Exploring gene function and drug action using chemogenomic dosage assays

In this chapter, we describe a series of genome-wide, cell-based assays that provide a solid basis for understanding drug-gene interactions, gene function, and for defining the mechanism of action of small molecules. Each of these assays takes advantage of the ability to grow complex pools competitively and to use high-density microarrays that report the results of such screens. The assays described here take advantage of alterations in gene dosage of Saccharomyces cerevisiae, and include HIP (haploinsufficiency profiling), HOP (homozygous profiling), and MSP (multicopy suppression profiling) as genetic tools to understand gene function and drug mechanism. The common experimental theme is that, in each assay, strains are pooled and screened in parallel to investigate the relative contribution of each gene product to sensitivity or resistance to a drug or environmental perturbation across the genome in a single assay. Further, the compendium of results from these screens can inform large-scale network analysis of genetic function, gene-gene interactions, and mechanism of drug action.