alpha-synuclein and Huntington-Disease

Amyloid aggregation, which disrupts protein homeostasis, is a common pathological event occurring in human neurodegenerative diseases (NDs). Numerous evidences have shown that the structural diversity, so-called polymorphism, is decisive to the amyloid pathology and is closely associated with the onset, progression, and phenotype of ND. But how could one protein form so many stable structures? Recently, atomic structural evidence has been rapidly mounting to depict the involvement of chemical modifications in the amyloid fibril formation. In this Perspective, we aim to present a hierarchical regulation of chemical modifications including covalent post-translational modifications (PTMs) and noncovalent cofactor binding in governing the polymorphic amyloid formation, based mainly on the latest α-synuclein and Tau fibril structures. We hope to emphasize the determinant role of chemical modifications in amyloid assembly and pathology and to evoke chemical biological approaches to lead the fundamental and therapeutic research on protein amyloid state and the associated NDs.

Topics: Acetylation; alpha-Synuclein; Alzheimer Disease; Amyloid; DNA-Binding Proteins; Humans; Huntington Disease; Models, Molecular; Parkinson Disease; Phosphorylation; Poly Adenosine Diphosphate Ribose; Protein Aggregates; Protein Binding; Protein Interaction Domains and Motifs; Protein Processing, Post-Translational; Protein Structure, Secondary; tau Proteins

Amyloidosis is a concept that implicates disorders and complications that are due to abnormal protein accumulation in different cells and tissues. Protein aggregation-associated diseases are classified according to the type of aggregates and deposition sites, such as neurodegenerative disorders and type 2 diabetes mellitus. Polyphenolic phytochemicals such as curcumin and its derivatives have anti-amyloid effects both in vitro and in animal models; however, the underlying mechanisms are not understood. In this review, we summarized possible mechanisms by which curcumin could interfere with self-assembly processes and reduce amyloid aggregation in amyloidosis. Furthermore, we discuss clinical trials in which curcumin is used as a therapeutic agent for the treatment of diseases linking to protein aggregates.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid beta-Peptides; Amyloidosis; Clinical Trials as Topic; Creutzfeldt-Jakob Syndrome; Curcumin; Diabetes Mellitus, Type 2; Humans; Huntington Disease; Hypoglycemic Agents; Mitochondria; Neuroprotective Agents; Oxidative Stress; Parkinson Disease; Protein Aggregates; tau Proteins

Most neurodegenerative diseases are characterized by the intracellular or extracellular aggregation of misfolded proteins such as amyloid-β and tau in Alzheimer disease, α-synuclein in Parkinson disease, and TAR DNA-binding protein 43 in amyotrophic lateral sclerosis. Accumulating evidence from both human studies and disease models indicates that intercellular transmission and the subsequent templated amplification of these misfolded proteins are involved in the onset and progression of various neurodegenerative diseases. The misfolded proteins that are transferred between cells are referred to as 'pathological seeds'. Recent studies have made exciting progress in identifying the characteristics of different pathological seeds, particularly those isolated from diseased brains. Advances have also been made in our understanding of the molecular mechanisms that regulate the transmission process, and the influence of the host cell on the conformation and properties of pathological seeds. The aim of this Review is to summarize our current knowledge of the cell-to-cell transmission of pathological proteins and to identify key questions for future investigation.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid beta-Peptides; Amyotrophic Lateral Sclerosis; Axonal Transport; Brain; Cell Communication; DNA-Binding Proteins; Endocytosis; Exosomes; Genetic Predisposition to Disease; Humans; Huntingtin Protein; Huntington Disease; Membrane Fusion; Nanotubes; Neurodegenerative Diseases; Neuroglia; Neurons; Parkinson Disease; Protein Aggregation, Pathological; Protein Transport; tau Proteins

Mosaicism, the presence of genomic differences between cells due to post-zygotic somatic mutations, is widespread in the human body, including within the brain. A role for this in neurodegenerative diseases has long been hypothesised, and technical developments are now allowing the question to be addressed in detail. The rapidly accumulating evidence is discussed in this review, with a focus on recent developments. Somatic mutations of numerous types may occur, including single nucleotide variants (SNVs), copy number variants (CNVs), and retrotransposon insertions. They could act as initiators or risk factors, especially if they arise in development, although they could also result from the disease process, potentially contributing to progression. In common sporadic neurodegenerative disorders, relevant mutations have been reported in synucleinopathies, comprising somatic gains of SNCA in Parkinson's disease and multiple system atrophy, and in Alzheimer's disease, where a novel recombination mechanism leading to somatic variants of APP, as well as an excess of somatic SNVs affecting tau phosphorylation, have been reported. In Mendelian repeat expansion disorders, mosaicism due to somatic instability, first detected 25 years ago, has come to the forefront. Brain somatic SNVs occur in DNA repair disorders, and there is evidence for a role of several ALS genes in DNA repair. While numerous challenges, and need for further validation, remain, this new, or perhaps rediscovered, area of research has the potential to transform our understanding of neurodegeneration.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid beta-Protein Precursor; Amyotrophic Lateral Sclerosis; DNA Copy Number Variations; DNA Repair-Deficiency Disorders; DNA Repeat Expansion; Humans; Huntington Disease; Mosaicism; Multiple System Atrophy; Mutagenesis, Insertional; Mutation; Neurodegenerative Diseases; Parkinson Disease; Phosphorylation; Polymorphism, Single Nucleotide; Retroelements; Synucleinopathies; tau Proteins

Juvenile parkinsonism is arbitrarily defined as parkinsonian symptoms and signs presenting prior to 21 years of age. Levodopa-responsive juvenile parkinsonism that is consistent with diagnostic criteria for Parkinson's disease is most often caused by mutations in the PARK-Parkin, PARK-PINK1, or PARK-DJ1 genes. However, many other genetic and acquired parkinsonian disorders presenting in childhood or young adulthood are being reported, often with atypical features, such as presence of other movement disorders, cognitive decline, and psychiatric symptoms. The genetic landscape of juvenile parkinsonism is rapidly changing with the discovery of new genes. Although the mainstay of treatment remains levodopa, other symptomatic therapies such as botulinum toxin for focal dystonia, supportive medical therapies, and deep brain stimulation in select cases, may also be used to provide the most optimal long-term outcomes. Since the topic has not been reviewed recently, we aim to provide an update on genetics, differential diagnosis, evaluation, and treatment of juvenile parkinsonism.

