Bulk neocortical RNA sequencing of rNLS8 mice (on mixed C57BL/6J × C3H/HeJ background ) +/- active immunization with C-terminal hTDP-43 antigens
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ABSTRACT: This data set reports RNA sequencing results obtained from whole cerebral cortices of NEFH-tTa/tetO-hTDP43∆NLS transgenic (“rNLS8”) mice that were actively immunized with C-terminal fragments of the human TDP-43 protein. The widely used rNLS8 mouse model overexpresses cytoplasmically mislocalized human TDP-43 in a doxycycline-inducible manner, mimicking ALS/FTD-like CNS pathology and motor dysfunction (Walker et al., 2015). The purpose of this study was to evaluate the safety profile and therapeutic potential of various human TDP-43 epitopes (up to approximately 40 amino acids in length) which were used as antigens for active immunization in a rapidly progressing mouse model of TDP-43 proteinopathy. To this end, we pre-screened 15 peptide antigens, collectively spanning the entire TDP-43 protein sequence, for immunogenicity and safety. Next, we repeatedly immunized “rNLS8” mice with the most promising antigens prior to transgene induction, and performed bulk RNA sequencing of the neocortex, since this region is considerably affected by TDP-43 pathology in both humans and the mouse model. We asked whether active immunization with two different peptide combinations leading to high antibody titers would affect – i.e. prevent – transcriptional alterations upon transgene induction. In summary, we provide a bulk neocortical gene expression profile of actively immunized (and mock-treated) ALS/FTD-resembling “rNLS8” mice.
Project description:Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) share key features, including accumulation of the RNA binding protein TDP-43. TDP-43 regulatesRNA homeostasis, but it remains unclear whether RNA stability is affected in these disorders. We used Bru-seq and BruChase-seq to assessgenome-wide RNA stabilityinALS patient-derived cells,demonstratingprofound destabilization of ribosomal and mitochondrial transcripts. This pattern wasrecapitulatedbyTDP-43 overexpression, suggesting a primary role for TDP-43 in RNA destabilization, and in post-mortem samples from ALS and FTD patients. Proteomics and functional studies illustrated corresponding reductionsin mitochondrial components and compensatory increasesin protein synthesis. Collectively, these observations suggest that TDP-43 deposition leads to targeted RNA instability in ALS and FTD, ultimately causing cell death by disrupting energy production and protein synthesis pathways.
Project description:Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are associated with loss of nuclear TDP-43. Here we identify that TDP-43 regulates expression of the neuronal growth-associated factor stathmin-2. Lowered TDP-43 levels, which reduce its binding to sites within the first intron of stathmin-2 pre-mRNA, uncover a cryptic polyadenylation site whose utilization produces a truncated, non-functional mRNA. Reduced stathmin-2 expression is found in neurons trans-differentiated from patient fibroblasts expressing an ALS-causing TDP-43 mutation, in motor cortex and spinal motor neurons from sporadic ALS patients and familial ALS patients with expansion in C9orf72, and in induced pluripotent stem cell (iPSC)-derived motor neurons depleted of TDP-43. Remarkably, while reduction in TDP-43 is shown to inhibit axonal regeneration of iPSC-derived motor neurons, rescue of stathmin-2 expression restores axonal regenerative capacity. Thus, premature polyadenylation-mediated reduction in stathmin-2 is a hallmark of ALS/FTD that functionally links reduced nuclear TDP-43 function to enhanced neuronal vulnerability.
Project description:Both gain of toxicity and loss of normal function of the RNA-binding protein TDP-43 contribute to neurodegeneration in ALS and FTD, but their mechanistic connection remains unclear. Increasing evidence suggests that TDP-43 aggregates act as self-templating seeds, propagating pathology through the central nervous system via a prion-like cascade. We developed a robust TDP-43 seeding platform for quantitative, high-throughput assessment of TDP-43 aggregate uptake, cell-to-cell spreading and direct quantification of TDP-43 nuclear function within living cells, while they progress towards pathology. We show that both patient-derived and recombinant TDP-43 pathological aggregates are abundantly internalized in human neuron-like cells, efficiently recruit endogenous TDP-43 and form cytoplasmic inclusions reminiscent of ALS/FTD pathology. These neoaggregates progressively drive the nuclear egress of TDP-43 leading to its loss of function. The scope of this project is to identify the signatures involved in the progressive egress of TDP-43 from the nucleus to the cytoplasm.
