scholarly journals GAA repeat expansion mutation mouse models of Friedreich ataxia exhibit oxidative stress leading to progressive neuronal and cardiac pathology

Genomics ◽  
2006 ◽  
Vol 88 (5) ◽  
pp. 580-590 ◽  
Author(s):  
Sahar Al-Mahdawi ◽  
Ricardo Mouro Pinto ◽  
Dhaval Varshney ◽  
Lorraine Lawrence ◽  
Margaret B. Lowrie ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mouse Models ◽  
Friedreich Ataxia ◽  
Repeat Expansion ◽  
Cardiac Pathology ◽  
Repeat Expansion Mutation ◽  
Gaa Repeat Expansion ◽  
Expansion Mutation

scholarly journals Emerging Mechanisms Underpinning Neurophysiological Impairments in C9ORF72 Repeat Expansion-Mediated Amyotrophic Lateral Sclerosis/Frontotemporal Dementia

2021 ◽  
Vol 15 ◽  
Author(s):  
Iris-Stefania Pasniceanu ◽  
Manpreet Singh Atwal ◽  
Cleide Dos Santos Souza ◽  
Laura Ferraiuolo ◽  
Matthew R. Livesey
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Frontotemporal Dementia ◽  
Motor Neurons ◽  
Molecular Mechanisms ◽  
Repeat Expansion ◽  
Neuronal Function ◽  
Repeat Expansion Mutation ◽  
Expansion Mutation ◽  
The Impact ◽  
Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are characterized by degeneration of upper and lower motor neurons and neurons of the prefrontal cortex. The emergence of the C9ORF72 hexanucleotide repeat expansion mutation as the leading genetic cause of ALS and FTD has led to a progressive understanding of the multiple cellular pathways leading to neuronal degeneration. Disturbances in neuronal function represent a major subset of these mechanisms and because such functional perturbations precede degeneration, it is likely that impaired neuronal function in ALS/FTD plays an active role in pathogenesis. This is supported by the fact that ALS/FTD patients consistently present with neurophysiological impairments prior to any apparent degeneration. In this review we summarize how the discovery of the C9ORF72 repeat expansion mutation has contributed to the current understanding of neuronal dysfunction in ALS/FTD. Here, we discuss the impact of the repeat expansion on neuronal function in relation to intrinsic excitability, synaptic, network and ion channel properties, highlighting evidence of conserved and divergent pathophysiological impacts between cortical and motor neurons and the influence of non-neuronal cells. We further highlight the emerging association between these dysfunctional properties with molecular mechanisms of the C9ORF72 mutation that appear to include roles for both, haploinsufficiency of the C9ORF72 protein and aberrantly generated dipeptide repeat protein species. Finally, we suggest that relating key pathological observations in C9ORF72 repeat expansion ALS/FTD patients to the mechanistic impact of the C9ORF72 repeat expansion on neuronal function will lead to an improved understanding of how neurophysiological dysfunction impacts upon pathogenesis.

scholarly journals Modifiers of Somatic Repeat Instability in Mouse Models of Friedreich Ataxia and the Fragile X-Related Disorders: Implications for the Mechanism of Somatic Expansion in Huntington’s Disease

2021 ◽  
Vol 10 (1) ◽  
pp. 149-163
Author(s):  
Xiaonan Zhao ◽  
Daman Kumari ◽  
Carson J. Miller ◽  
Geum-Yi Kim ◽  
Bruce Hayward ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Mouse Models ◽  
Fragile X ◽  
Friedreich Ataxia ◽  
Disease Onset ◽  
Neuronal Cell ◽  
Repeat Expansion ◽  
Cag Repeat ◽  
Dna Repeats

Huntington’s disease (HD) is one of a large group of human disorders that are caused by expanded DNA repeats. These repeat expansion disorders can have repeat units of different size and sequence that can be located in any part of the gene and, while the pathological consequences of the expansion can differ widely, there is evidence to suggest that the underlying mutational mechanism may be similar. In the case of HD, the expanded repeat unit is a CAG trinucleotide located in exon 1 of the huntingtin (HTT) gene, resulting in an expanded polyglutamine tract in the huntingtin protein. Expansion results in neuronal cell death, particularly in the striatum. Emerging evidence suggests that somatic CAG expansion, specifically expansion occurring in the brain during the lifetime of an individual, contributes to an earlier disease onset and increased severity. In this review we will discuss mouse models of two non-CAG repeat expansion diseases, specifically the Fragile X-related disorders (FXDs) and Friedreich ataxia (FRDA). We will compare and contrast these models with mouse and patient-derived cell models of various other repeat expansion disorders and the relevance of these findings for somatic expansion in HD. We will also describe additional genetic factors and pathways that modify somatic expansion in the FXD mouse model for which no comparable data yet exists in HD mice or humans. These additional factors expand the potential druggable space for diseases like HD where somatic expansion is a significant contributor to disease impact.

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