Topics: Adolescent; alpha-Synuclein; Antiparkinson Agents; Child; Child, Preschool; Deep Brain Stimulation; Diagnosis, Differential; DiGeorge Syndrome; Dystonic Disorders; Genetic Diseases, X-Linked; Hepatolenticular Degeneration; Humans; Huntington Disease; Levodopa; Parkinsonian Disorders; Protein Deglycase DJ-1; Protein Kinases; Spinocerebellar Ataxias; Ubiquitin-Protein Ligases; Young Adult

Several neurodegenerative disorders, such as Alzheimer's and Parkinson's disease, are characterized by prominent loss of synapses and neurons associated with the presence of abnormally structured or misfolded protein assemblies. Cell-to-cell transfer of misfolded proteins has been proposed for the intra-cerebral propagation of these diseases. When released, misfolded proteins diffuse in the 3D extracellular space before binding to the plasma membrane of neighboring cells, where they diffuse on a 2D plane. This reduction in diffusion dimension and the cell surface molecular crowding promote deleterious interactions with native membrane proteins, favoring clustering and further aggregation of misfolded protein assemblies. These processes open up new avenues for therapeutics development targeting the initial interactions of deleterious proteins with the plasma membrane or the subsequent pathological signaling.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid beta-Peptides; Amyotrophic Lateral Sclerosis; Animals; Cell Membrane; Extracellular Space; Humans; Huntingtin Protein; Huntington Disease; Neurodegenerative Diseases; Parkinson Disease; Prions; Protein Aggregation, Pathological; Protein Folding; Protein Transport; Superoxide Dismutase-1; tau Proteins

Among the diseases affecting the central nervous system (CNS), neurodegenerations attract the interest of both the clinician and the medicinal chemist. The increasing average age of population, the growing number of patients, and the lack of long-term effective remedies push ahead the quest for novel tools against this class of pathologies. We present a review on the state of the art of the molecules (or combination of molecules) of natural origin that are currently under study against two well-defined pathologies: Parkinson's disease (PD) and Huntington's disease (HD). Nowadays, very few tools are available for preventing or counteracting the progression of such diseases. Two major parameters were considered for the preparation of this review: particular attention was reserved to these research works presenting well-defined molecular mechanisms for the studied compounds, and where available, papers reporting in vivo data were preferred. A literature search for peer-reviewed articles using PubMed, Scopus, and Reaxys databases was performed, exploiting different keywords and logical operators: 91 papers were considered (preferentially published after 2015). The review presents a brief overview on the etiology of the studied neurodegenerations and the current treatments, followed by a detailed discussion of the natural and semisynthetic compounds dividing them in different paragraphs considering their several mechanisms of action.

Topics: alpha-Synuclein; Animals; Anti-Dyskinesia Agents; Antioxidants; Antiparkinson Agents; Autophagy; Biological Products; Dementia; Dopamine; Drug Discovery; Drug Evaluation, Preclinical; Humans; Huntington Disease; Microglia; Mitochondria; Molecular Targeted Therapy; Monoamine Oxidase Inhibitors; Oxidative Stress; Parkinson Disease; Plant Preparations; Protein Aggregation, Pathological; Signal Transduction

The role of autophagy in cell survival and suppression of neurodegeneration was considered. We discussed its involvement in Alzheimer's, Parkinson's, and Huntington's diseases connected with accumulation of amy- loid-β, α-synuclein, and huntingtin, respectively. Autophagy is reduced in these diseases and in aging as well to various extent. Elimination of accumulated toxic proteins and structures is performed by autophagy mech- anisms (chaperon-mediated autophagy, macroautophagy, selected autophagy) in an interaction with ubiqui- tin-proteasome system. In many cases activation of mTOR-dependent autophagy and mTOR-independent regulatory pathways lead to the therapeutic effect of inhibition of neurodegeneration in cell cultures and an- imal models. Some autophagy enhancers such as resveratrol, metformin, rilmenidine, lithium, and curcumin are tested now in clinical trials.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid beta-Peptides; Animals; Autophagy; Clinical Trials as Topic; Gene Expression Regulation; Humans; Huntingtin Protein; Huntington Disease; Metformin; Molecular Chaperones; Molecular Targeted Therapy; Neuroprotective Agents; Parkinson Disease; Proteasome Endopeptidase Complex; Sirolimus; TOR Serine-Threonine Kinases; Ubiquitin

Mammalian cells remove misfolded proteins using various proteolytic systems, including the ubiquitin (Ub)-proteasome system (UPS), chaperone mediated autophagy (CMA) and macroautophagy. The majority of misfolded proteins are degraded by the UPS, in which Ub-conjugated substrates are deubiquitinated, unfolded and cleaved into small peptides when passing through the narrow chamber of the proteasome. The substrates that expose a specific degradation signal, the KFERQ sequence motif, can be delivered to and degraded in lysosomes via the CMA. Aggregation-prone substrates resistant to both the UPS and the CMA can be degraded by macroautophagy, in which cargoes are segregated into autophagosomes before degradation by lysosomal hydrolases. Although most misfolded and aggregated proteins in the human proteome can be degraded by cellular protein quality control, some native and mutant proteins prone to aggregation into β-sheet-enriched oligomers are resistant to all known proteolytic pathways and can thus grow into inclusion bodies or extracellular plaques. The accumulation of protease-resistant misfolded and aggregated proteins is a common mechanism underlying protein misfolding disorders, including neurodegenerative diseases such as Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD), prion diseases and Amyotrophic Lateral Sclerosis (ALS). In this review, we provide an overview of the proteolytic pathways in neurons, with an emphasis on the UPS, CMA and macroautophagy, and discuss the role of protein quality control in the degradation of pathogenic proteins in neurodegenerative diseases. Additionally, we examine existing putative therapeutic strategies to efficiently remove cytotoxic proteins from degenerating neurons.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid beta-Peptides; Amyotrophic Lateral Sclerosis; Animals; Autophagy; DNA-Binding Proteins; Humans; Huntingtin Protein; Huntington Disease; Lysosomes; Molecular Targeted Therapy; Mutation; Nerve Tissue Proteins; Neurodegenerative Diseases; Parkinson Disease; Prion Diseases; Proteasome Endopeptidase Complex; Proteolysis; Proteostasis Deficiencies; PrPSc Proteins; Superoxide Dismutase; tau Proteins; Ubiquitin

The neurodegenerative diseases described in this volume, as well as many nonneurodegenerative diseases, are characterized by deposits known as amyloid. Amyloid has long been associated with these various diseases as a pathological marker and has been implicated directly in the molecular pathogenesis of disease. However, increasing evidence suggests that these proteinaceous Congo red staining deposits may not be toxic or destructive of tissue. Recent studies strongly implicate smaller aggregates of amyloid proteins as the toxic species underlying these neurodegenerative diseases. Despite the outward obvious differences among these clinical syndromes, there are some striking similarities in their molecular pathologies. These include dysregulation of intracellular calcium levels, impairment of mitochondrial function, and the ability of virtually all amyloid peptides to form ion-permeable pores in lipid membranes. Pore formation is enhanced by environmental factors that promote protein aggregation and is inhibited by agents, such as Congo red, which prevent aggregation. Remarkably, the pores formed by a variety of amyloid peptides from neurodegenerative and other diseases share a common set of physiologic properties. These include irreversible insertion of the pores in lipid membranes, formation of heterodisperse pore sizes, inhibition by Congo red of pore formation, blockade of pores by zinc, and a relative lack of ion selectivity and voltage dependence. Although there exists some information about the physical structure of these pores, molecular modeling suggests that 4-6-mer amyloid subunits may assemble into 24-mer pore-forming aggregates. The molecular structure of these pores may resemble the β-barrel structure of the toxics pore formed by bacterial toxins, such as staphylococcal α-hemolysin, anthrax toxin, and Clostridium perfringolysin.

Topics: alpha-Synuclein; Amyloid beta-Peptides; Animals; Cell Membrane; Humans; Huntington Disease; Mice; Mitochondrial Membranes; Models, Neurological; Neurodegenerative Diseases; Neurons; Prions; Protein Conformation

Classically, Parkinson's disease (PD) is linked to dopamine neuron death in the substantia nigra pars compacta. Intracytoplasmic protein inclusions named Lewy bodies, and corresponding Lewy neurites found in neuronal processes, are also key features of the degenerative process in the substantia nigra. The molecular mechanisms by which substantia nigra dopamine neurons die and whether the Lewy pathology is directly involved in the cell death pathway are open questions. More recently, it has become apparent that Lewy pathology gradually involves greater parts of the PD brain and is widespread in late stages. In this review, we first discuss the role of misfolded α-synuclein protein, which is the main constituent of Lewy bodies, in the pathogenesis of PD. We then describe recent evidence that α-synuclein might transfer between cells in PD brains. We discuss in detail the possible molecular mechanisms underlying the proposed propagation and the likely consequences for cells that take up α-synuclein. Finally, we focus on aspects of the pathogenic process that could be targeted with new pharmaceutical therapies or used to develop biomarkers for early PD detection.

