Role of Glutathione S-Transferases in Lens under Oxidative Stress

Abstract

The polymorphic expression of glutathione S-transferase (GST) in animal lenses has been demonstrated by purification with affinity chromatography, immunochemical analysis with Western-blotting and amino acid sequencing of the N-terminal regions. Three major classes of GST (class α, γ or π) have been identified in human, bovine, pig, rabbit, rat and guinea pig. They show a typical GSH-conjugation reaction with various chemicals, including organic peroxides. These GSTs possess unique properties against oxidative stress, that is, α-class GST exhibits a GSH-peroxidase-like activity, μ-class GST shows a potent resistance to naphthoquinone and H₂O₂, and π-class GST shows a high sensitivity to a variety of oxidants. Because the oxidative stress is believed to be a major factor in the development of cataracts, these unique expression patterns of GST in animal lenses reveal an important factor in the formation and development of oxidant-induced cataracts, including naphthalene cataract and senile cataract. The most typical example has been presented that effect of curucumin on the prevention of cataract through the induction of GST. This review summarizes the evidence for the involvement of GST in cataractogenesis, which may be seen to support it as an important risk.