Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Parkinson's disease (PD) is the most common neurodegenerative movement disorder. The major motor disabilities of PD are associated with the extensive loss of dopaminergic neurons in the substantia nigra pars compacta. The physiological changes and biochemical pathways involved in the selective demise of these neurons are still unclear. Recent studies have demonstrated that alterations or reductions in ubiquitin-mediated proteasome function can be causal of at least some forms of parkinsonism, and multiple lines of evidence suggest that this mechanism of protein degradation may play an important role in the etiology of PD.
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PMID:Are ubiquitination pathways central to Parkinson's disease? 1285 88

Many hereditary and sporadic neurodegenerative disorders are characterized by the accumulation of aberrant proteins. In sporadic Parkinson's disease, representing the most prevalent movement disorder, oxidative and nitrosative stress are believed to contribute to disease pathogenesis, but the exact molecular basis for protein aggregation remains unclear. In the case of autosomal recessive-juvenile Parkinsonism, mutation in the E3 ubiquitin ligase protein parkin is linked to death of dopaminergic neurons. Here we show both in vitro and in vivo that nitrosative stress leads to S-nitrosylation of wild-type parkin and, initially, to a dramatic increase followed by a decrease in the E3 ligase-ubiquitin-proteasome degradative pathway. The initial increase in parkin's E3 ubiquitin ligase activity leads to autoubiquitination of parkin and subsequent inhibition of its activity, which would impair ubiquitination and clearance of parkin substrates. These findings may thus provide a molecular link between free radical toxicity and protein accumulation in sporadic Parkinson's disease.
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PMID:Nitrosative stress linked to sporadic Parkinson's disease: S-nitrosylation of parkin regulates its E3 ubiquitin ligase activity. 1525 5

Parkinson disease (PD), the most common neurodegenerative movement disorder, is characterized by an extensive and progressive loss of dopaminergic neurons in the substantia nigra pars compacta. One of the pathological hallmarks of PD is the presence of Lewy bodies, intracellular inclusions of aggregated alpha-synuclein. Although the cause and pathogenesis of selective loss of dopamine neurons and the accumulation of alpha-synuclein in PD remain elusive, growing lines of evidence from environmental risk factors and early-onset genetics point to a convergence between energy metabolism and the disposal of damaged proteins in the development of PD. These findings suggest that impairments in mitochondrial and ubiquitin-proteasome system function can significantly contribute to the pathogenesis of PD. This review will summarize recent insights gained from genetic and environmental studies of PD that underscore this association.
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PMID:Molecular pathogenesis of Parkinson disease. 1576 99

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder that results primarily from the death of dopaminergic neurons in the substantia nigra. Although the etiology of PD is incompletely understood, the recent discovery of genes associated with rare monogenic forms of the disease, together with earlier studies and new experimental animal models, has provided important and novel insight into the molecular pathways involved in disease pathogenesis. Increasing evidence indicates that deficits in mitochondrial function, oxidative and nitrosative stress, the accumulation of aberrant or misfolded proteins, and ubiquitin-proteasome system dysfunction may represent the principal molecular pathways or events that commonly underlie the pathogenesis of sporadic and familial forms of PD .
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PMID:Molecular pathophysiology of Parkinson's disease. 1602 90

Parkinson's disease (PD) is a neurodegenerative movement disorder characterized by selective loss of dopaminergic neurons and the presence of Lewy bodies. Alpha-synuclein is a major component of Lewy bodies in sporadic PD, and mutations in alpha-synuclein cause autosomal-dominant hereditary PD. Here, we generated A53T mutant alpha-synuclein-inducible PC12 cell lines using the Tet-off regulatory system. Inducing expression of A53T alpha-synuclein in differentiated PC12 cells decreased proteasome activity, increased the intracellular ROS level and caused up to approximately 40% cell death, which was accompanied by mitochondrial cytochrome C release and elevation of caspase-9 and -3 activities. Cell death was partially blocked by cyclosporine A [an inhibitor of the mitochondrial permeability transition (MPT) process], z-VAD (a pan-caspase inhibitor) and inhibitors of caspase-9 and -3 but not by a caspase-8 inhibitor. Furthermore, induction of A53T alpha-synuclein increased endoplasmic reticulum (ER) stress and elevated caspase-12 activity. RNA interference to knock down caspase-12 levels or salubrinal (an ER stress inhibitor) partially protected against cell death and further reduced A53T toxicity after treatment with z-VAD. Our results indicate that both ER stress and mitochondrial dysfunction contribute to A53T alpha-synuclein-induced cell death. This study sheds light into the pathogenesis of alpha-synuclein cellular toxicity in PD and provides a cell model for screening PD therapeutic agents.
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PMID:Endoplasmic reticulum stress and mitochondrial cell death pathways mediate A53T mutant alpha-synuclein-induced toxicity. 1623 41

1. Parkinson's disease (PD) is considered to be an aging-related neurodegeneration of catecholamine (CA) systems [typically A9 dopamine (DA) neurons in the substantia nigra and A6 noradrenaline (NA) neurons in the locus coeruleus]. The main symptom is movement disorder caused by a DA deficiency at the nerve terminals of fibers that project from the substantia nigra to the striatum. Most PD is sporadic (sPD) without any hereditary history. sPD is speculated to be caused by some exogenous or endogenous substances that are neurotoxic toward CA neurons, which toxicity leads to mitochondrial dysfunction and subsequent oxidative stress resulting in the programmed cell death (apoptosis or autophagy) of DA neurons. 2. Recent studies on the causative genes of rare familial PD (fPD) cases, such as alpha-synuclein and parkin, suggest that dysfunction of the ubiquitin-proteasome system (UPS) and the resultant accumulation of misfolded proteins and endoplasmic reticulum stress may cause the death of DA neurons. 3. Activated microglia, which accompany an inflammatory process, are present in the nigro-striatum of the PD brain; and they produce protective or toxic substances, such as cytokines, neurotrophins, and reactive oxygen or nitrogen species. These activated microglia may be neuroprotective at first in the initial stage, and later may become neurotoxic owing to toxic change to promote the progression toward the death of CA neurons.4. All of these accumulating evidences on sPD and fPD points to a hypothesis that multiple primary causes of PD may be ultimately linked to a final common signal-transduction pathway leading to programmed cell death, i.e., apoptosis or autophagy, of the CA neurons.
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PMID:Cellular and molecular mechanisms of Parkinson's disease: neurotoxins, causative genes, and inflammatory cytokines. 1682 25

