scholarly journals Silencing of genes responsible for polyQ diseases using chemically modified single-stranded siRNAs

2017 ◽  
Vol 63 (4) ◽  
Author(s):  
Agnieszka Fiszer ◽  
Marianna E Ellison-Klimontowicz ◽  
Wlodzimierz J Krzyzosiak
Keyword(s):  
Genetic Disorders ◽  
Mutant Gene ◽  
Cag Repeat ◽  
Spinocerebellar Ataxia Type ◽  
Spinocerebellar Ataxia Type 3 ◽  
Mutation Site ◽  
Protein Levels ◽  
Cellular Models ◽  
Polyq Diseases ◽  
Type 3

Polyglutamine (polyQ) diseases comprise a group of nine genetic disorders that are caused by the expansion of the CAG triplet repeat, which encodes glutamine, in unrelated single genes. The pathogenesis is caused by the disruption of cellular pathways by the expression products of the mutant gene, i.e., proteins containing polyQ tracts and mutant transcripts. In considering oligonucleotide (ON)-based therapeutic approaches for polyQ diseases, the very attractive CAG repeat-targeting strategy offers selective silencing of the mutant allele by directly targeting the mutation site. CAG repeat-targeting miRNA-like siRNAs have been shown to specifically inhibit mutant gene expression, and their characteristic feature is the formation of mismatches in their interactions with the target site. Here, we designed novel single-stranded siRNAs that contain base substitutions and chemical modifications and tested these oligonucleotides in cellular models of Huntington’s disease (HD), spinocerebellar ataxia type 3 (SCA3) and dentatorubral-pallidoluysian atrophy (DRPLA), including HD mouse striatal cells. Selected siRNAs caused the efficient and selective downregulation of the mutant protein levels.

scholarly journals Praja1 ubiquitin ligase facilitates degradation of polyglutamine proteins and suppresses polyglutamine-mediated toxicity

2021 ◽  
pp. mbc.E20-11-0747
Author(s):  
Baijayanti Ghosh ◽  
Susnata Karmakar ◽  
Mohit Prasad ◽  
Atin K. Mandal
Keyword(s):  
Ubiquitin Ligase ◽  
Ubiquitin Ligases ◽  
Spinocerebellar Ataxia Type ◽  
Spinocerebellar Ataxia Type 3 ◽  
Protein Levels ◽  
Drosophila Model ◽  
Polyq Protein ◽  
Cytotoxic Stress ◽  
Polyq Diseases ◽  
Type 3

A network of chaperones and ubiquitin ligases sustain intracellular proteostasis, and is integral in preventing aggregation of misfolded proteins associated with various neurodegenerative diseases. Using cell-based studies of polyglutamine (polyQ) diseases: Spinocerebellar ataxia Type 3 (SCA3) and Huntington's disease (HD), we aimed to identify crucial ubiquitin ligases that protect against polyQ aggregation. We report here that Praja1 (PJA1), a Ring-H2 ubiquitin ligase abundantly expressed in the brain is diminished when polyQ repeat proteins (Ataxin-3/Huntingtin) are expressed in cells. PJA1 interacts with polyQ proteins and enhances their degradation resulting in reduced aggregate formation. Down-regulation of PJA1 in neuronal cells increases polyQ protein levels vis-a-vis their aggregates rendering the cells vulnerable to cytotoxic stress. Finally, PJA1 suppresses polyQ toxicity in yeast and rescues eye degeneration in transgenic Drosophila model of SCA3. Thus, our findings establish PJA1 as a robust ubiquitin ligase of polyQ proteins and induction of which might serve as an alternative therapeutic strategy in handling cytotoxic polyglutamine aggregates.

