Note: This page contains sample records for the topic 17beta-estradiol e2 plasmatico from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Effects of 17beta-estradiol on mussel digestive gland.  

PubMed

In bivalve molluscs the digestive gland (hepatopancreas) plays a central role in metabolism. In this work, the effects of 17beta-estradiol (E(2)) on digestive gland were evaluated in Mytilus galloprovincialis. Mussels were injected into the adductor muscle sinus with different amounts of the hormone (5, 25 and 100pmol) and tissues were sampled 24h post-injection. Functional parameters (lysosomal membrane stability-LMS, lysosomal accumulation of neutral lipids-NL and of lipofuscin-LF), as well as the activity of the key glycolytic enzymes PFK (phosphofructokinase) and PK (pyruvate kinase), and of the antioxidant enzyme catalase were evaluated. Selected genes, whose expression can be modulated by estrogens in mammalian systems and whose sequences have been identified in Mytilus, were investigated as possible targets for the action of E(2). E(2) induced a concentration-dependent decrease in LMS; such an effect was accompanied by an increase in NL accumulation, whereas the level of lipofuscin showed a slight, although not significant decrease. E(2) exposure also led to a significant increase in the activity of PFK and catalase but not of PK. Moreover, E(2) induced significant changes in the pattern of gene expression at the lower concentrations tested (5 and 25pmol) as evaluated by quantitative RT-PCR. In particular, increased transcription of catalase, as well as of the metallothionein 20 (MT20) isoform were observed; on the other hand, a decreased transcription of the p53 gene was detected. The results demonstrate that in Mytilus the digestive gland represents a target for the action of E(2), and that the hormone can modulate the lysosomal function, as well as lipid and glucose metabolism. Moreover, these data suggest that E(2) may also alter oxidative stress conditions in this tissue, as indicated by the increased transcription of genes (metallothionein and catalase) that play a role in antioxidant defences. Overall, the results indicate that E(2) can modulate both functional parameters and gene expression in mussel hepatopancreas and underline the importance of investigating also non-reproductive effects of estrogenic compounds in bivalve molluscs. PMID:17376445

Canesi, Laura; Borghi, Cristina; Fabbri, Rita; Ciacci, Caterina; Lorusso, Lucia Cecilia; Gallo, Gabriella; Vergani, Laura

2007-02-12

2

Ovulation inhibition with 17 beta-estradiol cyclo-octyl acetate and desogestrel.  

PubMed

Ovulation inhibition and bleeding control with a combination of 0.5 mg 17 beta-estradiol cyclo-octyl acetate (E2COA) and 0.15 mg desogestrel was investigated in 10 regularly menstruating women for 21 days. In half the group the treatment was extended for 7 days (days 22-28) with 0.03 mg desogestrel in order to evaluate any posttreatment influence on the gonadotropin levels. E2COA, beeing a long-chain fatty ester dissolved in oil, was expected to be resorbed from the intestinal wall via the lymphatic system. By incorporating it in the chylomicrons, E2COA would thereby avoid the unfavourable first liver pass. The serum levels of progesterone were suppressed during treatment. No increase in 17 beta-estradiol (E2) concentration was found; levels remained low and even during medication. No peak values of gonadotropins were seen. Thus follicular hormonal activity and ovulation was inhibited by this combination. Bleeding control was, however unacceptable in all volunteers. The addition of desogestrel during the fourth investigation week apparently did not induce any hormonal differences. The estrogenic activity is shown by the low, even S-E2 levels, but the dosage of E2COA seems to be too low in relation to progestogen dosage. Further studies will have to be performed in order to find the ideal combination. PMID:2962418

Schubert, W; Cullberg, G

1987-01-01

3

Fat-soluble 17 beta-estradiol: a way of reducing dosage in steroid hormonal substitution?  

PubMed

Eight ovariectomized women were given 0.5 mg 17 beta-estradiol cyclo-octyl acetate (E2COA) dissolved in arachis oil + 0.15 mg desogestrel, and 2 mg micronized 17 beta-estradiol (mE2) + 0.15 mg desogestrel orally in a crossover fashion for 20 days each. The preparations were taken on 10 days together with a meal, on 10 days 3 hours after a meal. Blood samplings were performed 3 h after capsule ingestion for analysis of serum estradiol (S-E2), estrone (S-E1) and sex hormone binding globulin (SHBG). Before treatment, all women had climacteric complaints. During treatment these symptoms were alleviated and no discomfort was reported. No differences in serum levels of estrogens were found in either of the preparations when capsules were taken with or without food. However, serum levels of E2 were found to be 100% higher per mg substance given after E2COA vis-à-vis mE2. This indicates either a delayed breakdown and/or a better resorption. The E1/E2 ratio after E2COA was only half that after mE2 intake. This hints at another route of resorption. SHBG concentrations were somewhat elevated following mE2 administration, whereas a slight decrease was found after E2COA. The resulting post-treatment difference was significant, suggesting a less estrogenic liver effect by E2COA. No accumulation of E2 or E1 was seen after either of the preparations. Our findings support the hypothesis that E2COA, being fat soluble, is resorbed via the lymphatic system. By avoiding the first liver pass the dosage of estrogen can be halved. PMID:2972162

Schubert, W; Cullberg, G

1988-01-01

4

17beta-estradiol attenuates vascular contraction through inhibition of RhoA/Rho kinase pathway.  

PubMed

We hypothesized that 17beta-estradiol attenuates vascular contraction through inhibition of RhoA/Rho kinase pathway. Rat aortic rings were contracted with cumulative addition of U46619, NaF, KCl or PDBu 30 min after pretreatment with 17beta-estradiol (10, 30, and 100 microM) or vehicle. We measured the amount of GTP RhoA and the level of phosphorylation of the myosin light chain (MLC(20)), myosin phosphatase targeting subunit 1 (MYPT1) and PKC-potentiated inhibitory protein for heterotrimeric MLCP of 17 kDa (CPI17). Pretreatment with 17beta-estradiol dose-dependently inhibited the concentration-response curves in response to U46619, NaF or KCl, but not to PDBu. 17beta-Estradiol decreased not only the level of phosphorylation of MYPT1(Thr855) and CPI17(Thr38) as well as MLC(20), but also the activity of RhoA induced by U46619 or NaF. However, 17beta-estradiol did not affect the level of phosphorylation of CPI17 induced by PDBu. 17beta-Estradiol attenuates vascular contraction through inhibition of RhoA/Rho kinase pathway. PMID:19296091

Yang, Enyue; Jeon, Su Bun; Baek, Inji; Chen, Zheng-Ai; Jin, Zheng; Kim, In Kyeom

2009-03-19

5

Effects of 17beta-estradiol on cytokine-induced endothelial cell adhesion molecule expression.  

PubMed Central

One of the earliest events in atherosclerosis is interaction of circulating mononuclear leukocytes and the endothelium. Endothelial cell (EC) activation by cytokines results in expression of adhesion molecules and production of chemotactic factors, augmenting leukocyte adhesion and recruitment, respectively. The incidence of atherosclerosis in premenopausal women is significantly less than that observed in age-matched males with similar risk profiles. Because estrogen has gene regulatory effects, we investigated whether 17beta-estradiol (E2) can inhibit cytokine-mediated EC adhesion molecule transcriptional activation. Cultured human umbilical vein EC (estrogen receptor-positive) were propagated in gonadal hormone-free medium and were E2-pretreated for 48 h before IL-1 activation. Detected by FACS analysis, E2 strongly (60-80%) inhibited IL-1-mediated membrane E-selectin and vascular cell adhesion molecule-1 induction, and intercellular adhesion molecule-1 hyperinduction. 17alpha-estradiol (an inactive E2 stereoisomer) had no effect. This inhibition correlated with similar reductions in steady state-induced E-selectin mRNA levels, and was abrogated by the E2 antagonist ICI 164,384, demonstrating a specific, estrogen receptor-mediated effect. Nuclear run-offs confirmed suppression at the transcriptional level. The implications of these results for the cardiovascular protective role of estrogen are discussed.

Caulin-Glaser, T; Watson, C A; Pardi, R; Bender, J R

1996-01-01

6

Modulation of ovine SBD-1 expression by 17beta-estradiol in ovine oviduct epithelial cells  

PubMed Central

Background Mucosal epithelia, including those of the oviduct, secrete antimicrobial innate immune molecules (AIIMS). These have bactericidal/bacteriostatic functions against a variety of pathogens. Among the AIIMs, sheep ?-defensin-1 (SBD-1) is one of the most potent. Even though the SBD-1 is an important AIIM and it is regulated closely by estrogenic hormone, the regulation mechanism of 17?-estradiol has not been clearly established. We investigated the effects of E2 and agonist or inhibitor on ovine oviduct epithelial cells in regard to SBD-1 expression using reverse transcription quantitative PCR (RT-qPCR). In addition, three different pathways were inhibited separately or simultaneously to confirm the effect of different inhibitors in the regulation mechanism. Results 17beta-estradiol (E2) induced release of SBD-1 in ovine oviduct epithelial cells. SBD-1 expression was mediated through G-protein-coupled receptor 30 (GPR30) and Estrogen Receptors (ERs) activation in ovine oviduct epithelial cell. Inhibition of gene expression of protein kinase A (PKA), protein kinase C (PKC), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-?B) led to a decreased SBD-1 expression. Conclusions Taken together, E2-induced up-regulation of SBD-1 expressions were GPR30-dependent during prophase and ERs-dependent during later-stage in ovine oviduct epithelial cells, and we assume that the effect was completed by the PKA, PKC, and NF-?B pathways simultaneous.

2012-01-01

7

17beta-estradiol does not protect cerebellar granule cells from excitotoxicity or apoptosis.  

PubMed

Mounting evidences have suggested that 17beta-estradiol (E2) could have a neuroprotective action in the CNS. In the present study, we wanted to study whether this estrogen was able to protect cerebellar granule cells (CGCs) from apoptosis or excitotoxicity. Our results suggest that E2 has no anti-apoptotic effect in CGCs cultures. The lack of phosphoinositide 3-kinase/Akt pathway activation in CGCs cultures could be on the basis of the failure of estradiol to protect CGCs from potassium-deprivation and ceramide-mediated apoptosis. Moreover, E2 does not protect CGCs from glutamate-mediated death despite activating the extracellular signal regulated kinase kinase/extracellular signal regulated kinase pathway, which suggests that extracellular signal regulated kinase kinase/extracellular signal regulated kinase pathway activation is not sufficient to sustain an estrogen-mediated neuroprotective effect in CGCs cultures. By contrast, we found that the estrogen had a significant neuroprotective effect against hydrogen peroxide-mediated neuronal death. This effect was due to the antioxidant properties of the chemical structure of estradiol, as the biological inactive isomer 17alpha-estradiol was also able to reduce hydrogen peroxide-mediated neuronal death. PMID:17596211

Miñano, Alfredo; Cerbón, Marco Antonio; Xifró, Xavier; Malagelada, Cristina; Aguilera, José; Rodríguez-Alvarez, José

2007-07-01

8

17beta-estradiol protects male mice from cuprizone-induced demyelination and oligodendrocyte loss.  

PubMed

In addition to regulating reproductive functions in the brain and periphery, estrogen has tropic and neuroprotective functions in the central nervous system (CNS). Estrogen administration has been demonstrated to provide protection in several animal models of CNS disorders, including stroke, brain injury, epilepsy, Parkinson's disease, Alzheimer's disease, age-related cognitive decline and multiple sclerosis. Here, we use a model of toxin-induced oligodendrocyte death which results in demyelination, reactive gliosis, recruitment of oligodendrocyte precursor cells and subsequent remyelination to study the potential benefit of 17beta-estradiol (E2) administration in male mice. The results indicate that E2 partially ameliorates loss of oligodendrocytes and demyelination in the corpus callosum. This protection is accompanied by a delay in microglia accumulation as well as reduced mRNA expression of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNFalpha), and insulin-like growth factor-1 (IGF-1). E2 did not significantly alter the accumulation of astrocytes or oligodendrocyte precursor cells, or remyelination. These data obtained from a toxin-induced, T cell-independent model using male mice provide an expanded view of the beneficial effects of estrogen on oligodendrocyte and myelin preservation. PMID:20347981

Taylor, Lorelei C; Puranam, Kasturi; Gilmore, Wendy; Ting, Jenny P-Y; Matsushima, Glenn K

2010-03-27

9

Gene expression profiling of 17beta-estradiol and genistein effects on mouse thymus.  

