Hypoxia-Induced Lactylation of NSUN3 Promotes m5C Methylation of SETD2 to Regulate Peripheral Nerve Injury Repair.

BACKGROUND: Peripheral nerve injury (PNI) repair remains challenging, with metabolic regulation and neuronal senescence playing critical roles. This study explored whether intermittent hypoxia modulates injured dorsal root ganglion (DRG) neuron regeneration via lactate-mediated mechanisms. METHODS: DRG neurons were subjected to impairment via acrylamide (ACR) to develop an in vitro injury model, followed by the induction of intermittent hypoxia and lactate production inhibitors including 2-deoxy-d-glucose (2-DG) and oxamate. In vivo experiments employed a rat PNI model exposed to intermittent hypoxia. Cellular evaluations comprised the CCK-8 assay to determine cell viability, β-galactosidase staining to identify cellular senescence, and immunofluorescence for the detection of p21 and Lamin B1. The m5C-RIP-qPCR assay was used to assess m5C modification of SETD2 mRNA. The immunoprecipitation was applied to examine the lactylation of NSUN3 protein. RESULTS: Intermittent hypoxia increased lactate production, improved ACR-impaired DRG viability, reduced ROS and MDA levels, and promoted damaged neuron regeneration, effects reversed by 2-DG or oxamate. Hypoxia inhibited ACR-induced neuron senescence, which was abrogated by lactate inhibitors. Mechanistically, hypoxia-induced lactate promoted NSUN3 lactylation, further enhanced m5C modification and stability of SETD2 mRNA. NSUN3 knockdown exacerbated senescence and suppressed mitochondrial biogenesis, while SETD2 overexpression reversed these impacts. CONCLUSION: Intermittent hypoxia facilitated the regeneration of injured DRG neurons through lactate-mediated NSUN3 lactylation. This process was correlated with the stability of SETD2 mRNA via m5C modification, thereby mitigating cellular senescence and promoting mitochondrial function. These findings present novel targets for strategies aimed at nerve repair.