scholarly journals DNAzyme Cleavage of CAG Repeat RNA in Polyglutamine Diseases

2021 ◽  
Author(s):  
Nan Zhang ◽  
Brittani Bewick ◽  
Jason Schultz ◽  
Anjana Tiwari ◽  
Robert Krencik ◽  
...  
Keyword(s):  
Spinocerebellar Ataxia ◽  
Cag Repeat ◽  
Spinocerebellar Ataxia Type ◽  
Spinocerebellar Ataxia Type 3 ◽  
Therapeutic Value ◽  
Expanded Allele ◽  
Allele Specific ◽  
Aggresome Formation ◽  
Polyq Diseases ◽  
Type 3

AbstractCAG repeat expansion is the genetic cause of nine incurable polyglutamine (polyQ) diseases with neurodegenerative features. Silencing repeat RNA holds great therapeutic value. Here, we developed a repeat-based RNA-cleaving DNAzyme that catalyzes the destruction of expanded CAG repeat RNA of six polyQ diseases with high potency. DNAzyme preferentially cleaved the expanded allele in spinocerebellar ataxia type 1 (SCA1) cells. While cleavage was non-allele-specific for spinocerebellar ataxia type 3 (SCA3) cells, treatment of DNAzyme leads to improved cell viability without affecting mitochondrial metabolism or p62-dependent aggresome formation. DNAzyme appears to be stable in mouse brain for at least 1 month, and an intermediate dosage of DNAzyme in a SCA3 mouse model leads to a significant reduction of high molecular weight ATXN3 proteins. Our data suggest that DNAzyme is an effective RNA silencing molecule for potential treatment of multiple polyQ diseases.

scholarly journals RAN translation of the expanded CAG repeats in the SCA3 disease context

2020 ◽  
Author(s):  
Magdalena Jazurek-Ciesiolka ◽  
Adam Ciesiolka ◽  
Alicja A. Komur ◽  
Martyna O. Urbanek-Trzeciak ◽  
Agnieszka Fiszer
Keyword(s):  
Cellular Localization ◽  
Neurodegenerative Disorder ◽  
Cag Repeat ◽  
Cag Repeats ◽  
Spinocerebellar Ataxia Type ◽  
Gene Encoding ◽  
Spinocerebellar Ataxia Type 3 ◽  
Cellular Models ◽  
Type 3 ◽  
Ran Translation

ABSTRACTSpinocerebellar ataxia type 3 (SCA3) is a progressive neurodegenerative disorder caused by a CAG repeat expansion in the ATXN3 gene encoding the ataxin-3 protein. Despite extensive research the exact pathogenic mechanisms of SCA3 are still not understood in depth. In the present study, to gain insight into the toxicity induced by the expanded CAG repeats in SCA3, we comprehensively investigated repeat-associated non-ATG (RAN) translation in various cellular models expressing translated or non-canonically translated ATXN3 sequences with an increasing number of CAG repeats. We demonstrate that two SCA3 RAN proteins, polyglutamine (polyQ) and polyalanine (polyA), are found only in the case of CAG repeats of pathogenic length. Despite having distinct cellular localization, RAN polyQ and RAN polyA proteins are very often coexpressed in the same cell, impairing nuclear integrity and inducing apoptosis. We provide for the first time mechanistic insights into SCA3 RAN translation indicating that ATXN3 sequences surrounding the repeat region have an impact on SCA3 RAN translation initiation and efficiency. We revealed that RAN translation of polyQ proteins starts at non-cognate codons upstream of the CAG repeats, whereas RAN polyA proteins are likely translated within repeats. Furthermore, integrated stress response activation enhances SCA3 RAN translation. We suggest that RAN translation in SCA3 is a common event substantially contributing to SCA3 pathogenesis and that the ATXN3 sequence context plays an important role in triggering this unconventional translation.

scholarly journals Praja1 ubiquitin ligase facilitates degradation of polyglutamine proteins and suppresses polyglutamine-mediated toxicity

