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Phenotype and management of neurologic intronic repeat disorders (NIRDs). Rev Neurol (Paris) 2023; 179:173-182. [PMID: 36371266 DOI: 10.1016/j.neurol.2022.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 09/15/2022] [Accepted: 09/20/2022] [Indexed: 11/11/2022]
Abstract
During recent years an increasing number of neurologic disorders due to expanded tri-, tetra-, penta-, or hexa-nucleotide repeat motifs in introns of various genes have been described (neurologic intronic repeat disorders (NIRDs)). The repeat may be pathogenic in the heterozygous or homozygous form. Repeat lengths vary considerably and can be stable or unstable during transmission to the next generation. The most well-known NIRDs are Friedreich ataxia, spinocerebellar ataxia types-10, -31, and -36, CANVAS, C9Orf72 familial amyotrophic lateral sclerosis (fALS), and myotonic dystrophy-2 (MD2). Phenotypically, NIRDs manifest as mono-organ (e.g. spinocerebellar ataxia type 31) or multi-organ disease (e.g. Friedreich ataxia, myotonic dystrophy-2). A number of other more rare NIRDs have been recently detected. This review aims at summarising and discussing previous findings and recent advances concerning the etiology, pathophysiology, clinical presentation, and therapeutic management of the most common NIRDs.
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Kurosaki T, Ashizawa T. The genetic and molecular features of the intronic pentanucleotide repeat expansion in spinocerebellar ataxia type 10. Front Genet 2022; 13:936869. [PMID: 36199580 PMCID: PMC9528567 DOI: 10.3389/fgene.2022.936869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 08/25/2022] [Indexed: 11/13/2022] Open
Abstract
Spinocerebellar ataxia type 10 (SCA10) is characterized by progressive cerebellar neurodegeneration and, in many patients, epilepsy. This disease mainly occurs in individuals with Indigenous American or East Asian ancestry, with strong evidence supporting a founder effect. The mutation causing SCA10 is a large expansion in an ATTCT pentanucleotide repeat in intron 9 of the ATXN10 gene. The ATTCT repeat is highly unstable, expanding to 280–4,500 repeats in affected patients compared with the 9–32 repeats in normal individuals, one of the largest repeat expansions causing neurological disorders identified to date. However, the underlying molecular basis of how this huge repeat expansion evolves and contributes to the SCA10 phenotype remains largely unknown. Recent progress in next-generation DNA sequencing technologies has established that the SCA10 repeat sequence has a highly heterogeneous structure. Here we summarize what is known about the structure and origin of SCA10 repeats, discuss the potential contribution of variant repeats to the SCA10 disease phenotype, and explore how this information can be exploited for therapeutic benefit.
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Affiliation(s)
- Tatsuaki Kurosaki
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, United States
- Center for RNA Biology, University of Rochester, Rochester, NY, United States
- *Correspondence: Tatsuaki Kurosaki, ; Tetsuo Ashizawa,
| | - Tetsuo Ashizawa
- Stanley H. Appel Department of Neurology, Houston Methodist Research Institute and Weil Cornell Medical College at Houston Methodist Houston, TX, United States
- *Correspondence: Tatsuaki Kurosaki, ; Tetsuo Ashizawa,
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Mechanistic and Therapeutic Insights into Ataxic Disorders with Pentanucleotide Expansions. Cells 2022; 11:cells11091567. [PMID: 35563872 PMCID: PMC9099484 DOI: 10.3390/cells11091567] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/02/2022] [Accepted: 05/05/2022] [Indexed: 02/01/2023] Open
Abstract
Pentanucleotide expansion diseases constitute a special class of neurodegeneration. The repeat expansions occur in non-coding regions, have likely arisen from Alu elements, and often result in autosomal dominant or recessive phenotypes with underlying cerebellar neuropathology. When transcribed (potentially bidirectionally), the expanded RNA forms complex secondary and tertiary structures that can give rise to RNA-mediated toxicity, including protein sequestration, pentapeptide synthesis, and mRNA dysregulation. Since several of these diseases have recently been discovered, our understanding of their pathological mechanisms is limited, and their therapeutic interventions underexplored. This review aims to highlight new in vitro and in vivo insights into these incurable diseases.
