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Molecular Brain Mar 2024Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3, is a fatal neurodegenerative disease that causes loss of balance and motor co-ordination,...
Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3, is a fatal neurodegenerative disease that causes loss of balance and motor co-ordination, eventually leading to paralysis. It is caused by the autosomal dominant inheritance of a long CAG trinucleotide repeat sequence within the ATXN3 gene, encoding for an expanded polyglutamine (polyQ) repeat sequence within the ataxin-3 protein. Ataxin-3 containing an expanded polyQ repeat is known to be highly prone to intraneuronal aggregation, and previous studies have demonstrated that protein quality control pathways, such as autophagy, are impaired in MJD patients and animal models of the disease. In this study, we tested the therapeutic potential of spermidine on zebrafish and rodent models of MJD to determine its capacity to induce autophagy and improve functional output. Spermidine treatment of transgenic MJD zebrafish induced autophagy and resulted in increased distances swum by the MJD zebrafish. Interestingly, treatment of the CMVMJD135 mouse model of MJD with spermidine added to drinking water did not produce any improvement in motor behaviour assays, neurological testing or neuropathology. In fact, wild type mice treated with spermidine were found to have decreased rotarod performance when compared to control animals. Immunoblot analysis of protein lysates extracted from mouse cerebellar tissue found little differences between the groups, except for an increased level of phospho-ULK1 in spermidine treated animals, suggesting that autophagy was indeed induced. As we detected decreased motor performance in wild type mice following treatment with spermidine, we conducted follow up studies into the effects of spermidine treatment in zebrafish. Interestingly, we found that in addition to inducing autophagy, spermidine treatment also induced apoptosis, particularly in wild type zebrafish. These findings suggest that spermidine treatment may not be therapeutically beneficial for the treatment of MJD, and in fact warrants caution due to the potential negative side effects caused by induction of apoptosis.
Topics: Humans; Animals; Mice; Neurodegenerative Diseases; Spermidine; Zebrafish; Apoptosis; Autophagy; Disease Models, Animal; Machado-Joseph Disease
PubMed: 38443995
DOI: 10.1186/s13041-024-01085-7 -
Cell Reports Mar 2024The ataxia telangiectasia mutated (ATM) protein kinase is a master regulator of the DNA damage response and also an important sensor of oxidative stress. Analysis of...
The ataxia telangiectasia mutated (ATM) protein kinase is a master regulator of the DNA damage response and also an important sensor of oxidative stress. Analysis of gene expression in ataxia-telangiectasia (A-T) patient brain tissue shows that large-scale transcriptional changes occur in patient cerebellum that correlate with the expression level and guanine-cytosine (GC) content of transcribed genes. In human neuron-like cells in culture, we map locations of poly(ADP-ribose) and RNA-DNA hybrid accumulation genome-wide with ATM inhibition and find that these marks also coincide with high transcription levels, active transcription histone marks, and high GC content. Antioxidant treatment reverses the accumulation of R-loops in transcribed regions, consistent with the central role of reactive oxygen species in promoting these lesions. Based on these results, we postulate that transcription-associated lesions accumulate in ATM-deficient cells and that the single-strand breaks and PARylation at these sites ultimately generate changes in transcription that compromise cerebellum function and lead to neurodegeneration over time in A-T patients.
Topics: Humans; Poly Adenosine Diphosphate Ribose; RNA; Ataxia Telangiectasia Mutated Proteins; DNA; Ataxia Telangiectasia; DNA Repair; DNA Damage; Cell Cycle Proteins
PubMed: 38442018
DOI: 10.1016/j.celrep.2024.113896 -
Stem Cell Research Apr 2024Spastic Ataxias (SA) are a group of neurodegenerative disorders with combined pyramidal and cerebellar system affection, leading to an overlap phenotype between...
Spastic Ataxias (SA) are a group of neurodegenerative disorders with combined pyramidal and cerebellar system affection, leading to an overlap phenotype between Hereditary Spastic Paraplegias (HSP) and Cerebellar Ataxias (CA). Here we describe the generation of iPSCs from three unrelated patients with an ultra-rare subtype of SA caused by compound heterozygous mutations in POLR3A, that encodes the largest subunit of RNA polymerase III. iPSCs were reprogrammed from normal human dermal fibroblasts (NHDFs) using episomal reprogramming with integration-free plasmid vectors: HIHRSi004-A, derived from a 44 year-old male carrying the mutations c.1909 + 22G > A/c.3944_3945delTG, HIHRSi005-A obtained from a 66 year-old male carrying the mutations c.1909 + 22G > A/c.1531C > T, and HIHRSi006-A from a 27 year-old male carrying the mutations c.1909 + 22G > A/c.2472_2472delC (ENST00000372371.8).
