The Role Of Parkin In Lipopolysaccharide-Induced Inflammation

The inflammatory response is a pathological process in which the body resists microbial infection,induces the production of a large number of pro-inflammatory factors,activates the transcription factor NF-?B and induces the expression of downstream inflammation-related genes.Lipopolysaccharide(LPS),a component of the cell wall of Gram-negative bacilli,stimulates the body's innate immunity and is a commonly used effective reagent for establishing inflammatory injury models.In this paper,LPS treatment was used to establish an in vitro and in vivo inflammatory model.The effects of inflammation on Parkin protein expression and Parkin's role in inflammation were studied.The anti-inflammatory effects of Parkin were explored.In this experiment,LPS-induced tumor cells HL-60 and MGC-823 were used to establish an in vitro tumor cell inflammation model to explore the regulation of Parkin on the transcription factor NF-?B.LPS treatment resulted in decreased cell viability,significant up-regulation of Bax/Bcl-2 ratio and activation of Caspase-3,which indicating that LPS induces apoptosis through the mitochondrial apoptotic pathway.Treatment of 10 ?M LPS on cells resulted in up-regulation of p-I?B expression,up-regulation of NF-?B transcriptional activity,and high expression of downstream inflammatory factors TNF-?,IL-6,and IL-10,which indicating that LPS treatment can induce NF-?B activation.The expression of Parkin protein was inhibited by small interfering RNA,and the transcriptional activity of NF-?B was detected by the dual luciferase reporter gene assay.and it was found that silencing Parkin protein significantly up-regulated LPS-induced NF-?B transcriptional activity.Overexpression of Parkin significantly inhibited the activation of NF-?B and inhibited the proliferation of tumor cells.At the same time,the inflammatory reaction was induced by LPS on normal tissue-derived HEK 293 cells.LPS caused the NF-?B activation to be impaired.Parkin protein silencing also up-regulated NF-?B activation,but aggravated the decrease of cell viability caused by LPS treatment.To investigate the effect of inflammation on Parkin protein expression,the expression of Parkin protein in HEK 293 cells after LPS treatment was detected and found that to be significantly decreased.Mice were injected intraperitoneally with LPS(100 ?g/mouse)to establish a model of inflammation.The expressions of inflammatory factors TNF-? and NO in the serum of mice were up-regulated at 0.5 h,4 h,and 12 h after LPS injection,and the expression of iNOS was also up-regulated in hippocampus.It was shown that intraperitoneal injection of LPS induced inflammation in the brain of mice,and it was found that LPS-induced inflammatory injury resulted in significant loss of Parkin protein in hippocampus.These results indicate that inflammation causes severe loss of Parkin protein in cells and tissues,while Parkin reduces inflammation by inhibiting the transcriptional activity of NF-?B.