This brain gene can move through human DNA — and scientists found it inside a virus

Scientists have identified a human gene with an unusual double life: it appears to perform a biological function in brain cells while retaining the ability to move around the genome.

The gene, known as BC200, has an evolutionary history that makes the discovery particularly unusual. It originated millions of years ago from a piece of mobile DNA called a transposon, or “jumping gene”. Most transposon-derived sequences that became part of useful genes eventually lost their ability to move.

BC200 appears to be different.


Researchers at Cornell University found evidence that the gene remains mobile and can insert itself into new locations in a genome. Their study, published in Science on September 24, also found BC200 inside molluscum contagiosum virus, a human poxvirus that infects skin cells.

The finding raises a series of questions about how human genes evolve, how fragments of mobile DNA acquire useful functions and whether some of these genetic elements can continue moving between genomes long after they first became part of the human lineage.

The researchers are now investigating whether BC200's mobility has consequences for human health, including its possible links to cancer and neurological disease.

BC200 began as a piece of DNA that could move

Long before BC200 became associated with human neurons, its evolutionary ancestor was a transposon.

Transposons are stretches of DNA that can change their position within a genome. Some can effectively copy themselves and insert the new copy elsewhere, while others move directly from one location to another.

Because of this behaviour, they are often called jumping genes.

Their activity can sometimes cause problems. If a mobile element inserts itself into an important gene or regulatory region, it can interfere with normal cellular processes. But transposons are not simply genomic troublemakers.

Over millions of years, organisms have also repurposed pieces of transposon DNA for useful biological functions. Some have become parts of genes or regulatory sequences involved in development, immunity and other cellular processes.

The usual pattern is that once a transposon-derived sequence is recruited for an important function, it loses the machinery that allowed it to move.

That is what makes BC200 unusual.

According to Cornell researchers, the element appears to have been converted into a functional human gene while retaining its mobility.

“Genes that come from transposable elements and that are repurposed for cellular functions are typically no longer transposable,” Cornell geneticist Cedric Feschotte, a senior author of the research, said in describing the finding.

BC200 appears to have escaped that evolutionary trade-off.

A brain gene with a role that is still being investigated

BC200 is not a newly discovered stretch of human DNA.

Scientists first identified it in the late 1980s as an abundant non-coding RNA in human neurons. Unlike messenger RNAs that provide instructions for making proteins, non-coding RNAs can perform other regulatory roles inside cells.

BC200 is particularly associated with the nervous system. Researchers have evidence that it may influence how messenger RNAs are translated into proteins within neurons.

That could make it relevant to the way brain cells maintain and regulate their activity.

But scientists do not yet have a complete picture of what BC200 does in healthy human cells. Its precise physiological role remains an active area of research.

The new discovery adds another layer to the story.

Researchers now have evidence that the same genetic element associated with neurons also retains characteristics of its transposon ancestry.

BC200 is found at low levels in germ cells, including sperm and eggs. That matters because genetic changes occurring in germ cells can potentially be passed to offspring.

If BC200 is genuinely capable of moving within these cells, new insertions could theoretically become part of the inherited genome.

That does not mean BC200 is constantly jumping around human DNA. The researchers are still trying to determine how often such movements occur and under what circumstances they happen.

How did a human gene end up inside a virus?

The most unexpected part of the research came from a different genome altogether.

Scientists discovered BC200 embedded in molluscum contagiosum virus (MCV), a poxvirus that causes a common skin infection.

That immediately raised a striking possibility: could BC200 have moved from a human cell into the virus?

The researchers believe this may have happened while MCV was infecting human skin cells. Molluscum contagiosum is particularly relevant because the virus is known to infect skin, providing a plausible environment in which genetic material from a human cell could potentially become incorporated into the viral genome.

This would not be the first example of a mobile genetic element moving into a virus.

Scientists have observed similar events in other organisms. In one notable example from the late 1980s, researchers working with cultured moth cells saw a transposon move from the cells into a baculovirus, a virus that infects insects.

