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)

Pseudomonas aeruginosa and Serratia marcescens can cause refractory keratitis resulting in corneal perforation and blindness. These bacteria produce various kinds of proteases. In addition to pseudomonal elastase (LasB) and alkaline protease, LasA protease and protease IV have recently been found to be more important virulence factors of P. aeruginosa . S. marcescens produces a cysteine protease in addition to metalloproteases. These bacterial proteases have a number of biological activities, such as degradation of tissue constituents and host defense-oriented proteins, as well as activation of zymogens (Hageman factor, prekallikrein and pro-matrix metalloproteinases) through limited proteolysis. In this article, the properties of these bacterial proteases are reviewed and the pathogenic roles of these proteases in pseudomonal keratitis are discussed.
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PMID:Role of bacterial proteases in pseudomonal and serratial keratitis. 1557 20

Visible senescence of the flag tepals in Iris x hollandica (cv. Blue Magic) was preceded by a large increase in endoprotease activity. Just before visible senescence about half of total endoprotease activity was apparently due to cysteine proteases, somewhat less than half to serine proteases, with a minor role of metalloproteases. Treatment of isolated tepals with the purported serine protease inhibitors AEBSF [4-(2-aminoethyl)-benzenesulfonyl fluoride] or DFP (diisopropyl-fluorophosphate) prevented the increase in endoprotease activity and considerably delayed or prevented the normal senescence symptoms. The specific cysteine protease-specific E-64d reduced maximum endoprotease activity by 30%, but had no effect on the time to visible senescence. Zinc chloride and aprotinin reduced maximum endoprotease activity by c. 50 and 40%, respectively, and slightly delayed visible senescence. A proteasome inhibitor (Z-leu-leu-Nva-H) slightly delayed tepal senescence, which indicates that protein degradation in the proteasome may play a role in induction of the visible senescence symptoms. It is concluded that visible senescence is preceded by large-scale protein degradation, which is apparently mainly due to cysteine- and serine protease activity, and that two (unspecific) inhibitors of serine proteases considerably delay the senescence symptoms.
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PMID:Delay of Iris flower senescence by protease inhibitors. 1572 Jun 58

Loss of function mutations in the gene (CSTB) encoding human cystatin B, a widely expressed cysteine protease inhibitor, are responsible for a severe neurological disorder known as an Unverricht-Lundborg disease (EPM1). EPM1 had been linked to chromosome 21q22.3 in Finnish families and it is an autosomal recessive inherited disorder with a homozygous minisatellite expansion in the cystatin B gene (stefin B gene). This disease is difficult to treat because it is refractory to most antiepileptic drugs and using multiple medications had been unsuccessful so far. To come a step closer to understanding of the nature of this disease, especially about the events on the molecular level, in vitro properties of missense EPM1 mutant G4R were determined. It was observed that the mutant has a prolonged lag phase of fibrillation at the same protein stability, which could indicate it were more toxic to the cells. Similar experiments with the N-terminal fragment of 67 aminoacid residues are ongoing, showing higher propensity to aggregate. Therefore, a hypothesis is launched that at least in a subset of Unverricht-Lundborg disease patients, cystatin B protein may aggregate in the cell. Protein aggregation can be secondary to external insults or aging, however, inherited forms of neurodegenerative diseases, such as familial Parkinson's, Huntington's or familial Alzheimer's disease, are directly linked to the mutant proteins aggregation. Protein aggregates in the form of amyloid plaques, neurofibrilary tangles, intra-cytoplasmic or intra-nuclear inclusions lead to increased production of the reactive oxygen species and dysfunction of the ubiquitine/proteasome system. Finally, mitochondrial dysfunction and cell death are observed. Certainly, it remains to be checked by experiments whether overexpression in cell culture of the missense mutants G4R and N-terminal fragment to residue 68 lead to cellular inclusions and the accompanying changes characteristic for the conformational disorders.
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PMID:Protein aggregation as a possible cause for pathology in a subset of familial Unverricht-Lundborg disease. 1578 Apr 91

