Only about 10 percent of human genes, for example, are actively producing proteins in a given cell at a given time. The remaining 90 percent are silenced by a various mechanisms that act to interfere with gene transcription into messenger RNA or translation of messenger RNA into protein.
In a new study published online May 16 in the journal Nature, a team of scientists at The Wistar Institute and the University of California, San Diego, report identification of an important new gene-silencing mechanism, one that blocks the cellular machinery responsible for translating messenger RNA into proteins at specific genes.
The findings suggests that small bits of RNA known as microRNAs, known to help regulate genes but not used for protein production, may be operating in a completely novel way to prevent genes from producing proteins. MicroRNAs have been implicated in a number of cancers, and the newly outlined gene-silencing mechanism offers promising potential targets for anti-cancer interventions.
"Some microRNAs closely match their sequences against particular messenger RNA sequences to target them for destruction," explains Ramin Shiekhattar, Ph.D., a professor"in the Gene Expression and Regulation Program and the Molecular and Cellular Oncogenesis Program at Wistar and senior author on the new study. "That’s one way we know that microRNAs can silence genes. That mechanism requires extraordinary specificity, however, and we suspected that microRNAs were also acting in some other way to inhibit gene translation into protein. By tracking the associations between molecules involved in generating microRNAs and other molecules in the cell, we uncovered an entirely new pathway
Source:The Wistar Institute