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)

The mechanism of muscle protein catabolism induced by proteolysis-inducing factor, produced by cachexia-inducing murine and human tumours has been studied in vitro using C(2)C(12) myoblasts and myotubes. In both myoblasts and myotubes protein degradation was enhanced by proteolysis-inducing factor after 24 h incubation. In myoblasts this followed a bell-shaped dose-response curve with maximal effects at a proteolysis-inducing factor concentration between 2 and 4 nM, while in myotubes increased protein degradation was seen at all concentrations of proteolysis-inducing factor up to 10 nM, again with a maximum of 4 nM proteolysis-inducing factor. Protein degradation induced by proteolysis-inducing factor was completely attenuated in the presence of cycloheximide (1 microM), suggesting a requirement for new protein synthesis. In both myoblasts and myotubes protein degradation was accompanied by an increased expression of the alpha-type subunits of the 20S proteasome as well as functional activity of the proteasome, as determined by the 'chymotrypsin-like' enzyme activity. There was also an increased expression of the 19S regulatory complex as well as the ubiquitin-conjugating enzyme (E2(14k)), and in myotubes a decrease in myosin expression was seen with increasing concentrations of proteolysis-inducing factor. These results show that proteolysis-inducing factor co-ordinately upregulates both ubiquitin conjugation and proteasome activity in both myoblasts and myotubes and may play an important role in the muscle wasting seen in cancer cachexia.
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PMID:Development of an in-vitro model system to investigate the mechanism of muscle protein catabolism induced by proteolysis-inducing factor. 1208 14

Many aspects of eukaryotic development depend on regulated protein degradation by the ubiquitin-proteasome pathway. This highly conserved pathway promotes covalent attachment of ubiquitin to protein substrates through the sequential action of three enzymes called a ubiquitin-activating enzyme (E1), a ubiquitin-conjugating enzyme (E2), and a ubiquitin-protein ligase (E3). Most ubiquitinated proteins are then targeted for degradation by the 26S proteasome. Recent studies have also shown that the ubiquitin-related protein RUB/Nedd8 and the proteasome-related COP9 signalosome complex cooperate with the ubiquitin-proteasome pathway to promote protein degradation. Most of these components are conserved in all three eukaryotic kingdoms. However, the known targets of the pathway in plants, and the developmental processes they regulate, are specific to the plant kingdom.
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PMID:Plant development: regulation by protein degradation. 1216 44

The androgen receptor (AR) N-terminal domain plays a critical role in androgen-responsive gene regulation. A novel AR N-terminal-interacting protein (ARNIP) was isolated using the yeast two-hybrid system and its interaction with amino acids 11-172 of the normal or corresponding region of the polyglutamine-expanded human AR confirmed by glutathione S-transferase pulldown assays. ARNIP cDNAs cloned from NSC-34 (mouse neuroblastoma/spinal cord) or PC-3 (human prostate adenocarcinoma) mRNA encoded highly homologous 30 kDa (261 amino acids) cysteine-rich proteins with a RING-H2 (C3H2C3 zinc finger) domain; this motif is highly conserved in predicted ARNIP-homologous proteins from several other species. Expression of the approximately 1.7 kb ARNIP mRNA was detected in various tissues by Northern blotting, but was highest in mouse testes, kidney and several neuronal cell lines. In addition, the human ARNIP protein was found to be encoded by nine exons spanning 32 kb on chromosome 4q21. In COS-1 cells, coexpression of ARNIP and AR did not affect AR ligand-binding kinetics, nor did ARNIP act as a coactivator or corepressor in transactivation assays. However, AR N-terminal:C-terminal interaction was reduced in the presence of ARNIP. Intriguingly, ARNIP, and in particular its RING-H2 domain, functioned as a ubiquitin-protein ligase in vitro in the presence of a specific ubiquitin-conjugating enzyme, Ubc4-1. Mutation of a single cysteine residue in the ARNIP RING-H2 domain (Cys145Ala) abolished this E3 ubiquitin ligase activity. Fluorescent protein tagging studies revealed that AR-ARNIP interaction was hormone-independent in COS-1 cells, and suggest that colocalization of both AR and ARNIP to the nucleus upon androgen addition may allow ARNIP to play a role in nuclear processes. Thus, identification of a novel AR-interacting protein with ubiquitin ligase activity will stimulate further investigation into the role of ubiquitination and the ubiquitin-proteasome system in AR-mediated cellular functions.
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PMID:Cloning and characterization of an androgen receptor N-terminal-interacting protein with ubiquitin-protein ligase activity. 1220 Feb 28

