RARE DISEASE
Spinocerebellar ataxia type 2
Spinocerebellar ataxia type 2
Spinocerebellar ataxia type 2
Synonyms: SCA2
Synonyms: SCA2
Synonyms: SCA2
Drug discovery
379
papers
On emerging therapies
Overview
Spinocerebellar Ataxia Type 2 (SCA2) is an autosomal dominant neurodegenerative disorder caused by CAG repeat expansions (≥33) in the ATXN2 gene. It presents with progressive cerebellar ataxia, slow saccades, peripheral neuropathy, and variable features including parkinsonism or cognitive decline [1][2][6]. Onset typically occurs in the 3rd–4th decade (range: 2–65 years), with motor disability progressing to wheelchair dependence within 12–25 years [4][6][7]. Neuropathology involves olivopontocerebellar atrophy and Purkinje cell dysfunction linked to disrupted calcium homeostasis [1][8].
Therapies
Symptomatic management: Neurorehabilitation programs improve coordination/stability [3], zinc sulfate (+8% SARA improvement) [3][14], and dopaminergic agents for parkinsonism [3]
Experimental approaches: Antisense oligonucleotides (ASOs) restored Purkinje cell firing in mice [3][8], calcium stabilizers (efonidipine) reversed cerebellar deficits in preclinical models [8][13]
Palliative care: Adaptive devices, dysphagia management, and genetic counseling [4][7]
Categories: rare genetic diseases, rare neurological diseases, rare ophthalmic disorders
Research Papers
379 drug discovery papers about Spinocerebellar ataxia type 2, with 4 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
379 drug discovery papers about Spinocerebellar ataxia type 2, with 4 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2026-09-23 | Neuroprotection Across Cerebellar and Nigrostriatal Degeneration: Translational Insights from Parkinson's Disease to Spinocerebellar Ataxia Type 2.
Spinocerebellar ataxia type 2 (SCA2) and Parkinson's disease (PD) have traditionally been conceptualized as distinct neurodegenerative movement disorders involving cerebellar and nigrostriatal circuits, respectively. However, increasing clinical, neuroimaging, and neuropathological evidence supports some commonneurodegenerative mechanisms. In PD, beyond dopaminergic degeneration, alterations in cerebellar structure and function contribute to both motor and non-motor manifestations, highlighting the functional integration between basal ganglia and cerebellar networks. At the molecular level, both disorders converge on common pathogenic mechanisms, including mitochondrial dysfunction, oxidative stress, impaired proteostasis, calcium dysregulation, and neuroinflammation. These shared pathways provide a strong rationale for developing neuroprotective strategies that extend beyond disease-specific targets. Nevertheless, despite extensive research, disease-modifying therapies remain elusive, particularly due to the complexity of neurodegenerative processes, clinical heterogeneity, and the lack of sensitive biomarkers for early disease stages. Insights derived from PD research indicate that single-target approaches are insufficient to halt disease progression, supporting the emergence of multi-target and systems-based therapeutic strategies. Within this framework, spinocerebellar ataxias, mainly SCA2 should be reconsidered as part of a broader spectrum of network neurodegeneration, in which cerebellar and extrapyramidal systems are dynamically interconnected. Overall, this integrative perspective highlights the importance of early intervention, biomarker-driven clinical trial design, and the development of therapies targeting convergent pathogenic mechanisms. Such an approach may ultimately enable the identification of effective disease-modifying strategies for SCA2 and related neurodegenerative disorders.
2026-07-10 | Immune Activation and Glial Dysfunction in Spinocerebellar Ataxias: From Cerebellar Landscape to Disease-Driven Mechanisms and Immunomodulation.
Spinocerebellar ataxias (SCAs) comprise a clinically and genetically heterogeneous group of autosomal dominant neurodegenerative disorders. Despite the recognized role of specialized cerebellar glia in cerebellar development and dysfunction, immune activation and non-immune glial responses remain understudied in SCAs. This narrative review compiles evidence from cellular, animal, and human models on the cerebellar immune landscape and the specific pathways that drive homeostatic failure and neuroinflammatory cascades across SCA subtypes. Microgliosis emerges consistently-and often early- as a generalized feature across the SCA spectrum, preceding neurodegeneration in several subtypes. Concurrently, reactive astrogliosis extends broadly, reflecting widespread macroglial surveillance and metabolic stress regulation throughout histologically preserved gray matter, with specialized homeostatic failure of Bergmann glia in SCA1, SCA2, and SCA7. Peripheral inflammation, manifests as early as the prodromal stage and correlates with the cognitive-affective deficits in SCA2 and associates with the mutation size in SCA3, positioning it as integral to pathogenesis rather than epiphenomenal. Diverse, partially shared signaling pathways converge on multi-lineage glial breakdown and reciprocal neuroimmune crosstalk. These mechanisms involve NF-κB (SCA1,3,17), cGAS-STING (SCA2), TLR/MyD88 (SCA6), and JNK/c-Jun (SCA1,2,7). This review establishes abnormal reciprocal immune/non-immune glia crosstalk as a core pathogenic principle across SCAs, revealing novel therapeutic opportunities. In fact, targeting convergent signaling nodes such as NF-κB, or JNK pathways, holds disease-modifying potential across multiple subtypes. Future research should prioritize standardized comparative studies, longitudinal analyses linking both inflammation and non-immune glial pathology to clinical progression, and clinical trials evaluating targeted immunomodulatory and glial homeostatic-supportive agents.
2026-05-28 | Aromatic-Turmerone Analogs Activate Chaperone-Mediated Autophagy and Ameliorate Dendritic Shrinkage in Purkinje Cell Models of Spinocerebellar Ataxia.
We recently demonstrated that aromatic (ar)-turmerone analogs ((E)-5-methyl-1-(p-tolyl)hexa-1,4-dien-3-one [A2] and (E)-1-(4-methoxyphenyl)-5-methylhexa-1,4-dien-3-one [A4]) activate chaperone-mediated autophagy (CMA), a pathway in the autophagy-lysosome protein degradation system, in SH-SY5Y cells. Our previous studies revealed that the impairment of CMA and microautophagy (mA), another autophagy-related pathway, and dendritic shrinkage were observed in primary cultured Purkinje cells (PCs) expressing causal proteins of spinocerebellar ataxia (SCA), an autosomal dominant neurodegenerative disease. In the present study, we first investigated the effects of A2 and A4 on lysosomal protein degradation and dendritic morphology in cerebellar primary cultured PCs. Both compounds enhanced dendritic development and activated CMA in cultured PCs. These effects were significantly suppressed by the inhibitors of nuclear factor erythroid 2-related factor 2 and p38. We next examined the effects of A2 and A4 on PCs expressing several types of SCA-causing proteins (SCA model PCs). Both chemicals ameliorated the dendritic shrinkage and restored the decreased CMA/mA activity in several SCA model PCs. These findings suggest that the ar-turmerone analogs A2 and A4 improve the in vitro phenotype of SCA model PCs through CMA activation, highlighting the therapeutic potential of these analogs for various types of SCAs.
2026-05-04 | Unraveling the Pathophysiological Link Between ALS and SCA: The Role of Ischemic Cerebral Vascular Dissection and the Efficacy of Endovascular Therapy.
To explore the role of ischemic cryptogenic vascular dissection (CVD) in a patient presenting with overlapping symptoms of amyotrophic lateral sclerosis (ALS) and spinocerebellar ataxia (SCA), and the impact of endovascular treatment on posterior circulation hypoperfusion, cerebellar atrophy, and clinical symptoms. A 22-year-old male patient with progressive neurological symptoms underwent MRI, CTA, and genetic testing, revealing cerebellar atrophy, a novel TGM6 gene variation associated with SCA type 35, and SETX gene deletions linked to ALS type 4. Ischemic CVD was diagnosed via dynamic contrast-enhanced CT (DCE-CT) and treated with endovascular stent repair followed by dual antiplatelet therapy. Following endovascular treatment, posterior circulation hypoperfusion and cerebellar atrophy were significantly improved. MRI follow-up showed increased cerebellar size and reduced interlobar spacing, with cerebellar dimensions expanding by up to 26.98% and interlobar spacing narrowing by up to 27.14%. Concurrently, the patient experienced marked improvement in clinical symptoms. At the 21-month follow-up, the patient's Modified Rankin Scale (MRS) score was rated as favorable. Ischemic CVD may underlie overlapping ALS and SCA symptoms, suggesting a genetic-vascular link. Endovascular treatment of CVD led to improvements in posterior circulation hypoperfusion, cerebellar atrophy, and clinical symptoms, supporting further investigation into this potential pathogenic nexus.
2026-04-24 | Developmental roots of cerebellar degeneration in spinocerebellar ataxia.
Late-onset neurodegenerative diseases have long been conceptualized as disorders arising from cumulative cellular stress and age-related decline, with pathology emerging at the time of symptom onset. However, emerging evidence challenges this view, suggesting that developmental perturbations may establish early vulnerabilities that predispose specific neuronal populations to degeneration later in life. In the cerebellum, mutations causing spinocerebellar ataxias (SCAs) such as SCA1 and SCA6 affect genes involved in normal circuit formation, resulting in subtle early abnormalities in Purkinje cell activity and connectivity. These alterations seem to be initially buffered by compensatory mechanisms, and the eventual breakdown of homeostatic resilience during midlife may thus be the trigger for disease onset and progression. This developmental perspective reframes late-onset neurodegeneration as a lifelong process shaped by the interplay between early developmental wiring, adaptive compensation, and age-dependent vulnerability. Understanding these early developmental alterations provides critical insight into disease mechanisms and opens new avenues for pre-symptomatic intervention and prevention.
gene therapies
2026-09-09 | MicroRNAs in polyglutamine diseases: Mechanistic insights, circulating biomarkers, and emerging microRNA-based therapeutic strategies.
