CRYAB promotes osteogenic differentiation of human bone marrow stem cells via stabilizing β‐catenin and promoting the Wnt signalling

OBJECTIVES: The osteogenesis differentiation of human bone marrow stem cells (BMSCs) is essential for bone formation and bone homeostasis. In this study, we aim to elucidate novel molecular targets for bone metabolism diseases. MATERIALS AND METHODS: The dataset GSE80614 which includes mRNA expression profile during BMSCs osteogenic differentiation was obtained from the GEO database (https://www.ncbi.nlm.nih.gov/geo/). The osteogenic differentiation of BMSCs was measured by ALP staining, AR staining and expression of osteogenic markers in vitro. For in vivo assay, we seeded BMSCs onto beta-tricalcium phosphate (beta-TCP) and transplanted them into muscle pockets of nude mice. Luciferase assay, co-immunoprecipitation assay and in vitro ubiquitination assay were carried out to investigate the molecular mechanism. RESULTS: We found that alpha-B-crystallin (CRYAB) expression was elevated during the process of BMSCs osteogenic differentiation. Further studies showed that upregulation of CRYAB significantly enhanced the osteogenic differentiation, while downregulation of CRYAB suppressed it. CRYAB regulated BMSCs osteogenic differentiation mainly through the canonical Wnt/beta-catenin signalling. In addition, we found that CRYAB could physically interact with beta-catenin and protect it from ubiquitination and degradation, which stabilized beta-catenin and promoted the Wnt signalling. CONCLUSIONS: The present study provides evidences that CRYAB is an important regulator of BMSCs osteogenic differentiation by protecting beta-catenin from ubiquitination and degradation and promoting the Wnt signalling. It may serve as a potential therapeutic target for diseases related to bone metabolism.