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Ageing Res Rev,
2014]
Parkinson disease (PD; MIM 168600) is the second most common progressive neurodegenerative disorder characterized by a variety of motor and non-motor features. To date, at least 20 loci and 15 disease-causing genes for parkinsonism have been identified. Among them, the -synuclein (SNCA) gene was associated with PARK1/PARK4. Point mutations, duplications and triplications in the SNCA gene cause a rare dominant form of PD in familial and sporadic PD cases. The -synuclein protein, a member of the synuclein family, is abundantly expressed in the brain. The protein is the major component of Lewy bodies and Lewy neurites in dopaminergic neurons in PD. Further understanding of its role in the pathogenesis of PD through various genetic techniques and animal models will likely provide new insights into our understanding, therapy and prevention of PD.
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Trends Pharmacol Sci,
2012]
Parkinson's disease (PD) is caused by the progressive degeneration of dopaminergic neurons in the substantia nigra. Although the etiology for most PD remains elusive, the identification of specific genetic defects in familial cases of PD and the signaling pathways governed by these genes has provided tremendous insight into PD pathogenesis. Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are frequently found in familial and sporadic PD. Although current knowledge regarding the regulatory mechanisms of LRRK2 activation is limited, it is becoming increasingly evident that aberrant kinase activity of the pathologic mutants of LRRK2 is associated with neurodegeneration, suggesting that the kinase activity of LRRK2 is a potential therapeutic target. In addition, LRRK2 inhibitors might provide valuable tools to understand the pathophysiological and physiological roles of LRRK2 as well as the etiology of PD. We discuss here the potential and feasibility of targeting LRRK2 as a therapeutic strategy for PD.
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Front Genet,
2017]
Parkinson's disease (PD) is a neurodegenerative disorder with symptoms that progressively worsen with age. Pathologically, PD is characterized by the aggregation of -synuclein in cells of the substantia nigra in the brain and loss of dopaminergic neurons. This pathology is associated with impaired movement and reduced cognitive function. The etiology of PD can be attributed to a combination of environmental and genetic factors. A popular animal model, the nematode roundworm Caenorhabditis elegans, has been frequently used to study the role of genetic and environmental factors in the molecular pathology and behavioral phenotypes associated with PD. The current review summarizes cellular markers and behavioral phenotypes in transgenic and toxin-induced PD models of C. elegans.
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Mol Interv,
2008]
It has been over forty years since dopamine neuron degeneration in the substantia nigra and Lewy body formation within surviving cells were described as the pathological hallmarks of Parkinson''s disease (PD). Although research in the intervening decades particularly in the last twenty-five years has yielded a variety of robust animal models and invaluable mechanistic insights into PD-associated neuronal dysfunction and cell death, therapeutic agents have not been forthcoming to alter the course of PD. Recently, the screening of experimental therapeutics for PD has been pursued through the use of genetically tractable models, such as the nematode Caenorhabditis elegans. This simple worm remarkably recapitulates the basic cellular and molecular pathways associated with PD, is amenable to facile genetic methods, and through the use of high-throughput screening technologies, provides powerful new opportunities for the in vivo identification of therapeutic targets. In this review we briefly describe the utility that the C. elegans model system may have for PD drug discovery.
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Brain Sci,
2019]
Parkinson's Disease (PD) is the second-most common neurodegenerative disease in the world, yet the fundamental and underlying causes of the disease are largely unknown, and treatments remain sparse and impotent. Several biological systems have been employed to model the disease but the nematode roundworm <i>Caenorhabditis elegans (C. elegans)</i> shows unique promise among these to disinter the elusive factors that may prevent, halt, and/or reverse PD phenotypes. Some of the most salient of these <i>C. elegans</i> models of PD are those that position the misfolding-prone protein alpha-synuclein (-syn), a hallmark pathological component of PD, as the primary target for scientific interrogation. By transgenic expression of human -syn in different tissues, including dopamine neurons and muscle cells, the primary cellular phenotypes of PD in humans have been recapitulated in these <i>C. elegans</i> models and have already uncovered multifarious genetic factors and chemical compounds that attenuate dopaminergic neurodegeneration. This review describes the paramount discoveries obtained through the application of different -syn models of PD in <i>C. elegans</i> and highlights their established utility and respective promise to successfully uncover new conserved genetic modifiers, functional mechanisms, therapeutic targets and molecular leads for PD with the potential to translate to humans.
