Project description:Genome-wide association studies (GWAS) are identifying genetic predisposition to various diseases. The rs1859962 single nucleotide polymorphism (SNP) part of the 17q24.3 locus is a risk factor for prostate cancer (PCa). It defines a 130kb linkage disequilibrium (LD) block that lies in a ~2Mb gene desert area. Despite a role for the proximal SOX9 gene in PCa development, the functional biology driving the risk of this 17q24.3 risk locus is unknown. In the present study, we integrate genome-wide chromatin landscape datasets, namely epigenomes and chromatin openness from diverse cell-types to identify one PCa specific enhancer within the rs1859962 risk LD block. We reveal that this enhancer is part of a 1Mb chromatin loop with the SOX9 gene in PCa cells. The rs8072254 and rs1859961 SNPs part of this LD block map to this enhancer and impose allele-specific gene expression. The variant allele of rs1859961 directly decreases FoxA1 binding while increasing AP-1 binding compared to the reference allele. This latter is key in driving allele-specific gene expression. Together, our results demonstrate the risk associated with the PCa rs1859962 risk LD block is accounted for by multiple genetic variants mapping to a unique enhancer looping to the SOX9 oncogene. Allele-specific recruitment of the transcription factor AP-1 accounts in part for the increased enhancer activity ascribed to this PCa risk LD block. This further demonstrates that an integrative genomics approach can identify the functional biology disrupted by genetic risk-variants. Examination of histone modification H3K36me3 in the prostate cancer LNCaP cell line under DHT treatment.
Project description:Our fine-mapping of 76 non-MHC loci associated with risk for rheumatoid arthritis (RA, 11,475 cases, 15,870 controls) has recently identified rs117701653, a non-coding single nucleotide polymorphism (SNP) in the CTLA4/CD28/ICOS locus, as the variant most likely to modulate RA risk within this region, with the minor allele (C) showing disease protection compared to the major allele (A). Notably, this SNP exhibits allele-specific protein binding, further supporting its regulatory nature, including greater binding of proteins from Jurkat T cell nuclear extract to the protective allele (C) than to the risk allele (A) by electrophoretic mobility shift assay (EMSA). To identify this protein or protein complex, we applied an efficient DNA pulldown technique, flanking restriction enhanced pulldown (FREP), using nuclear extract from Jurkat T cells, bait DNA corresponding to the (C) allele of rs117701653, competitor DNA fragment, and irrelevant DNA sequence as a negative control. Mass spectrometry analysis of peptides released from FREP identified 43 proteins. Our strongest candidate was structural maintenance of chromosomes flexible hinge domain-containing protein 1 (SMCHD1), which exhibited specific binding to the (C) allele of rs117701653. We confirmed the allelic affinity of SMCHD1 using multiple orthogonal approaches, including FREP and western blotting, EMSA with anti-SMCHD1 antibodies, and CHIP-qPCR with CRISPR-modified Jurkat clones bearing different genotype at rs117701653. In this study, we identified SMCHD1, a chromatin regulator that binds allelically to the rs117701653 allele (C) associated with protection against RA risk.
Project description:Genome-wide association studies (GWAS) are identifying genetic predisposition to various diseases. The rs1859962 single nucleotide polymorphism (SNP) part of the 17q24.3 locus is a risk factor for prostate cancer (PCa). It defines a 130kb linkage disequilibrium (LD) block that lies in a ~2Mb gene desert area. Despite a role for the proximal SOX9 gene in PCa development, the functional biology driving the risk of this 17q24.3 risk locus is unknown. In the present study, we integrate genome-wide chromatin landscape datasets, namely epigenomes and chromatin openness from diverse cell-types to identify one PCa specific enhancer within the rs1859962 risk LD block. We reveal that this enhancer is part of a 1Mb chromatin loop with the SOX9 gene in PCa cells. The rs8072254 and rs1859961 SNPs part of this LD block map to this enhancer and impose allele-specific gene expression. The variant allele of rs1859961 directly decreases FoxA1 binding while increasing AP-1 binding compared to the reference allele. This latter is key in driving allele-specific gene expression. Together, our results demonstrate the risk associated with the PCa rs1859962 risk LD block is accounted for by multiple genetic variants mapping to a unique enhancer looping to the SOX9 oncogene. Allele-specific recruitment of the transcription factor AP-1 accounts in part for the increased enhancer activity ascribed to this PCa risk LD block. This further demonstrates that an integrative genomics approach can identify the functional biology disrupted by genetic risk-variants.