MicroRNAs (miRNAs) have emerged as critical regulators in the pathogenesis of polyglutamine (PolyQ) diseases-a group of fatal neurodegenerative disorders caused by CAG repeat expansions, such as Huntington's disease, spinocerebellar ataxias, dentatorubral-pallidoluysian atrophy, and spinal and bulbar muscular atrophy. This review synthesizes recent advances in miRNA dysregulation across all nine PolyQ diseases, focusing on studies published since 2019. We examine how specific miRNAs modulate core pathogenic cascades-including mutant protein aggregation, transcriptional dysregulation, mitochondrial dysfunction, and apoptosis-and then link these molecular events to disease-relevant motor, cognitive, and psychiatric phenotypes. The review highlights therapeutic progress, including the preclinical efficacy of adeno-associated virus (AAV)-delivered artificial miRNAs and emerging exosome-based platforms that target mutant transcripts such as HTT, ATXN1, ATXN3, and ATXN7. AAV5-miHTT has advanced to a first-in-human trial for Huntington's disease (NCT04120493)-a key milestone in clinical translation. Circulating miRNAs in plasma and cerebrospinal fluid show diagnostic potential as minimally invasive, stage-specific biomarkers, but challenges persist in normalization, cross-biofluid concordance, and clinical validation. Despite substantial progress, translational barriers remain-including off-target effects, delivery optimization, immunogenicity, and patient heterogeneity. Overcoming these barriers will require integrative approaches that combine single-cell transcriptomics, engineered delivery systems, machine learning, and longitudinally phenotyped clinical cohorts. This review integrates mechanistic insights, biomarker discovery, and therapeutic development to move miRNA-based strategies toward disease-modifying interventions for PolyQ disorders.
2026-07-19 | Beyond the brain: Polyglutamine disease pathology outside the nervous system.
Polyglutamine diseases are primarily age-dependent neurodegenerative disorders, but patient-based data also point to a broader, multisystem biology. Clinical, imaging, biochemical, and post-mortem studies support peripheral involvement across multiple organ systems in the onset and progression of Huntington's Disease, Spinal and Bulbar Muscular Atrophy, Dentatorubral-Pallidoluysian Atrophy, and six Spinocerebellar Ataxias. Various peripheral abnormalities often emerge before or alongside overt neurological symptoms, contribute to disability and mortality, and are only partly explained by deconditioning or medications. Current data support viewing polyglutamine diseases as systemic protein-misfolding syndromes with organ-selective vulnerability, where peripheral tissues both mirror and modify CNS pathology in humans. Here, we propose that integrated, longitudinal, multisystem phenotyping and targeted organ-directed interventions are essential components of future research investigations, clinical care, and trial design.
2026-07-09 | Gene therapy for spinocerebellar ataxias.
Spinocerebellar ataxias (SCAs), rare neurodegenerative disorders characterized by progressive cerebellar degeneration, cause impaired balance and motor dysfunction. Although most cases are inherited, sporadic forms also occur, and effective disease-modifying therapies remain unavailable despite advances in understanding their genetic and molecular mechanisms. This unmet need is particularly significant because many SCAs are monogenic disorders caused by well-characterized mutations, making them promising candidates for gene- and RNA-based therapies. Recent advances in antisense oligonucleotides, RNA interference, vector engineering, and genome editing have increasingly enabled the alignment of therapeutic strategies with specific mutational architectures. Therefore, this review aims to examine how genetic subclassification informs platform selection, summarize recent advances in gene- and RNA-based therapeutics, and outline key translational barriers to clinical implementation in SCAs.
2026-04-30 | Management of spinocerebellar ataxia.
Spinocerebellar ataxias (SCAs) are a group of neurodegenerative diseases characterized by progressive cerebellar dysfunction, which leads to impaired coordination, dysarthria, oculomotor disorders, and subsequently to a marked reduction in quality of life and high disability. In addition to the main motor symptoms, patients often suffer from cerebellar cognitive-affective syndrome, depression, and sleep disturbances. Despite advances in understanding the molecular and genetic underpinnings of SCAs, there are currently no disease-modifying therapies approved by the FDA (U.S. Food and Drug Administration) or EMA (European Medicines Agency), and management remains largely symptomatic, focusing on improving quality of life and functional independence. Recent systematic reviews and clinical guidelines emphasize a combination of pharmacological, non-pharmacological, and novel gene and cell therapies that are currently under investigation, with varying levels of evidence for their efficacy. The transition to precision medicine and early intervention at the pre-ataxic stage are essential for effectively combating neurodegeneration. This review summarizes the latest data on the treatment of SCA, including existing and new treatments, their effectiveness, limitations, and future prospects.
2025-11-22 | Development of a Gene Therapy with Lentiviral Vectors for Spinocerebellar Ataxias.
Among viral vectors, lentiviral vectors allow an efficient delivery of nucleic acid to the target cells due to its ability of gene integration into host genome and broad tropism. In this sense, this tool demonstrated to be very promising in genetic disorders, such as polyglutamine spinocerebellar ataxias. Therefore, we describe a protocol that explains in detail the production, purification, and injection of lentiviral vectors in a spinocerebellar ataxia mouse model.
proteins
2026-03-12 | Retrotransposition Events Shape the Evolution of the Ataxin-3 Gene Family in Primates.
Evolutionary studies of disease-associated genes provide crucial insights into pathological mechanisms and potential therapeutic targets. Polyglutamine spinocerebellar ataxias (SCAs) are human neurodegenerative diseases caused by toxic expanded CAG repeats. Studies on SCA1 have shown that a paralog of the causing-gene can partially rescue protein function and alleviate the neuropathology. The most common SCA, Machado-Joseph disease (MJD/SCA3), caused by mutated ataxin-3 gene (ATXN3), has no treatment currently available. Its paralog ataxin-3 like (ATXN3L) remains largely unexplored. Here, we identify three new retrotransposition events of ATXN3: ATXN3L0 in Euarchontoglires, ATXN3L2 in Simiformes, and ATXN3L3 in Cercopithecidae, in addition to ATXN3L (herein called ATXN3L1) originated in Haplorrhini. ATXN3 and ATXN3L1 are both under purifying selection throughout primate evolution, maintaining about 70% of amino acid identity. Also, the high conservation of ATXN3L1 Josephin domain hints at functional redundancy with the parental disease-associated ATXN3. ATXN3L2 presents a remarkable nucleotide similarity to ATXN3 (79%) in an interrupted reading frame, which may produce a regulatory RNA. Conversely, ATXN3L0 is likely a non-functional retrocopy and ATXN3L3 is absent in humans with no relevance for the disease. The comparison of (CAG)n interruption patterns of the different paralogs in several primates elucidates the process leading to the currently observed pure long tracts in human ATXN3, responsible for disease when expanded. This study intends to pioneer the identification of new paralogs of SCA-associated genes and the use of phylogenetic analyses to explore their potential role for targeted therapies.
2026-02-19 | The Hsp40 cochaperone DNAJC7 regulates polyglutamine aggregation and exhibits context-dependent effects on polyglycine aggregation.
Protein-encoding nucleotide repeat expansion diseases, including polyglutamine (polyQ) and polyglycine (polyG) diseases, are characterized by the accumulation of aggregation-prone proteins. In the polyQ diseases, including Huntington's disease and several spinocerebellar ataxias, substantial prior evidence supports a pathogenic role for mutant polyQ-expanded protein misfolding and aggregation, with molecular chaperones showing promise in suppressing disease phenotypes in cellular and animal models. The goal of this study is to establish a scalable cell-based model to systematically evaluate genetic modifiers of protein aggregation in both polyQ and polyG diseases. We developed FRET-based reporter systems that model polyQ and polyG aggregation in human cells and used them to perform high-throughput CRISPR interference screens targeting all known molecular chaperones. In the polyQ model, the screen identified multiple Hsp70 chaperones and Hsp40 cochaperones previously implicated in polyQ aggregation and additionally revealed the Hsp40 cochaperone DNAJC7 as a potent and previously unrecognized suppressor of polyQ aggregation. In contrast, in a FRET-based polyG aggregation model of neuronal intranuclear inclusion disease, CRISPR interference screening showed minimal overlap of chaperone modifiers of the polyQ screen. Direct knockdown of DNAJC7 also did not affect polyG aggregation, yet overexpressed DNAJC7 colocalized with both polyQ and polyG aggregates in cells and reduced their aggregation. In addition to establishing new inducible, scalable cellular models for polyQ and polyG aggregation, this work expands the role of DNAJC7 in regulating the folding of disease-associated proteins.
2025-12-30 | Investigation of the stability of the polyQ tract in the ATXN2 gene in the presence of CAA-interruptions depending on the viscosity of the external
The ATXN2 gene plays a key role in the pathogenesis of neurodegenerative diseas-es such as spinocerebellar ataxia type 2 (SCA2). Expansion of trinucleotide repeats in the gene results in the formation of an abnormal protein with an extended polyglutamine strand, which is toxic to neurons and leads to their death. This disrupts the functioning of the cerebellum and other central nervous system structures, resulting in progressive deterioration of motor coordination and other neurological symptoms. Understanding the molecular basis of neurodegenerative processes caused by mutations in the ATXN2 gene, as well as the influence of environmental factors on disease development, remains an open question. Therefore, the aim of this study was to investigate the influence of the environment on the stability of the polyglutamine tract (polyQ) in the ATXN2 gene in the presence of a CAA interruption. The calculations were performed using an angular model of DNA, which considers the molecule as a system of interconnected pendulums, allow-ing for the influence of environmental viscosity on the dynamics of open states (OS) in DNA. The study was conducted at various viscosity values (λ = 0.9; 1.0; 1.1) and CAG tract lengths (from 35 to 55 repeats). The results showed that medium viscosity has a significant impact on polyQ tract stability, especially for CAG repeat lengths greater than 40. An increase in viscosity (λ = 1.1) contributed to a decrease in the number of additional OS zones, indicating its stabilizing role. Conversely, a decrease in viscosity (λ = 0.9) increased the likelihood of OS formation, exacerbating tract instability. It was established that CAA insertions in the polyQ tract influence the formation of additional OS zones and CAG tract stability depending on their location. The results of this study provide a pre-requisite for understanding the mechanisms regulating the structural stability of proteins associated with neurodegenerative diseases. The findings may lead to the development of more effective therapeutic strategies aimed at stabilizing abnormal polyQ tracts, poten-tially slowing the progression of diseases such as spinocerebellar ataxia and other pol-yglutamine pathologies.
