MicroRNAs won Victor Ambros and Gary Ruvkun the 2024 Nobel Prize in Medicine. Thomas Cech (Nobel Laureate for the discovery of catalytic RNA) has found a fun way to explain how they work. His book, which I reviewed a few weeks ago, is a mine of insights and information. Here is a small excerpt.

“Instead of inhibiting gene activity, let’s think of inhibiting traffic flow across the East River in New York City. Multiple bridges, including the famous Brooklyn Bridge, carry traffic into and out of Manhattan; these are analogous to the multiple genes whose activity needs to be reduced before an embryonic cell can become a brain cell. The traffic across each bridge can be inhibited by events occurring in Manhattan – road repairs, traffic accidents, or a sudden snowstorm. These events are akin to the actions of microRNAs on gene activity. Each bridge will be affected by these events to a different extent, depending on its location and other factors. The effects will be additive; combining a stalled truck and a sudden snowstorm will really shut things down. Similarly, with RNA interference, it’s the combination of the number of microRNA binding sites – and the prevalence of those particular microRNAS – that tunes down the translation of an mRNA into protein.”