Derivation of genetic interaction networks from quantitative phenotype data

Abstract

We have generalized the derivation of genetic-interaction networks from quantitative phenotype data. Familiar and unfamiliar modes of genetic interaction were identified and defined. A network was derived from agar-invasion phenotypes of mutant yeast. Mutations showed specific modes of genetic interaction with specific biological processes. Mutations formed cliques of significant mutual information in their large-scale patterns of genetic interaction. These local and global interaction patterns reflect the effects of gene perturbations on biological processes and pathways.

Figure 1

Application of the method to yeast agar invasion data to derive a genetic-interaction network. (a) Pre-wash and post-wash images of example genotypes in a yeast agar-invasion assay. (b) The invasion data shown on a phenotype axis with replicate-measurement error ranges, as a phenotype inequality, as a genetic-interaction mode, and as a graphical visualization. (c) Part of the network (only transcription factor genes) is shown. Nodes represent perturbed genes; edges represent genetic interactions. A key to the interactions is given in (d). (d) Graphical visualizations of genetic interaction modes and asymmetries, and example phenotype inequalities.

Figure 2

Gene perturbations show specific modes of genetic interaction with biological processes. (a) PBS2 deletion interacts additively with mutations of small-GTPase-mediated signal transduction genes. (b) PHD1 overexpression is hypostatic to deletions of invasive-growth genes. (c) ISW1 deletion suppresses the effects of perturbations of small-GTPase-mediated signal transduction genes. Key to interactions as in Figure 1d

Figure 3

Mutually informative genes show large-scale patterns of genetic interaction. Genetic interactions of STE12 and STE20 overexpressers. Key to interactions as in Figure 1d.

Figure 4

Networks of mutual information in patterns of genetic interaction show cliques. Nodes represent perturbed genes (see Additional data file 2). gf indicates a gain-of-function allele; lf indicates a loss-of-function allele. Edges connect gene pairs with significant mutual information in their patterns of genetic interaction (see Additional data file 6).