A cholesterol-binding bacterial toxin provides a strategy for identifying a specific Scap inhibitor that blocks lipid synthesis in animal cells.
Proc Natl Acad Sci U S A
; 121(7): e2318024121, 2024 Feb 13.
Article
in En
| MEDLINE
| ID: mdl-38330014
ABSTRACT
Lipid synthesis is regulated by the actions of Scap, a polytopic membrane protein that binds cholesterol in membranes of the endoplasmic reticulum (ER). When ER cholesterol levels are low, Scap activates SREBPs, transcription factors that upregulate genes for synthesis of cholesterol, fatty acids, and triglycerides. When ER cholesterol levels rise, the sterol binds to Scap, triggering conformational changes that prevent activation of SREBPs and halting synthesis of lipids. To achieve a molecular understanding of how cholesterol regulates the Scap/SREBP machine and to identify therapeutics for dysregulated lipid metabolism, cholesterol-mimetic compounds that specifically bind and inhibit Scap are needed. To accomplish this goal, we focused on Anthrolysin O (ALO), a pore-forming bacterial toxin that binds cholesterol with a specificity and sensitivity that is uncannily similar to Scap. We reasoned that a small molecule that would bind and inhibit ALO might also inhibit Scap. High-throughput screening of a ~300,000-compound library for ALO-binding unearthed one molecule, termed UT-59, which binds to Scap's cholesterol-binding site. Upon binding, UT-59 triggers the same conformation changes in Scap as those induced by cholesterol and blocks activation of SREBPs and lipogenesis in cultured cells. UT-59 also inhibits SREBP activation in the mouse liver. Unlike five previously reported inhibitors of SREBP activation, UT-59 is the only one that acts specifically by binding to Scap's cholesterol-binding site. Our approach to identify specific Scap inhibitors such as UT-59 holds great promise in developing therapeutic leads for human diseases stemming from elevated SREBP activation, such as fatty liver and certain cancers.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Bacterial Toxins
/
Lipogenesis
Type of study:
Prognostic_studies
Limits:
Animals
/
Humans
Language:
En
Journal:
Proc Natl Acad Sci U S A
/
Proc. Natl. Acad. Sci. U. S. A
/
Proceedings of the national academy of sciences of the United States of America
Year:
2024
Document type:
Article
Country of publication:
Estados Unidos