TDP-43 aggregation induced by oxidative stress causes global mitochondrial imbalance in ALS
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PROVIDER: PRJNA523364 | ENA |
REPOSITORIES: ENA
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Project description:When mutant superoxide dismutase 1 (SOD1) was first linked to amyotrophic lateral sclerosis (ALS), it was thought that ALS is a disease of oxidative stress, but this idea has taken a back seat since the discovery of multiple ALS-linked genes involved in RNA processing and proteostasis. Strikingly, a hallmark of both familial and sporadic ALS is the aggregation of the essential DNA/RNA binding protein TDP-43, which is thought to cause simultaneous loss-of-nuclear function and gain-of-cytoplasmic toxicity. A central unanswered question is what triggers ALS in adult followed by rapid and irreversible progression? Here we report that neuronal cells are particularly prone to oxidative stress to trigger TDP-43 aggregation, which in turn sponges a large subset of microRNAs and proteins, resulting in global mitochondrial imbalance that further elevates the oxidative stress. We propose that this ferocious cycle may underlie ALS onset and progression with oxidative stress as a key disease-driving event.
2020-10-12 | GSE126801 | GEO
Project description:When mutant superoxide dismutase 1 (SOD1) was first linked to amyotrophic lateral sclerosis (ALS), it was thought that ALS is a disease of oxidative stress. Since the discovery of multiple ALS-linked genes involved in RNA processing and proteostasis, most recent research has been focused on molecular defects induced by those mutant genes, but whether and how oxidative stress might contribute to magnification of those molecular defects have remained unaddressed. Strikingly, a hallmark of both familial and sporadic ALS is the aggregation of the essential DNA/RNA binding protein TDP-43, which is thought to cause simultaneous loss-of-nuclear function and gain-of-cytoplasmic toxicity. A central unanswered question is what triggers ALS in adult followed by rapid and irreversible progression? Here we report that neuronal cells are particularly prone to oxidative stress to trigger TDP-43 aggregation, which in turn sponges a large subset of microRNAs and proteins to cause both up-regulation and functional depletion of different sets of gene products. Remarkably, a large fraction of those functionally perturbed genes are nuclear genome-encoded mitochondrial proteins, thus resulting in a global mitochondrial imbalance, which further augments oxidative stress. We propose that this ferocious cycle driven by oxidative stress in combination with causal mutations in critical genes may underlie ALS onset and progression.
2020-11-20 | PXD021880 | Pride
Project description:Functional abnormality of TAR DNA-binding protein 43 (TDP-43), an aggregation-prone RNA and DNA binding protein, is observed in the vast majority of both familial and sporadic ALS cases and in ~40% of FTLD cases, but the cascade of events leading to cell death are not understood. We have expressed human TDP-43 (hTDP-43) in Drosophila neurons and glia, a model that recapitulates many of the characteristics of TDP-43-linked human disease including protein aggregation pathology, locomotor impairment, and premature death. We report that such expression of hTDP-43 impairs small interfering RNA (siRNA) silencing, which is the major post-transcriptional mechanism of retrotransposable element (RTE) control in somatic tissue. This is accompanied by de-repression of a panel of both LINE and LTR families of RTEs, with somewhat different elements being active in glia vs neurons. hTDP-43 expression in glia causes an early and severe loss of control of a specific RTE, the endogenous retrovirus (ERV) gypsy. We demonstrate that gypsy causes the degenerative phenotypes in these flies because we are able to rescue the toxicity of glial hTDP-43 either by genetically blocking expression of this RTE or by pharmacologically inhibiting RTE reverse transcriptase activity. Moreover, we provide evidence that activation of DNA damage-mediated programmed cell death underlies both neuronal and glial hTDP-43 toxicity, consistent with RTE-mediated effects in both cell types. Our findings suggest a novel mechanism in which RTE activity contributes to neurodegeneration in TDP-43-mediated diseases such as ALS and FTLD.
