A Dynamic Trio of Findings

Blurring, chopping and blocking. Three online items this week all deal with some pretty dynamic phenomena.

The blurring is in our perceptions. It turns out that if you even think you have lost money in an experiment, your ability to distinguish between musical notes will be hampered. What’s the connection? Dr. Rony Paz has been showing that this tendency to lump sounds together is tied to fear. In our evolutionary past, humans may have survived because anything that sounded remotely like a predator aroused an immediate “fight or flight” response. But if mild stress can provoke a similar reaction, we might be looking at factors in anxiety disorders and PSTD. One clue as to why some people may be more susceptible to these problems than others can be found in the fMRI scans that the experiment’s subjects underwent: All showed activity in the amygdala – the brain’s emotion center – but they had different levels of activity in a second brain area that modulates the amygdala’s response. Those that had higher activity in the second region were less likely to have trouble distinguishing between notes.

The chopping takes place in our cells, on strands of RNA. This is done by cellular machinery that cleaves longer strands of precursor microRNA into the short bits of non-coding microRNA that perform all sorts of regulatory duties in the cell. In turns out, however, this machinery can sometimes accidentally chop though look-alike target sites on messenger RNA – the strands that code for proteins. Dr. Eran Hornstein and Prof. Naama Barkai call this problem “efficiency vs. specificity” – how to keep the machinery up to the task of cleaving all the microRNA that’s needed, but not so good at its job that it cuts up all the RNA in sight. Their findings: The machinery is self-regulating. It senses levels of precursor microRNA and then ramps down or tools up its own production.

The blocking occurs right at the entrance to the cell nucleus. Over years of research, Prof. Rony Seger has traced the chain of protein activity that passes growth signals – including those involved in cancer growth – from the outer cell membrane to the DNA in the nucleus. Several years ago, he discovered a sort of “passport” on those protein signals that gets “stamped” with a phosphorous complex, allowing them to pass through the nuclear membrane. He and his team then created peptides – protein bits that imitate the passport segment – and tried them out in mouse models of various cancers. The idea is that these peptides would intercept the phosphorous stamps, leaving the signaling proteins outside the nucleus. And that, apparently, is what happened, especially in the mouse models of melanoma, in which the tumors completely disappeared.