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)

The mouse cDNA homologues of the rat C2, C9, and C5 subunits of the multicatalytic proteinase have been cloned and expressed in bacteria. The respective recombinant proteins were purified and used to produce specific anti-subunit antibodies. Immunoblotting of two-dimensional gels of purified rat liver multicatalytic proteinase showed that the C2 (32-kDa) and C9 (29-kDa) polypeptides are resolved into three and two isoelectric variants, respectively, likely due to post-translational modifications, i.e. phosphorylation, and the presence of two anti-C5 reacting polypeptides (25.5 and 23 kDa). Epitope mapping of the anti-C2-specific antibody with different constructs of the recombinant C2 protein allowed us to determine that one major epitope of this anti-C2 antibody is located within the last 9-11 amino acids of the C2 polypeptide. Affinity purified antibodies directed against the C2 COOH-terminal were able to discriminate the active and latent forms of the multicatalytic proteinase, supporting the conclusion that the C2 protein found in the active form of the enzyme is a polypeptide of 28 kDa, produced by the loss, at least, of the last 9-13 amino acids (DEPAEKADEPMEH) of the intact C2 (32-kDa) component. By in vitro treatment of the latent form of the enzyme with elastase, we show the conversion of the C2 (32-kDa) component to a 28-kDa protein with loss of recognition by the anti-C2 COOH-terminal affinity purified antibodies, but this limited degradation of the C2 component did not have any significant effect on the proteolytic activity (assayed with myelin basic protein and fluorogenic peptides) of the multicatalytic proteinase. It is suggested that the proteolytic cleavage of the C2 COOH-terminal region may be involved in the regulation of the interaction of the multicatalytic proteinase with other cellular proteins and/or in the translocation of the complex to the nucleus.
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PMID:Antibodies against the C2 COOH-terminal region discriminate the active and latent forms of the multicatalytic proteinase complex. 817 1

A ubiquitin(Ub)/ATP-dependent proteolytic complex (26S proteasome) was highly purified from the rat brain. The brain 26S proteasome consisted of 22-110 kDa subunits characteristic of the typical 26S proteasome on the basis of SDS-PAGE. The two-dimensional PAGE (NEPHGE and SDS-PAGE) pattern revealed that the pI values and molecular masses of the brain 26S proteasome subunits were similar to those of the subunits of 26S proteasomes purified from the rat liver and skeletal muscles. The enzymatic properties of the brain 26S proteasome were similar to those of the liver complex and also to the Ub-conjugate degrading activity in the cerebral cortex extract. Furthermore, it was found that the brain 26S proteasome was capable of degrading the myelin basic protein in a Ub-dependent manner. These results indicate that the brain contains the Ub-conjugate-degrading 26S proteasome, the subunit composition of which appears similar to those of the other tissues, and that the myelin basic protein may be a candidate physiological substrate for the brain 26S proteasome.
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PMID:Purification and properties of the 26S proteasome from the rat brain: evidence for its degradation of myelin basic protein in a ubiquitin-dependent manner. 881 59

The effect of indomethacin, a non-steroidal anti-inflammatory drug upon purified calpain has been studied. Also, its effects upon Ca2+-mediated degradation of cytoskeletal proteins (neurofilament) in spinal cord homogenate has been investigated. A dose-dependent inhibition of purified calpain activity was observed. A 50% inhibition of 14C-caseinolytic activity was obtained with less than 1.1 mM of indomethacin while the activity was completely inhibited at 3.3 mM concentration. The inhibitory effect of ketorlac, another non-steroidal anti-inflammatory drug, upon calpain was weaker than that of indomethacin. The degradation of myelin basic protein (MBP) by cathepsin B, a lysosomal cysteine protease, was significantly inhibited by indomethacin. It also inhibited the Ca2+-mediated degradation of neurofilament protein (NFP) in spinal cord homogenate. The extent of NFP degradation was analyzed by SDS-PAGE and the inhibition shown by indomethacin was weaker than that observed with leupeptin and the calpain inhibitor E64-d. The inhibitory effect of indomethacin on the activity of multicatalytic proteinase complex was negligible. These results suggest that indomethacin, a non-steroidal anti-inflammatory drug and cyclooxygenase inhibitor also inhibits proteinases, including cathepsin B and calpain.
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PMID:Inhibition of proteolysis by a cyclooxygenase inhibitor, indomethacin. 1107 71

