Effect of streptozocin-induced diabetes mellitus on expression of methionine sulfoxide reductases and accumulation of their substrates in mouse lenses

To determine the influences of early-stage diabetes mellitus on methionine sulfoxide reductases (Msrs) expression in lenses, streptozocin (STZ)-induced diabetic mice as animal models were used in this study. The results showed that the contents of methionine sulfoxide (MetO), protein carbonyl (PC) and Malondialdehyde (MDA) in the lenses of STZ-induced diabetic mice after 14 days were significantly higher than that in the normal control, level of total sulfhydryl groups (TSH) was 60% of normal control, and mRNA expressing levels of the MsrA and MsrBs were significantly decreased compared with normal group, as was the expression of MsrB1 protein. These results suggest that STZ not only causes increased oxidative stress, but also suppresses Msr mRNA and MsrB1 protein expression during early-stage diabetes in mice. However, the mechanism remains to research.

► The contents of methionine sulfoxide, protein carbonyl and malondialdehyde in the STZ-induced diabetic mouse lenses were significantly higher than that in the normal control. ► The levels of total sulfhydryl groups, the MsrA and MsrBs mRNA expression were significantly decreased compared with normal group, as was the expression of MsrB1 protein. ► The STZ-induced diabetic mice result in not only increasing oxidative stress but also suppressing Msrs mRNA and MsrB1 protein expression in the lens.