microRNAs may control more than one-third of human genes

More than one-third of human genes could be controlled by minuscule molecules called microRNAs. This claim by US scientists suggests that the molecules, which were first discovered in 2000, could play a role in almost every process from cell birth to cell death, and that they might even be useful in treating human disease.

MicroRNAs are rather like fragments of DNA, and are made up of around 22 chemical 'letters'. They act as controls by effectively blocking a gene from doing its normal job in a cell.

When a gene is switched on, its sequence is converted into messenger RNA, which carries the information to make a protein. MicroRNAs recognize and bind to particular messenger RNAs and stop them from making proteins.

Scientists know that human cells are swimming in microRNAs, but have been unsure how many of our 22,000 or so human genes they control. They might affect only a few hundred genes, say some, or as many as several thousand.

Full news at Nature.com