We have used lactacystin, a specific inhibitor of the 26S proteasome, in oligodendroglial cell (OLGc) primary cultures to explore the possible participation of the proteasome-ubiquitin-dependent pathway in the decision of the OLGcs to arrest their proliferation and start differentiation. Addition of lactacystin at various concentrations to cultures containing a majority of OLGc was found to produce their withdrawal from the cell cycle and to induce their biochemical and morphological differentiation, with the appearance of extensive myelin-like sheets. The three classic proteolytic activities of the proteasome were significantly decreased in the lactacystin-treated cultures, and the immunocytochemical analysis showed an increase in the number of O4-, O1-, myelin basic protein-, and myelin proteolipid protein-positive cells and a decrease in A2B5-reacting cells. Quantitative immunochemical evaluation of the expression of certain proteins controlling the cell cycle showed an increase in p27kip1-, cyclin D-, and cdk4-positive cells, with a decrease in cyclin E- and cdk2-positive cells. In the lactacystin-treated OLGcs, there was a dose-dependent decrease in the number of cells incorporating bromodeoxyuridine and in the activity of the complexes cyclin D-cdk4 and cyclin E-cdk2. Furthermore, increased levels of expression of several STAT factors were found, suggesting that proteasome inhibition in OLGcs could stabilize signals of survival and differentiation that might be processed through the JAK/STAT signaling cascade.
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PMID:Inhibition of the proteasome by lactacystin enhances oligodendroglial cell differentiation. 1280 3

Accumulation of misfolded proteins and alterations in the ubiquitin-proteasome pathway are associated with various neurodegenerative conditions of the CNS and PNS. Aggregates containing ubiquitin and peripheral myelin protein 22 (PMP22) have been observed in the Trembler J mouse model of Charcot-Marie-Tooth disease type 1A demyelinating neuropathy. In these nerves, the turnover rate of the newly synthesized PMP22 is reduced, suggesting proteasome impairment. Here we show evidence of proteasome impairment in Trembler J neuropathy samples compared with wild-type, as measured by reduced degradation of substrate reporters. Proteasome impairment correlates with increased levels of polyubiquitinated proteins, including PMP22, and the recruitment of E1, 20S and 11S to aggresomes formed either spontaneously due to the Trembler J mutation or upon proteasome inhibition. Furthermore, myelin basic protein, an endogenous Schwann cell proteasome substrate, associates with PMP22 aggregates in affected nerves. Together, our data show that in neuropathy nerves, reduced proteasome activity is coupled with the accumulation of ubiquitinated substrates, and the recruitment of proteasomal pathway constituents to aggregates. These results provide novel insights into the mechanism by which altered degradation of Schwann cell proteins may contribute to the pathogenesis of certain PMP22 neuropathies.
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PMID:Impaired proteasome activity and accumulation of ubiquitinated substrates in a hereditary neuropathy model. 1574 70

Proteolytic degradation of autoantigens is of prime importance in current biochemistry and immunology. The most fundamental issue in this field is the functional role of peptides produced when the specificity of hydrolysis changes during the shift from health to disease and from normal state to pathology. The identification of specific peptide fragments in many cases proposes the diagnostic and prognostic criterion in the pathology progression. The aim of this work is comparative study of the degradation peculiarities of one of the main neuroantigen, myelin basic protein by proteases, activated during progress of pathological demyelinating process, and by proteasome of different origin. The comparison of specificity of different studied biocatalysts gives reason to discuss the critical change in the set of myelin basic protein fragments capable to be presented by major histocompatibility complex class I during neurodegeneration, which can promote the progress of autoimmune pathological process.
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PMID:[Functional degradation of myelin basic protein. Proteomic approach]. 2146 Aug 80

