Project description:Nonsense-mediated mRNA decay (NMD) functions to degrade transcripts bearing premature stop codon (PTC) and is a crucial regulator of gene expression. NMD and the UPF3B gene have been implicated as the cause of various forms of intellectual disability (ID) and other neurological symptoms. Here, we reports three patients with global developmental delay carrying hemizygous deletions of the UPF2 gene, another important member of the NMD pathway and direct interacting partner of UPF3B. Using RNA-SEQ on lymphoblastoid cells from UPF2 deletion patients, we identified 1009 differently expressed genes (DEGs). 38% of these DEGs overlapped with DEGs identified in UPF3B patients. More importantly, 95% of all DEGs in either UPF2 or UPF3B patients share the same trend of de-regulation. This demonstrates that the transcriptome deregulation in these two patient groups is similar and that UPF2 should be considered as a new candidate gene for ID in man. We expanded our inq`uiries and performed a comprehensive search for copy number variations (CNVs) encompassing all NMD genes in cohorts of ID patients and controls. We found that UPF2, UPF3A, Y14, SMG6 and EIF4A3 are frequently deleted and/or duplicated in ID patients. These CNVs are likely to be the root of the problems or to act as predisposing factors. Our results suggest that dosage imbalance of NMD factors is associated with ID and further emphasize the importance of NMD in normal learning and memory processes.
Project description:Nonsense-mediated mRNA decay (NMD) surveillance pathways are best known to be involved in the degradation of mRNA with premature termination codons (PTCs). More recent studies demonstrate that the role of NMD pathways goes well beyond the degradation of PTC containing mRNA, into the regulation of cell function and thus normal development. We have taken advantage of the availability of naturally occurring loss of function mutations in the UPF3B gene, a major component of the exon junction complex (EJC), to inquire about genome-wide consequences of compromised NMD. We identify that about 5% of the lymphoblastoid cell transcriptome is directly or indirectly impacted upon in patients with UPF3B mutations with minimal effect on alternative splicing. We identify UPF3A-NMD as a likely, major modifier of the UPF3B patient phenotype through variable UPF3A protein stabilisation. Among the most consistently deregulated direct targets of UPF3B-NMD we identify the ARHGAP24 as the most likely gene implicated in the neuronal phenotype of UPF3B patients. To assess the impact of UPF3B-NMD deficiency on human transcriptome, we sequenced polyA RNA extracted from lymphoblastoid cell lines of patients (n=4) and controls (n=2). We complemented the analysis using Affymetrix Human Exon 1.0 St array using total RNA of the same cell line from patients (n=5, 3 of whom were also sequenced) and controls (n=5). Moreover, we overlapped identified differently expressed genes with copy number variation data of the patients, obtained using Illumina Human Omniexpress chip, to exclude possible false positive. Supplementary file: A splice junction reference file generated for alignment of junction reads. Alignment files linked to individual Sample records.
Project description:Proteasomes are large multi-subunit enzymes that act as the main producers of antigenic peptides presented at the cell surface to CD8+ T cells. They can simply cut proteins or recombine their fragments thereby generating novel sequences, i.e. spliced peptides via a process called proteasome-catalysed peptide splicing (PCPS). In order to gain more insight into these processes, we here perform in vitro digestions of 55 synthetic polypeptide substrates by proteasome isoforms followed by LC-MS/MS measurements using different Mass Spectrometers.
Project description:The human genome shares a remarkable amount of genomic sequence with our closest living primate relatives. Researchers have long sought to understand what regions of the genome are responsible for unique species-specific traits. Previous studies have shown that many genes are differentially expressed between species, but the regulatory elements contributing to these differences are largely unknown. Here we report a genome-wide comparison of active gene regulatory elements in human, chimpanzee, and macaque, and we identify hundreds of regulatory elements that have been gained or lost in the human or chimpanzee genomes since their evolutionary divergence. These elements contain evidence of natural selection and correlate with species-specific changes in gene expression. Polymorphic DNA bases in transcription factor motifs that we found in these regulatory elements may be responsible for the varied biological functions across species. This study directly links phenotypic and transcriptional differences between species with changes in chromatin structure. One biological replicate was analyzed for each of the 15 primate samples using DNase-seq.
