Cdk5 phosphorylation of huntingtin reduces its cleavage by caspases

Huntington's disease (HD) is a neurodegenerative disorder caused by an expanded polyglutamine (polyQ) tract in the huntingtin (htt) protein. Mutant htt toxicity is exposed after htt cleavage by caspases and other proteases release NH2-terminal fragments containing the polyQ expansion. Here, we show htt interacts and colocalizes with cdk5 in cellular membrane fractions. Cdk5 phosphorylates htt at Ser434, and this phosphorylation reduces caspase-mediated htt cleavage at residue 513. Reduced mutant htt cleavage resulting from cdk5 phosphorylation attenuated aggregate formation and toxicity in cells expressing the NH2-terminal 588 amino acids (htt588) of mutant htt. Cdk5 activity is reduced in the brains of HD transgenic mice compared with controls. This result can be accounted for by the polyQ-expanded htt fragments reducing the interaction between cdk5 and its activator p35. These data predict that the ability of cdk5 phosphorylation to protect against htt cleavage, aggregation, and toxicity is compromised in cells expressing toxic fragments of htt.

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Striatal Potassium Channel Dysfunction in Huntington's Disease Transgenic Mice

Journal of Neurophysiology ◽

10.1152/jn.00791.2004 ◽

2005 ◽

Vol 93 (5) ◽

pp. 2565-2574 ◽

Cited By ~ 69

Author(s):

Marjorie A. Ariano ◽

Carlos Cepeda ◽

Christopher R. Calvert ◽

Jorge Flores-Hernández ◽

Elizabeth Hernández-Echeagaray ◽

...

Keyword(s):

Transgenic Mice ◽

Huntington's Disease ◽

Huntington’S Disease ◽

Mouse Models ◽

Neurodegenerative Disorder ◽

Projection Neurons ◽

Electrophysiological Properties ◽

Spiny Neurons ◽

Subunit Expression ◽

Dissociated Cells

Huntington's disease (HD) is a neurodegenerative disorder that mainly affects the projection neurons of the striatum and cerebral cortex. Genetic mouse models of HD have shown that neurons susceptible to the mutation exhibit morphological and electrophysiological dysfunctions before and during development of the behavioral phenotype. We used HD transgenic mouse models to examine inwardly and outwardly rectifying K+ conductances, as well as expression of some related K+ channel subunits. Experiments were conducted in slices and dissociated cells from two mouse models, the R6/2 and TgCAG100, at the beginning and after full development of overt behavioral phenotypes. Striatal medium-sized spiny neurons (MSNs) from symptomatic transgenic mice had increased input resistances, depolarized resting membrane potentials, and reductions in both inwardly and outwardly rectifying K+ currents. These changes were more dramatic in the R6/2 model than in the TgCAG100. Parallel immunofluorescence studies detected decreases in the expression of K+ channel subunit proteins, Kir2.1, Kir2.3, and Kv2.1 in MSNs, which contribute to the formation of the channel ionophores for these currents. Attenuation in K+ conductances and channel subunit expression contribute to altered electrophysiological properties of MSNs and may partially account for selective cellular vulnerability in the striatum.

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A novel imaging ligand as a biomarker for mutant huntingtin-lowering in Huntington's disease

10.1101/2021.07.09.451725 ◽

2021 ◽

Author(s):

Daniele Bertoglio ◽

Jonathan Bard ◽

Manuela Hessmann ◽

Longbin Liu ◽

Annette Gaertner ◽

...

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Neurodegenerative Disorder ◽

Therapeutic Interventions ◽

Non Invasive ◽

Positron Emission ◽

Trinucleotide Expansion ◽

Imaging Markers ◽

The Brain ◽

Polyq Tract

Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder caused by a CAG trinucleotide expansion in the huntingtin (HTT) gene that encodes the pathologic mutant HTT (mHTT) protein with an expanded polyglutamine (PolyQ) tract. While several therapeutic programs targeting mHTT expression have advanced to clinical evaluation, no method is currently available to visualize mHTT levels in the living brain. Here we demonstrate the development of a positron emission tomography (PET) imaging radioligand with high affinity and selectivity for mHTT aggregates. This small molecule radiolabeled with 11C ([11C]CHDI-180R) enables non-invasive monitoring of mHTT pathology in the brain and can track region- and time-dependent suppression of mHTT in response to therapeutic interventions targeting mHTT expression. We further show that therapeutic agents that lower mHTT in the striatum have a functional restorative effect that can be measured by preservation of striatal imaging markers, enabling a translational path to assess the functional effect of mHTT lowering.

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Establishment and maintenance of an R6/1 transgenic mouse colony and validation of its progressive neurological phenotype to study Huntington’s disease

Veterinaria México OA ◽

10.21753/vmoa.5.1.487 ◽

2018 ◽

Vol 5 (1) ◽

Author(s):

Lucía Gabriela García-Lara ◽

Adriana Morales-Martínez ◽

Quetzalli Denisse Angeles-López ◽

Hilda Pedraza-Espitia ◽

Iván Pérez-Neri ◽

...