2020 ◽  
Author(s):  
Atin Kumar Mandal ◽  
Baijayanti Ghosh ◽  
Susnata Karmakar ◽  
Mohit Prasad
Keyword(s):  
Ubiquitin Ligase ◽  
Ubiquitin Ligases ◽  
Spinocerebellar Ataxia Type ◽  
Spinocerebellar Ataxia Type 3 ◽  
Protein Levels ◽  
Drosophila Model ◽  
Polyq Protein ◽  
Cytotoxic Stress ◽  
Polyq Diseases ◽  
Type 3

A network of chaperones and ubiquitin ligases sustain intracellular proteostasis, and is integral in preventing aggregation of misfolded proteins associated with various neurodegenerative diseases. Using cell-based studies of polyglutamine (polyQ) diseases: Spinocerebellar ataxia Type 3 (SCA3) and Huntingtons disease (HD), we aimed to identify crucial ubiquitin ligases that protect against polyQ aggregation. We report here that Praja1 (PJA1), a Ring-H2 ubiquitin ligase abundantly expressed in the brain is diminished when polyQ repeat proteins (Ataxin-3/Huntingtin) are expressed in cells. PJA1 interacts with polyQ proteins and enhances their degradation resulting in reduced aggregate formation. Down-regulation of PJA1 in neuronal cells increases polyQ protein levels vis-a-vis their aggregates rendering the cells vulnerable to cytotoxic stress. Finally, PJA1 suppresses polyQ toxicity in yeast and rescues eye degeneration in transgenic Drosophila model of SCA3. Thus, our findings establish PJA1 as a robust ubiquitin ligase of polyQ proteins and induction of which might serve as an alternative therapeutic strategy in handling cytotoxic polyglutamine aggregates.

scholarly journals A fine balance between Prpf19 and Exoc7 in achieving degradation of aggregated protein and suppression of cell death in spinocerebellar ataxia type 3

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Zhefan Stephen Chen ◽  
Xiaoying Huang ◽  
Kevin Talbot ◽  
Ho Yin Edwin Chan
Keyword(s):  
Spinocerebellar Ataxia ◽  
E3 Ligase ◽  
Spinocerebellar Ataxia Type ◽  
Disease Genes ◽  
Spinocerebellar Ataxia Type 3 ◽  
E3 Ligases ◽  
Protein Ubiquitination ◽  
Polyq Protein ◽  
Polyq Diseases ◽  
Type 3

AbstractPolyglutamine (polyQ) diseases comprise Huntington’s disease and several subtypes of spinocerebellar ataxia, including spinocerebellar ataxia type 3 (SCA3). The genomic expansion of coding CAG trinucleotide sequence in disease genes leads to the production and accumulation of misfolded polyQ domain-containing disease proteins, which cause cellular dysfunction and neuronal death. As one of the principal cellular protein clearance pathways, the activity of the ubiquitin–proteasome system (UPS) is tightly regulated to ensure efficient clearance of damaged and toxic proteins. Emerging evidence demonstrates that UPS plays a crucial role in the pathogenesis of polyQ diseases. Ubiquitin (Ub) E3 ligases catalyze the transfer of a Ub tag to label proteins destined for proteasomal clearance. In this study, we identified an E3 ligase, pre-mRNA processing factor 19 (Prpf19/prp19), that modulates expanded ataxin-3 (ATXN3-polyQ), disease protein of SCA3, induced neurodegeneration in both mammalian and Drosophila disease models. We further showed that Prpf19/prp19 promotes poly-ubiquitination and degradation of mutant ATXN3-polyQ protein. Our data further demonstrated the nuclear localization of Prpf19/prp19 is essential for eliciting its modulatory function towards toxic ATXN3-polyQ protein. Intriguingly, we found that exocyst complex component 7 (Exoc7/exo70), a Prpf19/prp19 interacting partner, modulates expanded ATXN3-polyQ protein levels and toxicity in an opposite manner to Prpf19/prp19. Our data suggest that Exoc7/exo70 exerts its ATXN3-polyQ-modifying effect through regulating the E3 ligase function of Prpf19/prp19. In summary, this study allows us to better define the mechanistic role of Exoc7/exo70-regulated Prpf19/prp19-associated protein ubiquitination pathway in SCA3 pathogenesis.

