CLIP-Seq Analysis Enables the Design of Ribosomal RNA Bait Oligonucleotides That Protect Against C9ORF72 ALS/FTD-Associated Poly-GR Pathophysiology
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE182008 | GEO | 2023/11/13
REPOSITORIES: GEO
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Project description:Amyotrophic lateral sclerosis and frontotemporal dementia patients with a hexanucleotide repeat expansion in C9ORF72 (C9-HRE) accumulate poly-GR and poly-PR aggregates. The pathogenicity of these arginine-rich dipeptide repeats (R-DPRs) is thought to be driven by their propensity to bind low-complexity domains of multivalent proteins. However, the ability of R-DPRs to bind native RNA and the significance of this interaction remain unclear. Here, we used computational and experimental approaches to characterize the physicochemical properties of R-DPRs and their interaction with RNA. We find that poly-GR predominantly binds ribosomal RNA (rRNA) in cells and exhibits an interaction that is predicted to be energetically stronger than that for associated ribosomal proteins. Critically, modified rRNA "bait" oligonucleotides restore poly-GR-associated ribosomal deficits and ameliorate poly-GR toxicity in patient neurons and Drosophila models. Our work strengthens the hypothesis that ribosomal function is impaired by R-DPRs, highlights a role for direct rRNA binding in mediating ribosomal dysfunction, and presents a strategy for protecting against C9-HRE pathophysiological mechanisms.
| S-EPMC10637751 | biostudies-literature
Project description:Hexanucleotide repeat expansion in the C9ORF72 gene is the most frequent inherited cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Poly-GR is one of the most toxic dipeptide repeat (DPR) proteins translated from the RNA repeats. It has been shown to affect protein synthesis, but how this contributes to neurodegeneration is not clear. Here, we found that poly-GR inhibits global translation by perturbing translation elongation. We identified that the transcripts with relatively slow elongation rate tend to be further stalled by poly-GR in iPSC-differentiated neurons. This increases ribosome collision and ZAKα-mediated ribotoxic stress response (RSR), which elevates the phosphorylation of p38 and promotes cell death. Knockdown of ZAKα or pharmacological inhibition of p38 can ameliorate the GR toxicity, and improve the survival of C9ORF72-ALS/FTD patient-derived iPSC-neurons. Our study reveals molecular mechanism of poly-GR mediated toxicity on global translatome, and identifies RSR as a potential therapeutic target for C9ORF72-ALS/FTD.
2024-08-23 | GSE230127 | GEO
Project description:CLIP-Seq Analysis Enables the Design of Ribosomal RNA Bait Oligonucleotides That Protect Against C9ORF72 ALS/FTD-Associated Poly-GR Pathophysiology
| PRJNA754172 | ENA
Project description:Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) patients with the C9orf72 mutation show predominantly cytoplasmic aggregates of poly-GR and poly-PR proteins that are acutely toxic in various model systems. To identify the molecular mediators of neurotoxicity of poly-GR/PR, we analyzed their interactomes in primary neurons. GFP-(GR)149 and (PR)175-GFP preferentially interacted with RNA-binding proteins, including stress granule-associated and nucleolar proteins, as well as ribosomes. Overexpression of the poly-GR/PR interactors Staufen 1/2 (STAU1/2) and YBX1 led to cytoplasmic aggregation of poly-GR/PR into large stress granule-like inclusions, while the poly-GR/PR interactor nucleophosmin (NPM1) recruited poly-GR into the nucleolus. In addition, poly-PR expression reduced ribosome levels and translation, which is consistent with the widespread reduction of synaptic proteins detected by proteomics. Surprisingly, only GFP-(GR)53, but not GFP-(GR)149, localized to the nucleolus and reduced ribosome levels and translation in neurons, suggesting impaired ribosome biogenesis is driving the acute toxicity commonly observed in vitro. In C9orf72 patient brains, we detected co-aggregation of poly-GR/PR inclusions with ribosomes, but not stress granules. Partial sequestration of ribosomes may chronically impair protein synthesis and contribute to C9orf72 ALS/FTD pathogenesis.
2018-06-27 | PXD008691 | Pride
Project description:The GGGGCC repeat expansion in C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, it is not known which dysregulated molecular pathways are primarily responsible for disease initiation or progression. We established an inducible mouse model of poly(GR) toxicity in which (GR)80 gradually accumulates in cortical excitatory neurons. Low-level poly(GR) expression induced FTD/ALS-associated synaptic dysfunction and behavioral abnormalities, as well as age-dependent neuronal cell loss, microgliosis and DNA damage, probably caused in part by early defects in mitochondrial function. Poly(GR) bound preferentially to the mitochondrial complex V component ATP5A1 and enhanced its ubiquitination and degradation, consistent with reduced ATP5A1 protein level in both (GR)80 mouse neurons and patient brains. Moreover, inducing ectopic Atp5a1 expression in poly(GR)-expressing neurons or reducing poly(GR) level in adult mice after disease onset rescued poly(GR)-induced neurotoxicity. Thus, poly(GR)-induced mitochondrial defects are a major driver of disease initiation in C9ORF72-related ALS/FTD.
