MicroRNAs are known to affect the levels of both messenger RNA (mRNA) and protein. But as protein production is dependent on the presence of mRNA, it was not clear what the relative contributions of microRNA-mediated mRNA cleavage and translational repression were. These authors have parsed out the two mechanisms, and unexpectedly find that microRNAs function primarily by affecting mRNA levels rather than their translation. This suggests a reassessment of many previous conclusions is necessary.
- Huili Guo
- Nicholas T. Ingolia
- David P. Bartel
