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Jarosińska OD, Rüdiger SGD. Molecular Strategies to Target Protein Aggregation in Huntington's Disease. Front Mol Biosci 2021; 8:769184. [PMID: 34869596 PMCID: PMC8636123 DOI: 10.3389/fmolb.2021.769184] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/18/2021] [Indexed: 11/30/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder caused by the aggregation of the mutant huntingtin (mHTT) protein in nerve cells. mHTT self-aggregates to form soluble oligomers and insoluble fibrils, which interfere in a number of key cellular functions. This leads to cell quiescence and ultimately cell death. There are currently still no treatments available for HD, but approaches targeting the HTT levels offer systematic, mechanism-driven routes towards curing HD and other neurodegenerative diseases. This review summarizes the current state of knowledge of the mRNA targeting approaches such as antisense oligonucleotides and RNAi system; and the novel methods targeting mHTT and aggregates for degradation via the ubiquitin proteasome or the autophagy-lysosomal systems. These methods include the proteolysis-targeting chimera, Trim-Away, autophagosome-tethering compound, autophagy-targeting chimera, lysosome-targeting chimera and approach targeting mHTT for chaperone-mediated autophagy. These molecular strategies provide a knowledge-based approach to target HD and other neurodegenerative diseases at the origin.
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Affiliation(s)
- Olga D. Jarosińska
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, Netherlands
- Science for Life, Utrecht University, Utrecht, Netherlands
| | - Stefan G. D. Rüdiger
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, Netherlands
- Science for Life, Utrecht University, Utrecht, Netherlands
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Haver HN, Scaglione KM. Dictyostelium discoideum as a Model for Investigating Neurodegenerative Diseases. Front Cell Neurosci 2021; 15:759532. [PMID: 34776869 PMCID: PMC8578527 DOI: 10.3389/fncel.2021.759532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/07/2021] [Indexed: 12/28/2022] Open
Abstract
The social amoeba Dictyostelium discoideum is a model organism that is used to investigate many cellular processes including chemotaxis, cell motility, cell differentiation, and human disease pathogenesis. While many single-cellular model systems lack homologs of human disease genes, Dictyostelium's genome encodes for many genes that are implicated in human diseases including neurodegenerative diseases. Due to its short doubling time along with the powerful genetic tools that enable rapid genetic screening, and the ease of creating knockout cell lines, Dictyostelium is an attractive model organism for both interrogating the normal function of genes implicated in neurodegeneration and for determining pathogenic mechanisms that cause disease. Here we review the literature involving the use of Dictyostelium to interrogate genes implicated in neurodegeneration and highlight key questions that can be addressed using Dictyostelium as a model organism.
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Affiliation(s)
- Holly N. Haver
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, United States
| | - K. Matthew Scaglione
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, United States
- Department of Neurology, Duke University, Durham, NC, United States
- Duke Center for Neurodegeneration and Neurotherapeutics, Duke University, Durham, NC, United States
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Pigazzini ML, Lawrenz M, Margineanu A, Kaminski Schierle GS, Kirstein J. An Expanded Polyproline Domain Maintains Mutant Huntingtin Soluble in vivo and During Aging. Front Mol Neurosci 2021; 14:721749. [PMID: 34720872 PMCID: PMC8554126 DOI: 10.3389/fnmol.2021.721749] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 08/30/2021] [Indexed: 02/02/2023] Open
Abstract
Huntington's disease is a dominantly inherited neurodegenerative disorder caused by the expansion of a CAG repeat, encoding for the amino acid glutamine (Q), present in the first exon of the protein huntingtin. Over the threshold of Q39 HTT exon 1 (HTTEx1) tends to misfold and aggregate into large intracellular structures, but whether these end-stage aggregates or their on-pathway intermediates are responsible for cytotoxicity is still debated. HTTEx1 can be separated into three domains: an N-terminal 17 amino acid region, the polyglutamine (polyQ) expansion and a C-terminal proline rich domain (PRD). Alongside the expanded polyQ, these flanking domains influence the aggregation propensity of HTTEx1: with the N17 initiating and promoting aggregation, and the PRD modulating it. In this study we focus on the first 11 amino acids of the PRD, a stretch of pure prolines, which are an evolutionary recent addition to the expanding polyQ region. We hypothesize that this proline region is expanding alongside the polyQ to counteract its ability to misfold and cause toxicity, and that expanding this proline region would be overall beneficial. We generated HTTEx1 mutants lacking both flanking domains singularly, missing the first 11 prolines of the PRD, or with this stretch of prolines expanded. We then followed their aggregation landscape in vitro with a battery of biochemical assays, and in vivo in novel models of C. elegans expressing the HTTEx1 mutants pan-neuronally. Employing fluorescence lifetime imaging we could observe the aggregation propensity of all HTTEx1 mutants during aging and correlate this with toxicity via various phenotypic assays. We found that the presence of an expanded proline stretch is beneficial in maintaining HTTEx1 soluble over time, regardless of polyQ length. However, the expanded prolines were only advantageous in promoting the survival and fitness of an organism carrying a pathogenic stretch of Q48 but were extremely deleterious to the nematode expressing a physiological stretch of Q23. Our results reveal the unique importance of the prolines which have and still are evolving alongside expanding glutamines to promote the function of HTTEx1 and avoid pathology.
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Affiliation(s)
- Maria Lucia Pigazzini
- Department of Molecular Physiology and Cell Biology, Leibniz Research Institute for Molecular Pharmacology in the Forschungsverbund Berlin e.V. (FMP), Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Mandy Lawrenz
- Department of Molecular Physiology and Cell Biology, Leibniz Research Institute for Molecular Pharmacology in the Forschungsverbund Berlin e.V. (FMP), Berlin, Germany
| | - Anca Margineanu
- Advanced Light Microscopy, Max-Delbrück Centrum for Molecular Medicine (MDC), Berlin, Germany
| | - Gabriele S. Kaminski Schierle
- Molecular Neuroscience Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | - Janine Kirstein
- Department of Molecular Physiology and Cell Biology, Leibniz Research Institute for Molecular Pharmacology in the Forschungsverbund Berlin e.V. (FMP), Berlin, Germany
- Department of Cell Biology, University of Bremen, Bremen, Germany
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Wang J, Cao H. Zebrafish and Medaka: Important Animal Models for Human Neurodegenerative Diseases. Int J Mol Sci 2021; 22:10766. [PMID: 34639106 PMCID: PMC8509648 DOI: 10.3390/ijms221910766] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 02/06/2023] Open
Abstract
Animal models of human neurodegenerative disease have been investigated for several decades. In recent years, zebrafish (Danio rerio) and medaka (Oryzias latipes) have become popular in pathogenic and therapeutic studies about human neurodegenerative diseases due to their small size, the optical clarity of embryos, their fast development, and their suitability to large-scale therapeutic screening. Following the emergence of a new generation of molecular biological technologies such as reverse and forward genetics, morpholino, transgenesis, and gene knockout, many human neurodegenerative disease models, such as Parkinson's, Huntington's, and Alzheimer's, were constructed in zebrafish and medaka. These studies proved that zebrafish and medaka genes are functionally conserved in relation to their human homologues, so they exhibit similar neurodegenerative phenotypes to human beings. Therefore, fish are a suitable model for the investigation of pathologic mechanisms of neurodegenerative diseases and for the large-scale screening of drugs for potential therapy. In this review, we summarize the studies in modelling human neurodegenerative diseases in zebrafish and medaka in recent years.
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Affiliation(s)
- Jing Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7#, Wuhan 430072, China;
- College of Advanced Agriculture Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong Cao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7#, Wuhan 430072, China;
- College of Advanced Agriculture Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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55
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Gusella JF, Lee JM, MacDonald ME. Huntington's disease: nearly four decades of human molecular genetics. Hum Mol Genet 2021; 30:R254-R263. [PMID: 34169318 PMCID: PMC8490011 DOI: 10.1093/hmg/ddab170] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 11/13/2022] Open
Abstract
Huntington's disease (HD) is a devastating neurogenetic disorder whose familial nature and progressive course were first described in the 19th century but for which no disease-modifying treatment is yet available. Through the active participation of HD families, this disorder has acted as a flagship for the application of human molecular genetic strategies to identify disease genes, understand pathogenesis and identify rational targets for development of therapies.
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Affiliation(s)
- James F Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Marcy E MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
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Fields E, Vaughan E, Tripu D, Lim I, Shrout K, Conway J, Salib N, Lee Y, Dhamsania A, Jacobsen M, Woo A, Xue H, Cao K. Gene targeting techniques for Huntington's disease. Ageing Res Rev 2021; 70:101385. [PMID: 34098113 PMCID: PMC8373677 DOI: 10.1016/j.arr.2021.101385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 05/24/2021] [Accepted: 06/03/2021] [Indexed: 02/08/2023]
Abstract
Huntington's disease (HD) is an autosomal neurodegenerative disorder caused by extended trinucleotide CAG repetition in the HTT gene. Wild-type huntingtin protein (HTT) is essential, involved in a variety of crucial cellular functions such as vesicle transportation, cell division, transcription regulation, autophagy, and tissue maintenance. The mutant HTT (mHTT) proteins in the body interfere with HTT's normal cellular functions and cause additional detrimental effects. In this review, we discuss multiple approaches targeting DNA and RNA to reduce mHTT expression. These approaches are categorized into non-allele-specific silencing and allele-specific-silencing using Single Nucleotide Polymorphisms (SNPs) and haplogroup analysis. Additionally, this review discusses a potential application of recent CRISPR prime editing technology in targeting HD.
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Affiliation(s)
- Eric Fields
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Erik Vaughan
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Deepika Tripu
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Isabelle Lim
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Katherine Shrout
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Jessica Conway
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Nicole Salib
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Yubin Lee
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Akash Dhamsania
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Michael Jacobsen
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Ashley Woo
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States
| | - Huijing Xue
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, United States
| | - Kan Cao
- Gemstone Honors Program, University of Maryland, College Park, MD 20742, United States; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, United States.
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Braatz EM, André EA, Liu JP, Zeitlin SO. Characterization of a Knock-In Mouse Model with a Huntingtin Exon 1 Deletion. J Huntingtons Dis 2021; 10:435-454. [PMID: 34459410 DOI: 10.3233/jhd-210494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND The Huntingtin (HTT) N-terminal domains encoded by Huntingtin's (HTT) exon 1 consist of an N17 domain, the polyglutamine (polyQ) stretch and a proline-rich region (PRR). These domains are conserved in mammals and have been hypothesized to modulate HTT's functions in the developing and adult CNS, including DNA damage repair and autophagy. OBJECTIVE This study longitudinally characterizes the in vivo consequences of deleting the murine Htt N-terminal domains encoded by Htt exon 1. METHODS Knock-in mice with a deletion of Htt exon 1 sequences (HttΔE1) were generated and bred into the C57BL/6J congenic genetic background. Their behavior, DNA damage response, basal autophagy, and glutamatergic synapse numbers were evaluated. RESULTS Progeny from HttΔE1/+ intercrosses are born at the expected Mendelian frequency but with a distorted male to female ratio in both the HttΔE1/ΔE1 and Htt+/+ offspring. HttΔE1/ΔE1 adults exhibit a modest deficit in accelerating rotarod performance, and an earlier increase in cortical and striatal DNA damage with elevated neuronal pan-nuclear 53bp1 levels compared to Htt+/+ mice. However, a normal response to induced DNA damage, normal levels of basal autophagy markers, and no significant differences in corticocortical, corticostriatal, thalamocortical, or thalamostriatal synapses numbers were observed compared to controls. CONCLUSION Our results suggest that deletion of the Htt N-terminus encoded by the Htt exon 1 does not affect Htt's critical role during embryogenesis, but instead, may have a modest effect on certain motor tasks, basal levels of DNA damage in the brain, and Htt function in the testis.
