Chondrocyte-Specific Inhibition of β-Catenin Signaling Leads to Dysplasia of the Caudal Vertebrae in Mice

STUDY DESIGN. To inhibit β-catenin specifically signaling in chondrocytes Col2-ICAT transgenic mice were generated. Anomalies in caudal vertebrae were detected during embryonic and postnatal stages of Col2-ICAT transgenic mice. OBJECTIVE. To determine the role of canonical β-catenin signaling in caudal vertebral development. SUMMARY OF BACKGROUND DATA. β-catenin signaling plays a critical role in skeletal development. Col2-ICAT transgenic mice were generated to selectively block β-catenin signaling by overexpression of the ICAT gene in chondrocytes. METHODS. Tails of E16.5 transgenic embryos and adult Col2-ICAT transgenic mice and their wild-type littermates were collected and analyzed. Skeletal preparation, 3-dimensional micro-computed tomographic and histological analyses were performed to evaluate changes in the structure of caudal vertebrae. Bromodeoxyuridine labeling was performed to evaluate changes in chondrocyte proliferation in caudal vertebrae. RESULTS. Skeletal preparation and 3-dimensional micro-computed tomographic analyses revealed bone deformation and angulated deformities in tail tissue in Col2-ICAT transgenic mice. Histological studies revealed abnormal bone development and dysplastic caudal vertebrae in Col2-ICAT transgenic mice. Inhibition of β-catenin signaling in cartilage resulted in vertebral dysplasia leading to aberrant resegmenting process. Thus, 2 poorly developed sclerotomes failed to fuse to form a complete vertebrae. BrdU labeling revealed a decreased chondrocyte proliferation in both cartilageous templates of transgenic embryos and the growth plate of adult Col2-ICAT transgenic mice. CONCLUSION. Wnt/β-catenin signaling plays an important role in vertebral development. Inhibition of β-catenin signaling in chondrocytes results in caudal vertebra deformity in mice, which may occur as early as in the stage of sclerotome formation. Level of Evidence: N/A