Human cells can write foreign RNA into genetic DNA code

Human cells can write foreign RNA into genetic DNA code

Polymerase theta, present in human cells, has been found capable of copying foreign messenger-RNA in your cells and incorporating it into your personal DNA; it is highly expressed in cancer cells and drug resistance.

Your DNA is your genetic code in all your cells; your personal blueprint. In order to influence your life, it sends out messengers - exact copies of your DNA - which, in turn, can make proteins in your body giving you brown eyes or black hair. Human cells use enzymes called 'polymerases' to build these messenger molecules - messenger RNA. 

It has long been believed that  polymerases worked only in one direction, copying DNA into RNA, avoiding any possibility of rogue RNA being copied and finding its way into your DNA blueprint.

This system would prevent RNA from viruses or parasites or gut bacteria ‘accidentally’ being incorporated into your DNA blueprint.

Unfortunately, this is no longer known to be true. it is now well established that HIV, for example, can have its RNA copied in the human body and the RNA can be incorporated into your DNA structure. This is because HIV uses its own ‘reverse polymerase’.

Thomas Jefferson University researchers decided to look at human polymerases to see if any could act in this ‘reverse’ way and found that one, Polymerase theta, did just that.  "This work opens the door to many other studies that will help us understand the significance of having a mechanism for converting RNA messages into DNA in our own cells," says Richard Pomerantz, PhD, associate professor of biochemistry and molecular biology at Thomas Jefferson University. "The reality that a human polymerase can do this with high efficiency, raises many questions.”

It is conceivable that this system is some sort of ‘Failsafe’ mechanism, allowing copies of your own RNA to be made and then incorporated back in to repair problems that have arisen in your DNA. But what is to stop RNA from an external source being incorporated too?

There are 14 different polymerases in human cells, with three performing the great majority of the copying work. Pomerantz's team instead started by investigating an unusual polymerase; Polymerase theta.  It is know to be one of the repair polymerases involved when there's a break or error in the DNA strands, acting as a reverse transcriptase and making DNA from RNA. However, it is already known that Pol theta appears rather error-prone and can even cause mutations.  

The researchers studied Pol theta and showed that it was capable of converting and incorporating RNA copies into your DNA and was as effective as the HIV reverse polymerase in doing this.

In fact, Polymerase theta was more efficient and introduced fewer errors when copying an RNA template to write new DNA messages, than when copying DNA into DNA, suggesting that this RNA-copying function could be its primary purpose in the cell.

The researchers also found Pol theta was uniquely able to change shape in order to accommodate the larger RNA molecules.

"Our research suggests that polymerase theta's main function is to act as a reverse transcriptase," says Dr. Pomerantz. "In healthy cells, the purpose of this molecule may be toward RNA-mediated DNA repair. In unhealthy cells, such as cancer cells, polymerase theta is highly expressed and promotes cancer cell growth and drug resistance." 

“And how would it deal with messenger-RNA for a spike protein, following a Covid vaccination, one wonders? Could some version of that end up incorporated into your previously healthy DNA?” asked Chris Woollams, former Oxford University Biochemist and a founder of CANCERactive. "Surely, that must be one of the 'serious questions' raised?"


Go to: How the Virome affects your Health



  1. Gurushankar Chandramouly, Jiemin Zhao, Shane McDevitt, Timur Rusanov, Trung Hoang, Nikita Borisonnik, Taylor Treddinick, Felicia Wednesday Lopezcolorado, Tatiana Kent, Labiba A. Siddique, Joseph Mallon, Jacklyn Huhn, Zainab Shoda, Ekaterina Kashkina, Alessandra Brambati, Jeremy M. Stark, Xiaojiang S. Chen, Richard T. Pomerantz. Polθ reverse transcribes RNA and promotes RNA-templated DNA repair. Science Advances, 2021; 7 (24): eabf1771 DOI: 10.1126/sciadv.abf1771

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