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Affiliation(s)
- Elise M Braatz
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Emily A André
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Jeh-Ping Liu
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Scott O Zeitlin
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
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Bensalel J, Xu H, Lu ML, Capobianco E, Wei J. RNA-seq analysis reveals significant transcriptome changes in huntingtin-null human neuroblastoma cells. BMC Med Genomics 2021; 14:176. [PMID: 34215255 PMCID: PMC8252266 DOI: 10.1186/s12920-021-01022-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 06/23/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Huntingtin (Htt) protein is the product of the gene mutated in Huntington's disease (HD), a fatal, autosomal dominant, neurodegenerative disorder. Normal Htt is essential for early embryogenesis and the development of the central nervous system. However, the role of Htt in adult tissues is less defined. Following the recent promising clinical trial in which both normal and mutant Htt mRNA were knocked down in HD patients, there is an urgent need to fully understand the molecular consequences of knocking out/down Htt in adult tissues. Htt has been identified as an important transcriptional regulator. Unbiased investigations of transcriptome changes with RNA-sequencing (RNA-Seq) have been done in multiple cell types in HD, further confirming that transcriptional dysregulation is a central pathogenic mechanism in HD. However, there is lack of direct understanding of the transcriptional regulation by normal Htt. METHODS To investigate the transcriptional role of normal Htt, we first knocked out Htt in the human neuroblastoma SH-SY5Y cell line using the CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 (CRISPR-associated protein 9) gene editing approach. We then performed RNA-seq analysis on Htt-null and wild type SH-SY5Y cells to probe the global transcriptome changes induced by Htt deletion. RESULTS In general, Htt has a widespread effect on gene transcription. Functional analysis of the differentially expressed genes (DEGs) using various bioinformatic tools revealed irregularities in pathways related to cell communication and signaling, and more specifically those related to neuron development, neurotransmission and synaptic signaling. We further examined the transcription factors that may regulate these DEGs. Consistent with the disrupted pathways associated with cellular development, we showed that Htt-null cells exhibited slower cell proliferation than wild type cells. We finally validated some of the top DEGS with quantitative RT-PCR. CONCLUSIONS The widespread transcriptome changes in Htt-null cells could be directly caused by the loss of Htt-mediated transcriptional regulation or due to the secondary consequences of disruption in the gene regulatory network. Our study therefore provides valuable information about key genes associated with Htt-mediated transcription and improves our understanding of the molecular mechanisms underlying the cellular functions of normal and mutant Htt.
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Affiliation(s)
- Johanna Bensalel
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, 33431, USA
| | - Hongyuan Xu
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, 33431, USA
| | - Michael L Lu
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, 33431, USA
| | - Enrico Capobianco
- Institute of Data Science and Computing, University of Miami, Miami, FL, 33146, USA
| | - Jianning Wei
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, 33431, USA.
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Barron JC, Hurley EP, Parsons MP. Huntingtin and the Synapse. Front Cell Neurosci 2021; 15:689332. [PMID: 34211373 PMCID: PMC8239291 DOI: 10.3389/fncel.2021.689332] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/24/2021] [Indexed: 12/16/2022] Open
Abstract
Huntington disease (HD) is a monogenic disease that results in a combination of motor, psychiatric and cognitive symptoms. HD is caused by a CAG trinucleotide repeat expansion in the huntingtin (HTT) gene, which results in the production of a pathogenic mutant HTT protein (mHTT). Although there is no cure at present for HD, a number of RNA-targeting therapies have recently entered clinical trials which aim to lower mHTT production through the use of antisense oligonucleotides (ASOs) and RNAi. However, many of these treatment strategies are non-selective in that they cannot differentiate between non-pathogenic wild type HTT (wtHTT) and the mHTT variant. As HD patients are already born with decreased levels of wtHTT, these genetic therapies may result in critically low levels of wtHTT. The consequence of wtHTT reduction in the adult brain is currently under debate, and here we argue that wtHTT loss is not well-tolerated at the synaptic level. Synaptic dysfunction is an extremely sensitive measure of subsequent cell death, and is known to precede neurodegeneration in numerous brain diseases including HD. The present review focuses on the prominent role of wtHTT at the synapse and considers the consequences of wtHTT loss on both pre- and postsynaptic function. We discuss how wtHTT is implicated in virtually all major facets of synaptic neurotransmission including anterograde and retrograde transport of proteins to/from terminal buttons and dendrites, neurotransmitter release, endocytic vesicle recycling, and postsynaptic receptor localization and recycling. We conclude that wtHTT presence is essential for proper synaptic function.
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Affiliation(s)
- Jessica C Barron
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Emily P Hurley
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Matthew P Parsons
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
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Caron NS, Anderson C, Black HF, Sanders SS, Lemarié FL, Doty CN, Hayden MR. Reliable Resolution of Full-Length Huntingtin Alleles by Quantitative Immunoblotting. J Huntingtons Dis 2021; 10:355-365. [PMID: 34092649 DOI: 10.3233/jhd-200463] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Therapeutics that lower mutant huntingtin (mHTT) have shown promise in preclinical studies and are in clinical development for the treatment of Huntington's disease (HD). Multiple assays have been developed that either quantify mHTT or total HTT but may not accurately measure levels of wild type HTT (wtHTT) in biological samples. OBJECTIVE To optimize a method that can be used to resolve, quantify and directly compare levels of full length wtHTT and mHTT in HD samples. METHODS We provide a detailed quantitative immunoblotting protocol to reproducibly resolve full length wtHTT and mHTT in multiple HD mouse and patient samples. RESULTS We show that this assay can be modified, depending on the sample, to resolve wtHTT and mHTT with a wide range of polyglutamine differences (ΔQs 22-179). We also demonstrate that this method can be used to quantify allele-selective lowering of mHTT using an antisense oligonucleotide in HD patient-derived cells. CONCLUSION This quantitative immunoblotting method can be used to reliably resolve full length HTT alleles with ΔQs≥22 and allows for direct comparison of wtHTT and mHTT levels in HD samples.
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Affiliation(s)
- Nicholas S Caron
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | | | - Hailey Findlay Black
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Shaun S Sanders
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.,Current address: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Fanny L Lemarié
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Crystal N Doty
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
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Hyeon JW, Kim AH, Yano H. Epigenetic regulation in Huntington's disease. Neurochem Int 2021; 148:105074. [PMID: 34038804 DOI: 10.1016/j.neuint.2021.105074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 04/23/2021] [Accepted: 05/17/2021] [Indexed: 12/25/2022]
Abstract
Huntington's disease (HD) is a devastating and fatal monogenic neurodegenerative disorder characterized by progressive loss of selective neurons in the brain and is caused by an abnormal expansion of CAG trinucleotide repeats in a coding exon of the huntingtin (HTT) gene. Progressive gene expression changes that begin at premanifest stages are a prominent feature of HD and are thought to contribute to disease progression. Increasing evidence suggests the critical involvement of epigenetic mechanisms in abnormal transcription in HD. Genome-wide alterations of a number of epigenetic modifications, including DNA methylation and multiple histone modifications, are associated with HD, suggesting that mutant HTT causes complex epigenetic abnormalities and chromatin structural changes, which may represent an underlying pathogenic mechanism. The causal relationship of specific epigenetic changes to early transcriptional alterations and to disease pathogenesis require further investigation. In this article, we review recent studies on epigenetic regulation in HD with a focus on DNA and histone modifications. We also discuss the contribution of epigenetic modifications to HD pathogenesis as well as potential mechanisms linking mutant HTT and epigenetic alterations. Finally, we discuss the therapeutic potential of epigenetic-based treatments.
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Affiliation(s)
- Jae Wook Hyeon
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Albert H Kim
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA; Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA; Department of Genetics, Washington University School of Medicine, St. Louis, MO, 63110, USA; Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hiroko Yano
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA; Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA; Department of Genetics, Washington University School of Medicine, St. Louis, MO, 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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Abstract
PURPOSE OF REVIEW Huntington's disease is a fatal autosomal dominant neurodegenerative disorder caused by a trinucleotide expansion in the HTT gene, and current therapies focus on symptomatic treatment. This review explores therapeutic approaches that directly target the pathogenic mutation, disrupt HTT mRNA or its translation. RECENT FINDINGS Zinc-finger transcription repressors and CRISPR-Cas9 therapies target HTT DNA, thereby preventing all downstream pathogenic mechanisms. These therapies, together with RNA interference (RNAi), require intraparenchymal delivery to the brain in viral vectors, with only a single delivery potentially required, though they may carry the risk of irreversible side-effects.Along with RNAi, antisense oligonucleotides (ASOs) target mRNA, but are delivered periodically and intrathecally. ASOs have safely decreased mutant huntingtin protein (mHTT) levels in the central nervous system of patients, and a phase 3 clinical trial is currently underway.Finally, orally available small molecules, acting on splicing or posttranslational modification, have recently been shown to decrease mHTT in animal models. SUMMARY Huntingtin-lowering approaches act upstream of pathogenic mechanisms and therefore have a high a priori likelihood of modifying disease course. ASOs are already in late-stage clinical development, whereas other strategies are progressing rapidly toward human studies.
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Ananbeh H, Vodicka P, Kupcova Skalnikova H. Emerging Roles of Exosomes in Huntington's Disease. Int J Mol Sci 2021; 22:ijms22084085. [PMID: 33920936 PMCID: PMC8071291 DOI: 10.3390/ijms22084085] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 02/07/2023] Open
Abstract
Huntington’s disease (HD) is a rare hereditary autosomal dominant neurodegenerative disorder, which is caused by expression of mutant huntingtin protein (mHTT) with an abnormal number of glutamine repeats in its N terminus, and characterized by intracellular mHTT aggregates (inclusions) in the brain. Exosomes are small extracellular vesicles that are secreted generally by all cell types and can be isolated from almost all body fluids such as blood, urine, saliva, and cerebrospinal fluid. Exosomes may participate in the spreading of toxic misfolded proteins across the central nervous system in neurodegenerative diseases. In HD, such propagation of mHTT was observed both in vitro and in vivo. On the other hand, exosomes might carry molecules with neuroprotective effects. In addition, due to their capability to cross blood-brain barrier, exosomes hold great potential as sources of biomarkers available from periphery or carriers of therapeutics into the central nervous system. In this review, we discuss the emerging roles of exosomes in HD pathogenesis, diagnosis, and therapy.