PubMed

Estrogen regulates thymic development and involution and modulates immune function. Despite its critical role in thymus, as well as in autoimmune disorders, the mechanism by which estrogen affects the thymus is not well understood. We previously reported that the estrogenic soy isoflavone genistein, as well as 17beta-estradiol (E2), could induce thymic involution, but genistein effects were only partially mediated through estrogen receptors. To provide insights into mechanisms of estrogenic effects in the thymus, we investigated thymic gene expression changes induced by E2 (125 ng/day) and genistein (1500 ppm in feed) in weanling mice using high-density DNA arrays. We identified several E2-responsive genes involved in thymic development and thymocyte signaling during selection and maturation. Functional characterization indicated effects on genes involved in transcription, apoptosis, and the cell cycle. This study also identified changes in several E2-regulated transcripts essential to maintain immune self-tolerance. E2 upregulated more genes than genistein, while genistein downregulated more genes than E2. Though each treatment regulated several genes not altered by the other, there was considerable overlap in the genes regulated by E2 and genistein. Changes in transcription factors and cell cycle factors were consistent with decreases in cell proliferation induced by both genistein and E2. As indicated by the regulation of non-E2-responsive genes, genistein also induced unique effects through non-estrogenic mechanisms. The specific downregulation of the CD4 coreceptor transcript by genistein was consistent with the decline of CD4+ thymocytes in genistein-treated mice in our previous study. This is the first study identifying E2 and genistein target genes in the thymus. These findings provide new mechanistic insights toward explaining estrogen action on thymocyte development, selection, and maturation, as well as the effects of genistein on prenatal and neonatal thymic development and function. PMID:15947025

Selvaraj, Vimal; Bunick, David; Finnigan-Bunick, Carrol; Johnson, Rodney W; Wang, Huixia; Liu, Lei; Cooke, Paul S

2005-06-09

10

Endosulfan modulates estrogen-dependent genes like a non-uterotrophic dose of 17beta-estradiol.  

PubMed

The estrogenic activity of environmentally relevant doses of endosulfan was investigated using an animal model. Ovariectomized adult rats were injected once a day for 3 days with sesame oil (control), 0.02mg/kg/day 17beta-estradiol (an uterotrophic dose; UE(2)), 0.0002mg/kg/day 17beta-estradiol (a non-uterotrophic dose; NUE(2)), or 0.006, 0.06, 0.6 or 6mg/kg/day endosulfan. After 24h of treatment, the uteri were weighed (uterotrophic assay) and the luminal epithelial cell height (LECH) and progesterone receptor (PR), and estrogen receptor alpha (ERalpha) protein levels were measured. PR, ERalpha, and complement factor-3 (C3) mRNAs were evaluated using real-time PCR. Uterine weight and LECH were only increased in UE(2)-treated rats. PR, ERalpha and C3 expression levels were modified in most of the endosulfan-treated groups, showing an identical pattern of expression to the NUE(2)-group. Our results show that the pesticide endosulfan mimics non-uterotrophic E(2) actions, strengthening the hypothesis that endosulfan is a widespread xenoestrogen. PMID:18790044

Varayoud, Jorgelina; Monje, Lucas; Bernhardt, Tania; Muñoz-de-Toro, Mónica; Luque, Enrique H; Ramos, Jorge G

2008-08-23

11

Persistence and Fate of 17beta-estradiol and testosterone in agricultural soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Steroidal hormones are constantly released into the environment by man-made and natural sources. The goal of this study was to examine the persistence and fate of 17beta-estradiol and testosterone, the two primary natural hormones. Incubation experiments were conducted under aerobic and anaerobic co...

12

Assessing the effects of exposure timing on biomarker expression using 17beta-estradiol.  

PubMed

Temporal and spatial variability in estrogenicity has been documented for many treated wastewater effluents with the consequences of this variability on the expression of biomarkers of endocrine disruption being largely unknown. Laboratory exposure studies usually utilize constant exposure concentrations which may produce biological effects that differ from those observed in organisms exposed in natural environments. In this study, we investigated the effects of differential timing of exposures with 17beta-estradiol (E2) on a range of fathead minnow biomarkers to simulate diverse environmentally relevant exposure profiles. Two 21-day, replicate experiments were performed exposing mature male fathead minnows to E2 at time-weighted mean concentrations (similar average exposure to the contaminant during the 21-day exposure period; 17ng E2/L experiment 1; 12ng E2/L experiment 2) comparable to E2 equivalency values (EEQ) reported for several anthropogenically altered environments. A comparable time-weighted mean concentration of E2 was applied to five treatments which varied in the daily application schema: E2 was either applied at a steady rate (ST), in a gradual decreasing concentration (HI), a gradual increasing concentration (LO), applied intermittently (IN), or at a randomly varying concentration (VA). We assessed a range of widely used physiological (vitellogenin mRNA induction and plasma concentrations), anatomical (body and organ indices, secondary sex characteristics, and histopathology), and behavioral (nest holding) biomarkers reported to change following exposure to endocrine active compounds (EACs). All treatments responded with a rise in plasma vitellogenin concentration when compared with the ethanol carrier control. Predicatively, vitellogenin mRNA induction, which tracked closely with plasma vitellogenin concentrations in most treatments was not elevated in the HI treatment, presumably due to the lack of E2 exposure immediately prior to analysis. The ability of treatment male fish to hold nest sites in direct competition with control males was sensitive to E2 exposure and did yield statistically significant differences between treatments and carrier control. Other biological endpoints assessed in this study (organosomatic indices, secondary sex characteristics) varied little between treatments and controls. This study indicates that a broad suite of endpoints is necessary to fully assess the biological consequences of fish exposure to estrogens and that for at least field studies, a combination of vitellogenin mRNA and plasma vitellogenin analysis are most promising in deciphering exposure histories of wild-caught and caged fishes. PMID:20005582

Hyndman, K M; Biales, A; Bartell, S E; Schoenfuss, H L

2009-11-14

13

17beta-Estradiol levels in male zebra finch brain: combining Palkovits punch and an ultrasensitive radioimmunoassay.  

PubMed

Local aromatization of testosterone into 17beta-estradiol (E(2)) is often required for the physiological and behavioral actions of testosterone. In most vertebrates, aromatase is expressed in a few discrete brain regions. While many studies have measured brain aromatase mRNA or activity, very few studies have measured brain E(2) levels, particularly in discrete brain regions, because of technical challenges. Here, we used the Palkovits punch technique to isolate 13 discrete brain nuclei from adult male zebra finches. Steroids were extracted via solid phase extraction. E(2) was then measured with an ultrasensitive, specific and precise radioimmunoassay. Our protocol leads to high recovery of E(2) (84%) and effectively removes interfering brain lipids. E(2) levels were high in aromatase-rich regions such as caudal medial nidopallium and hippocampus. E(2) levels were intermediate in the medial preoptic area, ventromedial nucleus of the hypothalamus, lateral and medial magnocellular nuclei of anterior nidopallium, nucleus taeniae of the amygdala, and Area X. E(2) levels were largely non-detectable in the cerebellum, HVC, lateral nidopallium and optic lobes. Importantly, E(2) levels were significantly lower in plasma than in the caudal medial nidopallium. This protocol allows one to measure E(2) in discrete brain regions and potentially relate local E(2) concentrations to aromatase activity and behavior. PMID:20144613

Charlier, Thierry D; Po, Kelvin W L; Newman, Amy E M; Shah, Amit H; Saldanha, Colin J; Soma, Kiran K

2010-02-06

14

Rapid and sensitive detection of 17beta-estradiol in environmental water using automated immunoassay system with bacterial magnetic particles.  

PubMed

A fully automated immunoassay of 17beta-estradiol (E2) was performed using anti-E2 monoclonal antibody immobilized on bacterial magnetic particles (AntiE2-BMPs) and alkaline phosphatase-conjugated E2 (ALP-E2). E2 concentration in environmental water samples was evaluated by decrease in luminescence based on competitive reaction. A linear correlation between the luminescence intensity and E2 concentration was obtained between 0.5 and 5 ppb. The minimum detectable concentration of E2 was 20 ppt. All measurement steps were done within 0.5 h. The analysis of environmental water samples by a commercially available ELISA kit and the BMP-based immunoassay gave good correlation plots with a correlation efficient of 0.992. These results suggest that the fully automated system using the BMP-based immunoassay has some advantages in the high rapidity and sensitivity of the measurement. This system will enable us to determine low E2 concentrations without sample condensation. PMID:15129724

Tanaka, Tsuyoshi; Takeda, Hajime; Ueki, Fumiko; Obata, Kimimichi; Tajima, Hideji; Takeyama, Haruko; Goda, Yasuhiro; Fujimoto, Shigeru; Matsunaga, Tadashi

2004-03-01

15

Direct effects of 17 beta-estradiol on trabecular bone in ovariectomized rats.  

PubMed Central

High-affinity nuclear binding sites for 17 beta-estradiol (17 beta E2) were recently found in bone cells; however, the mechanism by which estrogen exerts its effect on bone in vivo is still unknown. To study if estrogen acts on bone directly, we used an experimental model in which test substances are infused locally into rat femur trabecular bone. Sprague-Dawley rats weighing 150-160 g were ovariectomized (OVX) and 14 days later a polyethylene tube (1 mm in diameter) connected to an Alzet osmotic minipump was implanted into the distal femur 9 mm from the joint. 17 beta E2 (24 microliters/day at 0.01-1 nM), 17 alpha-estradiol (17 alpha E2) (24 microliters/day at 1 nM), or phosphate-buffered saline (NaCl, 8 g/liter; KCl, 0.2 g/liter; KH2PO4, 0.2 g/liter; Na2HPO4.7H2O, 2.16 g/liter) was infused for 8 days. The contralateral limb remained intact. Animals were sacrificed and bones were examined by histomorphometry. Ovariectomy caused a 50% loss in trabecular bone volume (TBV) in the secondary spongiosa (from 20.3% +/- 1.7% to 9.6% +/- 1.1%; mean +/- SEM), a 2-fold increase in osteoclast number (to 4.0 +/- 0.4 per mm), a 3-fold increase in relative resorption surfaces (to 24.8% +/- 2.9%), a 9-fold increase in osteoblast number (to 11.3 +/- 2.1 per mm), and an 8-fold increase in relative osteoid surface (to 9.6% +/- 1.7%). The local infusion of 17 beta E2 for 8 days into OVX rats (i) restored the TBV dose dependently to 75% and 85% of control (non-OVX) levels, at 0.1 nM and 1 nM 17 beta E2, respectively; (ii) decreased osteoclast number and the relative resorption surface to control (non-OVX) levels; and (iii) further increased osteoblast number and the relative osteoid surface dose dependently (by 5-fold at 1 nM 17 beta E2). Phosphate-buffered saline infusion was without effect. Infusion of 17 alpha E2 had no effect on TBV, osteoclast number, or resorption surface but increased slightly the osteoblast number and the osteoid surface. Its potency was 1/100 that of 17 beta E2. The local infusion of 17 beta E2 or 17 alpha E2 had no effect on body or uterine weight. We conclude from these findings that estrogen delivered directly to the bone of OVX rats in vivo at 2.4 and 24 fmol/day acted locally to inhibit bone resorption and stimulate bone formation. Images

Takano-Yamamoto, T; Rodan, G A

1990-01-01

16

Sex hormone concentrations and gonad histology in brown trout (Salmo trutta) exposed to 17beta-estradiol and bisphenol A.  

PubMed

The impact of 17beta-estradiol (E2) and bisphenol A (BPA) on steroid hormone levels and gonad development in brown trout (Salmo trutta) was determined. Exposure took place from 0 to 63 days post-fertilisation (dpf) and gonad development was followed till 400 dpf. The onset of xenoestrogen metabolism was examined by measurements of whole body concentrations of bisphenol A (BPA) and its conjugation product bisphenol A glucuronic acid (BPAGA). Exposure to 500 ng E2/l led to an increase in E2 levels in the embryos and fry while 10 ng E2/l did not. Metabolic conversion of BPA to BPAGA began during the first weeks of embryonic development. Few consistent effects were found on the sex differentiation of the brown trout. Only one intersex fish (4.5%) was found among male fish at 400 dpf exposed to 500 ng E2/l. Females with male germ cells among the normally developing oocytes were observed in all groups (in up to 50% of the female fish, independently of exposure regime). The fact that exposure to 500 ng E2/l only caused subtle effects in a small number of individuals indicates that exposure during early life stages results in little to no induction of endocrine disruption in brown trout. PMID:18320304

Bjerregaard, Lisette Bachmann; Lindholst, Christian; Korsgaard, Bodil; Bjerregaard, Poul

2008-03-05

17

Differential expression of CYP102 in Bacillus megaterium by 17-beta-estradiol and 4-sec-butylphenol.  

