Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 26S proteasome, which is a multi-subunit protease with specificity for substrate proteins that are postranslationally modified by ubiquitination, has been implicated in acrosomal function and sperm-zona pellucida (ZP) penetration during mammalian fertilization. Ubiquitin C-terminal hydrolases (UCHs) are responsible for the removal of polyubiquitin chains during substrate priming for proteasomal proteolysis. The inhibition of deubiquitination increases the rate of proteasomal proteolysis. Consequently, we have hypothesized that inhibition of sperm acrosome-borne UCHs increases the rate of sperm-ZP penetration and polyspermy during porcine in vitro fertilization (IVF). Ubiquitin aldehyde (UA), which is a specific nonpermeating UCH inhibitor, significantly (P < 0.05) increased polyspermy during porcine IVF and reduced (P < 0.05) UCH enzymatic activity measured in motile boar spermatozoa using a specific fluorometric UCH substrate, ubiquitin-AMC. Antibodies against two closely related UCHs, UCHL1 and UCHL3, detected these UCHs in the oocyte cortex and on the sperm acrosome, respectively, and increased the rate of polyspermy during IVF, consistent with the UA-induced polyspermy surge. In the oocyte, UCHL3 was primarily associated with the meiotic spindle. Sperm-borne UCHL3 was localized to the acrosomal surface and coimmunoprecipitated with a peripheral acrosomal membrane protein, spermadhesin AQN1. Recombinant UCHs, UCHL3, and isopeptidase T reduced polyspermy when added to the fertilization medium. UCHL1 was detected in the oocyte cortex but not on the sperm surface, and was partially degraded 6-8 h after fertilization. Enucleated oocyte-somatic cell electrofusion caused polarized redistribution of cortical UCHL1. We conclude that sperm-acrosomal UCHs are involved in sperm-ZP interactions and antipolyspermy defense. Modulation of UCH activity could facilitate the management of polyspermy during IVF and provide insights into male infertility.
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PMID:Ubiquitin C-terminal hydrolase-activity is involved in sperm acrosomal function and anti-polyspermy defense during porcine fertilization. 1767 Dec 68

We used comparative proteomic techniques to identify aging-related brain proteins in normal mice from neonate to old age. By 2-dimensional electrophoresis (2-DE), matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and peptide mass fingerprint (PMF) analysis, 39 proteins were identified, among which 6 stayed unchanged since 3 months, 6 increased and 27 decreased in various manners during aging. They are mainly involved in processes usually with destructive changes during aging, such as metabolism, transport, signaling, stress response and apoptosis. The 27 proteins' decrease may be responsible for brain aging. In particular, decrease of proteasome alpha subunits 3/6, ubiquitin carboxyl-terminal esterase L3, valosin-containing protein and calreticulin may be responsible for the declination of protein quality control; glutamate dehydrogenase 1, isocitrate dehydrogenase 1 and ubiquinol cytochrome c reductase core protein 2 for the shortage of energy and reducing agent; ubiquitin-conjugating enzyme E2N and heterogeneous nuclear ribonucleoprotein A2/B1 for the increase of DNA damage and transcription detuning; calbindin 1 and amphiphysin for the disturbance of synaptic transport and ion signals. The six proteins' increase may be involved in anti-aging processes. In particular, transketolase, mitochondrial creatine kinase 1 and ribosomal protein L37 may help to enhance energy metabolism; triosephosphate isomerase 1 may help to resist oxidative stress. Moreover, most of these proteins were found for the first time to be involved in the natural senescence of brain, which would provide new clues about the mechanism of brain aging.
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PMID:Comparative proteomic analysis of brains of naturally aging mice. 1849 55

Benzo[a]pyrene (B[a]P) is an ubiquitous environmental carcinogen produced during incomplete combustion of organic substances. Anti-benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), is the most carcinogenic form of the ultimate metabolites of B[a]P. The goal of this study was to investigate the responses of human amniotic epithelial FL cells to BPDE at different time intervals after exposure and to find potential biomarkers involved in these responses. Cells were treated with 0.05 microM BPDE for 2 h and incubated for another 3, 12, and 24 h to obtain protein extracts which were resolved by 2-DE and visualized by silver staining. Sixty-four spots were up-regulated while 66 were down-regulated following BPDE exposure. These altered spots were excised from the gels and analyzed by MALDI-TOF-MS. The analysis led to the identification of 84 proteins affected by BPDE. These proteins were involved in regulation of transcription, cell cycle, apoptosis, transport, signal transduction, metabolism,and so forth. Among them, subunits of eukaryotic translation initiation factor 3 (EIF3) including EIF3S2, EIF3S3, EIF3S12, and EIF5A, component proteins of ubiquitin-proteasome system (ubiquitin carboxyl-terminal esterase L3, proteasome beta 4 subunit, and proteasome beta 3 subunit) and 14-3-3 proteins (14-3-3 zeta and epsilon) have not been previously associated with a response to BPDE exposure. All these results aid our understanding of the mechanism of BPDE induced cell defensive responses and hazardous effects as well as providing the possibility of the establishment of potential biomarkers.
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PMID:Translation initiation proteins, ubiquitin-proteasome system related proteins, and 14-3-3 proteins as response proteins in FL cells exposed to anti-benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide. 1875 15

