DIFFERENTIAL DISPLAY DETECTS ALTERED GENE-EXPRESSION BETWEEN CATARACTOUS AND NORMAL HUMAN LENSES

PURPOSE. TO identify and analyze differentially genes expressed betwee n lens epithelia dissected from age-related cataractous and noncatarac tous human lenses. METHODS. RNAs from 50 pooled cataractous and 25 poo led noncataractous epithelia were compared by reverse transcription-po lymerase chain reaction differential display (RT-PCR-DD). Two differen tially displayed bands were chosen for further study. These were reamp lified, cloned, and sequenced. Expression of these genes was further e valuated in pooled and individual epithelia by RT-PCR with gene-specif ic primers. RESULTS. Significant differences in gene expression were d etected between the cataractous and the noncataractous epithelia. Thre e mRNAs displayed higher levels and 12 mRNAs displayed lower levels of expression in the cataractous samples compared with that in the nonca taractous samples. Of the mRNAs expressed at higher levels, one was id entified as metallothionein IIa (METII). Of the mRNAs with decreased e xpression, one was identified as protein phosphatase 2A regulatory sub unit (P2A-RS). Overexpression of METII and underexpression of P2A-RS w ere confirmed in pooled and individual epithelia. CONCLUSIONS. These r esults provide evidence that age-related cataract is associated with a lterations in the expression of multiple epithelial genes including ME TII and P2A-RS. METII is a detoxification protein induced by oxidative stress, and P2A-RS is a mitotic suppressor involved in cell-cycle con trol. These results implicate these proteins and their associated func tions in the maintenance of lens transparency.