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Hanrahan J, Locke DP, Cahill LS. Magnetic Resonance Imaging to Detect Structural Brain Changes in Huntington's Disease: A Review of Data from Mouse Models. J Huntingtons Dis 2024; 13:279-299. [PMID: 39213087 DOI: 10.3233/jhd-240045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Structural magnetic resonance imaging (MRI) is a powerful tool to visualize 3D neuroanatomy and assess pathology and disease progression in neurodegenerative disorders such as Huntington's disease (HD). The development of mouse models of HD that reproduce many of the psychiatric, motor and cognitive impairments observed in human HD has improved our understanding of the disease and provided opportunities for testing novel therapies. Similar to the clinical scenario, MRI of mouse models of HD demonstrates onset and progression of brain pathology. Here, we provided an overview of the articles that used structural MRI in mouse models of HD to date, highlighting the differences between studies and models and describing gaps in the current state of knowledge and recommendations for future studies.
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Affiliation(s)
- Jenna Hanrahan
- Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Drew P Locke
- Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Lindsay S Cahill
- Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
- Discipline of Radiology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
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Handley RR, Reid SJ, Burch Z, Jacobsen JC, Gillis T, Correia K, Rudiger SR, McLaughlin CJ, Bawden CS, MacDonald ME, Wheeler VC, Snell RG. Somatic CAG Repeat Stability in a Transgenic Sheep Model of Huntington's Disease. J Huntingtons Dis 2024; 13:33-40. [PMID: 38393920 DOI: 10.3233/jhd-231516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
Somatic instability of the huntingtin (HTT) CAG repeat mutation modifies age-at-onset of Huntington's disease (HD). Understanding the mechanism and pathogenic consequences of instability may reveal therapeutic targets. Using small-pool PCR we analyzed CAG instability in the OVT73 sheep model which expresses a full-length human cDNA HTT transgene. Analyses of five- and ten-year old sheep revealed the transgene (CAG)69 repeat was remarkably stable in liver, striatum, and other brain tissues. As OVT73 sheep at ten years old have minimal cell death and behavioral changes, our findings support instability of the HTT expanded-CAG repeat as being required for the progression of HD.
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Affiliation(s)
- Renee R Handley
- Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Suzanne J Reid
- Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Zoe Burch
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Jessie C Jacobsen
- Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Tammy Gillis
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Kevin Correia
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Skye R Rudiger
- Molecular Biology and Reproductive Technology, Laboratories, South Australian Research and Development Institute, Adelaide, SA, Australia
| | - Clive J McLaughlin
- Molecular Biology and Reproductive Technology, Laboratories, South Australian Research and Development Institute, Adelaide, SA, Australia
| | - C Simon Bawden
- Molecular Biology and Reproductive Technology, Laboratories, South Australian Research and Development Institute, Adelaide, SA, Australia
| | - Marcy E MacDonald
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Vanessa C Wheeler
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Russell G Snell
- Centre for Brain Research, School of Biological Sciences, The University of Auckland, Auckland, New Zealand
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Shing K, Sapp E, Boudi A, Liu S, Seeley C, Marchionini D, DiFiglia M, Kegel-Gleason KB. Early whole-body mutant huntingtin lowering averts changes in proteins and lipids important for synapse function and white matter maintenance in the LacQ140 mouse model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.26.525697. [PMID: 36747614 PMCID: PMC9900921 DOI: 10.1101/2023.01.26.525697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Expansion of a triplet repeat tract in exon1 of the HTT gene causes Huntington's disease (HD). The mutant HTT protein (mHTT) has numerous aberrant interactions with diverse, pleiomorphic effects. No disease modifying treatments exist but lowering mutant huntingtin (mHTT) by gene therapy is a promising approach to treat Huntington's disease (HD). It is not clear when lowering should be initiated, how much lowering is necessary and for what duration lowering should occur to achieve benefits. Furthermore, the effects of mHTT lowering on brain lipids have not been assessed. Using a mHtt-inducible mouse model we analyzed whole body mHtt lowering initiated at different ages and sustained for different time-periods. Subcellular fractionation (density gradient ultracentrifugation), protein chemistry (gel filtration, western blot, and capillary electrophoresis immunoassay), liquid chromatography and mass spectrometry of lipids, and bioinformatic approaches were used to test effects of mHTT transcriptional lowering. mHTT protein in cytoplasmic and synaptic compartments of the caudate putamen, which is most affected in HD, was reduced 38-52%. Little or no lowering of mHTT occurred in nuclear and perinuclear regions where aggregates formed at 12 months of age. mHtt transcript repression partially or fully preserved select striatal proteins (SCN4B, PDE10A). Total lipids in striatum were reduced in LacQ140 mice at 9 months and preserved by early partial mHtt lowering. The reduction in total lipids was due in part to reductions in subclasses of ceramide (Cer), sphingomyelin (SM), and monogalactosyldiacylglycerol (MGDG), which are known to be important for white matter structure and function. Lipid subclasses phosphatidylinositol (PI), phosphatidylserine (PS), and bismethyl phosphatidic acid (BisMePA) were also changed in LacQ140 mice. Levels of all subclasses other than ceramide were preserved by early mHtt lowering. Pathway enrichment analysis of RNAseq data imply a transcriptional mechanism is responsible in part for changes in myelin lipids, and some but not all changes can be rescued by mHTT lowering. Our findings suggest that early and sustained reduction in mHtt can prevent changes in levels of select striatal proteins and most lipids but a misfolded, degradation-resistant form of mHTT hampers some benefits in the long term.