2025-08-20 | The Hsp40 co-chaperone DNAJC7 modifies polyglutamine but not polyglycine aggregation.
Polyglutamine (polyQ) diseases, including Huntington's disease and several spinocerebellar ataxias, are caused by abnormally expanded CAG nucleotide repeats, which encode aggregation-prone polyQ tracts. Substantial prior evidence supports a pathogenic role for polyQ protein misfolding and aggregation, with molecular chaperones showing promise in suppressing disease phenotypes in cellular and animal models. In this study, we developed a FRET-based reporter system that models polyQ aggregation in human cells and used it to perform a high-throughput CRISPR interference screen targeting all known molecular chaperones. This screen identified as a strong suppressor of polyQ aggregation the Hsp40 co-chaperone DNAJC7, which has previously been shown to modify aggregation of other disease proteins (tau and TDP-43) and has mutations causative for amyotrophic lateral sclerosis. We validated this phenotype and further established a physical interaction between DNAJC7 and polyQ-expanded protein. In contrast, DNAJC7 did not modify aggregation of polyglycine (polyG) in a FRET-based model of neuronal intranuclear inclusion disease. In addition to establishing new inducible, scalable cellular models for polyQ and polyG aggregation, this work expands the role of DNAJC7 in regulating folding of disease-associated proteins.
2024-12-27 | Genetic modeling of degenerative diseases and mechanisms of neuronal regeneration in the zebrafish cerebellum.
The cerebellum is a highly conserved brain compartment of vertebrates. Genetic diseases of the human cerebellum often lead to degeneration of the principal neuron, the Purkinje cell, resulting in locomotive deficits and socio-emotional impairments. Due to its relatively simple but highly conserved neuroanatomy and circuitry, these human diseases can be modeled well in vertebrates amenable for genetic manipulation. In the recent years, cerebellar research in zebrafish has contributed to understanding cerebellum development and function, since zebrafish larvae are not only molecularly tractable, but also accessible for high resolution in vivo imaging due to the transparency of the larvae and the ease of access to the zebrafish cerebellar cortex for microscopy approaches. Therefore, zebrafish is increasingly used for genetic modeling of human cerebellar neurodegenerative diseases and in particular of different types of Spinocerebellar Ataxias (SCAs). These models are well suited to address the underlying pathogenic mechanisms by means of in vivo cell biological studies. Furthermore, accompanying circuitry characterizations, physiological studies and behavioral analysis allow for unraveling molecular, structural and functional relationships. Moreover, unlike in mammals, zebrafish possess an astonishing ability to regenerate neuronal populations and their functional circuitry in the central nervous system including the cerebellum. Understanding the cellular and molecular processes of these regenerative processes could well serve to counteract acute and chronic loss of neurons in humans. Based on the high evolutionary conservation of the cerebellum these regeneration studies in zebrafish promise to open therapeutic avenues for counteracting cerebellar neuronal degeneration. The current review aims to provide an overview over currently existing genetic models of human cerebellar neurodegenerative diseases in zebrafish as well as neuroregeneration studies using the zebrafish cerebellum. Due to this solid foundation in cerebellar disease modeling and neuronal regeneration analysis, the zebrafish promises to become a popular model organism for both unraveling pathogenic mechanisms of human cerebellar diseases and providing entry points for therapeutic neuronal regeneration approaches.
oligonucleotides
2026-01-19 | An acyclic nucleic acid-modified siRNA targeting CAG expansions for polyglutamine disease treatment.
Polyglutamine (polyQ) diseases are inherited neurological disorders caused by an expansion of the cytosine-adenine-guanine (CAG) repeat in the causative genes. These include Huntington's disease, spinal and bulbar muscular atrophy (SBMA), and spinocerebellar ataxias (SCAs). Clinical trials have been conducted using nucleic acid therapeutics to silence the causative gene for these diseases, but none have been approved for use. Furthermore, while oligonucleotides targeting the CAG repeats are an attractive therapeutic option, concomitant silencing of the wild-type allele with normal CAG repeats can result in neuronal dysfunction. In this study, we developed an acyclic serinol nucleic acid (SNA)-modified small interfering RNA (siRNA) targeting CAG repeats. We also evaluated the safety and efficacy of the siRNA in different mouse models of polyQ diseases. Intracerebroventricularly administered siRNA was widely distributed throughout the central nervous system, where it selectively silenced the alleles encoding polyQ proteins without affecting their wild-type counterparts. Consequently, the intranuclear aggregation of polyQ proteins was reduced in mouse models of SBMA and SCA type 3. The siRNA attenuated neuromuscular degeneration and improved the lifespan and motor function of the SBMA mice. These findings suggest that SNA-modified siRNAs targeting CAG repeats represent a promising approach for treating polyQ diseases.
2026-01-12 | Bioinformatic Analyses of the Ataxin-2 Family Since Algae Emphasize Its Small Isoforms, Large Chimerisms, and the Importance of Human Exon 1B as Target of Therapies to Prevent Neurodegeneration
Polyglutamine expansion in Ataxin-2 (ATXN2) is responsible for rare, dominantly in-herited Spinocerebellar Ataxia type 2 (SCA2). Together with its paralog Ataxin-2-like (ATXN2L), both proteins received much interest since deletion of their yeast and fly orthologs alleviates TDP-43-triggered neurotoxicity in Amyotrophic Lateral Sclerosis models. Their typical structure across evolution combines LSm with LSm-Associated Domains and a PAM2 motif. To understand the physiological regulation and functions of Ataxin-2 homologs, the phylogenesis of sequences was analyzed. Human ATXN2 harbors multiple alternative start codons, e.g. from an intrinsically disordered se-quence (IDR) present since armadillo, or from the polyQ sequence that arose since amphibians, or from the LSm domain since primitive eukaryotes. Multiple smaller isoforms also exist across the C-terminus. Therapeutic knockdown of polyQ expansions in human ATXN2 should selectively target exon 1B. PolyQ repeats developed repeat-edly, usually framed and often interrupted by (poly)Pro, originally near PAM2. The LSmAD sequence appeared in algae as the characteristic Ataxin-2 feature with strong conservation. Frequently, Ataxin-2 has added domains, likely due to transcriptional readthrough of neighbor genes during cell stress. These chimerisms show enrichment of rRNA processing; nutrient store mobilization; membrane strengthening via lipid, protein, and glycosylated components; and cell protrusions. Thus, any mutation of Ataxin-2 has complex effects, also affecting membrane resilience.
2025-11-27 | Isotopic H/D Exchange in Hydrogen Bonds Between the Nitrogenous Bases of the CAG Repeat Tract Makes It Possible to Stabilize Its Expansion in the ATXN2 Gene.
Background: The isotopic composition of the body's internal environment can affect its functional state. Such effects are realized, among other things, by inserting deuterium atoms into hydrogen bonds between pairs of nitrogenous bases of DNA molecules and modifying their mechanical properties. Methods: This study uses a coarse-grained mathematical model of DNA. Results: It has been established that in a certain range of the magnitude of the torque, with the presence of a deuterium atom within it, stabilization of the CAG repeat tract is observed. In addition, it was found that, regardless of which base pair the deuterium atom falls into in the CAG repeat tract, its stability increases and the probability of hairpin formation decreases, which may interfere with the reading of genetic information from the site encoding glutamine. Conclusions: Single H/D substitutions in the CAG repeat tract of the ATXN2 gene increase its stability by reducing the formation of open states, regardless of the position of deuterium.
2025-10-28 | Targeting STAU1 prevents p53 apoptotic signaling in neurodegeneration.
Stress responses and neuronal death mediated by the p53 pathway play a central role in the progression of neurodegenerative disease, constituting a common target to extend neuronal function and survival. Interaction of p53 and its signaling network with RNA-binding proteins (RBPs) helps fine-tune its activation and the resulting cell fates. Preclinical therapeutics based on depletion of the RBP STAUFEN-1 (STAU1) protein successfully prevent neurodegeneration, however, the specific mechanisms are not fully understood. STAU1 is pathologically overabundant in multiple neurological disorders and contributes to neurodegeneration by exacerbating autophagy dysfunction, endoplasmic reticulum stress, and RNA-protein condensate accumulation. We previously showed that lowering STAU1 levels mitigates these disease-related features and prevents neuronal death in animal models of amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) and spinocerebellar ataxia type 2 (SCA2). Here, we show by combined transcriptomic and functional analyses that STAU1 reduction results in the inhibition of apoptosis through the p53 pathway. In both proliferating and post-mitotic cell types-human iPSC-derived neurons, mouse cortical neurons, SH-SY5Y cells, and fibroblasts-STAU1 reduction effectively prevented p53-mediated apoptosis and DNA damage induced by Nutlin-3 and etoposide. Further examination in C9orf72-expanded patient-derived fibroblasts and a C9orf72 mouse model of ALS/FTD, which exhibit baseline overabundance of STAU1 and activation of the p53 pathway, confirmed that STAU1 reduction also prevented p53-driven pro-apoptotic signaling. These findings establish STAU1 as a novel modulator of DNA damage and p53-dependent apoptosis, suggesting that targeting STAU1 could be a promising approach to prevent neurodegeneration in ALS/FTD.
2025-10-03 | A human Staufen1 BAC transgenic mouse exhibits abnormal autophagy and neurodegeneration across the central nervous system.