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Burrus CJ, McKinstry SU, Kim N, Ozlu MI, Santoki AV, Fang FY, Ma A, Karadeniz YB, Worthington AK, Dragatsis I, Zeitlin S, Yin HH, Eroglu C. Striatal Projection Neurons Require Huntingtin for Synaptic Connectivity and Survival. Cell Rep 2021; 30:642-657.e6. [PMID: 31968243 DOI: 10.1016/j.celrep.2019.12.069] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 11/07/2019] [Accepted: 12/17/2019] [Indexed: 12/19/2022] Open
Abstract
Huntington's disease (HD) is caused by an autosomal dominant polyglutamine expansion mutation of Huntingtin (HTT). HD patients suffer from progressive motor, cognitive, and psychiatric impairments, along with significant degeneration of the striatal projection neurons (SPNs) of the striatum. HD is widely accepted to be caused by a toxic gain-of-function of mutant HTT. However, whether loss of HTT function, because of dominant-negative effects of the mutant protein, plays a role in HD and whether HTT is required for SPN health and function are not known. Here, we delete Htt from specific subpopulations of SPNs using the Cre-Lox system and find that SPNs require HTT for motor regulation, synaptic development, cell health, and survival during aging. Our results suggest that loss of HTT function in SPNs could play a critical role in HD pathogenesis.
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Affiliation(s)
- Caley J Burrus
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Spencer U McKinstry
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Namsoo Kim
- Department of Psychology and Neuroscience, Trinity College of Arts and Sciences, Duke University, Durham, NC 27710, USA
| | - M Ilcim Ozlu
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Aditya V Santoki
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Francia Y Fang
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Annie Ma
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Yonca B Karadeniz
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Atesh K Worthington
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ioannis Dragatsis
- Department of Physiology, The University of Tennessee, Health Science Center, Memphis, TN 38163, USA
| | - Scott Zeitlin
- Department of Neuroscience, University of Virginia, School of Medicine, Charlottesville, VA 22908, USA
| | - Henry H Yin
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Psychology and Neuroscience, Trinity College of Arts and Sciences, Duke University, Durham, NC 27710, USA; Duke Institute for Brain Sciences, Durham, NC 27710, USA
| | - Cagla Eroglu
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA; Duke Institute for Brain Sciences, Durham, NC 27710, USA; Regeneration Next Initiative, Duke University, Durham, NC 27710, USA.
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65
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Lu S, Lu B. Degeneration Versus Development: Hunting-Out the D-Unit of Huntington's Disease. Neurosci Bull 2021; 37:757-760. [PMID: 33721179 DOI: 10.1007/s12264-021-00649-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 10/26/2020] [Indexed: 10/21/2022] Open
Affiliation(s)
- Shengyi Lu
- State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, School of Life Sciences, Fudan University, Shanghai, 200032, China
| | - Boxun Lu
- State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, School of Life Sciences, Fudan University, Shanghai, 200032, China.
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66
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Wang XT, Sun H, Chen NH, Yuan YH. Tunneling nanotubes: A novel pharmacological target for neurodegenerative diseases? Pharmacol Res 2021; 170:105541. [PMID: 33711434 DOI: 10.1016/j.phrs.2021.105541] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/06/2021] [Accepted: 03/07/2021] [Indexed: 12/25/2022]
Abstract
Diversiform ways of intercellular communication are vital links in maintaining homeostasis and disseminating physiological states. Among intercellular bridges, tunneling nanotubes (TNTs) discovered in 2004 were recognized as potential pharmacology targets related to the pathogenesis of common or infrequent neurodegenerative disorders. The neurotoxic aggregates in neurodegenerative diseases including scrapie prion protein (PrPSc), mutant tau protein, amyloid-beta (Aβ) protein, alpha-synuclein (α-syn) as well as mutant Huntington (mHTT) protein could promote TNT formation via certain physiological mechanisms, in turn, mediating the intercellular transmission of neurotoxicity. In this review, we described in detail the skeleton, the formation, the physicochemical properties, and the functions of TNTs, while paying particular attention to the key role of TNTs in the transport of pathological proteins during neurodegeneration.
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Affiliation(s)
- Xiao-Tong Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica& Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
| | - Hua Sun
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica& Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China; NHC Key Laboratory of Drug Addiction Medicine, The First Affiliated Hospital of Kunming Medical University, Kunming, China.
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica& Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
| | - Yu-He Yuan
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica& Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
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67
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Eshraghi M, Karunadharma PP, Blin J, Shahani N, Ricci EP, Michel A, Urban NT, Galli N, Sharma M, Ramírez-Jarquín UN, Florescu K, Hernandez J, Subramaniam S. Mutant Huntingtin stalls ribosomes and represses protein synthesis in a cellular model of Huntington disease. Nat Commun 2021; 12:1461. [PMID: 33674575 PMCID: PMC7935949 DOI: 10.1038/s41467-021-21637-y] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 01/29/2021] [Indexed: 02/08/2023] Open
Abstract
The polyglutamine expansion of huntingtin (mHTT) causes Huntington disease (HD) and neurodegeneration, but the mechanisms remain unclear. Here, we found that mHtt promotes ribosome stalling and suppresses protein synthesis in mouse HD striatal neuronal cells. Depletion of mHtt enhances protein synthesis and increases the speed of ribosomal translocation, while mHtt directly inhibits protein synthesis in vitro. Fmrp, a known regulator of ribosome stalling, is upregulated in HD, but its depletion has no discernible effect on protein synthesis or ribosome stalling in HD cells. We found interactions of ribosomal proteins and translating ribosomes with mHtt. High-resolution global ribosome footprint profiling (Ribo-Seq) and mRNA-Seq indicates a widespread shift in ribosome occupancy toward the 5' and 3' end and unique single-codon pauses on selected mRNA targets in HD cells, compared to controls. Thus, mHtt impedes ribosomal translocation during translation elongation, a mechanistic defect that can be exploited for HD therapeutics.
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Affiliation(s)
- Mehdi Eshraghi
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Pabalu P. Karunadharma
- grid.214007.00000000122199231The Scripps Research Institute, Genomic Core, Jupiter, FL USA
| | - Juliana Blin
- grid.462957.b0000 0004 0598 0706Laboratory of Biology and Cellular Modelling at Ecole Normale Supérieure of Lyon, RNA Metabolism in Immunity and Infection Lab, LBMC, Lyon, France
| | - Neelam Shahani
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Emiliano P. Ricci
- grid.462957.b0000 0004 0598 0706Laboratory of Biology and Cellular Modelling at Ecole Normale Supérieure of Lyon, RNA Metabolism in Immunity and Infection Lab, LBMC, Lyon, France
| | | | | | - Nicole Galli
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Manish Sharma
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Uri Nimrod Ramírez-Jarquín
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Katie Florescu
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Jennifer Hernandez
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
| | - Srinivasa Subramaniam
- grid.214007.00000000122199231The Scripps Research Institute, Department of Neuroscience, Jupiter, FL USA
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68
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Hickman RA, Faust PL, Rosenblum MK, Marder K, Mehler MF, Vonsattel JP. Developmental malformations in Huntington disease: neuropathologic evidence of focal neuronal migration defects in a subset of adult brains. Acta Neuropathol 2021; 141:399-413. [PMID: 33517535 PMCID: PMC7882590 DOI: 10.1007/s00401-021-02269-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/27/2020] [Accepted: 01/19/2021] [Indexed: 12/14/2022]
Abstract
Neuropathologic hallmarks of Huntington Disease (HD) include the progressive neurodegeneration of the striatum and the presence of Huntingtin (HTT) aggregates that result from abnormal polyQ expansion of the HTT gene. Whether the pathogenic trinucleotide repeat expansion of the HTT gene causes neurodevelopmental abnormalities has garnered attention in both murine and human studies; however, documentation of discrete malformations in autopsy brains of HD individuals has yet to be described. We retrospectively searched the New York Brain Bank (discovery cohort) and an independent cohort (validation cohort) to determine whether developmental malformations are more frequently detected in HD versus non-HD brains and to document their neuropathologic features. One-hundred and thirty HD and 1600 non-HD whole brains were included in the discovery cohort and 720 HD and 1989 non-HD half brains were assessed in the validation cohort. Cases with developmental malformations were found at 6.4–8.2 times greater frequency in HD than in non-HD brains (discovery cohort: OR 8.68, 95% CI 3.48–21.63, P=4.8 × 10-5; validation cohort: OR 6.50, 95% CI 1.83–23.17, P=0.0050). Periventricular nodular heterotopias (PNH) were the most frequent malformations and contained HTT and p62 aggregates analogous to the cortex, whereas cortical malformations with immature neuronal populations did not harbor such inclusions. HD individuals with malformations had heterozygous HTT CAG expansions between 40 and 52 repeats, were more frequently women, and all were asymmetric and focal, aside from one midline hypothalamic hamartoma. Using two independent brain bank cohorts, this large neuropathologic series demonstrates an increased occurrence of developmental malformations in HD brains. Since pathogenic HTT gene expansion is associated with genomic instability, one possible explanation is that neuronal precursors are more susceptible to somatic mutation of genes involved in cortical migration. Our findings further support emerging evidence that pathogenic trinucleotide repeat expansions of the HTT gene may impact neurodevelopment.
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Affiliation(s)
- R A Hickman
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and New York Presbyterian Hospital, New York, USA.
| | - P L Faust
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and New York Presbyterian Hospital, New York, USA
| | - M K Rosenblum
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, USA
| | - K Marder
- Department of Neurology and Psychiatry, Columbia University Irving Medical Center, New York, USA
- Taub Institute for Research on Alzheimer's disease and the Aging Brain, Columbia University Medical Center, 710 West 168th Street, New York, NY, 10032, USA
| | - M F Mehler
- The Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, New York, USA
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, USA
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, New York, USA
| | - J P Vonsattel
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and New York Presbyterian Hospital, New York, USA
- Taub Institute for Research on Alzheimer's disease and the Aging Brain, Columbia University Medical Center, 710 West 168th Street, New York, NY, 10032, USA
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69
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Leavitt BR, Kordasiewicz HB, Schobel SA. Huntingtin-Lowering Therapies for Huntington Disease: A Review of the Evidence of Potential Benefits and Risks. JAMA Neurol 2021; 77:764-772. [PMID: 32202594 DOI: 10.1001/jamaneurol.2020.0299] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Huntington disease (HD) is caused by a cytosine-adenine-guanine trinucleotide repeat expansion in the huntingtin gene, HTT, that results in expression of variant (mutant) huntingtin protein (HTT). Therapeutic strategies that reduce HTT levels are currently being pursued to slow or stop disease progression in people with HD. These approaches are supported by robust preclinical data indicating that reducing variant huntingtin protein is associated with decreased HD pathology. However, the risk-benefit profile of reducing either variant HTT or both variant and wild-type HTT is currently an open question that is being addressed in ongoing clinical trials. This review aims to examine the current data available regarding altered HTT in humans, normal animals, and animal models of HD. Studies indexed in PubMed were searched using the MeSH term Huntington disease or the text words huntington or huntingtin from August 31, 1999, to August 31, 2019, with no language restrictions. Additional studies were included from the reference lists of relevant studies and the authors' personal files. Articles describing at least 1 aspect of HTT reduction were included, prioritizing those published within the last 10 years. In vivo studies were also prioritized, with a focus on studies that examined the consequences of wild-type HTT reduction in adults. In a recently completed phase 1/2a study of RG6042 in 46 adults with early manifest HD, antisense oligonucleotide-mediated partial reduction of HTT was reported to be generally safe and well tolerated over the course of 4-monthly RG6042 doses. In case studies of people with rare genetic variations in huntingtin alleles, the loss of 1 wild-type allele was not associated with HD. People with homozygous cytosine-adenine-guanine expansions developed normally until the onset of HD, although they may have experienced a more aggressive disease course. In mouse models of HD, partial reduction of HTT was beneficial, with improvements in motor, cognitive, and behavioral phenotypes. The partial reduction of wild-type HTT in normal adult rodents and nonhuman primates was generally safe and well tolerated. The body of evidence reviewed in this article indicates a positive risk-benefit profile for the partial reduction of either variant HTT alone or both variant and wild-type HTT. These strategies target the underlying cause of HD and are currently being tested in several investigational clinical trials.
