Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Lewy bodies (LBs), which are the hallmark pathologic features of Parkinson's disease and of dementia with LBs, have several morphologic and molecular similarities to aggresomes. Whether such cytoplasmic inclusions contribute to neuronal death or protect cells from the toxic effects of misfolded proteins remains controversial. In this report, the role of aggresomes in cell viability was addressed in the context of over-expressing alpha-synuclein and its interacting partner synphilin-1 using engineered 293T cells. Inhibition of proteasome activity elicited the formation of juxtanuclear aggregates with characteristics of aggresomes including immunoreactivity for vimentin, gamma-tubulin, ubiquitin, proteasome subunit, and hsp70. As expected from the properties of aggresomes, the microtubule disrupting agents, vinblastin and nocodazole, markedly prevented the formation of these inclusions. Similar to LBs, the phosphorylated form of alpha-synuclein co-localized in these synphilin-1-containing aggresomes. Although the caspase inhibitor z-VAD-fmk significantly reduced the number of apoptotic cells, it had no impact on the percentage of aggresome-positive cells. Finally, quantitative analysis revealed aggresomes in 60% of nonapoptotic cells but only in 10% of apoptotic cells. Additionally, alpha-synuclein-induced apoptosis was not coupled with increased prevalence of aggresome-bearing cells. Taken together, these observations indicate a disconnection between aggresome formation and apoptosis, and support a protective role for these inclusions from the toxicity associated with the combined over-expression of alpha-synuclein and synphilin-1.
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PMID:Aggresomes formed by alpha-synuclein and synphilin-1 are cytoprotective. 1462 98

Inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia (IBMPFD) is a dominant progressive disorder that maps to chromosome 9p21.1-p12. We investigated 13 families with IBMPFD linked to chromosome 9 using a candidate-gene approach. We found six missense mutations in the gene encoding valosin-containing protein (VCP, a member of the AAA-ATPase superfamily) exclusively in all 61 affected individuals. Haplotype analysis indicated that descent from two founders in two separate North American kindreds accounted for IBMPFD in approximately 50% of affected families. VCP is associated with a variety of cellular activities, including cell cycle control, membrane fusion and the ubiquitin-proteasome degradation pathway. Identification of VCP as causing IBMPFD has important implications for other inclusion-body diseases, including myopathies, dementias and Paget disease of bone (PDB), as it may define a new common pathological ubiquitin-based pathway.
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PMID:Inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia is caused by mutant valosin-containing protein. 1503 82

Marinesco bodies are nuclear inclusions found in pigmented neurons of the substantia nigra and locus ceruleus of humans and monkeys. It has long been known that the frequency of these inclusions increases with advancing age, but no pathologic associations have ever been established. We quantified Marinesco body frequency in human autopsy subjects, classified as young normal controls, elderly controls, dementia with Lewy bodies (DLB), Alzheimer disease (AD), and Parkinson disease (PD). Elderly controls, AD cases, and DLB cases had significantly increased Marinesco body frequencies relative to young controls and DLB cases had significantly increased frequencies relative to elderly controls, while PD cases did not differ from young controls; cases with AD did not differ from elderly controls. Lewy body-containing neurons had significantly higher Marinesco body frequencies than non-Lewy body-containing neurons. Marinesco body frequency in elderly control cases correlated significantly, in inverse fashion, with striatal concentrations of the dopaminergic neuron markers dopamine transporter and tyrosine hydroxylase. These statistical associations suggest that Marinesco bodies constitute or mark a pathologic process that may be related to, or contribute to, age-related motor dysfunction and/or Lewy body disorders. Further studies are needed to ascertain the molecular basis of Marinesco body formation; preliminary studies indicate that proteasome dysfunction can lead to similar abnormalities in cultured cells.
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PMID:Substantia nigra Marinesco bodies are associated with decreased striatal expression of dopaminergic markers. 1509 23

Tau-positive inclusions in neurons are consistent neuropathologic features of the most common causes of dementias such Alzheimer's disease and frontotemporal dementia. Ubiquitinated tau-positive inclusions have been reported in brains of Alzheimer's disease patients, but involvement of the ubiquitin-dependent proteasomal system in tau degradation remains controversial. Before considering the tau degradation in pathologic conditions, it is important to determine whether or not endogenous tau is normally degraded by the proteasome pathway. We therefore investigated this question using two complementary approaches in vitro and in vivo. Firstly, SH-SY5Y human neuroblastoma cells were treated with different proteasome inhibitors, MG132, lactacystin, and epoxomicin. Under these conditions, neither total nor phosphorylated endogenous tau protein levels were increased. Instead, an unexpected decrease of tau protein was observed. Secondly, we took advantage of a temperature-sensitive mutant allele of the 20S proteasome in Drosophila. Genetic inactivation of the proteasome also resulted in a decrease of tau levels in Drosophila. These results obtained in vitro and in vivo demonstrate that endogenous tau is not normally degraded by the proteasome.
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PMID:Tau is not normally degraded by the proteasome. 1579 29

