Borden Lacy
Last active: 3/24/2020

Small Molecule Inhibitor Screen Reveals Calcium Channel Signaling as a Mechanistic Mediator of TcdB-Induced Necrosis.

Farrow MA, Chumber NM, Bloch SC, King M, Moton-Melancon K, Shupe J, Washington MK, Spiller BW, Lacy DB
ACS Chem Biol. 2020 15 (5): 1212-1221

PMID: 31909964 · PMCID: PMC7230009 · DOI:10.1021/acschembio.9b00906

is the leading cause of nosocomial diarrhea in the United States. The primary virulence factors are two homologous glucosyltransferase toxins, TcdA and TcdB, that inactivate host Rho-family GTPases. The glucosyltransferase activity has been linked to a "cytopathic" disruption of the actin cytoskeleton and contributes to the disruption of tight junctions and the production of pro-inflammatory cytokines. TcdB is also a potent cytotoxin that causes epithelium necrotic damage through an NADPH oxidase (NOX)-dependent mechanism. We conducted a small molecule screen to identify compounds that confer protection against TcdB-induced necrosis. We identified an enrichment of "hit compounds" with a dihydropyridine (DHP) core which led to the discovery of a key early stage calcium signal that serves as a mechanistic link between TcdB-induced NOX activation and reactive oxygen species (ROS) production. Disruption of TcdB-induced calcium signaling (with both DHP and non-DHP molecules) is sufficient to ablate ROS production and prevent subsequent necrosis in cells and in a mouse model of intoxication.

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