title: Selective inhibitor of endosomal trafficking pathways exploited by multiple toxins and viruses.
abstract: Pathogenic microorganisms and toxins have evolved a variety of mechanisms to gain access to the host-cell cytosol and thereby exert virulent effects upon the host. One common mechanism of cellular entry requires trafficking to an acidified endosome, which promotes translocation across the host membrane. To identify small-molecule inhibitors that block this process, a library of 30,000 small molecules was screened for inhibitors of anthrax lethal toxin. Here we report that 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone, the most active compound identified in the screen, inhibits intoxication by lethal toxin and blocks the entry of multiple other acid-dependent bacterial toxins and viruses into mammalian cells. This compound, which we named EGA, also delays lysosomal targeting and degradation of the EGF receptor, indicating that it targets host-membrane trafficking. In contrast, EGA does not block endosomal recycling of transferrin, retrograde trafficking of ricin, phagolysosomal trafficking, or phagosome permeabilization by Franciscella tularensis. Furthermore, EGA does not neutralize acidic organelles, demonstrating that its mechanism of action is distinct from pH-raising agents such as ammonium chloride and bafilomycin A1. EGA is a powerful tool for the study of membrane trafficking and represents a class of host-targeted compounds for therapeutic development to treat infectious disease.
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA 90095.
authors.forename: Eugene J
authors.initials: EJ
authors.lastname: Gillespie
authors.forename: Chi-Lee C
authors.initials: CL
authors.lastname: Ho
authors.forename: Kavitha
authors.initials: K
authors.lastname: Balaji
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Clemens
authors.forename: Gang
authors.initials: G
authors.lastname: Deng
authors.forename: Yao E
authors.initials: YE
authors.lastname: Wang
authors.forename: Heidi J
authors.initials: HJ
authors.lastname: Elsaesser
authors.forename: Batcha
authors.initials: B
authors.lastname: Tamilselvam
authors.forename: Amandeep
authors.initials: A
authors.lastname: Gargi
authors.forename: Shandee D
authors.initials: SD
authors.lastname: Dixon
authors.forename: Bryan
authors.initials: B
authors.lastname: France
authors.forename: Brian T
authors.initials: BT
authors.lastname: Chamberlain
authors.forename: Steven R
authors.initials: SR
authors.lastname: Blanke
authors.forename: Genhong
authors.initials: G
authors.lastname: Cheng
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: de la Torre
authors.forename: David G
authors.initials: DG
authors.lastname: Brooks
authors.forename: Michael E
authors.initials: ME
authors.lastname: Jung
authors.forename: John
authors.initials: J
authors.lastname: Colicelli
authors.forename: Robert
authors.initials: R
authors.lastname: Damoiseaux
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Bradley
mesh_terms: D000588:Amines; D000818:Animals; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors*; D001692:Biological Transport / Q000502:physiology; D020170:Caspase 1 / Q000378:metabolism; D002853:Chromatography, Liquid; D011992:Endosomes / Q000187:drug effects* / Q000502:physiology; D005434:Flow Cytometry; D006367:HeLa Cells; D057166:High-Throughput Screening Assays / Q000379:methods*; D006801:Humans; D008264:Macrophages; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D015394:Molecular Structure; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology; D012664:Semicarbazones / Q000737:chemistry / Q000494:pharmacology*; D054852:Small Molecule Libraries; D013329:Structure-Activity Relationship; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D000588:Amines; D001427:Bacterial Toxins; C493330:Red DND-99; D012664:Semicarbazones; D054852:Small Molecule Libraries; C088211:4-bromobenzaldehyde semicarbazone; D020170:Caspase 1