scholarly journals Homozygous spinocerebellar ataxia type 3 in China: a case report

2021 ◽  
Vol 49 (6) ◽  
pp. 030006052110213
Author(s):  
Yuchao Chen ◽  
Dan Li ◽  
Minger Wei ◽  
Menglu Zhou ◽  
Linan Zhang ◽  
...  
Keyword(s):  
Spinocerebellar Ataxia ◽  
Clinical Phenotype ◽  
Gene Dosage ◽  
Cag Repeat ◽  
Cag Repeats ◽  
Spinocerebellar Ataxia Type ◽  
Contraction Pattern ◽  
Spinocerebellar Ataxia Type 3 ◽  
Type 3 ◽  
Stable Transmission

Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disease caused by a heterozygous CAG repeat expansion in the ataxin 3 gene ( ATXN3). However, patients with homozygous SCA3 carrying expanded CAG repeats in both alleles of ATXN3 are extremely rare. Herein, we present a case of a 50-year-old female who had homozygous SCA3 with expansion of 62/62 repeats. Segregation analysis of the patient’s family showed both a contraction pattern of CAG repeat length and stable transmission. The present case demonstrated an earlier onset and more severe clinical phenotype than that seen in heterozygous individuals, suggesting that the gene dosage enhances disease severity.

scholarly journals Dystonia in Patients with Spinocerebellar Ataxia 3 - Machado-Joseph disease: An Underestimated Diagnosis?

2018 ◽  
Vol 12 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Ligia Maria Perrucci Catai ◽  
Carlos Henrique Ferreira Camargo ◽  
Adriana Moro ◽  
Gustavo Ribas ◽  
Salmo Raskin ◽  
...  
Keyword(s):  
Spinocerebellar Ataxia ◽  
Movement Disorders ◽  
Disease Onset ◽  
Cag Repeat ◽  
Spinocerebellar Ataxia Type ◽  
Spinocerebellar Ataxia Type 3 ◽  
Generalized Dystonia ◽  
Machado Joseph Disease ◽  
Sca3 Patient ◽  
Type 3

Background:Spinocerebellar Ataxia type 3 (SCA3) or Machado-Joseph Disease (MJD) is characterized by cerebellar, central and peripheral symptoms, including movement disorders. Dystonia can be classified as hereditary and neurodegenerative when present in SCA3.Objective:The objective of this study was to evaluate the dystonia characteristics in patients with MJD.Method:We identified all SCA3 patients with dystonia from the SCA3 HC-UFPR database, between December 2015 and December 2016.Their medical records were reviewed to verify the diagnosis of dystonia and obtain demographic and clinical data. Standardized evaluation was carried out through the classification of Movement Disorders Society of 2013 and Burke Fahn-Marsden scale (BFM).Results:Amongst the presenting some common characteristics, 381 patients with SCA3, 14 (3.7%) subjects presented dystonia: 5 blepharospasm, 1 cervical dystonia, 3 oromandibular, 3 multifocal and 2 generalized dystonia. Regarding dystonia's subtypes, 71.4% had SCA3 subtype I and 28.6% SCA3 subtype II. The average age of the disease onset was 40±10.7 years; the SCA3 disease duration was 11.86± 6.13 years; the CAG repeat lengths ranged from 75 to 78, and the BFM scores ranged from 1.0 to 40. There was no correlation between the dystonia severity and CAG repeat lengths or the SCA3 clinical evolution.Conclusion:Dystonia in SCA3 is frequent and displays highly variable clinical profiles and severity grades. Dystonia is therefore a present symptom in SCA3, which may precede the SCA3 classic symptoms. Dystonia diagnosis is yet to be properly recognized within SCA3 patient.

