The abnormal repetition of the hexanucleotide GGGGCC within the C9orf72 gene is the most common genetic cause of both Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). Different hypothesis have been proposed to explain the pathogenicity of this mutation. Among them, the production of aberrant proteins called Dipeptide Repeat Proteins (DPR) from the repeated sequence. Those proteins are of interest, as they are toxic and form insoluble deposits in patient brains. In this study, we characterized the structural features of three different DPR encoded by the hexanucleotide repeat GGGGCC, namely poly-GA, poly-GP and poly-PA. We showed that DPR are natively unstructured proteins and that only poly-GA forms in vitro fibrillary aggregates. Poly-GA fibrils are of amyloid nature as revealed by their high content in beta sheets. They neither bind Thioflavin T nor Primuline, the commonly used amyloid fluorescent dyes. Remarkably, not all of the poly-GA primary structure was part of fibrils amyloid core.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.bbrc.2020.03.108 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Drug Development.
Alzheimers Dement
December 2024
UCSF Weill Institute for Neurosciences, San Francisco, CA, USA.
Background: Efforts to genetically reverse C9orf72 pathology have been hampered by our incomplete understanding of the regulation of this complex locus.
Method: We generated five different genomic excisions at the C9orf72 locus in a patient-derived iPSC line and a WT line (11 total isogenic lines), and examined gene expression and pathological hallmarks of C9 FTD/ALS in motor neurons differentiated from these lines. Comparing the excisions in these isogenic series removed the confounding effects of different genomic backgrounds and allowed us to probe the effects of specific genomic changes.
The most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) is an intronic GC repeat expansion in C9orf72. The repeats undergo bidirectional transcription to produce sense and antisense repeat RNA species, which are translated into dipeptide repeat proteins (DPRs). As toxicity has been associated with both sense and antisense repeat-derived RNA and DPRs, targeting both strands may provide the most effective therapeutic strategy.
View Article and Find Full Text PDFA high-fidelity CRISPR-Cas13 system improves abnormalities associated with C9ORF72-linked ALS/FTD.
Nat Commun
January 2025
Department of Bioengineering, The Grainger College of Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA.
An abnormal expansion of a GGGGCC (GC) hexanucleotide repeat in the C9ORF72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two debilitating neurodegenerative disorders driven in part by gain-of-function mechanisms involving transcribed forms of the repeat expansion. By utilizing a Cas13 variant with reduced collateral effects, we develop here a high-fidelity RNA-targeting CRISPR-based system for C9ORF72-linked ALS/FTD. When delivered to the brain of a transgenic rodent model, this Cas13-based platform curbed the expression of the GC repeat-containing RNA without affecting normal C9ORF72 levels, which in turn decreased the formation of RNA foci, reduced the production of a dipeptide repeat protein, and reversed transcriptional deficits.
View Article and Find Full Text PDFNLS-binding deficient Kapβ2 reduces neurotoxicity via selective interaction with C9orf72-ALS/FTD dipeptide repeats.
Commun Biol
January 2025
Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA.
Arginine-rich dipeptide repeat proteins (R-DPRs) are highly toxic proteins found in patients with C9orf72-linked amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). R-DPRs can cause toxicity by disrupting the natural phase behavior of RNA-binding proteins (RBPs). Mitigating this abnormal phase behavior is, therefore, crucial to reduce R-DPR-induced toxicity.
View Article and Find Full Text PDFA robust evaluation of TDP-43, poly GP, cellular pathology and behavior in an AAV-C9ORF72 (GC) mouse model.
Acta Neuropathol Commun
December 2024
Brain Science Institute, Johns Hopkins University School of Medicine, Johns Hopkins University, 855 N. Wolfe St., Rangos 275, Baltimore, MD, 21205, USA.
The GC hexanucleotide repeat expansion in C9ORF72 is the major genetic cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9-ALS/FTD). Despite considerable efforts, the development of mouse models of C9-ALS/FTD useful for therapeutic development has proven challenging due to the intricate interplay of genetic and molecular factors underlying this neurodegenerative disorder, in addition to species differences. This study presents a robust investigation of the cellular pathophysiology and behavioral outcomes in a previously described AAV mouse model of C9-ALS expressing 66 GC hexanucleotide repeats.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!