scholarly journals Huntington’s Disease Pathogenesis: Two Sequential Components

2021 ◽  
Vol 10 (1) ◽  
pp. 35-51 ◽  
Author(s):  
Eun Pyo Hong ◽  
Marcy E. MacDonald ◽  
Vanessa C. Wheeler ◽  
Lesley Jones ◽  
Peter Holmans ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Human Genetics ◽  
Neurodegenerative Disorder ◽  
Genetic Defect ◽  
Genome Project ◽  
Dna Polymorphisms ◽  
Genetic Linkage Analysis ◽  
Abnormal Movements ◽  
Hd Gene

Historically, Huntington’s disease (HD; OMIM #143100) has played an important role in the enormous advances in human genetics seen over the past four decades. This familial neurodegenerative disorder involves variable onset followed by consistent worsening of characteristic abnormal movements along with cognitive decline and psychiatric disturbances. HD was the first autosomal disease for which the genetic defect was assigned to a position on the human chromosomes using only genetic linkage analysis with common DNA polymorphisms. This discovery set off a multitude of similar studies in other diseases, while the HD gene, later renamed HTT, and its vicinity in chromosome 4p16.3 then acted as a proving ground for development of technologies to clone and sequence genes based upon their genomic location, with the growing momentum of such advances fueling the Human Genome Project. The identification of the HD gene has not yet led to an effective treatment, but continued human genetic analysis of genotype-phenotype relationships in large HD subject populations, first at the HTT locus and subsequently genome-wide, has provided insights into pathogenesis that divide the course of the disease into two sequential, mechanistically distinct components.

Huntington's disease: molecular basis of neurodegeneration

2003 ◽  
Vol 5 (20) ◽  
pp. 1-21 ◽  
Author(s):  
David C. Rubinsztein ◽  
Jenny Carmichael
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Trinucleotide Repeat ◽  
Neurodegenerative Disorder ◽  
Current Status ◽  
Soluble Form ◽  
Polyglutamine Expansion ◽  
Wide Range ◽  
Polyglutamine Tract ◽  
Hd Gene

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the HD gene. The expanded repeats are translated into an abnormally long polyglutamine tract close to the N-terminus of the HD gene product (‘huntingtin’). Studies in humans and mouse models suggest that the mutation is associated with a deleterious gain-of-function. Several studies have suggested that the large huntingtin protein is cleaved to produce a shorter N-terminal fragment containing the polyglutamine expansion, and that the polyglutamine expansion causes the protein fragment to misfold and form aggregates (inclusions) in the nuclei and processes of neurons. It is likely that neurotoxicity is caused by the misfolded protein in its soluble form, and/or in aggregates, and/or in the process of aggregation. A wide range of potential mechanisms for neurotoxicity have been proposed, including caspase activation, dysregulation of transcriptional pathways, increased production of reactive oxygen species, and inhibition of proteasome activity. In this review we consider the current status of research in the field and possible mechanisms whereby the HD mutation might result in neurodegeneration.

Correlations between molecular and clinical data in Huntington's disease and implications for predictive testing

1995 ◽  
Vol 7 (1) ◽  
pp. 7-12
Author(s):  
S. Claes ◽  
M. Decruyenaere ◽  
R. Dom ◽  
M. Malfroid ◽  
G. Evers-Kiebooms ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Clinical Data ◽  
Human Genetics ◽  
Age At Onset ◽  
Genetic Defect ◽  
Biological Marker ◽  
Predictive Testing ◽  
Testing Procedure ◽  
Autosomal Dominant Disorder

SummaryHuntington's disease (HD) is an autosomal dominant disorder of the central nervous system, characterised by neurological, cognitive and psychiatric pathology. Recently the causative genetic defect was discovered. We present a retrospective study of 59 HD patients, investigating correlations between molecular and clinical data.The correlation between CAG-repeatlength and age at onset is confirmed. No correlations between this biological marker and other clinical features are found (symptoms at onset, mode of progression of the disease).The consequences of these findings for predictive testing are discussed. Furthermore, a short overview of the predictive testing procedure in the Center for Human Genetics in Leuven (Belgium) is given.

scholarly journals Epigenomic Remodeling in Huntington’s Disease—Master or Servant?