Ubiquitin C-terminal hydrolases (UCHs) comprise a family of deubiquitinating enzymes that play a role in the removal of multi-ubiquitin chains from proteins that are posttranslationally modified by ubiquitination to be targeted for proteolysis by the 26S proteasome. The UCH-enzymes also generate free monomeric ubiquitin from precursor multi-ubiquitin chains and, in some instances, may rescue ubiquitinated proteins from degradation. This study examined the roles of two oocyte-expressed UCHs, UCHL1, and UCHL3 in murine and rhesus monkey oocyte maturation. The Uchl1 and Uchl3 mRNAs were highly expressed in GV and MII oocytes, and were associated with the oocyte cortex (UCHL1) and meiotic spindle (UCHL3). Microinjection of the UCH-family enzyme inhibitor, ubiquitin-aldehyde (UBAL) to GV oocytes prevented oocyte meiotic progression beyond metaphase I in a majority of treated oocytes and caused spindle and first polar body anomalies. Injection of antibodies against UCHL3 disrupted oocyte maturation and caused meiotic anomalies, including abnormally long meiotic spindles. A selective, cell permeant inhibitor of UCHL3, 4, 5, 6, 7-tetrachloroidan-1, 3-dione also caused meiotic defects and chromosome misalignment. Cortical granule localization in the oocyte cortex was disrupted by UBAL injected after oocyte maturation. We conclude that the activity of oocyte UCHs contributes to oocyte maturation by regulating the oocyte cortex and meiotic spindle.
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PMID:Essential role of ubiquitin C-terminal hydrolases UCHL1 and UCHL3 in mammalian oocyte maturation. 2175 Dec 13

Ubiquitin carboxy-terminal hydrolase L5 (UCHL5) is a proteasome-associated deubiquitinating enzyme, which, along with RPN11 and USP14, is known to carry out deubiquitination on proteasome. As a member of the ubiquitin carboxy-terminal hydrolase (UCH) family, UCHL5 is unusual because, unlike UCHL1 and UCHL3, it can process polyubiquitin chain. However, it does so only when it is bound to the proteasome; in its free form, it is capable of releasing only relatively small leaving groups from the C-terminus of ubiquitin. Such a behavior might suggest at least two catalytically distinct forms of the enzyme, an apo form incapable of chain processing activity, and a proteasome-induced activated form capable of cleaving polyubiquitin chain. Through the crystal structure analysis of two truncated constructs representing the catalytic domain (UCH domain) of this enzyme, we were able to visualize a state of this enzyme that we interpret as its inactive form, because the catalytic cysteine appears to be in an unproductive orientation. While this work was in progress, the structure of a different construct representing the UCH domain was reported; however, in that work the structure reported was that of an inactive mutant [catalytic Cys to Ala; Nishio K et al. (2009) Biochem Biophys Res Commun 390, 855-860], which precluded the observation that we are reporting here. Additionally, our structures reveal conformationally dynamic parts of the enzyme that may play a role in the structural transition to the more active form.
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PMID:Crystal structure of the catalytic domain of UCHL5, a proteasome-associated human deubiquitinating enzyme, reveals an unproductive form of the enzyme. 2199 38

Ubiquitination is a covalent post-translational modification of proteins by the chaperone protein ubiquitin. Upon docking to the 26S proteasome, ubiquitin is released from the substrate protein by deubiquitinating enzymes (DUBs). We hypothesised that specific inhibitors of two closely related oocyte DUBs, namely inhibitors of the ubiquitin C-terminal hydrolases (UCH) UCHL1 (L1 inhibitor) and UCHL3 (L3 inhibitor), would alter porcine oocyte maturation and influence sperm function and embryo development. Aberrant cortical granule (CG) migration and meiotic spindle defects were observed in oocytes matured with the L1 or L3 inhibitor. Embryo development was delayed or blocked in oocytes matured with the general DUB inhibitor PR-619. Aggresomes, the cellular stress-inducible aggregates of ubiquitinated proteins, formed in oocytes matured with L1 inhibitor or PR-619, a likely consequence of impaired protein turnover. Proteomic analysis identified the major vault protein (MVP) as the most prominent protein accumulated in oocytes matured with PR-619, suggesting that the inhibition of deubiquitination altered the turnover of MVP. The mitophagy/autophagy of sperm-contributed mitochondria inside the fertilised oocytes was hindered by DUB inhibitors. It is concluded that DUB inhibitors alter porcine oocyte maturation, fertilisation and preimplantation embryo development. By regulating the turnover of oocyte proteins and mono-ubiquitin regeneration, the DUBs may promote the acquisition of developmental competence during oocyte maturation.
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PMID:Protein deubiquitination during oocyte maturation influences sperm function during fertilisation, antipolyspermy defense and embryo development. 2484 20