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

---

Query: EC:6.3.2.19 (ubiquitin-protein ligase)
799 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Serum and glucocorticoid-regulated kinase (SGK) plays a key role in the regulation of epithelial Na+ transport. SGK phosphorylates Nedd4-2, an E3 ubiquitin-protein ligase that targets the epithelial Na+ channel (ENaC) for degradation. Phosphorylation increases Na+ transport by reducing Nedd4-2 binding to ENaC, which increases ENaC expression at the cell surface. Thus, SGK expression must be tightly controlled to maintain Na+ homeostasis. This occurs in part by regulation of SGK transcription; a variety of signals including steroid hormones (aldosterone and glucocorticoids) increase SGK levels by inducing transcription of SGK. However, SGK has a short half-life, suggesting that SGK levels might also be controlled by regulation of SGK degradation. Here we found that SGK degradation is mediated in part by Nedd4-2. Consistent with this model, overexpression of Nedd4-2 decreased steady-state levels of SGK in a dose-dependent manner by increasing SGK ubiquitination and degradation in the 26S proteasome. Conversely, silencing of Nedd4-2 by RNA interference stabilized SGK. Nedd4-2 phosphorylation potentiates SGK degradation; degradation was reduced by Nedd4-2 and SGK mutations that disrupt phosphorylation or by inhibition of SGK kinase activity. Together with previous work, the data support a model in which SGK and Nedd4-2 regulate one another in a reciprocal manner. SGK phosphorylates Nedd4-2, which reduces Nedd4-2 binding and inhibition of ENaC. Conversely, phosphorylation increases Nedd4-2-mediated degradation of SGK. Thus, by phosphorylating Nedd4-2, SGK induces its own degradation. This feedback inhibition may fine-tune the regulation of epithelial Na+ absorption.
...
PMID:Nedd4-2 phosphorylation induces serum and glucocorticoid-regulated kinase (SGK) ubiquitination and degradation. 1557 72

We report a review on progress in the etiology and pathogenesis of Parkinson's disease (PD). We also report the long-term prognosis of PD patients seen in our clinic. Modern research on the pathogenesis started after the discovery of MPTP. We found inhibition of mitochondrial complex I by MPTP and MPP+. Mitochondrial respiratory failure induces oxidative damage to high molecular weight substances. Both mitochondrial failure and oxidative stress are important triggers of apoptosis. We found TUNEL positive nigral neurons in PD patients suggesting involvement of apoptosis in the pathogenesis. Interaction of genetic risk factors and environmental neurotoxins has been implicated in the etiology of PD. While we were investigating MnSOD gene polymorphism in PD patients, we found a young onset autosomal recessive PD family that was linked to the MnSOD locus. Subsequent linkage analysis on 13 families of young onset autosomal recessive families disclosed the linkage of this disease to the telomeric region of the long arm of chromosome 6 (6q25.2-27). Then we were lucky enough to find a patient who had a deletion of one of the microsatellite markers (D6S305) that we were using in the linkage analysis. We thought this marker might be located within the disease gene and this was the case. We screened the Keio BAC library with this marker, and eventually we cloned a novel gene encompassing 1.4 Mb; we named it parkin. The coding region consisted of 1,395 base pairs. The parkin protein had an unique sequence in that there was a 30% homology in the amino terminal region and two RING-finger motives on the carboxy terminal side. This unique structure suggested that the parkin protein was related to the ubiquitin-proteasome system. Parkin protein turned out to be an ubiquitin-protein ligase. Numbers of parkin-interacting proteins were reported in the literature and accumulation of parkin-substrates is likely to be the cause for the nigral neuronal death in this familial PD. Regarding the prognosis of PD, we analyzed the patients who visited our clinic from January 1, 1989 to December 31, 2002. The total of patients recruited was 1,772. The average age of onset was 57.2 years. Mean levodopa dose at the final examination was 479 mg/day. The most common initial symptom was tremor which was seen in 51% of the patients. Total percentage of patients who had tremor during the course of the disease was 75%. Long-term prognosis was evaluated on a subgroup of the patients who visited our clinic within 5 years from the onset and Hoehn and Yahr stage III or less when first seen. Analysis was done by the Kaplan-Meier survival curve. Percentages of patients who reached Hoehn and Yahr III 5, 10, and 15 years after the onset were 24%, 46%, and 65%, respectively. Percentages of patients who developed wearing off fluctuations were 5, 10, and 15 years after the start of levodopa were 18%, 46%, and 55%, respectively. Overall mortality on the total investigated patients was 7.9%. When compared to the age at death of Japanese population, mortality of men PD patients became very close to that of the general population in the year 2003. However, that in women PD patients showed significantly shorter survival compared to Japanese female population. Average ages of onset and the death were essentially similar between men and women PD patients. Survival curves to reach stage III and wearing off showed slightly but significantly faster time courses for women compared to those of men. This was an unexpected observation and its mechanism was discussed. It is our conclusion that overall prognosis of PD patients is improving and both patients and treating physicians should take an optimistic attitude to the disease.
...
PMID:[Progress in the basic and clinical aspects of Parkinson's disease]. 1565 Dec 81

