Heat Shock Protein 60 On The Surface Of Apoptotic Cells And E. Coli Expression And Significance Of Research

Damage-associated molecular patterns (DAMPs) are signals released from dying cells evoking the immune system response in several inflammatory disorders. In normal situations, many of DAMPs are nuclear or cytosolic proteins with defined intracellular function, but they could be found on the cell surface following tissue injury. The biological function of the translocated DAMPs is still not well known and an efficient delivery of these molecules on the cell surface is required to clarify their biological effects. In this study, we demonstrated that an unclassical secretory signal peptide, N-terminal18amino acids of HASPB (HASPB-N18), could efficiently deliver HSP60, HSP70, and HMGB1on the cell surface. Furthermore, the delivery of these molecules on the cell surface by HASPB-N18is not limited to a special cell line because several cell lines could use this delivery signal to deliver these molecules on the cell surface. Moreover, we demonstrated that HSP60on the cell surface delivered by HASPB-N18could be recognized by a soluble form of LOX-1, which implies that DAMPs on the cell surface delivered by HASPB-N18have a proper conformation during transport. Therefore, delivery of DAMPs by HASPB-N18is a reliable model to further understand the biological significance of DAMPs on the cell surface. Heat shock proteins (HSPs) were originally identified as stress-responsive proteins and serve as molecular chaperones in different intracellular compartments. Translocation of HSPs to the cell surface and release of HSPs into the extracellular space have been observed during the apoptotic process and in response to a variety of cellular stress. Here, we report that UV and cisplatin treatment rapidly induced the expression of membrane-bound HSP60, HSP70, and HSP90upstream the PtdSer exposure. Membrane-bound HSP60, HSP70and HSP90could promote the release of IL-6and IL-1β as well as DC maturation by the detection of CD80and CD86. On the other hand, latex beads coated by HSP60, HSP70, or HSP90could be uptaken by bone marrow-derived dendritic cells (BMDCs) and HSP60, HSP70and HSP90on dying cells could facilitate the clearance of apoptotic cells. LOX-1as a common receptor for HSP60, HSP70, and HSP90is response for their recognition and takes up apoptotic cells. Furthermore, membrane-bound HSP60, HSP70and HSP90could facilitate the cross-presentation of OVA antigen from apoptotic E.G7cells and inhibition of the uptake of apoptotic cells by LOX-1decreases the cross-presentation of cellular antigen. Taken together, these results demonstrate that membrane-bound HSP60, HSP70and HSP90have a dual property in the interaction of apoptotic cells with BMDCs. Escherichia coli (E. coli) is an emergering pathogen that cause peritonitis. Macrophage cells are professional phagocytic cells that play an essential role in host defense against invading pathogens; however, the precise mechanism is not well known. Proteins exposed on pathogen surface mediate attachment to mammalian extracellular components, thus favoring the attachment and invasion of host cells, and participate in mounting the host inflammatory response. Identification of attachment factors and clarify the mechanisms are key steps to develop novel therapeutic approaches. Heat shock proteins of the HSP60family are a highly conserved group of proteins essential to all living organisms. Their key role consists of mediating protein folding within the cell to guarantee normal function. The HSP60in E. coli is called GroEL. In this study, we found that during the invading process, the bacteria surface-associated GroEL of E. coli is significantly up-regulated. We established a strain of E. coli over expressing GroEL on the bacteria surface, and using this we found that surface-associated GroEL played essential role in pathogen invasion and made mice more susceptible to E. coli peritonitis. We also found that GroEL could be recognized by LOX-1and thus cause the phagocytic of pathogen by macrophage. In addition, GroEL could increase the expression of LOX-1on macrophage which supports adhesion of gram-negative bacteria. These findings add to the growing field of research that implicates molecular chaperons as having extracellular functions, including bacterial adherence to host cells. Thus, LOX-1may support the adhesion of E. coli by acting as a Pattern Recognition Receptor (PRR) for bacterial GroEL. Our results suggest that GroEL as a novel therapeutic target in modulating the immune response in infectious and inflammatory conditions.