Scientists discover a human brain gene that can jump through DNA

For the first time, scientists have identified a human gene that appears to serve an important biological role while still retaining the ability to move around the genome.

Researchers at Cornell University made the discovery after finding a human genetic element inside a poxvirus. Their analysis showed that the element, known as BC200, is not only associated with brain function but also behaves like a jumping gene, meaning it can move and insert itself into genomes.

A study published Sept. 24 in Science reports that BC200 combines traits that scientists had not previously seen together in a human gene.

A Brain Gene With a Mobile Past

BC200 is expressed mainly in neurons, but its evolutionary history traces back millions of years to a transposon, also known as a 'jumping gene', a non-coding genetic element capable of relocating itself and inserting into new places in a genome.

Transposons can sometimes be harmful because they are able to insert stretches of DNA into genes and interfere with normal function, potentially contributing to disease. Over evolutionary timescales, however, they can also be useful. Their activity can help regulate existing genes or contribute genetic material that eventually becomes part of new and beneficial genes.

About half of the human genome is made up of transposon-derived DNA. Most of these elements are no longer active, and only a very small fraction can still move and copy themselves within genomes.

"Genes that come from transposable elements and that are repurposed for cellular functions are typically no longer transposable," said Cedric Feschotte, a senior author of the study. "BC200 was itself created from a mobile element but has retained its mobility and yet it is also clearly serving a cellular function. Somehow evolution hasn't been able to untangle these two things."

A Rare Genetic Jump Into a Virus

Scientists have documented a handful of cases in other species in which transposable elements moved into viruses. One early example came in the late 1980s, when researchers working with cultured moth cells observed a transposon moving from those cells into a baculovirus, a type of virus that infects insects.

BC200, however, is found only in humans and closely related primates. Scientists first identified it in the late 1980s as a highly abundant non-coding RNA in human neurons.

Its exact physiological role remains uncertain, but evidence suggests that BC200 may help regulate how neuronal messenger RNAs are translated into proteins.

BC200 also appears at low levels in germ cells - sperm and eggs - which means it may have the potential to create new insertions in the genome that could be inherited by future generations.

Possible Links to Skin Cells and Disease

The researchers also think BC200 may have made its jump into the molluscum contagiosum virus (MCV) while the virus was infecting skin cells, since those are the only cells known to be infected by MCV.

The gene has also attracted attention because it is expressed abnormally in some tumors and appears at elevated levels in the brains of people with Alzheimer's disease. That raises the possibility that BC200's ability to move could also play a role in disease.

Feschotte said the team now wants to investigate whether the molluscum contagiosum virus uses BC200 to manipulate human host cells for its own benefit.

The researchers are also interested in learning more about BC200's connection to diseases such as breast cancer and other tumors, where the gene is abnormally expressed. One key question is whether BC200 is actively jumping in cancer cells and, if so, whether those movements are creating mutations.