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:Long non-coding RNAs (ncRNAs) are major regulators of gene expression and cell fate. The INK4 locus encodes the tumour suppressor proteins p15INK4b, p16INK4a and p14ARF required for cell cycle arrest and whose expression increases during senescence. ANRIL is a ncRNA antisense to the p15 gene. In proliferative cells, ANRIL prevents senescence by repressing INK4 genes through the recruitment of Polycomb-group proteins. In models of replicative and RASval12 oncogene-induced senescence (OIS), the expression of ANRIL and Polycomb proteins decreases, thus allowing INK4 derepression. Here, we found in a model of RAF1 OIS that ANRIL expression rather increases, due in particular to an increased stability. This led us to search for circular ANRIL isoforms, as circular RNAs are rather stable species. We found that the expression of two circular ANRIL increases in several OIS models (RAF1, MEK1 and BRAF). In proliferative cells, they repress p15 expression, while in RAF1 OIS, they promote full induction of p15, p16 and p14ARF expression. Further analysis of one of these circular ANRIL shows that it interacts with Polycomb proteins and decreases EZH2 Polycomb protein localization and H3K27me3 at the p15 and p16 promoters, respectively. We propose that changes in the ratio between Polycomb proteins and circular ANRIL isoforms allow these isoforms to switch from repressors of p15 gene to activators of all INK4 genes in RAF1 OIS. Our data reveal that regulation of ANRIL expression depends on the senescence inducer and underline the importance of circular ANRIL in the regulation of INK4 gene expression and senescence.
Project description:Serine/arginine-rich splicing factor 3 (SRSF3) functions to regulate mRNA alternative splicing, a molecular mechanism to process more than 90% of the protein-coding genes and provides an essential source for the biological versatility and targeting of SRSF3 could be a novel approach for cancer therapy. This study identify that SRSF3 expression was upregulated in pancreatic cancer tissues and associated with drug resistance and poor prognosis. Thus, we found that SRSF3 regulated ANRIL splicing and modified m6A modification of ANRIL in pancreatic cancer cells. More importantly, we demonstrated that the m6A methylation on lncRNA-ANRIL was essential for splicing process. Meanwhile, we also found that the different isoforms of ANRIL were differentially expressed in drug-resistant pancreatic cancer cell lines, and SRSF3 promotes gemcitabine resistance by regulating the expression of ANRIL-208. In addition, ANRIL-208 regulated pancreatic cancer cell chemoresistance by forming a complex with Ring1b and EZH2 and enhanced DNA homologous recombination repair (HR) capacity. In conclusion, the current study first established the link among SRSF3, m6A modification, lncRNA splicing, and DNA HR repair in pancreatic cancer, and first demonstrated that abnormal alternative splicing and m6A modification are closely related to chemotherapy resistance in pancreatic cancer.
Project description:Serine/arginine-rich splicing factor 3 (SRSF3) functions to regulate mRNA alternative splicing, a molecular mechanism to process more than 90% of the protein-coding genes and provides an essential source for the biological versatility and targeting of SRSF3 could be a novel approach for cancer therapy. This study identify that SRSF3 expression was upregulated in pancreatic cancer tissues and associated with drug resistance and poor prognosis. Thus, we found that SRSF3 regulated ANRIL splicing and modified m6A modification of ANRIL in pancreatic cancer cells. More importantly, we demonstrated that the m6A methylation on lncRNA-ANRIL was essential for splicing process. Meanwhile, we also found that the different isoforms of ANRIL were differentially expressed in drug-resistant pancreatic cancer cell lines, and SRSF3 promotes gemcitabine resistance by regulating the expression of ANRIL-208. In addition, ANRIL-208 regulated pancreatic cancer cell chemoresistance by forming a complex with Ring1b and EZH2 and enhanced DNA homologous recombination repair (HR) capacity. In conclusion, the current study first established the link among SRSF3, m6A modification, lncRNA splicing, and DNA HR repair in pancreatic cancer, and first demonstrated that abnormal alternative splicing and m6A modification are closely related to chemotherapy resistance in pancreatic cancer.
Project description:Many studies have demonstrated the importance of circRNA in regulating gene expression through functioning as microRNA sponges. However, the roles of circRNA-protein interaction are not fully understood. Importantly, how circRNA-protein interaction contributes the progression of pancreatic ductal adenocarcinoma is largely unexplored. Therefore, RNA Pull down assay for investigating RNA-protein interaction was performed in PANC-1 cells.
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).
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:Long non-coding RNAs(LncRNAs)have important cellular functions and some have roles in different mechanisms of gene regulation. LncRNA-antisense noncoding RNA in the INK4 locus (ANRIL) were found to affect cell inflammation,Nevertheless, the potential genes related to the inflammatory response regulated by ANRIL remain unclear. In this study, we investigated the potential function of ANRIL in regulating expression and alternative splicing. ANRIL-regulated human umbilical vein endothelial (HUVEC) cell transcriptome achieved by high-throughput RNA sequencing(RNA-seq) was obtained to investigate the potential role of ANRIL. Lipofectamine 2000 was used for plasmid transfection. The gene expression profile and alternative splicing pattern of HUVEC overexpressed by ANRIL were analyzed by RNA-seq and compared with the control group. ANRIL overexpression (ANRIL-OE) widely affects the transcription levels of genes related to inflammatory response, NF-κB pathway, type I interferon-mediated signal transduction pathway, and innate immune response. ANRIL extensively regulates the alternative splicing of hundreds of genes through functions such as gene expression, translation, DNA repair, RNA processing, and NF-κB pathway. Many of these genes have an indispensable role in the inflammatory response. ANRIL regulated inflammatory response may be achieved by regulating alternating splicing and potential transcription, which broadens the understanding of ANRIL-mediated gene regulation mechanisms and clarifies the role of ANRIL in mediating inflammatory response mechanisms.
Project description:In this study, we achieved integrated transcriptomic and proteomic profiles of GK islets in a time-course fashion at different stages of T2D. Subsequent bioinformatics analysis revealed the chronological order of T2D-related molecular events during the deterioration of pancreatic islets. Our large quantitative dataset provide a valuable resource to obtain a comprehensive picture of the mechanisms responsible for islet dysfunction and to identify potential interventions to prevent beta-cell failure in human T2D.