Topics: Adult; Aged; Humans; Male; Cell Line; Induced Pluripotent Stem Cells; Intellectual Disability; Muscle Spasticity; Mutation; Optic Atrophy; RNA Polymerase III; Spinocerebellar Ataxias
PubMed: 38437768
DOI: 10.1016/j.scr.2024.103363 -
Neurobiology of Disease Apr 2024Spinocerebellar ataxia type 3 (SCA3)/Machado-Joseph disease (MJD) is a heritable proteinopathy disorder, whose causative gene, ATXN3, undergoes alternative splicing....
Spinocerebellar ataxia type 3 (SCA3)/Machado-Joseph disease (MJD) is a heritable proteinopathy disorder, whose causative gene, ATXN3, undergoes alternative splicing. Ataxin-3 protein isoforms differ in their toxicity, suggesting that certain ATXN3 splice variants may be crucial in driving the selective toxicity in SCA3. Using RNA-seq datasets we identified and determined the abundance of annotated ATXN3 transcripts in blood (n = 60) and cerebellum (n = 12) of SCA3 subjects and controls. The reference transcript (ATXN3-251), translating into an ataxin-3 isoform harbouring three ubiquitin-interacting motifs (UIMs), showed the highest abundance in blood, while the most abundant transcript in the cerebellum (ATXN3-208) was of unclear function. Noteworthy, two of the four transcripts that encode full-length ataxin-3 isoforms but differ in the C-terminus were strongly related with tissue expression specificity: ATXN3-251 (3UIM) was expressed in blood 50-fold more than in the cerebellum, whereas ATXN3-214 (2UIM) was expressed in the cerebellum 20-fold more than in the blood. These findings shed light on ATXN3 alternative splicing, aiding in the comprehension of SCA3 pathogenesis and providing guidance in the design of future ATXN3 mRNA-lowering therapies.
Topics: Humans; Machado-Joseph Disease; Ataxin-3; Nerve Tissue Proteins; Cerebellum; Protein Isoforms; Repressor Proteins
PubMed: 38423193
DOI: 10.1016/j.nbd.2024.106456 -
STAR Protocols Mar 2024Purkinje neuron degeneration characterizes spinocerebellar ataxia type 1, yet the comprehension of the impact on the broader cerebellar circuit remains incomplete. We...
Purkinje neuron degeneration characterizes spinocerebellar ataxia type 1, yet the comprehension of the impact on the broader cerebellar circuit remains incomplete. We here detail simultaneous in vivo two-photon calcium imaging of diverse neuronal populations in the cerebellar cortex of Sca1 mice while they are navigating a virtual environment. We outline surgical procedures and protocols to chronically record from identical neurons, and we detail data post-processing and analysis to delineate disease-related alterations in neuronal activity and sensorimotor-driven response properties. For complete details on the use and execution of this protocol, please refer to Pilotto et al..
Topics: Mice; Animals; Calcium; Rodentia; Mice, Transgenic; Spinocerebellar Ataxias; Cerebellum
PubMed: 38412102
DOI: 10.1016/j.xpro.2024.102911 -
MicroPublication Biology 2024Inhibition of acetylcholinesterase (AChE) is a common used treatment option for Alzheimer's disease. However, there has been limited research on the potential use of...
Inhibition of acetylcholinesterase (AChE) is a common used treatment option for Alzheimer's disease. However, there has been limited research on the potential use of AChE inhibitors for the treatment of Machado-Joseph disease (MJD)/Spinocerebellar Ataxia 3 (SCA3), in spite of the positive results using AChE inhibitors in patients with other inherited ataxias. MJD/SCA3, the most common form of dominant Spinocerebellar Ataxia worldwide, is caused by an expansion of the polyglutamine tract within the ataxin-3 protein, and is characterized by motor impairments. Our study shows that administration of the AChE inhibitor neostigmine is beneficial in treating the locomotion defective phenotype of a SCA3/MJD model of and highlights the potential contribution of AChE enzymes to mutant ataxin-3-mediated toxicity.