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Affiliation(s)
- Blair R Leavitt
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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70
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Ravi B, Chan-Cortés MH, Sumner CJ. Gene-Targeting Therapeutics for Neurological Disease: Lessons Learned from Spinal Muscular Atrophy. Annu Rev Med 2021; 72:1-14. [PMID: 33502897 DOI: 10.1146/annurev-med-070119-115459] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The last few decades have seen an explosion in identification of genes that cause monogenetic neurological diseases, as well as advances in gene-targeting therapeutics. Neurological conditions that were once considered incurable are now increasingly tractable. At the forefront is the motor neuron disease spinal muscular atrophy (SMA), historically the leading inherited cause of infant mortality. In the last 5 years, three SMA treatments have been approved by the US Food and Drug Administration (FDA): intrathecally delivered splice-switching antisense oligonucleotide (nusinersen), systemically delivered AAV9-based gene replacement therapy (onasemnogene abeparvovec), and an orally bioavailable, small-molecule, splice-switching drug (risdiplam). Despite this remarkable progress, clinical outcomes in patients are variable. Therapeutic optimization will require improved understanding of drug pharmacokinetics and target engagement in neurons, potential toxicities, and long-term effects. We review current progress in SMA therapeutics, clinical trials, shortcomings of current treatments, and implications for the treatment of other neurogenetic diseases.
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Affiliation(s)
- Bhavya Ravi
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;
| | | | - Charlotte J Sumner
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA; .,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21202, USA
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71
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Jung R, Lee Y, Barker D, Correia K, Shin B, Loupe J, Collins RL, Lucente D, Ruliera J, Gillis T, Mysore JS, Rodan L, Picker J, Lee JM, Howland D, Lee R, Kwak S, MacDonald ME, Gusella JF, Seong IS. Mutations causing Lopes-Maciel-Rodan syndrome are huntingtin hypomorphs. Hum Mol Genet 2021; 30:135-148. [PMID: 33432339 DOI: 10.1093/hmg/ddaa283] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 11/18/2020] [Accepted: 12/24/2020] [Indexed: 12/31/2022] Open
Abstract
Huntington's disease pathogenesis involves a genetic gain-of-function toxicity mechanism triggered by the expanded HTT CAG repeat. Current therapeutic efforts aim to suppress expression of total or mutant huntingtin, though the relationship of huntingtin's normal activities to the gain-of-function mechanism and what the effects of huntingtin-lowering might be are unclear. Here, we have re-investigated a rare family segregating two presumed HTT loss-of-function (LoF) variants associated with the developmental disorder, Lopes-Maciel-Rodan syndrome (LOMARS), using whole-genome sequencing of DNA from cell lines, in conjunction with analysis of mRNA and protein expression. Our findings correct the muddled annotation of these HTT variants, reaffirm they are the genetic cause of the LOMARS phenotype and demonstrate that each variant is a huntingtin hypomorphic mutation. The NM_002111.8: c.4469+1G>A splice donor variant results in aberrant (exon 34) splicing and severely reduced mRNA, whereas, surprisingly, the NM_002111.8: c.8157T>A NP_002102.4: Phe2719Leu missense variant results in abnormally rapid turnover of the Leu2719 huntingtin protein. Thus, although rare and subject to an as yet unknown LoF intolerance at the population level, bona fide HTT LoF variants can be transmitted by normal individuals leading to severe consequences in compound heterozygotes due to huntingtin deficiency.
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Affiliation(s)
- Roy Jung
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Yejin Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Douglas Barker
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Baehyun Shin
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Jacob Loupe
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Ryan L Collins
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA.,Program in Bioinformatics and Integrative Genomics, Division of Medical Sciences, Harvard Medical School, Boston, MA 02114, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Jayla Ruliera
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Jayalakshmi S Mysore
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Lance Rodan
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Neurology, Boston Children's Hospital, Harvard Medical School, MA 02115, USA
| | - Jonathan Picker
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Child and Adolescent Psychiatry, Boston Children's Hospital, Harvard Medical School, MA 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - David Howland
- CHDI Management/CHDI Foundation Inc., Princeton, NJ 08540, USA
| | - Ramee Lee
- CHDI Management/CHDI Foundation Inc., Princeton, NJ 08540, USA
| | - Seung Kwak
- CHDI Management/CHDI Foundation Inc., Princeton, NJ 08540, USA
| | - Marcy E MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA.,Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - James F Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA.,Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Ihn Sik Seong
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
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72
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Seefelder M, Alva V, Huang B, Engler T, Baumeister W, Guo Q, Fernández-Busnadiego R, Lupas AN, Kochanek S. The evolution of the huntingtin-associated protein 40 (HAP40) in conjunction with huntingtin. BMC Evol Biol 2020; 20:162. [PMID: 33297953 PMCID: PMC7725122 DOI: 10.1186/s12862-020-01705-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 10/20/2020] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The huntingtin-associated protein 40 (HAP40) abundantly interacts with huntingtin (HTT), the protein that is altered in Huntington's disease (HD). Therefore, we analysed the evolution of HAP40 and its interaction with HTT. RESULTS We found that in amniotes HAP40 is encoded by a single-exon gene, whereas in all other organisms it is expressed from multi-exon genes. HAP40 co-occurs with HTT in unikonts, including filastereans such as Capsaspora owczarzaki and the amoebozoan Dictyostelium discoideum, but both proteins are absent from fungi. Outside unikonts, a few species, such as the free-living amoeboflagellate Naegleria gruberi, contain putative HTT and HAP40 orthologs. Biochemically we show that the interaction between HTT and HAP40 extends to fish, and bioinformatic analyses provide evidence for evolutionary conservation of this interaction. The closest homologue of HAP40 in current protein databases is the family of soluble N-ethylmaleimide-sensitive factor attachment proteins (SNAPs). CONCLUSION Our results indicate that the transition from a multi-exon to a single-exon gene appears to have taken place by retroposition during the divergence of amphibians and amniotes, followed by the loss of the parental multi-exon gene. Furthermore, it appears that the two proteins probably originated at the root of eukaryotes. Conservation of the interaction between HAP40 and HTT and their likely coevolution strongly indicate functional importance of this interaction.
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Affiliation(s)
| | - Vikram Alva
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076, Tübingen, Germany
| | - Bin Huang
- Department of Gene Therapy, Ulm University, 89081, Ulm, Germany
| | - Tatjana Engler
- Department of Gene Therapy, Ulm University, 89081, Ulm, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Qiang Guo
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
- Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, 100871, China
| | - Rubén Fernández-Busnadiego
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
- Institute of Neuropathology, University Medical Center Göttingen, 37099, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines To Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Andrei N Lupas
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076, Tübingen, Germany.
| | - Stefan Kochanek
- Department of Gene Therapy, Ulm University, 89081, Ulm, Germany.
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73
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Colpo GD, Rocha NP, Furr Stimming E, Teixeira AL. Gene Expression Profiling in Huntington's Disease: Does Comorbidity with Depressive Symptoms Matter? Int J Mol Sci 2020; 21:E8474. [PMID: 33187165 PMCID: PMC7697115 DOI: 10.3390/ijms21228474] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/28/2020] [Accepted: 11/09/2020] [Indexed: 12/11/2022] Open
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disease. Besides the well-characterized motor symptoms, HD is marked by cognitive impairment and behavioral changes. In this study, we analyzed the blood of HD gene carries using RNA-sequencing techniques. We evaluated samples from HD gene carriers with (n = 8) and without clinically meaningful depressive symptoms (n = 8) compared with healthy controls (n = 8). Groups were age- and sex-matched. Preprocessing of data and between-group comparisons were calculated using DESeq2. The Wald test was used to generate p-values and log2 fold changes. We found 60 genes differently expressed in HD and healthy controls, of which 21 were upregulated and 39 downregulated. Within HD group, nineteen genes were differently expressed between patients with and without depression, being 6 upregulated and 13 downregulated. Several of the top differentially expressed genes are involved in nervous system development. Although preliminary, our findings corroborate the emerging view that in addition to neurodegenerative mechanisms, HD has a neurodevelopmental component. Importantly, the emergence of depression in HD might be related to these mechanisms.
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Affiliation(s)
- Gabriela Delevati Colpo
- Neuropsychiatry Program, Louis A Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA;
| | - Natalia Pessoa Rocha
- HDSA Center of Excellence at The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (N.P.R.); (E.F.S.)
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Erin Furr Stimming
- HDSA Center of Excellence at The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (N.P.R.); (E.F.S.)
- Department of Neurology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Antonio Lucio Teixeira
- Neuropsychiatry Program, Louis A Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA;
- HDSA Center of Excellence at The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (N.P.R.); (E.F.S.)
- Instituto de Ensino & Pesquisa, Santa Casa BH, Belo Horizonte 30150-221, Brazil
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74
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Bozzi M, Sciandra F. Molecular Mechanisms Underlying Muscle Wasting in Huntington's Disease. Int J Mol Sci 2020; 21:ijms21218314. [PMID: 33167595 PMCID: PMC7664236 DOI: 10.3390/ijms21218314] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/03/2020] [Accepted: 11/03/2020] [Indexed: 12/13/2022] Open
Abstract
Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by pathogenic expansions of the triplet cytosine-adenosine-guanosine (CAG) within the Huntingtin gene. These expansions lead to a prolongation of the poly-glutamine stretch at the N-terminus of Huntingtin causing protein misfolding and aggregation. Huntingtin and its pathological variants are widely expressed, but the central nervous system is mainly affected, as proved by the wide spectrum of neurological symptoms, including behavioral anomalies, cognitive decline and motor disorders. Other hallmarks of HD are loss of body weight and muscle atrophy. This review highlights some key elements that likely provide a major contribution to muscle atrophy, namely, alteration of the transcriptional processes, mitochondrial dysfunction, which is strictly correlated to loss of energy homeostasis, inflammation, apoptosis and defects in the processes responsible for the protein quality control. The improvement of muscular symptoms has proven to slow the disease progression and extend the life span of animal models of HD, underlining the importance of a deep comprehension of the molecular mechanisms driving deterioration of muscular tissue.