Project description:The human genome shares a remarkable amount of genomic sequence with our closest living primate relatives. Researchers have long sought to understand what regions of the genome are responsible for unique species-specific traits. Previous studies have shown that many genes are differentially expressed between species, but the regulatory elements contributing to these differences are largely unknown. Here we report a genome-wide comparison of active gene regulatory elements in human, chimpanzee, and macaque, and we identify hundreds of regulatory elements that have been gained or lost in the human or chimpanzee genomes since their evolutionary divergence. These elements contain evidence of natural selection and correlate with species-specific changes in gene expression. Polymorphic DNA bases in transcription factor motifs that we found in these regulatory elements may be responsible for the varied biological functions across species. This study directly links phenotypic and transcriptional differences between species with changes in chromatin structure. DGE-seq
Project description:HERC2 is a giant protein with E3 ubiquitin ligase activity and other known and suspected functions. Mutations of HERC2 are implicated in the pathogenesis of various cancers and result in various severe neurological conditions in Herc2-mutant mice. Recently, a pleotropic autosomal recessive HERC2-associated syndrome of intellectual disability, autism and variable neurological deficits was described; its pathogenetic basis is largely unknown. Using peripheral blood-derived lymphoblasts from 3 persons with homozygous HERC2 variants and 14 age- and gender-matched controls, we performed unbiased HPLC-tandem mass spectrometry-based proteomic analyses to provide insights into HERC2-mediated pathobiology. We found that out of 3427 detected proteins, there were 812 differentially expressed proteins between HERC2-cases vs. controls. 184 canonical pathways were enriched after FDR adjustment, including mitochondrial function, energy metabolism, EIF2 signaling, immune functions, ubiquitination and DNA repair. Ingenuity Pathway Analysis® identified 209 upstream regulators that could drive the differential expression, prominent amongst which were neurodegeneration-associated proteins. Differentially expressed protein interaction networks highlighted themes of immune function/dysfunction, regulation of cell cycle/cell death, and energy metabolism. Overall, the analysis of the HERC2-associated proteome revealed striking differential protein expression between cases and controls. The large number of differentially expressed proteins likely reflects HERC2’s multiple domains and numerous interacting proteins. Our canonical pathway and protein interaction network findings suggest derangements of multiple pathways in HERC2-associated disease.
Project description:Metaphase chromosome staining was used to provide a high level overview of the pattern of histone modifications (H3K27ac, H3K27me3 and H3K4me3) at a single cell level in human lymphoblastois cells. These epigenomic banding patterns were related to various genomic features including gene and CpG island density as well as gene expression. A 3 array study using RNA extracted from 3 separate cultures of human lymphoblastoid cells as biological replicates
Project description:Histone deacetylase inhibitors are a class of drug which rapidly induce hyperacetylation of histone proteins. Here, we aimed to study the association between HDACi-induced histone acetylation and changes in gene expression. To study the early responses to HDACi treatment we treated cells with three different concentrations of two HDACi, sodium valproate (VPA) and suberoylanilide hydroxamic acid over a short timecourse. AH LCL cells were treated with 0.2mM, 1mM or 5mM valproic acid (VPA) or 0.5, 2.5 or 12.5µM suberoylanilide hydroxamic acid (SAHA). GM12878 cells were treated with 1mM VPA. Samples were collected at 0, 30, 60 and 120 minutes. All experiments were carried out in triplicate. One replicate of AH LCL, 0.2mM VPA, 30min and one replicate of AH LCL, 5mM VPA, 30min were eliminated as outliers
Project description:Adult polyglucosan body disease is a rare autosomal recessive neurologicla disorder with progressive paralysis, sensory deficits, and neurogenic bladder usually manifesting late in life. The disease is derived from glycogen branching enzyme deficiency that leads to aggregation of polyglucosan bodies in many cell types. This project focuses on delinating disease mechanisms in APBD through studying the proteomes of lymphoblasts of 3 patients with APBD and comparing them to several controls.