Project description:To investigate the collective role of the Dlk1-Dio3 ncRNA cluster in myogenesis, we developed two stable CRISPR-Cas9 gene-edited C2C12 skeletal muscle cell lines, Meg3-proximal cis-acting sequence (Meg3-CAS or 2-4) to over-express and Meg3-transcription start site (Meg3-TSS or 2-7) to under-express the entire mega-cluster of Dlk1-Dio3 ncRNAs. Mutations affecting the dosage of all ncRNAs expressed from the Dlk1-Dio3 locus cause profound changes in myoblast fusion and differentiation. To evaluate genome-wide perturbations in chromatin accessibility we evaluated specific histone lysine modifications, inducing the repressive histone mark, H3K27me3, and the activating mark, H3K4me3
Project description:Type 2 diabetes mellitus (T2DM) is a complex disease characterized by the inability of the insulin-producing β-cells in the endocrine pancreas to overcome insulin resistance in peripheral tissues. To determine if microRNAs are involved in the pathogenesis of human T2DM, we sequenced the small RNAs of human islets from diabetic and non-diabetic organ donors. We identified a cluster of miRNAs in an imprinted locus on human chromosome 14q32 that is highly and specifically expressed in human β-cells and dramatically down-regulated in islets from T2DM organ donors. The down-regulation of this locus strongly correlates with hyper-methylation of its promoter. Using HITS-CLIP for the essential RISC-component Argonaute, we identified disease-relevant targets of the chromosome 14q32 microRNAs, such as IAPP and TP53INP1 that cause increased β-cell apoptosis upon over-expression in human islets. Our results support a role for microRNAs and their epigenetic control by DNA methylation in the pathogenesis of T2DM. Identification of miRNA-target interaction in human islets using HITS-CLIP, one mRNA library and one miRNA library
Project description:Type 2 diabetes mellitus (T2DM) is a multi-factorial disease characterized by the inability of beta-cells in the endocrine pancreas to produce sufficient amounts of insulin to overcome insulin resistance in peripheral tissue. To investigate the function of miRNAs in T2DM, we sequenced the small RNAs of human islets cells from diabetic and non-diabetic organ donors and identified a cluster of miRNAs in an imprinted locus on human chromosome 14 to be dramatically down-regulated in T2DM islets. These miRNAs are highly and specifically expressed in human beta-cells. The down-regulation of this imprinted locus strongly correlates with increased methylation of its promoter in T2DM islets, providing evidence for an epigenetic modification that contributes to the pathogenesis of T2DM. Targets of the Chr 14q32 cluster of miRNAs were identified by high-throughput sequencing of cross-linked and immunoprecipitated RNA (HITS-CLIP) of Argonaute. We have also identified a unique class of sequences, termed chimeric reads, that represent an in vivo ligation of miRNAs and their targets while in complex with Argonaute, and which allow for the direct identification of miRNA:target relationships in vivo. There are three experiments in this submission. All are in human islets or islet cell types. The first is a comparison of miRNA levels in sorted alpha versus beta cells. There is one replicate for this experiment. The second experiment is to measure the expression of miRNAs in whole islets as a function of glucose levels. There are three levels and one replicate for each condition. The third exeriment is a comparison of whole islets taken from human donors that were suspected/confirmed Type 2 diabetic or considered controls. There are 3 controls and 4 T2D samples.
Project description:Although many long non-coding RNAs (lncRNAs) are controlled by genomic imprinting, their roles often remain unknown. The Dlk1-Dio3 imprinted domain expresses the lncRNA Meg3 (also called Gtl2) and multiple microRNAs and snoRNAs from the maternal chromosome. This locus constitutes an epigenetic model for pluripotency and development, particularly for neurogenesis. The domain’s Dlk1 (Delta-like-1) gene encodes a ligand that inhibits Notch1 signalling and regulates diverse developmental processes. Using a hybrid embryonic stem (ES) cell system, we find that Dlk1 becomes imprinted during neural differentiation and that this involves chromatin activation and transcriptional up-regulation on the paternal chromosome. On the maternal chromosome, the Dlk1 gene remains poised. This allelic protection against gene activation is controlled in cis by Meg3 expression and also involves the H3-lysine-27 methyltransferase Ezh2. Maternal Meg3 expression additionally protects against de novo DNA methylation at its promoter. Concordantly, we find that the lncRNA Meg3 is nuclear, accumulates onto the imprinted locus and overlaps in cis with Dlk1 in embryonic cells. Our data evoke an imprinting model in which a mono-allelic lncRNA prevents chromatin and gene activation in cis during development.
Project description:The imprinted Dlk1-Dio3 domain comprises the developmental genes Dlk1 and Rtl1, which are silenced on the maternal chromosome in different cell types. On this parental chromosome, the domain’s imprinting control region activates a polycistron that produces the lncRNA Meg3 and many miRNAs (Mirg) and C/D-box snoRNAs (Rian). Although Meg3 lncRNA is nuclear and associates with the maternal chromosome, it is unknown whether it controls gene repression in cis. We created mouse embryonic stem cells (mESCs) that carry an ectopic poly(A) signal, reducing RNA levels along the polycistron, and generated Rian-/- mESCs as well. Upon ESC differentiation, we found that Meg3 lncRNA (but not Rian) is required for Dlk1 repression on the maternal chromosome. Biallelic Meg3 expression acquired through CRISPR-mediated demethylation of the paternal Meg3 promoter led to biallelic Dlk1 repression, and to loss of Rtl1 expression. lncRNA expression also correlated with DNA hypomethylation and CTCF binding at the 5’-side of Meg3. Using Capture Hi-C, we found that this creates a Topologically Associating Domain (TAD) organization that brings Meg3 close to Dlk1 on the maternal chromosome. The requirement of Meg3 for gene repression and TAD structure may explain how aberrant MEG3 expression at the human DLK1-DIO3 locus associates with imprinting disorders.