Topics: alpha-Synuclein; Alzheimer Disease; Amyotrophic Lateral Sclerosis; Cell Death; Dopamine; Humans; Huntington Disease; Lewy Bodies; Mutation; Neurites; Neurons; Parkinson Disease; Protein Folding; Protein Transport; Substantia Nigra

The molecular chaperone Hsp104 plays a central role in the clearance of aggregates after heat shock and the propagation of yeast prions. Hsp104's disaggregation activity and prion propagation have been linked to its ability to resolubilize or remodel protein aggregates. However, Hsp104 has also the capacity to catalyze protein aggregation of some substrates at specific conditions. Hence, it is a molecular chaperone with two opposing activities with respect to protein aggregation. In yeast models of Huntington's disease, Hsp104 is required for the aggregation and toxicity of polyglutamine (polyQ), but the expression of Hsp104 in cellular and animal models of Huntington's and Parkinson's disease protects against polyQ and alpha-synuclein toxicity. Therefore, elucidating the molecular determinants and mechanisms underlying the ability of Hsp104 to switch between these two activities is of critical importance for understanding its function and could provide insight into novel strategies aimed at preventing or reversing the formation of toxic protein aggregation in systemic and neurodegenerative protein misfolding diseases. Here, we present an overview of the current molecular models and hypotheses that have been proposed to explain the role of Hsp104 in modulating protein aggregation and prion propagation. The experimental approaches and the evidences presented so far in relation to these models are examined. Our primary objective is to offer a critical review that will inspire the use of novel techniques and the design of new experiments to proceed towards a qualitative and quantitative understanding of the molecular mechanisms underlying the multifunctional properties of Hsp104 in vivo.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid; Animals; Fungal Proteins; Heat-Shock Proteins; Humans; Huntington Disease; Models, Molecular; Mutation; Parkinson Disease; Peptides; Prion Diseases; Prions; Protein Conformation; Protein Folding

The term neurodegenerative disorders, encompasses a variety of underlying conditions, sporadic and/or familial and are characterized by the persistent loss of neuronal subtypes. These disorders can disrupt molecular pathways, synapses, neuronal subpopulations and local circuits in specific brain regions, as well as higher-order neural networks. Abnormal network activities may result in a vicious cycle, further impairing the integrity and functions of neurons and synapses, for example, through aberrant excitation or inhibition. The most common neurodegenerative disorders are Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis and Huntington's disease. The molecular features of these disorders have been extensively researched and various unique neurotherapeutic interventions have been developed. However, there is an enormous coercion to integrate the existing knowledge in order to intensify the reliability with which neurodegenerative disorders can be diagnosed and treated. The objective of this review article is therefore to assimilate these disorders' in terms of their neuropathology, neurogenetics, etiology, trends in pharmacological treatment, clinical management, and the use of innovative neurotherapeutic interventions.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid beta-Peptides; Amyotrophic Lateral Sclerosis; Anticonvulsants; Antipsychotic Agents; Cholinergic Antagonists; Dopamine Agents; Humans; Huntingtin Protein; Huntington Disease; Nerve Tissue Proteins; Neurodegenerative Diseases; Neurons; Parkinson Disease; tau Proteins

Budding yeast Saccharomyces cerevisiae has proven to be a valuable model organism for studying fundamental cellular processes across the eukaryotic kingdom including man. In this respect, complementation assays, in which the yeast protein is replaced by a homologous protein from another organism, have been very instructive. A newer trend is to use the yeast cell factory as a toolbox to understand cellular processes controlled by proteins for which the yeast lacks functional counterparts. An increasing number of studies have indicated that S. cerevisiae is a suitable model system to decipher molecular mechanisms involved in a variety of neurodegenerative disorders caused by aberrant protein folding. Here we review the current knowledge gained by the use of so-called humanized yeasts in the field of Huntington's, Parkinson's and Alzheimer's diseases.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid beta-Peptides; Apoptosis; Apoptosis Regulatory Proteins; Heat-Shock Proteins; Humans; Huntingtin Protein; Huntington Disease; Models, Biological; Nerve Degeneration; Nerve Tissue Proteins; Nuclear Proteins; Parkinson Disease; Peptides; Protein Folding; Saccharomyces cerevisiae; tau Proteins; Yeasts

Parkinson's disease (PD) is a common neurodegenerative disorder of adulthood characterized clinically by rigidity, bradykinesia, resting tremor, and postural instability. The annual incidence of PD ranges between 16 and 19 individuals per 100,000 (Twelves et al., Mov Disord 2003;18:19-31). Historically, PD has been commonly viewed as an idiopathic or environmentally triggered condition. However, as is true with most common conditions, there have been several families reported with PD who demonstrate a classic Mendelian pattern of inheritance. To date, nine genetic loci have been reported and four pathogenic genes have been identified: alpha-synuclein, parkin, DJ1, and PINK1. Families with alterations in these genes or linked sites demonstrate either recessive or dominant inheritance patterns and may have typical and/or atypical symptoms, with an age of onset extending from the second to the sixth decade. Commercial tests for parkin and alpha-synuclein mutations are now available. We predict that physicians, particularly neurologists, increasingly will be approached for information and referrals regarding genetic testing. To assist patients and their families, physicians will not only need to know when such testing is likely to yield a meaningful result but also be aware of the possible social and emotional consequences of testing. The following is a review of what is currently known about the genetics of PD within this context. We discuss what is known about genetic testing for Huntington's disease, a well-described model for genetic testing in a neurodegenerative disorder. We explore the utility, appropriateness, and possible implications of genetic testing for diagnostic and presymptomatic purposes.

Topics: alpha-Synuclein; Family Health; Humans; Huntington Disease; Intracellular Signaling Peptides and Proteins; Molecular Diagnostic Techniques; Nerve Tissue Proteins; Oncogene Proteins; Parkinson Disease; Protein Deglycase DJ-1; Protein Kinases; Synucleins; Ubiquitin-Protein Ligases

Defective handling of proteins is a central feature of major neurodegenerative diseases. The discovery that neuronal dysfunction or degeneration can be caused by mutations in single cellular proteins has given new opportunities to model the underlying disease processes by genetic modification of cells in vitro or by generation of transgenic animals carrying the disease-causing gene. Recent developments in recombinant viral-vector technology have opened up an interesting alternative possibility, based on direct gene transfer to selected subregions or subsets of neurons in the brain. Using the highly efficient adeno-associated virus or lentivirus vectors, recent reports have shown that overexpression of mutated human huntingtin or alpha-synuclein in neurons in the striatum or substantia nigra induces progressive neuropathology and neurodegeneration, similar to that seen in Huntington's and Parkinson's diseases. Targeted overexpression of disease-causing genes by recombinant viral vectors provides a new and highly flexible approach for in vivo modeling of neurodegenerative diseases, not only in mice and rats but also in primates.

