Screening of a Drug Library Identifies Inhibitors of Cell Intoxication by CNF1

Area of Science:

• Microbiology
• Toxicology
• Pharmacology

Background:

• Cytotoxic necrotizing factor 1 (CNF1) from pathogenic Escherichia coli causes extra-intestinal infections.
• CNF1 permanently activates Rac1 by deamidation, leading to inflammation and Rac1 proteasomal degradation.
• No specific therapies currently exist for CNF1 toxicity.

Purpose of the Study:

• To screen for inhibitors of CNF1-induced Rac1 degradation using a cell-based immunoassay.
• To identify approved drugs that can counteract CNF1 effects.
• To explore drug repurposing for CNF1-related diseases and bacterial infections.

Main Methods:

• Development of a fluorescent cell-based immunoassay.
• Screening of 1120 approved drugs for inhibitors of CNF1-induced Rac1 degradation.
• Assessment of protective effects against CNF1-induced multinucleation and diphtheria toxin.

Main Results:

• Eleven compounds inhibited CNF1-induced Rac1 degradation.
• Five of these compounds also protected cells from CNF1-induced multinucleation.
• Four compounds (lasalocid, monensin, bepridil, amodiaquine) protected cells against both CNF1 and diphtheria toxin.

Conclusions:

• Drug repurposing offers a viable strategy to combat CNF1 infections.
• Identified compounds show potential as therapeutics for bacterial infections and Rac1-mediated diseases.
• Further investigation into these drugs could lead to novel treatments.