original version of this story appeared in Quanta Magazine.
The world is a dangerous place for RNA molecules. Unlike DNA, which can survive for millions of years in a surprisingly stable double-stranded form, RNA is not built to survive even within the cell that created it. RNA can be degraded in minutes unless it is protectively linked to a larger molecule below. And outside the cell? Forget it. Voracious RNA-destroying enzymes are ubiquitous and secreted by all forms of life as a defense against viruses that write their genetic identity in RNA code.
There is one way for RNA to survive intact outside the cell. It’s inside a small protective bubble. For decades, researchers have noticed that cells release cell membrane bubbles called extracellular vesicles (EVs) filled with degraded RNA, proteins, and other molecules. However, these bags were thought to be little more than garbage bags that pulled decomposed molecular junk out of cells during routine clean-up.
Then, in the early 2000s, Hadi VaradiMolecular biologists at the University of Gothenburg revealed that the RNA inside some EVs did not look like garbage. The cocktail of RNA sequences is quite different from that found inside cells, and these sequences works flawlessly. When Valadi’s team exposed human cells to EVs from mouse cells, they saw how the human cells took up the RNA message, “read” it, and produced functional proteins that they could not otherwise make. I was shocked when I observed it.
Valadi concluded that cells specifically package RNA strands into vesicles to communicate with each other. “If you’re outside and you see it’s raining, you can say, ‘If you’re going to go out, please bring an umbrella,'” he said. In a similar way, he suggested, cells could warn neighboring cells about exposure to pathogens or harmful chemicals before they encounter danger.
Since then, improvements in sequencing technology that have allowed scientists to detect and decipher smaller and smaller RNA segments have uncovered a wealth of evidence supporting this theory. Since Valadi published his experiments, other researchers have also observed EVs filled with complex RNA combinations. These RNA sequences contain detailed information about the cell that created them and can cause specific effects in recipient cells. This discovery has led some researchers to suggest that RNA may be a molecular lingua franca that transcends traditional taxonomic boundaries, and thus can encode messages that are understandable across the tree of life. .
In 2024, new research reveals further layers to this story, including bacteria and eukaryotic cells. Also exchange archaea This confirms that this phenomenon is universal in all three realms of life. Another study showed that plants and infected bacteria are capable of this, expanding our understanding of cell communication across kingdoms. Use packets of RNA to wreak havoc As a form of co-evolutionary information warfare: enemy cells read RNA and build proteins that self-harm with their own molecular machinery.
“I’ve been in awe of what RNA can do,” he said. amy backis an RNA biologist at the University of Edinburgh, but was not involved in the new research. For her, understanding RNA as a means of communication “goes beyond understanding the sophistication and dynamic nature of RNA within cells.” Sending information across cells may be one of the primary roles of cells.
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microbiologist Suzanne Erdmann study viral infections haloferax volcanoa single-celled organism that thrives in incredibly salty environments such as the Dead Sea and the Great Salt Lake. Although unicellular bacteria are known to widely exchange EVs, H. volcanii It’s not a bacteria. Paleozoica member of the third evolutionary branch of life, characterized by cells that are constructed differently than bacteria and eukaryotes like us.
EVs are the same size and density as the virus particles that Erdmann’s team studies at the Max Planck Institute for Marine Microbiology in Germany, so “they always appear when you isolate and purify the virus,” she says. Eventually, her group became curious and decided to take a peek to see what was inside.
