Working with C. elegans, a team led by researchers at the University of Colorado at Boulder have now shown that the Dicer ribonuclease (DCR-1), instead of being inactivated by caspases, undergoes a change of function. DCR-1 normally processes small RNAs but cleavage by the CED-3 caspase produces a C-terminal fragment which shows deoxyribonuclease activity and produces 3′ hydroxyl DNA breaks on chromosomes and promotes apoptosis. Although there are many enzymes that cleave either RNA or DNA, this is the first demonstration that proteolysis of a ribonuclease can generate a deoxyribonuclease.
The researchers are now investigating whether the function of DCR-1 can be altered in the same way in human cells – if so, the authors hope that their work may lead to new ways to treat diseases caused by abnormal apoptosis such as cancer and autoimmune diseases.
The study is published in the journal Science.