Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002736 (amyotrophic lateral sclerosis)
 19,048 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the effect of two proteasome inhibitors, lactacystin and epoxomicin, on cultured spinal cord neurons. The incubation of spinal neurons with proteasome inhibitors for 24 hr induced neurotoxicity in a dose-dependent manner. We found motor neurons to be more vulnerable to proteasome-induced neurotoxicity than nonmotor neurons. The staining of cell bodies in treated motor neurons was markedly disrupted and showed characteristic granular patterns. Proteasome-induced neurotoxicity is accompanied by apoptotic nuclear changes, posttranslational modification of the cellular proteins, generation of intracellular free radicals, reduction in the amount of reduced glutathione, and mitochondrial dysfunction. Neurotoxicity was reduced by the administration of low concentrations (1-100 nM) of geranylgeranylacetone (GGA), which is widely used as an antiulcer drug, although higher concentrations of this drug produced neurotoxicity in spinal cord neurons. GGA was found to induce the expression of heat shock protein 70 as well as thioredoxin, which may partly contribute to the protective effect of GGA. These data suggest that the inhibition of proteasome may play a role in the mechanism of neurodegenerative diseases of the spinal cord, such as amyotrophic lateral sclerosis, and that the use of GGA may be effective in the treatment of these conditions.
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PMID:Effect of geranylgeranylaceton on cellular damage induced by proteasome inhibition in cultured spinal neurons. 1212 78

Aggregates of Cu/Zn superoxide dismutase (SOD) have been demonstrated in familial amyotrophic lateral sclerosis (FALS) and other neurodegenerative diseases; however, their role in disease pathogenesis is unclear. In this study, we investigated the presence of SOD aggregates in nerve growth factor (NGF)-differentiated PC12 cells and cell viability following: (i) transduction with replication-deficient recombinant adenoviruses (AdVs) expressing wild-type SOD (SODWT) or mutant SOD (SODMT, V148G or A4V); (ii) transfection of yellow fluorescent protein-tagged SODWT (SODWT-YFP) or SODMT (SODA4V-YFP, SODV148G-YFP). SOD aggregates were more prominent in cells following transduction of AdSODMT than AdSODWT and following treatment with H2O2, suggesting that mutant SOD leads to oxidation of cellular components. In addition, cells expressing SODMT-YFP yielded SOD aggregates that were significantly larger and more frequent than SOD aggregates in cells expressing SODWT-YFP. Proteasome inhibitors, but not cathepsin B inhibitors, increased aggregate formation but did not increase cell death. In addition, treatments that increased cell viability did not significantly decrease SOD aggregates. Taken together, our data demonstrate that there is no association between SOD aggregates and cell death in FALS.
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PMID:No correlation between aggregates of Cu/Zn superoxide dismutase and cell death in familial amyotrophic lateral sclerosis. 1235 70

Accumulating evidence indicates that abnormal conformation of mutant superoxide dismutase 1 (SOD1) is an essential feature underlying the pathogenesis of mutant SOD1-linked familial amyotrophic lateral sclerosis (ALS). Here we investigated the role of ubiquitin-proteasome pathway in the mutant SOD1-related cell death and the effect of oxidative stress on the misfolding of mutant SOD1. Transient overexpression of ubiquitin with human SOD1 (wild-type, ala4val, gly85arg, gly93ala) in Neuro2A cells decreased the amount of mutant SOD1, but not of wild-type, while only mutants were co-immunoprecipitated with poly-ubiquitin. Proteasome inhibition by lactacystin augmented accumulation of mutant SOD1 in the non-ionic detergent-insoluble fraction. The spinal cord lysates from mutant SOD1 transgenic mice showed multiple carbonylated proteins, including mutant SOD1 with SDS-resistant dimer formation. Furthermore, the treatment of hSOD1-expressing cells with hydrogen peroxide promoted the oligomerization, and detergent-insolubility of mutant SOD1 alone, and the oxidized mutant SOD1 proteins were more heavily poly-ubiquitinated. In Neuro2A cells stably expressing human SOD1 protein, the proteasome function measured by chymotrypsin-like activity, was decreased over time without a quantitative alteration of the 20S proteasomal component. Finally, primary motor neurons from the mouse embryonic spinal cord were more vulnerable to lactacystin than non-motor neurons. These results indicate that the sustained expression of mutant SOD1 leads to proteasomal inhibition and motor neuronal death, which in part explains the pathogenesis of mutant SOD1-linked ALS.
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PMID:Proteasomal inhibition by misfolded mutant superoxide dismutase 1 induces selective motor neuron death in familial amyotrophic lateral sclerosis. 1243 74

