Alteration of Ubiquitination in the Brain of ENOPH1 Knockout Mice after Early Ischemic Stroke

Enolase-phosphatase 1 (ENOPH1) is a newly identified enzyme associated with stress responses and neurodevelopmental disorders. Our previous study found that ENOPH1 mediates cerebral cell apoptosis and blood-brain barrier (BBB) dysfunction during early cerebral ischemia. Ubiquitination has been identified in neuronal damage and the neuroinflammatory response in ischemic stroke. However, whether ENOPH1 regulates ischemia-induced protein ubiquitination alteration is yet unclear. Hence, the present study explored changes in the ubiquitinomic in early ischemic brain tissues between wildtype and ENOPH1 knockout mice using a comprehensive quantitative analysis. Our results showed that 4000 ubiquitination-modified sites in 1613 proteins were quantified, with 772 ubiquitinated sites in 464 proteins significantly decreasing or increasing after ENOPH1 knockout (fold change >1.5 or <1/1.5, p < 0.05). When compared to our previous parallel proteome profiles, common differential proteins FKBP5 and Claudin-11 were observed and further validated. ENOPH1 regulates the degradation of FKBP5 and the promotion of Claudin-11 by ubiquitination mediation, leading to the activation or inhibition of nuclear-initiated steroid signaling and transendothelial migration pathways. These findings, for the first time, identified ubiquitinomic features of early ischemic brain tissues after ENOPH1 knockout, suggesting that ENOPH1 may regulate neuroinflammatory stress and barrier function by modifying FKBP5 and Claudin-11 protein ubiquitination.