Project description:9p21 locus polymorphisms have the strongest correlation with coronary artery disease, but as a non-coding locus, disease connection is enigmatic. The lncRNA ANRIL found in 9p21 may regulate vascular smooth muscle cell (VSMC) phenotype to contribute to disease risk. We observed significant variability in induced pluripotent stem cell-derived VSMCs from patients homozygous for risk versus isogenic knockout or non-risk haplotypes. Sub-populations of risk haplotype cells exhibited variable morphology, proliferation, contraction, and adhesion. When sorted by adhesion, risk VSMCs parsed into synthetic and contractile sub-populations, i.e., weakly adherent and strongly adherent, respectively. >90% of differentially expressed genes co-regulated by haplotype and adhesion were associated with Rho GTPases, i.e., contractility. Weakly adherent sub-populations expressed more short isoforms of ANRIL, and when overexpressed in knockout cells, ANRIL suppressed adhesion, contractility, and αSMA expression. These data are the first to suggest that variable lncRNA penetrance may drive mixed functional outcomes that confound pathology.
Project description:We explored regulatory mechanism of a SNP on chromosome 9p21 associated with endometriosis by leveraging “allele-specific” functional genomic approaches. By re-sequencing 1.29 Mb of 9p21 region and scrutinizing DNase-seq data from the ENCODE project, we prioritized rs17761446 as a candidate functional variant that was in perfect linkage disequilibrium with the original GWAS SNP (rs10965235) and located on DNase I hypersensitive site. Chromosome conformation capture followed by high-throughput sequencing revealed that the protective G allele of rs17761446 exerted stronger chromatin interaction with ANRIL promoter. We demonstrated that the protective allele exhibited preferential binding affinities to TCF7L2 and EP300 by bioinformatics and chromatin immunoprecipitation (ChIP) analyses. ChIP assays for histone H3 lysine 27 acetylation and RNA polymerase II reinforced the enhancer activity of the SNP site. The allele specific expression analysis for eutopic endometrial tissues and endometrial carcinoma cell lines showed that rs17761446 was a cis-regulatory variant where G allele was associated with increased ANRIL expression.
Project description:The antisense non-coding RNA in the INK locus (ANRIL), which originates from the CDKN2A/B (INK4-ARF) locus, has been identified as a hotspot for genetic variants associated with cardiometabolic disease including coronary artery disease (CAD) and Type 2 diabetes (T2D). We recently found that ANRIL abundance in human pancreatic islets was increased in donors carrying certain T2D risk-SNPs, and that a T2D risk-SNP located within exon2 of ANRIL conferred reduced beta cell proliferation index, pointing to a role for ANRIL in the regulation of T2D pathogenicity via an impact on insulin secretory capacity. Recent studies in other cell types have found that the balance between linear and circular species of ANRIL is linked to the regulation of cardiovascular disease phenotypes. Less is known about circular ANRIL expression in diabetes-relevant cell types and how their abundance might influence the risk of T2D. Herein, we use high-throughput and divergent primer sequencing of circular RNA in human pancreatic islet cells to quantify and characterize circular isoforms of ANRIL. We identified several circular ANRIL isoforms that are more abundant than linear ANRIL and whose expression was correlated across dozens of individuals. Back-splicing did not occur with equal probability at all ANRIL splice sites. Rather, some specific splice sites were found to have a higher propensity to be involved in back-splicing and are weakly enriched for sequence features known to promote back-splicing. Finally, we found that islets from carriers of the T2D risk allele at rs564398 in exon 2 of ANRIL had a higher ratio of circular ANRIL relative to linear ANRIL compared to protective-allele carriers, and that higher circular:linear ANRIL ratio was associated with a decreased beta cell proliferation index. Together, our study points to the combined involvement of both linear and circular ANRIL species in T2D phenotypes and opens the door for future studies to understand the molecular mechanisms by which ANRIL impacts cellular function in human pancreatic islets.
