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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We previously reported increased aortic reactive oxygen species (ROS) production in mineralocorticoid (deoxycorticosterone acetate [DOCA]-salt) hypertensive rats. In the present study, we tested the hypothesis that NADH/NADPH oxidase is responsible for increased ROS production, namely superoxide (O(2-)), in aorta from the DOCA-salt rat. Treatment of aortic rings from DOCA-salt rats with the NO synthase inhibitor N-nitro-L-arginine and the xanthine oxidase inhibitor allopurinol did not significantly change O(2-) production. Furthermore, de-endothelialization of aorta from DOCA-salt rats did not affect O(2-) production compared with that of sham-operated rats. Thus, xanthine oxidase and uncoupled endothelial NO synthase were not responsible for increased O(2-) production in the DOCA-salt rats. In contrast, treatment with the NADPH oxidase inhibitor apocynin significantly decreased O(2-) production in aortic rings from DOCA-salt rats compared with sham-operated rats. Moreover, long-term administration of apocynin (in drinking water, 1.5 mmol/L, 28 days) to DOCA-salt rats significantly decreased systolic blood pressure compared with that of rats treated with DOCA-salt alone. Furthermore, O(2-) production in aortic rings from DOCA-salt rats treated with apocynin for 28 days was reduced compared with that of untreated DOCA-salt rats. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis demonstrated that DOCA-salt rats have significantly greater mRNA levels of the NADPH oxidase subunit p22phox than do sham-operated rats. These findings suggest that NADPH oxidase is increased and is responsible for increased O(2-) production and possibly contributes to increased blood pressure in the DOCA-salt hypertensive rat.
...
PMID:NADH/NADPH oxidase and enhanced superoxide production in the mineralocorticoid hypertensive rat. 1171 6

A naturally occurring atrazine-resistant cyanobacterial isolate, strain SG2, was isolated from an atrazine-containing wastewater treatment system at the Syngenta atrazine production facility in St. Gabriel, La. Strain SG2 was resistant to 1,000 microg of atrazine per ml but showed relatively low resistance to diuron [3-(3,4-dichlorophenyl)-1,1-dimethyl urea]. Analyses of 16S ribosomal DNA indicated that strain SG2 falls into the Synechocystis/Pleurocapsa/Microcystis group. Photosynthetically driven oxygen evolution in strain SG2 was only slightly inhibited (about 10%) by 2,000 microg of atrazine per ml, whereas in the control strain Synechocystis 6803, oxygen evolution was inhibited 90% by 1,000 microg of atrazine per ml. No atrazine accretion, mineralization, or metabolites were detected when strain SG2 was grown with [(14)C]atrazine. Strain SG2 contained three copies of the psbA gene, which encodes the D(1) protein of the photosystem II reaction center. Nucleotide sequence analyses indicated that the psbA2 and psbA3 genes encoded predicted proteins with the same amino acid sequence. However, the psbA1 gene product contained five extra amino acids, which were not found in PsbA proteins from five other cyanobacteria. Moreover, the PsbA1 protein from strain SG2 had an additional 13 amino acid changes compared to the PsbA2/PsbA3 proteins and contained 10 amino acid alterations compared to conserved residues found in other cyanobacteria. Reverse transcriptase PCR analysis indicated that the psbA1 gene and the psbA2/psbA3 gene(s) were expressed in photosynthetically grown cells in the presence of atrazine. These results suggest that strong selection pressure conferred by the continual input of atrazine has contributed to the evolution of a herbicide-resistant, yet photosynthetically efficient, psbA gene in a cyanobacterium.
...
PMID:Novel psbA1 gene from a naturally occurring atrazine-resistant cyanobacterial isolate. 1187 88