RNA-binding proteins (RBPs) play an essential role in development, normal functioning and human disease. Staufen1 (STAU1) is an RBP that regulates mRNA degradation and subcellular localization, and is part of the ATXN2 protein complex. Previously, we showed that STAU1 is overabundant in patient fibroblasts and in mouse models of Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and spinocerebellar ataxia type 2 (SCA2), where it is associated with impaired autophagic flux due to STAU1-mediated upregulation of mTOR translation. STAU1 overabundance and impaired autophagy cause accumulation of biomolecular condensates and abnormal unfolded protein response (UPR). We generated a mouse model expressing the entire human STAU1 gene (hSTAU1) in a bacterial artificial chromosome (BAC) construct. hSTAU1 in these mice was expressed in cerebral hemispheres, cerebellum and spinal cord, as well as cultured cortical neurons and cortical and spinal cord astrocytes and microglia. Expression of hSTAU1 caused dysregulated gene expression, abnormal autophagy, glial activation, and changes in neuronal marker proteins. All of these were significantly improved by reducing STAU1 abundance by RNAi, but exacerbated in BAC-STAU1 mice crossed with Prp-TDP-43(Q331K) transgenic mice. Similar results were also obtained in eye phenotypes in ALS- and SCA2-relevant fly models upon changing staufen-1 dosage. Despite the molecular changes, we observed no overt behavioral changes in mice up to 55 weeks of age, suggesting that STAU1 may function as an epistatic modifier of neuronal degeneration. The BAC-hSTAU1 mouse will be useful for developing therapies targeting the human STAU1 gene.
other
2026-07-11 | Safety and preliminary efficacy of autologous bone marrow-derived mesenchymal stem cell transplantation in hereditary cerebellar ataxia: phase I/IIa clinical trial.
Hereditary cerebellar ataxias (HCA) encompass a spectrum of pathological conditions affecting the cerebellum. Currently, there is growing interest in the potential role of mesenchymal stem cells (MSCs) as an investigational therapeutic approach for this condition. Hence, the objective of this single-center, open-label, phase I/IIa clinical trial was to assess the safety and exploratory clinical and biomarker changes following a single intrathecal injection of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) in HCA. Ten confirmed patients with HCA entered the study and underwent a single dose of (1 × 106 cells/kg BW) intrathecal transplantation of BM-MSCs at passage 3. During the follow-up, patients were evaluated four times (one month before the intervention (-1), months 1, 3, and 6). Assessments included safety evaluation, Scale for the Assessment and Rating of Ataxia (SARA), GAD 65-antibody, and specific cytokines in the patient's serum and cerebrospinal fluid (CSF) samples. No severe adverse effects were observed following the cell transplantation procedure. A decreasing trend in SARA score was observed, with a statistically significant difference at month 6 compared with baseline. Except for one patient, GAD-65 antibody levels remained within the normal range in all patients. In one patient with markedly elevated baseline GAD-65 titers, serum and CSF GAD-65 levels decreased from 814 IU/mL and 781 IU/mL, respectively, to values within the normal range after 3 months. Significant changes were observed in selected inflammatory biomarkers, including decreased serum IL-6 at month 3, decreased CSF TNF-alpha at months 1 and 3, and increased serum IL-10 during follow-up. CSF IL-6 did not show a significant decrease. The findings support the short-term safety and tolerability of a single intrathecal dose of autologous BM-MSCs in this small HCA cohort. The study provides preliminary signals of possible clinical and biomarker changes; however, efficacy cannot be established due to the uncontrolled design, small sample size, disease heterogeneity, and short follow-up. Larger randomized controlled trials are required to validate these exploratory findings. This clinical trial was registered with the Iranian Registry of Clinical Trials (ID: IRCT20160809029275N3).
2026-04-13 | Cell-Based Therapies for Spinocerebellar Degenerations: A Systematic Review of Human Clinical Evidence.
Spinocerebellar degenerations (SCDs) are progressive hereditary and selected sporadic cerebellar neurodegenerative disorders with limited disease-modifying options. Cell-based therapies particularly, mesenchymal stromal/stem cells (MSCs), neural stem/progenitor cells, olfactory ensheathing cells (OECs), cord blood mononuclear cells (CBMCs), and hematopoietic stem cell transplantation (HSCT) are biologically plausible candidates, but their clinical efficacy and safety remain uncertain. We searched MEDLINE/PubMed, Embase, Scopus, Web of Science, and Cochrane Library from inception to 10 October 2025 (no language restrictions). The OSF-registered protocol prespecified eligibility, outcomes, and design-specific risk-of-bias (RoB) tools, with harmonized overall RoB judgments. We included human interventional or observational reports of cell-based or cell-derived products in hereditary ataxias and selected cerebellar-predominant degenerative syndromes within the OPCA/MSA-C spectrum, and extracted clinical efficacy, safety, and follow-up. Of 603 records screened, 17 reports met the protocol-defined inclusion criteria (15 full texts; 2 abstracts; 2006–2025). Most were small, uncontrolled case series, predominantly from China. Cell types: MSCs (9/17), HSCT in ataxia-telangiectasia (3/17), OECs (3/17), and others (neural stem cells [NSCs], CBMCs; 2/17). Routes were intrathecal and/or intravenous for MSC/CBMC; OEC/NSC were intracerebral/intraspinal; HSCT was delivered intravenously. Primary follow-up was typically 1–6 months. Safety was generally acceptable for MSC/CBMC/OEC with no treatment-related deaths and mostly transient post-procedural symptoms; HSCT exhibited regimen-related toxicities consistent with conditioning intensity. Efficacy signals were modest and often transient: short-term International Cooperative Ataxia Rating Scale (ICARS) improvements were reported across multiple series. Cell-based therapies for SCDs show biological plausibility and generally reassuring short-term safety, but current human evidence, dominated by uncontrolled, high-bias studies does not establish efficacy or durability. Priority should shift to rigorously controlled trials, standardized good manufacturing practice (GMP)-characterized products, blinded centralized ratings, careful control of co-interventions, and objective biomarkers.
2026-04-02 | IL-17A rescues motor deficits in a mouse model of Spinocerebellar Ataxia Type 2
Abstract Motor performance and coordination deficits are hallmarks of spinocerebellar ataxias, yet effective disease-modifying therapies remain limited. Here, we investigate the expression of the interleukin 17 receptor subunit A (IL-17RA) in cerebellum and assess the therapeutic potential of its ligand in a mouse model for Spinocerebellar Ataxia Type 2 (SCA2). We found that IL-17RA is highly enriched in cerebellar molecular layer interneurons (MLIs), which provide inhibitory input to Purkinje neurons. In-vitro electrophysiological recordings revealed that symptomatic SCA2 mice exhibited increased spontaneous inhibitory synaptic input onto Purkinje neurons, which was normalized by IL-17A application to control levels. Concomitantly, IL-17A application restored Purkinje neuron firing, a parameter characteristically reduced in SCA2 mice. Behaviorally, intranasal administration of IL-17A restored motor performance of symptomatic SCA2 mice to control levels in both rotarod and beam-crossing assays. Collectively, our results indicate that IL-17A rescues Purkinje neuron dysfunction and motor deficits in SCA2 mice, highlighting IL-17A signaling as a promising therapeutic target for spinocerebellar ataxia.
2025-01-03 | Transcriptomic analysis of repeat expansion-ataxias uncovers distinct non-neuronal cell type-specific signatures of disease across the human brain
Abstract Hereditary ataxias are a heterogeneous group of neurogenetic conditions characterised by the clinical syndrome of progressive loss of coordination from neurodegeneration of the cerebellum. A commonality across the most prevalent ataxias is the underlying disease mechanism secondary to expansions of short tandem DNA repeats. There is currently an incomplete understanding of the pathogenic mechanisms of these repeat expansion disorders, a core feature of which revolves around RNA-dysregulation. In this study, we used both bulk and single nuclear RNA-sequencing to study post-mortem brain tissue of human donors with a range of repeat-expansion ataxias to reveal further mechanistic insights. We compared post-mortem paired cerebellar and frontal cortex tissue bulk RNA-sequencing data from 23 ataxia patients and 22 sex-, age-matched controls from two brain banks (spinocerebellar ataxia (SCA)1, SCA2, SCA6, SCA7, SCA17, Friedreich’s ataxia (FRDA), and 7 cases with unknown molecular diagnoses). We analysed bulk RNA-sequencing data for transcript usage, differential and cell-type-specific expression to transcriptomically profile these diseases. We also generated single nuclear RNA-sequencing data of the cerebellum from donors with SCA1, SCA2, SCA6 and FRDA to decipher changes in cell type proportions in the disease state. Using this approach, we found that: (i) despite the commonalities in the genetics of ataxia, there were components of their transcriptional signatures which were distinct; (ii) there were extensive transcriptional changes evident not only in the cerebellum but also the frontal cortex in ataxia cases; (iii) activation of immune and inflammatory pathways, as well as involvement of non-neuronal cell types was a feature of all ataxias to a lesser or greater extent. This study provides a novel resource to understand the mechanisms of disease in ataxia. Furthermore, taken together, these results highlight immune pathways and the role of non-neuronal cell types as early and potentially important therapeutic targets. These findings provide a map of transcriptomic changes in ataxia to further understanding of the underlying pathogenesis.
2024-11-13 | Post-symptomatic administration of hMSCs exerts therapeutic effects in SCA2 mice.
