Osteoporosis, which is caused by an imbalance in osteoblasts and osteoclasts, is a global age-related metabolic disease. Osteoblasts induce osteocyte and bone matrix formation, while osteoclasts play an important role in bone resorption. Maintaining a balance between osteoblast formation and osteoclastic absorption is crucial for bone remodeling. Circular RNAs (circRNAs), which are characterized by closed-loop structures, are a class of novel endogenous transcripts with limited protein-coding abilities. Accumulating evidence indicates that circRNAs play important roles in various bone diseases, such as osteosarcoma, osteoarthritis, osteonecrosis, and osteoporosis.
Fig: Schematic diagram of classifications of circRNAs: According to the biogenesis characteristics from genomic regions, circRNAs are often divided into four types, ecircRNA, EIcircRNA, intergenic circRNAs, and ciRNA. ecircRNA exon circRNAs, EIcircRNA exon–intron circRNAs, ciRNA circular intronic RNA.
Recent studies have shown that circRNAs regulate osteoblast and osteoclast differentiation and may be potential biomarkers for osteoporosis. In the current review, we summarize the expression, function, and working mechanisms of circRNAs involved in osteoblasts, osteoclast differentiation, and osteoporosis.
Luo, Y., Qiu, G., Liu, Y. et al. Circular RNAs in osteoporosis: expression, functions and roles. Cell Death Discov. 7, 231 (2021). https://doi.org/10.1038/s41420-021-00624-8