Epitranscriptomic Regulation of Osteoblast Function: Unveiling the Role of METTL3 and the m6A/YTHDF3/SOX4 Signaling Axis

Abstract

AbstractOsteoblasts, the primary cells responsible for bone formation, play a crucial role in synthesizing the collagen matrix and mineralizing the bone matrix. N6-methyladenosine (m6A) has been closely associated with the osteogenic function of osteoblasts. This study focused on exploring the underlying mechanisms of osteogenesis influenced by methyltransferase like-3 (METTL3) and its target genes. The conditional knockout of METTL3 in osteoblasts hinders their proliferation and differentiation into bone-forming cells, as revealed by our findings. Through meRIP-seq and functional analyses, we confirm the involvement of the key transcription factor, SRY-box 4 (SOX4), in m6A-mediated regulation of cell proliferation and differentiation during osteogenesis. Furthermore, we demonstrate that the reader protein YTH N6-methyladenosine RNA binding protein 3 (YTHDF3) enhances the stability of SOX4 mRNA by recognizing the methylation modification catalyzed by METTL3. Moreover, the overexpression of SOX4 in mice protects against osteoporosis induced by estrogen deficiency. Mechanistically, we have identified the m6A/YTHDF3/SOX4 signaling axis as a pivotal downstream pathway responsible for regulating m6A in osteoblasts. Our results establish that METTL3 promotes osteoblast proliferation and differentiation through the m6A/YTHDF3/SOX4 signaling axis, revealing novel epitranscriptomic mechanisms relevant to skeletal health and diseases.