PubMed

Previously we have reported the induction of CYP102 in Bacillus megaterium by 17beta-estradiol (E2) and 4-sec-butylphenol (4-sBP). Electrophoretic mobility shift assay analyses demonstrated that E2 and 4-sBP both cause a dose-dependent disassociation of the Bm3R1 repressor protein from its binding site on the operator sequence of the CYP102 gene. Equimolar combinations of E2 and 4-sBP demonstrated additive induction of CYP102 compared to equivalent samples of E2 and 4-sBP added alone. Two gene constructs were used in this investigation. One construct designated BMC143 contained the entire regulatory region of CYP102. The other gene construct, designated BMA45, had the "Barbie box" sequence deleted. While the induction of CYP102 by 4-sBP was much higher in the BMC 143 construct, E2 induced CYP102 in both constructs to the same extent. This difference in induction of CYP102 by these two inducers indicates that they act at different sites, either on the Bm3R1 repressor protein or on positive regulatory sites, or that they act, in part, through different mechanisms. PMID:12480527

Rowley, Christopher W; Rajnarayanan, Rajendram V; Hopkins, Nancy E; Alworth, William L

2003-01-01

18

Sex differentiation and vitellogenin and 11-ketotestosterone levels in chub, Leuciscus cephalus L., exposed to 17 beta-estradiol and testosterone during early development.  

PubMed

The effects of 17 beta-estradiol (E(2)) and testosterone (T) singly and in combination were tested on juvenile chub (Leuciscus cephalus L.). Vitellogenin (VTG) and 11-ketotestosterone (11-KT) were determined by ELISA in whole body homogenates and the gonads were examined histologically. Testosterone and estradiol, in combination, significantly increased whole body VTG (p < 0.01), but not 11-KT, compared to controls and the T treated groups. The only intersex observed (1/80) was in the combined treatment group. We suggest that VTG measured in whole body homogenates could be used to determine the effects of exogenous steroids in juvenile chub. PMID:18953473

Zlábek, Vladimír; Randák, T; Kolárová, J; Svobodová, Z; Kroupová, H

2008-10-25

19

Molecularly imprinted micro and nanospheres for the selective recognition of 17beta-estradiol.  

PubMed

A one-step precipitation polymerization procedure for the synthesis of molecularly imprinted polymers selective for 17beta-estradiol yielding imprinted micro and nanospheres was developed in this study and compared to templated materials obtained by conventional bulk polymerization. The polymer particles prepared by precipitation polymerization exhibited a regular spherical shape at the micro and nanoscale with a high degree of monodispersity. Moreover, the influence of the polymerization temperature, and the ratio of functional monomer to cross-linker on the size of the obtained particles was investigated. The selectivity of the imprinted micro and nanospheres was evaluated by HPLC analysis and via radioligand binding assays. HPLC separation experiments revealed that the imprinted microspheres provide higher or similar affinity to the template in contrast to imprinted polymers prepared by conventional bulk polymerization or synthesized by multi-step swelling/polymerization methods. The dimensions of the imprinted nanospheres facilitate suspension in solution rendering them ideal for binding assay applications. Results from saturation and displacement assays prove that the imprinted nanospheres exhibit superior specific affinity to the target molecule in contrast to control materials. The binding properties of the nanospheres including binding isotherms and affinity distribution were studied via Freundlich isotherm affinity distribution (FIAD) analysis. Moreover, release experiments show that 70% of rebound 17beta-estradiol was released from the imprinted nanospheres within the first 2 h, while more intimately bound 17beta-estradiol molecules (approx. 16%) were released in the following 42 h. Fitting Brunnauer-Emmet-Teller (BET) multi-point adsorption isotherms to the obtained results indicated that the micro and nanospheres are characterized by a comparatively homogenous and narrow distribution of mesopores in contrast to the corresponding bulk polymers. PMID:16326090

Wei, Shuting; Molinelli, Alexandra; Mizaikoff, Boris

2005-12-02

20

Topical application of 17beta-estradiol increases extracellular matrix protein synthesis by stimulating tgf-Beta signaling in aged human skin in vivo.  

PubMed

To investigate the effects of topically applied 17beta-estradiol on the expression of extracellular matrix proteins in aged human skin, 17beta-estradiol (0.01%) and its vehicle (70% propylene glycol, 30% ethanol) were applied to aged (68-82 y, eight females and five males) human buttock skin under occlusion for 2 wk (three times per week). Topical 17beta-estradiol was found to increase the expression of type 1 procollagen mRNA and protein significantly in human aged skin in vivo. In addition, metalloproteinase (MMP-1 protein levels were reduced by topical 17beta-estradiol. The expressions of TGF-beta1, TGF-beta type II receptor, and Sma and Mad related (Smad)3 were increased by topical 17 beta-estradiol in aged human skin, and TGF-beta1 neutralizing antibody inhibited 17beta-estradiol-induced procollagen synthesis in cultured fibroblasts. We also found that the expressions of tropoelastin and fibrillin-1 mRNA and protein, and elastic fibers in aged skin were also increased by topical 17beta-estradiol. Topical 17beta-estradiol also increased keratinocyte proliferation and the epidermal thickness in aged human skin. We also observed the same effects of topical 17beta-estradiol in young skin. In conclusion, our results suggest that topical 17beta-estradiol treatment may improve the cutaneous function of aged human skin by improving the connective tissue and increasing epidermal thickness. PMID:15955089

Son, Eui Dong; Lee, Jin Young; Lee, Serah; Kim, Mi Sun; Lee, Byeong Gon; Chang, Ih Seoup; Chung, Jin Ho

2005-06-01

21

Protein profiling and transcript expression levels of heat shock proteins in 17beta-estradiol-treated human MCF-7 breast cancer cells.  

PubMed

Using proteomics, proteins regulated by 17beta-estradiol (E2) were identified in human MCF-7 breast cancer cells; 26 proteins including heat shock proteins (Hsps) were differentially regulated by E2 in cells cultured in serum-free condition. When the transcript levels of these proteins and another Hsps were measured by real-time PCR, the transcripts encoding 6 proteins (Hsp56, Hsp90alpha, Hsp110, protein disulfide isomerase related protein, XTP3-transactivated protein A and stathmin 1) were significantly up-regulated and that encoding aminoacylase 1 was down-regulated by E2 in cells cultured with or without serum. The protein profiling and transcript expression patterns of E2-regulated proteins including Hsps in MCF-7 cells suggested the involvement of these proteins in breast carcinogenesis. Proteins (or transcripts) whose expression pattern is altered by E2 might be potent targets for treating breast cancer patients. PMID:16962797

Lee, Su-Ui; Kim, Bum Tae; Min, Yong Ki; Kim, Seong Hwan

2006-08-07

22

Primary induction of vitellogenin mRNA in the rooster by 17beta-estradiol.  

PubMed Central

We have studied the kinetics of vitellogenin mRNA accumulation in rooster liver after a primary injection of 17beta-estradiol. The levels of vitellogenin mRNA have been determined both by hybridization of total cellular RNA to vitellogenin cDNA and by translation of vitellogenin mRNA in a wheat germ cell-free system. The results obtained by both methods of analysis are in good agreement and indicate that vitellogenin mRNA is present in the liver of normal roosters at a level of 0-5 molecules per liver cell and increases in amount during the 3 days following injection of estrogen, reaching a level of almost 6000 molecules per cell at the peak of the response. The level of vitellogenin mRNA declined exponentially during the next 14 days with a half-life of 29 hr, reaching a level of less than 10 molecules per cell at 17 days after injection of the hormone. The levels of vitellogenin mRNA after stimulation with estrogen have been correlated with the in vivo rate of synthesis of the vitellogenin polypeptide. The results indicate that the rate of vitellogenin synthesis is closely correlated with the level of vitellogenin mRNA. On the basis of these findings, we conclude that vitellogenin mRNA does not exist in the liver in an untranslated form after withdrawal from estrogen.

Burns, A T; Deeley, R G; Gordon, J I; Udell, D S; Mullinix, K P; Goldberger, R F

1978-01-01

23

17beta-estradiol and progesterone prevent cuprizone provoked demyelination of corpus callosum in male mice.  

PubMed

Sex hormones, for example, estrogen and progesterone, are thought to affect and delay progression of multiple sclerosis (MS) in pregnant women. Although both steroid hormones are neuroprotective in the brain and elevated during pregnancy, only estrogen was tested in clinical trials. To evaluate the role of 17beta-estradiol (E) and progesterone (P) in prevention demyelination, young adult male mice were fed with cuprizone for a defined time interval and simultaneously treated with steroids by repeated injections into the neck region. The status of myelination was analyzed by magnetic resonance imaging and conventional histological staining. The individual application of E and P resulted only in a moderate prevention of demyelination in the corpus callosum (CC). The combined treatment with both steroid hormones counteracted the process of demyelination. Expression of the mature (PLP and MBP) and premature (PDGF-alpha-R) oligodendrocyte markers were significantly increased after hormone application in the affected CC. In addition, both hormones stimulated astrogliosis and the expression of IGF-1. Microglial invasion in demyelinated CC was pronounced and additionally localized in the midline of CC after hormone treatment. These data show that sex steroids can protect the brain from demyelination and stimulate remyelination. It appears that only the administration of both hormones is fully effective. The beneficial steroid effect requires interactions with oligodendrocytes possibly by preventing their degeneration or recruitment from precursor cells which are stimulated to remyelinated fibers. The positive hormonal influence on myelination in the CNS may be a future therapeutically strategy for the treatment of MS. PMID:19031445

Acs, Peter; Kipp, Markus; Norkute, Akvile; Johann, Sonja; Clarner, Tim; Braun, Alena; Berente, Zoltan; Komoly, Samuel; Beyer, Cordian

2009-06-01

24

17beta-estradiol treatment decreases steroidogenic enzyme messenger ribonucleic acid levels in the rainbow trout testis.  

PubMed

In fish, estrogens are well known for their involvement in ovarian differentiation and have been shown to be very potent feminizing agents when administrated in vivo during early development. However, the mechanism of action of exogenous estrogens is poorly understood. We report here on the feminizing effects of estrogen treatment on the testicular levels of some steroidogenic enzyme messenger RNAs [mRNAs; cholesterol side-chain cleavage (P450scc), 17-hydroxylase/lyase (P450c17), 3beta-hydroxysteroid dehydrogenase (3betaHSD), 11beta-hydroxylase (P45011beta), and aromatase (P450aro)] in the rainbow trout, Oncorhynchus mykiss. Treatment was carried out by dietary administration of 17beta-estradiol (E(2); dosage of 20 mg/kg diet) to a genetically all male population. Steroidogenesis in the differentiating testis was demonstrated to be strongly altered by E(2), as this treatment resulted in considerable decrease in P450c17, 3betaHSD, and P45011beta mRNAs after only 10 days of treatment. In contrast, P450scc and P450aro mRNA levels were unaffected by E(2), with P450scc mRNA levels remaining unaltered and P450aro not stimulated by this feminizing estrogen treatment. To better characterize this E(2) effect, the same treatment was applied on postdifferentiating males, and roughly the same expression pattern was detected with a considerable decrease in testicular P450c17, 3betaHSD, and P45011beta mRNAs and a significant, but reduced, decrease in P450scc mRNA. In the interrenal, these steroidogenic enzyme mRNAs were not significantly affected by this E(2) treatment, except for a slight, but significant, decrease in P450scc mRNA. These results clearly demonstrate that estrogens have profound effects on testicular steroidogenesis and that they are acting specifically on the testis by decreasing mRNA steady state levels of many steroidogenic enzyme genes. The decrease in P45011beta mRNA, and thus inhibition of the synthesis of testicular 11-oxygenated androgens, may be an important step required for the active feminization of these genetic males. PMID:11316749

Govoroun, M; McMeel, O M; Mecherouki, H; Smith, T J; Guiguen, Y

2001-05-01

25

17beta-Estradiol reduces cortical lesion size in the glutamate excitotoxicity model by enhancing extracellular lactate: a new neuroprotective pathway.  