Mutation of either the yeast MPS2 or the NDC1 gene leads to identical spindle pole body (SPB) duplication defects: The newly formed SPB is improperly inserted into the nuclear envelope (NE), preventing the cell from forming a bipolar mitotic spindle. We have previously shown that both MPS2 and NDC1 encode integral membrane proteins localized at the SPB. Here we show that CUE1, previously known to have a role in coupling ubiquitin conjugation to ER degradation, is an unusual dosage suppressor of mutations in MPS2 and NDC1. Cue1p has been shown to recruit the soluble ubiquitin-conjugating enzyme, Ubc7p, to the cytoplasmic face of the ER membrane where it can ubiquitinate its substrates and target them for degradation by the proteasome. Both mps2-1 and ndc1-1 are also suppressed by disruption of UBC7 or its partner, UBC6. The Mps2-1p mutant protein level is markedly reduced compared to wild-type Mps2p, and deletion of CUE1 restores the level of Mps2-1p to nearly wild-type levels. Our data indicate that Mps2p may be targeted for degradation by the ER quality control pathway.
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PMID:Mutant membrane protein of the budding yeast spindle pole body is targeted to the endoplasmic reticulum degradation pathway. 1239 72

Genes transcribed by RNA polymerase II are silenced when introduced near the mat2 or mat3 mating-type loci of the fission yeast Schizosaccharomyces pombe. Silencing is mediated by a number of gene products and cis-acting elements. We report here the finding of novel trans-acting factors identified in a screen for high-copy-number disruptors of silencing. Expression of cDNAs encoding the putative E2 ubiquitin-conjugating enzymes UbcP3, Ubc15 (ubiquitin-conjugating enzyme), or Rhp6 (Rad homolog pombe) from the strong nmt1 promoter derepressed the silent mating-type loci mat2 and mat3 and reporter genes inserted nearby. Deletion of rhp6 slightly derepressed an ade6 reporter gene placed in the mating-type region, whereas disruption of ubcP3 or ubc15 had no obvious effect on silencing. Rhp18 is the S. pombe homolog of Saccharomyces cerevisiae Rad18p, a DNA-binding protein that physically interacts with Rad6p. Rhp18 was not required for the derepression observed when UbcP3, Ubc15, or Rhp6 was overproduced. Overexpressing Rhp6 active-site mutants showed that the ubiquitin-conjugating activity of Rhp6 is essential for disruption of silencing. However, high dosage of UbcP3, Ubc15, or Rhp6 was not suppressed by a mutation in the 26S proteasome, suggesting that loss of silencing is not due to an increased degradation of silencing factors but rather to the posttranslational modification of proteins by ubiquitination. We discuss the implications of these results for the possible modes of action of UbcP3, Ubc15, and Rhp6.
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PMID:The fission yeast ubiquitin-conjugating enzymes UbcP3, Ubc15, and Rhp6 affect transcriptional silencing of the mating-type region. 1245 9

Our aim was to determine the molecular targets involved in the antiproliferative effects of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), in a normal murine mammary epithelial cell line, HC11. Among the early response genes analyzed, c-myc, junB, junD, c-jun, c-fos, fosB, fra, as well as max, mad1-4, sin3, only c-jun and fra-2 mRNAs were up-regulated after 1,25(OH)(2)D(3) exposure. Cyclin C was reduced and cyclin A2 and E were slightly enhanced; however, cyclins D1, D3, B1, B2, F, G1, G2, I and H, as well as TGF beta 1, TGF beta 3, T beta RI and T beta RII transcripts were not modulated by 1,25(OH)(2)D(3). Although p27(KIP1) protein content was unchanged, enhancement of p21(WAF1/CIP1) low basal levels in cell extracts and IGFBP-3 abundance on the culture medium was detected after 1,25(OH)(2)D(3) induction. Using differential display analysis, we identified eight down-modulated clones in exposed cells: 26S proteasome non-ATPase subunit Pad1, ubiquitin-conjugating enzyme Ube2i, extracellular proteinase inhibitor Expi or Wdnm1, cytochrome-c oxidase Cox7c, microtubule-associated protein-1 light chain-3 (Map1lc3), nascent-associated complex alpha Naca, transforming acidic coiled-coil Tacc3, stearoyl-CoA desaturase (Scd), keratin 6 alpha, and 1 up-regulated, fork head transcription factor Hfh-1L. Hence, the antiproliferative effect of 1,25(OH)(2)D(3) seems associated to enhancement of c-jun, Fra-2, IGFBP3 and p21(WAF1/CIP1). Decreased Pad1 and Ube2i might account for increased stability of cell cycle inhibitory proteins while reduced Wdnm1, Tacc3 and Scd might be secondary to accumulation of cells in G0/G1 phase.
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PMID:Molecular targets of 1,25(OH)2D3 in HC11 normal mouse mammary cell line. 1264 25

Disruption of Ube2b in the mouse has revealed that the regular and symmetric organization of the fibrous sheath of the sperm flagella is dependent on expression of the ubiquitin-conjugating enzyme UBE2B. These data could cast light on how a component of the ubiquitin-proteasome pathway participates in the assembly of flagellar periaxonemal structures. Data in the literature support the notion of involvement of ubiquitin-proteasome pathways in the assembly of cytoskeletal components in somatic cells. This review attempts to integrate recent knowledge regarding flagellar components that could be related to proteasome components and, therefore, could be targets of UBE2B in the spermatid. An attempt is made to characterize the human flagellar anomalies of infertile patients, which are the closest to those of Ube2b-deficient mice. These new insights regarding the assembly of mammalian sperm flagella provide a basis for studying the ontogenesis of flagellar accessory structures and suggest leads for medical and genetic investigations.
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PMID:New insights into the assembly of the periaxonemal structures in mammalian spermatozoa. 1267 59

