Deadly Diced DNA

Science Signaling  20 Apr 2010:
Vol. 3, Issue 118, pp. ec117
DOI: 10.1126/scisignal.3118ec117

Mammalian cells undergoing programmed cell death, or apoptosis, destroy DNA with the deoxyribonuclease known as DFF40. Cells of the worm Caenorhabditis elegans also undergo cell death, but they do so without a DFF40 enzyme. Nakagawa et al. (see the Perspective by Liu and Paroo) searched for other nucleases that might be involved in worm apoptosis by systematically depleting nucleases with interfering RNA. They found that the ribonuclease Dicer, known for its role in sequence-specific silencing of gene expression, was cleaved by a protease that changed Dicer’s catalytic activity. The remaining C-terminal fragment switched from being a ribonuclease to a deoxyribonuclease. Thus, caspase activation leads to DNA degradation in the worm as well.

A. Nakagawa, Y. Shi, E. Kage-Nakadai, S. Mitani, D. Xue, Caspase-dependent conversion of Dicer ribonuclease into a death-promoting deoxyribonuclease. Science 328, 327–334 (2010). [Abstract] [Full Text]

Q. Liu, Z. Paroo, Dicer’s cut and switch. Science 328, 314–315 (2010). [Summary] [Full Text]