Targeting SLK protects against cerebral ischemia–reperfusion injury by regulating USP8-mediated HIF-1α stabilization and RhoA/ROCK activation

INTRODUCTION: Acute ischemic stroke (AIS) represents a major global contributor to mortality and chronic disability, with few effective therapeutic targets available. Identifying druggable genes associated with AIS is therefore critical for developing novel interventions. METHODS: A comprehensive approach combining Mendelian randomization, multi-omics integration, and machine learning was employed to identify candidate druggable genes. Causal relationships were confirmed through genetic colocalization, and candidate genes were further validated in a retrospective clinical cohort comprising 60 patients who experienced AIS and 30 healthy controls. Functional and mechanistic investigations were performed using a male mouse middle cerebral artery occlusion/reperfusion (MCAO/R) model, oxygen-glucose deprivation/reperfusion (OGD/R) in HT22 cells, and 293 T cells. RESULTS: SLK emerged as a genetically causal AIS gene and a central component of the optimal predictive model. Plasma SLK levels were elevated in patients who experienced AIS, demonstrating strong diagnostic and prognostic value and serving as an independent predictor of unfavorable 3-month outcomes after adjusting for age, sex, and baseline National Institutes of Health Stroke Scale (NIHSS) score. Knockdown of SLK conferred neuroprotection both in vivo and in vitro. SLK interacted with and phosphorylated the deubiquitinase USP8, increasing its activity and suppressing K48-linked polyubiquitination and degradation of HIF-1α. HIF-1α was stabilized following activation of the RhoA/ROCK signaling pathway, aggravating ischemic injury, whereas USP8 overexpression mitigated the neuroprotective effects of SLK knockdown. CONCLUSIONS: These findings identify SLK as a neuron-specific proischemic factor and a potential therapeutic target, elucidate the SLK-USP8-HIF-1α-RhoA/ROCK pathway as a key mechanistic pathway, and highlight plasma SLK as a promising diagnostic and prognostic biomarker with translational relevance.