Topics: alpha-Synuclein; Animals; Animals, Genetically Modified; Central Nervous System; Corpus Striatum; Dependovirus; Disease Models, Animal; Gene Transfer Techniques; Genetic Vectors; Huntingtin Protein; Huntington Disease; Lentivirus; Mutation; Nerve Degeneration; Nerve Tissue Proteins; Neurons; Nuclear Proteins; Parkinson Disease; Substantia Nigra; Synucleins

Linkage of the Huntington's disease gene to chromosome 4 in 1983 marked the birth of modern genetics in movement disorders. The discovery that an expanded trinucleotide DNA repeat was central to the mechanism of this disease has been repeated over and over in a growing list of inherited ataxias. In 1997, a different mutation and genetic mechanism was discovered in a severe type of generalized primary torsion dystonia - Oppenheim's dystonia. Before this, only the genetic cause for rare metabolic dystonias was known, notably dopa-responsive (Segawa's) dystonia. In the same year, from the identification of mutation in the alpha-synuclein gene in rare pedigrees with autosomal dominant parkinsonism, arose the concept that Parkinson's disease may be part of a broader group of 'synucleinopathies', in which there is a fundamental defect in protein processing. In the following year, mutations in autosomal recessive juvenile onset parkinsonism were found in a gene called 'parkin'. Parkin mutations are a more common cause of parkinsonism than the rare alpha-synuclein mutations, particularly in young-onset disease. However, a most important understanding, occurring in the last year, has been the relationship between the parkin gene product, alpha-synuclein and abnormal protein degradation in the cell. A unified theory of neuronal death in Parkinson's disease is emerging, pointing to potential new therapies in the future.

Topics: alpha-Synuclein; Carrier Proteins; Chromosome Mapping; Chromosomes, Human; Dystonic Disorders; Friedreich Ataxia; Genes, Dominant; Genes, Recessive; Humans; Huntingtin Protein; Huntington Disease; Ligases; Minisatellite Repeats; Molecular Chaperones; Movement Disorders; Nerve Tissue Proteins; Nuclear Proteins; Parkinson Disease; Spinocerebellar Ataxias; Synucleins; Ubiquitin-Protein Ligases

Protein oxidation, one of a number of brain biomarkers of oxidative stress, is increased in several age-related neurodegenerative disorders or animal models thereof, including Alzheimer's disease, Huntington's disease, prion disorders, such as Creutzfeld-Jakob disease, and alpha-synuclein disorders, such as Parkinson's disease and frontotemporal dementia. Each of these neurodegenerative disorders is associated with aggregated proteins in brain. However, the relationship among protein oxidation, protein aggregation, and neurodegeneration remain unclear. The current rapid progress in elucidation of mechanisms of protein oxidation in neuronal loss should provide further insight into the importance of free radical oxidative stress in these neurodegenerative disorders.

Topics: Aging; alpha-Synuclein; Alzheimer Disease; Animals; Brain; Humans; Huntington Disease; Nerve Tissue Proteins; Neurodegenerative Diseases; Oxidation-Reduction; Prion Diseases; Synucleins

Huntington's disease (HD) is a neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the HTT gene for which no therapies are available. HTT mutation causes protein misfolding and aggregation, preferentially affecting medium spiny neurons (MSNs) of the basal ganglia. Transcriptional perturbations in synaptic genes and neuroinflammation are key processes that precede MSN dysfunction and motor symptom onset. Understanding the interplay between these processes is crucial to develop effective therapeutic strategies to treat HD. We investigated the role of protein kinase CK2α', a kinase upregulated in MSNs in HD and previously associated with Parkinson's disease (PD), in the regulation of neuroinflammation and synaptic function in HD. We used the heterozygous knock-in zQ175 HD mouse model and compared that to zQ175 mice lacking one allele of CK2α' (zQ175:CK2α'

Topics: alpha-Synuclein; Animals; Casein Kinase II; Corpus Striatum; Disease Models, Animal; Humans; Huntington Disease; Mice; Neurons

Recent evidence suggests a potential role for mixed proteinopathies in the development of clinical manifestations in patients with Huntington's disease (HD). A possible cross-talk between mutant huntingtin and α-synuclein aggregates has been postulated. Serum α-synuclein has been evaluated as a potential biomarker in patients with Parkinson's disease (PD). We presently sought to investigate serum α-synuclein levels in 38 HD patients (34 symptomatic and 4 premanifest) and compare them to 36 controls. We found that α-synuclein was elevated in HD patients vs. controls (2.49 ± 1.47 vs. 1.40 ± 1.16, p = 0.001). There was no difference in α-synuclein levels between symptomatic vs. premanifest HD, nor between HD patients receiving medication vs. treatment-naïve. Furthermore, α-synuclein levels showed no correlation with CAG2, Unified HD Rating Scale (UHDRS) motor score, age, disease duration or disease burden score. Our results provide evidence for elevated serum α-synuclein in HD and lend support to further investigating the role of α-synuclein in this disorder.

Topics: alpha-Synuclein; Humans; Huntington Disease; Parkinson Disease

Accumulating evidence highlights the potential role of mixed proteinopathies (i.e., abnormal protein aggregation) in the development of clinical manifestations of neurodegenerative diseases (NDD). Huntington's disease (HD) is an inherited NDD caused by autosomal-dominant expanded CAG trinucleotide repeat mutation in the gene coding for Huntingtin (Htt). Previous studies have suggested the coexistence of phosphorylated-Tau, α-synuclein (α-Syn) and TAR DNA-binding protein 43 (TDP-43) inclusions in HD. However, definite evidence that HD pathology in humans can be accompanied by other proteinopathies is still lacking. Using human post-mortem putamen samples from 31 controls and 56 HD individuals, we performed biochemical analyses of the expression, oligomerization and aggregation of Tau, α-Syn, TDP-43, and Amyloid precursor protein (APP)/Aβ. In HD brain, we observed reduced soluble protein (but not mRNA) levels of Htt, α-Syn, and Tau. Our results also support abnormal phosphorylation of Tau in more advanced stages of disease. Aberrant splicing of Tau exons 2, 3 (exclusion) and 10 (inclusion) was also detected in HD patients, leading to higher 0N4R and lower 1N3R isoforms. Finally, following formic acid extraction, we observed increased aggregation of TDP-43, α-Syn, and phosphorylated-Tau during HD progression. Notably, we observed that 88% of HD patients with Vonsattel grade 4 neuropathology displayed at least one non-Htt proteinopathy compared to 29% in controls. Interestingly, α-Syn aggregation correlated with Htt, TDP-43 and phosphorylated-Tau in HD but not in controls. The impact of this work is twofold: (1) it provides compelling evidences that Tau, α-Syn and TDP-43 proteinopathies are increased in HD, and (2) it suggests the involvement of common mechanisms leading to abnormal accumulation of aggregation-prone proteins in NDD. Further studies will be needed to decipher the impact of these proteinopathies on clinical manifestation of HD.

