Investigation And Identification Of Novel Heat Shock Protein Hsp70L1 Receptors On Human Dendritic Cells

Hsp70L1 has heat inducible characteristics and typical motifs of HSP70 subfamily. Hsp70L1 can bind to dendritic cells (DC) specially, and induce DC activiation, which acts as a new potent adjuvant for peptide immunization, so identification and investigation of Hsp70L1 receptors on DC is essential for studying Hsp70L1 and DC interaction. Two methods were applied in testifying Hsp70L1 receptors on DC in this study: GST pull-down of Hsp70L1 combined with immature DC membrane proteins and receptor binding assay of Hsp70L1 with HSP70 related receptor modified HEK293 cells. The results of GST pull-down indicated Hsp70L1 could combine with TLR4,TLR2 and Lox-1 in vitro, and the receptor bindind assay showed FITC labeling Hsp70L1 could bind to CD40 or TLR4 stable expressing HEK293 cells in contrast with HEK293. The study of the biological function of the interaction of Hsp70L1 and TLR4 is attractive and important for make out the adjuvant effect of Hsp70L1. The results showed that compare with wild type mouse group, HSP70L1 promote the DC mature phenotypic changes and proimflammatory cytokines TNF-αand IL-1βproducing and induce CEA specific cellular immune response are less efficient in TLR4 dificient mouse. Human DC stimulated by CEA-Hsp70L1 induce specific cellular immune responses could also be suppressed by human TLR4 inhibitor The interaction of Hsp70L1 and TLR4 lead to activation of intracellular NF-κB and MAPK cascade signaling pathway It suggested TLR-4 was one of critical receptor of HSP70L1 on DCs. These results may help us to explore the novel mechanism of the adjuvant effect of Hsp70L1.