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Affiliation(s)
- Manuela Bozzi
- Dipartimento Universitario di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Sezione di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore di Roma, Largo F. Vito 1, 00168 Roma, Italy
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”– SCITEC Sede di Roma, Largo F. Vito 1, 00168 Roma, Italy;
- Correspondence:
| | - Francesca Sciandra
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”– SCITEC Sede di Roma, Largo F. Vito 1, 00168 Roma, Italy;
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75
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Overhoff M, De Bruyckere E, Kononenko NL. Mechanisms of neuronal survival safeguarded by endocytosis and autophagy. J Neurochem 2020; 157:263-296. [PMID: 32964462 DOI: 10.1111/jnc.15194] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/21/2020] [Accepted: 09/08/2020] [Indexed: 12/11/2022]
Abstract
Multiple aspects of neuronal physiology crucially depend on two cellular pathways, autophagy and endocytosis. During endocytosis, extracellular components either unbound or recognized by membrane-localized receptors (termed "cargo") become internalized into plasma membrane-derived vesicles. These can serve to either recycle the material back to the plasma membrane or send it for degradation to lysosomes. Autophagy also uses lysosomes as a terminal degradation point, although instead of degrading the plasma membrane-derived cargo, autophagy eliminates detrimental cytosolic material and intracellular organelles, which are transported to lysosomes by means of double-membrane vesicles, referred to as autophagosomes. Neurons, like all non-neuronal cells, capitalize on autophagy and endocytosis to communicate with the environment and maintain protein and organelle homeostasis. Additionally, the highly polarized, post-mitotic nature of neurons made them adopt these two pathways for cell-specific functions. These include the maintenance of the synaptic vesicle pool in the pre-synaptic terminal and the long-distance transport of signaling molecules. Originally discovered independently from each other, it is now clear that autophagy and endocytosis are closely interconnected and share several common participating molecules. Considering the crucial role of autophagy and endocytosis in cell type-specific functions in neurons, it is not surprising that defects in both pathways have been linked to the pathology of numerous neurodegenerative diseases. In this review, we highlight the recent knowledge of the role of endocytosis and autophagy in neurons with a special focus on synaptic physiology and discuss how impairments in genes coding for autophagy and endocytosis proteins can cause neurodegeneration.
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Affiliation(s)
- Melina Overhoff
- CECAD Cluster of Excellence, Institute for Genetics, University of Cologne, Cologne, Germany
| | - Elodie De Bruyckere
- CECAD Cluster of Excellence, Institute for Genetics, University of Cologne, Cologne, Germany
| | - Natalia L Kononenko
- CECAD Cluster of Excellence, Institute for Genetics, University of Cologne, Cologne, Germany
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76
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O'Regan GC, Farag SH, Ostroff GR, Tabrizi SJ, Andre R. Wild-type huntingtin regulates human macrophage function. Sci Rep 2020; 10:17269. [PMID: 33057179 PMCID: PMC7560844 DOI: 10.1038/s41598-020-74042-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 09/17/2020] [Indexed: 01/07/2023] Open
Abstract
The huntingtin (HTT) protein in its mutant form is the cause of the inherited neurodegenerative disorder, Huntington's disease. Beyond its effects in the central nervous system, disease-associated mutant HTT causes aberrant phenotypes in myeloid-lineage innate immune system cells, namely monocytes and macrophages. Whether the wild-type form of the protein, however, has a role in normal human macrophage function has not been determined. Here, the effects of lowering the expression of wild-type (wt)HTT on the function of primary monocyte-derived macrophages from healthy, non-disease human subjects were examined. This demonstrated a previously undescribed role for wtHTT in maintaining normal macrophage health and function. Lowered wtHTT expression was associated, for instance, with a diminished release of induced cytokines, elevated phagocytosis and increased vulnerability to cellular stress. These may well occur by mechanisms different to that associated with the mutant form of the protein, given an absence of any effect on the intracellular signalling pathway predominantly associated with macrophage dysfunction in Huntington's disease.
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Affiliation(s)
- Grace C O'Regan
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Sahar H Farag
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Gary R Ostroff
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Two Biotech, Suite 113, Worcester, MA, 01605, USA
| | - Sarah J Tabrizi
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. .,UK Dementia Research Institute at UCL, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.
| | - Ralph Andre
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.
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77
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Svrzikapa N, Longo KA, Prasad N, Boyanapalli R, Brown JM, Dorset D, Yourstone S, Powers J, Levy SE, Morris AJ, Vargeese C, Goyal J. Investigational Assay for Haplotype Phasing of the Huntingtin Gene. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 19:162-173. [PMID: 33209959 PMCID: PMC7648085 DOI: 10.1016/j.omtm.2020.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 09/04/2020] [Indexed: 01/20/2023]
Abstract
Novel treatments for Huntington's disease (HD), a progressive neurodegenerative disorder, include selective targeting of the mutant allele of the huntingtin gene (mHTT) carrying the abnormally expanded disease-causing cytosine-adenine-guanine (CAG) repeat. WVE-120101 and WVE-120102 are investigational stereopure antisense oligonucleotides that enable selective suppression of mHTT by targeting single-nucleotide polymorphisms (SNPs) that are in haplotype phase with the CAG repeat expansion. Recently developed long-read sequencing technologies can capture CAG expansions and distant SNPs of interest and potentially facilitate haplotype-based identification of patients for clinical trials of oligonucleotide therapies. However, improved methods are needed to phase SNPs with CAG repeat expansions directly and reliably without need for familial genotype/haplotype data. Our haplotype phasing method uses single-molecule real-time sequencing and a custom algorithm to determine with confidence bases at SNPs on mutant alleles, even without familial data. Herein, we summarize this methodology and validate the approach using patient-derived samples with known phasing results. Comparison of experimentally measured CAG repeat lengths, heterozygosity, and phasing with previously determined results showed improved performance. Our methodology enables the haplotype phasing of SNPs of interest and the disease-causing, expanded CAG repeat of the huntingtin gene, enabling accurate identification of patients with HD eligible for allele-selective clinical studies.
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Affiliation(s)
- Nenad Svrzikapa
- Wave Life Sciences Ltd., Cambridge, MA 02138, USA.,Department of Paediatrics, Medical Sciences Division, University of Oxford, Oxford OX3 9DU, UK
| | | | - Nripesh Prasad
- HudsonAlpha Discovery, Discovery Life Sciences, Huntsville, AL 35806, USA.,Genomic Services Laboratory, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | | | | | - Daniel Dorset
- HudsonAlpha Discovery, Discovery Life Sciences, Huntsville, AL 35806, USA.,Genomic Services Laboratory, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | | | - Jason Powers
- Q Solutions
- EA Genomics, LLC, Morrisville, NC 27560, USA
| | - Shawn E Levy
- HudsonAlpha Discovery, Discovery Life Sciences, Huntsville, AL 35806, USA.,Genomic Services Laboratory, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | | | | | - Jaya Goyal
- Wave Life Sciences Ltd., Cambridge, MA 02138, USA
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78
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Lebouc M, Richard Q, Garret M, Baufreton J. Striatal circuit development and its alterations in Huntington's disease. Neurobiol Dis 2020; 145:105076. [PMID: 32898646 DOI: 10.1016/j.nbd.2020.105076] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/26/2020] [Accepted: 09/02/2020] [Indexed: 12/23/2022] Open
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder that usually starts during midlife with progressive alterations of motor and cognitive functions. The disease is caused by a CAG repeat expansion within the huntingtin gene leading to severe striatal neurodegeneration. Recent studies conducted on pre-HD children highlight early striatal developmental alterations starting as soon as 6 years old, the earliest age assessed. These findings, in line with data from mouse models of HD, raise the questions of when during development do the first disease-related striatal alterations emerge and whether they contribute to the later appearance of the neurodegenerative features of the disease. In this review we will describe the different stages of striatal network development and then discuss recent evidence for its alterations in rodent models of the disease. We argue that a better understanding of the striatum's development should help in assessing aberrant neurodevelopmental processes linked to the HD mutation.
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Affiliation(s)
- Margaux Lebouc
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Quentin Richard
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Maurice Garret
- Université de Bordeaux, Institut des Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, F-33000 Bordeaux, France; CNRS, Institut des Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, F-33000 Bordeaux, France.
| | - Jérôme Baufreton
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France.
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79
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Tabrizi SJ, Flower MD, Ross CA, Wild EJ. Huntington disease: new insights into molecular pathogenesis and therapeutic opportunities. Nat Rev Neurol 2020; 16:529-546. [PMID: 32796930 DOI: 10.1038/s41582-020-0389-4] [Citation(s) in RCA: 240] [Impact Index Per Article: 60.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/29/2020] [Indexed: 12/11/2022]
Abstract
Huntington disease (HD) is a neurodegenerative disease caused by CAG repeat expansion in the huntingtin gene (HTT) and involves a complex web of pathogenic mechanisms. Mutant HTT (mHTT) disrupts transcription, interferes with immune and mitochondrial function, and is aberrantly modified post-translationally. Evidence suggests that the mHTT RNA is toxic, and at the DNA level, somatic CAG repeat expansion in vulnerable cells influences the disease course. Genome-wide association studies have identified DNA repair pathways as modifiers of somatic instability and disease course in HD and other repeat expansion diseases. In animal models of HD, nucleocytoplasmic transport is disrupted and its restoration is neuroprotective. Novel cerebrospinal fluid (CSF) and plasma biomarkers are among the earliest detectable changes in individuals with premanifest HD and have the sensitivity to detect therapeutic benefit. Therapeutically, the first human trial of an HTT-lowering antisense oligonucleotide successfully, and safely, reduced the CSF concentration of mHTT in individuals with HD. A larger trial, powered to detect clinical efficacy, is underway, along with trials of other HTT-lowering approaches. In this Review, we discuss new insights into the molecular pathogenesis of HD and future therapeutic strategies, including the modulation of DNA repair and targeting the DNA mutation itself.