Epigenomes ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 15
Author(s):  
Geraldine Zimmer-Bensch
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Genetic Defect ◽  
Neuronal Loss ◽  
Histone Variants ◽  
Therapeutic Concepts ◽  
Exon 1 ◽  
Epigenetic Signatures ◽  
Neuronal Physiology

In light of our aging population, neurodegenerative disorders are becoming a tremendous challenge, that modern societies have to face. They represent incurable, progressive conditions with diverse and complex pathological features, followed by catastrophic occurrences of massive neuronal loss at the later stages of the diseases. Some of these disorders, like Huntington’s disease (HD), rely on defined genetic factors. HD, as an incurable, fatal hereditary neurodegenerative disorder characterized by its mid-life onset, is caused by the expansion of CAG trinucleotide repeats coding for glutamine (Q) in exon 1 of the huntingtin gene. Apart from the genetic defect, environmental factors are thought to influence the risk, onset and progression of HD. As epigenetic mechanisms are known to readily respond to environmental stimuli, they are proposed to play a key role in HD pathogenesis. Indeed, dynamic epigenomic remodeling is observed in HD patients and in brains of HD animal models. Epigenetic signatures, such as DNA methylation, histone variants and modifications, are known to influence gene expression and to orchestrate various aspects of neuronal physiology. Hence, deciphering their implication in HD pathogenesis might open up new paths for novel therapeutic concepts, which are discussed in this review.

scholarly journals Hypomorphic mutation of the mouse Huntington’s disease gene orthologue

2018 ◽  
Author(s):  
Vidya Murthy ◽  
Toma Tebaldi ◽  
Toshimi Yoshida ◽  
Serkan Erdin ◽  
Teresa Calzonetti ◽  
...  
Keyword(s):  
Body Size ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Gene Product ◽  
Molecular Analysis ◽  
Neurodegenerative Disorder ◽  
Therapeutic Strategies ◽  
Cag Repeat ◽  
Organ Development ◽  
Hd Gene

AbstractRare individuals with hypomorphic inactivating mutations in the Huntington’s Disease (HD) gene (HTT), identified by CAG repeat expansion in the eponymous neurodegenerative disorder, exhibit variable abnormalities that implyHTTessential roles during organ development. Here we report phenotypes produced when increasingly severe hypomorphic mutations inHtt, the murineHTTorthologue (inHdhneoQ20,HdhneoQ50,HdhneoQ111mice), were placed over a null allele (Hdhex4/5). The most severe hypomorphic allele failed to rescue null lethality at gastrulation, while the intermediate alleles yielded perinatal lethality and a variety of fetal abnormalities affecting body size, skin, skeletal and ear formation, and transient defects in hematopoiesis. Comparative molecular analysis of wild-type andHtt-null retinoic acid-differentiated cells revealed gene network dysregulation associated with organ development and proposed polycomb repressive complexes and miRNAs as molecular mediators. Together these findings demonstrate that the HD gene acts both pre- and post-gastrulation and possibly suggest pleiotropic consequences ofHTT-lowering therapeutic strategies.Author SummaryTheHTTgene product mutated in Huntington’s Disease (HD) has essential roles during normal organism development, however, still not fully predictable are the functional consequences of its partial inactivation. Our genetic study provides a comprehensive effects’ description of progressively stronger suppression ofHttgene, the murineHTTcounterpart. The most severeHttreduction leads to embryo lethality, while intermediateHttdosages yield a variety of developmental abnormalities affecting body size, skin, skeletal and ear formation, and hematopoiesis. Complementing molecular analysis in differentiating cells depleted of a functionalHttgene further elucidates genes’ networks dysregulated during organ development and proposes chromatin regulators and short non-coding RNAs as key molecular mediators. Together these findings demonstrate that the HD gene acts both at early and later stages of development, thus possibly suggesting long-term consequences associated to the newest HD therapeutic strategies aimed at lowering theHTTgene product.

scholarly journals The Contribution of Somatic Expansion of the CAG Repeat to Symptomatic Development in Huntington’s Disease: A Historical Perspective

2021 ◽  
Vol 10 (1) ◽  
pp. 7-33
Author(s):  
Darren G. Monckton
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Human Genetics ◽  
Age At Onset ◽  
Cag Repeat ◽  
Model Systems ◽  
Causative Mutation ◽  
Inverse Association ◽  
Independent Manner ◽  
Dna Mismatch