Project description:Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) share key features, including accumulation of the RNA binding protein TDP-43. TDP-43 regulates RNA homeostasis, but it remains unclear whether RNA stability is affected in these disorders. We use Bru-seq and BruChase-seq to assess genome-wide RNA stability in ALS patient-derived cells, demonstrating profound destabilization of ribosomal and mitochondrial transcripts. This pattern is recapitulated by TDP-43 overexpression, suggesting a primary role for TDP-43 in RNA destabilization, and in post-mortem samples from ALS and FTD patients. Proteomics and functional studies illustrate corresponding reductions in mitochondrial components and compensatory increases in protein synthesis. Collectively, these observations suggest that TDP-43 deposition leads to targeted RNA instability in ALS and FTD, and may ultimately cause cell death by disrupting energy production and protein synthesis pathways.
Project description:Maintaining cholesterol homeostasis is essential for health of all animal cells. Because of blood-brain barrier, de novo cholesetrol biosynthesis and intercellular cholesterol transport is thought to maintain cholesterol homeostasis within the central nervous system (CNS). Here, we showed that TDP-43, the pathological signature protein for amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), regulates SREBF2-mediated cholesterol metabolism in the central nervous system (CNS). Unbiased transcriptomic analysis of mice with oligodendroglial TDP-43 deletion revealed a progressive and pathway-wide disruption in the cholesterol metabolism correlating with reduced myelination and cholesterol level. Molecularly, TDP-43 binds directly to mRNA of SREBF2, the master transcription regulator for cholesterol metabolism, and multiple mRNAs encoding proteins in the cholesterol biosynthesis and uptake, including HMGCR, HMGCS1, and LDLR. Depletion of TDP-43 leads to reduced SREBF2 and cholesterol level in vitro and in vivo. The cholesterol reduction can be rescued by reintroducing either the nuclear portion of SREBF2 or LDLR, the latter of which is the receptor for cholesterol-containing low-density lipoproteins (LDLs). Furthermore, LDLR are observed to co-aggregate with pathological TDP-43 in oligodendrocytes of FTD patients and motor neurons of sporadic ALS patients. Taken together, our data indicates that TDP-43 is required to maintain SREBF2-dependent cholesterol homeostasis in the CNS, and disturbance of cholesterol metabolism may be involved in ALS, FTD and TDP-43 proteinopathies-related disease.
Project description:Understanding the mechanisms that drive TDP-43 pathology is integral to combating amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Here we generated a longitudinal quantitative proteomic map of the cortex from the cytoplasmic TDP-43 rNLS8 mouse model of ALS and FTLD and developed a complementary open-access webtool, TDP-map (https://shiny.rcc.uq.edu.au/TDP-map/). We identified distinct protein subsets enriched for diverse biological pathways with temporal alterations in protein abundance, including increases in protein folding factors prior to disease onset. This included increased levels of DnaJ homolog subfamily B member 5, DNAJB5, which also co-localized with TDP-43 pathology in diseased human motor cortex. DNAJB5 over-expression decreased TDP-43 aggregation in cell and cortical neuron cultures, and knockout of Dnajb5 exacerbated motor impairments caused by AAV-mediated cytoplasmic TDP-43 expression in mice. Together, these findings reveal molecular mechanisms at distinct stages of ALS and FTLD progression and suggest that protein folding factors could be protective in disease.
Project description:Neurodegeneration in ALS and FTD results from both gain of toxicity and loss of normal function of the RNA-binding protein TDP-43, but their mechanistic connection remains unclear. Increasing evidence suggests that TDP-43 aggregates act as self-templating seeds, propagating pathology through the central nervous system via a prion-like cascade. We developed a robust TDP-43 seeding platform for quantitative, high-throughput assessment of TDP-43 aggregate uptake, cell-to-cell spreading and loss of function within living cells, while they progress towards pathology. We show that both patient-derived and recombinant TDP-43 pathological aggregates were abundantly internalized in human neuron-like cells, efficiently recruited endogenous TDP-43 and formed cytoplasmic inclusions reminiscent of ALS/FTD pathology. These neoaggregates progressively drove the nuclear egress of TDP-43 leading to its loss of function. Our model demonstrates the link between TDP-43 aggregation and aberrant cryptic splicing and provides new tools to identify genetic or pharmacologic modifiers of each step in the process.
