DNA methylation of noncoding RNAs: new insights into osteogenesis and common bone diseases

Bone diseases such as osteoarthritis, osteoporosis, and bone tumor present a severe public health problem. Osteogenic differentiation is a complex process associated with the differentiation of different cells, which could regulate transcription factors, cytokines, many signaling pathways, noncoding RNAs (ncRNAs), and epigenetic modulation. DNA methylation is a kind of stable epigenetic alterations in CpG islands without DNA sequence changes and is involved in cancer and other diseases, including bone development and homeostasis. ncRNAs can perform their crucial biological functions at the RNA level, and many findings have demonstrated essential functions of ncRNAs in osteogenic differentiation. In this review, we highlight current researches in DNA methylation of two relevant ncRNAs, including microRNAs and long noncoding RNAs, in the initiation and progression of osteogenesis and bone diseases.