Abstract
Rat glutathione S-transferase (GST) subunit 3 gene has polymorphism, one type encoding Asn(198)-Cys(199) (NC type) and another encoding Lys(198)-Ser(199) (KS type). To examine whether the two types of GST 3-3 exhibit different susceptibilities to oxidative stress in vivo, rats were administered with CCl(4), a hepatotoxin causing severe oxidative stress, and its effect on liver GST 3-3 was compared. Decrease in GST activities in liver due to CCl(4) administration was more evident in NC type rats than in KS type rats, and most GST activities of KS type rats were confined to S-hexylglutathione-Sepharose, whereas those of NC type rats were not. Decreases in GST subunits 1 and 3 were more marked in NC type rats and glutathiolated NC type GST 3-3 was also detected. These results indicated that KS and NC type GST 3-3 of rat livers exhibited different susceptibilities to CCl(4) in vivo. A protein consisting of a subunit with molecular mass of 90 kDa was shown to bind to KS type GST 3-3 but not to NC type. This protein was identified as heat-shock protein (HSP) 90beta by N-terminal amino acid sequencing and immunoblotting. A specific HSP90 inhibitor geldanamycin released their binding. There was no difference in the binding of apoptosis signal-regulating kinase 1 to GST 3-3 between NC and KS type rats. These findings suggest that HSP90 interacts with KS type GST 3-3 and thereby protects it from inactivation due to CCl(4).