PubMed

Estrogens play an important role in neuronal function and in protecting neurones in the cerebral cortex against pathological conditions. An in vivo model of glutamate excitotoxicity in which glutamate is applied to the cortex of rats through a microdialysis probe has been used to investigate the neuroprotective processes initiated by 17beta-estradiol. Rats were pre-treated with 17beta-estradiol (i.v.) before local application of 100 mM glutamate into the cortex through a microdialysis probe. Pre-treatment with 17beta-estradiol significantly reduced the size of the glutamate-induced cortical lesion. In the cortical microdialysates collected from the probe, a peak of lactate was observed immediately after glutamate application. After 17beta-estradiol pre-treatment this peak of lactate was significantly higher with estradiol than without 120 min after glutamate application, reaching 700% basal level at the end of measurement. The level of extracellular glucose was markedly decreased with and without 17beta-estradiol pre-treatment. Local blockage of neuronal lactate transporters with alpha-cyano-4-hydroxycinnamate (4-CIN) completely abolished the neuroprotective effect of 17beta-estradiol and induced a larger cortical lesion. An accumulation of extracellular lactate was observed after inhibition of the lactate transporters suggesting that transport of lactate into neurones is necessary for the neuroprotective effect of 17beta-estradiol. The anti-estrogen tamoxifen also abolished the neuroprotective effect of 17beta-estradiol on the lesion size and inhibited the production of lactate. These results suggest a new neuroprotective mechanism of 17beta-estradiol by activating glutamate-stimulated lactate production, which is estrogen receptor-dependent. PMID:11368971

Mendelowitsch, A; Ritz, M F; Ros, J; Langemann, H; Gratzl, O

2001-05-18

26

Local Delivery of 17-Beta-Estradiol Modulates Collagen Content in Coronary Porcine Arteries after PTCA and Stent Implantation  

Microsoft Academic Search

Background: Percutaneous transluminal coronary angioplasty (PTCA) and stent implantation are associated with intimal hyperplasia and extracellular matrix (ECM) accumulation, resulting in restenosis. We showed that local delivery of 17-beta-estradiol (17?E) reduced restenosis following PTCA and stent implantation by 47 and 23%, respectively. Because estrogens decreased type I and type III collagen synthesis in vitro, we hypothesized that local delivery of

Pedro Geraldes; Pascale Geoffroy; Isabelle Cloutier; Martin G. Sirois; Jean-François Tanguay

2008-01-01

27

Trace LC/MS/MS quantitation of 17beta-estradiol as a biomarker for selective estrogen receptor modulator activity in the rat brain.  

PubMed

A sensitive LC/MS/MS method has been developed by derivatization of 17beta-estradiol (E2) with dansyl chloride to quantitate 17beta-E2 in female rat serum. The use of E2-d(5) minimized interferences from endogenous 17beta-E2 in order to achieve a limit of quantitation (LOQ) of 2.5 pg/ml using 150 microl of female rat serum. The recovery of the dansyl derivative was 95% or greater in quality control samples. The intra and interday assay precision was better than 8.2 and 6.2%, respectively, with accuracies ranging from 97 to 101% in the quality control samples. The assay was used for the quantitation of serum E2 as a biomarker for the estrogen receptor (ER) antagonist activity of small molecule SERMs (selective estrogen receptor modulators) in the female rat brain. The study revealed that a statistically significant upregulation of serum 17beta-E2 occurred for rats dosed with SERMs that are known to penetrate the brain and disrupt the hypothalamic-pituitary-ovarian (HPO) axis. Variations in 17beta-E2 in ascending dose studies also correlated with the corresponding trends in CYP17a1 levels, an mRNA biomarker for ovarian hyperstimulation. This biomarker assay has provided a useful screen for medicinal chemistry optimization to produce SERMs that do not interfere with negative feedback of estrogens on the brain and for biological hypothesis testing. PMID:19882750

Petucci, Chris; Lloyd, Tom; Harris, Heather A; Zhang, Xiaochun; Chennathukuzhi, Vargheese M; Mekonnen, Belew; Cai, Yanxuan

2010-01-01

28

17 beta-estradiol induces spermatogonial proliferation through mitogen-activated protein kinase (extracellular signal-regulated kinase 1/2) activity in the lizard (Podarcis s. sicula).  

PubMed

There are always more evidences indicating that 17beta-estradiol (E(2)) is necessary for normal male fertility. We have used a nonmammalian vertebrate model (the lizard Podarcis s. sicula) to investigate the regulation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) activity in the testis during the annual sexual cycle and to study whether E(2) exerts a role in the spermatogenesis through ERK1/2 activity. Immunocytochemistry analysis shows that ERK1/2 proteins are present in the nucleus of the spermatogonia (SPG), and in primary (I) spermatocytes (SPC). The annual E(2) profile shows a progressive increase during the active spermatogenesis (from April to June) and a peak in the month of August (spermatogonial mitosis). In parallel, ERK1/2 (molecular weight 44 and 42 kDa, respectively) are highly phosphorylated during the period of active spermatogenesis and in post-refractory period (August) compared with the winter stasis (from November to March). Present results demonstrate that E(2) treatment induces spermatogonial proliferation, possibly via the activation of ERK1/2, and this effect is counteracted by the antiestrogen ICI 182-780. PMID:11803558

Chieffi, Paolo; Colucci D'Amato, Luca; Guarino, Fabio; Salvatore, Gaetano; Angelini, Francesco

2002-02-01

29

Caveolin 1 is required for the activation of endothelial nitric oxide synthase in response to 17beta-estradiol.  

PubMed

Evidence suggests that estrogen mediates rapid endothelial nitric oxide synthase (eNOS) activation via estrogen receptor-a (ERalpha) within the plasma membrane of endothelial cells (EC). ERalpha is known to colocalize with caveolin 1, the major structural protein of caveolae, and caveolin 1 stimulates the translocation of ERalpha to the plasma membrane. However, the role played by caveolin 1 in regulating 17beta-estradiol-mediated NO signaling in EC has not been adequately resolved. Thus, the purpose of this study was to explore how 17beta-estradiol stimulates eNOS activity and the role of caveolin 1 in this process. Our data demonstrate that modulation of caveolin 1 expression using small interfering RNA or adenoviral gene delivery alters ERalpha localization to the plasma membrane in EC. Further, before estrogen stimulation ERalpha associates with caveolin 1, whereas stimulation promotes a pp60(Src)-mediated phosphorylation of caveolin 1 at tyrosine 14, increasing ERalpha-PI3 kinase interactions and disrupting caveolin 1-ERalpha interactions. Adenoviral mediated overexpression of a phosphorylation-deficient mutant of caveolin (Y14FCav) attenuated the ERalpha/PI3 kinase interaction and prevented Akt-mediated eNOS activation. Furthermore, Y14FCav overexpression reduced eNOS phosphorylation at serine1177 and decreased NO generation after estrogen exposure. Using a library of overlapping peptides we identified residues 62-73 of caveolin 1 as the ERalpha-binding site. Delivery of a synthetic peptide based on this sequence decreased ERalpha plasma membrane translocation and reduced estrogen-mediated activation of eNOS. In conclusion, caveolin 1 stimulates 17beta-estradiol-induced NO production by promoting ERalpha to the plasma membrane, which facilitates the activation of the PI3 kinase pathway, leading to eNOS activation and NO generation. PMID:20610538

Sud, Neetu; Wiseman, Dean A; Black, Stephen M

2010-07-07

30

Organochlorine compounds in liver and concentrations of vitellogenin and 17beta-estradiol in plasma of sea bass fed with a commercial or with a natural diet.  

PubMed

Results from previous experiments directed to determine the effect of different nutritional factors or the effect of xenobiotics on hormonal control of reproduction, lead to the hypothesis that hormonal perturbations repeatedly observed in sea bass (Dicentrarchus labrax) broodstock feeding commercial diets could have been caused by the presence of aryl hydrocarbon receptor (AhR) ligands, such as dioxins, furans and polychlorinated biphenyls (PCBs) in the diet. To evaluate this hypothesis, dioxins and related compounds were analysed in liver of female sea bass fed with a commercial or with a natural diet consisting of trash fish (bogue, Boops boops), and concentrations of vitellogenin (VTG) and 17beta-estradiol (E2) were determined in plasma obtained previously in monthly samplings of these animals. As observed in other experiments, females fed with a commercial diet exhibited lower VTG and higher E2 plasma levels than females fed with the natural diet. In liver, sea bass fed with the commercial diet exhibited a profile clearly dominated by high-chlorinated dioxins while in fish fed with the natural diet this profile was dominated by low chlorinated furans. However, typical AhR ligands, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin showed no differences between groups or, as is the case of planar PCBs, showed higher concentrations in the liver of fish fed with the natural diet. These results do not permit to explain the observed hormonal alterations by a possible antiestrogenic effect caused by dioxins and related compounds. PMID:16213605

Navas, J M; Merino, R; Jiménez, B; Rivera, J; Abad, E; Zanuy, S; Carrillo, M

2005-10-06

31

A computational model of the hypothalamic-pituitary-gonadal axis in male fathead minnows exposed to 17alpha-ethinylestradiol and 17beta-estradiol.  

PubMed

Estrogenic chemicals in the aquatic environment have been shown to cause a variety of reproductive anomalies in fish including full sex reversal, intersex, and altered population sex ratios. Two estrogens found in the aquatic environment, 17alpha-ethinylestradiol (EE(2)) and 17beta-estradiol (E(2)), have been measured in wastewater treatment effluents and have been shown to cause adverse effects in fish. To further our understanding of how estrogen exposure affects reproductive endpoints in the male fathead minnow (FHM, Pimephales promelas), a physiologically based computational model was developed of the hypothalamic-pituitary-gonadal (HPG) axis. Apical reproductive endpoints in the model include plasma steroid hormone and vitellogenin concentrations. Using Markov chain Monte Carlo simulation, the model was calibrated with data from unexposed FHM, and FHM exposed to EE(2) and E(2). Independent experimental data sets were used to evaluate model predictions. We found good agreement between our model predictions and a variety of measured reproductive endpoints, although the model underpredicts unexposed FHM reproductive endpoint variances, and overpredicts variances in estrogen-exposed FHM. We conclude that this model provides a robust representation of the HPG axis in male FHM. PMID:19357070

Watanabe, Karen H; Li, Zhenhong; Kroll, Kevin J; Villeneuve, Daniel L; Garcia-Reyero, Natàlia; Orlando, Edward F; Sepúlveda, Maria S; Collette, Timothy W; Ekman, Drew R; Ankley, Gerald T; Denslow, Nancy D

2009-04-08

32

Effects of soy isoflavones on 17beta-estradiol-induced proliferation of MCF-7 breast cancer cells.  

PubMed

Based on the results of in vitro-experiments in practically estrogen-free media and in the absence of estrogen-beta receptors, soy isoflavones have been suspected to enhance proliferation of MCF-7 breast cancer cells. In this study the effects of soy isoflavones on MCF-7 cells were investigated in the presence and absence of estrogen, directly and in a metabolized form by testing sera of postmenopausal women supplemented with isoflavones. First, three concentrations of isoflavones (0.1, 1 and 10 mumol/l) were tested at increasing levels of 17-beta-estradiol (<10 pM, 50, 100 and 500 pM). Next, blood sera from women supplemented for two weeks either with 200mg isoflavones or with 2 mg 17-beta-estradiol per day, or the combination of both were investigated in an MCF-7 cell proliferation assay. Further, the samples were screened for changes in gene expression patterns of the MCF-7 cells with Gene Chip arrays. Only at unphysiologically low estrogen levels isoflavones led to minor proliferation-enhancing effects. In contrast, at estradiol levels of >20 pM, isoflavones both tested directly and indirectly (metabolized) revealed significant anti-proliferative effects as well as in the proliferation and the gene chip assay. These findings emphasize the reported advantageous properties of isoflavones for postmenopausal women. PMID:18554862

Imhof, Marianne; Molzer, Sylvia; Imhof, Martin

2008-05-04

33

Ligninase-mediated removal of 17beta-estradiol from water in the presence of natural organic matter: efficiency and pathways.  