Topics: Adult; Aged; Aged, 80 and over; alpha-Synuclein; Amyloid beta-Protein Precursor; Cohort Studies; DNA-Binding Proteins; Female; Humans; Huntingtin Protein; Huntington Disease; Male; Middle Aged; Phosphorylation; Proteostasis Deficiencies; Putamen; RNA Splicing; RNA, Messenger; tau Proteins

The polyglutamine (polyQ) diseases, such as Huntington's disease and the spinocerebellar ataxias, are characterized by the accumulation of elongated polyQ sequences (epolyQ) and mostly occur during midlife. Considering that polyQ disorders have not been selected out in evolution, there might be important physiological functions of epolyQ during development and/or reproduction. In a similar context, the physiological functions of neurodegeneration-associated amyloidogenic proteins (APs), such as β-amyloid in Alzheimer's disease and α-synuclein in Parkinson's disease, remain elusive. In this regard, we recently proposed that evolvability for coping with diverse stressors in the brain, which is beneficial for offspring, might be relevant to the physiological functions of APs. Given analogous properties of APs and epolyQ in terms of neurotoxic amyloid-fibril formation, the objective of this paper is to determine whether evolvability could also be applied to the physiological functions of epolyQ. Indeed, APs and epolyQ are similar in many ways, including functional redundancy of non-amyloidogenic homologues, hormesis conferred by the heterogeneity of the stress-induced protein aggregates, the transgenerational prion-like transmission of the protein aggregates via germ cells, and the antagonistic pleiotropy relationship between evolvability and neurodegenerative disease. Given that epolyQ is widely expressed from microorganisms to human brain, whereas APs are only identified in vertebrates, evolvability of epolyQ is considered to be much more primitive compared to those of APs during evolution. Collectively, epolyQ may be not only be important in the pathophysiology of polyQ diseases, but also in the evolution of amyloid-related evolvability.

Topics: alpha-Synuclein; Alzheimer Disease; Amyloid; Amyloid beta-Peptides; Bulbo-Spinal Atrophy, X-Linked; Evolution, Molecular; Genetic Pleiotropy; Humans; Huntington Disease; Machado-Joseph Disease; Myoclonic Epilepsies, Progressive; Parkinson Disease; Peptides; Spinocerebellar Ataxias; Trinucleotide Repeat Expansion

Autophagy-lysosomal pathway is a cellular protective system to remove aggregated proteins and damaged organelles. Meanwhile, exosome secretion has emerged as a mode to selectively clear the neurotoxic proteins, such as α-synuclein. Mounting evidence suggests that these two cellular processes are coordinated to facilitate the clearance of toxic cellular waste; however the regulators for the transition between these two processes are unclear. Here we show that SCAMP5, a secretory carrier membrane protein significantly induced in the brains of Huntington's disease patients, is quickly and transiently induced by protein stress and autophagic stimulation, and is regulated by the master autophagy transcriptional regulator TFEB. Ironically, SCAMP5 inhibits autophagy flux by blocking the fusion of autophagosomes and lysosomes. Although autophagy is blocked, SCAMP5 does not cause significant protein aggregation in cells. Instead, it promotes the Golgi fragmentation and stimulates the unconventional secretion of the co-localizing α-synuclein via exosome as an exosome component. Therefore, we have identified SCAMP5 as a novel coordinator of autophagy and exosome secretion, which is induced upon protein stress to channel the efficient clearance of toxic proteins via the exosomes rather than autophagy-lysosomal pathway.

Topics: alpha-Synuclein; Autophagy; Carrier Proteins; Cell Line; Exosomes; Fluorescent Antibody Technique; Golgi Apparatus; Humans; Huntington Disease; Immunoblotting; Immunoprecipitation; Lysosomes; Membrane Proteins; Parkinson Disease; RNA, Small Interfering

The pathological hallmark of Huntington disease (HD) is the intracellular aggregation of mutant huntingtin (mHTT) in striatal neurons and glia associated with the selective loss of striatal medium-sized spiny neurons. Up to the present, the role of glia in HD is poorly understood and has been classically considered secondary to neuronal disorder. Trehalose is a disaccharide known to possess many pharmacological properties, acting as an antioxidant, a chemical chaperone, and an inducer of autophagy. In this study, we analyzed at an early postnatal development stage the abnormalities observed in striatal glial cell cultures of postnatal R6/1 mice (HD glia), under baseline and stressing conditions and the protective effects of trehalose. Our data demonstrate that glial HD alterations already occur at early stages of postnatal development. After 20 postnatal days in vitro, striatal HD glia cultures showed more reactive astrocytes with increased expression of glial fibrillary acidic protein (GFAP) but with less replication capacity, less A2B5(+) glial progenitors and more microglia than wild-type (WT) cultures. HD glia had lower levels of intracellular glutathione (GSH) and was more susceptible to H2O2 and epoxomicin insults. The amount of expressed GDNF and secreted mature-BDNF by HD astrocytes were much lower than by WT astrocytes. In addition, HD glial cultures showed a deregulation of the major proteolytic systems, the ubiquitin-proteasomal system (UPS), and the autophagic pathway. This produces a defective protein quality control, indicated by the elevated levels of ubiquitination and p62 protein. Interestingly, we show that trehalose, through its capacity to induce autophagy, inhibited p62/SQSTM1 accumulation and facilitated the degradation of cytoplasmic aggregates from mHTT and α-synuclein proteins. Trehalose also reduced microglia activation and reversed the disrupted cytoskeleton of astrocytes accompanied with an increase in the replication capacity. In addition, trehalose up-regulated mature-BDNF neurotrophic factor expression and secretion, probably mediating cytoskeletal organization and helping in vesicular BDNF transport. Together, these findings indicate that glia suffers functional early changes in the disease process, changes that may contribute to HD neurodegeneration. Trehalose could be a very promising compound for treatment of HD and other diseases with abnormal protein aggregates. Furthermore our study identifies glial cells as a novel t

Topics: alpha-Synuclein; Animals; Brain-Derived Neurotrophic Factor; Cells, Cultured; Corpus Striatum; Cytoskeleton; Female; Glial Cell Line-Derived Neurotrophic Factor; Gliosis; Humans; Huntingtin Protein; Huntington Disease; Male; Mice; Mice, Inbred C57BL; Neuroglia; Neuroprotective Agents; Protein Transport; Trehalose

Emerging evidence indicates important protective roles being played by autophagy in neurodegenerative disorders through clearance of aggregate-prone or mutant proteins. In the current study, we aimed to identify autophagy inducers from Chinese medicinal herbs as a potential neuroprotective agent that enhances the clearance of mutant huntingtin and α-synuclein in PC-12 cells. Through intensive screening using the green fluorescent protein-light chain 3 (GFP-LC3) autophagy detection platform, we found that the ethanol extracts of Radix Polygalae (Yuan Zhi) were capable of inducing autophagy. Further investigation showed that among three single components derived from Radix Polygalae--i.e., polygalacic acid, senegenin and onjisaponin B--onjisaponin B was able to induce autophagy and accelerate both the removal of mutant huntingtin and A53T α-synuclein, which are highly associated with Huntington disease and Parkinson disease, respectively. Our study further demonstrated that onjisaponin B induces autophagy via the AMPK-mTOR signaling pathway. Therefore, findings in the current study provide detailed insights into the protective mechanism of a novel autophagy inducer, which is valuable for further investigation as a new candidate agent for modulating neurodegenerative disorders through the reduction of toxicity and clearance of mutant proteins in the cellular level.

