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)

Alizapride (ALZ) is a new benzamide derivative with promising antiemetic activity. In the present study, high-dose ALZ (16 mg/kg) alone or in combination with dexamethasone (DXM, 40 mg) was compared to a combination of DXM (40 mg) and metoclopramide (MCP, 4 mg/kg) in a randomized cross-over trial conducted on 21 out-patients at high emetic risk after moderate-dose cisplatin. All but 3 patients completed the planned cross-over trial for a total of 60 evaluable courses. The patients completed a self assessment questionnaire evaluating the severity and duration of both nausea and vomiting, the toxicity, as well as their subjective opinion of the antiemetic trial. At the dose and schedule employed, ALZ alone or in combination with DXM provided not only a significantly lower rate of complete protection against nausea and vomiting (0 and 4.8%) than MCP + DXM (28.6%) but was also less effective in reducing the number of vomiting episodes and the duration of the vomiting. In addition, the MCP - DXM regimen was the most frequently preferred. Except for one case of orthostatic hypotension following ALZ, benzamide-induced toxicity was mild, whereas that related to DXM was negligible. The results of this study suggest that high-dose ALZ gives no advantage compared to MCP in patients at high risk for emesis after moderate-dose cisplatin.
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PMID:Alizapride alone or alizapride-dexamethasone compared with metoclopramide-dexamethasone in patients at high risk of acute emesis after cisplatin. A randomized cross-over study. 195 93

Muscle wasting in catabolic conditions results from activation of the ubiquitin-proteasome proteolytic pathway by a process that requires glucocorticoids and is generally associated with increased levels of mRNAs encoding components of this proteolytic system. In L6 muscle cells, dexamethasone stimulates proteolysis and increases the amount of the proteasome C3 subunit protein by augmenting its transcription. Transfection studies with human C3 promoter-luciferase reporter genes and electrophoretic mobility shift assays revealed that a NF-kappaB.protein complex containing Rel A is abundant in L6 muscle cell nuclei. Glucocorticoids stimulate C3 subunit expression by antagonizing the interaction of this NF-kappaB protein with an NF-kappaB response element in the C3 subunit promoter region. Dexamethasone also increased the cytosolic amounts of the NF-kappaB p65 subunit and the IkappaBalpha inhibitor proteins in L6 cells. Incubation of L6 cells with a cytokine mixture not only increased the amount of activated NF-kappaB but also decreased C3 promoter activity and lowered endogenous C3 subunit mRNA. Thus, NF-kappaB is a repressor of C3 proteasome subunit transcription in muscle cells, and glucocorticoids stimulate C3 subunit expression by opposing this suppressor action.
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PMID:Glucocorticoids induce proteasome C3 subunit expression in L6 muscle cells by opposing the suppression of its transcription by NF-kappa B. 1086 22

The glucocorticoid receptor (GR) and the tumor suppressor p53 mediate different stress responses. We have studied the mechanism of their mutual inhibition in normal endothelial cells (HUVEC) in response to hypoxia, a physiological stress, and mitomycin C, which damages DNA. Dexamethasone (Dex) stimulates the degradation of endogenous GR and p53 by the proteasome pathway in HUVEC under hypoxia and mitomycin C treatments, and also in hepatoma cells (HepG2) under normoxia. Dex inhibits the functions of p53 (apoptosis, Bax, and p21(WAF1/CIP1) expression) and GR (PEPCK and G-6-Pase expression). Endogenous p53 and GR form a ligand-dependent trimeric complex with Hdm2 in the cytoplasm. Disruption of the p53-HDM2 interaction prevents Dex-induced ubiquitylation of GR and p53. The ubiquitylation of GR requires p53, the interaction of p53 with Hdm2, and E3 ligase activity of Hdm2. These results provide a mechanistic basis for GR and p53 acting as opposing forces in the decision between cell death and survival.
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PMID:Ligand-dependent interaction of the glucocorticoid receptor with p53 enhances their degradation by Hdm2. 1156 47

Glucocorticoid-sensitive alkaline proteases are localized in the nuclear and mitochondrial fractions of rat thymocytes. Dexamethasone load increased alkaline protease activity in the nuclear fraction and decreased or even eliminated it in the mitochondrial fraction. The inhibitory analysis showed that SH groups and disulfide bonds play a crucial role in the functioning of glucocorticoid-activated nuclear alkaline protease. Hence, this enzyme can be assigned to as cysteine proteases. Mitochondrial alkaline protease is a serine hydrolase, although it does not belong to the class of trypsin- or chymotrypsin-like enzymes. The role of alkaline proteases in apoptotic death of thymocytes is discussed.
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PMID:Mitochondrial and nuclear glucocorticoid-sensitive alkaline proteases in thymocytes. 1168 37

