Visually impaired mice are shedding light on how cataracts are formed. Research in Nature (Vol. 424, No. 6952, dated 28 August 2003, pp. 1071-1074) highlights the importance of a DNA-degrading enzyme that helps developing lenses to remain clear.
The lens is made up of clear fibre cells. As they form, internal structures, such as the nucleus and power-boosting mitochondria, are broken down to prevent the lens from clouding up. Shigekazu Nagata and colleagues have discovered an enzyme, known as DLAD, that catalyses this degradation. The protein is found in normal mouse lens cells, they report. Mice lacking the enzyme are unable to degrade fibre cell DNA, and they develop cataracts.
DLAD is also found in human lens cells, so some cataract patients may carry a deficiency in the DLAD gene, the team speculates. The researchers also hope that the visually impaired mice will provide a useful animal model with which to study human cataract development.
Osaka University Medical School, Japan
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