Umeå scientist presents discoveries about natural immunity in Science

A team including scientists at UCMP (Umeå Center for Molecular Pathogenesis), a research unit at Umeå University, shows in last week’s issue of the journal Science that the protein PGRP-LC plays a crucial role in so-called innate immunity.

Professor Dan Hultmark, post-doctoral fellow Svenja Stöven, and doctoral candidate Thomas Werner at UCMP are focusing their attention on the mechanisms behind natural, or innate, immunity, and they are using the fruit-fly, Drosophila melanogaster, as a model system. The aim is, one the one hand, the better to understand the corresponding system in humans and, on the other hand, the fact that immunity in insects is itself important, mainly because a large number of diseases are spread by insect vectors.

When insects are infected by bacteria or fungi they react by producing effective antidotes in the form of special proteins and peptides that kill the invaders. This natural immune defense is triggered by substances from the invaders’ cell walls.

One such triggering factor is peptidoglycan, but little has been known about just how it is recognized by the immune defense system. In this article the UCMP team, in collaboration with researchers from the Sloan-Kettering Institute and Cornell University, have been able to show that the protein PGRP-LC plays a key role. They found that this protein switches on the immune defense system by activating a transcription factor, “Relish,” which was previously discovered by Dan Hultmark’s team. PGRP-LC belongs to a family of “PEPTIDOGLYCAN Recognition Proteins” (PGRP) that bind to peptidoglycan. PGRP was first discovered in butterflies, and interestingly enough there is an equivalent in humans as well.