Effects of recombinant human syntaxin-4(STX4) on lipopolysaccharide-induced islet β-cell INS-1 injury and underlying mechanism / 中华内分泌代谢杂志

ABSTRACT

Objective:To explore the effect of recombinant human syntaxin-4(STX4) on lipopolysaccharide(LPS)-induced injury in islet β-cells(INS-1).Methods:Pancreatic islet β-cells(INS-1) were divided into Control (blank control), LPS (LPS treatment), LPS+ NC (transfection of negative control vector, LPS treatment), and LPS+ STX4 (transfection of pcDNA-STX4, LPS treatment) groups. RT-qPCR and Western blot were used to detect STX4 mRNA and protein expression, flow cytometry to detect apoptosis, DCFHDA method to detect reactive oxygen species(ROS) level, xanthine oxidation method to detect superoxide orgotein dismutase(SOD) level, colorimetric method to detect glutathione peroxidase(GSH-Px) level, ammonium molybdate colorimetric method to detect catalase(CAT) level, thiobarbituric acid method to detect malonaldehyde(MDA) level, ELISA method to detect the level of interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α), and insulin secretion levels under glucose conditions secreted by cells, Western blot method to detect Cleared Caspase-3, Bcl-2 Associated X Protein(Bax), p65 protein expression. After treatment with NF-κB signaling pathway activator, STX4 up-regulated islet β-cell INS-1 was given LPS stimulation, and the same method was used to measure apoptosis, ROS, SOD, GSH-Px, CAT, MDA levels and secreted IL-1β, TNF-α, insulin levels and Cleaved Caspase-3, Bax, p65 protein levels.Results:Compared with the Control group, the expression of STX4 mRNA and protein in islet β cells of the LPS group decreased, the apoptosis rate, ROS level, and MDA levels increased, and the levels of SOD, GSH-Px, and CAT decreased, the levels of IL-1β, TNF-α increased, the level of insulin secreted by the cells decreased, and the expression levels of Cleaved Caspase-3, Bax, and p65 also increased. NF-κB pathway activator treatment reversed the effect of up-regulated STX4 on islet β-cell apoptosis, ROS, SOD, GSH-Px, CAT, MDA levels and secreted IL-1β, TNF-α levels, and Cleaved Caspase-3 , Bax and p65 protein levels.Conclusion:Up-regulation of STX4 alleviated LPS-induced islet β cell oxidative damage, apoptosis and inflammatory factor release. The underlying mechanism might be related to the inhibition of activated NF-κB signaling pathway.