NSUN2/ALYREF-medicated m5C-modified circRNA505 regulates the proliferation, differentiation, and glycolysis of antler chondrocytes via the miRNA-127/p53 axis and LDHA.

The deer antler is a fully regenerable and the fastest-growing osseous organ. Circular RNA (circRNA), a novel member of the non-coding RNA family, has significant research potential and crucial roles in biological processes. This study aims to explore the impact and mechanisms of circRNA505 on antler chondrocytes. Functional experiments demonstrated that m5C-modified circRNA505 inhibits antler chondrocyte proliferation, enhances osteogenic differentiation, and facilitates cellular glycolysis. Mechanistically, dual luciferase and AGO2-RIP assays revealed a direct binding relationship between circRNA505, miR-127, and p53. Rescue assays further showed that circRNA505 affects cell proliferation and differentiation through the miR-127/p53 axis. Meanwhile, RNA Antisense Purification (RAP) screening and analysis of related proteins binding to circRNA505 demonstrated that circRNA505 binds to LDHA and increases the level of LDHA phosphorylation through FGFR1 to promote cellular glycolysis by FISH-IF, RIP, and Western blot experiments. Additionally, Me-RIP assays confirmed the m5C methylation modification of circRNA505. NSUN2 mediates the m5C modification of circRNA505, affecting its stability, while the m5C reader ALYREF promotes the nuclear export of circRNA505 in an ALYREF-dependent manner. This study provides new insights into the regulatory mechanisms underlying rapid antler development.