Project description:No treatment for frontotemporal dementia (FTD), the second most common type of early-onset dementia, is available, but therapeutics are being investigated to target the 2 main proteins associated with FTD pathological subtypes: TDP-43 (FTLD-TDP) and tau (FTLD-tau). Testing potential therapies in clinical trials is hampered by our inability to distinguish between patients with FTLD-TDP and FTLD-tau. Therefore, we evaluated truncated stathmin-2 (STMN2) as a proxy of TDP-43 pathology, given the reports that TDP-43 dysfunction causes truncated STMN2 accumulation. Truncated STMN2 accumulated in human induced pluripotent stem cell–derived neurons depleted of TDP-43, but not in those with pathogenic TARDBP mutations in the absence of TDP-43 aggregation or loss of nuclear protein. In RNA-Seq analyses of human brain samples from the NYGC ALS cohort, truncated STMN2 RNA was confined to tissues and disease subtypes marked by TDP-43 inclusions. Last, we validated that truncated STMN2 RNA was elevated in the frontal cortex of a cohort of patients with FTLD-TDP but not in controls or patients with progressive supranuclear palsy, a type of FTLD-tau. Further, in patients with FTLD-TDP, we observed significant associations of truncated STMN2 RNA with phosphorylated TDP-43 levels and an earlier age of disease onset. Overall, our data uncovered truncated STMN2 as a marker for TDP-43 dysfunction in FTD.
Project description:Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) represent two ends of a disease spectrum with shared clinical, genetic and pathological features. These include near ubiquitous pathological inclusions of the RNA binding protein (RBP) TDP-43, and often the presence of a GGGGCC expansion in the C9ORF72 (C9) gene. Here we show unexpectedly that the signature of hnRNP H sequestration and altered splicing of target transcripts we identified in C9ALS patients (Conlon et al. 2016) also occurs in fully half of 50 post-mortem sporadic, non-C9 ALS/FTD post-mortem brains. Furthermore, and equally surprisingly, these “like-C9” brains also contained correspondingly high amounts of insoluble TDP-43, as well as several other disease-related RBPs, and this correlates with widespread global splicing defects. Finally, we show that the like-C9 sporadic patients, like actual C9ALS patients, were much more likely to have developed FTD. We propose that these unexpected links between C9 and sporadic ALS/FTD define a common mechanism in this disease spectrum.
Project description:Mutation in TDP-43 is causative to amyotrophic lateral sclerosis (ALS). TDP-43 is a multifunctional ribonucleoprotein and is reproted to regulate thousands of genes in neurons, but how astrocytes contribute to TDP-43 pathogenesis is not known. This study examined how mutant TDP-43 in astrocytes kills motor neurons and causes ALS phenotypes. Primary astrocytes were isolated from transgenic rats expressing mutant TDP-43 or from control rats without mutant TDP-43 expression. Cultured astrocytes were induced to express mutant human TDP-43 and their gene expression profiles were determined by microarray assays. Microarray analysis revealed that hundreds of genes were altered in astrocytes in response to mutant TDP-43 expression. As mutant TDP-43 transgene is under the control of tetracycline-regulated pomoter elements (TRE), mutant TDP-43 expression is subjected to Doxycline regulation. Astrocytes isolated from GFAP-tTA/TRE-TDP43M337V rats were desiginated as M337V groups and astrocytes isolated from GFAP-tTA single transgenic rats were desiginated as tTA control groups. Total RNA was isolated from cultured astrocytes at varying times (3, 4, or 6 days after Dox withdrawal) after mutant TDP-43 was induced in astrocytes. Upon mutant TDP-43 induction in astroyctes, gene expression profiles in astroyctes were determined by Illumina Direct Hybridization Assay and compared between tTA and M337V groups at the varying time points of mutant TDP-43 induction.