Project description:<p> Human disorders of mitochondrial oxidative phosphorylation (OXPHOS) represent a devastating collection of inherited diseases. These disorders impact at least 1:5000 live births, and are characterized by multi-organ system involvement. They are characterized by remarkable locus heterogeneity, with mutations in the mtDNA as well as in over 77 nuclear genes identified to date. It is estimated that additional genes may be mutated in these disorders. </p> <p>To discover the genetic causes of mitochondrial OXPHOS diseases, we performed targeted, deep sequencing of the entire mitochondrial genome (mtDNA) and the coding exons of over 1000 nuclear genes encoding the mitochondrial proteome. We applied this 'MitoExome' sequencing to 124 unrelated patients with a wide range of OXPHOS disease presentations from the Massachusetts General Hospital Mitochondrial Disorders Clinic. </p> <p>The 2.3Mb targeted region was captured by hybrid selection and Illumina sequenced with paired 76bp reads. The total set of 1605 targeted nuclear genes included 1013 genes with strong evidence of mitochondrial localization from the MitoCarta database, 377 genes with weaker evidence of mitochondrial localization from the MitoP2 database and other sources, and 215 genes known to cause other inborn errors of metabolism. Approximately 88% of targeted bases were well-covered (>20X), with mean 200X coverage per targeted base. </p>
Project description:Long non-coding RNAs (lncRNAs) are defined as non-protein-coding transcripts that are at least 200 nucleotides long. They are known to play pivotal roles in regulating gene expression, especially during stress responses in plants. We used a large collection of in-house transcriptome data from various soybean (Glycine max and Glycine soja) tissues treated under different conditions to perform a comprehensive identification of soybean lncRNAs. We also retrieved publicly available soybean transcriptome data that were of sufficient quality and sequencing depth to enrich our analysis. In total, RNA-seq data of 332 samples were used for this analysis. An integrated reference-based, de novo transcript assembly was developed that identified ~69,000 lncRNA gene loci. We showed that lncRNAs are distinct from both protein-coding transcripts and genomic background noise in terms of length, number of exons, transposable element composition, and sequence conservation level across legume species. The tissue-specific and time-specific transcriptional responses of the lncRNA genes under some stress conditions may suggest their biological relevance. The transcription start sites of lncRNA gene loci tend to be close to their nearest protein-coding genes, and they may be transcriptionally related to the protein-coding genes, particularly for antisense and intronic lncRNAs. A previously unreported subset of small peptide-coding transcripts was identified from these lncRNA loci via tandem mass spectrometry, which paved the way for investigating their functional roles. Our results also highlight the current inadequacy of the bioinformatic definition of lncRNA, which excludes those lncRNA gene loci with small open reading frames (ORFs) from being regarded as protein-coding.
Project description:Introduction. Hindered by a limited understanding of the molecular mechanisms responsible for diabetic gastroenteropathy (DGE), patients are managed by symptom-based therapies. We investigated the duodenal mucosal expression of protein-coding genes and miRNAs in DGE and related these abnormalities to clinical features. Methods. mRNA and micro RNA (miRNA) expression and ultrastructure of duodenal mucosal biopsies were investigated in 39 DGE patients and 21 healthy controls. Results were analyzed in the context of diabetic phenotype and gastric emptying. Results. There were 3175 differentially-expressed genes (FDR<0.05), especially mitochondrial genes, in DGE versus controls. Several mitochondrial (mt) DNA-encoded genes (12 of 13 protein coding genes mainly involved in oxidative phosphorylation (OXPHOS), both rRNAs and 9 of 22 tRNAs) were downregulated; conversely, nuclear (n) DNA-encoded mitochondrial genes (eg, OXPHOS, TCA cycle) were upregulated in DGE. Motif analysis uncovered binding sites for transcription factors NRF1, GABPA and YY1, which regulate mitochondrial biogenesis, in the promoters of differentially expressed genes. Seventeen of 30 differentially expressed miRNAs in DGE targeted differentially expressed mitochondrial genes. Mitochondrial density was also reduced and correlated with the expression of 9 mt-DNA OXPHOS genes in DGE. Uncovered by a principal component (PC) analysis of OXPHOS genes, PC1 was significantly associated with neuropathy (P = 0.01) and with delayed gastric emptying (P < 0.05). Conclusion. In DGE, mtDNA- and nDNA-encoded mitochondrial genes are reduced and increased, respectively, associated with reduced mitochondrial density, neuropathy, and delayed gastric emptying, and correlated with cognate miRNA expression. Together, these findings provide substantial evidence for clinically-relevant mitochondrial disturbances in DGE.