Topics: alpha-Synuclein; Animals; Autophagy; Cell Line; Drugs, Chinese Herbal; Humans; Huntingtin Protein; Huntington Disease; Mutation; Nerve Tissue Proteins; Neurodegenerative Diseases; Parkinson Disease; Proteolysis; Rats; Saponins; Signal Transduction; Triterpenes

Patients exhibiting the classic manifestations of parkinsonism - tremors, rigidity, postural instability, slowed movements and, sometimes, sleep disturbances and depression - may also display severe cognitive disturbances. All of these particular motoric and behavioral symptoms may arise from Parkinson's disease [PD] per se, but they can also characterize Lewy Body dementia [LBD] or concurrent Parkinson's and Alzheimer's diseases [PD & AD]. Abnormalities of both movement and cognition are also observed in numerous other neurologic diseases, for example Huntington's Disease and the frontotemporal dementia. Distinguishing among these diseases in an individual patient is important in "personalizing" his or her mode of treatment, since an agent that is often highly effective in one of the diagnoses (e.g., L-dopa or muscarinic antagonists in PD) might be ineffective or even damaging in one of the others. That such personalization, based on genetic, biochemical, and imaging-based biomarkers, is feasible is suggested by the numerous genetic abnormalities already discovered in patients with parkinsonism, Alzheimer's disease and Huntington's disease (HD) and by the variety of regional and temporal patterns that these diseases can produce, as shown using imaging techniques.

Topics: alpha-Synuclein; Alzheimer Disease; Antiparkinson Agents; Biomarkers; Cognition; Cognition Disorders; Diagnosis, Differential; Diagnostic Imaging; Frontotemporal Dementia; Genetic Markers; Genetic Testing; Glucosylceramidase; Humans; Huntington Disease; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; Levodopa; Lewy Body Disease; Mutation; Parkinson Disease; Precision Medicine; Protein Serine-Threonine Kinases

α-Synuclein and mutant huntingtin are the major constituents of the intracellular aggregates that characterize the pathology of Parkinson's disease (PD) and Huntington's disease (HD), respectively. α-Synuclein is likely to be a major contributor to PD, since overexpression of this protein resulting from genetic triplication is sufficient to cause human forms of PD. We have previously demonstrated that wild-type α-synuclein overexpression impairs macroautophagy in mammalian cells and in transgenic mice. Overexpression of human wild-type α-synuclein in cells and Drosophila models of HD worsens the disease phenotype. Here, we examined whether α-synuclein overexpression also worsens the HD phenotype in a mammalian system using two widely used N-terminal HD mouse models (R6/1 and N171-82Q). We also tested the effects of α-synuclein deletion in the same N-terminal HD mouse models, as well as assessed the effects of α-synuclein deletion on macroautophagy in mouse brains. We show that overexpression of wild-type α-synuclein in both mouse models of HD enhances the onset of tremors and has some influence on the rate of weight loss. On the other hand, α-synuclein deletion in both HD models increases autophagosome numbers and this is associated with a delayed onset of tremors and weight loss, two of the most prominent endophenotypes of the HD-like disease in mice. We have therefore established a functional link between these two aggregate-prone proteins in mammals and provide further support for the model that wild-type α-synuclein negatively regulates autophagy even at physiological levels.

Topics: Age of Onset; alpha-Synuclein; Animals; Brain; Disease Models, Animal; Disease Progression; Female; Gene Deletion; Humans; Huntingtin Protein; Huntington Disease; Intranuclear Inclusion Bodies; Male; Mice; Mice, Transgenic; Microtubule-Associated Proteins; Nerve Tissue Proteins; Nuclear Proteins; Tremor; Weight Loss

Huntington's disease (HD) is the most common of nine inherited neurological disorders caused by expanded polyglutamine (polyQ) sequences which confer propensity to self-aggregate and toxicity to their corresponding mutant proteins. It has been postulated that polyQ expression compromises the folding capacity of the cell which might affect other misfolding-prone proteins. α-Synuclein (α-syn) is a small neural-specific protein with propensity to self-aggregate that forms Parkinson's disease (PD) Lewy bodies. Point mutations in α-syn that favor self-aggregation or α-syn gene duplications lead to familial PD, thus indicating that increased α-syn aggregation or levels are sufficient to induce neurodegeneration. Since polyQ inclusions in HD and other polyQ disorders are immunopositive for α-syn, we speculated that α-syn might be recruited as an additional mediator of polyQ toxicity. Here, we confirm in HD postmortem brains and in the R6/1 mouse model of HD the accumulation of α-syn in polyQ inclusions. By isolating the characteristic filaments formed by aggregation-prone proteins, we found that N-terminal mutant huntingtin (N-mutHtt) and α-syn form independent filamentous microaggregates in R6/1 mouse brain as well as in the inducible HD94 mouse model and that N-mutHtt expression increases the load of α-syn filaments. Accordingly, α-syn knockout results in a diminished number of N-mutHtt inclusions in transfected neurons and also in vivo in the brain of HD mice. Finally, α-syn knockout attenuates body weight loss and early motor phenotype of HD mice. This study therefore demonstrates that α-syn is a modifier of polyQ toxicity in vivo and raises the possibility that potential PD-related therapies aimed to counteract α-syn toxicity might help to slow HD.

Topics: alpha-Synuclein; Animals; Apoptosis; Atrophy; Disease Models, Animal; Female; Humans; Huntingtin Protein; Huntington Disease; Inclusion Bodies; Longevity; Male; Mice; Mice, Knockout; Motor Activity; Mutation; Neostriatum; Nerve Tissue Proteins; Neurons; Nuclear Proteins; Phenotype; Weight Loss

Several neurodegenerative disorders are characterized by the accumulation of proteinaceous inclusions in the central nervous system. These inclusions are frequently composed of a mixture of aggregation-prone proteins. Here, we used a bimolecular fluorescence complementation assay to study the initial steps of the co-aggregation of huntingtin (Htt) and α-synuclein (α-syn), two aggregation-prone proteins involved in Huntington's disease (HD) and Parkinson's disease (PD), respectively. We found that Htt (exon 1) oligomerized with α-syn and sequestered it in the cytosol. In turn, α-syn increased the number of cells displaying aggregates, decreased the number of aggregates per cell and increased the average size of the aggregates. Our results support the idea that co-aggregation of aggregation-prone proteins can contribute to the histopathology of neurodegenerative disorders.

Topics: alpha-Synuclein; Cell Line, Tumor; Cytosol; Exons; Humans; Huntingtin Protein; Huntington Disease; Microscopy, Fluorescence; Nerve Tissue Proteins; Nuclear Proteins; Parkinson Disease

Huntington and Parkinson diseases (HD and PD) are two major neurodegenerative disorders pathologically characterized by the accumulation of the aggregate-prone proteins mutant huntingtin (in HD) and α-synuclein (in PD). Mutant huntingtin is an autophagy substrate and autophagy modulators affect HD pathology both in vitro and in vivo. In vitro, α-synuclein levels are able to modulate autophagy: α-synuclein overexpression inhibits autophagy, whereas downregulation promotes autophagy. Here, we review our recent studies showing that α-synuclein levels modulate mutant huntingtin toxicity in mouse models. This phenotypic modification is accompanied by the in vivo modulation of autophagosome numbers in mouse brains from both control and HD mice expressing different levels of α-synuclein.

