title: DTNI: a novel toxicogenomics data analysis tool for identifying the molecular mechanisms underlying the adverse effects of toxic compounds.
abstract: Unravelling gene regulatory networks (GRNs) influenced by chemicals is a major challenge in systems toxicology. Because toxicant-induced GRNs evolve over time and dose, the analysis of global gene expression data measured at multiple time points and doses will provide insight in the adverse effects of compounds. Therefore, there is a need for mathematical methods for GRN identification from time-over-dose-dependent data. One of the current approaches for GRN inference is Time Series Network Identification (TSNI). TSNI is based on ordinary differential equations (ODE), describing the time evolution of the expression of each gene, which is assumed to be dependent on the expression of other genes and an external perturbation (i.e. chemical exposure). Here, we present Dose-Time Network Identification (DTNI), a method extending TSNI by including ODE describing how the expression of each gene evolves with dose, which is supposed to depend on the expression of other genes and the exposure time. We also adapted TSNI in order to enable inclusion of time-over-dose-dependent data from multiple compounds. Here, we show that DTNI outperforms TSNI in inferring a toxicant-induced GRN. Moreover, we show that DTNI is a suitable method to infer a GRN dose- and time-dependently induced by a group of compounds influencing a common biological process. Applying DTNI on experimental data from TG-GATEs, we demonstrate that DTNI provides in-depth information on the mode of action of compounds, in particular key events and potential molecular initiating events. Furthermore, DTNI also discloses several unknown interactions which have to be verified experimentally.
authors.affiliation: Department of Toxicogenomics, GROW-School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 40, 6229 ER, Maastricht, The Netherlands. d.hendrickx@maastrichtuniversity.nl.|, P.O. Box 616, 6200 MD, Maastricht, The Netherlands. d.hendrickx@maastrichtuniversity.nl.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Hendrickx
authors.affiliation: Department of Toxicogenomics, GROW-School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 40, 6229 ER, Maastricht, The Netherlands.|, P.O. Box 616, 6200 MD, Maastricht, The Netherlands.
authors.forename: Terezinha
authors.initials: T
authors.lastname: Souza
authors.affiliation: Department of Toxicogenomics, GROW-School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 40, 6229 ER, Maastricht, The Netherlands.|, P.O. Box 616, 6200 MD, Maastricht, The Netherlands.
authors.forename: Danyel G J
authors.initials: DGJ
authors.lastname: Jennen
authors.affiliation: Department of Toxicogenomics, GROW-School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 40, 6229 ER, Maastricht, The Netherlands.|, P.O. Box 616, 6200 MD, Maastricht, The Netherlands.
authors.forename: Jos C S
authors.initials: JCS
authors.lastname: Kleinjans
mesh_terms: D000465:Algorithms; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology / Q000235:genetics; D003198:Computer Simulation; D004305:Dose-Response Relationship, Drug; D064420:Drug-Related Side Effects and Adverse Reactions / Q000209:etiology / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects*; D053263:Gene Regulatory Networks / Q000187:drug effects*; D015386:Hazardous Substances / Q000633:toxicity*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D012044:Regression Analysis; D015203:Reproducibility of Results; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013997:Time Factors; D043922:Toxicogenetics / Q000379:methods*
chemical_list: D015386:Hazardous Substances
keywords: Dose–response; Gene regulatory network inference; Key event; Mode of action; Molecular initiating event; Time series