scholarly journals A Novel SCA3 Knock-in Mouse Model Mimics the Human SCA3 Disease Phenotype Including Neuropathological, Behavioral, and Transcriptional Abnormalities Especially in Oligodendrocytes

2021 ◽  
Author(s):  
Eva Haas ◽  
Rana D. Incebacak ◽  
Thomas Hentrich ◽  
Chrisovalantou Huridou ◽  
Thorsten Schmidt ◽  
...  
Keyword(s):  
Mouse Model ◽  
Brain Regions ◽  
Cag Repeat ◽  
Spinocerebellar Ataxia Type ◽  
The Novel ◽  
Spinocerebellar Ataxia Type 3 ◽  
Transcriptional Changes ◽  
Cerebellar Tissue ◽  
Type 3 ◽  
Polyq Expansion

AbstractSpinocerebellar ataxia type 3 is the most common autosomal dominant inherited ataxia worldwide, caused by a CAG repeat expansion in the Ataxin-3 gene resulting in a polyglutamine (polyQ)-expansion in the corresponding protein. The disease is characterized by neuropathological, phenotypical, and specific transcriptional changes in affected brain regions. So far, there is no mouse model available representing all the different aspects of the disease, yet highly needed for a better understanding of the disease pathomechanisms. Here, we characterized a novel Ataxin-3 knock-in mouse model, expressing a heterozygous or homozygous expansion of 304 CAACAGs in the murine Ataxin-3 locus using biochemical, behavioral, and transcriptomic approaches. We compared neuropathological, and behavioral features of the new knock-in model with the in SCA3 research mostly used YAC84Q mouse model. Further, we compared transcriptional changes found in cerebellar samples of the SCA3 knock-in mice and post-mortem human SCA3 patients. The novel knock-in mouse is characterized by the expression of a polyQ-expansion in the murine Ataxin-3 protein, leading to aggregate formation, especially in brain regions known to be vulnerable in SCA3 patients, and impairment of Purkinje cells. Along these neuropathological changes, the mice showed a reduction in body weight accompanied by gait and balance instability. Transcriptomic analysis of cerebellar tissue revealed age-dependent differential expression, enriched for genes attributed to myelinating oligodendrocytes. Comparing these changes with those found in cerebellar tissue of SCA3 patients, we discovered an overlap of differentially expressed genes pointing towards similar gene expression perturbances in several genes linked to myelin sheaths and myelinating oligodendrocytes.

scholarly journals Polyglutamine-expanded ataxin-3: a target engagement marker for Spinocerebellar ataxia type 3 in peripheral blood

2021 ◽  
Author(s):  
Jeannette Huebener-Schmid ◽  
Kirsten Kuhlbrodt ◽  
Julien Peladan ◽  
Jennifer Faber ◽  
Magda M Santana ◽  
...  
Keyword(s):  
Spinocerebellar Ataxia ◽  
Repeat Expansion ◽  
Cag Repeat ◽  
Spinocerebellar Ataxia Type ◽  
Clinical Parameters ◽  
Target Engagement ◽  
Spinocerebellar Ataxia Type 3 ◽  
Curative Therapy ◽  
Cag Repeat Expansion ◽  
Type 3

Abstract Spinocerebellar ataxia type 3 is a rare neurodegenerative disease, caused by a CAG repeat expansion leading to polyglutamine elongation in the ataxin-3 protein. While no curative therapy is yet available, preclinical gene silencing approaches to reduce polyglutamine-toxicity demonstrate promising results. In view of upcoming clinical trials, quantitative and easily accessible molecular markers are of critical importance as pharmacodynamic and particularly as target engagement markers. We developed a novel ultrasensitive immunoassay to measure specifically polyQ-expanded ataxin-3 in plasma and cerebrospinal fluid. Statistical analyses revealed a correlation with clinical parameters and a stability of polyglutamine-expanded ataxin-3 during conversion from the pre-ataxic to the ataxic phase.

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