p73, a member of the p53 family of transcription factors, is upregulated in response to DNA damage, inducing cell cycle arrest and apoptosis. Besides indications that this p73 response is post-transcriptional, little is known about the underlying molecular mechanisms of p73 protein degradation. Ubiquitination and proteasomal-dependent degradation of p53 are regulated by its transcriptional target MDM2. However, unlike p53, p73 binds to, but is not degraded by, MDM2. Here we describe the binding of p73 to Itch, a Hect ubiquitin-protein ligase. Itch selectively binds and ubiquitinates p73 but not p53; this results in the rapid proteasome-dependent degradation of p73. Upon DNA damage Itch itself is downregulated, allowing p73 protein levels to rise and thus interfere with p73 function. In conclusion, we have identified a key mechanism in the control of p73 protein levels both in normal as well as in stress conditions.
...
PMID:The ubiquitin-protein ligase Itch regulates p73 stability. 1567 6

Protein quality control degradation systems rid the cell of aberrant proteins, preventing detrimental effects on normal cellular function. Although such systems have been identified in most subcellular compartments, none have been found in the nucleus. Here, we report the discovery of such a system in Saccharomyces cerevisiae. It is defined by San1p, a ubiquitin-protein ligase that, in conjunction with the ubiquitin-conjugating enzymes Cdc34p and Ubc1p, targets four distinct mutant nuclear proteins for ubiquitination and destruction by the proteasome. San1p has exquisite specificity for aberrant proteins and does not target the wild-type versions of its mutant substrates. San1p is nuclear localized and requires nuclear localization for function. Loss of SAN1 results in a chronic stress response, underscoring its role of protein quality control in the cell. We propose that San1p-mediated degradation acts as the last line of proteolytic defense against the deleterious accumulation of aberrant proteins in the nucleus and that analogous systems exist in other eukaryotes.
...
PMID:Degradation-mediated protein quality control in the nucleus. 1579 74

Selective protein degradation by the 26S proteasome requires the covalent attachment of several ubiquitin molecules in the form of a multiubiquitin chain. Ubiquitylation usually involves three classes of enzymes: a ubiquitin-activating enzyme (E1), a ubiquitin-conjugating enzyme (E2) and a ubiquitin ligase (E3). However, in some cases, multiubiquitylation requires the additional activity of certain ubiquitin-chain elongation factors. Yeast UFD2 (ubiquitin fusion degradation), for example, binds to oligoubiquitylated substrates (proteins modified by only a few ubiquitin molecules) and catalyses multiubiquitin-chain assembly in collaboration with E1, E2 and E3. Enzymes possessing this specific activity have been proposed to be termed 'E4 enzymes'. Recent studies have provided accumulating evidence that has led some researchers in the field to conclude that E4, indeed, represents a distinct and novel class of enzymes.
...
PMID:Multiubiquitylation by E4 enzymes: 'one size' doesn't fit all. 1581 94

Recent characterization of several genes involved in plant defense responses suggested that ubiquitin-mediated protein degradation has a role in these responses. We isolated two cDNAs (NtUBA1 and NtUBA2) encoding ubiquitin-activating enzyme (E1) from Nicotiana tabacum cv. BY-2. The open reading frames of both encoded 1080 amino acids, corresponding to molecular masses of 120 kDa. The E1s and corresponding transcripts were upregulated by infection with tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV), and to a lesser extent by cucumber mosaic virus (CMV). Furthermore, they were also upregulated by wounding stress, and the plant hormones salicylic acid, jasmonic acid and the ethylene precursor, aminocyclopropane-1-carboxylic acid (ACC). Our findings support the idea that the ubiquitin-proteasome system plays a role in plant disease defenses.
...
PMID:The tobacco ubiquitin-activating enzymes NtE1A and NtE1B are induced by tobacco mosaic virus, wounding and stress hormones. 1587 7

