Characterization of the Type 2 Diabetes associated KLF14 trans-regulatory network. K. Small1, L. Quaye1, A. Hough2, M. Todorcevic3, A. Mahajan4, M. Horikoshi4, A. Buil5, A. Vinuela1, C. Glastonbury1, A. Brown6, J. Bell1, A. Gloyn3, R. Cox2, F. Karpe3, M. McCarthy3,4 1) Department of Twin Research and Genetic Epidemiology, Kings College London, London, UK; 2) MRC Harwell, Oxford, UK,; 3) Oxford Centre for Diabetes, Endocrinology & Metabolism, University of Oxford, Oxford, UK; 4) Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK; 5) Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland; 6) Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, UK.
The region upstream of the maternally expressed transcription factor KLF14 is associated with Type 2 Diabetes (T2D) and HDL-cholesterol. The T2D association at KLF14 is complex - it is maternal-specific and shows evidence of female-specificity, which is supported by female-specific lipid associations to this region. We have previously shown that the T2D and HDL-associated variants at KLF14 mediate a maternal-specific trans-regulatory network in adipose tissue via cis-regulation of KLF14. We have extended our initial results from microarrays to multi-tissue RNAseq data from ~800 female twins from the TwinsUK cohort and identified an expanded network of 140 genes (FDR 5%) associated in trans to KLF14. KLF14 cis-regulation and the trans-regulatory network are adipose-specific: replicating in two adipose cohorts but not present in other key insulin action tissues such as muscle and liver, nor in skin, whole blood or brain tissues. In addition to regulation of mean expression levels, the KLF14 variants show evidence of trans-association with variance in expression levels (vQTL). There is a genome-wide enrichment for trans-vQTL (1 =0.13) in adipose, but no evidence of cis-vQTL with KLF14 expression itself (p= 0.3). We are investigating if the trans-vQTL effects are driven by gene-gene interaction between the KLF14 variants and SNPs in KLF14 binding sites of downstream genes. The KLF14 variants are associated with methylation of an Illumina HumanMethylation450 probe ~3KB upstream of KLF14 in adipose tissue (N = 603, p = 2.2e-7) but not whole blood (N = 217, p = 0.69) in the same cohort, indicating the cis-regulatory effect may be mediated by an adipose-specific epigenetic mechanism. The expanded set of trans-regulated genes show no enrichment for known pathways or biological processes, but are highly correlated with concurrently measured metabolic traits and enriched for variants directly associated to metabolic traits in large GWAS studies, including insulin levels, lipids and T2D. These associations highlight a subset of the trans-network that can independently influence disease and provide a novel biological link between disparate metabolic GWAS loci. Metabolic phenotyping of a KLF14 knockout mouse is ongoing, together with cellular phenotyping of adipocytes these studies will help inform how KLF14-dependent transcription events in adipose tissue play a critical role in the development of insulin resistance and predisposition to T2D.
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