PubMed

Lignin peroxidase (LiP) is excreted by certain lignin-degrading fungi, such as white rot fungus Phanerochaete chrysosporium, in natural environments and is thus widely present in the natural environment. We have found in our earlier studies that LiP mediates effective reactions of a few natural and synthetic estrogens to form oligomeric products via radical coupling. We in particular examined the identity and property of the products resulting from 17beta-estradiol (E2) in LiP-mediated oxidative coupling reactions, and the results suggest that such reactions hold great potential in water/wastewater treatment to remove E2 and estrogenicity. Herein, we report a further investigation to postulate possible reaction pathways of E2 with the assistance of ab initio molecular modeling and to more systematically examine the reaction behavior of E2 under sequenced reaction conditions and in systems containing natural organic matter (NOM) at different levels. Our molecular modeling suggested the coupling of E2 likely proceeded via covalent bonding between two E2 radicals at their unsubstituted carbons in phenolic rings. Results obtained from sequenced reagent feed experiments revealed that the coupling products tended to be consumed with increment enzyme treatments, suggesting that most E2 coupling products may still be LiP substrates that can undergo further coupling reactions under catalysis. Higher concentration of NOM present in the reaction system tended to reduce E2 transformation. NOM moieties seemed to couple to each other upon reaction with LiP, which was evidenced by the development of a characteristic absorbance band. PMID:20416920

Mao, Liang; Huang, Qingguo; Luo, Qi; Lu, Junhe; Yang, Xi; Gao, Shixiang

2010-04-22

34

Trolox and 17beta-estradiol protect against amyloid beta-peptide neurotoxicity by a mechanism that involves modulation of the Wnt signaling pathway.  

PubMed

Oxidative stress is a key mechanism in amyloid beta-peptide (A beta)-mediated neurotoxicity; therefore, the protective roles of 17beta-estradiol (E2) and antioxidants (Trolox and vitamin C) were assayed on hippocampal neurons. Our results show the following: 1) E2 and Trolox attenuated the neurotoxicity mediated by A beta and H2O2 as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assays, quantification of apoptotic cells, and morphological studies of the integrity of the neurite network. 2) Vitamin C failed to protect neurons from A beta toxicity. 3) A beta-mediated endoperoxide production, reported to induce cell damage, was decreased in the presence of E2 and Trolox. 4) Two key Wnt signaling components were affected by E2 and Trolox; in fact, the enzyme glycogen synthase kinase 3beta was inhibited by both E2 and Trolox, and both compounds were able to stabilize cytoplasmic beta-catenin. 5) E2 activated the expression of the Wnt-5a and Wnt-7a ligands, and at the same time, E2, through the alpha-estrogen receptor, was able to prevent the excitotoxic A beta-induced rise in bulk-free Ca2+ as an alternative pathway to increase cell viability. 6) Finally, the Wnt-7a ligand protected against cytoplasmic calcium disturbances induced by A beta treatment. Our results suggest that control of oxidative stress, regulation of cytoplasmic calcium, and activation of Wnt signaling may prevent A beta neurotoxicity. PMID:15659394

Quintanilla, Rodrigo A; Muñoz, Francisco J; Metcalfe, Maria J; Hitschfeld, Maureen; Olivares, Gonzalo; Godoy, Juan A; Inestrosa, Nibaldo C

2005-01-19

35

Evaluation of the EDSTAC female pubertal assay in CD rats using 17beta-estradiol, steroid biosynthesis inhibitors, and a thyroid inhibitor.  

PubMed

The Endocrine Disrupter Screening and Testing Advisory Committee has recommended the female pubertal onset assay as a Tier I test to detect potential endocrine-disrupting chemicals (EDs). We evaluated this assay's ability to detect EDs acting through various mechanisms. In two similar experiments, weanling female rats were dosed for 20 days by gavage with vehicle (0.5% methocel) or the following test compounds (mg/kg/day): 17beta-estradiol (E2; 0.1, 2, or 4), ketoconazole (KETO; 24, 50, or 100), finasteride (FIN; 20), testolactone (TL; 220), fadrozole (FAD; 0.6, 1.2, or 6.0) or 6-propylthiouracil (PTU; 240). In vehicle-treated females, mean age at pubertal onset, as evidenced by vaginal opening (VO), varied interexperimentally from 32.3+/-1.6 days to 33.5+/-1.8 days. At 0.1 mg/kg E2, age at VO was reduced slightly to 31.0+/-1.6 days, but not significantly (alpha=0.05). Higher E2 doses (2.0 and 4.0) reduced age at VO to 28 days. KETO delayed VO, but this delay was significant only at 100 mg/kg (39.7+/-2.4 days). FIN and TL had no effect on age at pubertal onset; however, FAD significantly delayed VO. PTU delayed VO to 34.2+/-1.1 days and altered thyroid weight, histology, and hormone levels. With each compound, significant changes in age at VO were accompanied by decreased uterine or ovarian weights. Thus, although this assay did not detect TL or lower doses of E2 (0.1 mg/kg) or KETO (< or = 50 mg/kg), it was capable of detecting EDs operating through a variety of mechanisms. PMID:10630580

Marty, M S; Crissman, J W; Carney, E W

1999-12-01

36

17 beta-estradiol inhibits interleukin-6 production by bone marrow-derived stromal cells and osteoblasts in vitro: a potential mechanism for the antiosteoporotic effect of estrogens.  

PubMed Central

The effect of 17 beta-estradiol on interleukin-6 (IL-6) synthesis was examined in murine bone marrow-derived stromal cell lines, normal human bone-derived cells, and nontransformed osteoblast cell lines from mice and rats. In all these cell types IL-6 production was stimulated as much as 10,000-fold in response to the combination of recombinant interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha). Addition of 17 beta-estradiol in the cultures exerted a dose-dependent inhibition of IL-1-, TNF-, and IL-1 + TNF-induced production of bioassayable IL-6. Testosterone and progesterone (but not 17 alpha-estradiol) also inhibited IL-6, but their effective concentrations were two orders of magnitude higher than 17 beta-estradiol. 17 beta-estradiol also decreased the levels of the IL-6 mRNA. In addition, estradiol inhibited both TNF-induced IL-6 production and osteoclast development in primary bone cell cultures derived from neonatal murine calvaria. The TNF-stimulated osteoclast development was also suppressed by a neutralizing monoclonal anti-IL-6 antibody. This in vitro evidence suggests, for the first time, a mechanistic paradigm by which estrogens might exert at least part of their antiresorptive influence on the skeleton. Images

Girasole, G; Jilka, R L; Passeri, G; Boswell, S; Boder, G; Williams, D C; Manolagas, S C

1992-01-01

37

17BETA-ESTRADIOL DIFFERENTIALLY REGULATES ANDROGEN-RESPONSIVE GENES THROUGH AN ESTROGEN RECEPTOR-BETA-DEPENDENT PATHWAY IN LNCAP HUMAN PROSTATE CANCER CELLS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The molecular mechanism of action of estrogens in normal prostate physiology and prostate cancer development remains unclear. To better understand the molecular effects of estrogen on prostate carcinogenesis, we examined the effect of 17beta-estradiol on the androgen-responsive LNCaP human prostate ...

38

Stimulation of catecholamine synthesis through unique estrogen receptors in the bovine adrenomedullary plasma membrane by 17{beta}-estradiol  

SciTech Connect

Incubation of cultured bovine adrenal medullary cells with 17{beta}-estradiol (E{sub 2}) (0.3-100 nM) or membrane-impermeable E{sub 2}-bovine serum albumin (100 nM) acutely increased {sup 14}C-catecholamine synthesis from [{sup 14}C]tyrosine. The stimulatory effect of E{sub 2} was not inhibited by ICI182,780, a nuclear estrogen receptor inhibitor. E{sub 2} also increased tyrosine hydroxylase activity and p44/42MAPK phosphorylation, the former of which was attenuated by U0126, an inhibitor of p44/42MAPK kinase. The plasma membrane isolated from the gland showed two classes of specific binding sites of [{sup 3}H]E{sub 2} with apparent K {sub d}s of 3.2 and 106 nM, and B {sub max}s of 0.44 and 8.5 pmol/mg protein, respectively. The high-affinity binding of [{sup 3}H]E{sub 2} was most strongly inhibited by E{sub 2} and phytoestrogens, and to lesser extents by other steroid hormones, while it was enhanced by ICI182,780 and environmental estrogenic pollutants. These findings suggest that E{sub 2} acutely stimulates catecholamine synthesis via activation of p44/42MAPK through unique estrogen receptors in the plasma membrane of bovine adrenal medulla.

Yanagihara, Nobuyuki [Department of Pharmacology, University of Occupational and Environmental Health, School of Medicine, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 (Japan)]. E-mail: yanagin@med.uoeh-u.ac.jp; Liu, Minhui [Department of Pharmacology, University of Occupational and Environmental Health, School of Medicine, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 (Japan); Toyohira, Yumiko [Department of Pharmacology, University of Occupational and Environmental Health, School of Medicine, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 (Japan); Tsutsui, Masato [Department of Pharmacology, University of Occupational and Environmental Health, School of Medicine, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 (Japan); Ueno, Susumu [Department of Pharmacology, University of Occupational and Environmental Health, School of Medicine, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 (Japan); Shinohara, Yuko [Department of Pharmacology, University of Occupational and Environmental Health, School of Medicine, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 (Japan); Takahashi, Kojiro [Department of Hospital Pharmacy, University Hospital, University of Occupational and Environmental Health, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 (Japan); Tanaka, Kazumi [Department of Pharmacology, University of Occupational and Environmental Health, School of Medicine, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555 (Japan)

2006-01-13

39

Adsorption of bisphenol-A, 17 beta-estradiole and 17 alpha-ethinylestradiole to sewage sludge.  

PubMed

Adsorption of bisphenol-A (CAS 85-05-7), 17 beta-estradiole (CAS 50-28-2) and 17 alpha-ethinylestradiole (CAS 57-63-6) to activated and to inactivated sludge from wastewater treatment plants (WWTPs) was investigated, thus allowing to distinguish between pure adsorption and biosorption. For the investigated substances the determination of the adsorption kinetics is based on experiments performed according to the OECD guideline 106 and on free concentration measurements in the liquid phase. The description of the adsorption behaviour occurred via Freundlich Adsorption Isotherms. Additionally specific adsorption coefficients KD, KOM and KOC were calculated. The results of these calculations were compared to KOC values obtained with a HPLC method according to the OECD guideline 121. All substances showed a high adsorption affinity to the adsorbent and in spite of the application of very high initial concentrations no saturation level could be reached. Within a contact time of 24 h, no difference between the adsorption to activated and inactivated sludge could be detected. The calculated KD values were within a range of about KD = 1000 l kg(-1) for the investigated compounds and showed a clear concentration dependency in the case of bisphenol-A. Adsorption was also found to depend on pH. The experimentally determined KOC values of the investigated substances were significantly higher than the results obtained with the HPLC method described in OECD guideline 121. PMID:15261530

Clara, Manfred; Strenn, Birgit; Saracevic, Ernis; Kreuzinger, Norbert

2004-09-01

40

The effects of 17beta estradiol, 17alpha estradiol and progesterone on oxidative stress biomarkers in ovariectomized female rat brain subjected to global cerebral ischemia.  

PubMed

Neuroprotective effects of estrogens and progesterone have been widely studied in various experimental models. The present study was designed to compare possible neuroprotective effects of 17alpha-estradiol, 17beta-estradiol, and progesterone on oxidative stress in rats subjected to global cerebral ischemia. Global cerebral ischemia was induced in ovariectomized female rats by four vessel occlusion for 10 min. Following 72 h of reperfusion, levels of malondialdehyde (MDA, oxidative stress marker), and reduced glutathione (GSH, major endogenous antioxidant) were assessed in hippocampus, striatum and cortex of rats treated with either 17alpha-estradiol, 17beta-estradiol, progesterone or estradiol + progesterone beforehand. Steroid administration ameliorated ischemia-induced decrease in GSH and increase in MDA levels. Our data offers additional evidence that estrogens and progesterone or combination of two exert a remarkable neuroprotective effect reducing oxidative stress. PMID:19093730

Ozacmak, V H; Sayan, H

2008-12-17

41

Cosupplementation of isoflavones, prenylflavonoids, and lignans alters human exposure to phytoestrogen-derived 17beta-estradiol equivalents.  