A 97-kDa protein called valosin-containing protein (VCP) has been implicated in osteosarcoma metastasis and Paget's disease of bone, two conditions that complicate the course and outcome of orthopaedic surgery. High VCP gene expression is associated with high metastatic potential in osteosarcoma cells, while loss-of-function VCP mutations cause inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia (IBMPFD). VCP protein expression and regulation have not been examined in normal osteoblasts. The purpose of these studies was to characterize VCP protein expression in control and stressed untransformed osteoblasts. Proteins from confluent MC3T3-E1 mouse osteoblast-like cells were separated by 2D IEF/SDS-PAGE. An abundant spot with a M(r) of 94 kDa and a pI of 5.4 was identified as VCP by MALDI/ToF and peptide mass fingerprint analysis. High constitutive VCP protein expression in subconfluent and confluent resting and mildly physiologically stressed MC3T3-E1 cells was confirmed by Western blotting. When assessed by indirect immunofluorescence in fixed cells or Western blotting of subcellular fractions, VCP was more abundant in the cytoplasm than in the nucleus. Induction of mild physiological stress sufficient to stimulate the ubiquitin-proteasome pathway, which is partially dependent on VCP-mediated targeting of polyubiquitinylated substrates, did not affect steady-state VCP levels or distribution. Thus, VCP is a constitutively abundant protein in untransformed osteoblastic cells under all conditions tested. Such high levels of VCP protein expression in untransformed osteoblastic cells argue against a major causative role for it in metastasis, while the occurrence of Paget's disease in patients with missense VCP mutations supports a major role for VCP in normal osteoblast proliferation and regulation.
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PMID:Identification and characterization of valosin-containing protein (VCP/p97) in untransformed osteoblast-like cells. 1588 83

The activation of the classical complement (C)-system in early-stage Alzheimer disease (AD) and nondemented aging was examined with immunohistochemistry in subjects assessed by the Clinical Dementia Rating (CDR). Activation (staining for C3 and C4 fragments) was found in all brains with amyloid deposits, including all nondemented (CDR 0) cases, with either small numbers of diffuse plaques or with sufficient plaques and tangles to indicate preclinical AD. Staining for C3 and C4 increased in parallel with plaque density in very mild to severe clinical AD. A subset of very mild AD (CDR 0.5) cases also showed C1q (on plaques) and C5b-9 (on neuritic plaques and tangles), whereas these C-fragments were consistently found in severe AD (CDR 3). Mirror section (split-face) analysis showed that C1q, C3, and apoJ (clusterin) occurred on the same plaques. However, C-system regulators CD59, CR1, DAF, and MCP were not detected on plaques or tangles at any stage, indicating that C-activation related to AD is incompletely controlled.
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PMID:Complement activation in very early Alzheimer disease. 1594 22

Autosomal dominant proximal limb girdle or inclusion body myopathy, associated with Paget disease of bone and frontotemporal dementia (IBMPFD) is a recently described disorder that maps to chromosome 9p21.1-p12. We refined the critical locus and identified the gene as the Valosin Containing Protein (VCP) gene, a member of the AAA-ATPase superfamily using a candidate gene approach. Six missense mutations were found to co-segregate with affected individuals only, two of these representing mutation hot spots. We report the clinical and molecular findings in 99 individuals in 13 families. VCP is associated with a variety of cellular activities, including the control of cell cycle, membrane fusion, and the ubiquitin-proteasome degradation pathway. Previous studies have associated VCP mutants in cell lines with vacuole formation and aggregate formation. Identification of VCP as the gene causing IBMPFD has important implications for understanding the pathogenesis of neurodegenerative disorders.
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PMID:Autosomal dominant inclusion body myopathy, Paget disease of bone, and frontotemporal dementia. 1631 58

Mutations in the AAA+ protein (ATPase associated with a variety of cellular activities) p97/VCP (valosin-containing protein) cause a dominantly inherited syndrome of inclusion body myopathy with Paget's disease of the bone and fronto-temporal dementia (IBMPFD). p97/VCP is a ubiquitously expressed protein that participates in a number of cellular processes including endoplasmic reticulum-associated degradation (ERAD). p97/VCP aids in the extraction of ubiquitinated proteins from the endoplasmic reticulum (ER) and facilitates their delivery to the proteasome. This study focuses on the effects of disease-associated p97/VCP mutations on this pathway. We show that p97/VCP containing the most prevalent IBMPFD-associated mutation, R155H, has normal ATPase activity and hexameric structure. However, when expressed in cultured cells, both this and a second IBMPFD-associated p97/VCP mutant increase the overall level of ubiquitin-conjugated proteins and specifically impair degradation of mutant DeltaF508-CFTR handled by the ERAD pathway. These effects are similar to those previously described for an ATPase deficient p97/VCP mutant and suggest that IBMPFD mutations impair p97/VCP cellular function. In a subset of cells, IBMPFD mutations also promote formation of aggregates that contain p97/VCP, ubiquitin conjugates and ER-resident proteins. Undegraded mutant DeltaF508-CFTR also accumulates in these aggregates. We conclude that IBMPFD mutations in p97/VCP disrupt ERAD and that this may contribute to the pathogenesis of IBMPFD.
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PMID:Inclusion body myopathy-associated mutations in p97/VCP impair endoplasmic reticulum-associated degradation. 1632 91

