UCP2 protects against intracerebral hemorrhage-induced ferroptosis via suppression of TRIM21-dependent GPX4

Intracerebral hemorrhage (ICH) is characterised by acute onset, rapid progression, and high mortality and disability rates. Ferroptosis is closely related to ICH injury. However, the exact aetiology of ICH-induced brain injury remains unclear. Uncoupling protein 2 (UCP2), an inner mitochondrial membrane protein, exhibits neuroprotective effects against ICH-induced brain injury as well as reduces oxidative stress and ROS in multiple tissues. Therefore, we aimed to elucidate the mechanisms by which UCP2 is involved in ICH-induced ferroptosis using a hemin-induced in vitro rat astrocyte (AST) model. We investigated the morphological and biochemical characteristics of hemin-exposed cultured ASTs, as well as quantified UCP2 expression. UCP2 knockdown-induced alteration in cell death and ferroptosis indices were monitored. Critically, we identified that UCP2 mitigates ferroptosis by suppressing TRIM21-mediated ubiquitination of glutathione peroxidase 4 (GPX4). We observed significantly decreased cell viability, typical ferroptosis-related morphological changes, significantly increased lipid peroxidation products malondialdehyde (MDA) and lipid ROS, and significantly decreased glutathione (GSH) expression in our in vitro hemin-induced intracerebral hemorrhage model. UCP2 expression was significantly upregulated. Mechanistically, UCP2 inhibited TRIM21 E3 ligase activity, thereby blocking GPX4 ubiquitination and degradation, which preserved cellular antioxidant capacity. Collectively, we observed the occurrence of ferroptosis and enhanced UCP2 expression in our in vitro ICH model. UCP2 knockdown aggravated the hemin-induced cell death and increased the ferroptosis sensitivity concomitant with enhanced TRIM21-dependent GPX4 ubiquitination.