Nat10-mediated N4-acetylcytidine modification enhances Nfatc1 translation to exacerbate osteoclastogenesis in postmenopausal osteoporosis.

Increased differentiation or activity of osteoclasts is the key pathogenic factor of postmenopausal osteoporosis (PMOP). N4-acetylcytidine (ac4C) modification, catalyzed by Nat10, is a novel posttranscriptional mRNA modification related to many diseases. However, its impact on regulating osteoclast activation in PMOP remains uncertain. Here, we initially observed that Nat10-mediated ac4C positively correlates with osteoclast differentiation of monocytes and low bone mass in PMOP. The specific knockout of Nat10 in monocytes and remodelin, a Nat10 inhibitor, alleviates ovariectomized (OVX)-induced bone loss by downregulating osteoclast differentiation. Mechanistically, epitranscriptomic analyses reveal that the nuclear factor of activated T cells cytoplasmic 1 (Nfatc1) is the key downstream target of ac4C modification during osteoclast differentiation. Subsequently, translatomic results demonstrate that Nat10-mediated ac4C enhances the translation efficiency (TE) of Nfatc1, thereby inducing Nfatc1 expression and consequent osteoclast maturation. Cumulatively, these findings reveal the promotive role of Nat10 in osteoclast differentiation and PMOP from a novel field of RNA modifications and suggest that Nat10 can be a target of epigenetic therapy for preventing bone loss in PMOP.