Parkinson disease (PD) and dementia with Lewy bodies (DLB) are characterized by the accumulation of abnormal alpha-synuclein and ubiquitin in protein aggregates conforming Lewy bodies and Lewy neurites. Ubiquitin C-terminal hydrolase-1 (UCHL-1) disassembles polyubiquitin chains to increase the availability of free monomeric ubiquitin to the ubiquitin proteasome system (UPS) thus favoring protein degradation. Since mutations in the UCHL-1 gene, reducing UPS activity by 50%, have been reported in autosomal dominant PD, and UCHL-1 inhibition results in the formation of alpha-synuclein aggregates in mesencephalic cultured neurons, the present study was initiated to test UCHL-1 mRNA and protein levels in post-mortem frontal cortex (area 8) of PD and DLB cases, compared with age-matched controls. TaqMan PCR assays, and Western blots demonstrated down-regulation of UCHL-1 mRNA and UCHL-1 protein in the cerebral cortex in DLB (either in pure forms, not associated with Alzheimer disease: AD, and in common forms, with accompanying AD changes), but not in PD, when compared with age-matched controls. Interestingly, UCHL-1 mRNA and protein expressions were reduced in the medulla oblongata in the same PD cases. Moreover, UCHL-1 protein was decreased in the substantia nigra in cases with Lewy body pathology. UCHL-1 down-regulation was not associated with reduced protein levels of several proteasomal subunits, including 20SX, 20SY, 19S and 11Salpha. Yet UCHL-3 expression was reduced in the cerebral cortex of PD and DLB patients. Together, these observations show reduced UCHL-1 expression as a contributory factor in the abnormal protein aggregation in DLB, and points UCHL-1 as a putative therapeutic target in the treatment of DLB.
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PMID:Reduced ubiquitin C-terminal hydrolase-1 expression levels in dementia with Lewy bodies. 1638 Feb 64

Alzheimer's disease is a genetically complex disorder associated with multiple genetic defects, either mutational or of susceptibility. Although potentially associated with an accelerated stochastically driven aging process, Alzheimer's disease is an independent clinical entity in which the aging process exerts a deleterious effect on brain activity in conjunction with polymodal genetic factors and other pathological conditions (i.e., age-related cerebrovascular deterioration) and environmental factors (i.e., nutrition). Alzheimer's disease genetics does not explain in full the etiopathogenesis of this disease. Therefore, it is likely that environmental factors and/or epigenetic phenomena also contribute to Alzheimer's disease pathology and phenotypic expression of dementia. The genomics of Alzheimer's disease is still in its infancy, but this field is aiding the understanding of novel aspects of this disease, including genetic epidemiology, multifactorial risk factors, pathogenic mechanisms associated with genetic networks and genetically regulated metabolic cascades. Alzheimer's disease genomics is also helping to develop new strategies in pharmacogenomic research and prevention. Functional genomics, proteomics, pharmacogenomics, high-throughput methods, combinatorial chemistry and modern bioinformatics will greatly contribute to accelerate drug development for Alzheimer's disease and other complex disorders. The multifactorial genetic dysfunction in dementia includes mutational loci (APP, PS1, PS2, TAU) and diverse susceptibility loci (APOE, alpha2M, alphaACT, LRP1, IL1 alpha, TNF, ACE, BACE, BCHE, CST3, MTHFR, GSK3 beta, NOS3 and many other genes) distributed across the human genome, probably converging in a common pathogenic mechanism that leads to premature neuronal death, in which mitochondrial DNA mutations may contribute to increased genetic variability and heterogeneity. In Alzheimer's disease, multiple pathogenic events, including genetic factors, accumulation of aberrant or misfolded proteins, protofibril formation, ubiquitin-proteasome system dysfunction, excitotoxic reactions, oxidative and nitrosative stress, mitochondrial injury, synaptic failure, altered metal homeostasis, dysfunction of axonal and dendritic transport, and chaperone misoperation may converge in pathogenic pathways leading to premature death and neurodegeneration. Some of these mechanisms are common to several neurodegenerative disorders, which differ depending upon the gene(s) affected and the involvement of specific genetic networks, together with epigenetic factors and environmental events. Many genes potentially associated with Alzheimer's disease in some studies cannot be confirmed as candidate genes in replication studies, indicating that methodological problems and genomic complexity are leading to erroneous conclusions. A different approach to Alzheimer's disease functional genomics is to integrate individual genetic information in polygenic genotypes (haplotype-like model) and to investigate genotype-phenotype correlations and genotype-related pharmacogenomic behaviors. The application of functional genomics to Alzheimer's disease can be a suitable strategy for molecular diagnosis and for understanding pathophysiological mechanisms associated with Alzheimer's disease-related neurodegeneration. Furthermore, the pharmacogenomics of Alzheimer's disease may contribute in the future to optimize drug development and therapeutics, increasing efficacy and safety, and reducing side-effects and unnecessary costs.
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PMID:Molecular genetics of Alzheimer's disease and aging. 1647 Feb 48


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