Most Deadly mushroom poison might now have an antidote — with help from CRISPR

Good news! What will be next? Eat more mushrooms! 

It appears the antidote needs some refinement: 50% of mice still died.

"...  researchers recently identified a potential antidote, they also zeroed in on the biochemical pathway in humans that’s necessary for the mushrooms’ toxin — called α-amanitin — to enter cells. The antidote, a chemical named indocyanine green, interrupts that pathway. ...

They first used CRISPR-Cas9 gene-editing technology to create a pool of human cells, each with a mutation in a different gene. They then tested which mutations helped the cells to survive exposure to α-amanitin.

This ‘CRISPR-Cas9 screen’ revealed that cells lacking a functional version of an enzyme called STT3B are able to survive α-amanitin. STT3B is part of a biochemical pathway that adds sugar molecules to proteins. Interrupting this pathway somehow blocks α-amanitin from entering cells, preventing the toxin from fully wreaking havoc. ...
The second step in the researchers’ strategy had them sifting through about 3,200 chemical compounds, looking for one that would block the action of STT3B. Among those compounds, they uncovered indocyanine green, a dye developed by the photography company Kodak in the 1950s that has since been used in medical imaging, for example, to visualize blood vessels in the eye and blood flow in the liver. Only about 50% of mice treated with indocyanine green died from α-amanitin poisoning, compared with 90% of those that were not treated. ..."

From the abstract:

"The “death cap”, Amanita phalloides, is the world’s most poisonous mushroom, responsible for 90% of mushroom-related fatalities. The most fatal component of the death cap is α-amanitin. Despite its lethal effect, the exact mechanisms of how α-amanitin poisons humans remain unclear, leading to no specific antidote available for treatment. Here we show that STT3B is required for α-amanitin toxicity and its inhibitor, indocyanine green (ICG), can be used as a specific antidote. By combining a genome-wide CRISPR screen with an in silico drug screening and in vivo functional validation, we discover that N-glycan biosynthesis pathway and its key component, STT3B, play a crucial role in α-amanitin toxicity and that ICG is a STT3B inhibitor. Furthermore, we demonstrate that ICG is effective in blocking the toxic effect of α-amanitin in cells, liver organoids, and male mice, resulting in an overall increase in animal survival. Together, by combining a genome-wide CRISPR screen for α-amanitin toxicity with an in silico drug screen and functional validation in vivo, our study highlights ICG as a STT3B inhibitor against the mushroom toxin."

Deadly mushroom poison might now have an antidote — with help from CRISPR Gene-editing technique might have finally cracked the mystery of how death cap mushrooms kill.

Identification of indocyanine green as a STT3B inhibitor against mushroom α-amanitin cytotoxicity (open access)

Fig. 2: The CRISPR screen identifies genes and pathways required for AMA toxicity