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Affiliation(s)
- Sarah J Tabrizi
- Huntington's Disease Centre, University College London, London, UK. .,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, London, UK. .,UK Dementia Research Institute, University College London, London, UK.
| | - Michael D Flower
- Huntington's Disease Centre, University College London, London, UK.,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, London, UK.,UK Dementia Research Institute, University College London, London, UK
| | - Christopher A Ross
- Departments of Neurology, Neuroscience and Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Edward J Wild
- Huntington's Disease Centre, University College London, London, UK.,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, London, UK
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80
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Proteotoxicity and Neurodegenerative Diseases. Int J Mol Sci 2020; 21:ijms21165646. [PMID: 32781742 PMCID: PMC7460676 DOI: 10.3390/ijms21165646] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 08/01/2020] [Accepted: 08/04/2020] [Indexed: 02/07/2023] Open
Abstract
Neurodegenerative diseases are a major burden for our society, affecting millions of people worldwide. A main goal of past and current research is to enhance our understanding of the mechanisms underlying proteotoxicity, a common theme among these incurable and debilitating conditions. Cell proteome alteration is considered to be one of the main driving forces that triggers neurodegeneration, and unraveling the biological complexity behind the affected molecular pathways constitutes a daunting challenge. This review summarizes the current state on key processes that lead to cellular proteotoxicity in Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis, providing a comprehensive landscape of recent literature. A foundational understanding of how proteotoxicity affects disease etiology and progression may provide essential insight towards potential targets amenable of therapeutic intervention.
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81
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Evers MM, Konstantinova P. AAV5-miHTT gene therapy for Huntington disease: lowering both huntingtins. Expert Opin Biol Ther 2020; 20:1121-1124. [PMID: 32658606 DOI: 10.1080/14712598.2020.1792880] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Melvin M Evers
- Research, uniQure biopharma B.V , Amsterdam, The Netherlands
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82
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Schrank S, Barrington N, Stutzmann GE. Calcium-Handling Defects and Neurodegenerative Disease. Cold Spring Harb Perspect Biol 2020; 12:a035212. [PMID: 31427373 PMCID: PMC7328457 DOI: 10.1101/cshperspect.a035212] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Calcium signaling is critical to neuronal function and regulates highly diverse processes such as gene transcription, energy production, protein handling, and synaptic structure and function. Because there are many common underlying calcium-mediated pathological features observed across several neurological conditions, it has been proposed that neurodegenerative diseases have an upstream underlying calcium basis in their pathogenesis. With certain diseases such as Alzheimer's, Parkinson's, and Huntington's, specific sources of calcium dysregulation originating from distinct neuronal compartments or channels have been shown to have defined roles in initiating or sustaining disease mechanisms. Herein, we will review the major hallmarks of these diseases, and how they relate to calcium dysregulation. We will then discuss neuronal calcium handling throughout the neuron, with special emphasis on channels involved in neurodegeneration.
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Affiliation(s)
- Sean Schrank
- Center for Neurodegenerative Disease and Therapeutics, Rosalind Franklin University, North Chicago, Illinois 60064
- School of Graduate and Postdoctoral Studies, Rosalind Franklin University, North Chicago, Illinois 60064
| | - Nikki Barrington
- Center for Neurodegenerative Disease and Therapeutics, Rosalind Franklin University, North Chicago, Illinois 60064
- School of Graduate and Postdoctoral Studies, Rosalind Franklin University, North Chicago, Illinois 60064
- Chicago Medical School, Rosalind Franklin University, North Chicago, Illinois 60064
| | - Grace E Stutzmann
- Center for Neurodegenerative Disease and Therapeutics, Rosalind Franklin University, North Chicago, Illinois 60064
- School of Graduate and Postdoctoral Studies, Rosalind Franklin University, North Chicago, Illinois 60064
- Chicago Medical School, Rosalind Franklin University, North Chicago, Illinois 60064
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83
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Taran AS, Shuvalova LD, Lagarkova MA, Alieva IB. Huntington's Disease-An Outlook on the Interplay of the HTT Protein, Microtubules and Actin Cytoskeletal Components. Cells 2020; 9:E1514. [PMID: 32580314 PMCID: PMC7348758 DOI: 10.3390/cells9061514] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/17/2020] [Accepted: 06/17/2020] [Indexed: 12/13/2022] Open
Abstract
Huntington's disease is a severe and currently incurable neurodegenerative disease. An autosomal dominant mutation in the Huntingtin gene (HTT) causes an increase in the polyglutamine fragment length at the protein N-terminus. The consequence of the mutation is the death of neurons, mostly striatal neurons, leading to the occurrence of a complex of motor, cognitive and emotional-volitional personality sphere disorders in carriers. Despite intensive studies, the functions of both mutant and wild-type huntingtin remain poorly understood. Surprisingly, there is the selective effect of the mutant form of HTT even on nervous tissue, whereas the protein is expressed ubiquitously. Huntingtin plays a role in cell physiology and affects cell transport, endocytosis, protein degradation and other cellular and molecular processes. Our experimental data mining let us conclude that a significant part of the Huntingtin-involved cellular processes is mediated by microtubules and other cytoskeletal cell structures. The review attempts to look at unresolved issues in the study of the huntingtin and its mutant form, including their functions affecting microtubules and other components of the cell cytoskeleton.
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Affiliation(s)
- Aleksandra S. Taran
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 1–73, Leninsky Gory, 119992 Moscow, Russia; (A.S.T.); (L.D.S.)
| | - Lilia D. Shuvalova
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 1–73, Leninsky Gory, 119992 Moscow, Russia; (A.S.T.); (L.D.S.)
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 1a Malaya Pirogovskaya St., 119435 Moscow, Russia
| | - Maria A. Lagarkova
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 1a Malaya Pirogovskaya St., 119435 Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 1a Malaya Pirogovskaya St., 119435 Moscow, Russia
| | - Irina B. Alieva
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 1a Malaya Pirogovskaya St., 119435 Moscow, Russia
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1–40, Leninsky Gory, 119992 Moscow, Russia
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84
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Wild EJ, Tabrizi SJ. One decade ago, one decade ahead in huntington's disease. Mov Disord 2020; 34:1434-1439. [PMID: 31769087 DOI: 10.1002/mds.27849] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/13/2019] [Accepted: 08/18/2019] [Indexed: 12/15/2022] Open
Affiliation(s)
- Edward J Wild
- UCL Huntington's Disease Centre, Queen Square Institute of Neurology, London, UK
| | - Sarah J Tabrizi
- UCL Huntington's Disease Centre, Queen Square Institute of Neurology, London, UK
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85
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Tang BL. Could metformin be therapeutically useful in Huntington's disease? Rev Neurosci 2020; 31:297-317. [PMID: 31751298 DOI: 10.1515/revneuro-2019-0072] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 09/09/2019] [Indexed: 12/15/2022]
Abstract
Emerging evidence suggest that dimethylbiguanide (metformin), a first-line drug for type 2 diabetes mellitus, could be neuroprotective in a range of brain pathologies, which include neurodegenerative diseases and brain injury. However, there are also contraindications that associate metformin treatment with cognitive impairment as well as adverse outcomes in Alzheimer's disease and Parkinson's disease animal models. Recently, a beneficial effect of metformin in animal models of Huntington's disease (HD) has been strengthened by multiple reports. In this brief review, the findings associated with the effects of metformin in attenuating neurodegenerative diseases are discussed, focusing on HD-associated pathology and the potential underlying mechanisms highlighted by these studies. The mechanism of action of metformin is complex, and its therapeutic efficacy is therefore expected to be dependent on the disease context. The key metabolic pathways that are effectively affected by metformin, such as AMP-activated protein kinase activation, may be altered in the later decades of the human lifespan. In this regard, metformin may nonetheless be therapeutically useful for neurological diseases with early pathological onsets, such as HD.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University Health System, Singapore 117596, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Medical Drive, Singapore 119077, Singapore
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86
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Do Post-Translational Modifications Influence Protein Aggregation in Neurodegenerative Diseases: A Systematic Review. Brain Sci 2020; 10:brainsci10040232. [PMID: 32290481 PMCID: PMC7226274 DOI: 10.3390/brainsci10040232] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/05/2020] [Accepted: 04/07/2020] [Indexed: 12/14/2022] Open
Abstract
The accumulation of abnormal protein aggregates represents a universal hallmark of neurodegenerative diseases (NDDs). Post-translational modifications (PTMs) regulate protein structure and function. Dysregulated PTMs may influence the propensity for protein aggregation in NDD-proteinopathies. To investigate this, we systematically reviewed the literature to evaluate effects of PTMs on aggregation propensity for major proteins linked to the pathogenesis and/or progression of NDDs. A search of PubMed, MEDLINE, EMBASE, and Web of Science Core Collection was conducted to retrieve studies that investigated an association between PTMs and protein aggregation in seven NDDs: Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), spinocerebellar ataxias, transmissible spongiform encephalopathy, and multiple sclerosis. Together, 1222 studies were identified, of which 69 met eligibility criteria. We identified that the following PTMs, in isolation or combination, potentially act as modulators of proteinopathy in NDDs: isoaspartate formation in Aβ, phosphorylation of Aβ or tau in AD; acetylation, 4-hydroxy-2-neonal modification, O-GlcNAcylation or phosphorylation of α-synuclein in PD; acetylation or phosphorylation of TAR DNA-binding protein-43 in ALS, and SUMOylation of superoxide dismutase-1 in ALS; and phosphorylation of huntingtin in HD. The potential pharmacological manipulation of these aggregation-modulating PTMs represents an as-yet untapped source of therapy to treat NDDs.
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87
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Tereshchenko AV, Schultz JL, Bruss JE, Magnotta VA, Epping EA, Nopoulos PC. Abnormal development of cerebellar-striatal circuitry in Huntington disease. Neurology 2020; 94:e1908-e1915. [PMID: 32265233 DOI: 10.1212/wnl.0000000000009364] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 11/13/2019] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To test the hypothesis that the trajectory of functional connections over time of the striatum and the cerebellum differs between presymptomatic patients with the Huntington disease (HD) gene expansion (GE) and patients with a family history of HD but without the GE (GNE), we evaluated functional MRI data from the Kids-HD study. METHODS We utilized resting-state, functional MRI data from participants in the Kids-HD study between 6 and 18 years old. Participants were divided into GE (CAG 36-59) and GNE (CAG <36) groups. Seed-to-seed correlations were calculated among 4 regions that provide input signals to the anterior cerebellum: (1) dorsocaudal putamen, (2) globus pallidus externa, (3) subthalamic nucleus, and (4) pontine nuclei; and 2 regions that represented output from the cerebellum: the dentate nucleus to the (1) ventrolateral thalamus and (2) dorsocaudal putamen. Linear mixed effects regression models evaluated differences in developmental trajectories of these connections over time between groups. RESULTS Four of the six striatal-cerebellum correlations showed significantly different trajectories between groups. All showed a pattern where in the early age ranges (6-12 years) there was hyperconnectivity in the GE compared to the GNE, with those trajectories showing linear decline in the latter half of the age range. CONCLUSION These results parallel previous findings showing striatal hypertrophy in children with GE as early as age 6. These findings support the notion of developmentally higher connectivity between the striatum and cerebellum early in the life of the child with HD GE, possibly setting the stage for cerebellar compensatory mechanisms.
