Project description:We performed targeted long-read and short-read RNA sequencing to identify and quantify NRXN1 isoforms in human post-mortem dlPFC and hiPSC-neurons derived from controls and NRXN1+/- individuals. We also performed whole transcriptome RNA seuqencing and 10x genomics single cell sequencing to determine transcriptional changes in NRXN1+/- hiPSC-neurons compared to controls.
Project description:Tauopathies are a family of neurodegenerative diseases characterized by a shared pathology of aberrant forms of tau protein accumulation leading to neuronal death in focal areas of the brain. Positron emission tomography (PET) tracers that bind to tau aggregates are used to aid diagnosis, but there are no current therapies to eliminate these tau species. We employed targeted protein degradation technology to convert a tau PET probe into a functional degrader of pathogenic tau. The hetero-bifunctional molecule QC-01- 175 was designed to engage both tau and Cereblon (CRBN), a substrate receptor for the Cullin-4 RING E3 ubiquitin ligase family member (CRL4CRBN), to trigger tau ubiquitination and proteasomal degradation. QC-01-175 effected clearance of tau in frontotemporal dementia (FTD) patient-derived neuronal cell models, which recapitulate disease phenotypes of tau accumulation, insolubility and toxicity. Furthermore, QC-01-175 had minimal effect on tau levels in neurons from healthy controls, indicating specificity for degradation of disease-relevant forms of tau. QC-01-175 also rescued vulnerability to stress in FTD neurons, phenocopying CRISPR-mediated MAPT-knockout. This work demonstrates that aberrant tau species formed in ex vivo FTD patient-derived neurons are amenable to targeted protein degradation, representing an important advance towards the development of a tau targeted therapeutic.
Project description:MSI (Microsatellite Instability) colorectal cancer (CRC) show improved survival, are less prone to metastasis and show poor response to chemotherapy (compared to MSS tumors). The underlying reasons for these characteristics are still not understood and no specific therapeutic approach for MSI colon tumours (15% of CRC overall) has yet been developed.
The MSI process is oncogenic when it affects DNA repeat sequences that have a functional role, e.g. Small Coding Repeats (SCR). MSI also frequently affects Long Non-Coding Repeats (LNCR) in tumour DNA. In contrast to SCR, only a few LNCR are endowed with biological activity. Consequently, this area has received very little attention. Our group recently identified HSP110 mutant chaperone protein in MSI CRC that was generated by somatic deletion of a LNCR. Of interest, HSP110 mutant (due to exon skipping) have anti-oncogenic properties and the survival of MSI CRC patients receiving chemotherapy is positively associated with HSP110 mutations in tumour DNA.
The aim of the current project is to identify additional clinically relevant MSI-associated splicing aberrations due to mutations in LNCR located in splice acceptor sites. The four main steps are as follows:
1. To identify exon/intron sites affected by aberrant splicing events due to MSI in CRC . All RNASeq data will be exploited to identify recurrent splicing aberrations (mostly exon skipping) that occur specifically in MSI colon tumours;
2. To investigate for possible functional links between MSI and any detected aberrant splicing events . All specific aberrant splicing events detected by RNAseq in MSI CRC samples will be first confirmed (quantitative RT-PCR) in order to eliminate false positive cases. For validated exon candidates, the allelic profiles of adjacent intronic LNCR will be analysed (PCR and fluorescence genotyping) in CRC cell lines and primary tumours (MSI and MSS), as well as in matching normal mucosa samples in order to assess their polymorphic status;
3. To identify splicing events and LNCR mutations with clinical relevance in MSI CRC patients . All LNCR with a confirmed role in gene splicing in MSI CRC will be analysed. The clinical relevance of candidate genes will be assessed using multivariate survival regression models for Relapse- Free Survival, with interaction terms (response to chemotherapy);
4. To initiate functional studies on a limited number of clinically relevant, cancer-related genes whose splicing is perturbed in MSI cancer cells, and to develop biological tools to simplify screening in future clinical assays Similar to HSP110, we will focus on 4 or 5 mutant proteins that are promising drug therapeutic targets. Functional assays will be developed to further elucidate their role in the pathophysiology of MSI tumours. We also aim to develop biological tools for these candidate genes, such as the detection of wild-type or mutant proteins by immunohistochemistry.
Project description:We performed targeted long-read and short-read RNA sequencing to identify and quantify NRXN1 isoforms in human post-mortem dlPFC and hiPSC-neurons derived from controls and NRXN1+/- individuals.
