ETS transcription factor 1-insulin-like growth factor 2 mRNA-binding protein 2-interferon-induced transmembrane protein 3 pathway promotes ferroptosis-driven osteoblast senescence in diabetic osteoporosis

Type 2 diabetes-associated osteoporosis (T2DOP) is characterized by progressive bone loss under chronic hyperglycemic stress; however, the contribution of Ferroptosis to osteoblast dysfunction remains poorly understood. This study aimed to elucidate the molecular mechanisms driving osteoblast Ferroptosis and senescence in T2DOP and to identify potential epigenetic regulatory targets. A streptozotocin/high-fat diet (STZ/HFD)-induced diabetic osteoporosis mouse model was established and exhibited significantly reduced bone mass. Diabetic femora and primary osteoblasts displayed prominent ferroptotic features, including increased lipid peroxidation and decreased GPX4 expression. Genetic deletion of Ifitm3 markedly alleviated Ferroptosis and reduced cellular senescence (90% decrease in p21 expression). To examine the role of Ifitm3 in DOP, Ifitm3^-/^- and Elf1^-/^- mice were generated for functional assessment, and primary osteoblasts were isolated for in vitro experiments. A comprehensive approach was employed to elucidate the epigenetic and transcriptional regulation of Ifitm3 in DOP, integrating RNA Sequencing (RNA-seq), m6A-MeRIP-seq, and MeRIP-qPCR. Additionally, we employed a variety of techniques, including μCT imaging, immunohistochemistry, immunofluorescence, ChIP-qPCR, dual-luciferase reporter assays, western blotting, and RNA pull-down experiments. Mechanistically, hyperglycemia activated the ETS transcription factor ELF1, which transcriptionally upregulated Igf2bp2, an N6-methyladenosine (m6A) reader protein. Mettl14-mediated m6A modification enhanced Ifitm3 mRNA stability through Igf2bp2 binding, as confirmed by MeRIP-qPCR and RNA decay assays. This Elf1-Igf2bp2-m6A-Ifitm3 cascade amplified lipid peroxidation and mitochondrial dysfunction in osteoblasts. Under the diabetic stress of the DOP model, this signaling axis exacerbated ferroptotic cell death, highlighting the pivotal role of Ifitm3 in mediating osteoblast dysfunction in DOP. Our study uncovers a previously unrecognized epigenetic Ferroptosis pathway-the Elf1-Igf2bp2-m6A-Ifitm3-that critically contributes to osteoblast dysfunction in DOP, offering potential therapeutic targets for mitigating ferroptosis-related bone loss in diabetes. Targeting this signaling axis may offer a novel therapeutic strategy for diabetic osteoporosis.

Ferroptosis; IFITM3; IGF2BP2; N6-methyladenosine modification; Osteoblast; Type 2 diabetes-associated osteoporosis.