Wild-type huntingtin regulates human macrophage function

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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Huntington’s Disease—An Outlook on the Interplay of the HTT Protein, Microtubules and Actin Cytoskeletal Components

Cells ◽

10.3390/cells9061514 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1514 ◽

Cited By ~ 2

Author(s):

Aleksandra S. Taran ◽

Lilia D. Shuvalova ◽

Maria A. Lagarkova ◽

Irina B. Alieva

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Autosomal Dominant ◽

Cell Physiology ◽

Mutant Form ◽

Striatal Neurons ◽

Molecular Processes ◽

Wild Type ◽

Cellular Processes ◽

Cell Structures

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

Scientific Reports ◽

10.1038/s41598-020-78790-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Valentina Fodale ◽

Roberta Pintauro ◽

Manuel Daldin ◽

Roberta Altobelli ◽

Maria Carolina Spiezia ◽

...

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Molecular Mechanisms ◽

Neurodegenerative Disorder ◽

Tissue Expression ◽

Peripheral Tissue ◽

Mutant Form ◽

Murine Models ◽

Therapeutic Approaches ◽

And Control

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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Distinct sub-cellular autophagy impairments occur independently of protein aggregation in induced neurons from patients with Huntington’s disease

10.1101/2021.03.01.433433 ◽

2021 ◽

Author(s):

Karolina Pircs ◽

Janelle Drouin-Ouellet ◽

Jeovanis Gil ◽

Melinda Rezeli ◽

Daniela A. Grassi ◽

...

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Neurodegenerative Disorder ◽

Direct Reprogramming ◽

Wild Type ◽

Cellular Models ◽

Cellular Autophagy ◽

Age Dependent ◽

Induced Neurons ◽

Neuronal Autophagy

AbstractHuntington’s disease (HD) is a neurodegenerative disorder caused by CAG expansions in the huntingtin (HTT) gene. Modelling HD has remained challenging, as rodent and cellular models poorly recapitulate the disease. To address this, we generated induced neurons (iNs) through direct reprogramming of human skin fibroblasts, which retain age-dependent epigenetic characteristics. HD-iNs displayed profound deficits in autophagy, characterised by reduced transport of late autophagic structures from the neurites to the soma. The neurite-specific alterations in autophagy resulted in shorter, thinner and fewer neurites presented by HD-iNs. CRISPRi-mediated silencing of HTT did not rescue this phenotype but rather resulted in additional autophagy alterations in ctrl-iNs, highlighting the importance of wild type HTT in neuronal autophagy. In summary, our work identifies a distinct subcellular autophagy impairment in aged patient derived HD-neurons and provides a new rational for future development of autophagy activation therapies.

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Identification of Full-Length Wild-Type and Mutant Huntingtin Interacting Proteins by Crosslinking Immunoprecipitation in Mice Brain Cortex

Journal of Huntington s Disease ◽

10.3233/jhd-210476 ◽

2021 ◽

pp. 1-13

Author(s):

Karen A. Sap ◽

Arzu Tugce Guler ◽

Aleksandra Bury ◽

Dick Dekkers ◽

Jeroen A.A. Demmers ◽

...

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Brain Cortex ◽

Full Length ◽

Biological Processes ◽

Interacting Proteins ◽

Mutant Huntingtin ◽

Wild Type ◽

Mutant Huntingtin Protein ◽

Mice Brain

Background: Huntington’s disease is a neurodegenerative disorder caused by a CAG expansion in the huntingtin gene, resulting in a polyglutamine expansion in the ubiquitously expressed mutant huntingtin protein. Objective: Here we set out to identify proteins interacting with the full-length wild-type and mutant huntingtin protein in the mice cortex brain region to understand affected biological processes in Huntington’s disease pathology. Methods: Full-length huntingtin with 20 and 140 polyQ repeats were formaldehyde-crosslinked and isolated via their N-terminal Flag-tag from 2-month-old mice brain cortex. Interacting proteins were identified and quantified by label-free liquid chromatography-mass spectrometry (LC-MS/MS). Results: We identified 30 interactors specific for wild-type huntingtin, 14 interactors specific for mutant huntingtin and 14 shared interactors that interacted with both wild-type and mutant huntingtin, including known interactors such as F8a1/Hap40. Syt1, Ykt6, and Snap47, involved in vesicle transport and exocytosis, were among the proteins that interacted specifically with wild-type huntingtin. Various other proteins involved in energy metabolism and mitochondria were also found to associate predominantly with wild-type huntingtin, whereas mutant huntingtin interacted with proteins involved in translation including Mapk3, Eif3h and Eef1a2. Conclusion: Here we identified both shared and specific interactors of wild-type and mutant huntingtin, which are involved in different biological processes including exocytosis, vesicle transport, translation and metabolism. These findings contribute to the understanding of the roles that wild-type and mutant huntingtin play in a variety of cellular processes both in healthy conditions and Huntington’s disease pathology.