PubMed: 38404918
DOI: 10.17912/micropub.biology.001086 -
Human Genetics Mar 2024Spinocerebellar ataxia subtype 37 (SCA37) is a rare disease originally identified in ataxia patients from the Iberian Peninsula with a pure cerebellar syndrome. SCA37...
Novel genotype-phenotype correlations, differential cerebellar allele-specific methylation, and a common origin of the (ATTTC) insertion in spinocerebellar ataxia type 37.
Spinocerebellar ataxia subtype 37 (SCA37) is a rare disease originally identified in ataxia patients from the Iberian Peninsula with a pure cerebellar syndrome. SCA37 patients carry a pathogenic intronic (ATTTC)n repeat insertion flanked by two polymorphic (ATTTT)n repeats in the Disabled-1 (DAB1) gene leading to cerebellar dysregulation. Herein, we determine the precise configuration of the pathogenic 5'(ATTTT)n-(ATTTC)n-3'(ATTTT)n SCA37 alleles by CRISPR-Cas9 and long-read nanopore sequencing, reveal their epigenomic signatures in SCA37 lymphocytes, fibroblasts, and cerebellar samples, and establish new molecular and clinical correlations. The 5'(ATTTT)n-(ATTTC)n-3'(ATTTT)n pathogenic allele configurations revealed repeat instability and differential methylation signatures. Disease age of onset negatively correlated with the (ATTTC)n, and positively correlated with the 3'(ATTTT)n. Geographic origin and gender significantly correlated with age of onset. Furthermore, significant predictive regression models were obtained by machine learning for age of onset and disease evolution by considering gender, the (ATTTC)n, the 3'(ATTTT)n, and seven CpG positions differentially methylated in SCA37 cerebellum. A common 964-kb genomic region spanning the (ATTTC)n insertion was identified in all SCA37 patients analysed from Portugal and Spain, evidencing a common origin of the SCA37 mutation in the Iberian Peninsula originating 859 years ago (95% CI 647-1378). In conclusion, we demonstrate an accurate determination of the size and configuration of the regulatory 5'(ATTTT)n-(ATTTC)n-3'(ATTTT)n repeat tract, avoiding PCR bias amplification using CRISPR/Cas9-enrichment and nanopore long-read sequencing, resulting relevant for accurate genetic diagnosis of SCA37. Moreover, we determine novel significant genotype-phenotype correlations in SCA37 and identify differential cerebellar allele-specific methylation signatures that may underlie DAB1 pathogenic dysregulation.
Topics: Humans; Spinocerebellar Ataxias; DNA Methylation; Female; Male; Alleles; Cerebellum; Genetic Association Studies; Middle Aged; Adult; Mutagenesis, Insertional; Aged; Age of Onset
PubMed: 38396267
DOI: 10.1007/s00439-024-02644-7 -
Cells Feb 2024Cerebellar ataxias are a wide heterogeneous group of movement disorders. Within this broad umbrella of diseases, there are both genetics and sporadic forms. The clinical... (Review)
Review
Cerebellar ataxias are a wide heterogeneous group of movement disorders. Within this broad umbrella of diseases, there are both genetics and sporadic forms. The clinical presentation of these conditions can exhibit a diverse range of symptoms across different age groups, spanning from pure cerebellar manifestations to sensory ataxia and multisystemic diseases. Over the last few decades, advancements in our understanding of genetics and molecular pathophysiology related to both dominant and recessive ataxias have propelled the field forward, paving the way for innovative therapeutic strategies aimed at preventing and arresting the progression of these diseases. Nevertheless, the rarity of certain forms of ataxia continues to pose challenges, leading to limited insights into the etiology of the disease and the identification of target pathways. Additionally, the lack of suitable models hampers efforts to comprehensively understand the molecular foundations of disease's pathophysiology and test novel therapeutic interventions. In the following review, we describe the epidemiology, symptomatology, and pathological progression of hereditary ataxia, including both the prevalent and less common forms of these diseases. Furthermore, we illustrate the diverse molecular pathways and therapeutic approaches currently undergoing investigation in both pre-clinical studies and clinical trials. Finally, we address the existing and anticipated challenges within this field, encompassing both basic research and clinical endeavors.