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88
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Egorova PA, Gavrilova AV, Bezprozvanny IB. Ataxic Symptoms in Huntington's Disease Transgenic Mouse Model Are Alleviated by Chlorzoxazone. Front Neurosci 2020; 14:279. [PMID: 32317916 PMCID: PMC7147686 DOI: 10.3389/fnins.2020.00279] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 03/11/2020] [Indexed: 12/11/2022] Open
Abstract
Huntington’s disease (HD) is a hereditary neurodegenerative disease caused by a polyglutamine expansion in the huntingtin protein, Striatum atrophy in HD leads to a progressive disturbance of psychiatric, motor, and cognitive function. Recent studies of HD patients revealed that the degeneration of cerebellum is also observed independently from the striatal atrophy during early HD stage and may contribute to the motor impairment and ataxia observed in HD. Cerebellar Purkinje cells (PCs) are responsible for the proper cerebellar pathways functioning and motor control. Recent studies on mouse models of HD have shown that the abnormality of the biochemical functions of PCs are observed in HD, suggesting the contribution of PC dysfunction and death to the impaired movement coordination observed in HD. To investigate ataxic symptoms in HD we performed a series of experiments with the yeast artificial chromosome transgenic mouse model of HD (YAC128). Using extracellular single-unit recording method we found that the portion of the cerebellar PCs with bursting and irregular patterns of spontaneous activity drastically rises in aged YAC128 HD mice when compared with wild type littermates. Previous studies demonstrated that SK channels are responsible for the cerebellar PC pacemaker activity and that positive modulation of SK channel activity exerted beneficial effects in different ataxic mouse models. Here we studied effects of the SK channels modulator chlorzoxazone (CHZ) on the motor behavior of YAC128 HD mice and also on the electrophysiological activity and neuroanatomy of the cerebellar PCs from these mice. We determined that the long-term intraperitoneal injections of CHZ alleviated the progressive impairment in the firing pattern of YAC128 PCs. We also demonstrated that treatment with CHZ rescued age-dependent motor incoordination and improved the cerebellar morphology in YAC128 mice. We propose that abnormal changes in the PC firing patterns might be a one of the possible causes of ataxic symptoms in HD and in other polyglutamine disorders and that the pharmacological activation of SK channels may serve as a potential way to improve the activity of cerebellar PCs and relieve the ataxic phenotype in HD patients.
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Affiliation(s)
- Polina A Egorova
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
| | - Aleksandra V Gavrilova
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
| | - Ilya B Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia.,Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, United States
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89
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Savage JC, St-Pierre MK, Carrier M, El Hajj H, Novak SW, Sanchez MG, Cicchetti F, Tremblay MÈ. Microglial physiological properties and interactions with synapses are altered at presymptomatic stages in a mouse model of Huntington's disease pathology. J Neuroinflammation 2020; 17:98. [PMID: 32241286 PMCID: PMC7118932 DOI: 10.1186/s12974-020-01782-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/20/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder that affects cognitive and motor abilities by primarily targeting the striatum and cerebral cortex. HD is caused by a mutation elongating the CAG repeats within the Huntingtin gene, resulting in HTT protein misfolding. Although the genetic cause of HD has been established, the specific susceptibility of neurons within various brain structures has remained elusive. Microglia, which are the brain's resident macrophages, have emerged as important players in neurodegeneration. Nevertheless, few studies have examined their implication in HD. METHODS To provide novel insights, we investigated the maturation and dysfunction of striatal microglia using the R6/2 mouse model of HD. This transgenic model, which presents with 120+/-5 CAG repeats, displays progressive motor deficits beginning at 6 weeks of age, with full incapacitation by 13 weeks. We studied microglial morphology, phagocytic capacity, and synaptic contacts in the striatum of R6/2 versus wild-type (WT) littermates at 3, 10, and 13 weeks of age, using a combination of light and transmission electron microscopy. We also reconstructed dendrites and determined synaptic density within the striatum of R6/2 and WT littermates, at nanoscale resolution using focused ion beam scanning electron microscopy. RESULTS At 3 weeks of age, prior to any known motor deficits, microglia in R6/2 animals displayed a more mature morphological phenotype than WT animals. Microglia from R6/2 mice across all ages also demonstrated increased phagocytosis, as revealed by light microscopy and transmission electron microscopy. Furthermore, microglial processes from 10-week-old R6/2 mice made fewer contacts with synaptic structures than microglial processes in 3-week-old R6/2 mice and age-matched WT littermates. Synaptic density was not affected by genotype at 3 weeks of age but increased with maturation in WT mice. The location of synapses was lastly modified in R6/2 mice compared with WT controls, from targeting dendritic spines to dendritic trunks at both 3 and 10 weeks of age. CONCLUSIONS These findings suggest that microglia may play an intimate role in synaptic alteration and loss during HD pathogenesis.
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Affiliation(s)
- Julie C Savage
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada.
| | - Marie-Kim St-Pierre
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
| | - Micaël Carrier
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
| | - Hassan El Hajj
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
| | - Sammy Weiser Novak
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
- Waitt Advanced Biophotonics Core, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Maria Gabriela Sanchez
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
| | - Francesca Cicchetti
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada
- Département de psychiatrie et neurosciences, Faculté de médecine, Université Laval, Québec, QC, Canada
| | - Marie-Ève Tremblay
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, T2-50, Québec, QC, G1V 4G2, Canada.
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Québec, QC, Canada.
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada.
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90
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Tousley A, Iuliano M, Weisman E, Sapp E, Zhang N, Vodicka P, Alexander J, Aviolat H, Gatune L, Reeves P, Li X, Khvorova A, Ellerby LM, Aronin N, DiFiglia M, Kegel-Gleason KB. Rac1 Activity Is Modulated by Huntingtin and Dysregulated in Models of Huntington's Disease. J Huntingtons Dis 2020; 8:53-69. [PMID: 30594931 PMCID: PMC6398565 DOI: 10.3233/jhd-180311] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Background: Previous studies suggest that Huntingtin, the protein mutated in Huntington’s disease (HD), is required for actin based changes in cell morphology, and undergoes stimulus induced targeting to plasma membranes where it interacts with phospholipids involved in cell signaling. The small GTPase Rac1 is a downstream target of growth factor stimulation and PI 3-kinase activity and is critical for actin dependent membrane remodeling. Objective: To determine if Rac1 activity is impaired in HD or regulated by normal Huntingtin. Methods: Analyses were performed in differentiated control and HD human stem cells and HD Q140/Q140 knock-in mice. Biochemical methods included SDS-PAGE, western blot, immunoprecipitation, affinity chromatography, and ELISA based Rac activity assays. Results: Basal Rac1 activity increased following depletion of Huntingtin with Huntingtin specific siRNA in human primary fibroblasts and in human control neuron cultures. Human cells (fibroblasts, neural stem cells, and neurons) with the HD mutation failed to increase Rac1 activity in response to growth factors. Rac1 activity levels were elevated in striatum of 1.5-month-old HD Q140/Q140 mice and in primary embryonic cortical neurons from HD mice. Affinity chromatography analysis of striatal lysates showed that Huntingtin is in a complex with Rac1, p85α subunit of PI 3-kinase, and the actin bundling protein α-actinin and interacts preferentially with the GTP bound form of Rac1. The HD mutation reduced Huntingtin interaction with p85α. Conclusions: These findings suggest that Huntingtin regulates Rac1 activity as part of a coordinated response to growth factor signaling and this function is impaired early in HD.
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Affiliation(s)
- Adelaide Tousley
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Maria Iuliano
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Elizabeth Weisman
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Ellen Sapp
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Ningzhe Zhang
- Buck Institute for Research on Aging, Novato, CA, USA
| | - Petr Vodicka
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Jonathan Alexander
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Hubert Aviolat
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Leah Gatune
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Patrick Reeves
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Xueyi Li
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Anastasia Khvorova
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA, USA
| | | | - Neil Aronin
- RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA, USA.,Department of Medicine and Cell Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Marian DiFiglia
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Kimberly B Kegel-Gleason
- Department of Neurology, Laboratory of Cellular Neurobiology, Massachusetts General Hospital, Charlestown, MA, USA
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91
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Gomboeva DE, Bragina EY, Nazarenko MS, Puzyrev VP. The Inverse Comorbidity between Oncological Diseases and Huntington’s Disease: Review of Epidemiological and Biological Evidence. RUSS J GENET+ 2020. [DOI: 10.1134/s1022795420030059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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92
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Loss of huntingtin function slows synaptic vesicle endocytosis in striatal neurons from the httQ140/Q140 mouse model of Huntington's disease. Neurobiol Dis 2020; 134:104637. [DOI: 10.1016/j.nbd.2019.104637] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 08/23/2019] [Accepted: 10/09/2019] [Indexed: 12/13/2022] Open
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93
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Fernández-Nogales M, Lucas JJ. Altered Levels and Isoforms of Tau and Nuclear Membrane Invaginations in Huntington's Disease. Front Cell Neurosci 2020; 13:574. [PMID: 32009905 PMCID: PMC6978886 DOI: 10.3389/fncel.2019.00574] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 12/12/2019] [Indexed: 12/13/2022] Open
Abstract
Since the early reports of neurofibrillary Tau pathology in brains of some Huntington’s disease (HD) patients, mounting evidence of multiple alterations of Tau in HD brain tissue has emerged in recent years. Such Tau alterations range from increased total levels, imbalance of isoforms generated by alternative splicing (increased 4R-/3R-Tau ratio) or by post-translational modifications such as hyperphosphorylation or truncation. Besides, the detection in HD brains of a new Tau histopathological hallmark known as Tau nuclear rods (TNRs) or Tau-positive nuclear indentations (TNIs) led to propose HD as a secondary Tauopathy. After their discovery in HD brains, TNIs have also been reported in hippocampal neurons of early Braak stage AD cases and in frontal and temporal cortical neurons of FTD-MAPT cases due to the intronic IVS10+16 mutation in the Tau gene (MAPT) which results in an increased 4R-/3R-Tau ratio similar to that observed in HD. TNIs are likely pathogenic for contributing to the disturbed nucleocytoplasmic transport observed in HD. A key question is whether correction of any of the mentioned Tau alterations might have positive therapeutic implications for HD. The beneficial effect of decreasing Tau expression in HD mouse models clearly implicates Tau in HD pathogenesis. Such beneficial effect might be exerted by diminishing the excess total levels of Tau or specifically by diminishing the excess 4R-Tau, as well as any of their downstream effects. In any case, since gene silencing drugs are under development to attenuate both Huntingtin (HTT) expression for HD and MAPT expression for FTD-MAPT, it is conceivable that the combined therapy in HD patients might be more effective than HTT silencing alone.