2012-06-03 | GSE35829 | GEO
Project description:BDNF gene’s role in schizophrenia: from risk allele to methylation implications
Project description:Genome-wide association studies (GWASs) have identified thousands of single nucleotide polymorphisms (SNPs) associated with human traits and diseases. But because the vast majority of these SNPs are located in the noncoding regions of the genome their risk promoting mechanisms are elusive. Employing a new methodology combining cistromics, epigenomics and genotype imputation we annotate the noncoding regions of the genome in breast cancer cells and systematically identify the functional nature of SNPs associated with breast cancer risk. Our results demonstrate that breast cancer risk-associated SNPs are enriched in the cistromes of FOXA1 and ESR1 and the epigenome of H3K4me1 in a cancer and cell-type-specific manner. Furthermore, the majority of these risk-associated SNPs modulate the affinity of chromatin for FOXA1 at distal regulatory elements, which results in allele-specific gene expression, exemplified by the effect of the rs4784227 SNP on the TOX3 gene found within the 16q12.1 risk locus. Examination of histone modification H3K4me2 in untreated and E2 treated cells
Project description:To date, single-nucleotide polymorphisms (SNPs) have been the most intensively investigated class of polymorphisms in genome wide associations studies (GWAS), however, other classes such as insertion-deletion or multiple nucleotide length polymorphism (MNLPs) may also confer disease risk. Multiple reports have shown that the 5p15.33 prostate cancer (PCa) risk region is a particularly strong expression quantitative trait locus (eQTL) for IRX4 transcripts. Here, we demonstrate using epigenome and genome editing that a biallelic (47bp/21bp) MNLP is the causal variant regulating IRX4 transcript levels. In LNCaP PCa cells (homozygous for the short allele), a single copy knock-in of the long allele potently alters the chromatin state, enabling de novo functional binding of the androgen receptor (AR) associated with increased chromatin accessibility, H3K27 acetylation, and ~3-fold upregulation of IRX4 expression. We further show that an MNLP is amongst the strongest candidate susceptibility variants at two additional PCa risk loci. We estimated that at least 5% of PCa risk loci could be explained by functional non-SNP causal variants, which may have broader implications for other cancers GWAS. More generally, our results underscore the importance of investigating other classes of inherited variation as causal mediators of human traits.
Project description:To date, single-nucleotide polymorphisms (SNPs) have been the most intensively investigated class of polymorphisms in genome wide associations studies (GWAS), however, other classes such as insertion-deletion or multiple nucleotide length polymorphism (MNLPs) may also confer disease risk. Multiple reports have shown that the 5p15.33 prostate cancer (PCa) risk region is a particularly strong expression quantitative trait locus (eQTL) for IRX4 transcripts. Here, we demonstrate using epigenome and genome editing that a biallelic (47bp/21bp) MNLP is the causal variant regulating IRX4 transcript levels. In LNCaP PCa cells (homozygous for the short allele), a single copy knock-in of the long allele potently alters the chromatin state, enabling de novo functional binding of the androgen receptor (AR) associated with increased chromatin accessibility, H3K27 acetylation, and ~3-fold upregulation of IRX4 expression. We further show that an MNLP is amongst the strongest candidate susceptibility variants at two additional PCa risk loci. We estimated that at least 5% of PCa risk loci could be explained by functional non-SNP causal variants, which may have broader implications for other cancers GWAS. More generally, our results underscore the importance of investigating other classes of inherited variation as causal mediators of human traits.
Project description:To understand the biological mechanism of ELL2 in multiple myeloma (MM), we show that the MM risk allele lowers ELL2 expression in CD138+ plasma cells (Pcombined=2.5×10-27; bcombined=-0.24 s.d.), but not in peripheral blood or other tissues. Consistent with this, several variants representing the MM risk allele map to regulatory genomic regions, and three yield reduced transcriptional activity in plasmocytoma cell lines. One of these (rs3777189-C) co-locates with the best-supported lead variants for ELL2 expression and MM risk, and reduces binding of MAFF/G/K family transcription factors. Moreover, further analysis reveals that the MM risk allele associates with upregulation of gene sets related to ribosome biogenesis, and knockout/knockdown and rescue experiments in plasmocytoma cell lines support a cause-effect relationship.
Project description:To understand the biological mechanism of ELL2 in multiple myeloma (MM), we show that the MM risk allele lowers ELL2 expression in CD138+ plasma cells (Pcombined=2.5×10-27; bcombined=-0.24 s.d.), but not in peripheral blood or other tissues. Consistent with this, several variants representing the MM risk allele map to regulatory genomic regions, and three yield reduced transcriptional activity in plasmocytoma cell lines. One of these (rs3777189-C) co-locates with the best-supported lead variants for ELL2 expression and MM risk, and reduces binding of MAFF/G/K family transcription factors. Moreover, further analysis reveals that the MM risk allele associates with upregulation of gene sets related to ribosome biogenesis, and knockout/knockdown and rescue experiments in plasmocytoma cell lines support a cause-effect relationship.