Keyword(s):

Transgenic Mice ◽

Huntington's Disease ◽

Huntington’S Disease ◽

Transgenic Mouse ◽

Neurodegenerative Disorder ◽

Transgenic Animal ◽

Phenotypic Characteristics ◽

Neurological Phenotype ◽

Transgenic Animal Models ◽

The Central Nervous System

Huntington’s disease (HD) is a hereditary neurodegenerative disorder of the central nervous system that mainly affects the basal ganglia and has no cure. The mutation is located at an abnormal expansion of the CAG triplet in the Huntingtin gene. Humans show psychiatric, behavioural and motor disorders. Transgenic animal models are essential to the study of HD since the disease only affects humans. Therefore, the aim of this article was to describe the formation and maintenance of and to validate the progressive neurological phenotype of an R6/1 transgenic mouse colony. To achieve our objective, the colony founder was imported from Jackson Laboratories, and the mice were kept under controlled environmental conditions. The animals were bred at the vivarium of the Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez. The R6/1 transgenic mice were successfully bred and showed genetic and phenotypic characteristics similar to the ones previously reported. Our colony is currently established and validated with the conditions of our vivarium and has produced more than four generations of R6/1 mice. The establishment of the R6/1 colony and its maintenance through generation is an advantage since it allows us to follow the authenticity of the transgenic mice regarding their phenotypic and motor behaviours. Furthermore, these animals can be compared with other transgenic mice that reproduce some of the main characteristics of the disease manifested in humans, making these transgenic R6/1 mice a useful tool for the study of HD.

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Juvenile Huntington’s Disease Skin Fibroblasts Respond with Elevated Parkin Level and Increased Proteasome Activity as a Potential Mechanism to Counterbalance the Pathological Consequences of Mutant Huntingtin Protein

International Journal of Molecular Sciences ◽

10.3390/ijms20215338 ◽

2019 ◽

Vol 20 (21) ◽

pp. 5338 ◽

Cited By ~ 5

Author(s):

Azzam Aladdin ◽

Róbert Király ◽

Pal Boto ◽

Zsolt Regdon ◽

Krisztina Tar

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Neurodegenerative Disorder ◽

Proteasome Activity ◽

Mitochondrial Fusion ◽

Skin Fibroblasts ◽

Cellular Damage ◽

Huntingtin Protein ◽

Gene And Protein Expression ◽

Polyq Expansion

Huntington’s disease (HD) is an inherited neurodegenerative disorder, caused by an abnormal polyglutamine (polyQ) expansion in the huntingtin protein (Htt). Mitochondrial dysfunction and impairment of the ubiquitin-proteasome system (UPS) are hallmarks of HD neurons. The extraneural manifestations of HD are still unclear. We investigated the crosstalk between mitochondria and proteolytic function in skin fibroblasts from juvenile HD patients. We found reduced mitosis, increased cell size, elevated ROS and increased mitochondrial membrane potential in juvenile HD fibroblasts, while cellular viability was maintained. Mitochondrial OXPHOS analysis did not reveal significant differences compared to control. However, the level of mitochondrial fusion and fission proteins was significantly lower and branching in the mitochondria network was reduced. We hypothesized that juvenile HD fibroblasts counterbalance cellular damage and mitochondrial network deficit with altered proteasome activity to promote cell survival. Our data reveal that juvenile HD fibroblasts exhibit higher proteasome activity, which was associated with elevated gene and protein expression of parkin. Moreover, we demonstrate elevated proteasomal degradation of the mitochondrial fusion protein Mfn1 in diseased cells compared to control cells. Our data suggest that juvenile HD fibroblasts respond to mutant polyQ expansion of Htt with enhanced proteasome activity and faster turnover of specific UPS substrates to protect cells.

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Faculty Opinions recommendation of The HDAC inhibitor 4b ameliorates the disease phenotype and transcriptional abnormalities in Huntington's disease transgenic mice.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1124314.581471 ◽

2008 ◽

Author(s):

Karoly Mirnics

Keyword(s):

Transgenic Mice ◽

Huntington's Disease ◽

Huntington’S Disease ◽

Hdac Inhibitor ◽

Disease Phenotype

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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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Increased calbindin-D28k immunoreactivity in striatal projection neurons of R6/2 Huntington's disease transgenic mice

Neurobiology of Disease ◽

10.1016/j.nbd.2005.05.023 ◽

2005 ◽

Vol 20 (3) ◽

pp. 907-917 ◽

Cited By ~ 7

Author(s):

Z. Sun ◽

H.B. Wang ◽

Y.P. Deng ◽

W.L. Lei ◽

J.P. Xie ◽

...

Keyword(s):

Transgenic Mice ◽

Huntington's Disease ◽

Huntington’S Disease ◽

Projection Neurons ◽

Striatal Projection Neurons ◽

Calbindin D28k

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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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