Topics: alpha-Synuclein; Animals; Autophagy; Disease Models, Animal; Drosophila melanogaster; Humans; Huntington Disease; Mice; Microtubule-Associated Proteins; Mutant Proteins; Phagosomes

Lysosomes are involved in degrading and recycling cellular ingredients, and their disruption with age may contribute to amyloidogenesis, paired helical filaments (PHFs), and α-synuclein and mutant huntingtin aggregation. Lysosomal cathepsins are upregulated by accumulating proteins and more so by the modulator Z-Phe-Ala-diazomethylketone (PADK). Such positive modulators of the lysosomal system have been studied in the well-characterized hippocampal slice model of protein accumulation that exhibits the pathogenic cascade of tau aggregation, tubulin breakdown, microtubule destabilization, transport failure, and synaptic decline. Active cathepsins were upregulated by PADK; Rab proteins were modified as well, indicating enhanced trafficking, whereas lysosome-associated membrane protein and proteasome markers were unchanged. Lysosomal modulation reduced the pre-existing PHF deposits, restored tubulin structure and transport, and recovered synaptic components. Further proof-of-principle studies used Alzheimer disease mouse models. It was recently reported that systemic PADK administration caused dramatic increases in cathepsin B protein and activity levels, whereas neprilysin, insulin-degrading enzyme, α-secretase, and β-secretase were unaffected by PADK. In the transgenic models, PADK treatment resulted in clearance of intracellular amyloid beta (Aβ) peptide and concomitant reduction of extracellular deposits. Production of the less pathogenic Aβ(1-38) peptide corresponded with decreased levels of Aβ(1-42), supporting the lysosome's antiamyloidogenic role through intracellular truncation. Amelioration of synaptic and behavioral deficits also indicates a neuroprotective function of the lysosomal system, identifying lysosomal modulation as an avenue for disease-modifying therapies. From the in vitro and in vivo findings, unique lysosomal modulators represent a minimally invasive, pharmacologically controlled strategy against protein accumulation disorders to enhance protein clearance, promote synaptic integrity, and slow the progression of dementia.

Topics: Aging; alpha-Synuclein; Alzheimer Disease; Animals; Cathepsins; Dementia; Diazomethane; Humans; Huntingtin Protein; Huntington Disease; Ketones; Lysosomes; Mice; Mice, Transgenic; Nerve Tissue Proteins; Nuclear Proteins; Phagocytosis; Protease Inhibitors; Proteins; rab GTP-Binding Proteins; Synapses; tau Proteins

The pathologies of major neurodegenerative diseases including Parkinson disease and Alzheimer disease have been well known for decades. More recently, advances in molecular genetics have suggested important mechanistic links between the pathology of these disorders and pathogenesis of neuronal dysfunction and death. Numerous animal models have been produced based on the new information emerging from human genetic studies. As a complement to traditional mouse models, a number of investigators have modeled neurodegenerative diseases in simple model organisms ranging from yeast to Drosophila. These simple genetic models often display remarkable pathological similarities to their cognate human disorders, and genetic and biochemical studies have yielded important insights into the pathogenesis of the human disorders. Use of these tractable simple models may become even more important as large amounts of genetic data emerge from genome-wide association studies in Alzheimer disease, Parkinson disease, and other neurodegenerative disorders.

Topics: alpha-Synuclein; Amyloid beta-Peptides; Animals; Disease Models, Animal; Drosophila melanogaster; Genome-Wide Association Study; Humans; Huntington Disease; Models, Biological; Models, Genetic; Neurodegenerative Diseases; Neurons; Phosphorylation

Animal models of neurodegenerative disease are excellent tools for studying pathogenesis and therapies including cellular transplantation. In this chapter, we describe different models of Huntington's disease and Parkinson's disease, stereotactic surgery (used in creation of lesion models and transplantation) and finally transplantation studies in these models.

Topics: alpha-Synuclein; Animals; Caenorhabditis elegans; Cell- and Tissue-Based Therapy; Disease Models, Animal; Drosophila; Humans; Huntington Disease; Mice; Mice, Transgenic; Parkinson Disease; Stem Cell Transplantation; Zebrafish

Coenzyme Q(10) (CoQ(10)) and creatine are promising agents for neuroprotection in neurodegenerative diseases via their effects on improving mitochondrial function and cellular bioenergetics and their properties as antioxidants. We examined whether a combination of CoQ(10) with creatine can exert additive neuroprotective effects in a MPTP mouse model of Parkinson's disease, a 3-NP rat model of Huntington's disease (HD) and the R6/2 transgenic mouse model of HD. The combination of the two agents produced additive neuroprotective effects against dopamine depletion in the striatum and loss of tyrosine hydroxylase neurons in the substantia nigra pars compacta (SNpc) following chronic subcutaneous administration of MPTP. The combination treatment resulted in significant reduction in lipid peroxidation and pathologic alpha-synuclein accumulation in the SNpc neurons of the MPTP-treated mice. We also observed additive neuroprotective effects in reducing striatal lesion volumes produced by chronic subcutaneous administration of 3-NP to rats. The combination treatment showed significant effects on blocking 3-NP-induced impairment of glutathione homeostasis and reducing lipid peroxidation and DNA oxidative damage in the striatum. Lastly, the combination of CoQ(10) and creatine produced additive neuroprotective effects on improving motor performance and extending survival in the transgenic R6/2 HD mice. These findings suggest that combination therapy using CoQ(10) and creatine may be useful in the treatment of neurodegenerative diseases such as Parkinson's disease and HD.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; 8-Hydroxy-2'-Deoxyguanosine; alpha-Synuclein; Analysis of Variance; Animals; Chromatography, High Pressure Liquid; Creatine; Deoxyguanosine; Disease Models, Animal; Dopamine; Drug Therapy, Combination; Glutathione; Glutathione Disulfide; Huntington Disease; Lipid Peroxidation; Male; Malondialdehyde; Mice; Mice, Inbred C57BL; Neuroprotective Agents; Nitro Compounds; Parkinson Disease; Propionates; Rats; Rats, Inbred Lew; Tyrosine 3-Monooxygenase; Ubiquinone

Many diverse human diseases are associated with protein aggregation in ordered fibrillar structures called amyloid. Amyloid formation may mediate aberrant protein interactions that culminate in neurodegeneration in Alzheimer, Huntington, and Parkinson diseases and in prion encephalopathies. Studies of protein aggregation in the brain are hampered by limitations in imaging techniques and often require invasive methods that can only be performed postmortem. Here we describe transgenic mice in which aggregation-prone proteins that cause Huntington and Parkinson disease are expressed in the ocular lens. Expression of a mutant huntingtin fragment or alpha-synuclein in the lens leads to protein aggregation and cataract formation, which can be monitored in real time by noninvasive, highly sensitive optical techniques. Expression of a mutant huntingtin fragment in mice lacking the major lens chaperone, alphaB-crystallin, markedly accelerated the onset and severity of aggregation, demonstrating that the endogenous chaperone activity of alphaB-crystallin suppresses aggregation in vivo. These novel mouse models will facilitate the characterization of protein aggregation in vivo and are being used in efficient and economical screens for chemical and genetic modifiers of disease-relevant protein aggregation.

Topics: alpha-Crystallin B Chain; alpha-Synuclein; Alzheimer Disease; Animals; Cataract; Disease Models, Animal; Gene Expression; Huntingtin Protein; Huntington Disease; Lens, Crystalline; Mice; Mice, Transgenic; Mutation; Nerve Tissue Proteins; Nuclear Proteins; Parkinson Disease

Trehalose, a disaccharide present in many non-mammalian species, protects cells against various environmental stresses. Whereas some of the protective effects may be explained by its chemical chaperone properties, its actions are largely unknown. Here we report a novel function of trehalose as an mTOR-independent autophagy activator. Trehalose-induced autophagy enhanced the clearance of autophagy substrates like mutant huntingtin and the A30P and A53T mutants of alpha-synuclein, associated with Huntington disease (HD) and Parkinson disease (PD), respectively. Furthermore, trehalose and mTOR inhibition by rapamycin together exerted an additive effect on the clearance of these aggregate-prone proteins because of increased autophagic activity. By inducing autophagy, we showed that trehalose also protects cells against subsequent pro-apoptotic insults via the mitochondrial pathway. The dual protective properties of trehalose (as an inducer of autophagy and chemical chaperone) and the combinatorial strategy with rapamycin may be relevant to the treatment of HD and related diseases, where the mutant proteins are autophagy substrates.

