Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tobacco smoke and polluted air are risk factors for lung cancer and contain many kinds of polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (B[a]P) and benz[a]anthracene (BA). BA, as well as B[a]P, is assessed as probably carcinogenic to humans (IARC group 2A). BA is metabolized to several dihydrodiols. Dihydrodiol dehydrogenase (DD), a member of the aldo-keto reductase superfamily, catalyzes NAD(P)+-linked oxidation of dihydrodiols of aromatic hydrocarbons to corresponding catechols. To clarify the role of DD on PAH carcinogenesis, we examined oxidative DNA damage induced by trans-dihydrodiols of BA and B[a]P treated with DD using 32P-5'-end-labeled DNA fragments obtained from the human p53 tumor suppressor gene. In addition, we investigated the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), an indicator of oxidative DNA damage, in calf thymus DNA by using HPLC with an electrochemical detector. DD-catalyzed BA-1,2-dihydrodiol caused Cu(II)-mediated DNA damage including 8-oxodG formation in the presence of NAD+. BA-1,2-dihydrodiol induced a Fpg sensitive and piperidine labile G lesion at the 5'-ACG-3' sequence complementary to codon 273 of the human p53 tumor suppressor gene, which is known as a hotspot. DNA damage was inhibited by catalase and bathocuproine, suggesting the involvement of H2O2 and Cu(I). The observation of NADH production by UV-visible spectroscopy suggested that DD catalyzed BA-1,2-dihydrodiol most efficiently to the corresponding catechol among the PAH-dihydrodiols tested. A time-of-flight mass spectroscopic study showed that the catechol form of BA-1,2-dihydrodiol formed after DD treatment. In conclusion, BA-1,2-dihydrodiol can induce DNA damage more efficiently than B[a]P-7,8-dihydrodiol and other BA-dihydrodiols in the presence of DD. The reaction mechanism on oxidative DNA damage may be explained by theoretical calculations with an enthalpy change of dihydrodiols and oxidation potential of their catechol forms. DD may play an important role in BA carcinogenesis via oxidative DNA damage.
 ...
PMID:Oxidative DNA damage induced by benz[a]anthracene dihydrodiols in the presence of dihydrodiol dehydrogenase. 1554 Sep 42

In lower organisms, increased expression of the NAD-dependent deacetylase Sir2 augments lifespan. The mechanism through which this life extension is mediated remains incompletely understood. Here we have examined the cellular effects of overexpression of SIRT1, the closest mammalian ortholog of Sir2. In PC12 cells, increased expression of the NAD-dependent deacetylase SIRT1 reduces cellular oxygen consumption by approximately 25%. We further demonstrate that SIRT1 expression can alter the transcriptional activity of the mitochondrial biogenesis coactivator PGC-1alpha. In addition, SIRT1 and PGC-1alpha directly interact and can be co-immunoprecipitated as a molecular complex. A single amino acid mutation in the putative ADP-ribosyltransferase domain of SIRT1 inhibits the interaction of SIRT1 with PGC-1alpha but does not effect the interaction of SIRT1 with either p53 or Foxo3a. We further show that PGC-1alpha is acetylated in vivo. This acetylation is augmented by treatment with the SIRT1 inhibitor nicotinamide or by expression of the transcriptional coactivator p300. Finally we demonstrate that SIRT1 catalyzes PGC-1alpha deacetylation both in vitro and in vivo. These results provide a direct link between the sirtuins, a family of proteins linked to lifespan determination and PGC-1alpha, a coactivator that regulates cellular metabolism.
 ...
PMID:SIRT1 functionally interacts with the metabolic regulator and transcriptional coactivator PGC-1{alpha}. 1571 68

The NAD+-dependent protein deacetylase family, Sir2 (or sirtuins), is important for many cellular processes including gene silencing, regulation of p53, fatty acid metabolism, cell cycle regulation, and life span extension. Resveratrol, a polyphenol found in wines and thought to harbor major health benefits, was reported to be an activator of Sir2 enzymes in vivo and in vitro. In addition, resveratrol was shown to increase life span in three model organisms through a Sir2-dependent pathway. Here, we investigated the molecular basis for Sir2 activation by resveratrol. Among the three enzymes tested (yeast Sir2, human SIRT1, and human SIRT2), only SIRT1 exhibited significant enzyme activation ( approximately 8-fold) using the commercially available Fluor de Lys kit (BioMol). To examine the requirements for resveratrol activation of SIRT1, we synthesized three p53 acetylpeptide substrates either lacking a fluorophore or containing a 7-amino-4-methylcoumarin (p53-AMC) or rhodamine 110 (p53-R110). Although SIRT1 activation was independent of the acetylpeptide sequence, resveratrol activation was completely dependent on the presence of a covalently attached fluorophore. Substrate competition studies indicated that the fluorophore decreased the binding affinity of the peptide, and, in the presence of resveratrol, fluorophore-containing substrates bound more tightly to SIRT1. Using available crystal structures, a model of SIRT1 bound to p53-AMC peptide was constructed. Without resveratrol, the coumarin of p53-AMC peptide is solvent-exposed and makes no significant contacts with SIRT1. We propose that binding of resveratrol to SIRT1 promotes a conformational change that better accommodates the attached coumarin group.
 ...
PMID:Mechanism of human SIRT1 activation by resveratrol. 1574 5

