The Role of G-Protein-Coupled Receptor Kinase 4 in Modulating Mitophagy and Oxidative Stress in Cerebral Ischemia-Reperfusion Injury.

Cerebral ischemia-reperfusion injury (CIRI) causes significant neuronal damage through oxidative stress, inflammation, and mitochondrial dysfunction. The G-protein-coupled receptor kinase 4 (GRK4) has been implicated in regulating stress responses in various tissues, but its role in ischemic brain injury remains unclear. In this study, we investigated the role of GRK4 in oxidative stress, inflammation, and mitophagy during CIRI using both in vivo and in vitro models. For the in vivo experiments, we employed the bilateral common carotid artery occlusion (BCCAO) model to induce ischemia-reperfusion injury. Our finding demonstrated that ischemic reperfusion significantly upregulated GRK4 expression in the brain, correlating with elevated levels of inflammatory cytokines and oxidative stress markers. In cultured cerebellar neurons subjected to oxygen-glucose deprivation (OGD), over-expression of GRK4 decreased cell viability, while GRK4 inhibition enhanced neuronal survival, suggesting that GRK4 exacerbates neuronal damage in ischemic conditions. Furthermore, GRK4 overexpression impaired mitophagy, as indicated by altered expression of key mitophagy-related proteins (Beclin-1, PINK1, and p62), which led to mitochondrial dysfunction and increased oxidative stress. In contrast, GRK4 inhibition promoted more efficient mitophagy and improved mitochondrial quality control. These results highlight the detrimental role of GRK4 in ischemic brain injury and suggest that targeting GRK4 could offer a novel therapeutic strategy to mitigate neuronal damage by balancing oxidative stress, inflammation, and mitochondrial dynamics. Further studies are needed to elucidate the precise molecular mechanisms underlying GRK4-mediated neuroinflammation and mitochondrial dysfunction in ischemic stroke.