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)

Dysfunction of the ubiquitin-proteasome system has recently been linked to stroke. Ischemia may cause increased protein misfolding and inhibit the proteasome, shifting the balance from free ubiquitin to conjugated ubiquitin. In this study, we examine the effect of hypothermia on the distribution of total and free ubiquitin, as well as the levels of conjugated ubiquitin after experimental stroke using a focal cerebral ischemia model. We show that hypothermia prevents redistribution of ubiquitin following ischemia, largely through preservation of intracellular cytoplasmic free ubiquitin. We also show that hypothermia blocks the increase in conjugated ubiquitin observed after stroke. Our data indicate that hypothermia's neuroprotection is mediated, in part, through preservation of ubiquitin-proteasome system function.
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PMID:Hypothermia blocks ischemic changes in ubiquitin distribution and levels following stroke. 1704 55

For over fifty years lithium has been a fundamental component of therapy for patients with bipolar disorders. Lithium has been considered recently for its potential to alleviate neuronal loss and other neurodegeneration processes. For instance, lithium reduces the severity of some behavioral complications of Alzheimer's disease (AD). And there are growing indications that lithium may be of benefit to the underlying pathology of AD, as well as an array of other common CNS disorders, including stroke, Parkinson's disease, and Huntington's disease. Despite these demonstrated and prospective therapeutic benefits, lithium's mechanism of action remains elusive, and opinions differ regarding the most relevant molecular targets. Lithium inhibits several enzymes; significant among these are inositol monophosphatase (IMPase), glycogen synthase kinase-3 (GSK-3), and the proteasome. Most recent publications discussing the medical application of lithium have converged on GSK-3, so this article reviews data and discussions regarding the roles and interactions of GSK-3 with other proteins and its proposed role in the pathogenesis of Alzheimer's disease.
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PMID:Glycogen synthase kinase-3 in neurodegeneration and neuroprotection: lessons from lithium. 1731 63

The 26S proteasome is a multicatalytic intracellular protease expressed in eukaryotic cells. It is responsible for selective degradation of intracellular proteins that are responsible for cell proliferation, growth, regulation of apoptosis and transcription of genes involved in execution of key cellular functions. Thus proteasome inhibition is a potential treatment option for cancer and diseases due to aberrant inflammation condition. Treatment with proteasome inhibitors results in stabilization and accumulation proteasome substrates, a phenomenon that may result in confounding signals in cells, cell cycle arrest and activation of apoptotic programs. The inhibition of the transcriptional factor nuclear factor kappaB (NF-kappaB) activation was found as one of crucial mechanisms in induction of apoptosis, overcoming resistance mechanisms and inhibition of immune response and inflammation mechanisms. Bortezomib (PS-341) and PS-519 are the first proteasome inhibitors that have entered clinical trials. In multiple myeloma, both the FDA (United States Food and Drug Administration) and EMEA (European Medicine Evaluation Agency) granted an approval for the use of bortezomib (Velcade) for the treatment of relapsed multiple myeloma. At present, several phase II and phase III trials in hematological malignancies and solid tumors are ongoing. PS-519 that focuses on inflammation, reperfusion injury and ischemia is currently under evaluation for the indication of acute stroke.
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PMID:Proteasome as an emerging therapeutic target in cancer. 1734 44

The adaptation of animals to oxygen availability is mediated by a transcription factor termed hypoxia-inducible factor (HIF). HIF is an alpha (alpha)/beta (beta) heterodimer that binds hypoxia response elements (HREs) of target genes, including some of medicinal importance, such as erythropoietin (EPO) and vascular endothelial growth factor (VEGF). While the concentration of the HIF-beta subunit, a constitutive nuclear protein, does not vary with oxygen availability, the abundance and activity of the HIF-alpha subunits are tightly regulated via oxygen-dependent modification of specific residues. Hydroxylation of prolyl residues (Pro402 and Pro564 in HIF-1alpha) promotes interaction with the von Hippel-Lindau E3 ubiquitin ligase and, consequently, proteolytic destruction by the ubiquitin-proteasome pathway. This prolyl hydroxylation is catalyzed by the prolyl-hydroxylase domain (PHD) containing enzymes for which three isozymes have been identified in humans (1-3). Additionally, asparaginyl hydroxylation (Asn803 in HIF-1alpha) by factor-inhibiting HIF (FIH) ablates interaction of the HIF-alpha subunit with the coactivator p300, providing an alternative mechanism for down-regulation of HIF-dependent genes. Under hypoxic conditions, when oxygen-mediated regulation of the alpha-subunits is curtailed or minimized, dimerization of the alpha- and beta-subunits occurs with subsequent target gene upregulation. Therapeutic activation of HIF signaling has been suggested as a potential treatment for numerous conditions, including ischemia, stroke, heart attack, inflammation, and wounding. One possible route to achieve this is via inhibition of the HIF hydroxylases. This chapter details methods for the purification and assaying of PHD2, the most abundant PHD and the most important in setting steady-state levels of HIF-alpha. Assays are described that measure the activity of PHD2 via direct and indirect means. Furthermore, conditions for the screening of small molecules against PHD2 are described.
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PMID:Hypoxia-inducible factor prolyl-hydroxylase: purification and assays of PHD2. 1799 47