The transcriptome of Saccharomyces cerevisiae was screened using the high-density membrane hybridization method, under aerobic and hypoxic conditions, in wild-type and mutant backgrounds obtained by the disruption of the genes encoding the regulatory proteins Hap1, Rox1 and the Srb10 and Rox3 subunits of RNA polymerase II holoenzyme. None of the mutations studied was able to fully overcome the wild-type hypoxic response. Deletion of the hap1 gene changed the expression profiles of individual open reading frames (ORFs) under both aerobic and hypoxic conditions. Major changes associated with rox3 deletion were related to the hypoxic activation. Rox3 also caused a repressor effect (oxygen-independent) on a subset of genes related to subtelomeric proteins. With regard to the effect brought about by the deletion of rox1 and srb10, correspondence cluster analysis revealed that the transcriptome profile in aerobic conditions is very similar in the wild-type and both deletion strains. In contrast, however, differences were found during hypoxia between the subgroup formed by wild-type and the Deltarox1 deletant compared with the Deltasrb10 deletant. An analysis of selected ORFs responding to hypoxia, in association with a dependence on the regulatory factors studied, made it possible to identify the clusters that are related to different regulatory circuits.
...
PMID:The yeast transcriptome in aerobic and hypoxic conditions: effects of hap1, rox1, rox3 and srb10 deletions. 1192 14

It is becoming increasingly evident that the degradation of nuclear proteins requires nuclear-cytoplasmic trafficking of both the substrate proteins, as well as the E3 ubiquitin-ligases. Here, we show that nuclear-cytoplasmic trafficking of the von Hippel-Lindau tumor suppressor protein (VHL) is required for oxygen-dependent ubiquitination and degradation of the alpha subunits of hypoxia-inducible factor (HIF-alpha). VHL engages in a constitutive transcription-sensitive nuclear-cytoplasmic shuttle unaffected by oxygen tension or levels of nuclear substrate HIF-alpha. Ubiquitinated forms of HIF-alpha, as well as VHL/ubiquitinated HIF-alpha complexes, are found solely in the nuclear compartment of normoxic or reoxygenated VHL-competent cells. HIF-alpha localizes exclusively in the nucleus of hypoxic cells but is exported to the cytoplasm upon reoxygenation. Oxygen-dependent nuclear ubiquitination and nuclear export of HIF-alpha can be prevented by treatment with an HIF-specific prolyl hydroxylase inhibitor. Treatment with inhibitors of RNA polymerase II activity, which interfere with the ability of VHL to engage in nuclear export, also prevents cytoplasmic accumulation of HIF-alpha in reoxygenated cells. This caused a marked increase in the HIF-alpha half-life without affecting its nuclear ubiquitination. We present a model by which VHL-mediated ubiquitination of HIF-alpha and its subsequent degradation are dependent upon dynamic nuclear-cytoplasmic trafficking of both the E3 ubiquitin-ligase and the nuclear substrate protein.
...
PMID:Oxygen-dependent ubiquitination and degradation of hypoxia-inducible factor requires nuclear-cytoplasmic trafficking of the von Hippel-Lindau tumor suppressor protein. 1210 Dec 28

Increased formation of reactive oxygen species is a cause of paraquat (PQ)-induced injury and also provides a link between the signaling pathways and transcriptional events that regulate the expression of a large number of genes. However, the molecular mechanisms involved in PQ-induced injury remain unclear. To investigate the changes in gene expression at the onset of PQ injury, we used the differential display-polymerase chain reaction (PCR) method. Rats were treated intraperitoneally with 20 mg/kg PQ, and after 3 h the lungs were immediately excised. Samples of mRNA from normal and treated rats were used to prepare radiolabeled cDNAs, which were electrophoresed. Then the transcription levels were compared. We isolated 26 fragments of cDNA that were potentially affected by PQ, and determined their nucleotide sequences. Six clones of interest were selected and analyzed further. The reverse transcript-PCR based on their sequence information confirmed the differential expression for five clones: four clones were up-regulated and one was down-regulated. We were particularly interested in two genes that had homology with the known gene: TATA box-binding protein-associated factor, RNA polymerase II, B, 150 kDa (TAFIIB), and a candidate gene for lipodystrophy, Lpin2. Both genes were significantly up-regulated within 3 h of PQ intake and the stimulation continued during our 24-h observation period. In addition, up-regulation of Lpin2 was observed in the lungs, but not in the liver and kidneys. In situ hybridization using lung sections showed that the expression of both genes was strongly visualized in Clara cells and in alveolar macrophages. These findings suggest a stimulation of transcription levels and changes in lipid metabolism in Clara cells and in macrophages in the lungs, which result in their playing a crucial role at the onset of PQ-driven pulmonary injury.
...
PMID:Paraquat-induced gene expression in rat lung tissues using a differential display reverse transcription-polymerase chain reaction. 1224 11

