Analysis of mutant and total huntingtin expression in Huntington’s disease murine models

AbstractHuntington’s disease (HD) is a monogenetic neurodegenerative disorder that is caused by the expansion of a polyglutamine region within the huntingtin (HTT) protein, but there is still an incomplete understanding of the molecular mechanisms that drive pathology. Expression of the mutant form of HTT is a key aspect of diseased tissues, and the most promising therapeutic approaches aim to lower expanded HTT levels. Consequently, the investigation of HTT expression in time and in multiple tissues, with assays that accurately quantify expanded and non-expanded HTT, are required to delineate HTT homeostasis and to best design and interpret pharmacodynamic readouts for HTT lowering therapeutics. Here we evaluate mutant polyglutamine-expanded (mHTT) and polyglutamine-independent HTT specific immunoassays for validation in human HD and control fibroblasts and use to elucidate the CSF/brain and peripheral tissue expression of HTT in preclinical HD models.

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Non-Cell Autonomous and Epigenetic Mechanisms of Huntington’s Disease

International Journal of Molecular Sciences ◽

10.3390/ijms222212499 ◽

2021 ◽

Vol 22 (22) ◽

pp. 12499

Author(s):

Chaebin Kim ◽

Ali Yousefian-Jazi ◽

Seung-Hye Choi ◽

Inyoung Chang ◽

Junghee Lee ◽

...

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Trinucleotide Repeat ◽

Neurodegenerative Disorder ◽

Involuntary Movement ◽

Therapeutic Approaches ◽

Exon 1 ◽

Human Chromosome 4 ◽

The Brain

Huntington’s disease (HD) is a rare neurodegenerative disorder caused by an expansion of CAG trinucleotide repeat located in the exon 1 of Huntingtin (HTT) gene in human chromosome 4. The HTT protein is ubiquitously expressed in the brain. Specifically, mutant HTT (mHTT) protein-mediated toxicity leads to a dramatic degeneration of the striatum among many regions of the brain. HD symptoms exhibit a major involuntary movement followed by cognitive and psychiatric dysfunctions. In this review, we address the conventional role of wild type HTT (wtHTT) and how mHTT protein disrupts the function of medium spiny neurons (MSNs). We also discuss how mHTT modulates epigenetic modifications and transcriptional pathways in MSNs. In addition, we define how non-cell autonomous pathways lead to damage and death of MSNs under HD pathological conditions. Lastly, we overview therapeutic approaches for HD. Together, understanding of precise neuropathological mechanisms of HD may improve therapeutic approaches to treat the onset and progression of HD.

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Wild-type huntingtin regulates human macrophage function

Scientific Reports ◽

10.1038/s41598-020-74042-8 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Grace C. O’Regan ◽

Sahar H. Farag ◽

Gary R. Ostroff ◽

Sarah J. Tabrizi ◽

Ralph Andre

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Neurodegenerative Disorder ◽

Human Subjects ◽

Central Nervous System Disease ◽

Human Macrophage ◽

Mutant Form ◽

Wild Type ◽

Macrophage Function ◽

System Disease

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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Molecular Mechanisms and Potential Therapeutical Targets in Huntington's Disease

Physiological Reviews ◽

10.1152/physrev.00041.2009 ◽

2010 ◽

Vol 90 (3) ◽

pp. 905-981 ◽

Cited By ~ 524

Author(s):

Chiara Zuccato ◽

Marta Valenza ◽

Elena Cattaneo

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Molecular Mechanisms ◽

Neurodegenerative Disorder ◽

Disease Process ◽

Primary Source ◽

Cag Repeat ◽

Mutant Protein ◽

Loss Of Function ◽

Causative Gene

Huntington's disease (HD) is a neurodegenerative disorder caused by a CAG repeat expansion in the gene encoding for huntingtin protein. A lot has been learned about this disease since its first description in 1872 and the identification of its causative gene and mutation in 1993. We now know that the disease is characterized by several molecular and cellular abnormalities whose precise timing and relative roles in pathogenesis have yet to be understood. HD is triggered by the mutant protein, and both gain-of-function (of the mutant protein) and loss-of-function (of the normal protein) mechanisms are involved. Here we review the data that describe the emergence of the ancient huntingtin gene and of the polyglutamine trait during the last 800 million years of evolution. We focus on the known functions of wild-type huntingtin that are fundamental for the survival and functioning of the brain neurons that predominantly degenerate in HD. We summarize data indicating how the loss of these beneficial activities reduces the ability of these neurons to survive. We also review the different mechanisms by which the mutation in huntingtin causes toxicity. This may arise both from cell-autonomous processes and dysfunction of neuronal circuitries. We then focus on novel therapeutical targets and pathways and on the attractive option to counteract HD at its primary source, i.e., by blocking the production of the mutant protein. Strategies and technologies used to screen for candidate HD biomarkers and their potential application are presented. Furthermore, we discuss the opportunities offered by intracerebral cell transplantation and the likely need for these multiple routes into therapies to converge at some point as, ideally, one would wish to stop the disease process and, at the same time, possibly replace the damaged neurons.