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Lalonde R, Strazielle C. Motor Performances of Spontaneous and Genetically Modified Mutants with Cerebellar Atrophy. THE CEREBELLUM 2019; 18:615-634. [PMID: 30820866 DOI: 10.1007/s12311-019-01017-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Chance discovery of spontaneous mutants with atrophy of the cerebellar cortex has unearthed genes involved in optimizing motor coordination. Rotorod, stationary beam, and suspended wire tests are useful in delineating behavioral phenotypes of spontaneous mutants with cerebellar atrophy such as Grid2Lc, Grid2ho, Rorasg, Agtpbp1pcd, Relnrl, and Dab1scm. Likewise, transgenic or null mutants serving as experimental models of spinocerebellar ataxia (SCA) are phenotyped with the same tests. Among experimental models of autosomal dominant SCA, rotorod deficits were reported in SCA1 to 3, SCA5 to 8, SCA14, SCA17, and SCA27 and stationary beam deficits in SCA1 to 3, SCA5, SCA6, SCA13, SCA17, and SCA27. Beam tests are sensitive to experimental therapies of various kinds including molecules affecting glutamate signaling, mesenchymal stem cells, anti-oligomer antibodies, lentiviral vectors carrying genes, interfering RNAs, or neurotrophic factors, and interbreeding with other mutants.
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Affiliation(s)
- Robert Lalonde
- Department of Psychology, University of Rouen, 76821, Mont-Saint-Aignan Cedex, France.
| | - Catherine Strazielle
- Laboratory of Stress, Immunity, and Pathogens EA7300, and CHRU of Nancy, University of Lorraine, 54500, Vandoeuvre-les-Nancy, France
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Ashizawa AT, Holt J, Faust K, Liu W, Tiwari A, Zhang N, Ashizawa T. Intravenously Administered Novel Liposomes, DCL64, Deliver Oligonucleotides to Cerebellar Purkinje Cells. THE CEREBELLUM 2019; 18:99-108. [PMID: 29987489 DOI: 10.1007/s12311-018-0961-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cerebellar Purkinje cells (PCs) show conspicuous damages in many ataxic disorders. Targeted delivery of short nucleic acids, such as antisense oligonucleotides, to PCs may be a potential treatment for ataxic disorders, especially spinocerebellar ataxias (SCAs), which are mostly caused by a gain of toxic function of the mutant RNA or protein. However, oligonucleotides do not cross the blood-brain barrier (BBB), necessitating direct delivery into the central nervous system (CNS) through intra-thecal, intra-cisternal, intra-cerebral ventricular, or stereotactic parenchymal administration. We have developed a novel liposome (100 to 200 nm in diameter) formulation, DCL64, composed of dipalmitoyl-phosphatidylcholine, cholesterol, and poloxamer L64, which incorporates oligonucleotides efficiently (≥ 70%). Confocal microscopy showed that DCL64 was selectively taken up by brain microvascular endothelial cells by interacting with low-density lipoprotein receptor (LDLr) family members on cell surface, but not with other types of lipid receptors such as caveolin or scavenger receptor class B type 1. LDLr family members are implicated in brain microvascular endothelial cell endocytosis/transcytosis, and are abundantly localized on cerebellar PCs. Intravenous administration of DCL64 in normal mice showed distribution of oligonucleotides to the brain, preferentially in PCs. Mice that received DCL64 showed no adverse effect on hematological, hepatic, and renal functions in blood tests, and no histopathological abnormalities in major organs. These studies suggest that DCL64 delivers oligonucleotides to PCs across the BBB via intravenous injection with no detectable adverse effects. This property potentially makes DCL64 particularly attractive as a delivery vehicle in treatments of SCAs.
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Affiliation(s)
- Ana Tari Ashizawa
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA.,Department of Neuroscience, University of Florida, Gainesville, FL, USA.,Bio-Path Holdings, Inc., Bellaire, TX, USA
| | - Jenny Holt
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA.,Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Kelsey Faust
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA.,Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Weier Liu
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA.,Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | - Anjana Tiwari
- Stanley H. Appel Department of Neurology, Houston Methodist Research Institute, 6670 Bertner Avenue, R11-117, Houston, TX, 77030, USA
| | - Nan Zhang
- Stanley H. Appel Department of Neurology, Houston Methodist Research Institute, 6670 Bertner Avenue, R11-117, Houston, TX, 77030, USA
| | - Tetsuo Ashizawa
- McKnight Brain Institute, University of Florida, Gainesville, FL, USA. .,Department of Neurology, University of Florida, Gainesville, FL, USA. .,Stanley H. Appel Department of Neurology, Houston Methodist Research Institute, 6670 Bertner Avenue, R11-117, Houston, TX, 77030, USA.
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