Plant pathogenic Pseudomonas syringae deliver type III effector proteins into the host cell, where they function to manipulate host defense and metabolism to benefit the extracellular bacterial colony. The activity of these virulence factors can be monitored by plant disease resistance proteins deployed to "guard" the targeted host proteins. The Arabidopsis RIN4 protein is targeted by three different type III effectors. Specific manipulation of RIN4 by each of them leads to activation of either the RPM1 or RPS2 disease resistance proteins. The type III effector AvrRpt2 is a cysteine protease that is autoprocessed inside the host cell where it activates RPS2 by causing RIN4 disappearance. RIN4 contains two sites related to the AvrRpt2 cleavage site (RCS1 and RCS2). We demonstrate that AvrRpt2-dependent cleavage of RIN4 at RCS2 is functionally critical in vivo. This event leads to proteasome-mediated elimination of all but a membrane-embedded approximately 6.4-kDa C-terminal fragment of RIN4. One or more of three consecutive cysteines in this C-terminal fragment are required for RIN4 localization; these are likely to be palmitoylation and/or prenylation sites. AvrRpt2-dependent cleavage at RCS2, and release of the remainder of RIN4 from the membrane, consequently prevents RPM1 activation by AvrRpm1 or AvrB. RCS2 is contained within the smallest tested fragment of RIN4 that binds AvrB in vitro. Thus, at least two bacterial virulence factors target the same domain of RIN4, a approximately 30-aa plant-specific signature sequence found in a small Arabidopsis protein family that may be additional targets for these bacterial virulence factors.
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PMID:The Pseudomonas syringae effector AvrRpt2 cleaves its C-terminally acylated target, RIN4, from Arabidopsis membranes to block RPM1 activation. 1584 64

After specific activation, CD8+ cytotoxic T lymphocytes (CTLs) enter a refractory state termed activation-induced nonresponsiveness (AINR) that is characterized by the inability of T cells to respond to a secondary stimulus. Here, we show that T cell receptor triggering results in rapid degradation of the src-family protein kinase lck through a mechanism that is proteasome- and lysosome-independent, sensitive to cysteine protease inhibitors, and distinct from the pathways involved in degradation of ZAP-70 kinase or zeta-chain of the CD3 complex. Pharmacologic blockade of lck degradation, as well as transfection of refractory cells with an lck expression vector, increased responsiveness of CTLs to repeated antigenic challenge. The development or maintenance of AINR was not affected by exogenously added IL-2, whereas IL-15 or IFN-alpha restored both lck expression and responsiveness of preactivated CTLs. Our results suggest that lck degradation plays an important role in the development of AINR in human CTLs and that this condition can be reverted by pharmacologic agents or lymphokines that prevent lck degradation or induce its expression.
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PMID:Regulation of lck degradation and refractory state in CD8+ cytotoxic T lymphocytes. 1595 29

The Josephin domain plays an important role in the cellular functions of ataxin-3, the protein responsible for the neurodegenerative Machado-Joseph disease. We have determined the solution structure of Josephin and shown that it belongs to the family of papain-like cysteine proteases, sharing the highest degree of structural similarity with bacterial staphopain. A currently unique structural feature of Josephin is a flexible helical hairpin formed by a 32-residue insertion, which could determine substrate specificity. By using the Josephin structure and the availability of NMR chemical shift assignments, we have mapped the enzyme active site by using the typical cysteine protease inhibitors, transepoxysuccinyl-L-eucylamido-4-guanidino-butane (E-64) and [L-3-trans-(propylcarbamyl)oxirane-2-carbonyl]-L-isoleucyl-L-proline (CA-074). We also demonstrate that the specific interaction of Josephin with the ubiquitin-like domain of the ubiquitin- and proteasome-binding factor HHR23B involves complementary exposed hydrophobic surfaces. The structural similarity with other deubiquitinating enzymes suggests a model for the proteolytic enzymatic activity of ataxin-3.
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PMID:The solution structure of the Josephin domain of ataxin-3: structural determinants for molecular recognition. 1602 May 35

c-Fos is an immediate early gene type proto-oncogene that belongs to the AP (activator protein)-1 transcription factor family. Gene knockout experiments have demonstrated that, among the Fos family, only c-Fos is indispensable for osteoclast differentiation but that c-Fos can be substituted for by other Fos family members including FosB/DeltaFosB, Fra-1 and Fra-2, in most other tissues and cells. To further understand a unique role of c-Fos in osteoclastogenesis, we investigated the temporal profile and regulatory mode of expression of c-Fos during the course of osteoclast differentiation. The results indicated that c-Fos protein gradually increased in preosteoclasts during differentiation to a greater extent than that of mRNA induction. We then determined the proteolytic pathway of c-Fos conferring unstable nature on c-Fos protein in a preosteoclastic cell line, RAW264.7. Proteasome inhibitors including MG132 and Z-LLF caused a rapid increase in c-Fos protein expression in these cells within several hours, but other inhibitors of cysteine protease (E-64), lysosome (chloroquine) and calpain (ALLM) did not. Moreover, the proteasome inhibitors caused an extensive accumulation of ubiquitinated c-Fos protein and an approximately three-fold extension of the c-Fos protein half-life. We therefore conclude that the ubiquitin-proteasome system is the major proteolytic pathway conferring instability on c-Fos protein in preosteoclasts. Our results further imply that c-Fos stabilization due to dynamic changes in the ubiquitin-proteasome-dependent degradation may be involved in the accumulation of c-Fos protein in differentiating preosteoclasts.
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PMID:c-Fos degradation by the ubiquitin-proteasome proteolytic pathway in osteoclast progenitors. 1617 35

