PDK4 suppresses high glucose-induced microglial ferroptosis by restricting pro-ferroptotic PUFA biosynthesis.

Abstract

Background: Diabetes significantly elevates the risk of neurodegenerative disorders, including Alzheimer's disease and Parkinson's disease, indicating shared pathophysiological mechanisms. While ferroptosis is increasingly implicated in neurodegeneration, microglia - highly vulnerable to ferroptosis - may mediate this link. However, it remains unknown whether high glucose (HG) directly induces microglial ferroptosis.

Methods: Using HG-treated BV2 microglia, we integrated multiomics profiling (RNA-seq and targeted lipidomics), functional assays, and genetic manipulation of pyruvate dehydrogenase kinase 4 (PDK4) to investigate its role in HG-associated ferroptosis.

Results: HG-induced microglial ferroptosis, characterized by iron overload, elevated malondialdehyde and mitochondrial reactive oxygen species, glutathione peroxidase 4 (GPX4) downregulation, and mitochondrial damage, including loss of membrane potential and ultrastructural disintegration. This was accompanied by upregulated PDK4 expression. PDK4 overexpression attenuated ferroptosis by preserving GPX4, reducing lipid peroxidation, and maintaining mitochondrial integrity; these protective effects were reversed by n-6 polyunsaturated fatty acid (PUFA) supplementation. Conversely, PDK4 knockdown exacerbated ferroptosis via amplified n-6 PUFA synthesis and oxidative stress. Mechanistically, PDK4 acts as a metabolic gatekeeper by restricting acetyl-CoA availability for the synthesis of pro-ferroptotic PUFAs, thereby curtailing iron-dependent lipid peroxidation.

Conclusion: PDK4 is a critical regulator of HG-induced microglial ferroptosis, thereby bridging hyperglycemia-induced metabolic dysfunction and neurodegeneration. Our findings nominate PDK4 as a promising therapeutic target for diabetes-linked neurodegenerative diseases.