NSUN2 activated by KLF6 can mediate m5C modification of NCOA4 to enhance ferroptosis of OGD/R-induced SH-SY5Y cells in ischemic stroke.

Ischemic stroke (IS) constitutes the majority of stroke cases. Ferroptosis, a non-apoptotic form of programmed cell death, is an essential mechanism of IS. This study aimed to investigate a ferroptosis-related molecular mechanism in IS progression. IS model in vitro was induced by oxygen-glucose deprivation/reoxygenation (OGD/R) in SH-SY5Y cells. RT-qPCR and Western blotting were performed for detection of NOP2/Sun RNA methyltransferase family member 2 (NSUN2), nuclear receptor coactivator 4 (NCOA4), and Krueppel-like factor 6 (KLF6). Cell functions were assessed by MTT assay, flow cytometry, and enzyme-linked immunosorbent assay. Mitochondrial membrane potential and other ferroptosis indicators were examined using kits. Molecular binding was detected using methylated RNA immunoprecipitation (MeRIP), RIP, dual-luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay. IS animal model was established by middle cerebral artery occlusion (MCAO). OGD/R-induced apoptosis, inflammation, and ferroptosis of SH-SY5Y cells were suppressed by NCOA4 knockdown. NSUN2 could promote NCOA4 mRNA stability by mediating 5-methylcytosine (m5C) methylation modification of NCOA4, and YBX1 served as a reader protein. NSUN2 contributed to OGD/R-induced SH-SY5Y cell injury via upregulating NCOA4. KLF6 acted as a transcription factor to activate NSUN2 transcription, and then facilitated nerve injury of OGD/R-induced SH-SY5Y cells. Animal assay showed that silencing NSUN2 inhibited infarct volume, tissue injury, neurological function, and neuroinflammation in MCAO rats. These current findings affirmed that KLF6-activated NSUN2 could contribute to ferroptosis of OGD/R-induced SH-SY5Y cells via inducing NCOA4 m5C modification, providing a novel insight into the mechanism of ferroptosis in IS.