The Cornell finding is different because BC200 is a human and primate-associated genetic element.

Its presence in MCV gives researchers a rare opportunity to study whether a human-derived mobile element can move between a host genome and a virus.

The discovery also raises a more provocative question: if BC200 can enter a viral genome, could the virus itself use the gene for some purpose?

That possibility has not been established. Cornell researchers say they want to determine whether MCV has incorporated BC200 by chance or whether the viral genome gains some advantage from carrying it.

Could a jumping brain gene be linked to disease?

BC200's ability to move could become particularly important if researchers find evidence that it remains active in human cells.

Transposons have long been studied in connection with genetic instability and disease. An insertion into the wrong part of a genome can potentially disrupt genes or alter how they are regulated.

BC200 has already attracted attention because its expression appears to change in certain diseases.

The gene has been reported at unusually high levels in some tumours, including breast cancer, and researchers have also observed elevated BC200 expression in the brains of people with Alzheimer's disease.

These observations do not prove that BC200 causes either cancer or Alzheimer's disease.

A gene can become more active because of a disease without being responsible for starting it. Establishing a causal connection requires much more evidence.

The new study nevertheless gives scientists another question to investigate: is BC200 merely more active in diseased cells, or does it actually move more frequently through their genomes?

Cancer cells are particularly interesting because they often experience genomic instability. If BC200 were actively inserting itself into new locations in some tumours, researchers would want to know whether those insertions alter genes involved in cancer development.

The Cornell team plans to investigate this possibility, along with BC200's potential role in neurological disease.

The answers could help determine whether the gene's unusual mobility is simply an evolutionary leftover or whether it still has consequences in modern human cells.

Why the discovery matters for human evolution

The BC200 finding also offers a glimpse into how the human genome has been assembled over evolutionary time.

Nearly half of the human genome contains DNA derived from transposable elements. Most of those sequences are inactive today, but their evolutionary legacy is substantial.

Some have been discarded. Others have been silenced. A smaller number have been repurposed by evolution and incorporated into biological systems that benefit the organism.

BC200 represents an unusual possibility because it appears to occupy both categories.

It has become associated with a cellular function while retaining an ability inherited from its mobile ancestor.

That suggests evolution does not always force a clean choice between “useful gene” and “mobile DNA”.

In this case, the two properties may have survived together.

The discovery also shows why viruses can be useful windows into genome evolution. Viral genomes can capture pieces of genetic material from their hosts, providing clues about what has moved between organisms over time.

Finding a human-derived mobile element inside a virus gives researchers another way to investigate the movement of DNA between genomes.

For now, the biggest mystery is not simply where BC200 came from. Scientists already have a strong idea of its transposon ancestry.

The more difficult question is what BC200 is doing now.

If it continues to move through human DNA, researchers need to determine how frequently that happens, which cells permit it, what controls its movement and whether those insertions have any biological consequences.

Those questions could determine whether BC200 is simply an unusual relic of human evolution or an active participant in the biology of the brain and disease.

Frequently Asked Questions

What is BC200?
BC200 is a human genetic element found predominantly in neurons. It originated millions of years ago from a transposon, or mobile genetic element, and is thought to have a role in regulating processes involving messenger RNA in brain cells.

What are jumping genes?
Jumping genes, scientifically known as transposons, are DNA sequences capable of changing their position within a genome. Some can make copies of themselves and insert those copies elsewhere. Transposon-derived DNA makes up a substantial portion of the human genome.

How did scientists find BC200 inside a virus?
Researchers studying human genetic material found a copy of BC200 in the genome of molluscum contagiosum virus, a poxvirus that infects human skin. They believe the sequence may have entered the virus while it was infecting human cells, although the precise mechanism remains under investigation.

Does BC200 cause cancer or Alzheimer's disease?
There is currently no evidence that BC200 directly causes either condition. Researchers have observed abnormal or elevated BC200 expression in some tumours and in brains affected by Alzheimer's disease. The new research raises the possibility that its mobility could be relevant to disease, but that remains to be established.