The FNR protein of Escherichia coli controls the transcription of target genes in response to anoxia via the assembly-disassembly of oxygen-labile iron-sulfur clusters. Previous work identified patches of surface-exposed amino acids (designated activating regions 1 and 3 [AR1 and AR3, respectively]) of FNR which allow it to communicate with RNA polymerase (RNAP) and thereby activate transcription. Previously it was thought that FNR lacks a functional activating region 2 (AR2), although selecting for mutations that compensate for defective AR1 or a miscoordinated iron-sulfur cluster can reactivate AR2. Here we show that the substitution of two surface-exposed lysine residues (Lys49 and Lys50) of FNR impaired transcription from class II (FNR box centered at -41.5) but not class I (FNR box centered at -71.5) FNR-dependent promoters. The degree of impairment was greater when a negatively charged residue (Glu) replaced either Lys49 or Lys50 than when uncharged amino acid Ala was substituted. Oriented heterodimers were used to show that only the downstream subunit of the FNR dimer was affected by the Lys-->Ala substitutions at a class II promoter. Site-directed mutagenesis of a negatively charged patch ((162)EEDE(165)) within the N-terminal domain of the RNAP alpha subunit that interacts with the positively charged AR2 of the cyclic AMP receptor protein suggested that Lys49 and Lys50 of FNR interact with this region of the alpha subunit of RNAP. Thus, it was suggested that Lys49 and Lys50 form part of a functional AR2 in FNR.
...
PMID:Transcription activation by FNR: evidence for a functional activating region 2. 1237 18

Salmonella enterica serovar Typhimurium causes human gastroenteritis and a systemic typhoid-like infection in mice. Infection is initiated by entry of the bacteria into intestinal epithelial cells and is mediated by a type III secretion system that is encoded by genes in Salmonella pathogenicity island 1. The expression of invasion genes is tightly regulated by environmental conditions such as oxygen and osmolarity, as well as by many bacterial factors. The hilA gene encodes an OmpR/ToxR family transcriptional regulator that activates the expression of invasion genes in response to both environmental and genetic regulatory factors. HilD is an AraC/XylS regulator that has been postulated to act as a derepressor of hilA expression that promotes transcription by interfering with repressor binding at the hilA promoter. Our research group has identified four genes (hilE, hha, pag, and ams) that negatively affect hilA transcription. Since the postulated function of HilD at the hilA promoter is to counteract the effects of repressors, we examined this model by measuring hilA::Tn5lacZY expression in strains containing negative regulator mutations in the presence or absence of functional HilD. Single negative regulator mutations caused significant derepression of hilA expression, and two or more negative regulator mutations led to very high level expression of hilA. However, in all strains tested, the absence of hilD resulted in low-level expression of hilA, suggesting that HilD is required for activation of hilA expression, whether or not negative regulators are present. We also observed that deletion of the HilD binding sites in the chromosomal hilA promoter severely decreased hilA expression. In addition, we found that a single point mutation at leucine 289 in the C-terminal domain of the alpha subunit of RNA polymerase leads to very low levels of hilA::Tn5lacZY expression, suggesting that HilD activates transcription of hilA by contacting and recruiting RNA polymerase to the hilA promoter.
...
PMID:Transcription of the Salmonella invasion gene activator, hilA, requires HilD activation in the absence of negative regulators. 1251 99

