Project description:Background: Expression quantitative trait loci (eQTL) studies are a valuable approach for identifying genetic variants correlated with gene expression. However, identifying the causal variants is challenging due to linkage disequilibrium amongst variants in the same haplotype block. In this study, we aim to identify functional SNPs in key regulatory regions that alter transcriptional regulation and thus, potentially impact cellular function. The majority of disease-associated single-nucleotide polymorphisms (SNPs) are located in regulatory regions, which can result in allele-specific binding (ASB) of transcription factors and differential expression of the target gene alleles. Here, we present regSNPs-ASB, a generalized linear model-based approach to accurately identify regulatory SNPs that are located in transcription factor binding sites from ATAC-seq data. Results: Using regSNPs-ASB, we identified 53 regulatory SNPs in human MCF-7 breast cancer cells and 125 regulatory SNPs in human mesenchymal stem cells (MSC). By integrating the regSNPs-ASB output with RNA-seq experimental data and publicly available chromatin interaction data from MCF-7 cells, we found that these 53 regulatory SNPs were associated with 74 potential target genes and that 32 (43%) of these genes showed significant allele-specific expression (ASE). By comparing all of the MCF-7 and MSC regulatory SNPs to the eQTLs in the Genome-Tissue Expression (GTEx) Project database, we found that 30% (16/53) of the regulatory SNPs in MCF-7 and 43% (52/122) of the regulatory SNPs in MSC were also eQTLs. The enrichment of regulatory SNPs in eQTLs indicated that many of them are likely responsible for allelic differences in gene expression (chi-square test, p-value < 0.01). In sum, we conclude that regSNPs-ASB is a useful tool for identifying causal variants from ATAC-seq data. This new computational tool will enable efficient prioritization of genetic variants identified as eQTL for further studies to validate their causal regulatory function. Ultimately, identifying causal genetic variants will further our understanding of the underlying molecular mechanisms of disease and the eventual development of potential therapeutic targets.
Project description:Genome-wide association studies (GWAS) have identified thousands of single nucleotide polymorphisms (SNPs) associated with different human phenotypes. Most SNPs are located in non-coding regions of the genome, where a small subset of causal SNPs is thought to contribute to risk by regulating transcription. However, identification of such causal variants remains challenging due to linkage disequilibrium, where blocks of SNPs are inherited together. Here, we performed a massively parallel reporter assay called survey of regulatory elements (SuRE) in human neural stem cells to assess the transcription regulatory potential of 7.1 million SNPs. We identified 7,002 SNPs with regulatory potential (reporter assay quantitative trait loci, raQTLs), thereby increasing the number of putative regulatory variants in neural cell types by one order of magnitude. raQTLs were enriched for enhancers and often coincide with binding sites for transcription factors, such as ZBTB33, YY1, and ETS factors. Overlapping SuRE data with eQTL data pinpointed likely gene-regulatory variants. Overlap with GWAS for seven neuropsychiatric phenotypes identified 187 raQTLs in risk loci containing 183,186 SNPs assessed by SuRE. In conclusion, our SuRE dataset provides a rich source to prioritize genetic variants that may be relevant for disease.
Project description:ApoC-III is a proatherogenic protein associated with elevated triglycerides; its deficiency is associated with reduced atherosclerosis. Mixed dyslipidemia, characterized by elevated triglyceride and apoC-III levels and low HDL cholesterol level, with or without elevated LDL cholesterol, increases cardiovascular disease risk and is commonly treated with combined statin and fibrate therapy. We sought to identify single nucleotide polymorphisms (SNPs) associated with apoC-III level response to combination therapy with statins and fenofibric acid (FA) in individuals with mixed dyslipidemia. Participants in a multicenter, randomized, double-blind, active-controlled study examining response to FA alone and in combination with statin were genotyped for candidate SNPs. Association between genotyed SNPs and APOC3 response to therapy was conducted
Project description:ApoC-III is a proatherogenic protein associated with elevated triglycerides; its deficiency is associated with reduced atherosclerosis. Mixed dyslipidemia, characterized by elevated triglyceride and apoC-III levels and low HDL cholesterol level, with or without elevated LDL cholesterol, increases cardiovascular disease risk and is commonly treated with combined statin and fibrate therapy. We sought to identify single nucleotide polymorphisms (SNPs) associated with apoC-III level response to combination therapy with statins and fenofibric acid (FA) in individuals with mixed dyslipidemia. Participants in a multicenter, randomized, double-blind, active-controlled study examining response to FA alone and in combination with statin were genotyped for candidate SNPs. Association between genotyed SNPs and APOC3 response to therapy was conducted We sought to identify single nucleotide polymorphisms (SNPs) associated with apoC-III level response to combination therapy with statins and fenofibric acid (FA) in individuals with mixed dyslipidemia. Participants in a multicenter, randomized, double-blind, active-controlled study examining response to FA alone and in combination with statin were genotyped for candidate SNPs. Genomic DNA extracted from peripheral blood was genotyped using a custom GoldenGate bead array encompassing 384 SNPs (Illumina). Multivariate linear regression and 2-way ANOVA for percent change in apoC-III level were performed between the groups receiving FA alone compared with FA+statin compared with statin alone.