Injury to motor neurons associated with mutant Cu,Zn-superoxide dismutase (SOD1)-related familial amyotrophic lateral sclerosis (FALS) results from a toxic gain-of-function of the enzyme. The mechanisms by which alterations to SOD1 elicit neuronal death remain uncertain despite intensive research effort. Analysis of the cellular proteins that are differentially expressed in the presence of mutant SOD1 represents a novel approach to investigate further this toxic gain-of-function. By using the motor neuron-like cell line NSC34 stably transfected with wild-type, G93A, or G37R mutant human SOD1, we investigated the effects of mutant human SOD1 on protein expression using proteomic approaches. Seven up-regulated proteins were identified as argininosuccinate synthase, argininosuccinate lyase, neuronal nitric-oxide synthase, RNA-binding motif protein 3, peroxiredoxin I, proteasome subunit beta 5 (X), and glutathione S-transferase (GST) Alpha 2. Seven down-regulated proteins were identified as GST Mu 1, GST Mu 2, GST Mu 5, a hypothetical GST Mu, GST Pi B, leukotriene B(4) 12-hydroxydehydrogenase, and proteasome subunit beta5i (LMP7). GST assays demonstrated a significant reduction in the total GST activity of cells expressing mutant human SOD1. Proteasome assays demonstrated significant reductions in chymotrypsin-like, trypsin-like, and post-glutamylhydrolase proteasome activities. Laser capture microdissection of spinal cord motor neurons from human FALS cases, in conjunction with reverse transcriptase-PCR, demonstrated decreased levels of mRNA encoding GST Mu 1, leukotriene B(4) 12-hydroxydehydrogenase, and LMP7. These combined approaches provide further evidence for involvement of alterations in antioxidant defenses, proteasome function, and nitric oxide metabolism in the pathophysiology of FALS.
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PMID:Analysis of the cytosolic proteome in a cell culture model of familial amyotrophic lateral sclerosis reveals alterations to the proteasome, antioxidant defenses, and nitric oxide synthetic pathways. 1247 80

Accumulation of ubiquitinated proteins in inclusions is common to various neurodegenerative disorders such as Parkinson's disease, Alzheimer's disease and amyotrophic lateral sclerosis, although it occurs in selective neurons in each disease. The mechanisms generating such abnormal aggregates and their role in neurodegeneration remain unclear. Inclusions appear in familial and non-familial cases of neurodegenerative disorders, suggesting that factors other than particular mutations contribute to protein accumulation and aggregation. Proteasome impairment triggered by aging or conditions such as oxidative stress may contribute to protein accumulation and aggregation in neurodegeneration. To test this hypothesis in mouse neuronal cells, we overexpressed a 20S proteasome beta5 subunit with an active site mutation. The N-terminal threonine to alanine substitution resulted in impairment of the chymotrypsin-like activity, which is a rate-limiting step in protein degradation by the proteasome. The Thr1Ala mutation was not lethal under homeostatic conditions. However, this single amino acid substitution significantly hypersensitized the cells to oxidative stress, triggering not only the accumulation and aggregation of ubiquitinated proteins, including synuclein, but also cell death. Our results demonstrate that this genetic manipulation of proteasome activity involving a single amino acid substitution causes the formation of protein aggregates in stressed neuronal cells independently of the occurrence of mutations in other cellular proteins. These results support the notion that proteasome disruption may be central to the development of familial as well as sporadic cases of neurodegeneration.
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PMID:A single amino acid substitution in a proteasome subunit triggers aggregation of ubiquitinated proteins in stressed neuronal cells. 1519 63

Ubiquitinated inclusions are a constant feature of amyotrophic lateral sclerosis (ALS). It has been hypothesised that these inclusions reflect overload or failure of the ubiquitin-proteasome system, and that this failure contributes to the degeneration of motor neurons. In the present study we have examined the effect of low concentrations of proteasome inhibitors on protein aggregation and viability of neurons in organotypical spinal cord cultures. We found a dose-dependent degeneration of neurons after a one-week exposure to the proteasome inhibitors lactacystin and epoxomicin. Neuronal degeneration was associated with an increase in poly-ubiquitination, consistent with failure of the ubiquitin-proteasome system. Proteasome inhibition caused degeneration of both motor neurons and interneurons, and no difference in survival between motor neurons and interneurons was observed. Since protein aggregation may particularly play a role in ALS patients with superoxide dismutase 1 (SOD1) mutations, we have compared the effect of proteasome inhibition between spinal cord cultures from non-transgenic and SOD1(G93A) transgenic mice. There was no difference between the viability of motor neurons from transgenic and non-transgenic mice.
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PMID:Long term proteasome inhibition does not preferentially afflict motor neurons in organotypical spinal cord cultures. 1520 19

