Scientists Discover New Function of Cells in Our Immune System
Scientists knew about the proteasome, but they didn't know they could do this.
Hiya!
I used to think we’d discovered everything we needed to know. Then I learned we have no idea how much we don’t know. Even when we think we know everything about something, a new discovery inevitably changes everything we thought we knew.
For instance, we understand our immune system pretty well, but scientists just discovered a new role for the trash bins of our cells: the proteasome. This finding could revolutionize the medical field by providing a new source of antibiotics while also potentially solving our growing global antimicrobial drug resistance problem.
The Proteasome
The research we’re discussing today focuses on the proteasome — a structure inside every cell within a body — which takes up about 1 to 2 percent of a cell’s protein content.
Nicknamed our cellular trash bins, proteasomes are made of protein complexes that chop dead and aging proteins into smaller pieces, called peptides, which can be recycled into new proteins. All in all, proteasomes are responsible for breaking down about 70 percent of cellular proteins.
However, in the 1990s, researchers discovered peptides on the surface of cells that help the immune system identify threats, aka an infected cell. However, no one realized the extent of this responsibility until more recently thanks to technological advancements.
Several years ago, Professor Yifat Merbl and her colleagues at the Weizmann Institute of Science in Israel created an innovative technique using CRISPR technology that allowed them to investigate proteasomes in cells to reveal information about a cell’s function that is not otherwise seen.
(Fun fact: The Weizmann Institute of Science is a public research university established fourteen years before the State of Israel was founded.)
The team’s official name for their technique is Mass spectrometry Analysis of Proteolytic Peptides (MAPP). However, unofficially, they refer to it as “dumpster diving,” since they’re essentially rummaging through the body’s trash to look for information.
Using this method, the researchers tracked how proteasomes respond to various diseases, like cancer and lupus, while accumulating peptide degradation data.
It was then, Merbl explained in a news release by the Weizmann Institute, that:
“We took a broad look at all the data and asked ourselves: Could the products of the degradation play an additional role, beyond being presented to the immune system?”
According to their dumpster diving efforts, the team was surprised to learn that many of the degraded peptides matched ones previously identified as antimicrobial peptides — the body’s first line of defense against pathogens and a critical immune system component.
According to the World Health Organization,
“Antimicrobials – including antibiotics, antivirals, antifungals, and antiparasitics – are medicines used to prevent and treat infectious diseases in humans, animals and plants.”
For years, experts thought such antimicrobial peptides were made by protein-chopping enzymes called proteases. If proteasomes are responsible for breaking down protein structures into smaller pieces called peptides, proteases break down the peptides into their chemical components, like amino acids. However, Merbl and her team’s new findings suggest something else.