Defects in the ataxin-2 (ATXN-2) protein and CAG trinucleotide repeat expansion in its coding gene, Atxn-2, cause the neurodegenerative disorder spinocerebellar ataxia type 2 (SCA2). While clinical studies suggest potential benefits of human-derived mesenchymal stem cells (hMSCs) for treating various ataxias, the exact mechanisms underlying their therapeutic effects and interaction with host tissue to stimulate neurotrophin expression remain unclear specifically in the context of SCA2. Human bone marrow-derived MSCs (hMSCs) were injected into the cisterna magna of 26-week-old wild-type and SCA2 mice. Mice were assessed for impaired motor coordination using the accelerating rotarod, open field test, and composite phenotype scoring. At 50 weeks, the cerebellum vermis was harvested for protein assessment and immunohistochemical analysis. Significant loss of NeuN and calbindin was observed in 25-week-old SCA2 mice. However, after receiving multiple injections of hMSCs starting at 26 weeks of age, these mice exhibited a significant improvement in abnormal motor performance and a protective effect on Purkinje cells. This beneficial effect persisted until the mice reached 50 weeks of age, at which point they were sacrificed to study further mechanistic events triggered by the administration of hMSCs. Calbindin-positive cells in the Purkinje cell layer expressed bone-derived neurotrophic factor after hMSC administration, contributing to the protection of cerebellar neurons from cell death. In conclusion, repeated administration of hMSCs shows promise in alleviating SCA2 symptoms by preserving Purkinje cells, improving neurotrophic support, and reducing inflammation, ultimately leading to the preservation of locomotor function in SCA2 mice.
small molecules
2026-09-23 | Neuroprotection Across Cerebellar and Nigrostriatal Degeneration: Translational Insights from Parkinson's Disease to Spinocerebellar Ataxia Type 2.
Spinocerebellar ataxia type 2 (SCA2) and Parkinson's disease (PD) have traditionally been conceptualized as distinct neurodegenerative movement disorders involving cerebellar and nigrostriatal circuits, respectively. However, increasing clinical, neuroimaging, and neuropathological evidence supports some commonneurodegenerative mechanisms. In PD, beyond dopaminergic degeneration, alterations in cerebellar structure and function contribute to both motor and non-motor manifestations, highlighting the functional integration between basal ganglia and cerebellar networks. At the molecular level, both disorders converge on common pathogenic mechanisms, including mitochondrial dysfunction, oxidative stress, impaired proteostasis, calcium dysregulation, and neuroinflammation. These shared pathways provide a strong rationale for developing neuroprotective strategies that extend beyond disease-specific targets. Nevertheless, despite extensive research, disease-modifying therapies remain elusive, particularly due to the complexity of neurodegenerative processes, clinical heterogeneity, and the lack of sensitive biomarkers for early disease stages. Insights derived from PD research indicate that single-target approaches are insufficient to halt disease progression, supporting the emergence of multi-target and systems-based therapeutic strategies. Within this framework, spinocerebellar ataxias, mainly SCA2 should be reconsidered as part of a broader spectrum of network neurodegeneration, in which cerebellar and extrapyramidal systems are dynamically interconnected. Overall, this integrative perspective highlights the importance of early intervention, biomarker-driven clinical trial design, and the development of therapies targeting convergent pathogenic mechanisms. Such an approach may ultimately enable the identification of effective disease-modifying strategies for SCA2 and related neurodegenerative disorders.
2026-07-10 | Immune Activation and Glial Dysfunction in Spinocerebellar Ataxias: From Cerebellar Landscape to Disease-Driven Mechanisms and Immunomodulation.
Spinocerebellar ataxias (SCAs) comprise a clinically and genetically heterogeneous group of autosomal dominant neurodegenerative disorders. Despite the recognized role of specialized cerebellar glia in cerebellar development and dysfunction, immune activation and non-immune glial responses remain understudied in SCAs. This narrative review compiles evidence from cellular, animal, and human models on the cerebellar immune landscape and the specific pathways that drive homeostatic failure and neuroinflammatory cascades across SCA subtypes. Microgliosis emerges consistently-and often early- as a generalized feature across the SCA spectrum, preceding neurodegeneration in several subtypes. Concurrently, reactive astrogliosis extends broadly, reflecting widespread macroglial surveillance and metabolic stress regulation throughout histologically preserved gray matter, with specialized homeostatic failure of Bergmann glia in SCA1, SCA2, and SCA7. Peripheral inflammation, manifests as early as the prodromal stage and correlates with the cognitive-affective deficits in SCA2 and associates with the mutation size in SCA3, positioning it as integral to pathogenesis rather than epiphenomenal. Diverse, partially shared signaling pathways converge on multi-lineage glial breakdown and reciprocal neuroimmune crosstalk. These mechanisms involve NF-κB (SCA1,3,17), cGAS-STING (SCA2), TLR/MyD88 (SCA6), and JNK/c-Jun (SCA1,2,7). This review establishes abnormal reciprocal immune/non-immune glia crosstalk as a core pathogenic principle across SCAs, revealing novel therapeutic opportunities. In fact, targeting convergent signaling nodes such as NF-κB, or JNK pathways, holds disease-modifying potential across multiple subtypes. Future research should prioritize standardized comparative studies, longitudinal analyses linking both inflammation and non-immune glial pathology to clinical progression, and clinical trials evaluating targeted immunomodulatory and glial homeostatic-supportive agents.
2026-05-28 | Aromatic-Turmerone Analogs Activate Chaperone-Mediated Autophagy and Ameliorate Dendritic Shrinkage in Purkinje Cell Models of Spinocerebellar Ataxia.
We recently demonstrated that aromatic (ar)-turmerone analogs ((E)-5-methyl-1-(p-tolyl)hexa-1,4-dien-3-one [A2] and (E)-1-(4-methoxyphenyl)-5-methylhexa-1,4-dien-3-one [A4]) activate chaperone-mediated autophagy (CMA), a pathway in the autophagy-lysosome protein degradation system, in SH-SY5Y cells. Our previous studies revealed that the impairment of CMA and microautophagy (mA), another autophagy-related pathway, and dendritic shrinkage were observed in primary cultured Purkinje cells (PCs) expressing causal proteins of spinocerebellar ataxia (SCA), an autosomal dominant neurodegenerative disease. In the present study, we first investigated the effects of A2 and A4 on lysosomal protein degradation and dendritic morphology in cerebellar primary cultured PCs. Both compounds enhanced dendritic development and activated CMA in cultured PCs. These effects were significantly suppressed by the inhibitors of nuclear factor erythroid 2-related factor 2 and p38. We next examined the effects of A2 and A4 on PCs expressing several types of SCA-causing proteins (SCA model PCs). Both chemicals ameliorated the dendritic shrinkage and restored the decreased CMA/mA activity in several SCA model PCs. These findings suggest that the ar-turmerone analogs A2 and A4 improve the in vitro phenotype of SCA model PCs through CMA activation, highlighting the therapeutic potential of these analogs for various types of SCAs.
2026-05-04 | Unraveling the Pathophysiological Link Between ALS and SCA: The Role of Ischemic Cerebral Vascular Dissection and the Efficacy of Endovascular Therapy.
To explore the role of ischemic cryptogenic vascular dissection (CVD) in a patient presenting with overlapping symptoms of amyotrophic lateral sclerosis (ALS) and spinocerebellar ataxia (SCA), and the impact of endovascular treatment on posterior circulation hypoperfusion, cerebellar atrophy, and clinical symptoms. A 22-year-old male patient with progressive neurological symptoms underwent MRI, CTA, and genetic testing, revealing cerebellar atrophy, a novel TGM6 gene variation associated with SCA type 35, and SETX gene deletions linked to ALS type 4. Ischemic CVD was diagnosed via dynamic contrast-enhanced CT (DCE-CT) and treated with endovascular stent repair followed by dual antiplatelet therapy. Following endovascular treatment, posterior circulation hypoperfusion and cerebellar atrophy were significantly improved. MRI follow-up showed increased cerebellar size and reduced interlobar spacing, with cerebellar dimensions expanding by up to 26.98% and interlobar spacing narrowing by up to 27.14%. Concurrently, the patient experienced marked improvement in clinical symptoms. At the 21-month follow-up, the patient's Modified Rankin Scale (MRS) score was rated as favorable. Ischemic CVD may underlie overlapping ALS and SCA symptoms, suggesting a genetic-vascular link. Endovascular treatment of CVD led to improvements in posterior circulation hypoperfusion, cerebellar atrophy, and clinical symptoms, supporting further investigation into this potential pathogenic nexus.
2026-04-24 | Developmental roots of cerebellar degeneration in spinocerebellar ataxia.
Late-onset neurodegenerative diseases have long been conceptualized as disorders arising from cumulative cellular stress and age-related decline, with pathology emerging at the time of symptom onset. However, emerging evidence challenges this view, suggesting that developmental perturbations may establish early vulnerabilities that predispose specific neuronal populations to degeneration later in life. In the cerebellum, mutations causing spinocerebellar ataxias (SCAs) such as SCA1 and SCA6 affect genes involved in normal circuit formation, resulting in subtle early abnormalities in Purkinje cell activity and connectivity. These alterations seem to be initially buffered by compensatory mechanisms, and the eventual breakdown of homeostatic resilience during midlife may thus be the trigger for disease onset and progression. This developmental perspective reframes late-onset neurodegeneration as a lifelong process shaped by the interplay between early developmental wiring, adaptive compensation, and age-dependent vulnerability. Understanding these early developmental alterations provides critical insight into disease mechanisms and opens new avenues for pre-symptomatic intervention and prevention.
gene therapies
2026-09-09 | MicroRNAs in polyglutamine diseases: Mechanistic insights, circulating biomarkers, and emerging microRNA-based therapeutic strategies.
MicroRNAs (miRNAs) have emerged as critical regulators in the pathogenesis of polyglutamine (PolyQ) diseases-a group of fatal neurodegenerative disorders caused by CAG repeat expansions, such as Huntington's disease, spinocerebellar ataxias, dentatorubral-pallidoluysian atrophy, and spinal and bulbar muscular atrophy. This review synthesizes recent advances in miRNA dysregulation across all nine PolyQ diseases, focusing on studies published since 2019. We examine how specific miRNAs modulate core pathogenic cascades-including mutant protein aggregation, transcriptional dysregulation, mitochondrial dysfunction, and apoptosis-and then link these molecular events to disease-relevant motor, cognitive, and psychiatric phenotypes. The review highlights therapeutic progress, including the preclinical efficacy of adeno-associated virus (AAV)-delivered artificial miRNAs and emerging exosome-based platforms that target mutant transcripts such as HTT, ATXN1, ATXN3, and ATXN7. AAV5-miHTT has advanced to a first-in-human trial for Huntington's disease (NCT04120493)-a key milestone in clinical translation. Circulating miRNAs in plasma and cerebrospinal fluid show diagnostic potential as minimally invasive, stage-specific biomarkers, but challenges persist in normalization, cross-biofluid concordance, and clinical validation. Despite substantial progress, translational barriers remain-including off-target effects, delivery optimization, immunogenicity, and patient heterogeneity. Overcoming these barriers will require integrative approaches that combine single-cell transcriptomics, engineered delivery systems, machine learning, and longitudinally phenotyped clinical cohorts. This review integrates mechanistic insights, biomarker discovery, and therapeutic development to move miRNA-based strategies toward disease-modifying interventions for PolyQ disorders.
