Global analysis of the impact of environmental perturbation on cis-regulation of gene expression: DEX, 24hr

Genetic variants altering cis-regulation of normal gene expression (cis-eQTLs) have been extensively mapped in human cells and tissues, but the extent to which environmental perturbation influences such traits has not been studied to date. We carried out large-scale induction experiments using primary human bone cells derived from 113 unrelated donors of Swedish origin harvested under 18 different conditions (seven treatments, two vehicles, each assessed at two time points). The treatments with the largest impact on the transcriptome, verified on two independent expression arrays, included BMP-2 (t=2h), dexamethasone (DEX) (t=24h), and PGE2 (t=24h). Using these treatments, we performed expression profiling for 18,144 RefSeq transcripts applying biological replicates of the complete study cohort (ntotal=782) and combined it with genome-wide SNP-genotyping data in order to map treatment-specific cis-eQTLs. We found that 93% of cis-eQTLs at 1% FDR were replicated in at least one additional treatment and in fact, on average only 1.4% of the cis-eQTLs were considered as treatment-specific at high confidence. The relative invariability of cis-regulation following perturbation was reiterated independently by genome-wide allelic expression tests where only a small proportion of variance could be attributed to treatment, though treatment-specific cis-regulatory effects were 2-6-fold more abundant among up-or downregulated genes. We further followed-up and validated the DEX-specific cis-regulation of the MYO6 and TNC loci and found top cis-regulatory variants located 180 and 250kb upstream of the transcription start sites, respectively. Our results suggest that, as opposed to tissue-specificity of cis-eQTLs, the interaction between cellular environment and cis-variants are relatively rare (~1.5%), but that detection of such specific interactions can be achieved by combination of functional genomic tools.

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Grundberg E, Adoue V, Kwan T, Ge B, Duan QL, Lam KC, Koka V, Kindmark A, Weiss ST, Tantisira K, Mallmin H, Raby BA, Nilsson O, Pastinen T