Long noncoding RNA Hottip maintained skeletal homeostasis via suppressing the enhancer of zeste homolog 2 (Ezh2)/histone methylation regulatory axis

Recent evidence suggests that long noncoding RNAs (lncRNAs) play a crucial role in regulating bone remodeling and skeletal homeostasis by coordinating the development of osteoblasts and osteoclasts. Several lncRNAs have been identified to participate in bone formation and resorption processes. Among them, the well-known oncogenic lncRNA, Hottip, has been reported to be involved in osteogenesis regulation. However, the specific function and underlying mechanisms remain poorly understood. In this study, we investigated the role of lncRNA Hottip in bone remodeling and skeletal homeostasis. Hottip knockout mice exhibited disrupted bone metabolism, abnormal bone tissue, and compromised bone quality, resulting in delayed fracture healing. In vitro experiments demonstrated that Hottip knockdown inhibited osteoblast differentiation while promoting osteoclast differentiation, with the opposite effect observed upon Hottip overexpression. Mechanistically, Hottip physically interacted with EZH2, leading to its degradation and facilitating the transcription of osteogenic genes by suppressing H3K9me3 and H3K27me3. In vivo experiments further validated the potential of Hottip overexpression to promote bone regeneration and accelerate fracture healing. In conclusion, our study reveals Hottip as a critical regulator in the differentiation of osteoblasts and osteoclasts, crucial for maintaining skeletal homeostasis. This lncRNA shows potential as a promising therapeutic target for bone regeneration.