Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P62988 (Ubiquitin)
 4,326 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been previously reported that Bryostatin 1 (Bryo1) induces differentiation of the human acute lymphoblastic leukemia (ALL) cell line, Reh, to a monocytoid B-cell stage. In this study we demonstrate that a novel protein, ubiquitin COOH-terminal hydrolase (UCH-L1), is associated with this differentiation. Reh cells were treated with 200 nmol/l of Bryo1 for 72 h and analyzed for changes in morphology, surface immunophenotype, acid phosphatase and terminal deoxynucleotidyl transferase. Protein patterns of the parent and differentiated cells, by two-dimensional polyacrylamide gel electrophoresis (2D PAGE), were studied. Bryo1-treated cells expressed morphologic, phenotypic and enzymatic features of the monocytoid B-cell stage. The UCH-L1 enzyme (MW-pl 34-5.3) was detected by 2 D PAGE in the differentiated, but not in parent cells. The presence of UCH-L1 in the Bryo1-treated cells was further confirmed by immunoblotting of 2 D PAGE using UCH-L1 polyclonal antibody. Ubiquitin expression was studied in parent and Bryo1-treated cells and was compared with 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated cells. Both agents, TPA and Bryo1, increased the level of ubiquitin expression as detected by flow cytometry. Sodium borohydride, an inhibitor of UCH-L1, inhibited the Bryo1-induced differentiating effect on Reh cells. To date, the mechanism by which Bryo1, exerts its B-cell differentiating effect is not fully understood. This study shows that UCH-L1 expression may play a major role in Bryo1-induced differentiation in pre-B-ALL.
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PMID:Bryostatin 1 induces ubiquitin COOH-terminal hydrolase in acute lymphoblastic leukemia cells. 925 84

The experimentally induced cryptorchid mouse model is useful for elucidating the in vivo molecular mechanism of germ cell apoptosis. Apoptosis, in general, is thought to be partly regulated by the ubiquitin-proteasome system. Here, we analyzed the function of two closely related members of the ubiquitin C-terminal hydrolase (UCH) family in testicular germ cell apoptosis experimentally induced by cryptorchidism. The two enzymes, UCH-L1 and UCH-L3, deubiquitinate ubiquitin-protein conjugates and control the cellular balance of ubiquitin. The testes of gracile axonal dystrophy (gad) mice, which lack UCH-L1, were resistant to cryptorchid stress-related injury and had reduced ubiquitin levels. The level of both anti-apoptotic (Bcl-2 family and XIAP) and prosurvival (pCREB and BDNF) proteins was significantly higher in gad mice after cryptorchid stress. In contrast, Uchl3 knockout mice showed profound testicular atrophy and apoptotic germ cell loss after cryptorchid injury. Ubiquitin level was not significantly different between wild-type and Uchl3 knockout mice, whereas the levels of Nedd8 and the apoptotic proteins p53, Bax, and caspase3 were elevated in Uchl3 knockout mice. These results demonstrate that UCH-L1 and UCH-L3 function differentially to regulate the cellular levels of anti-apoptotic, prosurvival, and apoptotic proteins during testicular germ cell apoptosis.
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PMID:Two closely related ubiquitin C-terminal hydrolase isozymes function as reciprocal modulators of germ cell apoptosis in cryptorchid testis. 1546

During aging, the production of free radicals increases. This can result in damage to protein, the accumulation of which is characteristic of the aging process. This questions the efficacy of proteolytic systems. Among these systems, the proteasome and the adenosine triphosphate-ubiquitin-dependent pathway have been shown to play an important role in the elimination of abnormal proteins. There are two major steps in the ubiquitin-proteasome pathway: the conjugation of a polyubiquitin degradation signal to the substrate and the subsequent degradation of the tagged protein by the 26S proteasome. The 26S proteasome is build-up from the 20S proteasome, which is a cylinder-shaped multimeric complex, and two additional 19S complexes. The 20S proteasome can also bind to 11S regulator and is then implicated in antigen presentation. These regulators confer a high adaptability on proteasome. With advancing age, predisposition to neurodegenerative diseases increases. These diseases are also characterized by protein aggregation. Several findings such as the presence of ubiquinated proteins, usually broken down by proteasomes, and genetic anomalies involving the ubiquitin-proteasome system (parkin, UCH-L1) suggest a link between the ubiquitin-proteasome pathway and the genesis of these diseases.
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PMID:Linkage between the proteasome pathway and neurodegenerative diseases and aging. 1547 27

