A New Discovery Challenges Our Understanding of Genetics

Like viruses, our cells can convert RNA back into DNA

During my introductory biology courses, our exams were all multiple choice. If there’s anything I learned bubbling in scantron sheets, it’s that there is always an exception. We are constantly redefining our understanding of biology, even down to the basics.

Early on, we learn about the Central Dogma in biology. It describes how the cells in our body use genetic information. Our genome is like a master cookbook of recipes. We want to keep the book in tip-top condition so we copy out the sections we need to use. This forms a product called messenger RNA.

This is the first step in the central dogma, transcription. We are writing down a message with a gene or recipe that we want to use. Then we export it to the cell’s kitchen, the ribosomes, where it translates into protein. That’s the Central Dogma in a nutshell.

We can’t turn our proteins back into messenger RNA. Until recently, we thought only viruses could convert messenger RNA into DNA. Now scientists report the first evidence that human cells can also perform this feat. Their findings were published in Science Advances on June 11th, 2021.

Breaking the Central Dogma

There’s a lot of different proteins in our cells that help us create messenger RNA. Some of them are highly specialized while others remain a little mysterious. In this study, scientists decided to look at Polymerase θ (Polθ).

Polθ can unravel DNA, allowing it to make a copy of a gene. But it makes a lot of errors along the way. Nonetheless, it also can repair specific types of breaks in the DNA. Interestingly, it’s often expressed in cancer cells, especially those resistant to therapy.

Polθ also has a bit in common with the machinery viruses use to write their RNA into a host genome. The researchers were curious, whether Polθ would do the same. They tested the isolated Polθ protein against the HIV viral polymerase. It turned RNA into DNA more efficiently than HIV polymerase.

Takeaways

Does this mean that foreign RNA (such as in a vaccine) can be transcribed back into the DNA?

Probably not, remember that this polymerase isn’t expressed in most cells and organs in our body. Our muscles don’t produce any of this protein, and that’s the site of mRNA vaccines. Rest assured, you’re still more than safe!

To conclude

In biology, nothing is ever simple. It looks like the central dogma of biology might not be so universal after all. This research could help us learn why cancer cells express this protein. Additionally, this discovery could have implications for future gene therapies. I’m excited to see the research develop around this finding.