Newly Discovered Protein Sounds the Alarm on Invading Pathogens

Researchers have discovered a previously unknown protein that plays a key role in notifying the immune system when a bacteria virus has entered a cell. The researchers who made the discovery believe this protein could one day be manipulated either to treat infection by increasing its expression or dampen the effects of autoimmune disorders by decreasing its expression. Their research is published in Nature Microbiology.

For the study, researchers from the Department of Biomedicine at Aarhus University, Denmark cultured cells exposed to listeria bacteria. This allowed them to observe in a petri dish how the attacking listeria bacteria penetrated the cell, depositing a small amount of their DNA. The DNA was distributed into the cytoplasm where the protein cGAS discovered the foreign DNA and, along with the signaling protein STING, sent alarm signals into the cell.

Here, the previously unknown messenger came into play. This protein, MVB12b, packages and exports the DNA fragments in exosomes. These exosomes are sent to neighboring cells to mount a defense before the cells become infected.

Next, the researchers introduced listeria bacteria into mice with blocked exosome signaling. These mice were unable to spread the immune signal and send an alarm that the tissue needed protecting.

Dampening this signaling could someday used to treat autoimmune disorders, such as Lupus. In addition, the researchers believe doing the reverse—heightening the signaling—could be a way to increase immune response and get the body to mount a better response against invading pathogens.