Project description:Type 2 diabetes mellitus (T2DM) is a complex disease characterized by the inability of the insulin-producing β-cells in the endocrine pancreas to overcome insulin resistance in peripheral tissues. To determine if microRNAs are involved in the pathogenesis of human T2DM, we sequenced the small RNAs of human islets from diabetic and non-diabetic organ donors. We identified a cluster of miRNAs in an imprinted locus on human chromosome 14q32 that is highly and specifically expressed in human β-cells and dramatically down-regulated in islets from T2DM organ donors. The down-regulation of this locus strongly correlates with hyper-methylation of its promoter. Using HITS-CLIP for the essential RISC-component Argonaute, we identified disease-relevant targets of the chromosome 14q32 microRNAs, such as IAPP and TP53INP1 that cause increased β-cell apoptosis upon over-expression in human islets. Our results support a role for microRNAs and their epigenetic control by DNA methylation in the pathogenesis of T2DM.
Project description:We report the DNA-methylation profiling of 10 regions selected from the DLK1-DIO3 domain on chromosome 14q32 in BM/PB samples from patients with acute promyelocytic leukaemia (APL), other subclasses of acute myeloid leukaemia and healthy donors, using high-throughput amplicon bisulfite sequencing with Roche 454 technology. We identify monoallelic-hypermethylation in APL only at the differentially methylated region (DMR) located upstream from the MEG3 gene (MEG3-DMR), whereas no changes in the DNA methylation profile were detected at the imprinting control region of the domain (IG-DMR) among the samples analysed. We show that the expression profile of 6 miRNAs clustered downstream from the MEG3-DMR correlates with the methylation profile at both DMRs. We demonstrate that miRNAs expression negatively correlates with DNA-methylation at the IG-DMR and MEG3 gene-body, whereas the correlation was positive for the CpGs located in the promoter of MEG3, including the binding sites for the insulator CTCF. We propose a loss of imprinting at the CTCF binding sites in patients with APL. These results are consistent with the previously reported DLK1-DIO3 miRNAs overexpression in APL, indicating a possible involvement of these ncRNAs in the pathogenesis of the disease. Investigation of the epigenetic regulation of the miRNAs clustered in 14q32 by next-generation sequencing
Project description:Pluripotent stem cells are increasingly used for therapeutic models, including transplantation of neural progenitors derived from human embryonic stem cells (hESCs). Recently, long non-coding RNAs (lncRNAs), including Maternally Expressed Gene 3 (MEG3) that is derived from DLK1-DIO3 imprinted locus, were found to be expressed during neural developmental events. Their deregulations are associated with various neurological diseases. The DLK1-DIO3 imprinted locus encodes abundant non-coding RNAs (ncRNAs) that are regulated by differential methylation on the locus. The aim of our research is to study the correlation between the DLK1-DIO3 derived ncRNAs and the capacity of hESC neural lineage differentiation. We classified hESCs into MEG3-ON and MEG3-OFF based on the expression levels of MEG3 as well as its downstream miRNAs by qRT-PCR. Initial embryoid body (EB) formation was conducted to examine the three germ layer differentiation ability. cDNA microarray was used to analyze the gene expression profiles of hESCs. Directed neural lineage differentiation was performed, followed by analysis of neural lineage marker expression levels and neurite formation via qRT-PCR and immunocytochemistry methods to investigate the capacity of neural differentiation in MEG3-ON and MEG3-OFF hESCs To study the correlations between the DLK1-DIO3 derived ncRNAs and differentiation capacity of hESC toward neural lineage, we classified hESCs into MEG3-ON and MEG3-OFF based on the expression levels of MEG3 by qRT-PCR and validated the methylation patterns of DLK1-DIO3 locus by bisulfite-sequencing. Then we conducted transcriptome analysis of these two groups of hESCs by cDNA microarray. This set contained 12 microarray samples, including 4 MEG3-ON hESCs, 7 MEG3-OFF hESCs, and 1 embryoid body as the negative control of pluripotentcy for pluritest.
Project description:Type 2 diabetes mellitus (T2DM) is a multi-factorial disease characterized by the inability of beta-cells in the endocrine pancreas to produce sufficient amounts of insulin to overcome insulin resistance in peripheral tissue. To investigate the function of miRNAs in T2DM, we sequenced the small RNAs of human islets cells from diabetic and non-diabetic organ donors and identified a cluster of miRNAs in an imprinted locus on human chromosome 14 to be dramatically down-regulated in T2DM islets. These miRNAs are highly and specifically expressed in human beta-cells. The down-regulation of this imprinted locus strongly correlates with increased methylation of its promoter in T2DM islets, providing evidence for an epigenetic modification that contributes to the pathogenesis of T2DM. Targets of the Chr 14q32 cluster of miRNAs were identified by high-throughput sequencing of cross-linked and immunoprecipitated RNA (HITS-CLIP) of Argonaute. We have also identified a unique class of sequences, termed chimeric reads, that represent an in vivo ligation of miRNAs and their targets while in complex with Argonaute, and which allow for the direct identification of miRNA:target relationships in vivo.