The discovery in the early 1990s of the expansion of unstable simple sequence repeats as the causative mutation for a number of inherited human disorders, including Huntington’s disease (HD), opened up a new era of human genetics and provided explanations for some old problems. In particular, an inverse association between the number of repeats inherited and age at onset, and unprecedented levels of germline instability, biased toward further expansion, provided an explanation for the wide symptomatic variability and anticipation observed in HD and many of these disorders. The repeats were also revealed to be somatically unstable in a process that is expansion-biased, age-dependent and tissue-specific, features that are now increasingly recognised as contributory to the age-dependence, progressive nature and tissue specificity of the symptoms of HD, and at least some related disorders. With much of the data deriving from affected individuals, and model systems, somatic expansions have been revealed to arise in a cell division-independent manner in critical target tissues via a mechanism involving key components of the DNA mismatch repair pathway. These insights have opened new approaches to thinking about how the disease could be treated by suppressing somatic expansion and revealed novel protein targets for intervention. Exciting times lie ahead in turning these insights into novel therapies for HD and related disorders.

scholarly journals The Novel Alpha-2 Adrenoceptor Inhibitor Beditin Reduces Cytotoxicity and Huntingtin Aggregates in Cell Models of Huntington’s Disease

2021 ◽  
Vol 14 (3) ◽  
pp. 257
Author(s):  
Elisabeth Singer ◽  
Lilit Hunanyan ◽  
Magda M. Melkonyan ◽  
Jonasz J. Weber ◽  
Lusine Danielyan ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Cell Model ◽  
Resonance Energy Transfer ◽  
Neuronal Cell ◽  
Resonance Energy ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Tunel Staining ◽  
Cell Models

Huntington’s disease (HD) is a monogenetic neurodegenerative disorder characterized by the accumulation of polyglutamine-expanded huntingtin (mHTT). There is currently no cure, and therefore disease-slowing remedies are sought to alleviate symptoms of the multifaceted disorder. Encouraging findings in Alzheimer’s and Parkinson’s disease on alpha-2 adrenoceptor (α2-AR) inhibition have shown neuroprotective and aggregation-reducing effects in cell and animal models. Here, we analyzed the effect of beditin, a novel α2- adrenoceptor (AR) antagonist, on cell viability and mHTT protein levels in cell models of HD using Western blot, time-resolved Foerster resonance energy transfer (TR-FRET), lactate dehydrogenase (LDH) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) cytotoxicity assays. Beditin decreases cytotoxicity, as measured by TUNEL staining and LDH release, in a neuronal progenitor cell model (STHdh cells) of HD and decreases the aggregation propensity of HTT exon 1 fragments in an overexpression model using human embryonic kidney (HEK) 293T cells. α2-AR is a promising therapeutic target for further characterization in HD models. Our data allow us to suggest beditin as a valuable candidate for the pharmaceutical manipulation of α2-AR, as it is capable of modulating neuronal cell survival and the level of mHTT.

scholarly journals RNA Sequencing of Human Peripheral Blood Cells Indicates Upregulation of Immune-Related Genes in Huntington's Disease

2020 ◽  
Vol 11 ◽  
Author(s):  
Miguel A. Andrade-Navarro ◽  
Katja Mühlenberg ◽  
Eike J. Spruth ◽  
Nancy Mah ◽  
Adrián González-López ◽  
...  
Keyword(s):  
Gene Expression ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Trinucleotide Repeat ◽  
Neurodegenerative Disorder ◽  
Gene Expression Signature ◽  
Interferon Response ◽  
Peripheral Blood Cells

Huntington's disease (HD) is an autosomal dominantly inherited neurodegenerative disorder caused by a trinucleotide repeat expansion in the Huntingtin gene. As disease-modifying therapies for HD are being developed, peripheral blood cells may be used to indicate disease progression and to monitor treatment response. In order to investigate whether gene expression changes can be found in the blood of individuals with HD that distinguish them from healthy controls, we performed transcriptome analysis by next-generation sequencing (RNA-seq). We detected a gene expression signature consistent with dysregulation of immune-related functions and inflammatory response in peripheral blood from HD cases vs. controls, including induction of the interferon response genes, IFITM3, IFI6 and IRF7. Our results suggest that it is possible to detect gene expression changes in blood samples from individuals with HD, which may reflect the immune pathology associated with the disease.