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Mov Disord,
2013]
Impairment of autophagy-lysosomal pathways (ALPs) is increasingly regarded as a major pathogenic event in neurodegenerative diseases, including Parkinson's disease (PD). ALP alterations are observed in sporadic PD brains and in toxic and genetic rodent models of PD-related neurodegeneration. In addition, PD-linked mutations and post-translational modifications of -synuclein impair its own lysosomal-mediated degradation, thereby contributing to its accumulation and aggregation. Furthermore, other PD-related genes, such as leucine-rich repeat kinase-2 (LRRK2), parkin, and phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1), have been mechanistically linked to alterations in ALPs. Conversely, mutations in lysosomal-related genes, such as glucocerebrosidase (GBA) and lysosomal type 5 P-type ATPase (ATP13A2), have been linked to PD. New data offer mechanistic molecular evidence for such a connection, unraveling a causal link between lysosomal impairment, -synuclein accumulation, and neurotoxicity. First, PD-related GBA deficiency/mutations initiate a positive feedback loop in which reduced lysosomal function leads to -synuclein accumulation, which, in turn, further decreases lysosomal GBA activity by impairing the trafficking of GBA from the endoplasmic reticulum-Golgi to lysosomes, leading to neurodegeneration. Second, PD-related mutations/deficiency in the ATP13A2 gene lead to a general lysosomal impairment characterized by lysosomal membrane instability, impaired lysosomal acidification, decreased processing of lysosomal enzymes, reduced degradation of lysosomal substrates, and diminished clearance of autophagosomes, collectively contributing to -synuclein accumulation and cell death. According to these new findings, primary lysosomal defects could potentially account for Lewy body formation and neurodegeneration in PD, laying the groundwork for the prospective development of new neuroprotective/disease-modifying therapeutic strategies aimed at restoring lysosomal levels and function.
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Prog Neurobiol,
2010]
Parkinson's disease (PD) was one of the first neurological disorders to have aspects of the disease modeled faithfully in non-human animal species. A key feature of the disease is a diminished control over voluntary movement and progressive depletion of brain dopamine (DA) levels that stems from the large-scale loss of DA-producing neurons. Despite their inherent limitations, rodent and non-human primate models of PD have helped unravel several aspects of PD pathogenesis. Thus, we now have neurotransmitter replacement therapy for PD, and a number of neuroprotective compounds that can be assessed in clinical trials. However, no treatment is currently available that can halt or retard the progressive loss of DA neurons, which underlies PD pathology. Moreover, no therapies can permanently alleviate the clinical features of the disease. The lack of a cure or long-term effective treatment is paralled by our incomplete understanding of the underlying pathomechanisms of the disease. A range of robust, flexible, and complementary animal models will be an invaluable tool with which to unravel the pathogenesis of PD. Here we review the most important contributions made by non-mammalian model organisms. These include zebrafish (Danio rerio), flies (Drosophila melanogaster), anurans (frogs and toads) and nematodes (Caenorhabditis elegans). While it is not anticipated that they will replace rodent and primate-based ones, they offer convenient systems with which to explore the relative contribution made by genetic and environmental factors to PD pathology. In addition, they offer an economic and rapid alternative for testing compounds that target PD. Most importantly, the combined use of these models allow for ongoing research to uncover the basic mechanisms underlying PD pathogenesis.
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Dev Dyn,
2010]
Parkinson's disease (PD) is an age-related movement disorder resulting, in part, from selective loss of dopaminergic neurons. Both invertebrate and mammalian models have been developed to study the cellular mechanisms altered during disease progression; nevertheless there are limitations within each model. Mammalian models remain invaluable in studying PD, but are expensive and time consuming. Here, we review genetic and environmental factors associated with PD, and describe how the nematode roundworm, Caenorhabditis elegans, has been used as a model organism for studying various aspects of this neurodegenerative disease. Both genetic and chemical screens have been conducted in C. elegans to identify molecular pathways, proteins, and small molecules that can impact PD pathology. Lastly, we highlight future areas of investigation, in the context of emerging fields in biology, where the nematode can be exploited to provide mechanistic insights and potential strategies to accelerate the path toward possible therapeutic intervention for PD.
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CNS Neurol Disord Drug Targets,
2012]
Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor and non-motor symptoms and the selective loss of dopaminergic neurons. The etiology of idiopathic PD is likely a combination of genetic and environmental factors. Despite findings from mammalian studies that have provided significant insight into the disorder, the molecular mechanisms underlying its pathophysiology are still poorly understood. The nematode Caenorhabditis elegans (C. elegans) is a powerful system for genetic analysis. Considering C. elegans short lifespan, fully sequenced genome, high genetic and neurobiochemical conservation with humans, as well as the availability of facile genetic tools, the nematode represents a highly efficient and effective model system to explore the molecular basis of PD. In this review we describe the utility of C. elegans for PD research, and the opportunity the model system presents to identify therapeutic targets.
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Curr Opin Genet Dev,
2017]
The nematode Caenorhabditis elegans possesses a wealth of opportunities to explore mechanisms which regulate metazoan complexity, basic cellular biology, and neuronal system attributes. Together, these provide a basis for tenable understanding of neurodegenerative disorders such as Parkinson disease (PD) through functional genomic analysis and pharmacological manipulation for the discovery of previously unknown genetic and environmental risk factors. The application of C. elegans has proven prescient in terms of the elucidation of functional effectors of cellular mechanisms underlying PD that translate to mammals. The current state of PD research using C. elegans encompasses defining obscure combinatorial interactions between genes or between genes and the environment, and continues to provide opportunities for the discovery of new therapeutic targets and disease-modifying drugs.