Researchers have identified BC200—a human gene active in neurons—inside the molluscum contagiosum virus, revealing that a gene can maintain a cellular biological function while retaining its transposable, jumping ability.
Viral Capture of a Primate Gene
Pieces of human DNA capable of copying themselves into new locations have turned up inside a virus. Researchers discovered two distinct sequences derived from the BC200 gene inside the molluscum contagiosum virus, a pathogen that infects human skin and causes small, raised lesions. The findings show an unusual genetic double life where BC200 acquired a cellular role millions of years ago while retaining the capacity to produce copies that insert themselves elsewhere.
This marks the first time scientists have identified a human gene serving an important biological role while keeping the ability to move around the genome. Cedric Feschotte, a senior author of the study at Cornell University’s Department of Molecular Biology and Genetics, stated in a university release, Somehow evolution hasn’t been able to untangle these two things.
Feschotte noted that genes repurposed from transposable elements for cellular functions typically lose their mobility, making the survival of both traits in BC200 exceptional.
Evolutionary Origins and Mechanisms of Movement
The predecessor of BC200 established itself in a common ancestor of monkeys and apes roughly 35 to 55 million years ago. Around 40 million years ago, the sequence was recruited for a cellular role, regulating protein production in neurons. Once a gene becomes useful, its mobility should normally decrease, locking it into a fixed genomic position. Instead, the gene kept moving.
Available poxvirus genomes were examined for sequences resembling mobile genetic elements by a research team that featured investigators from the University of Texas at Arlington as well as Capital Normal University in China.
Analysis pointed to two separate transfer events rather than a single insertion that later duplicated inside the virus. Because BC200 lacks transport machinery of its own, researchers believe it hitched a ride on LINE-1—another mobile genetic element capable of producing the molecular machinery required to copy RNA into DNA and insert it into a genome.
Virus Infection Increases BC200 Expression in Human Cells
While BC200 RNA is particularly abundant in neurons, it is also expressed at low levels in skin cells. Researchers observed increased BC200 expression in cultured human fibroblasts infected with the virus, suggesting that an active infection might help create the cellular conditions necessary for transfer.
The research team identified hundreds of copies of this gene over the course of evolution in different primates. BC200 also appears at low levels in germ cells, including sperm and eggs, indicating a potential to create new insertions that could be inherited by future generations. Scientists have focused greater scrutiny on this gene because its levels are abnormally high in certain tumors alongside elevated concentrations observed within the brains of Alzheimer’s disease patients.
Future Questions Regarding Viral Infection and Disease
Whether the virus benefits from the acquired sequence remains uncertain.
Researchers now want to determine whether the virus exploits this sequence to modify the cells it infects, while also investigating the activity of BC200 in cancer cells where it is abnormally present to see if its movements can generate new mutations.