Ubiquitin specific proteases (USPs) regulate the production and recycling of ubiquitin and are thereby critically involved in the control of cell growth, differentiation, and apoptosis. Increasing evidence implicates deregulation of USPs in malignant transformation but there is very little information on the overall and specific activity of USPs in normal and tumor tissues. We have used a chemistry-based functional proteomics approach to profile the activities of individual USPs in biopsies of human papillomavirus (HPV) carrying cervical carcinoma and adjacent normal tissue. To assess the contribution of HPV proteins, USP activity was also compared in HPV positive and negative cervical carcinoma cell lines and HPV E6/E7 immortalized human keratinocytes. The activity of the C-terminal hydrolases UCH-L3 and UCH37 was upregulated in the majority of tumor tissues compared to the adjacent normal tissues. UCH-L1 activity was lower in a significant proportion of the tumors but to a less extent in advanced tumors. In accordance with the relatively low UCH-L1 activity in tumor biopsies, UCH-L1 was detected only in one out of eight cervical carcinoma lines. UCH-L1, UCH-L3, USP7, and USP9X activity was upregulated following HPV E6/E7 immortalization of keratinocytes, suggesting a role of these enzymes in growth transformation.
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PMID:Activity profiling of deubiquitinating enzymes in cervical carcinoma biopsies and cell lines. 1640 89

The ubiquitin-proteasome pathway is crucial for protein turnover. Part of the pathway involves deubiquitination, which is carried out by cystein proteases known as ubiquitin COOH-terminal hydrolases. The isoform Uch-L1 was found to be present in large amounts in rat islets by immunostaining, Western blot analysis, and RT-PCR. Culturing islets in high glucose concentrations (16.7 mmol/l) for 24 h led to decreased gene expression. Exposure to chronic hyperglycemia following 90% partial pancreatectomy also led to reduced Uch-L1 expression. Expression of other members of the ubiquitin-proteasome pathway studied after culturing islets at high glucose concentrations revealed little change except for modest declines in parkin, human ubiquitin-conjugating enzyme 5 (UbcH5), and beta-TRCP (transducin repeat-containing protein). With the pancreatectomy model, expression of polyubiquitin-B and c-Cbl were increased and E6-associated protein was reduced. Further insight about the proteasome pathway was obtained with the proteasome inhibitor lactacystin, which in short-term 2-h experiments enhanced glucose-induced insulin secretion. An important role for the ubiquitin-proteasome pathways in beta-cells is suggested by the findings that changes in glucose concentration influence expression of genes in the pathway and that blockade of the proteasome degradation machinery enhances glucose-stimulated insulin secretion.
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PMID:Evidence for a role of the ubiquitin-proteasome pathway in pancreatic islets. 1664 76

Ubiquitin (Ub) carboxy terminal hydrolase (UCH)-L1 and UCH-L3 are two of the deubiquitinating enzymes expressed in the brain. Both gad mice, which lack UCH-L1 expression and Uchl3 knockout mice exhibit neurodegeneration, although at distinct areas. These phenotypes indicate the importance of UCH-L1 and UCH-L3 in the regulation of the central nervous system. However, molecular substrates and the molecular regulators of UCH-L1 and UCH-L3 remain poorly identified. Here we show that Ub dimers interact non-covalently with UCH-L3 in vitro and in cells. These interactions were not observed with UCH-L1 in cells. In vitro, K48-linked Ub dimers pronouncedly inhibited the hydrolase activity of UCH-L3, while mono-Ub, a previously identified interacting protein, inhibited the hydrolase activity of UCH-L1. These results indicate that mono-Ub and Ub dimers may regulate the enzymatic functions of UCH-L1 and UCH-L3, respectively, in vivo.
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PMID:Ubiquitin dimers control the hydrolase activity of UCH-L3. 1915 70