Metabolic abnormalities develop in various chronic diseases and lead to progressive catabolism with decrements in the skeletal musculature that result in muscle atrophy. We investigated pathways of skeletal muscle proteolysis using an experimental model of chronic left-ventricular dysfunction. Skeletal muscle atrophy developed in wild-type mice 12 weeks following myocardial infarction accompanied by an increase in total protein ubiquitination and enhanced proteasome activity, activation of Foxo transcription factors, and robust induction of the ubiquitin-protein ligase atrogin-1/MAFbx. Further studies identified skeletal muscle myosin as a specific target of ubiquitin-mediated degradation in muscle atrophy. In contrast, transgenic overexpression of a local isoform of insulin-like growth factor-1 prevented muscle atrophy and increased proteasome activity, inhibited skeletal muscle activation primarily of Foxo4, and blocked the expression of atrogin-1/MAFbx. These results suggest that skeletal muscle atrophy occurs through increased activity of the ubiquitin-proteasome pathway. The inhibition of muscle atrophy by local insulin-like growth factor-1 provides a promising therapeutic avenue for the prevention of skeletal muscle wasting in chronic heart failure and potentially other chronic diseases associated with skeletal muscle atrophy.
...
PMID:Transgenic overexpression of locally acting insulin-like growth factor-1 inhibits ubiquitin-mediated muscle atrophy in chronic left-ventricular dysfunction. 1614 Nov 15

Selective protein degradation by the 26 S proteasome usually requires a polyubiquitin chain attached to the protein substrate by three classes of enzymes: a ubiquitin-activating enzyme (E1), a ubiquitin-conjugating enzyme (E2), and a ubiquitin ligase (E3). This reaction can produce different polyubiquitin chains that, depending on size and linkage type, can provide distinct intracellular signals. Interestingly, polyubiquitination is sometimes regulated by additional conjugation factors, called E4s (polyubiquitin chain conjugation factors). Yeast UFD2 (ubiquitin fusion degradation protein-2), the first E4 to be described, binds to the ubiquitin moieties of preformed conjugates and catalyses ubiquitin-chain elongation together with E1, E2, and E3. Recent studies have illustrated that the E4 enzyme UFD2 co-operates with an orchestra of ubiquitin-binding factors in an escort pathway to transfer and deliver polyubiquitinated substrates to the 26 S proteasome. Here we propose a model in which E4-dependent polyubiquitination pathways are modulated by different ubiquitin-binding proteins, using ataxin-3 as an example.
...
PMID:Orchestra for assembly and fate of polyubiquitin chains. 1625 Aug 94

The selectivity of the ubiquitin-26 S proteasome system (UPS) for a particular substrate protein relies on the interaction between a ubiquitin-conjugating enzyme (E2, of which a cell contains relatively few) and a ubiquitin-protein ligase (E3, of which there are possibly hundreds). Post-translational modifications of the protein substrate, such as phosphorylation or hydroxylation, are often required prior to its selection. In this way, the precise spatio-temporal targeting and degradation of a given substrate can be achieved. The E3s are a large, diverse group of proteins, characterized by one of several defining motifs. These include a HECT (homologous to E6-associated protein C-terminus), RING (really interesting new gene) or U-box (a modified RING motif without the full complement of Zn2+-binding ligands) domain. Whereas HECT E3s have a direct role in catalysis during ubiquitination, RING and U-box E3s facilitate protein ubiquitination. These latter two E3 types act as adaptor-like molecules. They bring an E2 and a substrate into sufficiently close proximity to promote the substrate's ubiquitination. Although many RING-type E3s, such as MDM2 (murine double minute clone 2 oncoprotein) and c-Cbl, can apparently act alone, others are found as components of much larger multi-protein complexes, such as the anaphase-promoting complex. Taken together, these multifaceted properties and interactions enable E3s to provide a powerful, and specific, mechanism for protein clearance within all cells of eukaryotic organisms. The importance of E3s is highlighted by the number of normal cellular processes they regulate, and the number of diseases associated with their loss of function or inappropriate targeting.
...
PMID:E3 ubiquitin ligases. 1625 Aug 95

Previous work from this laboratory had shown that ligases may catalyze the synthesis of (di)nucleoside polyphosphates. Here, we show that one of the enzymes of the proteasome system (E1 or the ubiquitin (Ub) activating enzyme, EC 6.3.2.19) catalyzes very effectively (k(cat) = 0.29+/-0.05 s(-1)) the transfer of AMP from the E-AMP-ubiquitin complex to tripolyphosphate or tetrapolyphosphate with formation of adenosine tetra- or pentaphosphate (p4A or p5A), respectively. Whereas the concomitant formation of AMP is stimulated by the presence of dithiothreitol in a concentration dependent manner, the synthesis of p4A is only slightly inhibited by this compound. Previous treatment of the enzyme (E1) with iodoacetamide inhibited only partially the synthesis of p4A. p4A can substitute for ATP as substrate of the reaction to generate the ubiquityl adenylate complex. A small amount of diadenosine pentaphosphate (Ap5A) was also synthesized in the presence of p4A.
...
PMID:Synthesis of (di)nucleoside polyphosphates by the ubiquitin activating enzyme E1. 1625 13


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---