WIKIMEDIA COMMONS, VOSSMANSome circular RNA molecules serve as molecular “sponges,” binding to and deactivating gene modulators called microRNAs to influence gene expression, according to two papers published this week (February 27) in Nature. The findings reveal a hidden world of previously unexplored RNA molecules, and act as a reminder that there is more to RNA than simply being a messenger between DNA and the proteins it encodes.

Over the past 20 years, scientists have discovered a series of unexpected forms of RNA, from the unusually short and long to those that blocked other RNA strands from being translated into proteins. But because typical RNA sequencing approaches work by detecting molecules with tails, circular RNAs, whose ends are joined together, went unnoticed. Now, however, new sequencing methods are revealing the existence and function of circular RNA in nematodes, mice, and humans.

“It’s yet another terrific example of an important...