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Affiliation(s)
| | - José J Lucas
- Centro de Biología Molecular Severo Ochoa (CBMSO)(CSIC-UAM), Madrid, Spain.,Networking Research Center on Neurodegenerative Diseases (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
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94
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Zhao Q, Li C, Yu M, Sun Y, Wang J, Ma L, Sun X, Lu B. HuR stabilizes HTT mRNA via interacting with its exon 11 in a mutant HTT-dependent manner. RNA Biol 2020; 17:500-516. [PMID: 31928144 PMCID: PMC7237150 DOI: 10.1080/15476286.2020.1712894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Huntington’s Disease (HD) is a monogenetic neurodegenerative disorder mainly caused by the cytotoxicity of the mutant HTT protein (mHTT) encoded by the mutant HTT gene. Lowering HTT mRNA has been extensively studied as a potential therapeutic strategy, but how its level is regulated endogenously has been unclear. Here we report that the RNA-binding protein (RBP) HuR interacts with and stabilizes HTT mRNA in an mHTT-dependent manner. In HD cells but not wild-type cells, siRNA knockdown or CRISPR-induced heterozygous knockout of HuR decreased HTT mRNA stability. HuR interacted with HTT mRNA at a conserved site in exon 11 rather than the 3ʹ-UTR region of the mRNA. Interestingly, this interaction was dependent on the presence of mHTT, likely via the activation of MAPK11, which enhanced cytosolic localization of the HuR protein. Thus, mHTT, MAPK11 and HuR may form a positive feedback loop that stabilizes HTT mRNA and enhances mHTT accumulation, which may contribute to HD progression. Our data reveal a novel regulatory mechanism of HTT mRNA via non-canonical binding of HuR.
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Affiliation(s)
- Quan Zhao
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, School of Life Sciences, Fudan University, Shanghai, China
| | - Chen Li
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, School of Life Sciences, Fudan University, Shanghai, China
| | - Meng Yu
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, School of Life Sciences, Fudan University, Shanghai, China
| | - Yimin Sun
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, School of Life Sciences, Fudan University, Shanghai, China
| | - Jian Wang
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, School of Life Sciences, Fudan University, Shanghai, China
| | - Lixiang Ma
- Department of Anatomy, Histology and Embryology, Shanghai Basic Medical College, Fudan University, Shanghai, China
| | - Xiaoli Sun
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, School of Life Sciences, Fudan University, Shanghai, China.,Shanghai Xuhui District Central Hospital, Zhongshan Xuhui Hospital, Fudan University, Shanghai, China
| | - Boxun Lu
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Biomedical Sciences, School of Life Sciences, Fudan University, Shanghai, China
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95
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Bogomazova AN, Eremeev AV, Pozmogova GE, Lagarkova MA. The Role of Mutant RNA in the Pathogenesis of Huntington’s Disease and Other Polyglutamine Diseases. Mol Biol 2019. [DOI: 10.1134/s0026893319060037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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96
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Cepeda C, Oikonomou KD, Cummings D, Barry J, Yazon VW, Chen DT, Asai J, Williams CK, Vinters HV. Developmental origins of cortical hyperexcitability in Huntington's disease: Review and new observations. J Neurosci Res 2019; 97:1624-1635. [PMID: 31353533 PMCID: PMC6801077 DOI: 10.1002/jnr.24503] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 12/13/2022]
Abstract
Huntington's disease (HD), an inherited neurodegenerative disorder that principally affects striatum and cerebral cortex, is generally thought to have an adult onset. However, a small percentage of cases develop symptoms before 20 years of age. This juvenile variant suggests that brain development may be altered in HD. Indeed, recent evidence supports an important role of normal huntingtin during embryonic brain development and mutations in this protein cause cortical abnormalities. Functional studies also demonstrated that the cerebral cortex becomes hyperexcitable with disease progression. In this review, we examine clinical and experimental evidence that cortical development is altered in HD. We also provide preliminary evidence that cortical pyramidal neurons from R6/2 mice, a model of juvenile HD, are hyperexcitable and display dysmorphic processes as early as postnatal day 7. Further, some symptomatic mice present with anatomical abnormalities reminiscent of human focal cortical dysplasia, which could explain the occurrence of epileptic seizures in this genetic mouse model and in children with juvenile HD. Finally, we discuss recent treatments aimed at correcting abnormal brain development.
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Affiliation(s)
- Carlos Cepeda
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Katerina D. Oikonomou
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Damian Cummings
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Joshua Barry
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Vannah-Wila Yazon
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Dickson T. Chen
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Janelle Asai
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Christopher K. Williams
- Section of Neuropathology, Department of Pathology and Laboratory Medicine and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Harry V. Vinters
- Section of Neuropathology, Department of Pathology and Laboratory Medicine and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
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97
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Antibody-based therapies for Huntington’s disease: current status and future directions. Neurobiol Dis 2019; 132:104569. [DOI: 10.1016/j.nbd.2019.104569] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 08/01/2019] [Accepted: 08/02/2019] [Indexed: 12/12/2022] Open
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98
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Sidik H, Ang CJ, Pouladi MA. Huntingtin confers fitness but is not embryonically essential in zebrafish development. Dev Biol 2019; 458:98-105. [PMID: 31682806 DOI: 10.1016/j.ydbio.2019.10.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 10/17/2019] [Accepted: 10/31/2019] [Indexed: 11/25/2022]
Abstract
Attempts to constitutively knockout HTT in rodents resulted in embryonic lethality, curtailing efforts to study HTT function later in development. Here we show that HTT is dispensable for early zebrafish development, contrasting published zebrafish morpholino experiment results. Homozygous HTT knockouts were embryonically viable and appeared developmentally normal through juvenile stages. Comparison of adult fish revealed significant reduction in body size and fitness in knockouts compared to hemizygotes and wildtype fish, indicating an important role for wildtype HTT in postnatal development. Our zebrafish model provides an opportunity to understand the function of wildtype HTT later in development.
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Affiliation(s)
- Harwin Sidik
- Translational Laboratory in Genetic Medicine (TLGM), Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, Immunos, Level 5, 138648, Singapore
| | - Christy J Ang
- Translational Laboratory in Genetic Medicine (TLGM), Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, Immunos, Level 5, 138648, Singapore
| | - Mahmoud A Pouladi
- Translational Laboratory in Genetic Medicine (TLGM), Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, Immunos, Level 5, 138648, Singapore; Department of Medicine, National University of Singapore, 117597, Singapore; Department of Physiology, National University of Singapore, 117597, Singapore.
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99
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Lee D, Liu J, Junn HJ, Lee EJ, Jeong KS, Seol DW. No more helper adenovirus: production of gutless adenovirus (GLAd) free of adenovirus and replication-competent adenovirus (RCA) contaminants. Exp Mol Med 2019; 51:1-18. [PMID: 31659156 PMCID: PMC6817846 DOI: 10.1038/s12276-019-0334-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 09/13/2019] [Accepted: 09/18/2019] [Indexed: 12/13/2022] Open
Abstract
Gene therapy is emerging as an effective treatment option for various inherited genetic diseases. Gutless adenovirus (GLAd), also known as helper-dependent adenovirus (HDAd), has many notable characteristics as a gene delivery vector for this particular type of gene therapy, including broad tropism, high infectivity, a large transgene cargo capacity, and an absence of integration into the host genome. Additionally, GLAd ensures long-term transgene expression in host organisms owing to its minimal immunogenicity, since it was constructed following the deletion of all the genes from an adenovirus. However, the clinical use of GLAd for the treatment of inherited genetic diseases has been hampered by unavoidable contamination of the highly immunogenic adenovirus used as a helper for GLAd production. Here, we report the production of GLAd in the absence of a helper adenovirus, which was achieved with a helper plasmid instead. Utilizing this helper plasmid, we successfully produced large quantities of recombinant GLAd. Importantly, our helper plasmid-based system exclusively produced recombinant GLAd with no generation of helper plasmid-originating adenovirus and replication-competent adenovirus (RCA). The recombinant GLAd that was produced efficiently delivered transgenes regardless of their size and exhibited therapeutic potential for Huntington’s disease (HD) and Duchenne muscular dystrophy (DMD). Our data indicate that our helper plasmid-based GLAd production system could become a new platform for GLAd-based gene therapy. A new protocol allows for the manufacturing of a next-generation gene therapy vector without contamination of helper adenovirus and replication-competent adenovirus (RCA). Adenoviruses are often used to deliver therapeutic DNA, but their proteins can trigger immune reactions. So-called ‘gutless’ adenoviruses that lack all viral genes don’t cause the same problem but their production has traditionally relied on a helper adenovirus that remains as an unavoidable contaminant. A team led by Dai-Wu Seol from Chung-Ang University in Seoul, South Korea, has now prepared large quantities of gutless adenoviruses using helper plasmid, a circular DNA that encodes all the proteins needed for production of gutless adenoviruses but do not leave behind any contaminant adenoviruses. Gutless adenoviruse vectors made this way successfully delivered corrected copies of the faulty genes responsible for human diseseas into human cells and mice.
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Affiliation(s)
- Dongwoo Lee
- Genenmed Inc., 84 Seongsuil-ro, Seongdong-gu, Seoul, Republic of Korea
| | - Jida Liu
- College of Pharmacy, Chung-Ang University, Seoul, Republic of Korea
| | - Hyun Jung Junn
- Genenmed Inc., 84 Seongsuil-ro, Seongdong-gu, Seoul, Republic of Korea
| | - Eun-Joo Lee
- Department of Veterinary Pathology, College of Veterinary Medicine, Kyungpook National University, Daegu City, Republic of Korea
| | - Kyu-Shik Jeong
- Department of Veterinary Pathology, College of Veterinary Medicine, Kyungpook National University, Daegu City, Republic of Korea
| | - Dai-Wu Seol
- College of Pharmacy, Chung-Ang University, Seoul, Republic of Korea.
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100
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CRISPR-Cas9-Mediated Genome Editing Increases Lifespan and Improves Motor Deficits in a Huntington's Disease Mouse Model. MOLECULAR THERAPY-NUCLEIC ACIDS 2019; 17:829-839. [PMID: 31465962 PMCID: PMC6717077 DOI: 10.1016/j.omtn.2019.07.009] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/29/2019] [Accepted: 07/16/2019] [Indexed: 12/11/2022]
Abstract
Huntington’s disease (HD) is a currently incurable and, ultimately, fatal neurodegenerative disorder caused by a CAG trinucleotide repeat expansion within exon 1 of the huntingtin (HTT) gene, which results in the production of a mutant protein that forms inclusions and selectively destroys neurons in the striatum and other adjacent structures. The RNA-guided Cas9 endonuclease from CRISPR-Cas9 systems is a versatile technology for inducing DNA double-strand breaks that can stimulate the introduction of frameshift-inducing mutations and permanently disable mutant gene function. Here, we show that the Cas9 nuclease from Staphylococcus aureus, a small Cas9 ortholog that can be packaged alongside a single guide RNA into a single adeno-associated virus (AAV) vector, can be used to disrupt the expression of the mutant HTT gene in the R6/2 mouse model of HD following its in vivo delivery to the striatum. Specifically, we found that CRISPR-Cas9-mediated disruption of the mutant HTT gene resulted in a ∼50% decrease in neuronal inclusions and significantly improved lifespan and certain motor deficits. These results thus illustrate the potential for CRISPR-Cas9 technology to treat HD and other autosomal dominant neurodegenerative disorders caused by a trinucleotide repeat expansion via in vivo genome editing.
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