Molecular 'Superman' Rescues DNA from Catastrophic Collisions

Scientists have recently identified a molecular "Superman" of sorts, which rescues DNA from catastrophic collisions that can lead to various diseases, including cancer.

Countless times we've witnessed Superman in all his glory, flying at lightning fast speeds and using his godly strength to save the day, but researchers with Cold Spring Harbor Laboratory (CSHL) have shown that this heroism is demonstrated every day within our own bodies.

Every time a cell divides, our DNA must be replicated, which isn't a problem except when considering the fact that other molecular machines are battling to get a piece of the genome, too. This includes the process known as transcription, during which the letters of our DNA are being copied to form a template that will guide the formation of proteins. However, the genome may not be big enough for both copying machines, meaning they can't occupy the same bit of genetic track at once. Otherwise, they will inevitably collide.

That's when this molecular Superman, now identified as the form of a protein known as Dicer, comes into play. Dicer, while better known for its role in selectively silencing genes via a process called RNA interference (RNAi), helps free transcription machinery from DNA so that replication can occur.

"When Dicer is mutated, replication stalls and DNA in the region becomes damaged," lead researcher Robert Martienssen, a CSHL professor, explained in a statement. "This was a new role for a protein that we thought functioned solely in RNAi."

But in the new study, published in the journal Cell, Martienssen and his colleagues found that Dicer functions more broadly across the entire genome, not just during RNAi. In fact, it controls the release at hundreds of extremely active genes.

"These are genes that are in constant use by the cell - we call many of them 'housekeeping' genes because they are required for basic survival," said lead author Stephane Castel.

Without Dicer, transcription machinery would for sure head for a catastrophic collision with replication. These accidents, in turn, would cause massive segments of DNA to be lost with each cell division, leading to changes associated with aging and diseases like cancer.

So, as always, Superman was there to save the day.