The rise in alveolar oxygen tension (PO(2)) that occurs as the newborn infant takes its first breaths induces removal of liquid from the lung lumen due to ion transport across the alveolar epithelium and the activity of alveolar Na(+) channel (ENaC). In the present study, we have aimed to identify an ion conductance in alveolar epithelial A549 cells that responds to acute changes in PO(2). Variation in PO(2) did not affect single-channel ENaC activity. However, in these cells we have detected single-channel conductance having properties similar to those of large conductance Ca(2+)-activated K(+) (BK(Ca)) channels. Reverse transcriptase-polymerase chain reaction and Western blotting demonstrated presence of alpha-BKCa channel subunit and iberiotoxin, a blocker of BK(Ca) channels, inhibited whole cell K(+) current. Chronic changes in PO(2) did not affect expression, recruitment, or function of BK(Ca) channels in A549 cells. In contrast, acute changes of PO(2) regulated the BK(Ca) channel activity by controlling the channel mean open time. This effect of PO(2) was insensitive to inhibitor of flavoproteins, diphenylene iodinium. In addition, decrease in PO(2) and iberiotoxin induced membrane depolarization and Ca(2+) oscillations in A549 cells. We conclude that BK(Ca) channels serve as oxygen sensors in human alveolar A549 epithelial cells.
...
PMID:Large conductance Ca2+-activated K+ channels sense acute changes in oxygen tension in alveolar epithelial cells. 1259 63

Nucleoside diphosphate kinases (NDPKs) are conserved throughout evolution and have been shown to be involved in various biological phenomena. By functional screening in yeast, we identified a new member of the NDPK family, nm23-M5, which encodes a 211-amino acid protein with 86% identity to the human homolog Nm23-H5. Northern blot analysis revealed that nm23-M5 encodes two transcripts of 0.8 and 0.7kb, which are highly and specifically expressed in adult testis. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed that nm23-M5 transcripts first appear in pachytene spermatocytes and increase in abundance in subsequent stages. However, a low level of nm23-M5 mRNA was detected by RT-PCR in other tissues, such as ovary, brain, heart, and kidney. In situ hybridization studies showed that testicular nm23-M5 transcripts are localized in stage 12 to stage 16 spermatids in the neighboring lumen of seminiferous tubules. This distribution contrasts with that of Nm23-H5 transcripts, which are specifically found in spermatogonia and early spermatocytes. The heterologous expression of nm23-M5 in yeast cells confers protection from cell death induced by Bax, which is due to the generation of reactive oxygen species. Furthermore, overexpression of nm23-M5 in fibroblasts altered the cellular levels of several antioxidant enzymes, particularly glutathione peroxidase 5. Thus, we believe that the murine nm23-M5 gene plays an important role in late spermiogenesis by elevating the ability of late-stage spermatids to eliminate reactive oxygen species.
...
PMID:Cloning, sequencing, and characterization of the murine nm23-M5 gene during mouse spermatogenesis and spermiogenesis. 1278 88

DNA damage-induced ubiquitination of the largest subunit of RNA polymerase II, Rpb1, has been implicated in transcription-coupled repair for years. The studies so far, however, have been limited to the use of bulky helix-distorting DNA damages caused by UV light and cisplatin, which are corrected by the nucleotide excision repair pathway. Non-bulky, non-helix-distorting damages are caused at high frequency by reactive oxygen species in cells and corrected by the base excision repair pathway. Contrary to a classic view, we recently found that the second type of DNA lesions also causes RNA polymerase II stalling in vitro. In this paper, we show that hydrogen peroxide (H(2)O(2)) causes significant ubiquitination and proteasomal degradation of Rpb1 by mechanisms that are distinct from those employed after UV irradiation. UV irradiation and H(2)O(2) treatment cause characteristic changes in protein kinases phosphorylating the carboxyl-terminal domain at Ser-2 and -5. The H(2)O(2)-induced ubiquitination is likely dependent on unusual Ser-5 phosphorylation by ERK1/2. Moreover, the H(2)O(2)-induced ubiquitination occurs on transcriptionally engaged polymerases without the help of Cockayne syndrome A and B proteins and von Hippel-Lindau tumor suppressor proteins, which are all required for the UV-induced ubiquitination. These results suggest that stalled polymerases are recognized and ubiquitinated differentially depending on the types of DNA lesions. Our findings may have general implications in the basic mechanism of transcription-coupled nucleotide excision repair and base excision repair.
...
PMID:A novel hydrogen peroxide-induced phosphorylation and ubiquitination pathway leading to RNA polymerase II proteolysis. 1466 62


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

---