PubMed

The microbial metabolism of dietary phytoestrogens varies considerably among individuals and influences the final exposure to bioactive compounds. In view of the increasing number of food supplements combining several classes of phytoestrogens, the microbial potential to activate various proestrogens within an individual was evaluated in 3 randomized dietary crossovers. Treatment allocation was based on participants' eligibility (>45% in vitro bioactivation of >or=2 separate proestrogens by fecal cultures; n = 40/100). After a run-in of >or=4 d, participants were given soy-, hop-, and/or flax-based food supplements dosed either separately (SOY: 2.83 mg daidzein aglycone equivalents/supplement, HOP: 1.20 mg isoxanthohumol (IX)/supplement, or FLAX: 2.08 mg secoisolariciresinol (SECO) aglycone equivalents/supplement; reference intervention) or simultaneously (MIX; test intervention) 3 times/d for 5 d, followed by a wash-out period (>or=7 d) and the second intervention. Before and after each (co)supplementation, spot urine and serum were collected. In total, 22 equol, 19 8-prenylnaringenin (8-PN), and 21 enterolactone (ENL) producers completed the SOY+MIX, HOP+MIX, and FLAX+MIX trials, respectively. The microbial bioactivation of daidzein, IX, and SECO, generally decreased upon coincubation in vitro (equol: 4.4%, P = 0.164; 8-PN: 20.5%, P < 0.001; ENL: 44.3%, P < 0.001) and cosupplementation in vivo (equol: 28.3%, P = 0.009; 8-PN: 35.4%, P = 0.107; ENL: 35.9%, P = 0.003). Although the bioavailabilities of total isoflavones, prenylflavonoids, and lignans were not significantly affected upon coadministration, participants were exposed to lower phytoestrogen-derived 17beta-estradiol equivalents. In conclusion, the bioavailability of phytoestrogens, especially when given in mixtures, is subject to high interindividual variation. These findings support the importance of personalized screening when assessing the efficacy of such products and mixtures. PMID:19864398

Bolca, Selin; Wyns, Ciska; Possemiers, Sam; Depypere, Herman; De Keukeleire, Denis; Bracke, Marc; Verstraete, Willy; Heyerick, Arne

2009-10-28

42

Maternally derived testosterone and 17beta-estradiol in the eggs of Arctic-breeding glaucous gulls in relation to persistent organic pollutants.  

PubMed

It is largely unknown if and how persistent organic pollutants (POPs) affect the transfer of maternal hormones to eggs. This occurs despite an increasing number of studies relating environmental conditions experienced by female birds at the time of egg formation to maternal hormonal effects. Here we report the concentrations of maternal testosterone, 17beta-estradiol and major classes of POPs (organochlorines, brominated flame retardants and metabolically-derived products) in the yolk of unincubated, third-laid eggs of the glaucous gull (Larus hyperboreus), a top-predator in the Arctic marine environment. Controlled for seasonal and local variation, positive correlations were found between the concentrations of certain POPs and testosterone. Contaminant-related changes in the relative concentrations of testosterone and 17beta-estradiol were also observed. In addition, yolk steroid concentrations were associated with contaminant profiles describing the proportions of different POPs present in the yolk. Eggs from nests in which two sibling eggs hatched or failed to hatch differed in POP profiles and in the relative concentrations of testosterone and 17beta-estradiol. Although the results of this correlative study need to be interpreted with caution, they suggest that contaminant-related changes in yolk steroids may occur, possibly affecting offspring performance over and above toxic effects brought about by POPs in eggs. PMID:18550446

Verboven, Nanette; Verreault, Jonathan; Letcher, Robert J; Gabrielsen, Geir W; Evans, Neil P

2008-05-02

43

Effects of 17 beta-estradiol and medroxyprogesterone acetate upon MtTW15 mammosomatotropic pituitary tumor growth and hormone production in male and female rats.  

PubMed

The purpose of this study was to characterize the effects of two functionally diverse steroids, 17 beta-estradiol and medroxyprogesterone acetate (MPA), on MtTW15 rat mammosomatotropic pituitary tumor growth and hormone production. Steroid responsiveness, as well as the hormonally autonomous nature of the tumor, was studied by treating both male and female tumor-bearing rats for 7 weeks with weekly injections of either 17 beta-estradiol (600 ng/g body weight/week) or MPA (200 microgram/g body weight/week) and, subsequently, comparing both the tumor weights and the in vivo production of growth hormone (GH) and prolactin (PRL) among the treatment groups. Large tumors (6 to 20 gm) were obtained in all treatment groups, indicating hormonal autonomy; however, tumors were markedly smaller, on the average, in untreated males an ovariectomized females. Treatment of such rats with 17 beta-estradiol stimulated tumor growth. Radioimmunoassay of tumor and serum GH and PRL levels in all treatment groups indicated the following: (a) tumors from untreated male or female hosts did not favor the production of one hormone over the other to any great extent; (b) MPA, however, promoted significant increases (p less than 0.05) in GH production in both male and female tumor-bearing rats while having little effect on the production of PRL; and (c) 17 beta-estradiol significantly inhibited (p less than 0.05) GH production and promoted PRL production by tumors borne by either sex. Selected studies utilizing multiple doses of MPA (1 to 500 microgram per gm body weight per week) and 17 beta-estradiol (10 to 800 ng per gm body weight per week) were accomplished and demonstrated that hormone production can be influenced in a dose-related manner. These results indicated that the estrogen-induced MtTW15 rat pituitary tumor is hormonally autonomous, yet divergently responsive to two different classes of steroidal compounds, thus making this tumor line an appropriate model for the study of hormonally responsive pituitary tumor cells. PMID:7214344

Winneker, R C; Parsons, J A

1981-05-01

44

Regulation of beta follicle stimulating hormone subunit RNA by 17-beta estradiol, progesterone, and inhibin in ovine pituitary cells in culture  

SciTech Connect

The molecular mechanism by which ovine follicle stimulating hormone (FSH) is negatively regulated by 17-beta estradiol, progesterone, and inhibin was investigated in vitro, using ovine pituitary cells in culture. The effects of these gonadal hormones on beta FSH RNA levels were assayed by dot blot hybridization to a specific radiolabeled cDNA probe for beta FSH RNA. This was compared to concomitant changes in FSH secretion, which were measured by radioimmunoassay, in order to determine if the alterations in beta FSH RNA could account for the changes in FSH secretion.

Phillips, C.L.

1987-01-01

45

Effects of o,p'-DDE, heptachlor, and 17beta-estradiol on vitellogenin gene expression and the growth hormone/insulin-like growth factor-I axis in the tilapia, Oreochromis mossambicus.  

PubMed

Effects of two endocrine disruptors, o,p'-DDE and heptachlor, and 17beta-estradiol (E(2)) on vitellogenin (Vg) and the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis were examined in male tilapia. In the first experiment, fish were given 5 weekly injections of either E(2), o,p'-DDE or heptachlor (5 microg/g). E(2) treatment increased plasma Vg and hepatic expression of three Vg genes (Vgs A, B, and C) and estrogen receptor alpha (ERalpha), while reducing plasma levels of IGF-I and suppressing the expression of IGF-I, the GH receptor (GHR2) and the putative somatolactin receptor (GHR1). Neither pesticide greatly affected the other parameters examined, except for a significant reduction in expression of GHR2 and increased plasma IGF-I. In the second experiment, fish were given a single injection of o,p'-DDE or heptachlor (100 microg/g), or E(2) (5 microg/g) and sacrificed 5 days post-injection. Treatment with E(2) stimulated expression of all three Vg genes. Both o,p'-DDE and heptachlor increased expression of VgB, whereas only o,p'-DDE increased VgA expression. There was no effect of o,p'-DDE or heptachlor on VgC expression or plasma Vg levels. Treatment with o,p'-DDE and heptachlor as well as E(2) increased ERalpha and ERbeta transcript levels. Similarly, both pesticides increased GHR1 and IGF-I expression, whereas no significant effect of E(2) was observed on GHR1, GHR2 or IGF-I expression. These results indicate that o,p'-DDE and heptachlor have varying temporal and dose effects on modulation of Vg and the GH/IGF-I axis that are distinct from E(2). PMID:19101654

Davis, Lori K; Visitacion, Nancy; Riley, Larry G; Hiramatsu, Naoshi; Sullivan, Craig V; Hirano, Tetsuya; Grau, E Gordon

2008-12-06

46

1alpha,25-dihydroxy-vitamin D3 in combination with 17beta-estradiol lowers the cortical expression of heat shock protein-27 following experimentally induced focal cortical ischemia in rats.  

PubMed

1alpha,25-(OH)(2)-vitamin-D(3) (1,25-D(3)) and 17beta-estradiol are both known to act neuroprotective in certain experimental in vitro and in vivo settings. We studied the effects of 1,25-D(3) or 17beta-estradiol or their combined application on heat shock protein-27 (HSP-27) distribution after focal cortical ischemia using the photothrombosis model. HSP-27 is a well-established marker of the cerebral oxidative stress response and a potent inhibitor of apoptosis. Lesioned rats were injected i.p. one hour after injury with either 1 microg 1,25-D(3)/kg or 7 microg 17beta-estradiol/kg or a combination of both steroids. Groups of non-lesioned steroid-treated rats and lesioned, solvent-treated rats served as controls. Treatment with both steroids did not affect the size of the lesion. In addition, 17beta-estradiol resulted in significant reduction of HSP-27 induction, whereas the combination of 1,25-D(3)+17beta-estradiol resulted in a highly significant reduction of HSP-27 within the infracted cerebral cortex, indicating that both steroids act synergistically in a protective manner. PMID:15922286

Losem-Heinrichs, Eva; Görg, Boris; Redecker, Christoph; Schleicher, Axel; Witte, Otto W; Zilles, Karl; Bidmon, Hans-J

2005-07-01

47

Modulation of peroxisome proliferator-activated receptors (PPARs) by PPAR(alpha)- and PPAR(gamma)-specific ligands and by 17beta-estradiol in isolated zebrafish hepatocytes.  

PubMed

Peroxisome proliferation is a phenomenon occurring when responsive animals are exposed to certain compounds so-called peroxisome proliferators and is regulated through a nuclear receptor named peroxisome proliferator-activated receptor (PPAR). PPAR family members exhibit a strong binding affinity for both saturated and unsaturated fatty acids. Activators of PPAR(alpha) include a variety of endogenously present fatty acids, leukotrienes and hydroxyeicosatetraenoic acids (HETEs) and clinically used drugs, such as fibrates. PPAR(beta) activators include fatty acids, prostaglandin A2 (PGA2) and prostacyclin (PGI2). PPAR(gamma) is the most selective receptor and, among others, 15-deoxy-Delta(12,14) prostaglandin J2 (PGJ2) has been described to be a PPAR(gamma)-specific ligand. The aim of the present study was to determine if known PPAR(alpha) and PPAR(gamma) ligands were able to alter the expression of these subtypes in an in vitro model of zebrafish primary hepatocyte culture. With this purpose, a PPAR(alpha) specific ligand (8S-HETE), a PPARgamma specific ligand (PGJ) and a peroxisome proliferator of the fibrate class (clofibrate) were selected. In addition, the female hormone 17beta-estradiol was also used as it is known to interact with PPARs. After cell exposure for 24 h, cells were immunohistochemically stained for both PPARs and immunolabeling was quantified as percentage of positive nuclei and cells. Levels of expression of PPARs were also measured by image analysis as grey level per cell. Expression was induced for both PPAR(alpha) and PPAR(gamma) by clofibrate (at 0.5 mM for PPAR(alpha) and at 1 and 2 mM for PPAR(gamma)), by HETE (1 microM), and by PGJ2 (0.3 and 1 microM for PPAR(alpha) and 0.3 microM for PPAR(gamma)). Expression of PPARgamma was also induced at 10 microM by 17beta-estradiol. The percentage of PPAR(alpha) positive nuclei increased significantly at 1 microM HETE and the percentage of PPAR(gamma) positive cells decreased at 10 microM 17beta-estradiol. As a conclusion, clofibrate, HETE and PGJ2 are able to induce expression of both PPAR(alpha) and PPAR(gamma) in zebrafish primary hepatocyte cultures. Further studies are needed to identify how the expression of different PPAR subtypes is regulated and to elucidate the implication of PPAR subtypes in zebrafish cell functions. PMID:15964169

Ibabe, A; Herrero, A; Cajaraville, M P

2005-09-01

48

Local and humoral immune responses against primary and repeat Neisseria gonorrhoeae genital tract infections of 17beta-estradiol-treated mice.  