NAD(P)H:quinone oxidoreductase 1 (NQO1) is a cytosolic protein that catalyzes metabolic detoxification of quinones and protects cells against redox cycling and oxidative stress. NQO1-null mice deficient in NQO1 protein showed increased sensitivity to 7,12-dimethylbenz(a)anthracene- and benzo(a)pyrene-induced skin carcinogenesis. In the present studies, we show that benzo(a)pyrene metabolite benzo(a)pyrene-trans-7,8-dihydrodiol-9,10-epoxide and not benzo(a)pyrene quinones contributed to increased benzo(a) pyrene-induced skin tumors in NQO1-null mice. An analysis of untreated skin revealed an altered intracellular redox state due to accumulation of NADH and reduced levels of NAD/NADH in NQO1-null mice as compared with wild-type mice. Treatment with benzo(a)pyrene failed to significantly increase p53 and apoptosis in the skin of NQO1-null mice when compared with wild-type mice. These results led to the conclusion that altered intracellular redox state along with lack of induction of p53 and decreased apoptosis plays a significant role in increased sensitivity of NQO1-null mice to benzo(a)pyrene-induced skin cancer.
 ...
PMID:Lower induction of p53 and decreased apoptosis in NQO1-null mice lead to increased sensitivity to chemical-induced skin carcinogenesis. 1578 11

Poly(ADP-ribose) polymerase (PARP)-1 is a DNA nick sensor that transforms ADP-ribose from betaNAD+ in the form of polymer to over 40 nuclear proteins, particularly to histones, several transcription factors, and PARP itself, modulating their activities and functions. PARP-1 activated by DNA breaks facilitates transcription, replication, and DNA base excision repair. The last studies indicate that PARP-1 is the new nuclear target for fast signals evoked in cell membranes by depolarization and cholinergic and glutaminergic receptors stimulation. Excessive activation of PARP-1 by peroxynitrate-evoked DNA damage during oxidative stress can cause cell death by NAD+/ATP depletion after ischemia-reperfusion injury, inflammation, and diabetes mellitus. The PARP-1 through interaction with nuclear factor-kappaB, p53, and other transcription factors might significantly modulate cell survival and death and a type of death pathway. The pharmacological modulation of PARP-1 might offer a new effective approach for neuroprotection.
 ...
PMID:Poly(ADP-ribose) polymerase: the nuclear target in signal transduction and its role in brain ischemia-reperfusion injury. 1595 18

The development of ischemic tolerance in the brain, whereby a brief period of sublethal 'preconditioning' ischemia attenuates injury from subsequent severe ischemia, may involve the activation of multiple intracellular signaling events that promote neuronal survival. In this study, the potential role of inducible DNA base-excision repair (BER), an endogenous adaptive response that prevents the detrimental effect of oxidative DNA damage, has been studied in the rat model of ischemic tolerance produced by three episodes of ischemic preconditioning (IP). This paradigm of IP, when applied 2 and 5 days before 2-h middle cerebral artery occlusion (MCAO), significantly decreased infarct volume in the frontal-parietal cortex 72 h later. Correlated with this protective effect, IP markedly attenuated the nuclear accumulations of several oxidative DNA lesions, including 8-oxodG, AP sites, and DNA strand breaks, after 2-h MCAO. Consequently, harmful DNA damage-responsive events, including NAD depletion and p53 activation, were reduced during postischemic reperfusion in preconditioned brains. The mechanism underlying the decreased DNA damage in preconditioned brain was then investigated by measuring BER activities in nuclear extracts. Beta-polymerase-mediated BER activity was markedly increased after IP, and this activation occurred before (24 h) and during the course of ischemic tolerance (48 to 72 h). In similar patterns, the activities for AP site and 8-oxodG incisions were also upregulated after IP. The upregulation of BER activities after IP was likely because of increased expression of repair enzymes beta-polymerase, AP endonuclease, and OGG1. These results suggest that the activation of the BER pathway may contribute to IP-induced neuroprotection by enhancing the repair of endogenous oxidative DNA damage after ischemic injury.
 ...
PMID:Ischemic preconditioning in the rat brain enhances the repair of endogenous oxidative DNA damage by activating the base-excision repair pathway. 1600 Oct 17

