Project description:TDP-43 is an important RNA binding protein. To better understand its binding targets in human neurons, we performed TDP-43 iCLIP on SHSY5Y cells.
Project description:A stable HEK293 FlpIn T-Rex cells expressing TDP-43 with an N-terminal eGFP-tag was generated that allowed inducible physiological expression of the protein (Ling et al. 2010). Duplicate iCLIP experiments were performed using an antibody targeting eGFP (Abcam ab290). Crosslinked RNA-protein complexes were isolated by immuno-precipitation and cDNAs were generated to allow preparation of Illumina compatible DNA libraries as described in Huppertz et al. (2014).
Project description:QuantSeq-Rev method to generate highly strand-specific next-generation sequencing (NGS) libraries enabling transcript quantification and identification of the 3'end of polyadenylated RNAs
Project description:To investigate how translation changed as a function of TDP-43 CR loss, mass spectrometry (MS) based approach was performed to monitor the dynamics of TDP-43-associated protein complexes in response to CR deletion using TDP-43 knockout HEK293 cells expressing strep tagged wild type TDP-43 (TDP-43WT) or TDP-43ΔCR mutant.
Project description:In recent times, high throughput screening analyses have broadly defined the RNA cellular targets of TDP-43, a nuclear factor involved in neurodegeneration. A common outcome of all these studies is that changing the expression levels of this protein can alter the expression of several hundred RNAs within cells. What still remains to be clarified is which changes represent direct cellular targets of TDP-43 or just secondary variations due to the general role played by this protein in RNA metabolism. Using a HTS-based splicing junction analysis we have now identified 162 splicing events that are consistent with being directly controlled by TDP-43. Validation of the data, both in neuronal and non-neuronal cell lines demonstrated that TDP-43 substantially alters the levels of isoform expression in four genes potentially important for neuropathology: MADD/IG20, STAG2, FNIP1, and BRD8. Most importantly, for MADD/IG20 and STAG2 these changes could also be confirmed at the protein level. These alterations were also observed in a cellular model that successfully mimics TDP-43 loss of function effects following its aggregation. These novel splicing events may represent potential biomarkers to predict disease onset, progression, and to test the efficacy of novel therapeutic agents to recover TDP-43 functional properties. We have performed an HTS-based splicing junction analysis of a series of stable cell lines that lack TDP-43, overexpress this factor, or express an RNA-binding mutant, in order to find splicing events, potentially associated with neurodegenerativce diseases, regulated by this splicing factor. Samples were analyzed in triplicate from: The following samples were analyzed in triplicate: wild-type HEK-293 cells, siTDP43-treated HEK-293 cells, siTDP43-treated HEK-293 cells overexpressing a flagged-wildtype TDP-43, siTDP43-treated HEK-293 cells overexpressing a RNA-binding deficient mutant.
Project description:LIN28 is a conserved RNA binding protein implicated in pluripotency, reprogramming and oncogenesis. Previously shown to act primarily by blocking let-7 microRNA (miRNA) biogenesis, here we elucidate distinct roles of LIN28 regulation via its direct messenger RNA (mRNA) targets. Through cross-linking and immunoprecipitation coupled with high-throughput sequencing (CLIP-seq) in human embryonic stem cells and somatic cells expressing exogenous LIN28, we have defined discrete LIN28 binding sites in a quarter of human transcripts. These sites revealed that LIN28 binds to GGAGA sequences enriched within loop structures in mRNAs, reminiscent of its interaction with let-7 miRNA precursors. Among LIN28 mRNA targets, we found evidence for LIN28 autoregulation and also direct but differing effects on the protein abundance of splicing regulators in somatic and pluripotent stem cells. Splicing-sensitive microarrays demonstrated that exogenous LIN28 expression causes widespread downstream alternative splicing changes. These findings identify important regulatory functions of LIN28 via direct mRNA interactions. In triplicate, polyA-selected RNA was extracted from untreated Flp-In-293 cells, stable LIN28V5 293 cells, TDP-43 over-expressed Flp-In-293 cells, control over-expressed Flp-In-293 cells, LIN28 depleted hES cells, and control depleted hES cells, and hybridized to custom human splicing sensitive microarrays
Project description:QuantSeq-Rev method to generate highly strand-specific next-generation sequencing (NGS) libraries enabling transcript quantification and identification of the 3'end of polyadenylated RNAs
Project description:Mutations in TDP-43 (an RNA binding protein) are known to cause amyotrophic lateral sclerosis (ALS). Previously, our group and several other studies showed that TDP-43 binds to several RNA targets in the mammalian CNS. ALS causing mutations in the C-terminal region of TDP-43 that is involved in splicing regulation may lead to aberrant splicing of several RNA transcripts. The main aim of this study is to identify the effect of an ALS causing mutation on the splicing regulation of previously known targets of TDP-43. Mice overexpressing a mutant human TDP-43 (hTDP-43) gene were obtained from The Jackson Laboratory (strain name - B6;CB-Tg(Prnp-TARDBP*A315T) 95Balo/J; Stock no:010700). Mutant hTDP43 was expressed under the control of a prion protein promoter that drives the expression mainly in the mouse CNS and the male transgenic mice developed symptoms around 12 weeks of age while the female mice develop symptoms approximately 20 weeks of age. Therefore, Tg animals that are 50 days old were considered pre-symptomatic and 100 days old (Tg) animals were considered to be in the post-symptomatic stages of the disease for exon array experiments. Age and sex matched pre and post-symptomatic transgenic animals and their wild type littermates were euthanised by cervical dislocation and tissues (brain and spinal cord) were harvested immediately for total RNA isolation experiments (n=3 per group). 200 ng of total RNA from transgenic TDP-43 mice and wild type animals was converted to cDNA and then amplified using the Applause WT-Amp Plus ST kit (NuGEN). Amplified cDNA was then fragmented and biotin labeled using the Encore Biotin Module kit (NuGEN) according to the manufacturer's instruction manual. Labelled cDNA was then hybridised onto Affymetrix GeneChip Exon 1.0 ST arrays in a hybridisation oven at 45 degrees C for 20 hours at 60rpm. After hybridization, washing and staining of the arrays were carried out using Affymetrix fluidics station 450 followed by scanning using GeneChip scanner. GeneChip Command Console Software (AGCC) controlled both the fluidics station and the scanner. CEL files generated by AGCC were uploaded onto Partek software and the data analysis was carried out using the exon array analysis workflow. Exon 1.0 ST arrays contain many more probes, which are classified into three major types based on their source. They are Core, extended and full probe set annotation. Core annotation refers the probe sets that are the most reliable of the three and is derived based on evidences from Refseq and GenBank. Extended annotations refer to probe sets that are generated based on EST sequences, ENSEMBL gene collections and other databases including those used for generating core probe sets. The full annotation refers to probe sets that are purely based on computational predictions. Core probe set annotation, unlike the extended or full annotation excludes the speculative probes reducing the incidence of false positives and was employed for exon array analysis. Alt-splice Anova, a statistical tool available in Partek was used for identifying novel alternative splicing events.