PubMed

The 17beta-estradiol-treated mouse model is the only small animal model of gonococcal genital tract infection. Here we show gonococci localized within vaginal and cervical tissue, including the lamina propria, and high numbers of neutrophils and macrophages in genital tissue from infected mice. Infection did not induce a substantial or sustained increase in total or gonococcal-specific antibodies. Mice could be reinfected with the same strain and repeat infection did not boost the antibody response. However, intravaginal immunization of estradiol-treated mice induced gonococcal-specific primary and secondary serum antibody responses. We conclude that similar to human infection, experimental murine infection induces local inflammation but not an acquired immune response or immunological memory. PMID:18762223

Song, Wenxia; Condron, Sara; Mocca, Brian T; Veit, Sandra J; Hill, Dawn; Abbas, Asima; Jerse, Ann E

2008-08-30

49

Selection of reliable reference genes for qRT-PCR studies on cetacean fibroblast cultures exposed to OCs, PBDEs, and 17beta-estradiol.  

PubMed

Quantitative real-time PCR (qRT-PCR) represents an effective molecular technique for the detection of mRNA expression in biological samples. Its sensitivity allows the quantification of slight changes in the regulation of gene transcription but is strictly dependent upon the method followed during the normalization procedure. Relative quantification determines changes in the steady-state mRNA levels of genes across multiple samples and it is assessed by comparison with the levels of one or more internal control RNA. In this context, the choice of constitutively expressed control genes, whose transcription is not affected by the contaminants, appears to be fundamental for the reliability of this technique. During this study, fibroblast cell cultures originated from integumentum biopsies, sampled in the cetacean species Stenella coeruleoalba, have been exposed for 6h to increasing concentrations of different mixtures of compounds with endocrine disruptor capacities (EDCs): organochlorines (OCs), polybrominated diphenyl ethers (PBDEs), and 17beta-estradiol. Ten common housekeeping genes have been tested for the expression of their transcripts in exposed cell cultures using qRT-PCR assays and raw data were analyzed with the two Excel applets geNorm and NormFinder. The genes encoding for SDHA, GAPDH and YWHAZ appear to be the most reliable controls, respectively, for the OC, PBDE and 17beta-estradiol treatments. These results clearly show that the transcription of even widely diffused control genes can be regulated by different treatments and underlie the importance of a careful selection of the optimal housekeeping genes in toxicological studies. PMID:18339435

Spinsanti, Giacomo; Panti, Cristina; Bucalossi, Daniela; Marsili, Letizia; Casini, Silvia; Frati, Francesco; Fossi, Maria Cristina

2008-02-08

50

Regulation of estrogen receptor beta mRNA in the brain: opposite effects of 17beta-estradiol and the phytoestrogen, coumestrol.  

PubMed

Estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta) are differentially distributed in the brain and likely mediate different estrogen-dependent processes. ERbeta is abundant in the bed nucleus of the stria terminalis, medial preoptic nucleus, paraventricular nucleus of the hypothalamus and the amygdala of the rat. In the paraventricular nucleus, which is devoid of ERalpha, ERbeta is colocalized with the neuropeptides, oxytocin and vasopressin, suggesting a potential functional role for ERbeta in the regulation of these peptides. We examined the regulation of ERbeta mRNA expression in the rat brain by 17beta-estradiol and the phytoestrogen, coumestrol. 17beta-Estradiol treatment decreased ERbeta mRNA in situ hybridization signal by 44.5% in the paraventricular nucleus of the hypothalamus (PVN), but had no effect in the bed nucleus of the stria terminalis (BnST) or the medial preoptic nucleus (MPA). In contrast, dietary exposure to coumestrol increased ERbeta mRNA signal by 47.5% in the PVN but had no effect in the BnST or the MPA. These data demonstrate that like ERalpha, ERbeta is down regulated by estrogen in a region specific manner in the rat brain. Furthermore, exposure to coumestrol may modulate ERbeta-dependent processes by acting as an anti-estrogen at ERbeta. This data contradicts results from cell transfection assays which suggest an estrogenic activity of coumestrol on ERbeta, indicating that the mode of action may be tissue specific, or that metabolism of dietary coumestrol may alter its effects. Because the highest concentrations of phytoestrogens are found in legumes, vegetables and grains, they are most prevalent in vegetarian and traditional Asian diets. Understanding the neuroendocrine effects of phytoestrogens is particularly important now that they are being marketed as a natural alternative to estrogen replacement therapy and sold in highly concentrated pills and powders. PMID:10101243

Patisaul, H B; Whitten, P L; Young, L J

1999-04-01

51

17 beta-estradiol attenuates pressure overload-induced myocardial hypertrophy through regulating caveolin-3 protein in ovariectomized female rats.  

PubMed

Our findings indicate that in ovariectomized female rats abdominal aortic constriction led to significant increases in left ventricular mass, myocyte diameter and heart weight/body weight (HW/BW) value, and decreases in interventricular septal thickness at diastole (IVSd), left ventricular percent fractional shortening (FS) and ejection fraction (EF). These pathophysiological alterations were largely reversed by administration with 17?-estradiol for eight weeks. Furthermore, the enhanced expression of extracellular signal-regulated kinases 1/2 and decreased expression of caveolin-3 were found in left ventricle of AAC group. 17?-estradiol (E(2)) administration increased the expression of caveolin-3 and reduced the level of ERK phosphorylation in these pressure-overloaded rats. Moreover, in cultured neonatal rat cardiomyocytes, E(2) inhibited the hypertrophic response to angiotensin II. This effect was reinforced by the addition of extracellular signal-regulated kinases 1/2 inhibitor PD98059, but was impaired when the cells were pretreated with caveolae disruptor, methyl-?-cyclodextrin (M-?-CD). In conclusion, our data indicate that estrogen attenuates the hypertrophic response induced by pressure overload through down-regulation of extracellular signal-regulated kinases 1/2 phosphorylation and up-regulation of caveolin-3 expression. PMID:21170593

Cui, Yu-Hong; Tan, Zhi; Fu, Xiao-Dong; Xiang, Qiu-Ling; Xu, Jin-Wen; Wang, Ting-Huai

2010-12-18

52

Differential effects of 17beta-estradiol on function and expression of estrogen receptor alpha, estrogen receptor beta, and GPR30 in arteries and veins of patients with atherosclerosis  

Microsoft Academic Search

Venous complications have been implicated in the adverse effects of hormone replacement therapy. This study investigated acute effects of the natural estrogen, 17beta-estradiol, on function, estrogen receptors\\/GPR30 expression, and kinase activation in vascular rings and cultured smooth muscle cells from arteries and veins of patients with coronary artery disease. Changes in vascular tone of internal mammary arteries and saphenous veins

E. Haas; M. R. Meyer; U. Schurr; I. Bhattacharya; R. Minotti; H. H. Nguyen; A. Heigl; M. Lachat; M. Genoni; M. Barton

2007-01-01

53

Rainfall and tillage effects on transport of fecal bacteria and sex hormones 17beta-estradiol and testosterone from broiler litter applications to a Georgia Piedmont Ultisol.  

PubMed

Poultry litter provides nutrients for crop and pasture production; however, it also contains fecal bacteria, sex hormones (17beta-estradiol and testosterone) and antibiotic residues that may contaminate surface waters. Our objective was to quantify transport of fecal bacteria, estradiol, testosterone and antibiotic residues from a Cecil sandy loam managed since 1991 under no-till (NT) and conventional tillage (CT) to which either poultry litter (PL) or conventional fertilizer (CF) was applied based on the nitrogen needs of corn (Zea mays L) in the Southern Piedmont of NE Georgia. Simulated rainfall was applied for 60 min to 2 by 3-m field plots at a constant rate in 2004 and variable rate in 2005. Runoff was continuously measured and subsamples taken for determining flow-weighted concentrations of fecal bacteria, hormones, and antibiotic residues. Neither Salmonella, nor Campylobacter, nor antimicrobial residues were detected in litter, soil, or runoff. Differences in soil concentrations of fecal bacteria before and after rainfall simulations were observed only for Escherichia coli in the constant rainfall intensity experiment. Differences in flow-weighted concentrations were observed only for testosterone in both constant and variable intensity rainfall experiments, and were greatest for treatments that received poultry litter. Total loads of E. coli and fecal enterococci, were largest for both tillage treatments receiving poultry litter for the variable rainfall intensity. Load of testosterone was greatest for no-till plots receiving poultry litter under variable rainfall intensity. Poultry litter application rates commensurate for corn appeared to enhance only soil concentrations of E. coli, and runoff concentrations of testosterone above background levels. PMID:18571694

Jenkins, Michael B; Truman, Clint C; Siragusa, Gregory; Line, Eric; Bailey, J Stan; Frye, Jonathan; Endale, Dinku M; Franklin, Dorcas H; Schomberg, Harry H; Fisher, Dwight S; Sharpe, Ronald R

2008-06-20

54

Mitogenic estrogen metabolites alter the expression of 17beta-estradiol-regulated proteins including heat shock proteins in human MCF-7 breast cancer cells.  

PubMed

Estrogen metabolites are carcinogenic. The comparative mitogenic activities of 17b-estradiol (E2) and four metabolites, 2-hydroxyestradiol (2-OHE2), 4-hydroxyestradiol (4-OHE2), 16a-hydroxyestrone (16a-OHE1) and 2-methoxyestradiol (2-ME), were determined in estrogen receptor(ER)-positive MCF-7 human breast cancer cells. Each of the E2 metabolites caused proliferation of the MCF-7 cells, but only E2 and 16a-OHE1 induced a greater than 20-fold increases in transcripts of the progesterone receptor (PR) gene, a classical ER-mediated gene. This suggests that the mitogenic action of E2 and 16a-OHE1 could result from their effects on gene expression via the ER. E2 metabolites altered the expression of E2-regulated proteins including heat shock proteins (Hsps). 16a-OHE1 and 2-ME as well as E2 increased levels of Hsp56, Hsp60, Hsp90a and Hsp110 transcripts, and the patterns of these inductions resembled that of PR. Hsp56 and Hsp60 protein levels were increased by all the E2 metabolites. Levels of the transcripts of 3 E2-upregulated proteins (XTP3-transactivated protein A, protein disulfide isomerase-associated 4 protein and stathmin 1) and an E2-downregulated protein (aminoacylase 1) were also affected by the E2 metabolites. These results suggest that the altered expression of Hsps (especially Hsp56 and Hsp60) by E2 metabolites such as E2, 16a-OHE1 and 2-ME could be closely linked to their mitogenic action. PMID:16404153

Kim, Seong Hwan; Lee, Su-Ui; Kim, Myung Hee; Kim, Bum Tae; Min, Yong Ki

2005-12-31

55

HCG, Progesterone and 17-Beta-Estradiol Levels during Extra-Amniotically Induced Early Abortion by a New Prostaglandin Derivative (Sulprostone)  

Microsoft Academic Search

A new prostaglandin E2 derivative (Sulprostone) was given extra-amniotically to 17 healthy women, who were 7–8 weeks pregnant, in order to assess the plasma profile of HCG, 17?-estradiol (E2), and progesterone and to evaluate the effectiveness and overall acceptability of the method in relation to different dose levels. On the lowest dose level (5 ?g) only 3 of 7 patients

Staffan Nilsson; Göran Zador; Karl-Gösta Nygren; Leif Wide

1981-01-01

56

Biodistribution and metabolism of 16. cap alpha. -((/sup 18/F)-fluoro)-17. beta. -estradiol  

SciTech Connect

The uptake of receptor-mediated radiopharmaceuticals as measured by target to non-target uptake ratios depends upon many parameters. These include blood flow to the tissue, blood volume, receptor concentration as well as metabolism of the tracer. In a rat tumor model (DMBA) induced mammary tumors with high concentration of estrogen receptors) uptake of /sup 18/F-estradiol was studied while blood flow was measured with the use of /sup 125/I-iodoantipyrine, blood volume was measured with the use of /sup 99m/Tc-labeled red blood cells, and the receptor concentration by in vitro assay. The results demonstrate no correlation between blood flow and uptake of ligand, or between receptor concentration and uptake of ligand. No correlation existed between blood volume and uptake or /sup 18/F-estradiol, even though the blood volume varied by a factor of --20 in the tumors studied. The distribution of the fluorine-18 may depend upon metabolites of the ligand rather than the ligand itself. The authors have developed a technique to separate metabolites from the administered compound in blood and tissues. The distribution of the compound in the blood at times >30 mins after injection was primarily within the red blood cells in a chemical form that was not extractable even in lysed blood samples. By injecting blood from one rate into another the authors have shown that the activity in blood 2 hours after injection of /sup 18/F-estradiol is not available for uptake in receptor rich tissue but remains in the blood and non-target tissues.