2026-07-19 | Beyond the brain: Polyglutamine disease pathology outside the nervous system.
Polyglutamine diseases are primarily age-dependent neurodegenerative disorders, but patient-based data also point to a broader, multisystem biology. Clinical, imaging, biochemical, and post-mortem studies support peripheral involvement across multiple organ systems in the onset and progression of Huntington's Disease, Spinal and Bulbar Muscular Atrophy, Dentatorubral-Pallidoluysian Atrophy, and six Spinocerebellar Ataxias. Various peripheral abnormalities often emerge before or alongside overt neurological symptoms, contribute to disability and mortality, and are only partly explained by deconditioning or medications. Current data support viewing polyglutamine diseases as systemic protein-misfolding syndromes with organ-selective vulnerability, where peripheral tissues both mirror and modify CNS pathology in humans. Here, we propose that integrated, longitudinal, multisystem phenotyping and targeted organ-directed interventions are essential components of future research investigations, clinical care, and trial design.
2026-07-09 | Gene therapy for spinocerebellar ataxias.
Spinocerebellar ataxias (SCAs), rare neurodegenerative disorders characterized by progressive cerebellar degeneration, cause impaired balance and motor dysfunction. Although most cases are inherited, sporadic forms also occur, and effective disease-modifying therapies remain unavailable despite advances in understanding their genetic and molecular mechanisms. This unmet need is particularly significant because many SCAs are monogenic disorders caused by well-characterized mutations, making them promising candidates for gene- and RNA-based therapies. Recent advances in antisense oligonucleotides, RNA interference, vector engineering, and genome editing have increasingly enabled the alignment of therapeutic strategies with specific mutational architectures. Therefore, this review aims to examine how genetic subclassification informs platform selection, summarize recent advances in gene- and RNA-based therapeutics, and outline key translational barriers to clinical implementation in SCAs.
2026-04-30 | Management of spinocerebellar ataxia.
Spinocerebellar ataxias (SCAs) are a group of neurodegenerative diseases characterized by progressive cerebellar dysfunction, which leads to impaired coordination, dysarthria, oculomotor disorders, and subsequently to a marked reduction in quality of life and high disability. In addition to the main motor symptoms, patients often suffer from cerebellar cognitive-affective syndrome, depression, and sleep disturbances. Despite advances in understanding the molecular and genetic underpinnings of SCAs, there are currently no disease-modifying therapies approved by the FDA (U.S. Food and Drug Administration) or EMA (European Medicines Agency), and management remains largely symptomatic, focusing on improving quality of life and functional independence. Recent systematic reviews and clinical guidelines emphasize a combination of pharmacological, non-pharmacological, and novel gene and cell therapies that are currently under investigation, with varying levels of evidence for their efficacy. The transition to precision medicine and early intervention at the pre-ataxic stage are essential for effectively combating neurodegeneration. This review summarizes the latest data on the treatment of SCA, including existing and new treatments, their effectiveness, limitations, and future prospects.
2025-11-22 | Development of a Gene Therapy with Lentiviral Vectors for Spinocerebellar Ataxias.
Among viral vectors, lentiviral vectors allow an efficient delivery of nucleic acid to the target cells due to its ability of gene integration into host genome and broad tropism. In this sense, this tool demonstrated to be very promising in genetic disorders, such as polyglutamine spinocerebellar ataxias. Therefore, we describe a protocol that explains in detail the production, purification, and injection of lentiviral vectors in a spinocerebellar ataxia mouse model.
proteins
2026-03-12 | Retrotransposition Events Shape the Evolution of the Ataxin-3 Gene Family in Primates.
Evolutionary studies of disease-associated genes provide crucial insights into pathological mechanisms and potential therapeutic targets. Polyglutamine spinocerebellar ataxias (SCAs) are human neurodegenerative diseases caused by toxic expanded CAG repeats. Studies on SCA1 have shown that a paralog of the causing-gene can partially rescue protein function and alleviate the neuropathology. The most common SCA, Machado-Joseph disease (MJD/SCA3), caused by mutated ataxin-3 gene (ATXN3), has no treatment currently available. Its paralog ataxin-3 like (ATXN3L) remains largely unexplored. Here, we identify three new retrotransposition events of ATXN3: ATXN3L0 in Euarchontoglires, ATXN3L2 in Simiformes, and ATXN3L3 in Cercopithecidae, in addition to ATXN3L (herein called ATXN3L1) originated in Haplorrhini. ATXN3 and ATXN3L1 are both under purifying selection throughout primate evolution, maintaining about 70% of amino acid identity. Also, the high conservation of ATXN3L1 Josephin domain hints at functional redundancy with the parental disease-associated ATXN3. ATXN3L2 presents a remarkable nucleotide similarity to ATXN3 (79%) in an interrupted reading frame, which may produce a regulatory RNA. Conversely, ATXN3L0 is likely a non-functional retrocopy and ATXN3L3 is absent in humans with no relevance for the disease. The comparison of (CAG)n interruption patterns of the different paralogs in several primates elucidates the process leading to the currently observed pure long tracts in human ATXN3, responsible for disease when expanded. This study intends to pioneer the identification of new paralogs of SCA-associated genes and the use of phylogenetic analyses to explore their potential role for targeted therapies.
2026-02-19 | The Hsp40 cochaperone DNAJC7 regulates polyglutamine aggregation and exhibits context-dependent effects on polyglycine aggregation.
Protein-encoding nucleotide repeat expansion diseases, including polyglutamine (polyQ) and polyglycine (polyG) diseases, are characterized by the accumulation of aggregation-prone proteins. In the polyQ diseases, including Huntington's disease and several spinocerebellar ataxias, substantial prior evidence supports a pathogenic role for mutant polyQ-expanded protein misfolding and aggregation, with molecular chaperones showing promise in suppressing disease phenotypes in cellular and animal models. The goal of this study is to establish a scalable cell-based model to systematically evaluate genetic modifiers of protein aggregation in both polyQ and polyG diseases. We developed FRET-based reporter systems that model polyQ and polyG aggregation in human cells and used them to perform high-throughput CRISPR interference screens targeting all known molecular chaperones. In the polyQ model, the screen identified multiple Hsp70 chaperones and Hsp40 cochaperones previously implicated in polyQ aggregation and additionally revealed the Hsp40 cochaperone DNAJC7 as a potent and previously unrecognized suppressor of polyQ aggregation. In contrast, in a FRET-based polyG aggregation model of neuronal intranuclear inclusion disease, CRISPR interference screening showed minimal overlap of chaperone modifiers of the polyQ screen. Direct knockdown of DNAJC7 also did not affect polyG aggregation, yet overexpressed DNAJC7 colocalized with both polyQ and polyG aggregates in cells and reduced their aggregation. In addition to establishing new inducible, scalable cellular models for polyQ and polyG aggregation, this work expands the role of DNAJC7 in regulating the folding of disease-associated proteins.
2025-12-30 | Investigation of the stability of the polyQ tract in the ATXN2 gene in the presence of CAA-interruptions depending on the viscosity of the external
The ATXN2 gene plays a key role in the pathogenesis of neurodegenerative diseas-es such as spinocerebellar ataxia type 2 (SCA2). Expansion of trinucleotide repeats in the gene results in the formation of an abnormal protein with an extended polyglutamine strand, which is toxic to neurons and leads to their death. This disrupts the functioning of the cerebellum and other central nervous system structures, resulting in progressive deterioration of motor coordination and other neurological symptoms. Understanding the molecular basis of neurodegenerative processes caused by mutations in the ATXN2 gene, as well as the influence of environmental factors on disease development, remains an open question. Therefore, the aim of this study was to investigate the influence of the environment on the stability of the polyglutamine tract (polyQ) in the ATXN2 gene in the presence of a CAA interruption. The calculations were performed using an angular model of DNA, which considers the molecule as a system of interconnected pendulums, allow-ing for the influence of environmental viscosity on the dynamics of open states (OS) in DNA. The study was conducted at various viscosity values (λ = 0.9; 1.0; 1.1) and CAG tract lengths (from 35 to 55 repeats). The results showed that medium viscosity has a significant impact on polyQ tract stability, especially for CAG repeat lengths greater than 40. An increase in viscosity (λ = 1.1) contributed to a decrease in the number of additional OS zones, indicating its stabilizing role. Conversely, a decrease in viscosity (λ = 0.9) increased the likelihood of OS formation, exacerbating tract instability. It was established that CAA insertions in the polyQ tract influence the formation of additional OS zones and CAG tract stability depending on their location. The results of this study provide a pre-requisite for understanding the mechanisms regulating the structural stability of proteins associated with neurodegenerative diseases. The findings may lead to the development of more effective therapeutic strategies aimed at stabilizing abnormal polyQ tracts, poten-tially slowing the progression of diseases such as spinocerebellar ataxia and other pol-yglutamine pathologies.
2025-08-20 | The Hsp40 co-chaperone DNAJC7 modifies polyglutamine but not polyglycine aggregation.
