Research Article

Haploid Genetic Screens in Human Cells Identify Host Factors Used by Pathogens

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Science  27 Nov 2009:
Vol. 326, Issue 5957, pp. 1231-1235
DOI: 10.1126/science.1178955

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“Haploid Human”

Genetic screens can provide direct insight into biological processes that are poorly understood. Carette et al. (p. 1231) describe genetic screens using large-scale gene disruption in human cells haploid for all chromosomes except for chromosome 8. One screen was used to identify host factors essential for the activity of cytolethal distending toxin, a toxin found in several pathogenic bacteria. Another screen identified host gene products essential for infection with influenza, and an additional screen revealed genes required for the action of adenosine 5′-diphosphate (ADP)–ribosylating bacterial toxins. This loss-of-function genetic approach in mammalian cells will be widely applicable to study a variety of biological processes and cellular functions.


Loss-of-function genetic screens in model organisms have elucidated numerous biological processes, but the diploid genome of mammalian cells has precluded large-scale gene disruption. We used insertional mutagenesis to develop a screening method to generate null alleles in a human cell line haploid for all chromosomes except chromosome 8. Using this approach, we identified host factors essential for infection with influenza and genes encoding important elements of the biosynthetic pathway of diphthamide, which are required for the cytotoxic effects of diphtheria toxin and exotoxin A. We also identified genes needed for the action of cytolethal distending toxin, including a cell-surface protein that interacts with the toxin. This approach has both conceptual and practical parallels with genetic approaches in haploid yeast.

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