The muscle protein catabolism present in rats with insulin-dependent diabetes and other catabolic conditions is generally associated with increased glucocorticoid production and mRNAs encoding components of the ubiquitin-proteasome system. The mechanisms that increase ubiquitin (UbC) expression have not been identified. We studied the regulation of UbC expression in L6 muscle cells because dexamethasone stimulates the transcription of this gene and others encoding components of the ubiquitin-proteasome pathway. Results of in vivo genomic DNA footprinting experiments indicate that a protein(s) binds to Sp1 sites approximately 50 bp upstream from the UbC transcription start site; dexamethasone changes the methylation pattern at these sites. Sp1 binds to DNA probes corresponding to the rat or human UbC promoter, and treating cells with dexamethasone increases this binding. Deletion and mutation analyses of the rat and human UbC promoters are consistent with an important role of Sp1 in UbC induction by glucocorticoids. Dexamethasone-induced ubiquitin expression is blocked by mithramycin, an inhibitor of Sp1 binding. UO126, a pharmacologic inhibitor of MEK1, also blocks UbC transcriptional activation by dexamethasone; L6 cells transfected to express constitutively active MEK1 exhibit increased UbC promoter activity. Thus, glucocorticoids increase UbC expression in muscle cells by a novel transcriptional mechanism involving Sp1 and MEK1.
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PMID:Ubiquitin (UbC) expression in muscle cells is increased by glucocorticoids through a mechanism involving Sp1 and MEK1. 1187 50

Corticosteroids can influence brain function, and glucocorticoid hormone receptors (GRs) are present in brain tissue. We observed that GR and also mineralocorticoid receptor (MR) are expressed by embryonic rat neural stem cells (NSCs). NSCs in developing ventricular epithelium were positive for GR. Stimulation of cultured NSCs with the specific receptor ligands dexamethasone and corticosterone reduced cell proliferation, shown by 5'-bromo-2-deoxy-uridine labeling. The effect of the hormones was dose dependent and inhibited by the GR blocker mifepristone but not by spironolactone, blocking MR. Dexamethasone inhibited the cell cycle by decreasing the levels of cyclin D1 in NSCs. The hormone-induced decline was inhibited by MG132 (benzyloxycarbonyl-leucyl-leucyl-leucinal), showing an involvement of the ubiquitin proteasome system, In keeping with this, dexamethasone increased the ubiquitination of cyclin D1. In embryonic brain, dexamethasone inhibited cell proliferation of NSCs. This demonstrates that embryonic NSCs are critically influenced by glucocorticoids, which can have long-term effects in the brain.
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PMID:Glucocorticoid hormones decrease proliferation of embryonic neural stem cells through ubiquitin-mediated degradation of cyclin D1. 1670 92

Glucocorticoids have long been used as first-line immunosuppressants, although their precise mechanism of action has not been fully elucidated yet. This study evaluated the gene and protein expression of monocyte chemoattractant protein-1 (MCP-1), and its relationship with interleukin-12 and interleukin-10 synthesis, in human monocyte-derived dendritic cells exposed to dexamethasone. Dendritic cells were differentiated in the presence or in the absence of dexamethasone and then activated by IFN-gamma+soluble CD40 ligand; the gene and protein expression of target cytokines was measured by real-time PCR and ELISA, respectively. Our results showed that dexamethasone-primed mature dendritic cells expressed low levels of interleukin-12, and, at the opposite, high levels of interleukin-10 and MCP-1. Transfection experiments confirmed the ability of dexamethasone to activate MCP-1 gene promoter. Dexamethasone increased also MCP-2, but not MCP-3 synthesis, and the gene expression of CC chemokine receptor-2 by mature dendritic cells. The addition of anti-MCP-1 blocking antibody depressed MCP-1 release, and increased interleukin-12 production in dexamethasone-treated dendritic cells, thus demonstrating that interleukin-12 downregulation is largely dependent on MCP-1 overexpression. Our findings suggest that the induction of MCP expression in human dendritic cells by dexamethasone, and the amplification of cell response via the upregulation of the chemokine cognate receptor, may be critical to inhibit type 1 T-helper-biased immune response and, possibly, to favor type 2 T-helper-skewed response.
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PMID:Dexamethasone modulates interleukin-12 production by inducing monocyte chemoattractant protein-1 in human dendritic cells. 1770 May 11