Project description:The 9p21 locus encodes tumor suppressors p16INK4A and p14ARF (both encoded by CDKN2A), p15INK4B (CDKN2B), and a long non-coding RNA, ANRIL (CDKN2B-AS1). The ~1 megabase locus is notable for a high density of single nucleotide polymorphisms (SNPs) associated with aging-related diseases and traits. Despite clear importance, our understanding of the the cell-type specific expression dynamics and cis-regulatory mechanisms of the 9p21 transcripts has been constrained by the complexity of the transcript structures, low expression, and severe alterations to the locus in cancer cell lines. Here, we innovated custom computational and molecular tools to overcome these technical challenges and fill critical knowledge gaps in our understanding of 9p21 locus architecture and regulation of the 9p21 transcripts. Across tissues, we found that p15INK4b is the predominant transcript. We deconvolved the expression of the CDKN2A transcripts, p16INK4A and p14ARF, revealing stark differences in the expression of these overlapping but functionally distinct transcripts across tissues and cell types. Comparative analysis in a model of fibroblast senescence revealed a striking switch from preferential p14ARF expression in cycling cells, to p16INK4A and p15INK4b as cells age and senescence. Perturbation of putative cis regulatory elements nominated a network of promoters and enhancers that regulate p16INK4A, p14ARF, and p15INK4b and ANRIL. The identified elements are accessible in vivo, and can be used to guide studies into variant interpretation. Our systematic characterization of 9p21 transcript isoforms, promoters, and distal elements across cell states, in vivo tissues and senescence offers new mechanistic insights and a framework for future studies of this vital but poorly understood locus.
Project description:The 9p21 locus encodes tumor suppressors p16INK4A and p14ARF (both encoded by CDKN2A), p15INK4B (CDKN2B), and a long non-coding RNA, ANRIL (CDKN2B-AS1). The ~1 megabase locus is notable for a high density of single nucleotide polymorphisms (SNPs) associated with aging-related diseases and traits. Despite clear importance, our understanding of the the cell-type specific expression dynamics and cis-regulatory mechanisms of the 9p21 transcripts has been constrained by the complexity of the transcript structures, low expression, and severe alterations to the locus in cancer cell lines. Here, we innovated custom computational and molecular tools to overcome these technical challenges and fill critical knowledge gaps in our understanding of 9p21 locus architecture and regulation of the 9p21 transcripts. Across tissues, we found that p15INK4b is the predominant transcript. We deconvolved the expression of the CDKN2A transcripts, p16INK4A and p14ARF, revealing stark differences in the expression of these overlapping but functionally distinct transcripts across tissues and cell types. Comparative analysis in a model of fibroblast senescence revealed a striking switch from preferential p14ARF expression in cycling cells, to p16INK4A and p15INK4b as cells age and senescence. Perturbation of putative cis regulatory elements nominated a network of promoters and enhancers that regulate p16INK4A, p14ARF, and p15INK4b and ANRIL. The identified elements are accessible in vivo, and can be used to guide studies into variant interpretation. Our systematic characterization of 9p21 transcript isoforms, promoters, and distal elements across cell states, in vivo tissues and senescence offers new mechanistic insights and a framework for future studies of this vital but poorly understood locus.
Project description:The 9p21 locus encodes tumor suppressors p16INK4A and p14ARF (both encoded by CDKN2A), p15INK4B (CDKN2B), and a long non-coding RNA, ANRIL (CDKN2B-AS1). The ~1 megabase locus is notable for a high density of single nucleotide polymorphisms (SNPs) associated with aging-related diseases and traits. Despite clear importance, our understanding of the the cell-type specific expression dynamics and cis-regulatory mechanisms of the 9p21 transcripts has been constrained by the complexity of the transcript structures, low expression, and severe alterations to the locus in cancer cell lines. Here, we innovated custom computational and molecular tools to overcome these technical challenges and fill critical knowledge gaps in our understanding of 9p21 locus architecture and regulation of the 9p21 transcripts. Across tissues, we found that p15INK4b is the predominant transcript. We deconvolved the expression of the CDKN2A transcripts, p16INK4A and p14ARF, revealing stark differences in the expression of these overlapping but functionally distinct transcripts across tissues and cell types. Comparative analysis in a model of fibroblast senescence revealed a striking switch from preferential p14ARF expression in cycling cells, to p16INK4A and p15INK4b as cells age and senescence. Perturbation of putative cis regulatory elements nominated a network of promoters and enhancers that regulate p16INK4A, p14ARF, and p15INK4b and ANRIL. The identified elements are accessible in vivo, and can be used to guide studies into variant interpretation. Our systematic characterization of 9p21 transcript isoforms, promoters, and distal elements across cell states, in vivo tissues and senescence offers new mechanistic insights and a framework for future studies of this vital but poorly understood locus.