The proteasome is a high molecular protein complex whose purpose is specific protein degradation in eukaryotic cells. One of the proteasome functions is to produce peptides, which will then be presented on the outer cell membrane using main histocompatibility complex (MHC) molecules of the first or second class. There are definite reasons to believe that proteasome directly takes part in the specific degradation of myelin basic protein (MBP), which make up to 30% of all proteins in the myelin sheath of neuronal axons. The details of the proteasomal degradation of MBP are still unclear. In this work, the features of specific MBP degradation by proteasome were studied.It was demonstrated that MBP (non-ubiquitinated) is a good substrate for 20S and for the 26S proteasome. This is the first work on detecting the sites of MBP proteolysis by proteasome from brains of SJL/J/J and Balb/C mice's lines. Substantial differences in the degradation pattern of this neuroantigen were found, which could indicate the better presentation MBP parts on MHC molecules in the case of mice predisposed to the development of experimental autoimmune encephalomyelitis.
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PMID:Analysis of myelin basic protein fragmentation by proteasome. 2264 89

Gp96 is the endoplasmic reticulum (ER)-resident molecular chaperone, which is involved in the correction of unfolded proteins, in the activation of proteasome-dependent ER-associated degradation of the misfolded proteins, and in activation of the protein translation that modulates polypeptide traffic into the ER. Furthermore, owing to its peptide chaperone capacity and ability to interact with professional antigen-presenting cells, as well as with growth factors, integrins and Toll-like receptors, it is also endowed with crucial immunological functions acting as a "danger signal" to the innate and adaptive immunity. Considering these properties, in the present study the tissue expression of gp96 was examined during the monophasic and chronic relapsing form of experimental autoimmune encephalomyelitis (CR-EAE), induced in genetically susceptible DA rats by subcutaneous injection of myelin basic protein (MBP) or bovine brain homogenate in complete Freund's adjuvant (CFA). Immunohistochemical analyses were done in periods of attacks and remissions of EAE, and the results were compared with findings in intact rats and those treated only with CFA. The data revealed that the constitutive gp96 expression, found in several neurons and glial cells in the brain and spinal cord of intact animals, significantly diminished during the attacks of CR-EAE. On the contrary, the remission of disease was followed by high upregulation of gp96, mainly in the oligodendrocytes within the white matter, in the neurons of the hippocampal area, as well as in the motoneurons of lumbar spinal cord, suggesting that gp96 might be involved in proteostasis and immune-related pathways linked with the reparative processes in the CNS.
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PMID:Expression pattern of the endoplasmic reticulum stress protein gp96 in monophasic and chronic relapsing form of experimental autoimmune encephalomyelitis in rats. 2323 60

The vast majority of cellular proteins are degraded by the 26S proteasome after their ubiquitination. Here, we report that the major component of the myelin multilayered membrane sheath, myelin basic protein (MBP), is hydrolyzed by the 26S proteasome in a ubiquitin-independent manner both in vitro and in mammalian cells. As a proteasomal substrate, MBP reveals a distinct and physiologically relevant concentration range for ubiquitin-independent proteolysis. Enzymatic deimination prevents hydrolysis of MBP by the proteasome, suggesting that an abnormally basic charge contributes to its susceptibility toward proteasome-mediated degradation. To our knowledge, our data reveal the first case of a pathophysiologically important autoantigen as a ubiquitin-independent substrate of the 26S proteasome.
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PMID:Multiple sclerosis autoantigen myelin basic protein escapes control by ubiquitination during proteasomal degradation. 2473 84

We recently showed that myelin basic protein (MBP) is hydrolyzed by 26S proteasome without ubiquitination. The previously suggested concept of charge-mediated interaction between MBP and the proteasome led us to attempt to compensate or mimic its positive charge to inhibit proteasomal degradation. We demonstrated that negatively charged actin and calmodulin (CaM), as well as basic histone H1.3, inhibit MBP hydrolysis by competing with the proteasome and MBP, respectively, for binding their counterpart. Interestingly, glatiramer acetate (GA), which is used to treat multiple sclerosis (MS) and is structurally similar to MBP, inhibits intracellular and in vitro proteasome-mediated MBP degradation. Therefore, the data reported in this study may be important for myelin biogenesis in both the normal state and pathophysiological conditions.
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PMID:Glatiramer acetate and nanny proteins restrict access of the multiple sclerosis autoantigen myelin basic protein to the 26S proteasome. 2527 31


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