[
Science,
1994]
Like people, cells die in different ways: accident, murder, old age, even suicide. In fact, cellular suicide isn't just a curiosity, it's necessary for the health of the organism. During embryonic development, for example, it helps weed out superfluous nerve cells, as well as immune cells that might attack and damage the body's own tissues. Like a spy-plane pilot who carries a little vial of poison under his seat in case he's captured, cells carry in their nuclei a genetic program for suicide that can be set in motion, should the cell receive orders to self-destruct. Now, after years of eluding researchers, the genes that carry out the suicide program are coming into the light...
[
Nature,
1994]
RNA trespasses in what was once thought to be protein's province. The notion that RNAs can be enzymes, binding specifically to ligands, cofactors and substrates, is now commonplace; yet only a few years ago, these were the sacred acts of proteins. History may be about to repeat itself. Regulatory proteins bind to specific sequences in the genes or messenger RNAs they control, and so determine how much a gene is expressed, in what cells, and when. But why should these regulators have to be protein? Why not RNA? We already know, in bacteria, of RNAs that can control gene expression through remarkably sophisticated mechanisms. Now, two reports in Cell not only identify a tiny, repressing RNA in animal cells, but also show that it acts upon a region of mRNA often thought to be barren and insignificant. Although this could be a rare, deviant case, there is the tantalizing possibility that a new family of regulatory RNAs awaits discovery.