DNase activity in murine lenses: implications for cataractogenesis.

In murine lens extracts a Mg(2+)-dependent DNase activity was found and characterized with respect to its ionic conditions. The lenticular DNase can be clearly distinguished from DNaseII. Only a moderate DNase activity is detectable in intact nuclei of lens cells from 1-day-old mice, but DNase is obviously present with high activity in lens cell nuclei from 7-day-old mice. During this time, when murine eyes are not yet open, and the fiber cell nuclei including the nuclear membrane remain to be completely digested, only weak activity can be detected in cytosolic lens extracts. In three allelic dominant mice mutants exhibiting hereditary cataracts the DNase activity is inhibited. The decrease of DNase activity follows the same directionality (Cat-2ns > Cat-2no > Cat-2t) as the decrease in the relative content of water soluble lens proteins, which might be used as a rough indicator for the severity of cataractogenesis. Both trends are highly significant (P < 0.0001).