We herein describe the development of a Bacillus subtilis system that can be used to produce large quantities of recombinant (r-) human salivary cystatins, a cysteine protease inhibitor of family 2 in the cystatin superfamily. The B. subtilis that lacked the alkaline protease E gene (DeltaaprE type mutant strain) was prepared by homologous recombination. The cDNA fragments coding for mature cystatins (S and SA) were ligated in frame to the DNA segment for the signal peptide of endoglucanase in the pHSP-US plasmid vector that was then use to transform the DeltaaprE type mutant strain of B. subtilis. The transformants carrying the expression vectors were cultivated in 5-L jar fermenters for 3 days at 30 degrees C. Both r-cystatin S and r-cystatin SA were successfully expressed and secreted into the culture broth, and were purified using a fast performance liquid chromatography system. The first use of DeltaaprE type mutant strain of B. subtilis made it possible to obtain a high yield of secreted protein, which makes this system an improvement over expression in Escherichia coli. We conclude that this system has high utility for expression of commercial quantities of secreted proteins.
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PMID:Extracellular production of human cystatin S and cystatin SA by Bacillus subtilis. 1673 25

We previously showed that the one-electron reduction product of nitric oxide (NO), nitroxyl (HNO), irreversibly inhibits the proteolytic activity of the model cysteine protease papain. This result led us to investigate the differential effects of the nitrogen oxides, such as nitroxyl (HNO), NO, and in situ-generated peroxynitrite on cysteine modification-sensitive cellular proteolytic enzymes. We used Angeli's salt, diethylaminenonoate (DEA/NO), and 3-morpholinosydnoniminehydrochloride (SIN-1), as donors of HNO, NO, and peroxynitrite, respectively. In this study we evaluated their inhibitory activities on the lysosomal mammalian papain homologue cathepsin B and on the cytosolic 26S proteasome in THP-1 monocyte/macrophages after LPS activation or TPA differentiation. HNO-generating Angeli's salt caused a concentration-dependent (62 +/- 4% at 316 muM) inhibition of the 26S proteasome activity, resulting in accumulation of protein-bound polyubiquitinylated proteins in LPS-activated cells, whereas neither DEA/NO nor SIN-1 showed any effect. Angeli's salt, but not DEA/NO or SIN-1, also caused (94 +/- 2% at 316 muM) inhibition of lysosomal cathepsin B activity in LPS-activated cells. Induction of macrophage differentiation did not significantly alter the inhibitory effect of HNO on lysosomal cathepsin B activity, but protected the proteasome from HNO-induced inhibition. The protection awarded by macrophage differentiation was associated with induction of the GSH synthesis rate-limiting enzyme gamma-glutamylcysteine synthetase, as well as with increased intracellular GSH. In conclusion, HNO abrogates both lysosomal and cytosolic proteolysis in THP-1 cells. Macrophage differentiation, associated with upregulation of antioxidant defenses such as increased cellular GSH, does not protect the lysosomal cysteine protease cathepsin B from inhibition.
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PMID:Cathepsin B is a differentiation-resistant target for nitroxyl (HNO) in THP-1 monocyte/macrophages. 1678 60

By comparing mRNA profiles in cultured fibroblasts from patients affected with lysosomal storage diseases, we identified differentially expressed genes common to these conditions. These studies, confirmed by biochemical experiments, demonstrated that lysosomal storage is associated with downregulation of ubiquitin C-terminal hydrolase, UCH-L1 in the cells of eight different lysosomal disorders, as well as in the brain of a mouse model of Sandhoff disease. Induction of lysosomal storage by the cysteine protease inhibitor E-64 also reduced UCH-L1 mRNA, protein level and activity. All cells exhibiting lysosomal storage contained ubiquitinated protein aggregates and showed reduced levels of free ubiquitin and decreased proteasome activity. The caspase-mediated apoptosis in E-64-treated fibroblasts was reversed by transfection with a UCH-L1 plasmid, and increased after downregulation of UCH-L1 by siRNA, suggesting that UCH-L1 deficiency and impairment of the ubiquitin-dependent protein degradation pathway can contribute to the increased cell death observed in many lysosomal storage disorders.
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PMID:Altered gene expression in cells from patients with lysosomal storage disorders suggests impairment of the ubiquitin pathway. 1688 48


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