Project description:Huntingtonâs disease (HD) is an autosomal dominant neurodegenerative disorder caused by a CAG expansion in the gene encoding Huntingtin (HTT). Transcriptome dysregulation is a major feature of HD pathogenesis, as revealed by a large body of work on gene expression profiling of tissues from human HD patients and mouse models. These studies were primarily focused on transcriptional changes affecting steady-state overall gene expression levels using microarray based approaches. A major missing component however has been the study of transcriptome changes at the post-transcriptional level, such as alternative splicing. Alternative splicing is a critical mechanism for expanding regulatory and functional diversity from a limited number of genes, and is particularly complex in the mammalian brain. Here we carried out a deep RNA-seq analysis of 7 human HD brains and 7 controls to systematically discover aberrant alternative splicing events and characterize potential associated splicing factors in HD. We identified 593 differential alternative splicing events between HD and control brains. Using an expanded panel of 54 brain tissues from patients and controls, we also identified 9 splicing factors exhibiting significantly altered expression levels in HD patient brains. Moreover, follow-up molecular analyses of one splicing factor PTBP1 revealed its impact on disease-associated splicing patterns in HD. Collectively, our data provide genomic evidence for widespread splicing dysregulation in HD brains, and suggest the role of aberrant alternative splicing in the pathogenesis of HD RNA-seq analysis of the BA4 motor cortex of 7 control and 7 Huntington's disease patients. 1.5 ug of total RNA was used for RNA-seq library preparation using the TruSeq⢠Stranded mRNA LT Sample Prep Kit (Illumina). 100x2 bp paired-end RNA-seq reads were generated on a HiSeq 2000 sequencer.
Project description:To identify aberrant splicing isoforms and potential neoantigens, we performed full-length cDNA sequencing of lung adenocarcinoma cell lines using a long-read sequencer MinION. We constructed a comprehensive catalog of aberrant splicing isoforms and detected isoform-specific peptides using proteome analysis.
Project description:Recurrent mutations in RNA splicing factors SF3B1, U2AF1, and SRSF2 have been reported in hematologic cancers including myelodysplastic syndromes (MDS) and chronic lymphocytic leukemia (CLL). However, SF3B1 is the only splicing associated gene to be found mutated in CLL and has been shown to induce aberrant splicing. To investigate if any other genomic aberration caused similar transcriptome changes, we clustered RNASeq samples based on an alternative 3’ splice site (ss) pattern previously identified in SF3B1-mutant CLL patients. Out of 215 samples, we identified 37 (17%) with alternative 3’ ss usage, the majority of which harbored known SF3B1 hotspot mutations. Interestingly, 3 patient samples carried previously unreported in-frame deletions in SF3B1 around K700, the most frequent mutation hotspot. To study the functional effects of these deletions, we used various minigenes demonstrating that recognition of canonical 3’ ss and alternative branchsite are required for aberrant splicing, as observed for SF3B1 p.K700E. The common mechanism of action of these deletions and substitutions result in similar sensitivity of primary cells towards splicing inhibitor E7107. Altogether, these data demonstrate that novel SF3B1 in-frame deletion events identified in CLL result in aberrant splicing, a common biomarker in spliceosome-mutant cancers.
Project description:Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by a CAG expansion in the gene encoding Huntingtin (HTT). Transcriptome dysregulation is a major feature of HD pathogenesis, as revealed by a large body of work on gene expression profiling of tissues from human HD patients and mouse models. These studies were primarily focused on transcriptional changes affecting steady-state overall gene expression levels using microarray based approaches. A major missing component however has been the study of transcriptome changes at the post-transcriptional level, such as alternative splicing. Alternative splicing is a critical mechanism for expanding regulatory and functional diversity from a limited number of genes, and is particularly complex in the mammalian brain. Here we carried out a deep RNA-seq analysis of 7 human HD brains and 7 controls to systematically discover aberrant alternative splicing events and characterize potential associated splicing factors in HD. We identified 593 differential alternative splicing events between HD and control brains. Using an expanded panel of 54 brain tissues from patients and controls, we also identified 9 splicing factors exhibiting significantly altered expression levels in HD patient brains. Moreover, follow-up molecular analyses of one splicing factor PTBP1 revealed its impact on disease-associated splicing patterns in HD. Collectively, our data provide genomic evidence for widespread splicing dysregulation in HD brains, and suggest the role of aberrant alternative splicing in the pathogenesis of HD