DNAzyme Cleavage of CAG Repeat RNA in Polyglutamine Diseases

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.

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

Cell Death and Disease ◽

10.1038/s41419-021-03444-x ◽

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.

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Homozygous spinocerebellar ataxia type 3 in China: a case report

Journal of International Medical Research ◽

10.1177/03000605211021370 ◽

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.

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

The Open Neurology Journal ◽

10.2174/1874205x01812010041 ◽

2018 ◽

Vol 12 (1) ◽

pp. 41-49 ◽

Cited By ~ 2

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.

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Role of PICK1 in aggresome formation and spinocerebellar ataxia type 3 pathogenesis

10.14711/thesis-991012753766103412 ◽

2019 ◽

Author(s):

Ho Chun Lai

Keyword(s):

Spinocerebellar Ataxia ◽

Spinocerebellar Ataxia Type ◽

Spinocerebellar Ataxia Type 3 ◽

Aggresome Formation ◽

Type 3

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

Acta Biochimica Polonica ◽

10.18388/abp.2016_1336 ◽

2017 ◽

Vol 63 (4) ◽

Cited By ~ 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.

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

10.21203/rs.3.rs-384325/v1 ◽

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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Factors Associated with Intergenerational Instability of ATXN3 CAG Repeat and Genetic Anticipation in Chinese Patients with Spinocerebellar Ataxia Type 3

The Cerebellum ◽

10.1007/s12311-020-01167-x ◽

2020 ◽

Vol 19 (6) ◽

pp. 902-906

Author(s):

Yi-Chu Du ◽

Yin Ma ◽

Ya-Ru Shao ◽

Shi-Rui Gan ◽

Yi Dong ◽

...

Keyword(s):

Spinocerebellar Ataxia ◽

Cag Repeat ◽

Chinese Patients ◽

Spinocerebellar Ataxia Type ◽

Spinocerebellar Ataxia Type 3 ◽

Genetic Anticipation ◽

Factors Associated ◽

Type 3

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CAG repeat length does not associate with the rate of cerebellar degeneration in spinocerebellar ataxia type 3

NeuroImage Clinical ◽

10.1016/j.nicl.2016.11.007 ◽

2017 ◽

Vol 13 ◽

pp. 97-105 ◽

Cited By ~ 8

Author(s):

Shang-Ran Huang ◽

Yu-Te Wu ◽

Chii-Wen Jao ◽

Bing-Wen Soong ◽

Jiing-Feng Lirng ◽

...

Keyword(s):

Spinocerebellar Ataxia ◽

Cerebellar Degeneration ◽

Repeat Length ◽

Cag Repeat ◽

Spinocerebellar Ataxia Type ◽

Spinocerebellar Ataxia Type 3 ◽

Type 3

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Toward allele-specific targeting therapy and pharmacodynamic marker for spinocerebellar ataxia type 3

Science Translational Medicine ◽

10.1126/scitranslmed.abb7086 ◽

2020 ◽

Vol 12 (566) ◽

pp. eabb7086 ◽

Cited By ~ 1

Author(s):

Mercedes Prudencio ◽

Hector Garcia-Moreno ◽

Karen R. Jansen-West ◽

Rana Hanna AL-Shaikh ◽

Tania F. Gendron ◽

...

Keyword(s):

Clinical Trials ◽

Gene Silencing ◽

Spinocerebellar Ataxia ◽

Biological Fluids ◽

Human Fibroblasts ◽

Cag Repeat ◽

Spinocerebellar Ataxia Type ◽

Spinocerebellar Ataxia Type 3 ◽

Targeting Therapy ◽

Type 3

Spinocerebellar ataxia type 3 (SCA3), caused by a CAG repeat expansion in the ataxin-3 gene (ATXN3), is characterized by neuronal polyglutamine (polyQ) ATXN3 protein aggregates. Although there is no cure for SCA3, gene-silencing approaches to reduce toxic polyQ ATXN3 showed promise in preclinical models. However, a major limitation in translating putative treatments for this rare disease to the clinic is the lack of pharmacodynamic markers for use in clinical trials. Here, we developed an immunoassay that readily detects polyQ ATXN3 proteins in human biological fluids and discriminates patients with SCA3 from healthy controls and individuals with other ataxias. We show that polyQ ATXN3 serves as a marker of target engagement in human fibroblasts, which may bode well for its use in clinical trials. Last, we identified a single-nucleotide polymorphism that strongly associates with the expanded allele, thus providing an exciting drug target to abrogate detrimental events initiated by mutant ATXN3. Gene-silencing strategies for several repeat diseases are well under way, and our results are expected to improve clinical trial preparedness for SCA3 therapies.

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