The role of PSMB5 in sodium arsenite-induced oxidative stress in L-02 cells.

Endemic arsenism is widely distributed in the world, which can damage multiple organs, especially in skin and liver. The etiology is clear, but the mechanisms involved remain unknown. Ubiquitin-proteasome pathway (UPP) is the main pathway regulating protein degradation of which proteasome subunit beta type-5(PSMB5) plays a dominant role. This paper aims to study the role and mechanism of PSMB5 in sodium arsenite (NaAsO)-induced oxidative stress liver injury in L-02 cells. Firstly, L-02 cells were exposed to different concentrations of NaAsO to establish a liver injury model of oxidative stress, and then mechanisms of oxidative stress were studied with carbobenzoxyl-leucyl-leucl-leucll-line (MG132) and knockdown PSMB5 (PSMB5-siRNA). The oxidative stress indicators, levels of 20S proteasome, the transcription and protein expression levels of PSMB5, Cu-Zn superoxide dismutase (SOD1), and glutathione peroxidase 1 (GPx1) were detected. The results demonstrated that NaAsO could induce oxidative stress-induced liver injury and the activity of 20S proteasome and the protein expression of PSMB5, SOD1, and GPx1 decreased. After MG132 or PSMB5-siRNA pretreatment, the gene expression of PSMB decreased. After MG132 or PSMB5-siRNA pretreatment, and then L-02 cells were treated with NaAsO, the gene expression of PSMB remarkably decreased; however, the protein expression of SOD1 and GPx1 increased. Overall, NaAsO exposure could induce oxidative stress liver injury and low expression of PSMB5 in L-02 cells, and PSMB5 might play an important role in the regulation of oxidative stress by regulating the expression of SOD1 and Gpx1.