Polyglutamine (polyQ) diseases, including Huntington's disease and several spinocerebellar ataxias, are caused by abnormally expanded CAG nucleotide repeats, which encode aggregation-prone polyQ tracts. Substantial prior evidence supports a pathogenic role for polyQ protein misfolding and aggregation, with molecular chaperones showing promise in suppressing disease phenotypes in cellular and animal models. In this study, we developed a FRET-based reporter system that models polyQ aggregation in human cells and used it to perform a high-throughput CRISPR interference screen targeting all known molecular chaperones. This screen identified as a strong suppressor of polyQ aggregation the Hsp40 co-chaperone DNAJC7, which has previously been shown to modify aggregation of other disease proteins (tau and TDP-43) and has mutations causative for amyotrophic lateral sclerosis. We validated this phenotype and further established a physical interaction between DNAJC7 and polyQ-expanded protein. In contrast, DNAJC7 did not modify aggregation of polyglycine (polyG) in a FRET-based model of neuronal intranuclear inclusion disease. In addition to establishing new inducible, scalable cellular models for polyQ and polyG aggregation, this work expands the role of DNAJC7 in regulating folding of disease-associated proteins.
2024-12-27 | Genetic modeling of degenerative diseases and mechanisms of neuronal regeneration in the zebrafish cerebellum.
The cerebellum is a highly conserved brain compartment of vertebrates. Genetic diseases of the human cerebellum often lead to degeneration of the principal neuron, the Purkinje cell, resulting in locomotive deficits and socio-emotional impairments. Due to its relatively simple but highly conserved neuroanatomy and circuitry, these human diseases can be modeled well in vertebrates amenable for genetic manipulation. In the recent years, cerebellar research in zebrafish has contributed to understanding cerebellum development and function, since zebrafish larvae are not only molecularly tractable, but also accessible for high resolution in vivo imaging due to the transparency of the larvae and the ease of access to the zebrafish cerebellar cortex for microscopy approaches. Therefore, zebrafish is increasingly used for genetic modeling of human cerebellar neurodegenerative diseases and in particular of different types of Spinocerebellar Ataxias (SCAs). These models are well suited to address the underlying pathogenic mechanisms by means of in vivo cell biological studies. Furthermore, accompanying circuitry characterizations, physiological studies and behavioral analysis allow for unraveling molecular, structural and functional relationships. Moreover, unlike in mammals, zebrafish possess an astonishing ability to regenerate neuronal populations and their functional circuitry in the central nervous system including the cerebellum. Understanding the cellular and molecular processes of these regenerative processes could well serve to counteract acute and chronic loss of neurons in humans. Based on the high evolutionary conservation of the cerebellum these regeneration studies in zebrafish promise to open therapeutic avenues for counteracting cerebellar neuronal degeneration. The current review aims to provide an overview over currently existing genetic models of human cerebellar neurodegenerative diseases in zebrafish as well as neuroregeneration studies using the zebrafish cerebellum. Due to this solid foundation in cerebellar disease modeling and neuronal regeneration analysis, the zebrafish promises to become a popular model organism for both unraveling pathogenic mechanisms of human cerebellar diseases and providing entry points for therapeutic neuronal regeneration approaches.
oligonucleotides
2026-01-19 | An acyclic nucleic acid-modified siRNA targeting CAG expansions for polyglutamine disease treatment.
Polyglutamine (polyQ) diseases are inherited neurological disorders caused by an expansion of the cytosine-adenine-guanine (CAG) repeat in the causative genes. These include Huntington's disease, spinal and bulbar muscular atrophy (SBMA), and spinocerebellar ataxias (SCAs). Clinical trials have been conducted using nucleic acid therapeutics to silence the causative gene for these diseases, but none have been approved for use. Furthermore, while oligonucleotides targeting the CAG repeats are an attractive therapeutic option, concomitant silencing of the wild-type allele with normal CAG repeats can result in neuronal dysfunction. In this study, we developed an acyclic serinol nucleic acid (SNA)-modified small interfering RNA (siRNA) targeting CAG repeats. We also evaluated the safety and efficacy of the siRNA in different mouse models of polyQ diseases. Intracerebroventricularly administered siRNA was widely distributed throughout the central nervous system, where it selectively silenced the alleles encoding polyQ proteins without affecting their wild-type counterparts. Consequently, the intranuclear aggregation of polyQ proteins was reduced in mouse models of SBMA and SCA type 3. The siRNA attenuated neuromuscular degeneration and improved the lifespan and motor function of the SBMA mice. These findings suggest that SNA-modified siRNAs targeting CAG repeats represent a promising approach for treating polyQ diseases.
2026-01-12 | Bioinformatic Analyses of the Ataxin-2 Family Since Algae Emphasize Its Small Isoforms, Large Chimerisms, and the Importance of Human Exon 1B as Target of Therapies to Prevent Neurodegeneration
Polyglutamine expansion in Ataxin-2 (ATXN2) is responsible for rare, dominantly in-herited Spinocerebellar Ataxia type 2 (SCA2). Together with its paralog Ataxin-2-like (ATXN2L), both proteins received much interest since deletion of their yeast and fly orthologs alleviates TDP-43-triggered neurotoxicity in Amyotrophic Lateral Sclerosis models. Their typical structure across evolution combines LSm with LSm-Associated Domains and a PAM2 motif. To understand the physiological regulation and functions of Ataxin-2 homologs, the phylogenesis of sequences was analyzed. Human ATXN2 harbors multiple alternative start codons, e.g. from an intrinsically disordered se-quence (IDR) present since armadillo, or from the polyQ sequence that arose since amphibians, or from the LSm domain since primitive eukaryotes. Multiple smaller isoforms also exist across the C-terminus. Therapeutic knockdown of polyQ expansions in human ATXN2 should selectively target exon 1B. PolyQ repeats developed repeat-edly, usually framed and often interrupted by (poly)Pro, originally near PAM2. The LSmAD sequence appeared in algae as the characteristic Ataxin-2 feature with strong conservation. Frequently, Ataxin-2 has added domains, likely due to transcriptional readthrough of neighbor genes during cell stress. These chimerisms show enrichment of rRNA processing; nutrient store mobilization; membrane strengthening via lipid, protein, and glycosylated components; and cell protrusions. Thus, any mutation of Ataxin-2 has complex effects, also affecting membrane resilience.
2025-11-27 | Isotopic H/D Exchange in Hydrogen Bonds Between the Nitrogenous Bases of the CAG Repeat Tract Makes It Possible to Stabilize Its Expansion in the ATXN2 Gene.
Background: The isotopic composition of the body's internal environment can affect its functional state. Such effects are realized, among other things, by inserting deuterium atoms into hydrogen bonds between pairs of nitrogenous bases of DNA molecules and modifying their mechanical properties. Methods: This study uses a coarse-grained mathematical model of DNA. Results: It has been established that in a certain range of the magnitude of the torque, with the presence of a deuterium atom within it, stabilization of the CAG repeat tract is observed. In addition, it was found that, regardless of which base pair the deuterium atom falls into in the CAG repeat tract, its stability increases and the probability of hairpin formation decreases, which may interfere with the reading of genetic information from the site encoding glutamine. Conclusions: Single H/D substitutions in the CAG repeat tract of the ATXN2 gene increase its stability by reducing the formation of open states, regardless of the position of deuterium.
2025-10-28 | Targeting STAU1 prevents p53 apoptotic signaling in neurodegeneration.
Stress responses and neuronal death mediated by the p53 pathway play a central role in the progression of neurodegenerative disease, constituting a common target to extend neuronal function and survival. Interaction of p53 and its signaling network with RNA-binding proteins (RBPs) helps fine-tune its activation and the resulting cell fates. Preclinical therapeutics based on depletion of the RBP STAUFEN-1 (STAU1) protein successfully prevent neurodegeneration, however, the specific mechanisms are not fully understood. STAU1 is pathologically overabundant in multiple neurological disorders and contributes to neurodegeneration by exacerbating autophagy dysfunction, endoplasmic reticulum stress, and RNA-protein condensate accumulation. We previously showed that lowering STAU1 levels mitigates these disease-related features and prevents neuronal death in animal models of amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) and spinocerebellar ataxia type 2 (SCA2). Here, we show by combined transcriptomic and functional analyses that STAU1 reduction results in the inhibition of apoptosis through the p53 pathway. In both proliferating and post-mitotic cell types-human iPSC-derived neurons, mouse cortical neurons, SH-SY5Y cells, and fibroblasts-STAU1 reduction effectively prevented p53-mediated apoptosis and DNA damage induced by Nutlin-3 and etoposide. Further examination in C9orf72-expanded patient-derived fibroblasts and a C9orf72 mouse model of ALS/FTD, which exhibit baseline overabundance of STAU1 and activation of the p53 pathway, confirmed that STAU1 reduction also prevented p53-driven pro-apoptotic signaling. These findings establish STAU1 as a novel modulator of DNA damage and p53-dependent apoptosis, suggesting that targeting STAU1 could be a promising approach to prevent neurodegeneration in ALS/FTD.
2025-10-03 | A human Staufen1 BAC transgenic mouse exhibits abnormal autophagy and neurodegeneration across the central nervous system.
RNA-binding proteins (RBPs) play an essential role in development, normal functioning and human disease. Staufen1 (STAU1) is an RBP that regulates mRNA degradation and subcellular localization, and is part of the ATXN2 protein complex. Previously, we showed that STAU1 is overabundant in patient fibroblasts and in mouse models of Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and spinocerebellar ataxia type 2 (SCA2), where it is associated with impaired autophagic flux due to STAU1-mediated upregulation of mTOR translation. STAU1 overabundance and impaired autophagy cause accumulation of biomolecular condensates and abnormal unfolded protein response (UPR). We generated a mouse model expressing the entire human STAU1 gene (hSTAU1) in a bacterial artificial chromosome (BAC) construct. hSTAU1 in these mice was expressed in cerebral hemispheres, cerebellum and spinal cord, as well as cultured cortical neurons and cortical and spinal cord astrocytes and microglia. Expression of hSTAU1 caused dysregulated gene expression, abnormal autophagy, glial activation, and changes in neuronal marker proteins. All of these were significantly improved by reducing STAU1 abundance by RNAi, but exacerbated in BAC-STAU1 mice crossed with Prp-TDP-43(Q331K) transgenic mice. Similar results were also obtained in eye phenotypes in ALS- and SCA2-relevant fly models upon changing staufen-1 dosage. Despite the molecular changes, we observed no overt behavioral changes in mice up to 55 weeks of age, suggesting that STAU1 may function as an epistatic modifier of neuronal degeneration. The BAC-hSTAU1 mouse will be useful for developing therapies targeting the human STAU1 gene.