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Affiliation(s)
- Kai Shing
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129
| | - Ellen Sapp
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129
| | - Adel Boudi
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129
| | - Sophia Liu
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129
| | - Connor Seeley
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129
| | | | - Marian DiFiglia
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129
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Sapp E, Boudi A, Reid SJ, Trombetta BA, Kivisäkk P, Taghian T, Arnold SE, Howland D, Gray-Edwards H, Kegel-Gleason KB, DiFiglia M. Levels of Synaptic Proteins in Brain and Neurofilament Light Chain in Cerebrospinal Fluid and Plasma of OVT73 Huntington's Disease Sheep Support a Prodromal Disease State. J Huntingtons Dis 2023; 12:201-213. [PMID: 37661892 DOI: 10.3233/jhd-230590] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
BACKGROUND Synaptic changes occur early in patients with Huntington's disease (HD) and in mouse models of HD. An analysis of synaptic changes in HD transgenic sheep (OVT73) is fitting since they have been shown to have some phenotypes. They also have larger brains, longer lifespan, and greater motor and cognitive capacities more aligned with humans, and can provide abundant biofluids for in vivo monitoring of therapeutic interventions. OBJECTIVE The objective of this study was to determine if there were differences between 5- and 10-year-old OVT73 and wild-type (WT) sheep in levels of synaptic proteins in brain and in neurofilament light chain (NfL) in cerebrospinal fluid (CSF) and plasma. METHODS Mutant huntingtin (mHTT) and other proteins were measured by western blot assay in synaptosomes prepared from caudate, motor, and piriform cortex in 5-year-old and caudate, putamen, motor; and piriform cortex in 10-year-old WT and OVT73 sheep. Levels of NfL, a biomarker for neuronal damage increased in many neurological disorders including HD, were examined in CSF and plasma samples from 10-year-old WT and OVT73 sheep using the Simoa NfL Advantage kit. RESULTS Western blot analysis showed mHTT protein expression in synaptosomes from OVT73 sheep was 23% of endogenous sheep HTT levels at both ages. Significant changes were detected in brain levels of PDE10A, SCN4B, DARPP32, calmodulin, SNAP25, PSD95, VGLUT 1, VAMP1, and Na+/K+-ATPase, which depended on age and brain region. There was no difference in NfL levels in CSF and plasma in OVT73 sheep compared to age-matched WT sheep. CONCLUSIONS These results show that synaptic changes occur in brain of 5- and 10-year-old OVT73 sheep, but levels of NfL in biofluids are unaffected. Altogether, the data support a prodromal disease state in OVT73 sheep that involves the caudate, putamen and cortex.
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Affiliation(s)
- Ellen Sapp
- Department of Neurology, Mass General Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Adel Boudi
- Department of Neurology, Mass General Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Suzanne J Reid
- Centre for Brain Research, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Bianca A Trombetta
- Department of Neurology, Alzheimer's Clinical and Translational Research Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Pia Kivisäkk
- Department of Neurology, Alzheimer's Clinical and Translational Research Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Toloo Taghian
- Department of Radiology and Horae Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Steven E Arnold
- Department of Neurology, Alzheimer's Clinical and Translational Research Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Heather Gray-Edwards
- Department of Radiology and Horae Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Kimberly B Kegel-Gleason
- Department of Neurology, Mass General Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Marian DiFiglia
- Department of Neurology, Mass General Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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Sun Y, Tong H, Yang T, Liu L, Li XJ, Li S. Insights into White Matter Defect in Huntington's Disease. Cells 2022; 11:3381. [PMID: 36359783 PMCID: PMC9656068 DOI: 10.3390/cells11213381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/21/2022] [Accepted: 10/21/2022] [Indexed: 08/05/2023] Open
Abstract
Huntington's disease (HD) is an autosomal-dominant inherited progressive neurodegenerative disorder. It is caused by a CAG repeat expansion in the Huntingtin gene that is translated to an expanded polyglutamine (PolyQ) repeat in huntingtin protein. HD is characterized by mood swings, involuntary movement, and cognitive decline in the late disease stage. HD patients often die 15-20 years after disease onset. Currently, there is no cure for HD. Due to the striking neuronal loss in HD, most studies focused on the investigation of the predominantly neuronal degeneration in specific brain regions. However, the pathology of the white matter area in the brains of HD patients was also reported by clinical imaging studies, which showed white matter abnormalities even before the clinical onset of HD. Since oligodendrocytes form myelin sheaths around the axons in the brain, white matter lesions are likely attributed to alterations in myelin and oligodendrocyte-associated changes in HD. In this review, we summarized the evidence for white matter, myelin, and oligodendrocytes alterations that were previously observed in HD patients and animal models. We also discussed potential mechanisms for white matter changes and possible treatment to prevent glial dysfunction in HD.
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