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder characterized by selective loss of dopaminergic neurons and the presence of Lewy bodies. Alpha-synuclein is a major component of Lewy bodies in sporadic PD, and genetic alterations in alpha-synuclein cause autosomal-dominant hereditary PD. The pathogenesis of PD remains incompletely understood, but it appears to involve both genetic susceptibility and environmental factors. Here we investigated the effect of alpha-synuclein expression on cell susceptibility to proteasome inhibition, oxidative and nitrative stresses by using a PC 12-Tet-off regulatory system. We found that inducible expression of A30P or A53T mutant alpha-synuclein decreased the proteasome activity, increased intracellular ROS levels, and enhanced lactacystin- and H2O2-induced cell death. Furthermore, 3-nitrotyrosine levels increased in cells expressing alpha-synuclein, and further increased after Sin-1 (a NO donor) treatment compared with untreated or treated non-induced cells. Expression of alpha-synuclein (mutant more than wild type) significantly enhances Sin-1 toxicity. These results indicate that genetic mutations in alpha-synuclein may increase neuronal vulnerability to cellular stress in aging and PD pathogenesis.
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PMID:Parkinson's disease genetic mutations increase cell susceptibility to stress: mutant alpha-synuclein enhances H2O2- and Sin-1-induced cell death. 1697 43

Parkinson's disease (PD) is the most common neurodegenerative movement disorder. Although a subject of intense research, the etiology of PD remains poorly understood. Recently, several lines of evidence have implicated an intimate link between aberrations in the ubiquitin proteasome system (UPS) and PD pathogenesis. Derangements of the UPS, which normally functions as a type of protein degradation machinery, lead to alterations in protein homeostasis that could conceivably promote the toxic accumulation of proteins detrimental to neuronal survival. Not surprisingly, various cellular and animal models of PD that are based on direct disruption of UPS function reproduce the most prominent features of PD. Although persuasive, new developments in the past few years have in fact raised serious questions about the link between the UPS and PD. Here I review current thoughts and controversies about their relationship and discuss whether strategies aimed at mitigating UPS dysfunction could represent rational ways to intervene in the disease. Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com).
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PMID:Role of the ubiquitin proteasome system in Parkinson's disease. 1804 37

Parkinson's disease (PD) is the most common neurodegenerative movement disorder. Although a subject of intense research, the etiology of PD remains poorly understood. Over the last decade, the ubiquitin-proteasome system (UPS) has emerged as a compelling player in PD pathogenesis. Disruption of the UPS, which normally identifies and degrades intracellular proteins, is thought to promote the toxic accumulation of proteins detrimental to neuronal survival, thereby contributing to their demise. Support for this came from a broad range of studies, including genetics, gene profiling and post-mortem analysis, as well as in vitro and in vivo modeling. Notably, various cellular and animal models of PD based on direct disruption of UPS function reproduce the salient features of PD. However, several gaps remain in our current knowledge regarding the precise role of UPS dysfunction in the pathogenesis of the disease. Current thoughts regarding their relationship are reviewed here and some major unresolved questions, the clarification of which would considerably advance our understanding of the implicated role of the UPS in PD pathogenesis, are discussed.
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PMID:Ubiquitin-proteasome system dysfunction in Parkinson's disease: current evidence and controversies. 1806 15

Increased iron levels and iron-mediated oxidative stress play an important role in the pathogenesis of many neurodegenerative diseases. The finding that mutations in the ferritin light polypeptide (FTL) gene cause a neurodegenerative disease known as neuroferritinopathy or hereditary ferritinopathy (HF) provided a direct connection between abnormal brain iron storage and neurodegeneration. HF is characterized by a severe movement disorder and by the presence of nuclear and cytoplasmic ferritin inclusion bodies in glia and neurons throughout the CNS and in tissues of multiple organ systems. Here we report that the expression in transgenic mice of a human FTL cDNA carrying a thymidine and cytidine insertion at position 498 (FTL498-499InsTC) leads to the formation of nuclear and cytoplasmic ferritin inclusion bodies. As in HF, ferritin inclusions are seen in glia and neurons throughout the CNS as well as in cells of other organ systems. Our studies show histological, immunohistochemical, and biochemical similarities between ferritin inclusion bodies found in transgenic mice and in individuals with HF. Expression of the transgene in mice leads to a significant decrease in motor performance and a shorter life span, formation of ferritin inclusion bodies, misregulation of iron metabolism, accumulation of ubiquitinated proteins, and incorporation of elements of the proteasome into inclusions. This new transgenic mouse represents a relevant model of HF in which to study the pathways that lead to neurodegeneration in HF, to evaluate the role of iron mismanagement in neurodegenerative disorders, and to evaluate potential therapies for HF and related neurodegenerative diseases.
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PMID:Expression of a mutant form of the ferritin light chain gene induces neurodegeneration and iron overload in transgenic mice. 1817 23


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