Ubiquitin (Ub) carboxyl-terminal hydrolase L1 (UCH-L1) has dual functions, such as hydrolase activity on the chemical bonds formed by the C-terminal Gly of Ub and dimerization-dependent ubiquitin ligase activity. Accumulating evidence suggests that dual activities of UCH-L1 were intimately associated with Parkinson's diseases (PD) and cancer. However, the molecular mechanism that regulates UCH-L1 enzymatic activity has not yet been fully elucidated. The serine protease high temperature requirement A2 (HtrA2), a PD-associated gene, is important in regulating cell survival as well as apoptosis. Using in vitro and in vivo cleavage assays, we have demonstrated that UCH-L1 is a natural substrate for the serine protease HtrA2 in the apoptotic pathway. Notably, we show that released, cytosolic HtrA2 decreases UCH-L1 protein level and its hydrolase activity through HtrA2-mediated cleavage of UCH-L1 under apoptotic conditions. These findings suggest that the HtrA2-mediated cleavage of UCH-L1 may play important roles in regulating the fine balance between cell growth and cell death.
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PMID:The serine protease HtrA2 cleaves UCH-L1 and inhibits its hydrolase activity: implication in the UCH-L1-mediated cell death. 2200 20

UCH-L1 (ubiquitin carboxyl terminal hydrolase L1) is well known as an enzyme that hydrolyzes polyubiquitin at its C-terminal to release ubiquitin monomers. Although the overexpression of UCH-L1 inhibits proteasome activity in cultured cells, its biological significance in living organisms has not been clarified in detail. Here, we utilized Drosophila as a model system to examine the effects of the overexpression of dUCH, a Drosophila homologue of UCH-L1, on development. Overexpression in the eye imaginal discs induced a rough eye phenotype in the adult, at least partly resulting from the induction of caspase-dependent apoptosis followed by compensatory proliferation. Genetic crosses with enhancer trap lines marking the photoreceptor cells also revealed that the overexpression of dUCH specifically impaired R7 photoreceptor cell differentiation with a reduction in activated extracellular-signal-regulated kinase signals. Furthermore, the dUCH-induced rough eye phenotype was rescued by co-expression of the sevenless gene or the Draf gene, a downstream component of the mitogen-activated protein kinase (MAPK) cascade. These results indicate that the overexpression of dUCH impairs R7 photoreceptor cell differentiation by down-regulating the MAPK pathway. Interestingly, this process appears to be independent of its pro-apoptotic function.
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PMID:Overexpression of ubiquitin carboxyl terminal hydrolase impairs multiple pathways during eye development in Drosophila melanogaster. 2252 25

The BH3-only protein NOXA represents one of the critical mediators of DNA-damage-induced cell death. In particular, its involvement in cellular responses to cancer chemotherapy is increasingly evident. Here, we identify a strategy of cancer cells to escape genotoxic chemotherapy by increasing proteasomal degradation of NOXA. We show that the deubiquitylating enzyme UCH-L1 is a key regulator of NOXA turnover, which protects NOXA from proteasomal degradation by removing Lys(48)-linked polyubiquitin chains. In the majority of tumors from patients with melanoma or colorectal cancer suffering from high rates of chemoresistance, NOXA fails to accumulate because UCH-L1 expression is epigenetically silenced. Whereas UCH-L1/NOXA-positive tumor samples exhibit increased sensitivity to genotoxic chemotherapy, downregulation of UCH-L1 or inhibition of its deubiquitylase activity resulted in reduced NOXA stability and resistance to genotoxic chemotherapy in both human and C. elegans cells. Our data identify the UCH-L1/NOXA interaction as a therapeutic target for overcoming cancer chemoresistance.
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PMID:Ubiquitin C-terminal hydrolase-L1 potentiates cancer chemosensitivity by stabilizing NOXA. 2349 48

Ubiquitin proteasome system (UPS) determines the timing and extent of protein turnover in cells, and it is one of the most strictly controlled cellular mechanisms. Lack of proper control over UPS is attributed to both cancer and to neurodegenerative diseases, yet in different context and direction. Cancerous cells have altered cellular metabolisms, uncontrolled cellular division, and increased proteasome activity. The specialized function prevent neurons from undergoing cellular division but allow them to extend an axon over long distances, establish connections, and to form stable neuronal circuitries. Neurons heavily depend on the proper function of the proteasome and the UPS for their proper function. Reduction of UPS function in vulnerable neurons results in protein aggregation, increased ER stress, and cell death. Identification of compounds that selectively block proteasome function in distinct set of malignancies added momentum to drug discovery efforts, and deubiquitinases (DUBs) gained much attention. This review will focus on ubiquitin carboxy-terminal hydrolase L1 (UCHL1), a DUB that is attributed to both cancer and neurodegeneration. The potential of developing effective treatment strategies for two major health problems by controlling the function of UPS opens up new avenues for innovative approaches and therapeutic interventions.
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PMID:Could dysregulation of UPS be a common underlying mechanism for cancer and neurodegeneration? Lessons from UCHL1. 2369 85


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