| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2002: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2001: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
This study has the focus on the effect of stress signals on the function of innate immune system. Recently, heat shock proteins are known to function as a danger signal as well as molecular chaperone. Here, we mainly examined the relationship between the structure and the immune functions of heat shook protein (Hsp) 70 family, and also elucidated molecular mechanisms in innate immunity for recognizing a signal of Hsp70.
We, first, studied the molecular interaction between BiP, an ER-resident Hsp70, and a heat-denatured ovalbumin, a non-inhibitory serpin molecule. BiP did not interact with the native molecule, but significantly recognized some hydrophobic peptides which were exposed only upon heat-denaturation of hen ovalbumin. Quantitative analysis showed that the equilibrium constant K_d for this interaction was estimated to be approximately 0.5μM. secondary, structural requirement of murine inducible Hsp72 for recognition by innate immune cells was examined. When the recombinant Hsp72 and its C-terminal deletion proteins were produced, the region of α-helices at the C-terminal portion was found to be responsible for formation of oligomers of Hsp72. We found that Hop72 was recognized by the innate immune cells such as macrophages, dendritic cells, and NK cells as well as B cells of an antigen-presenting cell. Finally, we tried to characterize the receptor molecule on P388D1 cell line that con bind Hsp72. Protease treatment of P388D1 cells with proteinase K or trypsin significantly abolished the binding of Hsp72, suggesting the proteinaceous molecule as a surface receptor. The fact that the molecules that inhibit the binding of Hsp72 to P388D1 cells are the members of ligands for scavenger receptors (SR) suggests that a candidate receptor for Hsp72 on P388D1 cells may be one of the SR identified so far or other proteinaceous molecule with similar binding properties to that of SR.
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