Project description:The 9p21 locus encodes tumor suppressors p16INK4A and p14ARF (both encoded by CDKN2A), p15INK4B (CDKN2B), and a long non-coding RNA, ANRIL (CDKN2B-AS1). The ~1 megabase locus is notable for a high density of single nucleotide polymorphisms (SNPs) associated with aging-related diseases and traits. Despite clear importance, our understanding of the the cell-type specific expression dynamics and cis-regulatory mechanisms of the 9p21 transcripts has been constrained by the complexity of the transcript structures, low expression, and severe alterations to the locus in cancer cell lines. Here, we innovated custom computational and molecular tools to overcome these technical challenges and fill critical knowledge gaps in our understanding of 9p21 locus architecture and regulation of the 9p21 transcripts. Across tissues, we found that p15INK4b is the predominant transcript. We deconvolved the expression of the CDKN2A transcripts, p16INK4A and p14ARF, revealing stark differences in the expression of these overlapping but functionally distinct transcripts across tissues and cell types. Comparative analysis in a model of fibroblast senescence revealed a striking switch from preferential p14ARF expression in cycling cells, to p16INK4A and p15INK4b as cells age and senescence. Perturbation of putative cis regulatory elements nominated a network of promoters and enhancers that regulate p16INK4A, p14ARF, and p15INK4b and ANRIL. The identified elements are accessible in vivo, and can be used to guide studies into variant interpretation. Our systematic characterization of 9p21 transcript isoforms, promoters, and distal elements across cell states, in vivo tissues and senescence offers new mechanistic insights and a framework for future studies of this vital but poorly understood locus.
Project description:The 9p21 locus encodes tumor suppressors p16INK4A and p14ARF (both encoded by CDKN2A), p15INK4B (CDKN2B), and a long non-coding RNA, ANRIL (CDKN2B-AS1). The ~1 megabase locus is notable for a high density of single nucleotide polymorphisms (SNPs) associated with aging-related diseases and traits. Despite clear importance, our understanding of the the cell-type specific expression dynamics and cis-regulatory mechanisms of the 9p21 transcripts has been constrained by the complexity of the transcript structures, low expression, and severe alterations to the locus in cancer cell lines. Here, we innovated custom computational and molecular tools to overcome these technical challenges and fill critical knowledge gaps in our understanding of 9p21 locus architecture and regulation of the 9p21 transcripts. Across tissues, we found that p15INK4b is the predominant transcript. We deconvolved the expression of the CDKN2A transcripts, p16INK4A and p14ARF, revealing stark differences in the expression of these overlapping but functionally distinct transcripts across tissues and cell types. Comparative analysis in a model of fibroblast senescence revealed a striking switch from preferential p14ARF expression in cycling cells, to p16INK4A and p15INK4b as cells age and senescence. Perturbation of putative cis regulatory elements nominated a network of promoters and enhancers that regulate p16INK4A, p14ARF, and p15INK4b and ANRIL. The identified elements are accessible in vivo, and can be used to guide studies into variant interpretation. Our systematic characterization of 9p21 transcript isoforms, promoters, and distal elements across cell states, in vivo tissues and senescence offers new mechanistic insights and a framework for future studies of this vital but poorly understood locus.
Project description:Coronary artery disease (CAD) is the most common cardiovascular disease and the leading cause of death worldwide. To date, the 9p21.3 locus is the most robust and frequently replicated risk locus of CAD among >90 CAD risk loci identified by GWAS. More than 50 CAD-associated genomic variants were identified at the 9p21.3 CAD locus and many of them are located within a long non-coding gene ANRIL, which was initially referred to as Antisense Non-coding RNA in INK4 Locus. The causal role of ANRIL in CAD and the underlying molecular mechanism are unknown. We used gene expression microarray to identify the downstream target genes of ANRIL and to explore molecular mechanisms by which ANRIL might contribute to the risk development of CAD.
Project description:Circular RNAs (circRNAs) are broadly expressed in eukaryotic cells, but their role in human health and disease remains obscure. Here, we show that circular antisense non-coding RNA in the INK4 locus (circANRIL), which is transcribed at a locus of atherosclerotic cardiovascular disease on chromosome 9p21, confers athero-protection by controlling ribosomal RNA (rRNA) maturation and modulating pathways of atherogenesis. At the molecular level, circANRIL competes with precursor rRNA (pre-rRNA) for binding to pescadillo homolog 1 (PES1), an essential 60S-preribosomal assembly factor, thereby impairing exonuclease-mediated pre-rRNA processing and ribosome biogenesis. As a consequence, circANRIL induces nucleolar stress and p53 activation, resulting in the induction of apoptosis and inhibition of proliferation, which are key athero-protective cell functions within the arterial wall. Collectively, these findings identify circANRIL as a prototype of a circRNA regulating ribosome biogenesis and conferring athero-protection, thereby unveiling a therapeutic potential of certain circRNAs in human disease. Analysis of transcriptome-wide expression level in HEK293 cells with stable overexpression of circular ANRIL (n=3) compared to a vector control (n=3).