Proteasome, ubiquitin, GFAP and neurofilament were evaluated in motorneurons and astrocytes of spinal cords of ALS and control cases. ALS neurons exhibited ubiquitin positive inclusions and areas of strong immunoreaction for proteasome. Areas of proteasome stain were observed close to neurofilament positive proximal process enlargement. The percentage of neurons strongly immunoreacted, for proteasome was higher in ALS cases than in controls. Many astrocytes were positive for ubiquitin and proteasome. These results suggest that the ubiquitin-proteasome pathway is involved in the ALS pathogenesis and agree with the view that ALS is a disorder of protein aggregation that affects neurons and nonneuronal cells.
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PMID:Expression of ubiquitin and proteasome in motorneurons and astrocytes of spinal cords from patients with amyotrophic lateral sclerosis. 1680 3

We report phosphorylated and ubiquitinated aggregates of TAR DNA binding protein of 43 kDa (TDP-43) in SH-SY5Y cells similar to those in brains of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U). Two candidate sequences for the nuclear localization signal were examined. Deletion of residues 78-84 resulted in cytoplasmic localization of TDP-43, whereas the mutant lacking residues 187-192 localized in nuclei, forming unique dot-like structures. Proteasome inhibition caused these to assemble into phosphorylated and ubiquitinated TDP-43 aggregates. The deletion mutants lacked the exon skipping activity of cystic fibrosis transmembrane conductance regulator (CFTR) exon 9. Our results suggest that intracellular localization of TDP-43 and proteasomal function may be involved in inclusion formation and neurodegeneration in TDP-43 proteinopathies.
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PMID:Phosphorylated and ubiquitinated TDP-43 pathological inclusions in ALS and FTLD-U are recapitulated in SH-SY5Y cells. 1911 50

TAR DNA binding protein of 43 kDa (TDP-43) was identified as a major component of the ubiquitin-positive inclusions found in frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). To investigate the molecular mechanisms underlying the formation of intracellular aggregates of TDP-43, we have established cellular models of intracellular TDP-43 aggregates similar to the pathological inclusions found in the brain FTLD and ALS patients. Deletion of the sequences near the nuclear localization signal resulted in cytoplasmic localization of TDP-43, whereas deletion mutants that lack the region around the RNA recognition motif localized in the nuclei, forming unique dot-like structures. Proteasome inhibition caused these structures to assemble into round aggregates that are reactive with anti-phosphorylated TDP-43 and anti-ubiquitin antibodies. Green fluorescent protein (GFP)-tagged N-terminal or C-terminal fragments of TDP-43 also promoted the formation of the abnormal intracellular inclusions. Co-expression of DsRed-tagged full-length TDP-43 with GFP-tagged C-terminal fragments of TDP-43 causes the formation of cytoplasmic inclusions that are positive for both GFP and DsRed. Cells with GFP and DsRed positive inclusions were nagative for normal nuclear staining for endogenous TDP-43. These results suggest that GFP-tagged C-terminal fragments of TDP-43 are bound not only to transfected DsRed-full-length TDP-43 but also to endogenous TDP-43. Endogenous TDP-43 may also be included in the cytoplasmic aggregates of TDP-43 C-terminal fragments, which results in the failure of its nuclear localization and therefore inhibits its function. We propose that the generation and aggregation of phosphorylated C-terminal fragments of TDP-43 play a primary role in the formation of inclusions, and the resultant loss of normal TDP-43 localization leads to neuronal degeneration in TDP-43 proteinopathy.
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PMID:[The molecular mechanisms of intracellular TDP-43 aggregates]. 1993 86

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are characterized by intraneuronal deposition of the nuclear TAR DNA-binding protein 43 (TDP-43) caused by unknown mechanisms. Here, we studied TDP-43 in primary neurons under different stress conditions and found that only proteasome inhibition by MG-132 or lactacystin could induce significant cytoplasmic accumulation of TDP-43, a histopathological hallmark in disease. This cytoplasmic accumulation was accompanied by phosphorylation, ubiquitination and aggregation of TDP-43, recapitulating major features of disease. Proteasome inhibition produced similar effects in both hippocampal and cortical neurons, as well as in immortalized motor neurons. To determine the contribution of TDP-43 to cell death, we reduced TDP-43 expression using small interfering RNA (siRNA), and found that reduced levels of TDP-43 dose-dependently rendered neurons more vulnerable to MG-132. Taken together, our data suggests a role for the proteasome in subcellular localization of TDP-43, and possibly in disease.
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PMID:Cytoplasmic accumulation and aggregation of TDP-43 upon proteasome inhibition in cultured neurons. 2182 35


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