USP7 regulates neuroinflammation and seizure activity through NLRP6 ubiquitination in temporal lobe epilepsy

Epilepsy is a severe neurological disorder characterized by recurrent, abnormal neuronal discharges. Emerging evidence has implicated the ubiquitin-proteasome system (UPS) in the pathophysiology of epilepsy. Ubiquitin-specific protease 7 (USP7), a deubiquitinating enzyme, regulates protein stability, inflammatory responses, and apoptosis. The present study aimed to investigate the expression pattern and functional role of USP7 in epilepsy. A temporal lobe epilepsy (TLE) model was established in adult male C57BL/6 mice by intracranial injection of kainic acid (KA) to induce epileptic seizures. Adeno-associated virus (AAV) vectors were stereotactically injected three weeks before KA administration. HEK293T cells were co-transfected with designated plasmids for mechanistic studies. Experimental evaluations included Western blotting, quantitative real-time PCR, video monitoring of seizures, immunofluorescence staining, local field potential recordings, TUNEL staining, Nissl staining, and immunoprecipitation. Our results showed significantly elevated USP7 expression in the hippocampus of the KA-induced TLE model, with prominent localization in neurons. Knockdown of USP7 reduced seizure severity, attenuated neuronal loss, and suppressed neuroinflammation. Mechanistically, USP7 stabilized NLRP6 by cleaving K11-linked polyubiquitin chains at lysine 95 (K95). Notably, NLRP6 overexpression in the setting of USP7 knockdown worsened seizure severity, increased neuronal death, and enhanced neuroinflammatory responses, accompanied by up-regulation of NLRP6 downstream inflammatory mediators. In conclusion, this study uncovers a novel role for USP7 in epilepsy pathogenesis through activation of the NLRP6 inflammasome pathway, highlighting USP7 as a potential therapeutic target for epilepsy.