Project description:We profiled androgen receptor (AR) genomic targets using high-throughput sequencing of chromatin-immunoprecipitated (ChIP) DNA from TMPRSS2-ERG fusion gene positive DUCaP prostate cancer cells. ChIp-seq and microarray gene expression profiling datasets were integrated with the NHGRI GWAS PCa risk SNPs catalog to identify disease susceptibility SNPs localized within functional androgen receptor binding sites (ARBSs). Eighty GWAS index or linked SNPs were found to be localized in ARBSs. Among these rs11891426:T>G in the 7th intron of the melanophilin gene was found located within a novel putative auxiliary AR binding motif, which we found enriched in the neighborhood of canonical androgen responsive elements. T→G exchange attenuated the transcriptional activity of the ARBS in an AR reporter gene assay of prostate cancer cell models. It went also in line with decreased melanophilin protein level in primary prostate tumors with G allele.These results unravel a hidden link between androgen receptor and a functional PCa risk SNP, whose allele alteration affects androgen regulation of its host gene melanophilin . Genomic profile of androgen receptor binding sites of androgen or vehicle treated DUCaP cells using ChIP-seq. IgG precipiated DNAs from both treatments served as controls.
Project description:We profiled androgen receptor (AR) genomic targets using high-throughput sequencing of chromatin-immunoprecipitated (ChIP) DNA from TMPRSS2-ERG fusion gene positive DUCaP prostate cancer cells. ChIp-seq and microarray gene expression profiling datasets were integrated with the NHGRI GWAS PCa risk SNPs catalog to identify disease susceptibility SNPs localized within functional androgen receptor binding sites (ARBSs). Eighty GWAS index or linked SNPs were found to be localized in ARBSs. Among these rs11891426:T>G in the 7th intron of the melanophilin gene was found located within a novel putative auxiliary AR binding motif, which we found enriched in the neighborhood of canonical androgen responsive elements. T→G exchange attenuated the transcriptional activity of the ARBS in an AR reporter gene assay of prostate cancer cell models. It went also in line with decreased melanophilin protein level in primary prostate tumors with G allele.These results unravel a hidden link between androgen receptor and a functional PCa risk SNP, whose allele alteration affects androgen regulation of its host gene melanophilin .
Project description:Genome-wide association studies implicate multiple loci in risk for systemic lupus erythematosus (SLE), but few contain exonic variants, rendering systematic identification of non-coding variants essential to decoding SLE genetics. We utilized SNP-seq and bioinformatic enrichment to interrogate 2180 single-nucleotide polymorphisms (SNPs) from 87 SLE risk loci for potential binding of transcription factors and related proteins from B cells. 52 SNPs that passed initial screening were tested by electrophoretic mobility shift (EMSA) and luciferase reporter assays. To identify binding of transcription factors and/or other nuclear proteins in an allele-determined manner, we employed pulldown using nuclear extract from Daudi cells and silver staining in SNPs that had exhibited allele-specific differential binding by EMSA. Each pulldown product for each allele of the five high-probability SNPs (rs2297550 C/G, rs13213604 C/G, rs276461 T/C, rs9907955 C/T, rs7302634 T/C) was evaluated by mass spectrometry (MS) to identify binding nuclear proteins, yielding a set of candidate proteins for each.
Project description:Genome-wide association studies (GWAS) have identified dozens of genomic loci, whose single nucleotide polymorphisms (SNPs) predispose to prostate cancer (PCa). However, the biological functions of these common genetic variants and the mechanisms to increase disease risk are largely unknown. We integrated chromatin-IP coupled sequencing (ChIP-seq) and microarray expression profiling in the TMPRSS2-ERG gene rearrangement positive DuCaP cell model with the NHGRI GWAS PCa risk SNPs catalog, in an attempt to identify disease susceptibility SNPs localized within functional androgen receptor binding sites (ARBSs). Among the 48 GWAS index SNPs and 2,702 linked SNPs defined by the 1000G project 104 were found to be localized in the AR ChIP-seq peaks. Of these risk SNPs, rs11891426 T/G in the 7th intron of its host gene melanophilin (MLPH) was found located within a putative auxiliary ARE motif, which we found enriched in the neighborhood of canonical ARE motifs. Exchange of T to G attenuated the transcriptional activity of the MLPH-ARBS in a reporter gene assay. The expression of MLPH protein in tissue samples from prostate cancer patients was significantly lower in those with the G compared to the T allele. Moreover, a significant positive correlation of AR and MLPH protein expression levels was also confirmed in tissue samples. These results unravel a hidden link between AR and a functional PCa risk SNP rs11891426, whose allele alteration affects androgen regulation of its host gene MLPH. This study shows the power of integrative studies to pin down functional risk SNPs and justifies further investigations.
Project description:Mechanisms by which non-coding genetic variation influences gene expression remain only partially understood but are considered to be major determinants of phenotypic diversity and disease risk. To investigate these mechanisms with respect to signal-dependent gene expression, we evaluated effects of > 50 million SNPs and InDels provided by five inbred strains of mice on the responses of macrophages to the anti-inflammatory cytokine IL-4. Remarkably, of the > 600 genes observed to be induced >2-fold across the five strains after 24 hours of IL-4 treatment, only 26 genes reached this threshold in all strains and more than half of the induced genes were observed in only a single strain. By examining the effects of SNPs and InDels on transcription factor binding and enhancer activity under basal and IL-4 treatment conditions, we identified dominant collaborative roles of the signal-dependent transcription factors (SDTFs) STAT6, PPARg and EGR2 in driving late enhancer activation that were dependent on general macrophage lineage determining factors (LDTFs). As expected, SNPs and InDels that affected the relative affinities of SDTFs primarily influenced the ability of enhancers with similar basal activities to respond to IL-4. In contrast, SNPs and InDels that altered the relative binding affinities of macrophage LDTFs had divergent effects on basal and activated enhancer activity. Variants resulting in strong reductions in LDTF binding affinity were associated with low basal enhancer activity and failure to recruit SDTFs, whereas variants that increased LDTF binding affinities were associated with constitutively high levels of enhancer activity and a blunted response to SDTF recruitment. Together, these studies reveal mechanisms by which noncoding genetic variation influences absolute levels of enhancer activity and their dynamic responses to IL-4, thereby contributing to strain-specific patterns of gene expression and phenotypic diversity.