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2026-07-11 | Safety and preliminary efficacy of autologous bone marrow-derived mesenchymal stem cell transplantation in hereditary cerebellar ataxia: phase I/IIa clinical trial.
Hereditary cerebellar ataxias (HCA) encompass a spectrum of pathological conditions affecting the cerebellum. Currently, there is growing interest in the potential role of mesenchymal stem cells (MSCs) as an investigational therapeutic approach for this condition. Hence, the objective of this single-center, open-label, phase I/IIa clinical trial was to assess the safety and exploratory clinical and biomarker changes following a single intrathecal injection of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) in HCA. Ten confirmed patients with HCA entered the study and underwent a single dose of (1 × 106 cells/kg BW) intrathecal transplantation of BM-MSCs at passage 3. During the follow-up, patients were evaluated four times (one month before the intervention (-1), months 1, 3, and 6). Assessments included safety evaluation, Scale for the Assessment and Rating of Ataxia (SARA), GAD 65-antibody, and specific cytokines in the patient's serum and cerebrospinal fluid (CSF) samples. No severe adverse effects were observed following the cell transplantation procedure. A decreasing trend in SARA score was observed, with a statistically significant difference at month 6 compared with baseline. Except for one patient, GAD-65 antibody levels remained within the normal range in all patients. In one patient with markedly elevated baseline GAD-65 titers, serum and CSF GAD-65 levels decreased from 814 IU/mL and 781 IU/mL, respectively, to values within the normal range after 3 months. Significant changes were observed in selected inflammatory biomarkers, including decreased serum IL-6 at month 3, decreased CSF TNF-alpha at months 1 and 3, and increased serum IL-10 during follow-up. CSF IL-6 did not show a significant decrease. The findings support the short-term safety and tolerability of a single intrathecal dose of autologous BM-MSCs in this small HCA cohort. The study provides preliminary signals of possible clinical and biomarker changes; however, efficacy cannot be established due to the uncontrolled design, small sample size, disease heterogeneity, and short follow-up. Larger randomized controlled trials are required to validate these exploratory findings. This clinical trial was registered with the Iranian Registry of Clinical Trials (ID: IRCT20160809029275N3).
2026-04-13 | Cell-Based Therapies for Spinocerebellar Degenerations: A Systematic Review of Human Clinical Evidence.
Spinocerebellar degenerations (SCDs) are progressive hereditary and selected sporadic cerebellar neurodegenerative disorders with limited disease-modifying options. Cell-based therapies particularly, mesenchymal stromal/stem cells (MSCs), neural stem/progenitor cells, olfactory ensheathing cells (OECs), cord blood mononuclear cells (CBMCs), and hematopoietic stem cell transplantation (HSCT) are biologically plausible candidates, but their clinical efficacy and safety remain uncertain. We searched MEDLINE/PubMed, Embase, Scopus, Web of Science, and Cochrane Library from inception to 10 October 2025 (no language restrictions). The OSF-registered protocol prespecified eligibility, outcomes, and design-specific risk-of-bias (RoB) tools, with harmonized overall RoB judgments. We included human interventional or observational reports of cell-based or cell-derived products in hereditary ataxias and selected cerebellar-predominant degenerative syndromes within the OPCA/MSA-C spectrum, and extracted clinical efficacy, safety, and follow-up. Of 603 records screened, 17 reports met the protocol-defined inclusion criteria (15 full texts; 2 abstracts; 2006–2025). Most were small, uncontrolled case series, predominantly from China. Cell types: MSCs (9/17), HSCT in ataxia-telangiectasia (3/17), OECs (3/17), and others (neural stem cells [NSCs], CBMCs; 2/17). Routes were intrathecal and/or intravenous for MSC/CBMC; OEC/NSC were intracerebral/intraspinal; HSCT was delivered intravenously. Primary follow-up was typically 1–6 months. Safety was generally acceptable for MSC/CBMC/OEC with no treatment-related deaths and mostly transient post-procedural symptoms; HSCT exhibited regimen-related toxicities consistent with conditioning intensity. Efficacy signals were modest and often transient: short-term International Cooperative Ataxia Rating Scale (ICARS) improvements were reported across multiple series. Cell-based therapies for SCDs show biological plausibility and generally reassuring short-term safety, but current human evidence, dominated by uncontrolled, high-bias studies does not establish efficacy or durability. Priority should shift to rigorously controlled trials, standardized good manufacturing practice (GMP)-characterized products, blinded centralized ratings, careful control of co-interventions, and objective biomarkers.
2026-04-02 | IL-17A rescues motor deficits in a mouse model of Spinocerebellar Ataxia Type 2
Abstract Motor performance and coordination deficits are hallmarks of spinocerebellar ataxias, yet effective disease-modifying therapies remain limited. Here, we investigate the expression of the interleukin 17 receptor subunit A (IL-17RA) in cerebellum and assess the therapeutic potential of its ligand in a mouse model for Spinocerebellar Ataxia Type 2 (SCA2). We found that IL-17RA is highly enriched in cerebellar molecular layer interneurons (MLIs), which provide inhibitory input to Purkinje neurons. In-vitro electrophysiological recordings revealed that symptomatic SCA2 mice exhibited increased spontaneous inhibitory synaptic input onto Purkinje neurons, which was normalized by IL-17A application to control levels. Concomitantly, IL-17A application restored Purkinje neuron firing, a parameter characteristically reduced in SCA2 mice. Behaviorally, intranasal administration of IL-17A restored motor performance of symptomatic SCA2 mice to control levels in both rotarod and beam-crossing assays. Collectively, our results indicate that IL-17A rescues Purkinje neuron dysfunction and motor deficits in SCA2 mice, highlighting IL-17A signaling as a promising therapeutic target for spinocerebellar ataxia.
2025-01-03 | Transcriptomic analysis of repeat expansion-ataxias uncovers distinct non-neuronal cell type-specific signatures of disease across the human brain
Abstract Hereditary ataxias are a heterogeneous group of neurogenetic conditions characterised by the clinical syndrome of progressive loss of coordination from neurodegeneration of the cerebellum. A commonality across the most prevalent ataxias is the underlying disease mechanism secondary to expansions of short tandem DNA repeats. There is currently an incomplete understanding of the pathogenic mechanisms of these repeat expansion disorders, a core feature of which revolves around RNA-dysregulation. In this study, we used both bulk and single nuclear RNA-sequencing to study post-mortem brain tissue of human donors with a range of repeat-expansion ataxias to reveal further mechanistic insights. We compared post-mortem paired cerebellar and frontal cortex tissue bulk RNA-sequencing data from 23 ataxia patients and 22 sex-, age-matched controls from two brain banks (spinocerebellar ataxia (SCA)1, SCA2, SCA6, SCA7, SCA17, Friedreich’s ataxia (FRDA), and 7 cases with unknown molecular diagnoses). We analysed bulk RNA-sequencing data for transcript usage, differential and cell-type-specific expression to transcriptomically profile these diseases. We also generated single nuclear RNA-sequencing data of the cerebellum from donors with SCA1, SCA2, SCA6 and FRDA to decipher changes in cell type proportions in the disease state. Using this approach, we found that: (i) despite the commonalities in the genetics of ataxia, there were components of their transcriptional signatures which were distinct; (ii) there were extensive transcriptional changes evident not only in the cerebellum but also the frontal cortex in ataxia cases; (iii) activation of immune and inflammatory pathways, as well as involvement of non-neuronal cell types was a feature of all ataxias to a lesser or greater extent. This study provides a novel resource to understand the mechanisms of disease in ataxia. Furthermore, taken together, these results highlight immune pathways and the role of non-neuronal cell types as early and potentially important therapeutic targets. These findings provide a map of transcriptomic changes in ataxia to further understanding of the underlying pathogenesis.
2024-11-13 | Post-symptomatic administration of hMSCs exerts therapeutic effects in SCA2 mice.
Defects in the ataxin-2 (ATXN-2) protein and CAG trinucleotide repeat expansion in its coding gene, Atxn-2, cause the neurodegenerative disorder spinocerebellar ataxia type 2 (SCA2). While clinical studies suggest potential benefits of human-derived mesenchymal stem cells (hMSCs) for treating various ataxias, the exact mechanisms underlying their therapeutic effects and interaction with host tissue to stimulate neurotrophin expression remain unclear specifically in the context of SCA2. Human bone marrow-derived MSCs (hMSCs) were injected into the cisterna magna of 26-week-old wild-type and SCA2 mice. Mice were assessed for impaired motor coordination using the accelerating rotarod, open field test, and composite phenotype scoring. At 50 weeks, the cerebellum vermis was harvested for protein assessment and immunohistochemical analysis. Significant loss of NeuN and calbindin was observed in 25-week-old SCA2 mice. However, after receiving multiple injections of hMSCs starting at 26 weeks of age, these mice exhibited a significant improvement in abnormal motor performance and a protective effect on Purkinje cells. This beneficial effect persisted until the mice reached 50 weeks of age, at which point they were sacrificed to study further mechanistic events triggered by the administration of hMSCs. Calbindin-positive cells in the Purkinje cell layer expressed bone-derived neurotrophic factor after hMSC administration, contributing to the protection of cerebellar neurons from cell death. In conclusion, repeated administration of hMSCs shows promise in alleviating SCA2 symptoms by preserving Purkinje cells, improving neurotrophic support, and reducing inflammation, ultimately leading to the preservation of locomotor function in SCA2 mice.
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