scholarly journals Huntington's Disease: An Immune Perspective

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Annapurna Nayak ◽  
Rafia Ansar ◽  
Sunil K. Verma ◽  
Domenico Marco Bonifati ◽  
Uday Kishore
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Typical Feature ◽  
Trinucleotide Repeats ◽  
Mutant Huntingtin Protein ◽  
Unexplored Area ◽  
Cag Trinucleotide Repeats ◽  
The Brain ◽  
Abnormal Expansion

Huntington's disease (HD) is a progressive neurodegenerative disorder that is caused by abnormal expansion of CAG trinucleotide repeats. Neuroinflammation is a typical feature of most neurodegenerative diseases that leads to an array of pathological changes within the affected areas in the brain. The neurodegeneration in HD is also caused by aberrant immune response in the presence of aggregated mutant huntingtin protein. The effects of immune activation in HD nervous system are a relatively unexplored area of research. This paper summarises immunological features associated with development and progression of HD.

scholarly journals Esculetin Provides Neuroprotection against Mutant Huntingtin-Induced Toxicity in Huntington’s Disease Models

2021 ◽  
Vol 14 (10) ◽  
pp. 1044
Author(s):  
Letizia Pruccoli ◽  
Carlo Breda ◽  
Gabriella Teti ◽  
Mirella Falconi ◽  
Flaviano Giorgini ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neuronal Death ◽  
Trinucleotide Repeat ◽  
Neurodegenerative Disorder ◽  
Positive Impact ◽  
Neuroprotective Effects ◽  
Drosophila Model ◽  
Exon 1 ◽  
Transgenic Drosophila

Huntington’s disease (HD) is a neurodegenerative disorder caused by an abnormal CAG trinucleotide repeat expansion within exon 1 of the huntingtin (HTT) gene. This mutation leads to the production of mutant HTT (mHTT) protein which triggers neuronal death through several mechanisms. Here, we investigated the neuroprotective effects of esculetin (ESC), a bioactive phenolic compound, in an inducible PC12 model and a transgenic Drosophila melanogaster model of HD, both of which express mHTT fragments. ESC partially inhibited the progression of mHTT aggregation and reduced neuronal death through its ability to counteract the oxidative stress and mitochondria impairment elicited by mHTT in the PC12 model. The ability of ESC to counteract neuronal death was also confirmed in the transgenic Drosophila model. Although ESC did not modify the lifespan of the transgenic Drosophila, it still seemed to have a positive impact on the HD phenotype of this model. Based on our findings, ESC may be further studied as a potential neuroprotective agent in a rodent transgenic model of HD.

scholarly journals Insights into kinetics, release, and behavioral effects of brain-targeted hybrid nanoparticles for cholesterol delivery in Huntington’s disease

2020 ◽  
Author(s):  
Giulia Birolini ◽  
Marta Valenza ◽  
Ilaria Ottonelli ◽  
Alice Passoni ◽  
Monica Favagrossa ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Neurodegenerative Disorder ◽  
Polymeric Nanoparticles ◽  
Cholesterol Biosynthesis ◽  
Hybrid Nanoparticles ◽  
Neural Cells ◽  
Peripheral Tissues ◽  
Brain Cholesterol ◽  
The Brain

AbstractSupplementing brain cholesterol is emerging as a potential treatment for Huntington’s disease (HD), a genetic neurodegenerative disorder characterized, among other abnormalities, by inefficient brain cholesterol biosynthesis. However, delivering cholesterol to the brain is challenging due to the bloodbrain barrier (BBB), which prevents it from reaching the striatum, especially, with therapeutically relevant doses.Here we describe the distribution, kinetics, release, and safety of novel hybrid polymeric nanoparticles made of PLGA and cholesterol which were modified with an heptapeptide (g7) for BBB transit (hybrid-g7-NPs-chol). We show that these NPs rapidly reach the brain and target neural cells. Moreover, deuterium-labeled cholesterol from hybrid-g7-NPs-chol is released in a controlled manner within the brain and accumulates over time, while being rapidly removed from peripheral tissues and plasma. We confirm that systemic and repeated injections of the new hybrid-g7-NPs-chol enhanced endogenous cholesterol biosynthesis, prevented cognitive decline, and ameliorated motor defects in HD animals, without any inflammatory reaction.In summary, this study provides insights about the benefits and safety of cholesterol delivery through advanced brain-permeable nanoparticles for HD treatment.

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