If you’re anything like me (geek that I am), every new technological device tends to get your blood pumping and invokes an involuntary reflex to reach for your wallet. That’s even truer for the ever-popular “i”-products which tend to grab our collective-geek attention even faster with every new device. Now there are some clever scientists from the University of Bonn in Germany who have developed a new reporter system utilizing Gaussia luciferase, the “iGLuc”!
While researching the inflammasome process, and specifically IL-1β, a primary target of caspase-1, Bartok et al. hit a frustrating road block. Inflammasomes are large, multiprotein oligomers that are intregal parts of the immune response system. They are a platform which supports an inflammatory cascade after sensing damage-associated molecular patterns. Caspase-1 is an enzyme that’s utilized by the inflammasome cascade in order to proteolytically cleave specific proteins (such as IL-1β precursor) into active, mature peptides. Once cleaved, IL-1β can finally bind to its receptor in order to induce a variety of cellular responses, such as pyroptosis; a form of programmed cell death that is in response to inflammation.
Bartok was looking for a better way to analyze IL-1β. ELISA techniques were not sensitive enough to distinguish between the IL-1β precursors and mature IL-1β, and Western blotting was too time consuming and useless for high throughput analysis. So, instead they devised a fusion protein of pro-IL-1β and GLuc (Gaussia Luciferase) and called it iGLuc! Unexpectedly, they first saw virtually no luciferase signal from the fusion, even though they were seeing high expression levels of luciferase in the system. But they discovered that pro-IL-1β tends to form a protein aggregate which acts to restrict the release of the signaling C-terminal portion of GLuc. But with the simple addition of caspase-1, pro-IL-1β was cleaved and a corresponding bioluminescent signal could be measured.
The resulting process seems to make for an excellent reporter assay for inflammasome activity! Bartok tested the system both in vitro and in vivo and the system showed good sensitivity and specificity as well as a great signal to noise ratio. The system also shows a lot of promise that it can be further applied to other proteases as well! So, if you’re in the field of inflammasomes (or if you have to own every new device), be sure to keep an “i” out for the iGLuc system. It may become the next, best geeky thing on the technological front! You can find their complete article here.
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