Project description:<p> Human disorders of mitochondrial oxidative phosphorylation (OXPHOS) represent a devastating collection of inherited diseases. These disorders impact at least 1:5000 live births, and are characterized by multi-organ system involvement. They are characterized by remarkable locus heterogeneity, with mutations in the mtDNA as well as in over 77 nuclear genes identified to date. It is estimated that additional genes may be mutated in these disorders. </p> <p>To discover the genetic causes of mitochondrial OXPHOS diseases, we performed targeted, deep sequencing of the entire mitochondrial genome (mtDNA) and the coding exons of over 1000 nuclear genes encoding the mitochondrial proteome. We applied this 'MitoExome' sequencing to 124 unrelated patients with a wide range of OXPHOS disease presentations from the Massachusetts General Hospital Mitochondrial Disorders Clinic. </p> <p>The 2.3Mb targeted region was captured by hybrid selection and Illumina sequenced with paired 76bp reads. The total set of 1605 targeted nuclear genes included 1013 genes with strong evidence of mitochondrial localization from the MitoCarta database, 377 genes with weaker evidence of mitochondrial localization from the MitoP2 database and other sources, and 215 genes known to cause other inborn errors of metabolism. Approximately 88% of targeted bases were well-covered (>20X), with mean 200X coverage per targeted base. </p>
Project description:Approximately half of all microRNAs reside within intronic regions and are often co-transcribed with their host genes. However, most studies on intronic microRNAs focus on individual microRNAs, and conversely most studies on protein-coding and non-coding genes frequently ignore any intron-derived microRNAs. We hypothesize that the individual components of such multi-genic loci may play cooperative or competing roles in driving disease progression, and that examining the combinatorial effect of these components would uncover deeper insights into their functional importance. To address this, we perform systematic analyses of intronic microRNA:host loci in colon cancer. We observe that the FTX locus, comprising of a long non-coding RNA FTX and multiple intronic microRNAs, is highly upregulated in cancer and demonstrate that cooperativity within this multi-component locus promotes cancer growth. In addition, we show that FTX interacts with DHX9 and DICER and delineate its novel roles in regulating A-to-I RNA editing and microRNA expression. These results show for the first time that a long non-coding RNA can regulate A-to-I RNA editing, further expanding the functional repertoire of long non-coding RNAs. We further demonstrate the inhibitory effects of intronic miR-374b and -545 on the tumor suppressors PTEN and RIG-I to enhance the proto-oncogenic PI3K-AKT signaling. Finally, we show that intronic miR-421 may exert an autoregulatory effect on miR-374b and -545. Taken together, our data unveil the intricate interplay between intronic microRNAs and their host transcripts in the modulation of key signaling pathways and disease progression, adding new perspectives to the functional landscape of multi-genic loci.
Project description:Background & Aims: The contribution of genetics to the pathogenesis of inflammatory bowel disease (IBD) has been established by twin studies, targeted sequencing and genome-wide association studies (GWASs). This has yielded a plethora of risk loci with an aim to identify causal variants. Research on the genetic components of IBD has mainly focused on protein coding genes, thereby omitting other functional elements in the human genome i.e. the regulatory regions. Methods: Using acetylated histone 3 lysine 27 (H3K27ac) chromatin immunoprecipitation and sequencing (ChIP-seq), we identified tens of thousands of potential regulatory regions that are active in intestinal epithelium and immune cells, the main cell types involved in IBD. We correlated these regions with susceptibility loci for IBD. Results: We show that 45 out of 163 single nucleotide polymorphisms (SNPs) associated with IBD co-localize with active regulatory elements. In addition, another 47 IBD associated SNPs co-localize with active regulatory element via other SNP in strong linkage disequilibrium. Altogether 92 out of 163 IBD-associated SNPs can be connected with distinct regulatory element. This is 2.5 to 3.5 times more frequent than expected from random sampling. The genomic variation in these SNPs often creates or disrupts known binding motifs - thereby possibly affecting the binding affinity of transcriptional regulators and altering the expression of regulated genes. Conclusions: We show that in addition to protein coding genes, non-coding DNA regulatory regions, active in immune cells and in intestinal epithelium, are involved in IBD. H3K27ac ChIP-seq (ab4729, Abcam) profile of 7 intestinal epithelial samples
Project description:Genome-wide association studies have identified over 70 common variants that are associated with breast cancer risk. Most of these variants map to non-protein-coding regions; several map to gene deserts, regions of several hundred kb lacking protein-coding genes. We hypothesized that gene deserts harbour long-range regulatory elements that can physically interact with target genes to influence their expression. To test this, we developed Capture Hi-C (CHi-C), which by incorporating a sequence capture step into a Hi-C protocol, allows high-resolution analysis of targeted regions of the genome. We used CHi-C to investigate long-range interactions at three breast cancer gene deserts mapping to 2q35, 8q24.21 and 9q31.2. We identified interaction peaks between putative regulatory elements ("bait fragments") within the captured regions and "targets" that included both protein-coding genes and long non-coding (lnc)RNAs, over distances of 6.6 kb to 2.6 Mb. Target protein-coding genes were IGFBP5, KLF4, NSMCE2 and MYC; target lncRNAs included DIRC3, PVT1 and CCDC26. For two gene deserts we were able to define a set of SNPs that were correlated with the published risk variant and that clustered within the bait end of an interaction peak. Preliminary functional analyses implicate one SNP (rs12613955; 2q35) as a potentially functional variant. Capture Hi-C was carried out in BT483, SUM44, and GM06990 cell lines to investigate breast cancer risk loci 2q35, 8q24.21 and 9q31.2.
Project description:The CRISPR-Cas9 system enables efficient sequence-specific mutagenesis for creating germline mutants of model organisms. Key constraints in vivo remain the expression and delivery of active Cas9-guideRNA ribonucleoprotein complexes (RNPs) with minimal toxicity, variable mutagenesis efficiencies depending on targeting sequence, and high mutation mosaicism. Here, we established in vitro-assembled, fluorescent Cas9-sgRNA RNPs in stabilizing salt solution to achieve maximal mutagenesis efficiency in zebrafish embryos. Sequence analysis of targeted loci in individual embryos reveals highly efficient bi-allelic mutagenesis that reaches saturation at several tested gene loci. Such virtually complete mutagenesis reveals preliminary loss-of-function phenotypes for candidate genes in somatic mutant embryos for subsequent generation of stable germline mutants. We further show efficient targeting of functional non-coding elements in gene-regulatory regions using saturating mutagenesis towards uncovering functional control elements in transgenic reporters and endogenous genes. Our results suggest that in vitro assembled, fluorescent Cas9-sgRNA RNPs provide a rapid reverse-genetics tool for direct and scalable loss-of-function studies beyond zebrafish applications.