Topics: alpha-Synuclein; Animals; Antibiotics, Antineoplastic; Autophagy; Chlorocebus aethiops; COS Cells; HeLa Cells; Humans; Huntingtin Protein; Huntington Disease; Mice; Molecular Chaperones; Mutation; Nerve Tissue Proteins; Nuclear Proteins; Parkinson Disease; Protein Kinases; Sirolimus; TOR Serine-Threonine Kinases; Trehalose

Misfolded proteins accumulate in many neurodegenerative diseases, including huntingtin in Huntington's disease and alpha-synuclein in Parkinson's disease. The disease-causing proteins can take various conformations and are prone to aggregate and form larger cytoplasmic or nuclear inclusions. One approach to the development of therapeutic intervention for these diseases has been to identify chemical compounds that reduce the size or number of inclusions. We have, however, identified a compound that promotes inclusion formation in cellular models of both Huntington's disease and Parkinson's disease. Of particular interest, this compound prevents huntingtin-mediated proteasome dysfunction and reduces alpha-synuclein-mediated toxicity. These results demonstrate that compounds that increase inclusion formation may actually lessen cellular pathology in both Huntington's and Parkinson's diseases, suggesting a therapeutic approach for neurodegenerative diseases caused by protein misfolding.

Topics: alpha-Synuclein; Amino Acid Sequence; Animals; Base Sequence; Cell Line; CHO Cells; Cricetinae; DNA, Recombinant; Genes, Reporter; Green Fluorescent Proteins; Humans; Huntingtin Protein; Huntington Disease; In Vitro Techniques; Inclusion Bodies; Nerve Tissue Proteins; Nuclear Proteins; Parkinson Disease; Piperazines; Proteasome Endopeptidase Complex; Protein Folding; Quinolines; Recombinant Fusion Proteins

Topics: alpha-Synuclein; Humans; Huntingtin Protein; Huntington Disease; Nerve Tissue Proteins; Neuroprotective Agents; Nitroquinolines; Nuclear Proteins; Parkinson Disease; Piperazines; Protein Folding; Ubiquitin-Protein Ligases

Topics: alpha-Synuclein; Animals; Disease Models, Animal; Genetic Therapy; Humans; Huntingtin Protein; Huntington Disease; Mutation; Nerve Tissue Proteins; Neurosciences; Nuclear Proteins; Parkinson Disease; Primates; Rats; Time Factors; Transgenes

The huntingtin exon 1 proteins with a polyglutamine repeat in the pathological range (51 or 83 glutamines), but not with a polyglutamine tract in the normal range (20 glutamines), form aggresome-like perinuclear inclusions in human 293 Tet-Off cells. These structures contain aggregated, ubiquitinated huntingtin exon 1 protein with a characteristic fibrillar morphology. Inclusion bodies with truncated huntingtin protein are formed at centrosomes and are surrounded by vimentin filaments. Inhibition of proteasome activity resulted in a twofold increase in the amount of ubiquitinated, SDS-resistant aggregates, indicating that inclusion bodies accumulate when the capacity of the ubiquitin-proteasome system to degrade aggregation-prone huntingtin protein is exhausted. Immunofluorescence and electron microscopy with immunogold labeling revealed that the 20S, 19S, and 11S subunits of the 26S proteasome, the molecular chaperones BiP/GRP78, Hsp70, and Hsp40, as well as the RNA-binding protein TIA-1, the potential chaperone 14-3-3, and alpha-synuclein colocalize with the perinuclear inclusions. In 293 Tet-Off cells, inclusion body formation also resulted in cell toxicity and dramatic ultrastructural changes such as indentations and disruption of the nuclear envelope. Concentration of mitochondria around the inclusions and cytoplasmic vacuolation were also observed. Together these findings support the hypothesis that the ATP-dependent ubiquitin-proteasome system is a potential target for therapeutic interventions in glutamine repeat disorders.

Topics: 14-3-3 Proteins; Acetylcysteine; alpha-Synuclein; Carrier Proteins; Cell Line; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Endoplasmic Reticulum Chaperone BiP; Exons; Heat-Shock Proteins; Humans; Huntingtin Protein; Huntington Disease; Immunoblotting; Inclusion Bodies; Membrane Proteins; Microscopy, Fluorescence; Models, Biological; Molecular Chaperones; Multienzyme Complexes; Mutation; Nerve Tissue Proteins; Nuclear Proteins; Peptide Fragments; Poly(A)-Binding Proteins; Proteasome Endopeptidase Complex; Proteins; Recombinant Fusion Proteins; RNA-Binding Proteins; Synucleins; T-Cell Intracellular Antigen-1; Transgenes; Tyrosine 3-Monooxygenase; Vimentin

The first gene to be linked to Parkinson's disease encodes the neuronal protein alpha-synuclein. Recent mouse and Drosophila models of Parkinson's disease support a central role for the process of alpha-synuclein fibrillization in pathogenesis. However, some evidence indicates that the fibril itself may not be the pathogenic species. Our own biophysical studies suggest that a structured fibrillization intermediate or an alternatively assembled oligomer may be responsible for neuronal death. This speculation can now be experimentally tested in the animal models. Such experiments will have implications for the development of new therapies for Parkinson's disease and related neurodegenerative diseases.

Topics: Age of Onset; alpha-Synuclein; Animals; Disease Models, Animal; Genetic Predisposition to Disease; Humans; Huntington Disease; Ligases; Mice; Mice, Knockout; Mice, Transgenic; Nerve Tissue Proteins; Parkinson Disease; Proteins; Synucleins; Thiolester Hydrolases; Ubiquitin Thiolesterase; Ubiquitin-Protein Ligases

Polyglutamine expansions in proteins are implicated in at least eight inherited neurodegenerative disorders, including Huntington's disease. These mutant proteins can form aggregates within the nucleus and processes of neurons possibly due to misfolding of the proteins. Polyglutamine aggregates are ubiquitinated and sequester molecular chaperone proteins and proteasome components. To investigate other protein components of polyglutamine aggregates, cerebral cortex and striata from patients with Huntington's disease and full-length cDNA transgenic mouse models for this disease were examined immunohistochemically for alpha-synuclein reactivity. Our findings demonstrate that alpha-synuclein can be used as a marker for huntingtin polyglutamine aggregates in both human and mice. Moreover in the HD transgenic mice, the intensity of immunoreactivity increases with age. The significance of recruitment of alpha-synuclein into huntingtin aggregates and its translocation away from the synapses remains to be determined. We propose that aberrant interaction of mutant huntingtin with other proteins, including alpha-synuclein, may influence disease progression.

Topics: alpha-Synuclein; Amino Acid Motifs; Animals; Cerebral Cortex; Corpus Striatum; Disease Models, Animal; Female; Humans; Huntingtin Protein; Huntington Disease; Immunohistochemistry; Mice; Mice, Transgenic; Nerve Tissue Proteins; Nuclear Proteins; Peptides; Phosphoproteins; Protein Folding; Rabbits; Synucleins