The Effect Of Hsp27 On LPS-induced TLR4 Signaling Pathway And Its Molecular Mechanism

Background and Purpose:Inflammation is the natural response of the immune system to the pathogenic factors outside the organism.Inflammation can be divided into many kinds according to its causes,among which bacterial inflammation caused by biological factors is the most common and widespread in the biological world.The main component of bacterial infection is lipopolysaccharide(LPS),and the TLR4 signaling pathway activated by LPS is the classic way.LPS as a ligand,with the help of LBP and CD 14,it binds to the receptor TLR4 on the cell membrane.LPS binds to TLR4 to form a complex that activates the TLR4 signaling pathway.Subsequently,transcription factors are activated to produce pro-inflammatory mediators.Inflammatory mediators further expand the inflammatory response,in severe cases can lead to systemic inflammation,sepsis and other diseases.Hsp27 molecule is a small heat shock protein with molecular chaperone function.Hsp27 is involved in resisting external damage when the cells are stimulated.It has been reported that heat shock protein(Hsp27)can act as an anti-inflammatory factor to regulate inflammatory response and reduce the mortality of sepsis mice.In this study,we investigated the role of Hsp27 in the regulation of TLR4 signaling pathway induced by LPS.Methods and Results:In this study,we first found that overexpression of Hsp27 could reduce the release of inflammatory factors induced by LPS and down-regulate the TLR4 signaling pathway induced by LPS by transfection of Hsp27 plasmid.The results showed that phosphorylation of Hsp27 was induced by LPS.By adding inhibitor of Hsp27 phosphorylation,it was found that phosphorylated Hsp27 could up-regulate TLR4 signaling pathway induced by LPS.T These results suggest that Hsp27 is involved in the regulation of TLR4 signaling pathway induced by LPS,and this regulation is related to the phosphorylation of Hsp27.And then further explore the specific molecular mechanism of its regulation.By overexpression of Hsp27 in cells,using Western blot,immunoprecipitation and laser confocal technique,it was found that overexpression of Hsp27 promoted the endocytosis and ubiquification degradation of TLR4.By using Hsp27 phosphorylation inhibitor,it was found that only phosphorylated Hsp27 formed complex with TLR4.Conclusion:In summary,under the stimulation of LPS,phosphorylated Hsp27 interacted with TLR4,promoted the endocytosis and ubiquification of TLR4,and down-regulated TLR4 signaling pathway and inflammation.The results of this study provide a further theoretical basis for the negative regulation of inflammation by Hsp27,and also provide a new idea for clinical and drug therapy in the future.