| S-EPMC6800116 | biostudies-literature
Project description:Poly-GR impairs translation elongation and increases ribotoxic stress response in C9ORF72-ALS/FTD
| PRJNA957700 | ENA
Project description:GGGGCC repeat expansion in C9ORF72, which can be translated in both sense and antisense directions into five dipeptide repeat (DPR) proteins, including poly(GP), poly(GR), and poly(GA), is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Here we developed sensitive assays that can detect poly(GA) and poly(GR) in the cerebrospinal fluid (CSF) of patients with C9ORF72 mutations. CSF poly(GA) and poly(GR) levels did not correlate with age at disease onset, disease duration, or rate of decline of ALS Functional Rating Scale, and the average levels of these DPR proteins were similar in symptomatic and pre-symptomatic patients with C9ORF72 mutations. However, in a patient with C9ORF72-ALS who was treated with antisense oligonucleotide (ASO) targeting the aberrant C9ORF72 transcript, CSF poly(GA) and poly(GR) levels decreased approximately 50% within 6 weeks, indicating they may serve as sensitive fluid-based biomarkers in studies directed against the production of GGGGCC repeat RNAs or DPR proteins.
| S-EPMC9119980 | biostudies-literature
Project description:Expanded intronic G4C2 repeats in the C9ORF72 gene cause amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). These intronic repeats are translated through a non-AUG-dependent mechanism into five different dipeptide repeat proteins (DPRs), including poly-glycine-arginine (GR), which is aggregation-prone and neurotoxic. Here, we report that Kapβ2 and GR interact, co-aggregating, in cultured neurons in-vitro and CNS tissue in-vivo. Importantly, this interaction significantly decreased the risk of death of cultured GR-expressing neurons. Downregulation of Kapβ2 is detrimental to their survival, whereas increased Kapβ2 levels mitigated GR-mediated neurotoxicity. As expected, GR-expressing neurons displayed TDP-43 nuclear loss. Raising Kapβ2 levels did not restore TDP-43 into the nucleus, nor did alter the dynamic properties of GR aggregates. Overall, our findings support the design of therapeutic strategies aimed at up-regulating Kapβ2 expression levels as a potential new avenue for contrasting neurodegeneration in C9orf72-ALS/FTD.
| S-EPMC10978903 | biostudies-literature
Project description:C9ORF72-derived dipeptide repeat proteins have emerged as the pathogenic cause of neurodegeneration in amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). However, the mechanisms underlying their expression are not fully understood. Here, we demonstrate that ZNF598, the rate-limiting factor for ribosome-associated quality control (RQC), co-translationally titrates the expression of C9ORF72-derived poly(GR) protein. A Drosophila genetic screen identified key RQC factors as potent modifiers of poly(GR)-induced neurodegeneration. ZNF598 overexpression in human neuroblastoma cells inhibited the nuclear accumulation of poly(GR) protein and decreased its cytotoxicity, whereas ZNF598 deletion had opposing effects. Poly(GR)-encoding sequences in the reporter RNAs caused translational stalling and generated ribosome-associated translation products, sharing molecular signatures with canonical RQC substrates. Furthermore, ZNF598 and listerin 1, the RQC E3 ubiquitin-protein ligase, promoted poly(GR) degradation via the ubiquitin-proteasome pathway. An ALS-relevant ZNF598R69C mutant displayed loss-of-function effects on poly(GR) expression, as well as on general RQC. Moreover, RQC function was impaired in C9-ALS patient-derived neurons, whereas lentiviral overexpression of ZNF598 lowered their poly(GR) expression and suppressed proapoptotic caspase-3 activation. Taken together, we propose that an adaptive nature of the RQC-relevant ZNF598 activity allows the co-translational surveillance to cope with the atypical expression of pathogenic poly(GR) protein, thereby acquiring a neuroprotective function in C9-ALS/FTD.
| S-EPMC8565315 | biostudies-literature
Project description:Toxic dipeptide-repeat (DPR) proteins are produced from expanded G4C2 repeats in the C9ORF72 gene, the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Two DPR proteins, poly-PR and poly-GR, repress cellular translation but the molecular mechanism remains unknown. Here we show that poly-PR and poly-GR of ≥20 repeats inhibit the ribosome's peptidyl-transferase activity at nanomolar concentrations, comparable to specific translation inhibitors. High-resolution cryogenic electron microscopy (cryo-EM) reveals that poly-PR and poly-GR block the polypeptide tunnel of the ribosome, extending into the peptidyl-transferase center (PTC). Consistent with these findings, the macrolide erythromycin, which binds in the tunnel, competes with poly-PR and restores peptidyl-transferase activity. Our results demonstrate that strong and specific binding of poly-PR and poly-GR in the ribosomal tunnel blocks translation, revealing the structural basis of their toxicity in C9ORF72-ALS/FTD.
| S-EPMC9120013 | biostudies-literature