morphogenetic events. FGF10 also regulates preadipocyte differentiation and early chondrogenesis in vitro, suggesting that FGF10-FGFR signaling may be involved in craniofacial skeletogenesis in vivo. To test this hypothesis, we used a tet-on doxycycline-inducible transgenic mouse model (FGF10 Tg) to overexpress Fgf10 from embryonic day 12.5. Fgf10 expression was 73.3-fold higher in FGF10 Tg than in wild-type mice. FGF10 Tg mice exhibited craniofacial anomalies, such as a short rostrum and mandible, an underdeveloped (cleft) palate, and no tympanic ring. Opposite effects on chondrogenesis in different anatomical regions were seen, e.g., hyperplasia in the nasal septum and hypoplasia in the mandibular condyle. We found an alternative splicing variant of Fgfr2-IIIb with a predicted translation product lacking the transmembrane domain, and suggesting a soluble form of FGFR2-IIIb (sFGFR2-IIIb), differentially expressed in some of the craniofacial bones and cartilages. Thus, excessive FGF10 may perturb signal transduction of the FGF-FGFR, leading to craniofacial skeletal abnormalities in FGF10 Tg mice.

Keywords: Chondrogenesis; Craniofacial skeleton; FGF10; FGFR2.