2017-02-15 | GSE85398 | GEO
Project description:This SuperSeries is composed of the following subset Series: GSE40649: Divergent roles of ALS-linked proteins FUS/TLS and TDP-43 intersect in processing long pre-mRNAs (microarray) GSE40651: Divergent roles of ALS-linked proteins FUS/TLS and TDP-43 intersect in processing long pre-mRNAs (CLIP-Seq) GSE40652: Divergent roles of ALS-linked proteins FUS/TLS and TDP-43 intersect in processing long pre-mRNAs (RNA-Seq) Refer to individual Series
2012-09-30 | E-GEOD-40653 | biostudies-arrayexpress
Project description:Protein aggregation is a hallmark of many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). Although mutations in TARDBP, encoding TDP-43, account for less than 1% of all ALS cases, TDP-43-positive aggregates are present in nearly all ALS patients, including patients with sporadic ALS (sALS) or carrying other familial ALS (fALS)-causing mutations. Interestingly, TDP-43 inclusions are also present in subsets of patients with frontotemporal dementia, Alzheimer’s disease, and Parkinson’s disease; therefore, methods of activating intracellular protein quality control machinery capable of clearing toxic cytoplasmic TDP-43 species may alleviate disease-related phenotypes. Here, we identify a novel function of Nemo-like kinase (Nlk) as a negative regulator of lysosome biogenesis. Genetic or pharmacological reduction of Nlk increased lysosome formation and improved clearance of aggregated TDP-43. Furthermore, Nlk reduction ameliorated pathological, behavioral, and lifespan deficits in two distinct mouse models of TDP-43 proteinopathy. Because many toxic proteins can be cleared along the autophagy-lysosome axis, targeted reduction of Nlk represents a potential approach to therapy development for multiple neurodegenerative disorders.
2023-06-24 | GSE235312 | GEO
Project description:Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the dysfunction and progressive death of cerebral and spinal motor neurons. Preliminary epidemiological research has hinted at a relationship between environmental risks and the escalation of ALS, but the underlying reasons remain mostly mysterious. Here, we show that nano-size polystyrene plastics (PS) induce ALS-like symptoms and illustrate the related molecular mechanism. When exposed to PS, cells endure internal oxidative stress, which leads to the aggregation of TAR DNA-binding protein 43 kDa (TDP-43), triggering ALS-like characteristics. Additionally, the oxidized heat shock protein 70 fails to escort TDP-43 back to the nucleus. The cytoplasmic accumulation of TDP-43 facilitates the formation of a complex between PS and TDP-43, enhancing TDP-43’s condensation and solidification. These findings are corroborated through in silico and in vivo assays. Altogether, our work illustrates a unique toxicological mechanism induced by nanoparticles and provides insights into the connection between environmental pollution and neurodegenerative disorders.
2024-04-19 | GSE264018 | GEO
Project description:We report the enrichment of mRNAs with motor neuron specific TDP-43 and tagged ribosomes in control as well as multiple models of TDP-43 induced neurodegeneration. Amyotrophic lateral sclerosis (ALS) is a genetically heterogeneous neurodegenerative disease in which 97% of patients exhibit cytoplasmic aggregates containing the RNA binding protein TDP-43. The goal of this study is to understand the translational consequences of TDP-43 pathology. Using the GAL4-UAS system, we expressed TDP-43WT and TDP-43G298S in the motor neurons of our drosophila to induce ALS-like neurodegeneration. TDP-43 was immunoprecipitated from the larvae at the 3rd instar stage; TDP-43 associated mRNAs, the whole larvae input, and ventral nerve cords of the same genotype were then sequenced. To identify translational changes we conducted TRAP (translating ribosome affinity purifications) in 3rd instar larvae by immunoprecipitating the motor neuron specific tagged ribosomal subunit RpL10-GFP in both ALS models as well as a RpL10-GFP control. The RpL10-GFP associated mRNAs, the whole larval input, and ventral nerve cords of the same genotype. From this data, we identified both compensatory alterations to translation induced by TDP-43 pathology and direct targets of TDP-43 mediated translational inhibition.
