A genetic mouse model mimicking MET related human osteofibrous dysplasia is characterized by delays in fracture repair and defective osteogenesis

• Published in: The FASEB journal 2024-07, Vol.38 (14), p.e23810-n/a
• Main Authors: Hong, Guoju, Xie, William, Ahmed, Kashif, Oborn, Connor, Soltys, Carrie‐lynn, Kannu, Peter
• Format: Article
• Language: English
• Subjects: Animals; Bone Diseases, Developmental - genetics; Bone Diseases, Developmental - pathology; Cell Differentiation; Disease Models, Animal; Fibrous Dysplasia of Bone - genetics; Fibrous Dysplasia of Bone - metabolism; Fibrous Dysplasia of Bone - pathology; fracture; Fracture Healing - genetics; Humans; Male; Met; Mice; Mice, Inbred C57BL; Mutation; Osteoblasts - metabolism; Osteoblasts - pathology; osteofibrous dysplasia; osteogenesis; Osteogenesis - genetics; Proto-Oncogene Proteins c-met - genetics; Proto-Oncogene Proteins c-met - metabolism; RNA‐seq
• ISSN: 0892-6638; 1530-6860; 1530-6860
• DOI: 10.1096/fj.202400075RR

Osteofibrous dysplasia (OFD) is a rare, benign, fibro‐osseous lesion that occurs most commonly in the tibia of children. Tibial involvement leads to bowing and predisposes to the development of a fracture which exhibit significantly delayed healing processes, leading to prolonged morbidity. We previously identified gain‐of‐function mutations in the MET gene as a cause for OFD. In our present study, we test the hypothesis that gain‐of‐function MET mutations impair bone repair due to reduced osteoblast differentiation. A heterozygous Met exon 15 skipping (MetΔ15‐HET) mouse was created to imitate the human OFD mutation. The mutation results in aberrant and dysregulation of MET‐related signaling determined by RNA‐seq in the murine osteoblasts extracted from the wide‐type and genetic mice. Although no gross skeletal defects were identified in the mice, fracture repair was delayed in MetΔ15‐HET mice, with decreased bone formation observed 2‐week postfracture. Our data are consistent with a novel role for MET‐mediated signaling regulating osteogenesis. This graphical illustrates the experimental workflow for generating MetΔ15‐HET mice using CRISPR/Cas9. The splice donor sequence of murine Met exon 15 was targeted to generate a model characterized by exon 15 skipping. This exon codes for the Y1003 residue important for regulating receptor ubiquitination. These mice are subjected to various analyses including: A. Skeleton and epiphyseal growth plate evaluation to study skeletal development and growth. B. RNA sequencing (RNA‐seq) of bone marrow stromal cells (BMSCs) to analyze gene expression profiles. C. Histological analysis following tibial fracture to investigate bone healing and regeneration processes. The image highlights the embryonic lethality of MetΔ15‐HET mice, emphasizing the viability and importance of the heterozygous model in studying skeletal and cellular biology.