FABP3 Aggravates Cerebral Ischemia–Reperfusion Injury by Promoting Mitochondrial Lipid Accumulation and Enhancing BAX-Dependent Apoptosis

We previously demonstrated that fatty acid-binding protein 3 (FABP3) is significantly upregulated in ischemic neurons, and its inhibition mitigates ischemic brain injury in mice and attenuates mitochondrial damage under rotenone-induced oxidative stress. These findings suggest a potential role for FABP3 in mitochondrial dysfunction in ischemic neurons, although the underlying mechanism remains unclear. In this study, we further investigated the role of FABP3 in mitochondrial injury and apoptosis in ischemic neurons. Our findings indicated that FABP3 deficiency significantly decreased infarct volume following middle cerebral artery occlusion/reperfusion (MCAO/R) in mice, improved cognitive and spontaneous activity deficits, and suppressed BAX activation and mitochondrial translocation, caspase-3 activation, and cytochrome c release. In HT22 cells subjected to oxygen-glucose deprivation/reoxygenation (OGD/R), FABP3 deficiency increased cell viability, reduced apoptosis, and alleviated the loss of mitochondrial membrane potential. Conversely, FABP3 overexpression further exacerbated mitochondrial dysfunction and apoptosis, effects that were partially reversed by the BAX inhibitor BAI1. Furthermore, FABP3 overexpression promoted abnormal mitochondrial lipid accumulation and increased lipid peroxidation. Both the mitochondria-targeted antioxidant MitoQ and the ferroptosis inhibitor Ferrostatin-1 alleviated FABP3 overexpression-induced mitochondrial damage and apoptotic signaling. Collectively, our findings suggest that FABP3 is an important promoter of cerebral ischemia–reperfusion injury. FABP3 may aggravate ischemic neuronal injury by promoting abnormal mitochondrial lipid accumulation and lipid peroxidation, thereby enhancing BAX-dependent mitochondrial apoptotic signaling. Targeting FABP3 may provide a potential therapeutic strategy for neuroprotection in ischemic stroke.