Cell cycle events are regulated by sequential activation and inactivation of Cdk kinases. Mitotic exit is accomplished by the inactivation of mitotic Cdk kinase, which is mainly achieved by degradation of cyclins. The ubiquitin-proteasome system is involved in this process, requiring APC/C (anaphase-promoting complex/cyclosome) as a ubiquitin ligase. In Xenopus and clam oocytes, the ubiquitin-conjugating enzymes that function with APC/C have been identified as two proteins, UBC4 and UBCx/E2-C. Previously we reported that the fission yeast ubiquitin-conjugating enzyme UbcP4/Ubc11, a homologue of UBCx/E2-C, is required for mitotic transition. Here we show that the other fission yeast ubiquitin-conjugating enzyme, UbcP1/Ubc4, which is homologous to UBC4, is also required for mitotic transition in the same manner as UbcP4/Ubc11. Both ubiquitin-conjugating enzymes are essential for cell division and directly required for the degradation of mitotic cyclin Cdc13. They function nonredundantly in the ubiquitination of CDC13 because a defect in ubcP1/ubc4+ cannot be suppressed by high expression of UbcP4/Ubc11 and a defect in ubcP4/ubc11+ cannot be suppressed by high expression of UbcP1/Ubc4. In vivo analysis of the ubiquitinated state of Cdc13 shows that the ubiquitin chains on Cdc13 were short in ubcP1/ubc4 mutant cells while ubiquitinated Cdc13 was totally reduced in ubcP4/ubc11 mutant cells. Taken together, these results indicate that the two ubiquitin-conjugating enzymes play distinct and essential roles in the degradation of mitotic cyclin Cdc13, with the UbcP4/Ubc11-pathway initiating ubiquitination of Cdc13 and the UbcP1/Ubc4-pathway elongating the short ubiquitin chains on Cdc13.
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PMID:Two ubiquitin-conjugating enzymes, UbcP1/Ubc4 and UbcP4/Ubc11, have distinct functions for ubiquitination of mitotic cyclin. 1272 8

Hox proteins are transcription factors involved in controlling axial patterning, leukaemias and hereditary malformations. Here, we show that HOXC10 oscillates in abundance during the cell cycle, being targeted for degradation early in mitosis by the ubiquitin-dependent proteasome pathway. Among abdominal-B subfamily members, the mitotic proteolysis of HOXC10 appears unique, since the levels of the paralogous HOXD10 and the related homeoprotein HOXC13 are constant throughout the cell cycle. When two destruction box motifs (D-box) are mutated, HOXC10 is stabilized and cells accumulate in metaphase. HOXC10 appears to be a new prometaphase target of the anaphase-promoting complex (APC), since its degradation coincides with cyclin A destruction and is suppressed by expression of a dominant-negative form of UbcH10, an APC-associated ubiquitin-conjugating enzyme. Moreover, HOXC10 co-immunoprecipitates the APC subunit CDC27, and its in vitro degradation is reduced in APC-depleted extracts or by competition with the APC substrate cyclin A. These data imply that HOXC10 is a homeoprotein with the potential to influence mitotic progression, and might provide a link between developmental regulation and cell cycle control.
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PMID:Early mitotic degradation of the homeoprotein HOXC10 is potentially linked to cell cycle progression. 1285 86

Ubiquitin-dependent proteolysis by the 26S proteasome plays a pivotal role in cell cycle progression as well as in tumorigenesis. In this pathway, ubiquitin-conjugating enzyme (E2), together with ubiquitin ligase (E3), transfers ubiquitin to the specific substrate protein(s); however, little is known about the potential contribution of E2 to tumorigenesis. In this study, we examined the expression levels of 17 E2 genes in 25 different human normal tissues and 24 human cancerous cell lines by using a quantitative real-time reverse transcription-PCR. Among the E2 gene family, the expression level of UbcH10 was extremely low in many of the normal tissues but prominent in the majority of cancerous cell lines. Intriguingly, UbcH10 was expressed at high levels in primary tumors derived from the lung, stomach, uterus, and bladder as compared with their corresponding normal tissues, suggesting that UbcH10 is involved in tumorigenesis or progression of the tumor. To further investigate a possible contribution of UbcH10 to malignant transformation and tumor cell proliferation, NIH3T3 cells were transfected with the expression plasmid encoding UbcH10, and stable transfectants were subsequently established. UbcH10-overexpressing cells exhibited an increased incorporation of bromodeoxyuridine, an enhanced growth rate, an increase in saturation density, and a promotion of colony formation in soft agar medium as compared with parental NIH3T3 cells and the control transfectants. Collectively, our present results provide the first evidence that UbcH10 is highly expressed in various human primary tumors and that UbcH10 has an ability to promote cell growth and malignant transformation.
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PMID:UbcH10 is the cancer-related E2 ubiquitin-conjugating enzyme. 1287 22


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