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Temporal Control Deficits in Murine Models of Huntington’s Disease

International Journal of Comparative Psychology ◽

10.46867/ijcp.2015.28.02.05 ◽

2015 ◽

Vol 28 ◽

Author(s):

Dani Brunner ◽

Fuat Balcı ◽

Paul C.P Curtin ◽

Andrew Farrar ◽

Steve Oakeshott ◽

...

Keyword(s):

Information Processing ◽

Huntington's Disease ◽

Huntington’S Disease ◽

Neurodegenerative Disorder ◽

Temporal Information ◽

Temporal Control ◽

Response Curves ◽

Temporal Information Processing ◽

Trial Analysis ◽

And Control

Timing is a ubiquitous process that underlies a great variety of human activities and depends on highly conserved neuronal circuitry, the cortico-striatal loops. The peak interval (PI) task is an operant task that conditions subjects to initiate and terminate behavioral responses bracketing a fixed interval associated with reinforcement. Performance in this task depends on the efficacy of temporal control processes that coordinate interval encoding and decoding, instrumental response innitiation, cessation and maintenance, and motor control. Here, we used the PI procedure to characterize temporal control in zQ175 knockin (KI) and BAC HD transgenic (Tg) mice generated to model Huntington's Disease (HD), and contrast the result with previously published R6/2 Tg PI data. HD is a progressive neurodegenerative disorder that involves degeneration of the same neural circuits underlying temporal information processing and control of motor output. Our results indicate that temporal control is disrupted in R6/2 Tg and zQ175 KI mice but intact in BAC HD Tg mice. Trial-by-trial analysis of break-run patterns in response rates indicated that shifts in zQ175 KI response curves were driven by significant delays in response initiation and cessation. Similar temporal control deficits were previously reported in HD patients and R6/2 transgenic HD mice. These findings support the use of zQ175 mice in preclinical studies of HD-related cognitive deficits. They provide evidence of a strong homology between the human and rodent neural bases of temporal information processing, temporal response control, and their pathology in neurodegeneration.

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Molecular Mechanisms Underlying Muscle Wasting in Huntington’s Disease

International Journal of Molecular Sciences ◽

10.3390/ijms21218314 ◽

2020 ◽

Vol 21 (21) ◽

pp. 8314

Author(s):

Manuela Bozzi ◽

Francesca Sciandra

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Muscle Atrophy ◽

Protein Misfolding ◽

Energy Homeostasis ◽

Molecular Mechanisms ◽

Protein Quality ◽

Neurodegenerative Disorder ◽

Wide Spectrum ◽

Muscular Tissue

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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Hippocampal Neurogenesis, Cognitive Deficits and Affective Disorder in Huntington's Disease

Neural Plasticity ◽

10.1155/2012/874387 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 28

Author(s):

Mark I. Ransome ◽

Thibault Renoir ◽

Anthony J. Hannan

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Mouse Models ◽

Adult Neurogenesis ◽

Molecular Mechanisms ◽

Neurodegenerative Disorder ◽

Brain Regions ◽

Transgenic Animal ◽

Hippocampal Neurogenesis ◽

Adult Hippocampal Neurogenesis

Huntington’s disease (HD) is a neurodegenerative disorder caused by a tandem repeat expansion encoding a polyglutamine tract in the huntingtin protein. HD involves progressive psychiatric, cognitive, and motor symptoms, the selective pathogenesis of which remains to be mechanistically elucidated. There are a range of different brain regions, including the cerebral cortex and striatum, known to be affected in HD, with evidence for hippocampal dysfunction accumulating in recent years. In this review we will focus on hippocampal abnormalities, in particular, deficits of adult neurogenesis. We will discuss potential molecular mechanisms mediating disrupted hippocampal neurogenesis, and how this deficit of cellular plasticity may in turn contribute to specific cognitive and affective symptoms that are prominent in HD. The generation of transgenic animal models of HD has greatly facilitated our understanding of disease mechanisms at molecular, cellular, and systems levels. Transgenic HD mice have been found to show progressive behavioral changes, including affective, cognitive, and motor abnormalities. The discovery, in multiple transgenic lines of HD mice, that adult hippocampal neurogenesis and synaptic plasticity is disrupted, may help explain specific aspects of cognitive and affective dysfunction. Furthermore, these mouse models have provided insight into potential molecular mediators of adult neurogenesis deficits, such as disrupted serotonergic and neurotrophin signaling. Finally, a number of environmental and pharmacological interventions which are known to enhance adult hippocampal neurogenesis have been found to have beneficial affective and cognitive effects in mouse models, suggesting common molecular targets which may have therapeutic utility for HD and related diseases.

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

Pharmaceuticals ◽

10.3390/ph14030257 ◽

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.

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

Frontiers in Neurology ◽

10.3389/fneur.2020.573560 ◽

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.

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Huntington's Disease: An Immune Perspective

Neurology Research International ◽

10.1155/2011/563784 ◽

2011 ◽

Vol 2011 ◽

pp. 1-7 ◽

Cited By ~ 12

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.

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

Pharmaceuticals ◽

10.3390/ph14101044 ◽

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.

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