The ubiquitin-proteasome system plays an important role in the degradation of myofibrillar proteins that occurs in muscle wasting. Many studies have demonstrated the importance of enzymes mediating conjugation of ubiquitin. However, little is known about the role of deubiquitinating enzymes. We previously showed that the USP19-deubiquitinating enzyme is induced in atrophying skeletal muscle (Combaret L, Adegoke OA, Bedard N, Baracos V, Attaix D, Wing SS. Am J Physiol Endocrinol Metab 288: E693-E700, 2005). To further explore the role of USP19, we used small interfering RNA (siRNA) in L6 muscle cells. Lowering USP19 by 70-90% in myotubes resulted in a 20% decrease in the rate of proteolysis and an 18% decrease in the rate of protein synthesis, with no net change in protein content. Despite the decrease in overall synthesis, there were approximately 1.5-fold increases in protein levels of myosin heavy chain (MHC), actin, and troponin T and a approximately 2.5-fold increase in tropomyosin. USP19 depletion also increased MHC and tropomyosin mRNA levels, suggesting that this effect is due to increased transcription. Consistent with this, USP19 depletion increased myogenin protein and mRNA levels approximately twofold. Lowering myogenin using siRNA prevented the increase in MHC and tropomyosin upon USP19 depletion, indicating that myogenin mediated the increase in myofibrillar proteins. Dexamethasone treatment lowered MHC and increased USP19. Depletion of USP19 reversed the dexamethasone suppression of MHC. These studies demonstrate that USP19 modulates transcription of major myofibrillar proteins and indicate that the ubiquitin system not only mediates the increased protein breakdown but is also involved in the decreased protein synthesis in atrophying skeletal muscle.
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PMID:USP19-deubiquitinating enzyme regulates levels of major myofibrillar proteins in L6 muscle cells. 1977 79

Dexamethasone (Dex), a synthetic glucocorticoid, has a clinical adverse effect on bone acquisition and metabolism at pharmacological doses. To investigate the underlying mechanisms of Dex induced bone loss, we employed calvaria derived mesenchymal progenitor cells (MPCs) to examine the effects of Dex on their osteoblast lineage commitment and mineralization function. MPCs were cultured up to 28 days in the presence or absence of pharmacological doses of Dex. Alkaline phosphatase (ALP) and von Kossa histochemical staining showed that Dex decreased ALP activity and mineralized nodule formation. In addition, Dex treatment led to inhibition of cell proliferation and a decrease of cell numbers as assessed by BrdU incorporation and MTT methods, while it increased apoptosis as shown by flow cytometry of annexin V-stained cells. These effects were associated with a marked reduction of secreted IGF-I levels as indicated by ELISA quantification, raising the possibility that Dex decreased proliferation and promoted apoptosis of MPCs through the inhibition of IGF-I secretion. To further define the effect of Dex on osteoblast lineage commitment, Runx2 and Osx, the key transcription regulators of osteogenesis, were determined at both mRNA and protein levels. Interestingly, no effects were observed on mRNA and protein expression of Osx, while the mRNA and protein levels of Runx2 were inhibited by Dex treatment. Taken together, the inhibition of the expression of IGF-I and Runx2 by Dex in this in vitro system may account for the impaired MCP proliferation, osteoblastic differentiation and mineralized matrix deposition. These findings and the in vitro MCP system developed will facilitate further mechanistic studies of glucocorticoid induced bone loss.
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PMID:Inhibitory effects of pharmacological doses of dexamethasone on mineralization of mesenchymal progenitor cells in vitro. 1994 71

Glucocorticoid receptors (GRs) are members of a highly conserved family of ligand dependent transcription factors which following hormone binding undergo homologous down-regulation reducing the levels of receptor protein. This decline in human GR (hGR) is due in part to a decrease in protein receptor stability that may limit cellular responsiveness to ligand. To examine the role of the proteasome protein degradation pathway in steroid-dependent hGR responsiveness, we utilized the proteasomal inhibitors MG-132, beta-lactone, and epoxomicin. HeLa cells and COS cells were treated with proteasome inhibitors in the presence of the GR agonist dexamethasone (Dex), or were pretreated with proteasomal inhibitor and then Dex. Dexamethasone induced glucocorticoid responsive reporter activity significantly over untreated controls, whereas cells treated with proteasomal inhibitors and Dex together showed 2-3-fold increase in activity. Protein sequence analysis of the hGR protein identified several candidate protein degradation motifs including a PEST element. Mutagenesis of this element at lysine 419 was done and mutant K419A hGR failed to undergo ligand dependent down-regulation. Mutant K419A hGR displayed 2-3-fold greater glucocorticoid responsive reporter activity in the presence of Dex than wild type hGR. These differences in transcriptional activity were not due to altered subcellular localization, since when the mutant K419A hGR was fused with the green fluorescent protein (GFP) it was found to move in and out of the nucleus similarly to wild type hGR. Together these results suggest that the proteasome and the identified PEST degradation motif limit steroid-dependent human glucocorticoid receptor signaling.
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PMID:Lysine 419 targets human glucocorticoid receptor for proteasomal degradation. 2061 82


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