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Abnormal Spinal Cord Myelination due to Oligodendrocyte Dysfunction in a Model of Huntington’s Disease

Journal of Huntington s Disease ◽

10.3233/jhd-210495 ◽

2021 ◽

pp. 1-8

Author(s):

Costanza Ferrari Bardile ◽

Harwin Sidik ◽

Reynard Quek ◽

Nur Amirah Binte Mohammad Yusof ◽

Marta Garcia-Miralles ◽

...

Keyword(s):

Spinal Cord ◽

Huntington's Disease ◽

Huntington’S Disease ◽

Oligodendrocyte Progenitor Cells ◽

Wild Type ◽

Specific Expression ◽

Relative Contribution ◽

Related Proteins ◽

The Impact ◽

Cervical Area

Background: The relative contribution of grey matter (GM) and white matter (WM) degeneration to the progressive brain atrophy in Huntington’s disease (HD) has been well studied. The pathology of the spinal cord in HD is comparatively less well documented. Objective: We aim to characterize spinal cord WM abnormalities in a mouse model of HD and evaluate whether selective removal of mutant huntingtin (mHTT) from oligodendroglia rescues these deficits. Methods: Histological assessments were used to determine the area of GM and WM in the spinal cord of 12-month-old BACHD mice, while electron microscopy was used to analyze myelin fibers in the cervical area of the spinal cord. To investigate the impact of inactivation of mHTT in oligodendroglia on these measures, we used the previously described BACHDxNG2Cre mouse line where mHTT is specifically reduced in oligodendrocyte progenitor cells. Results: We show that spinal GM and WM areas are significantly atrophied in HD mice compared to wild-type controls. We further demonstrate that specific reduction of mHTT in oligodendroglial cells rescues the atrophy of spinal cord WM, but not GM, observed in HD mice. Inactivation of mHTT in oligodendroglia had no effect on the density of oligodendroglial cells but enhanced the expression of myelin-related proteins in the spinal cord. Conclusion: Our findings demonstrate that the myelination abnormalities observed in brain WM structures in HD extend to the spinal cord and suggest that specific expression of mHTT in oligodendrocytes contributes to such abnormalities.

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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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Disposition of Proteins and Lipids in Synaptic Membrane Compartments Is Altered in Q175/Q7 Huntington’s Disease Mouse Striatum

Frontiers in Synaptic Neuroscience ◽

10.3389/fnsyn.2021.618391 ◽

2021 ◽

Vol 13 ◽

Author(s):

Maria Iuliano ◽

Connor Seeley ◽

Ellen Sapp ◽

Erin L. Jones ◽

Callie Martin ◽

...

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Plasma Membranes ◽

Synaptic Function ◽

Synaptic Proteins ◽

Synaptic Membrane ◽

Wild Type ◽

Functional Changes ◽

Mouse Striatum ◽

Old Mice

Dysfunction at synapses is thought to be an early change contributing to cognitive, psychiatric and motor disturbances in Huntington’s disease (HD). In neurons, mutant Huntingtin collects in aggregates and distributes to the same sites as wild-type Huntingtin including on membranes and in synapses. In this study, we investigated the biochemical integrity of synapses in HD mouse striatum. We performed subcellular fractionation of striatal tissue from 2 and 6-month old knock-in Q175/Q7 HD and Q7/Q7 mice. Compared to striata of Q7/Q7 mice, proteins including GLUT3, Na+/K+ ATPase, NMDAR 2b, PSD95, and VGLUT1 had altered distribution in Q175/Q7 HD striata of 6-month old mice but not 2-month old mice. These proteins are found on plasma membranes and pre- and postsynaptic membranes supporting hypotheses that functional changes at synapses contribute to cognitive and behavioral symptoms of HD. Lipidomic analysis of mouse fractions indicated that compared to those of wild-type, fractions 1 and 2 of 6 months Q175/Q7 HD had altered levels of two species of PIP2, a phospholipid involved in synaptic signaling, increased levels of cholesterol ester and decreased cardiolipin species. At 2 months, increased levels of species of acylcarnitine, phosphatidic acid and sphingomyelin were measured. EM analysis showed that the contents of fractions 1 and 2 of Q7/Q7 and Q175/Q7 HD striata had a mix of isolated synaptic vesicles, vesicle filled axon terminals singly or in clusters, and ER and endosome-like membranes. However, those of Q175/Q7 striata contained significantly fewer and larger clumps of particles compared to those of Q7/Q7. Human HD postmortem putamen showed differences from control putamen in subcellular distribution of two proteins (Calnexin and GLUT3). Our biochemical, lipidomic and EM analysis show that the presence of the HD mutation conferred age dependent disruption of localization of synaptic proteins and lipids important for synaptic function. Our data demonstrate concrete biochemical changes suggesting altered integrity of synaptic compartments in HD mice that may mirror changes in HD patients and presage cognitive and psychiatric changes that occur in premanifest 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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