Huntington's disease: from pathology and genetics to potential therapies

2008 ◽  
Vol 412 (2) ◽  
pp. 191-209 ◽  
Author(s):  
Sara Imarisio ◽  
Jenny Carmichael ◽  
Viktor Korolchuk ◽  
Chien-Wen Chen ◽  
Shinji Saiki ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Trinucleotide Repeat ◽  
Mutant Protein ◽  
Mutant Huntingtin ◽  
Genetic Screens ◽  
Wild Type ◽  
Biological Studies ◽  
Polyglutamine Tract

Huntington's disease (HD) is a devastating autosomal dominant neurodegenerative disease caused by a CAG trinucleotide repeat expansion encoding an abnormally long polyglutamine tract in the huntingtin protein. Much has been learnt since the mutation was identified in 1993. We review the functions of wild-type huntingtin. Mutant huntingtin may cause toxicity via a range of different mechanisms. The primary consequence of the mutation is to confer a toxic gain of function on the mutant protein and this may be modified by certain normal activities that are impaired by the mutation. It is likely that the toxicity of mutant huntingtin is revealed after a series of cleavage events leading to the production of N-terminal huntingtin fragment(s) containing the expanded polyglutamine tract. Although aggregation of the mutant protein is a hallmark of the disease, the role of aggregation is complex and the arguments for protective roles of inclusions are discussed. Mutant huntingtin may mediate some of its toxicity in the nucleus by perturbing specific transcriptional pathways. HD may also inhibit mitochondrial function and proteasome activity. Importantly, not all of the effects of mutant huntingtin may be cell-autonomous, and it is possible that abnormalities in neighbouring neurons and glia may also have an impact on connected cells. It is likely that there is still much to learn about mutant huntingtin toxicity, and important insights have already come and may still come from chemical and genetic screens. Importantly, basic biological studies in HD have led to numerous potential therapeutic strategies.

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

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.

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

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.

scholarly journals The huntingtin inclusion is a dynamic phase-separated compartment

2019 ◽  
Vol 2 (5) ◽  
pp. e201900489 ◽  
Author(s):  
Fahmida Aktar ◽  
Chakkapong Burudpakdee ◽  
Mercedes Polanco ◽  
Sen Pei ◽  
Theresa C Swayne ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Vacuolar Membrane ◽  
Mutant Huntingtin ◽  
Small Particles ◽  
Huntingtin Protein ◽  
Disordered Protein ◽  
Dynamic Phase ◽  
Mutant Huntingtin Protein ◽  
Polyglutamine Tract

Inclusions of disordered protein are a characteristic feature of most neurodegenerative diseases, including Huntington’s disease. Huntington’s disease is caused by expansion of a polyglutamine tract in the huntingtin protein; mutant huntingtin protein (mHtt) is unstable and accumulates in large intracellular inclusions both in affected individuals and when expressed in eukaryotic cells. Using mHtt-GFP expressed in Saccharomyces cerevisiae, we find that mHtt-GFP inclusions are dynamic, mobile, gel-like structures that concentrate mHtt together with the disaggregase Hsp104. Although inclusions may associate with the vacuolar membrane, the association is reversible and we find that inclusions of mHtt in S. cerevisiae are not taken up by the vacuole or other organelles. Instead, a pulse-chase study using photoconverted mHtt-mEos2 revealed that mHtt is directly and continuously removed from the inclusion body. In addition to mobile inclusions, we also imaged and tracked the movements of small particles of mHtt-GFP and determine that they move randomly. These observations suggest that inclusions may grow through the collision and coalescence of small aggregative particles.

scholarly journals Global Rhes knockout in the Q175 Huntington’s disease mouse model

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258486
Author(s):  
Taneli Heikkinen ◽  
Timo Bragge ◽  
Juha Kuosmanen ◽  
Teija Parkkari ◽  
Sanna Gustafsson ◽  
...  
Keyword(s):  
Mouse Model ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
The Body ◽  
Mutant Huntingtin ◽  
Polyglutamine Tract ◽  
Severe Pathology ◽  
Expansion Mutation ◽  
Q175 Mice ◽  
Mixed Gender

Huntington’s disease (HD) results from an expansion mutation in the polyglutamine tract in huntingtin. Although huntingtin is ubiquitously expressed in the body, the striatum suffers the most severe pathology. Rhes is a Ras-related small GTP-binding protein highly expressed in the striatum that has been reported to modulate mTOR and sumoylation of mutant huntingtin to alter HD mouse model pathogenesis. Reports have varied on whether Rhes reduction is desirable for HD. Here we characterize multiple behavioral and molecular endpoints in the Q175 HD mouse model with genetic Rhes knockout (KO). Genetic RhesKO in the Q175 female mouse resulted in both subtle attenuation of Q175 phenotypic features, and detrimental effects on other kinematic features. The Q175 females exhibited measurable pathogenic deficits, as measured by MRI, MRS and DARPP32, however, RhesKO had no effect on these readouts. Additionally, RhesKO in Q175 mixed gender mice deficits did not affect mTOR signaling, autophagy or mutant huntingtin levels. We conclude that global RhesKO does not substantially ameliorate or exacerbate HD mouse phenotypes in Q175 mice.

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.

scholarly journals Restoring GABAergic inhibition rescues memory deficits in a Huntington’s disease mouse model

2018 ◽  
Vol 115 (7) ◽  
pp. E1618-E1626 ◽  
Author(s):  
Zahra Dargaei ◽  
Jee Yoon Bang ◽  
Vivek Mahadevan ◽  
C. Sahara Khademullah ◽  
Simon Bedard ◽  
...  
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Learning And Memory ◽  
Cognitive Impairments ◽  
Memory Deficits ◽  
Gabaergic Inhibition ◽  
Wild Type ◽  
Excitatory Action ◽  
Excitatory Gaba

Huntington’s disease (HD) is classically characterized as a movement disorder, however cognitive impairments precede the motor symptoms by ∼15 y. Based on proteomic and bioinformatic data linking the Huntingtin protein (Htt) and KCC2, which is required for hyperpolarizing GABAergic inhibition, and the important role of inhibition in learning and memory, we hypothesized that aberrant KCC2 function contributes to the hippocampal-associated learning and memory deficits in HD. We discovered that Htt and KCC2 interact in the hippocampi of wild-type and R6/2-HD mice, with a decrease in KCC2 expression in the hippocampus of R6/2 and YAC128 mice. The reduced expression of the Cl−-extruding cotransporter KCC2 is accompanied by an increase in the Cl−-importing cotransporter NKCC1, which together result in excitatory GABA in the hippocampi of HD mice. NKCC1 inhibition by the FDA-approved NKCC1 inhibitor bumetanide abolished the excitatory action of GABA and rescued the performance of R6/2 mice on hippocampal-associated behavioral tests.

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