Reactive oxygen species (ROS) are continuously generated during aerobic metabolism. Certain levels of ROS, which could be dependent on the type of cell, cell age, history of ROS exposure, etc., could facilitate specific cell functions. Indeed, ROS stimulate a number of stress responses and activate gene expression for a wide range of proteins. It is well known that increased levels of ROS are involved in the aging process and the pathogenesis of a number of neurodegenerative diseases. Because of the enhanced sensitivity of the central nervous system to ROS, it is especially important to maintain the normal redox state in different types of neuro cells. In the last decade it became clear that regular exercise beneficially affects brain function as well, and can play an important preventive and therapeutic role in stroke and in Alzheimer's and Parkinson's diseases. The effects of exercise appear to be very complex and could include neurogenesis via neurotrophic factors, increased capillarization, decreased oxidative damage, and increased proteolytic degradation by proteasome and neprilysin. Data from our and other laboratories indicate that exercise-induced modulation of ROS levels plays a role in the protein content and expression of brain-derived neurotrophic factor, tyrosine recepetor kinase B, and cAMP response element binding protein, resulting in better function and increased neurogenesis. The enhanced activities of proteasome and neprilysin result in decreased accumulation of carbonyls and amyloid beta-proteins, as well as improved memory. It appears that exercise-induced modulation of the redox state is an important means by which exercise benefits brain function, increases the resistance against oxidative stress, and facilitates recovery from oxidative stress.
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PMID:Effects of exercise on brain function: role of free radicals. 1805 20

A recent study from our laboratory indicated the cardioprotective ability of the tocotrienol-rich fraction (TRF) from red palm oil. The present study compared cardioprotective abilities of different isomers of tocotrienol against TRF as recently tocotrienol has been found to function as a potent neuroprotective agent against stroke. Rats were randomly assigned to one of the following groups: animals were given, by gavage, either 0.35%, 1%, or 3.5% TRF for two different periods of time (2 or 4 wk) or 0.03, 0.3, and 3 mg/kg body wt of one of the isomers of tocotrienol (alpha, gamma, or delta) for 4 wk; control animals were given, by gavage, vehicle only. After 2 or 4 wk, rats were killed, and their hearts were then subjected to 30 min of global ischemia followed by 2 h of reperfusion. Dose-response and time-response experiments revealed that the optimal concentration for TRF was 3.5% TRF and 0.3 mg/kg body wt of tocotrienol given for 4 wk. TRF as well as all the isomers of tocotrienol used in our study provided cardioprotection, as evidenced by their ability to improve postischemic ventricular function and reduce myocardial infarct size. The gamma-isoform of tocotrienol was the most cardioprotective of all the isomers followed by the alpha- and delta-isoforms. The molecular mechanisms of cardioprotection afforded by tocotrienol isoforms were probed by evaluating their respective abilities to stabilize the proteasome, allowing it to maintain a balance between prodeath and prosurvival signals. Our results demonstrated that tocotrienol isoforms reduced c-Src but increased the phosphorylation of Akt, thus generating a survival signal.
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PMID:Cardioprotection with palm oil tocotrienols: comparision of different isomers. 2283 19

The ubiquitin-proteasome system (UPS) displays an important cellular quality control function, by removing abnormal proteins from the cytosol, the nucleus and the endoplasmic reticulum. It controls the intracellular levels of short-lived and regulatory proteins, which are important for a variety of basic cellular processes. The pathway involves an enzymatic cascade through which multiple 76-amino acid ubiquitin monomers are covalently attached via a three-step process to the protein substrate, which is then degraded by the 26S proteasome complex. The proteasome is a cylindrical organelle that recognizes ubiquitinated proteins, degrades a large proportion of intracellular proteins, and recycles ubiquitin. Alterations in the proteasome proteolytic pathway have been thought to contribute to protein alterations associated with aging and, in fact, dysregulation of the UPS has been linked to several disease states including neurodegenerative diseases, malignancies, and inflammatory-related disorders. Strong preclinical data now exist supporting the use of reversible proteasome inhibitors to treat a variety of disease states including cancer, autoimmune and inflammatory diseases, myocardial infarction, and ischemic brain injury. Bortezomib (Velcade) has recently been licensed for the treatment of patients with multiple myeloma and is also undergoing further evaluation for the treatment of chronic lymphocytic leukemia (CLL) and a variety of solid tumors. MLN-519 is a small-molecular-weight lactacystin analogue and is being studied for the potential treatment of inflammatory disease and acute stroke. MLN-519 has demonstrated a neuroprotective effect in rat models of middle cerebral artery occlusion by reducing infarct volume, brain oedema and improving neurological outcome with a therapeutic window of up to 6-hrs. This review article focuses on the recent progress in the use of proteasome inhibitors in nervous system diseases with emphasis on the bench-to-bedside research effort which provided the foundation for clinical development of proteasome inhibitors in the treatment of neurological disorders.
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PMID:The ubiquitin-proteasome system and proteasome inhibitors in central nervous system diseases. 1822 Jul 25

