Glutathione peroxidase 4 deficit-mediated fer⁃roptosis contributes to dopaminergic neuron degeneration under synucleinopathy

摘要

OBJECTIVE Intracellular aggre⁃gation ofα-synuclein(SNCA)is one of the core pathological features of neurodegenerative disor⁃ders including Parkinson disease,whilst the detailed mechanism for consequently neuron loss has not been fully illustrated.Since the altered phospholipid homeostasis has been suggested to play a role in synucleinopathy,this study aims to depict the fully-featured status of phospholip⁃ids and the targets reposingα-synuclein-related neurotoxicity.METHODS SNCAA53T transgenic mice were utilized as the model of Parkinson disease.Behavioral tests including pole test,rotarod test and gait analysis were conducted to assess the motor features of Parkinsonism.Tyro⁃sine hydroxylase were determined by immunohis⁃tochemistry.Glutathione,dopamine,3,4-dihy⁃droxyphenylacetic acid and homovanillic acid were determined by HPLC-ECD analysis.Assess⁃ment of lipid peroxidation included MDA assay and Liperfluo staining.Phospholipid-omics was analyzed based on LC-MS/MS.Investigation on mechanism was relied on Western blotting and qPCR assay.The injection of AAV into midbrain was achieved by ultra-micro injection pump to obtain the target genotype.RESULTS SNCAA53T transgenic mice displayed progres⁃sively deteriorated motor coordination functions and the mechanisms were related with lipid per⁃oxidation and ferroptosis,which might help to explain the parkinsonism.These hydroperoxides were observed on plasm membrane and were further characterized by LC-MS/MS-based phos⁃pholipid-omics analysis.α-synucleinA53T trans⁃genic mice displayed distinct patterns of phos⁃pholipid peroxidation in midbrain regions com⁃pared to wild type littermates.Among different subtypes of oxidized phospholipids,oxidative phosphatidylcholine(PC-ox)was more promi⁃nently elevated.Phospholipid peroxidation is believed as a biomarker of ferroptosis,which is largely a specialized death program caused by insufficiency of glutathione peroxidase-4(GPX4),the only known enzyme that can reduce lipid hydroperoxides within biological membranes.The deficiency of Gpx4 was demonstrated to be responsible forα-synuclein-induced lipid peroxi⁃dation,and the cell lines and mouse models underwent genetic Gpx4 downregulation showed exacerbated dopaminergic neuron loss and par⁃kinsonism.On the other hand,the potentiation of Gpx4 expression remarkably inhibited dopami⁃nergic ferroptotic death and behavioral deficits in a mouse model with synucleinopathy.CONCLU⁃SION A cellular pathway that Gpx4 deficit-medi⁃ated phospholipid peroxidation and behavioral consequence participated in synucleinopathy,suggesting a potential strategy targeting Gpx4 to alleviate PD symptoms.