Alpha Amanitin

choi

Wang B et al, Identification of Indocyanine Green as a STT3B Inhibitor Against Mushroom α-Amanitin Cytotoxicity. Nat Commun (short for Nature Communications, a journal) 14: 2241 (2023).
https://www.nature.com/articles/s41467-023-37714-3

Note:
(a) This article was reported in
Alla Katsnelson, Inklings of an Antidote to Deadly Mushroom; Researchers find clues to a potential remedy for ingesting a variety of poisonous species. New York Times, May 30, 2023, at page D5 (every Tuesday, section D is ScienceTimes)
https://www.nytimes.com/2023/05/ ... h-cap-mushroom.html
https://www.dtnext.in/edit/2023/ ... poisonous-mushrooms
("A mushroom called the death cap -- Amanita phalloides -- [contains] toxin alpha amanitin [that] accounts for the vast majority of mushroom-poisoning deaths. * * * There is no antidote * * * Alpha amanitin wreaks havoc on the body by mucking up the cells' ability to make messenger RNA[, without which, there is no making of proteins]. * * * Qiaoping Wang, a pharmacologist and toxicologist at Sun Yat-sen University in Shenzhen, China. * * * The researchers [led by Wang] first used CRISPR, the gene-editing technology, to create human cells with thousands of specific genes knocked out, one by one. They then swamped the cells with alpha amanitin and tracked which ones continued to thrive. * * * They narrowed in on one gene, STT3B [whose deactivation -- or knockout in molecular genetics (borrowed from boxing) -- led the cell containing the mutation to survive amanitin], that seemed especially critical to toxicity.  Next, the researchers used computer modelling to search for compounds approved by the US Food and Drug Administration that might block STT3B, coming up with 34 possible drugs. All but one fell away in further tests on cells. The remaining compound, called indocyanine green (ICG), is a dye widely used to take images of liver and heart function. When Dr Wang and his team injected the toxin into mice, followed by ICG, the animals’ recovery improved and the liver damage decreased significantly.  'The exact mechanism is still unknown,' Dr Wang said. But his team’s work so far suggests that the STTB3 gene somehow helps alpha amanitin enter cells, and that ICG prevents this step")

There is no need to read the rest of the NYT report.

(b) The last author if the Nature Communications article is Qiaoping Wang  王巧平教授. His Web page atthe university indicates:
"2017年10月任药学院（深圳）'百人计划' 教授、博导。 * * *
2011-2017年，澳大利亚Garvan 医学研究所及悉尼大学博士后。 * * *
2005-2010      理学博士, 中山大学和伦敦大学卫生与热带医学学院
2001-2005      理学学士，四川农业大学"
https://yxysz.sysu.edu.cn/zh-hans/node/243
(c) α-Amanitin
https://en.wikipedia.org/wiki/Α-Amanitin
("is a cyclic peptide of eight amino acids")

(d) I will return to the Nature article at the top pf this posting.

Its "Results" section starts: " * * * To identify the key genes and pathways required for AMA [Wang's acronym for α-Amanitin]-induced cell death, we carried out a genome-wide loss-of-function screen that targets a total of 19,114 genes using the human CRISPR knockout pooled library (Brunello). We performed our screening using haploid cell line HAP1, which has been extensively used" in research)
(i) There is no need to read the rest of this article.
(ii) HAO-1 is a cell line (derived from human cancer) that has one of each of 23 pairs of chromosomes -- hence HAP (short for haploid) as the name of the cell line. (A cell line means the cells may propagate, or divide, forever.)
(iii) What is "a genome-wide loss-of-function screen"?
(A) The "loss-of-function" (of a gene, and hence its intended protein) is another way to say knockout.
(B) CRISPR
https://en.wikipedia.org/wiki/CRISPR
is found in bacteria. It is DNA fragment from bacteriophage that had infected the ancestor of the bacteria that the ancestor had successfully killed and then retained the remnant to compare with the DNA of future bacteriophage invasions. If found similar, bacteria will destroy future invasions with DNA nucleases produced by bacteria. Different groups of bacteria produced different DNA nucleases, the most commonly used is Cas9 (short for "CRISPR-associated protein 9"). These DNA nucleases will require three nucleotides NGG (where N stands for any of the four deoxy nucleotides that makes up DNA) in 5' to 3' direction. These DNA nucleases will require synthetic "guide RNA" to direct these DNA nucleases to the exact site of DNA in the whole nucleus, to make a double-strand break of the DNA, these DNA nucleases comparing guide RNA with DNA sequences of the entire nucleus.   

(e) Methodology is not new in this research, but the finding on the toxin is new.