Stroke is the second leading cause of death worldwide,and oxidative stress plays a crucial role.Celastrol exhibits strong antioxidant properties in several diseases;however,whether it can affect oxidation in cerebral ischemic-reperfusion injury(CIRI)remains unclear.This study aimed to determine whether celastrol could reduce oxidative damage during CIRI and to elucidate the underlying mechanisms.Here,we found that celastrol attenuated oxidative injury in CIRI by upregulating nuclear factor E2-related factor 2(Nrf2).Using alkynyl-tagged celastrol and liquid chromatography-tandem mass spectrometry,we showed that celastrol directly bound to neuronally expressed developmentally downregulated 4(Nedd4)and then released Nrf2 from Nedd4 in astrocytes.Nedd4 promoted the degradation of Nrf2 through K48-linked ubiquitination and thus contributed to astrocytic reactive oxygen species production in CIRI,which was significantly blocked by celastrol.Furthermore,by inhibiting oxidative stress and astrocyte activation,celastrol effectively rescued neurons from axon damage and apoptosis.Our study uncovered Nedd4 as a direct target of celastrol,and that celastrol exerts an antioxidative effect on as-trocytes by inhibiting the interaction between Nedd4 and Nrf2 and reducing Nrf2 degradation in CIRI.

Objective To isolate E.scherichia coli-specific bacteriophages from hospital waste water,analyze their biological character-istics and detect their cleavage effects on bacterial biofilms.Methods The phages were isolated and purified by double-layer agar plate method and their morphology was observed by transmission electron microscopy.Their one-step growth curve,in vitro lysis curve,tem-perature and acid-base stability were determined.Whole genome sequencing was used to analyze the genome composition and character-istics of bacteriophages.The crystal violet staining was used to evaluate the scavenging effects of phage on host biofilms.Results A novel Escherichia coli-specific bacteriophage named vB_EcoP-R1 was isolated from hospital sewage.Transmission electron microscopy revealed that the morphology of vB_EcoP-R1 was similar to that of Podoviridae,a member of Caudovirales,and it could survive stably in the temperature range of-20 ℃ to 50 ℃ and pH 5.0 to 11.0.The total length of the vB_EcoP-R1 genome was 40 875 bp and the GC content was 49.94％.There were no virulence genes and drug resistance genes in the phage genome.vB_EcoP-R1 was capable of lysing clinically isolated Escherichia coli and showed high species and genus specificity.After the phage acted on the host bacteria preformed biofilm for 4 h,the clearance rate of the biofilm reached 80.16％.Conclusion vB_EcoP-R1 should be a novel Escherichia coli-specif-ic bacteriophage with strong lysis and high specificity for species and genus.The bacteriophage could lyse the biofilm formed by the host bacteria,and is expected to be used as an alternative treatment for Escherichia coli infection.