A whole-genome RNAi screen uncovers a novel role for human potassium channels in cell killing by the parasite Entamoeba histolytica.
The parasite Entamoeba histolytica kills human cells resulting in ulceration, inflammation and invasion of the colonic epithelium. We used the cytotoxic properties of ameba to select a genome-wide RNAi library to reveal novel host factors that control susceptibility to amebic killing. We identified 281 candidate susceptibility genes and bioinformatics analyses revealed that ion transporters were significantly enriched among susceptibility genes. Potassium (K(+)) channels were the most common transporter identified. Their importance was further supported by colon biopsy of humans with amebiasis that demonstrated suppressed K(+) channel expression. Inhibition of human K(+) channels by genetic silencing, pharmacologic inhibitors and with excess K(+) protected diverse cell types from E. histolytica-induced death. Contact with E. histolytica parasites triggered K(+) channel activation and K(+) efflux by intestinal epithelial cells, which preceded cell killing. Specific inhibition of Ca(2+)-dependent K(+) channels was highly effective in preventing amebic cytotoxicity in intestinal epithelial cells and macrophages. Blockade of K(+) efflux also inhibited caspase-1 activation, IL-1β secretion and pyroptotic death in THP-1 macrophages. We concluded that K(+) channels are host mediators of amebic cytotoxicity in multiple cells types and of inflammasome activation in macrophages.
Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA.
Chelsea
C
Marie
Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA.
Hans P
HP
Verkerke
Department of Surgery, Department of Pharmacology, University of Colorado Comprehensive Cancer Center, University of Colorado, Denver, CO, USA.
Dan
D
Theodorescu
Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA.
William A
WA
Petri
D000818:Animals; D002460:Cell Line; D019295:Computational Biology / Q000379:methods; D004748:Entamoeba histolytica / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D004847:Epithelial Cells / Q000378:metabolism / Q000469:parasitology; D005786:Gene Expression Regulation; D015723:Gene Library; D055106:Genome-Wide Association Study; D023281:Genomics / Q000379:methods; D059014:High-Throughput Nucleotide Sequencing; D057166:High-Throughput Screening Assays; D006790:Host-Parasite Interactions / Q000235:genetics*; D006801:Humans; D058847:Inflammasomes / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D008264:Macrophages / Q000378:metabolism / Q000469:parasitology; D035683:MicroRNAs / Q000235:genetics*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D015203:Reproducibility of Results
D058847:Inflammasomes; D035683:MicroRNAs; D026902:Potassium Channel Blockers; D015221:Potassium Channels