Recent reports have demonstrated multiple benefits associated with the consumption of berry fruits, including a decreased vulnerability to oxidative stress, reduced ischemic brain damage, protection of neurons from stroke-induced damage and the reversal of age-related changes in brain and behaviour. Berry fruits contain high amounts of anthocyanins, which play a major role as free radical scavengers. The present study addresses proteasome inhibition as a further mechanism by which anthocyanins and their aglycons, the anthocyanidins, may exert health-promoting effects. HL-60 cells were incubated with 19 test substances and inhibition of the chymotrypsin-like enzyme activity was determined in a chemiluminescent assay. Anthocyanins and their aglycons achieved IC(50) values ranging from 7.8 microM for kaempferidinidin and pelargonidin, to 32.4 microM for delphinidin. Thus proteasome inhibitory properties of anthocyanins may contribute to their known anticarcinogenic, antioxidative, anti-inflammatory and neuroprotective activities, rationalizing dietary supplementations with anthocyanins in the prevention and treatment of chronic diseases, including neurodegenerative disorders.
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PMID:Inhibition of proteasome activity by anthocyanins and anthocyanidins. 1846 Mar 39

PR39, a naturally occurring and cell-permeable proline- and arginine-rich peptide, blocks the degradation of inhibitor of nuclear factor kappaB (IkappaBalpha), thereby attenuating inflammation. It is a noncompetitive and reversible inhibitor of 20S proteasome. To identify its basis of action, we used solution NMR spectroscopy and mutational analyses of the active fragment, PR11, which identified amino acids required for human 20S proteasome inhibiting activity. We then examined PR11-mediated changes in the expression of nuclear factor kappaB-dependent genes in situ. The results provide prerequisites for proteasome inhibition by proline- and arginine-rich peptides, providing a powerful new tool to investigate inflammatory processes. These findings offer new leads in developing drugs to treat heart diseases or stroke.
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PMID:Molecular basis for proline- and arginine-rich peptide inhibition of proteasome. 1882 92

Local axonal degeneration is a common pathological feature of peripheral neuropathies and neurodegenerative disorders of the central nervous system, including Alzheimer's disease, Parkinson's disease, and stroke; however, the underlying molecular mechanism is not known. Here, we analyzed the gracile axonal dystrophy (gad) mouse, which displays the dying-back-type of axonal degeneration in sensory neurons, to find the molecules involved in the mechanism of axonal degeneration. The gad mouse is analogous to a null mutant of ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1). UCH-L1 is a deubiquitinating enzyme expressed at high levels in neurons, as well as testis and ovary. In addition, we recently discovered a new function of UCH-L1-namely to bind to and stabilize mono-ubiquitin in neurons, and found that the level of mono-ubiquitin was decreased in neurons, especially in axons of the sciatic nerve, in gad mice. The low level of ubiquitin suggests that the target proteins of the ubiquitin proteasome system are not sufficiently ubiquitinated and thus degraded in the gad mouse; therefore, these proteins may be the key molecules involved in axonal degeneration. To identify molecules involved in axonal degeneration in gad mice, we compared protein expression in sciatic nerves between gad and wild-type mice at 2 and 12 weeks old, using two-dimensional difference gel electrophoresis. As a result, we found age-dependent accumulation of several proteins, including glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and 14-3-3, in gad mice compared with wild-type mice. Histochemical analyses demonstrated that GAPDH and 14-3-3 were localized throughout axons in both gad and wild-type mice, but GAPDH accumulated in the axons of gad mice. Recently, it has been suggested that a wide range of neurodegenerative diseases are characterized by the accumulation of intracellular and extracellular protein aggregates, and it has been reported that oxidative stress causes the aggregation of GAPDH. Furthermore, histochemical analysis demonstrated that sulfonated GAPDH, a sensor of oxidative stress that elicits cellular dysfunction, was expressed in the axons of gad mice, and 4-hydroxy-2-nonenal, a major marker of oxidative stress, was also only detected in gad mice. Our findings suggest that GAPDH may participate in a process of the dying-back-type of axonal degeneration in gad mice and may provide valuable insight into the mechanisms of axonal degeneration.
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PMID:Proteomic and histochemical analysis of proteins involved in the dying-back-type of axonal degeneration in the gracile axonal dystrophy (gad) mouse. 1915 71


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