Topics: Humans; Spinocerebellar Degenerations; Cerebellar Ataxia; Ataxia; Cerebellum
PubMed: 38391932
DOI: 10.3390/cells13040319 -
Journal of Neurology, Neurosurgery, and... Jun 2024Spinal cord damage is a feature of many spinocerebellar ataxias (SCAs), but well-powered in vivo studies are lacking and links with disease severity and progression...
BACKGROUND
Spinal cord damage is a feature of many spinocerebellar ataxias (SCAs), but well-powered in vivo studies are lacking and links with disease severity and progression remain unclear. Here we characterise cervical spinal cord morphometric abnormalities in SCA1, SCA2, SCA3 and SCA6 using a large multisite MRI dataset.
METHODS
Upper spinal cord (vertebrae C1-C4) cross-sectional area (CSA) and eccentricity (flattening) were assessed using MRI data from nine sites within the ENIGMA-Ataxia consortium, including 364 people with ataxic SCA, 56 individuals with preataxic SCA and 394 nonataxic controls. Correlations and subgroup analyses within the SCA cohorts were undertaken based on disease duration and ataxia severity.
RESULTS
Individuals in the ataxic stage of SCA1, SCA2 and SCA3, relative to non-ataxic controls, had significantly reduced CSA and increased eccentricity at all examined levels. CSA showed large effect sizes (>2.0) and correlated with ataxia severity (r<-0.43) and disease duration (r<-0.21). Eccentricity correlated only with ataxia severity in SCA2 (r=0.28). No significant spinal cord differences were evident in SCA6. In preataxic individuals, CSA was significantly reduced in SCA2 (=1.6) and SCA3 (=1.7), and the SCA2 group also showed increased eccentricity (=1.1) relative to nonataxic controls. Subgroup analyses confirmed that CSA and eccentricity are abnormal in early disease stages in SCA1, SCA2 and SCA3. CSA declined with disease progression in all, whereas eccentricity progressed only in SCA2.
CONCLUSIONS
Spinal cord abnormalities are an early and progressive feature of SCA1, SCA2 and SCA3, but not SCA6, which can be captured using quantitative MRI.
Topics: Humans; Spinocerebellar Ataxias; Male; Female; Middle Aged; Adult; Magnetic Resonance Imaging; Genotype; Aged; Spinal Cord; Cervical Cord; Severity of Illness Index; Case-Control Studies
PubMed: 38383154
DOI: 10.1136/jnnp-2023-332696 -
JCI Insight Feb 2024Radiotherapy induces a type I interferon-mediated (T1IFN-mediated) antitumoral immune response that we hypothesized could be potentiated by a first-in-class ataxia...
Radiotherapy induces a type I interferon-mediated (T1IFN-mediated) antitumoral immune response that we hypothesized could be potentiated by a first-in-class ataxia telangiectasia mutated (ATM) inhibitor, leading to enhanced innate immune signaling, T1IFN expression, and sensitization to immunotherapy in pancreatic cancer. We evaluated the effects of AZD1390 or a structurally related compound, AZD0156, on innate immune signaling and found that both inhibitors enhanced radiation-induced T1IFN expression via the POLIII/RIG-I/MAVS pathway. In immunocompetent syngeneic mouse models of pancreatic cancer, ATM inhibitor enhanced radiation-induced antitumoral immune responses and sensitized tumors to anti-PD-L1, producing immunogenic memory and durable tumor control. Therapeutic responses were associated with increased intratumoral CD8+ T cell frequency and effector function. Tumor control was dependent on CD8+ T cells, as therapeutic efficacy was blunted in CD8+ T cell-depleted mice. Adaptive immune responses to combination therapy provided systemic control of contralateral tumors outside of the radiation field. Taken together, we show that a clinical candidate ATM inhibitor enhances radiation-induced T1IFN, leading to both innate and subsequent adaptive antitumoral immune responses and sensitization of otherwise resistant pancreatic cancer to immunotherapy.
Topics: Animals; Mice; Interferon Type I; Ataxia Telangiectasia; Pancreatic Neoplasms; Immunity; Pyridines; Quinolones
PubMed: 38376927
DOI: 10.1172/jci.insight.168824