Host: The Japan Radiation Research Society
Co-host: Asian Association for Radiation Research
Heat shock proteins (HSPs) are induced by various physical, chemical and biological stresses. HSPs are known to function as molecular chaperones and they not only regulate various processes of protein biogenesis but also function as lifeguards against proteotoxic stresses. Since it is very useful to discover nontoxic chaperone-inducing compounds, we searched for them in herbal medicines. Some herbal medicines had positive effects on the induction of HSPs (Hsp70, Hsp40, Hsp27) in cultured mammalian cells. We next examined two major constituents of these herbal medicines, glycyrrhizin and paeoniflorin. Glycyrrhizin had an enhancing effect on the HSP induction by heat shock but could not induce HSPs by itself. In contrast, paeoniflorin had not only an enhancing effect but also an inducing effect by itself on HSPs expression. Thus, paeoniflorin might be termed a chaperone inducer and glycyrrhizin a chaperone co-inducer. Treatment of cells with paeoniflorin resulted in enhanced phosphorylation and acquisition of DNA binding ability of heat shock factor 1 (HSF1), as well as the formation of characteristic HSF1 granules in the nucleus, suggesting that the induction of HSPs by paeoniflorin is mediated by the activation of HSF1. Also, thermotolerance was induced by the treatment with paeoniflorin. In our preliminary study, paeoniflorin could prevent HCl-induced stomach ulcers, extend life span of nematoda, and suppress the growth of tumor cells.