2021-03-31 | GSE156222 | GEO
Project description:Through splicing analysis of a publicly available RNA-Seq dataset, we discovered TDP-43 represses a cryptic exon splicing event in UNC13A, a gene that had been associated with FTD/ALS through GWA studies. To confirm the sequences of the cryptic exons, we used shRNA to reduce TDP-43 levels in iPSC-derived motor neurons (iPSC-MNs) and by amplicon sequencing the RT-PCR product, we observed the insertion in cells with TDP-43 depletion but not in control shRNA-treated cells. Through sequence alignment, we verified the sequences of the cryptic exons.
2021-12-04 | GSE182976 | GEO
Project description:The pathological hallmark of amyotrophic lateral sclerosis (ALS) is the presence of cytoplasmic inclusions, containing C-terminal fragments of the protein TDP-43. Here, we tested the hypothesis that highly sensitive mass spectrometry with parallel reaction monitoring (MS-PRM) can generate a high-resolution map of pathological TDP-43 peptide ratios to form the basis for quantitation of abnormal C-terminal TDP-43 fragment enrichment. Human cortex and spinal cord, microscopically staged for the presence of phosphoTDP-43, p-tau, alpha-synuclein and beta-amyloid pathology, were biochemically fractionated and analysed by immunoblot and MS for detection of full-length and truncated (disease-specific) TDP-43 peptides. This informed synthesis of heavy isotope-labelled peptides for the absolute quantification of TDP-43 by MS-PRM across 16 ALS, 8 Parkinson’s and 8 Alzheimer’s disease and 8 aged control cases. We confirmed by immunoblot the previously described enrichment of pathological C-terminal fragments in ALS-TDP urea fractions. Subsequent MS analysis resolved specific TDP-43 N- and C-terminal peptides, including a novel N-terminal truncation site-specific peptide. Absolute quantification of peptides by MS-PRM showed an increased C:N-terminal TDP-43 peptide ratio in ALS-TDP brain compared to normal and disease controls. A C:N-terminal ratio >1.5 discriminated ALS from controls with a sensitivity of 100% (CI 79.6-100) and specificity of 100% (CI 68-100), and from Parkinson’s and Alzheimer’s disease with a sensitivity of 93% (CI 70-100) and specificity of 100% (CI 68-100). N-terminal Truncation site-specific peptides were increased in ALS in line with C-terminal fragment enrichment, but also found in a proportion of Alzheimer cases with normal C:N-terminal ratio but coexistent TDP-43 pathology. In conclusion this is a novel, sensitive and specific method to quantify the enrichment of pathological TDP-43 fragments in human brain, which could form the basis for an antibody-free assay. Our methodology has the potential to help clarify if specific pathological TDP-43 peptide signatures are associated with primary or secondary TDP-43 proteinopathies.
2020-12-17 | PXD022186 | Pride
Project description:The discovery that TDP-43 mutations cause familial ALS and that many patients display pathological TDP-43 mislocalization has nominated altered RNA metabolism as a potential disease mechanism. Despite its importance, the identity of RNAs regulated by TDP-43 in motor neurons remains poorly understood. Here, we report transcripts whose abundances in human motor neurons are sensitive to TDP-43 depletion. Notably, we found STMN2, which encodes a microtubule regulator, declined after TDP-43 knockdown, in patient-specific motor neurons, following TDP-43 mislocalization, and in the postmortem patient spinal cords. Loss of STMN2 upon reduced TDP-43 function was due to the emergence of a cryptic exon, which is of substantial functional importance, as we further demonstrate that STMN2 is necessary for both axonal outgrowth and repair. Importantly, post-translational stabilization of STMN2 could rescue neurite outgrowth and axon regeneration deficits induced by TDP-43 depletion. We propose restoring STMN2 expression warrants future examination as an ALS therapeutic strategy.
2019-01-15 | GSE121569 | GEO