Sir2 (silent information regulator 2) is an NAD-dependent deacetylase that is broadly conserved from bacteria to humans. It catalyzes a unique deacetylation reaction using NAD, and specific inhibitors and activators of its activity have been discovered. In yeast, Sir2 deacetylates histones and participates in transcription silencing and the suppression of recombination. Sir2 is also implicated in the regulation of aging, because its increased expression extends the lifespan of yeast and nematodes. Mammalian SIRT1 (Sir2alpha) is a member of the Sir2 family. Recently, SIRT1 was shown to interact with various transcription factors such as p53, forkhead transcription factor (FOXO) family proteins, and MyoD, and to participate in stress tolerance, differentiation, and development.
 ...
PMID:Transcriptional regulation of neuronal genes and its effect on neural functions: NAD-dependent histone deacetylase SIRT1 (Sir2alpha). 1600 43

Poly(ADP-ribosyl) ation is a reversible post-translational protein modification implicated in the regulation of a number of biological functions. Whereas an 18 member superfamily of poly(ADP-ribose) polymerase (PARP) enzymes synthesize poly(ADP-ribose) (PAR), a single protein, PAR glycohydrolase (PARG) is responsible for the catabolism of the polymer. PARP-1 accounts for more than 90% of the poly(ADP-ribosyl)ating capacity of the cells. PARP-1 activated by DNA breaks cleaves NAD(+) into nicotinamide and ADP-ribose and uses the latter to synthesize long branching PAR polymers covalently attached to acceptor proteins including histones, DNA repair enzymes, transcription factors and PARP-1. Whereas activation of PARP-1 by mild genotoxic stimuli may facilitate DNA repair and cell survival, irreparable DNA damage triggers apoptotic or necrotic cell death. In apoptosis, early PARP activation may assist the apoptotic cascade [e.g. by stabilizing p53, by mediating the translocation of apoptosis inducing factor (AIF) from the mitochondria to the nucleus or by inhibiting early activation of DNases]. In most severe oxidative stress situations, excessive DNA damage causes over activation of PARP-1, which incapacitates the apoptotic machinery and switches the mode of cell death from apoptosis to necrosis. Besides serving as a cytotoxic mediator, PARP-1 is also involved in transcriptional regulation, most notably in the NF kappaB and AP-1 driven expression of inflammatory mediators. Pharmacological inhibition or genetic ablation of PARP-1 provided remarkable protection from tissue injury in various oxidative stress-related disease models ranging from stroke, diabetes, diabetic endothelial dysfunction, myocardial ischemia-reperfusion, shock, Parkinson's disease, arthritis, colitis to dermatitis and uveitis. These beneficial effects are attributed to inhibition of the PARP-1 mediated suicidal pathway and to reduced expression of inflammatory cytokines and other mediators (e.g. inducible nitric oxide synthase).
 ...
PMID:Structure and function of poly(ADP-ribose) polymerase-1: role in oxidative stress-related pathologies. 1602 17

Sir2 is a NAD+-dependent protein deacetylase that extends lifespan in yeast and worms. This study examines seven human proteins homologous to Sir2 (SIRT1 through SIRT7) for cellular localization, expression profiles, protein deacetylation activity, and effects on human cell lifespan. We found that: 1) three nuclear SIRT proteins (SIRT1, SIRT6, and SIRT7) show different subnuclear localizations: SIRT6 and SIRT7 are associated with heterochromatic regions and nucleoli, respectively, where yeast Sir2 functions; 2) SIRT3, SIRT4, and SIRT5 are localized in mitochondria, an organelle that links aging and energy metabolism; 3) cellular p53 is a major in vivo substrate of SIRT1 deacetylase, but not the other six SIRT proteins; 4) SIRT1, but not the other two nuclear SIRT proteins, shows an in vitro deacetylase activity on histone H4 and p53 peptides; and 5) overexpression of any one of the seven SIRT proteins does not extend cellular replicative lifespan in normal human fibroblasts or prostate epithelial cells. This study supports the notion that multiple human SIRT proteins have evolutionarily conserved and nonconserved functions at different cellular locations and reveals that the lifespan of normal human cells, in contrast to that of lower eukaryotes, cannot be manipulated by increased expression of a single SIRT protein.
 ...
PMID:Evolutionarily conserved and nonconserved cellular localizations and functions of human SIRT proteins. 1607 81

Protein degradation is a key cellular process involved in almost every aspect of the living cell. The current prevailing concept is that proteins are stable unless marked by poly-ubiquitination for degradation by the proteasomes. Studies on the tumor suppressor p53 have indeed demonstrated that poly-ubiquitination of p53 by different E3 ubiquin ligases targets p53 for degradation by the 26S proteasomes. Recent findings suggest that p53 also undergoes ubiquitin-independent degradation by the 20S proteasomes and that this process is regulated by NAD(P)H quinone oxidoreductase 1 (NQO1) together with NADH. This "degradation by default" mechanism sheds new light on our understanding of p53 degradation and possibly on protein degradation in general and may establish a new principle in protein stability with wide physiological implications.
 ...
PMID:p53 proteasomal degradation: poly-ubiquitination is not the whole story. 1608 97


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