Induction of overexpression of the 27- and 70-kDa heat shock proteins by bicyclol attenuates concanavalin A-Induced liver injury through suppression of nuclear factor-kappaB in mice

Abstract

Heat shock proteins (HSPs) are molecular chaperones critical for cell survival under adverse environmental conditions and for normal cellular homeostasis. Bicyclol, a novel antihepatitis drug, has been shown to protect against liver injury in animals. However, it is unclear how bicyclol protects against liver injury. We recently found that bicyclol is an inducer of HSPs. We wondered whether bicyclol regulated the expression of HSPs to produce a liver protection in vivo. Thus, this study was designed to address these questions using a mouse model with concanavalin A (ConA)-induced liver injury. Oral administration of bicyclol markedly alleviated ConA-caused liver injury in mice as indicated by the reduction of serum aminotransferases, liver necrosis, and the release of cytochrome c and apoptosis-inducing factor from mitochondria and hepatic DNA fragmentation. Correlated with this, bicyclol induced the increase of mRNA and protein levels of hepatic 27- and 70-kDa HSPs (HSP27 and HSP70) in the mice. Correspondingly, the elevated HSP27 and HSP70 suppressed inhibitor kappaB degradation and nuclear factor kappaB (NF-kappaB) activation that were caused by ConA. The protective effects of bicyclol on ConA-induced mouse liver injury were markedly attenuated by quercetin, an inhibitor of HSPs synthesis. Our results suggest that the antihepatitis drug bicyclol may protect against liver injury by inducing the expression of hepatic HSP27 and HSP70 and consequently inhibit the transcription factor NF-kappaB-mediated apoptosis and necrosis in liver tissue.