Mathias, C.J.; Brodack, J.W.; Kilbourn, M.R.; Carlson, K.A.; Katzenellenbogen, J.A.; Welch, M.J.

1985-05-01

57

Studies on the Novel Anticancer Agents Metabolically Formed form 17- Beta-Estradiol.  

National Technical Information Service (NTIS)

This is the final report for my Predoctoral Traineeship Award (No. DAMD17-02-1-0566). The studies described in the original grant proposal have been completed. Our major findings included the following: (1) We demonstrated, for the first time, that a nove...

A. J. Lee

2004-01-01

58

Lipocalin 2: a "sexy" adipokine that regulates 17Beta-estradiol and obesity  

Technology Transfer Automated Retrieval System (TEKTRAN)

In this article we review the findings of Guo et. al. (Endocrinology, 153: 1183-1193) that the protein, Lipocalin 2 is more highly expressed in subcutaneous adipose tissue than in gondal tissue of female mice. Of particular interest is that the paper by Guo et. al. observed that ablation of the Lip...

59

Adrenocortical response to 17-Beta estradiol replacement in oophorectomized female sprague dawley rats.  

PubMed

Objective: To determine the effect of estradiol treatment on serum corticosterone levels in Oophorectomized (OVX) female Sprague Dawley rats exposed to chronic restraint stress. Study Design: Experimental study. Place and Duration of Study: Department of Physiology, Army Medical College, Rawalpindi and National Institute of Health, Islamabad, from January to December 2008. Methodology: A total of 90 female Sprague Dawley rats (age: 90 ± 10 days), were divided into three groups, each having 30 rats. Group-I comprised of healthy control female rats whereas group-II and III were experimental female rats exposed to chronic restraint stress after bilateral Oophorectomy and called estradiol treated and vehicle treated groups. Estradiol treatment of Oophorectomized rats was done once daily for 2 weeks. At the end of experiment, the rats were sacrificed and intracardiac blood sampling was done to measure serum corticosterone levels by enzyme linked immunosorbent assay (ELISA) kit. Results: The restraint stress to estradiol treated rats for 2 weeks revealed that serum corticosterone levels were significantly increased (31.32 ± 5.46 ng/ml, p < 0.05) as compared to the healthy controls (17.48 ± 4.14 ng/ml). Conclusion: Chronic restraint stress results increases the serum corticosterone levels in Oophorectomized Sprague Dawley rats. Estradiol treatment increases the responsiveness of adrenal cortex of Oophorectomized female rats. PMID:24112252

Farid, Sadaf; Hussain, Muhammad Mazhar; Asad, Munazza

2013-10-01

60

The effect of 17 beta-estradiol on cholesterol in human macrophages is influenced by the lipoprotein milieu  

Technology Transfer Automated Retrieval System (TEKTRAN)

Estrogen and testosterone are thought to modulate coronary heart disease (CHD) risk. To examine how these hormones affect human macrophage cholesterol transport, a key factor in atherogenesis, we obtained monocytes from healthy male and postmenopausal female donors (age 50-70 y). Cells were allowe...

61

PROMOTION BY 17BETA-ESTRADIOL AND BETA-HEXACHLOROCYCLOHEXANE OF HEPATOCELLULAR TUMORS IN MEDAKA, ORYZIAS LATIPES. (R825298)  

EPA Science Inventory

Abstract A feature common to many laboratory and field studies with various fish species is a higher prevalence of hepatocellular neoplasia in females than in males. During female sexual maturation, endogenous estrogens stimulate substantial increases in synthetic acti...

62

The effect of 17beta estradiol withdrawal on the level of brain and peripheral neurosteroids in ovarectomized rats.  

PubMed

Dehydroepiandrosterone (DHEA), pregnenolone (P) and their sulfate derivatives are neuroactive neurosteroids synthesized endogenously in the brain and in steroidogenic organs and influence or are influenced by a variety of physiological processes. Since parturition is followed by a rapid drop in estrogen levels in serum and brain it may be hypothesized that the drastic drop in the brain exposure to estrogens may cause a disturbance in the neurosteroid-to-neurosteroid-sulfate equilibrium with clinical relevance. In order to develop a rat animal model for human postpartum rapid estrogen decline conditions, the present study investigated effects of sudden withdrawal of hyperphysiological estrogens levels on levels of DHEA, DHEAS, P and PS in peripheral blood and brain tissue as well as cortical sulfatase activity. Twenty-four 3-month-old female rats were ovarectomized followed by either no estrogen, high levels of estrogen alone, or followed by sudden withdrawal after high-administered estrogen levels. Results indicated elevated brain cortical DHEA-S and reduced cortical sulfatase in ovarectomized rats following sudden estrogen withdrawal. No significant alterations in DHEA, P or PS were noted. Study observations suggest the marked influence estrogen withdrawal states may have on cortical DHEA-S levels in particular, the precise mechanism of which remains unknown but which may be related to the paralleled decrease in sulfatase activity. This DHEA-S increase may lead to attenuated GABAergic tone and may be relevant to post-natal behavioral disturbances (e.g. depression, anxiety). PMID:15927368

Maayan, Rachel; Strous, Rael D; Abou-Kaoud, Machmoud; Weizman, Abraham

63

Engineering the steroid-specificity of an anti-17beta-estradiol Fab by random mutagenesis and competitive phage panning  

Microsoft Academic Search

containing on average 2-4 amino acid changes. We selected for decreased testosterone (TES) cross-reactivity by adding a large excess TES as a competitor to the panning reactions. After four panning rounds, the cross-reactivities of the individual mutant clones ranged from 19 to 4%, showing up to 20-fold improvement over the original value (78%). Estradiol affinities were mainly unchanged. Sequencing of

Petri Saviranta; Maria Pajunen; Piitu Jauria; Matti Karp; Kim Pettersson; Pekka Mantsala; Timo Lovgren

1998-01-01

64

Estrogen receptor-related receptor alpha mediates up-regulation of aromatase expression by prostaglandin E2 in prostate stromal cells.  

PubMed

Estrogen receptor-related receptor alpha (ERRalpha) is an orphan member of the nuclear receptor superfamily of transcription factors. ERRalpha is highly expressed in the prostate, especially in prostate stromal cells. However, little is known about the regulation and function of ERRalpha, which may contribute to the progression of prostatic diseases. We previously found that prostaglandin E2 (PGE2) up-regulated the expression of aromatase in prostate stromal cells. Here we show that PGE2 also up-regulates the expression of ERRalpha, which, as a transcription factor, further mediates the regulatory effects of PGE2 on the expression of aromatase. ERRalpha expression was up-regulated by PGE2 in prostate stromal cell line WPMY-1, which was mediated mainly through the protein kinase A signaling pathway by PGE2 receptor EP2. Suppression of ERRalpha activity by chlordane (an antagonist of ERRalpha) or small interfering RNA knockdown of ERRalpha blocked the increase of expression and promoter activity of aromatase induced by PGE2. Overexpression of ERRalpha significantly increased aromatase expression and promoter activity, which were further augmented by PGE2. Chromatin immunoprecipitation assay demonstrated that ERRalpha directly bound to the aromatase promoter in vivo, and PGE2 enhanced the recruitment of ERRalpha and promoted transcriptional regulatory effects on aromatase expression in WPMY-1. 17Beta-estradiol concentration in WPMY-1 medium was up-regulated by ERRalpha expression, and that was further increased by PGE2. Our results provided evidence that ERRalpha contributed to local estrogen production by up-regulating aromatase expression in response to PGE2 and provided further insights into the potential role of ERRalpha in estrogen-related prostatic diseases. PMID:20351196

Miao, Lin; Shi, Jiandang; Wang, Chun-Yu; Zhu, Yan; Du, Xiaoling; Jiao, Hongli; Mo, Zengnan; Klocker, Helmut; Lee, Chung; Zhang, Ju

2010-03-29

65

DNA ARRAYS TO MONITOR GENE EXPRESSION IN RAT BLOOD AND UTERUS FOLLOWING 17BETA-ESTRADIOL EXPOSURE: BIOMONITORING ENVIRONMENTAL EFFECTS USING SURROGATE TISSUES  

EPA Science Inventory

We propose that gene expression changes in accessible tissues such as blood often reflect those in inaccessible tissues, thus offering a convenient biomonitoring method to provide insight into the effects of environmental toxicants on such tissues. In this pilot study, gene expre...

66

Modulation of vitellogenin synthesis through estrogen receptor beta-1 in goldfish (Carassius auratus) juveniles exposed to 17-{beta} estradiol and nonylphenol  

SciTech Connect

Many synthetic chemicals, termed xenoestrogens, have been shown to interact as agonists with the estrogen receptor (ER) to elicit biological responses similar to those of natural hormones. To date, the regulation of vitellogenesis in oviparous vertebrates has been widely used for evaluation of estrogenic effects. Therefore, Carassius auratus juveniles were chosen as a fish model for studying the effects of estradiol-17{beta} and different concentrations (10{sup -6} and 10{sup -7} M) of 4-nonylphenol (4-NP) on the expression of liver ER{beta}-1 subtype; plasma vitellogenin and sex steroids (androgens and estradiol-17{beta}) were also evaluated together with the bioaccumulation process, through mass-spectrometry. C. auratus is a species widespread in the aquatic environment and, on the toxicological point of view, can be considered a good 'sentinel' species. Juveniles of goldfish were maintained in tanks with only tap water or water with different concentrations (10{sup -6} and 10{sup -7} M) of 4-nonylphenol (4-NP), or 10{sup -7} M of estradiol-17{beta}. After 3 weeks of treatment, animals were anesthetized within 5 min after capture, and blood was immediately collected into heparinized syringes by cardiac puncture and stored at -70 deg. C; the gonads were fixed, then frozen and stored at -70 deg. C; the whole fish, liver, and muscle tissues were harvested and immediately stored at -70 deg. C for molecular biology experiments and bioaccumulation measurements. The estrogenic effects of 4-NP were evidenced by the presence of plasma vitellogenin in juveniles exposed both to estradiol-17{beta} and the two doses of 4-NP; moreover, exposure to 4-NP also increased aromatization of androgens, as suggested by decreasing androgens and increasing estradiol-17{beta} plasma levels. The changes of these parameters were in agreement with the increasing transcriptional rate of ER{beta}-1 mRNA in the liver, demonstrating that both estradiol-17{beta} and 4-NP modulate the vitellogenin rate through interaction with the ER{beta}-1 subtype. The present study also suggests that 4-NP at the concentration of 10{sup -6} M bioaccumulates in the liver.

Soverchia, L. [Dipartimento di Medicina Sperimentale e Sanita Pubblica, Universita degli Studi di Camerino, via Scalzino 3, 62032 Camerino (Monaco) (Italy); Ruggeri, B. [Dipartimento di Scienze Morfologiche e Biochimiche Comparate, Universita degli Studi di Camerino, via Camerini 2, 62032 Camerino (Monaco) (Italy); Palermo, F. [Dipartimento di Scienze Morfologiche e Biochimiche Comparate, Universita degli Studi di Camerino, via Camerini 2, 62032 Camerino (Monaco) (Italy); Mosconi, G. [Dipartimento di Scienze Morfologiche e Biochimiche Comparate, Universita degli Studi di Camerino, via Camerini 2, 62032 Camerino (Monaco) (Italy); Cardinaletti, G. [Dipartimento di Scienze Morfologiche e Biochimiche Comparate, Universita degli Studi di Camerino, via Camerini 2, 62032 Camerino (Monaco) (Italy); Scortichini, G. [Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise 'G. Caporale', Campo Boario, 64100 Teramo (Italy); Gatti, G. [Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise 'G. Caporale', Campo Boario, 64100 Teramo (Italy); Polzonetti-Magni, A.M. [Dipartimento di Scienze Morfologiche e Biochimiche Comparate, Universita degli Studi di Camerino, via Camerini 2, 62032 Camerino (Monaco) (Italy)]. E-mail: alberta.polzonetti@unicam.it

2005-12-15

67

Uterine physiological responses and global gene expression in ovariectomized (ovx) rats treated with soy protein isolate (spi) or 17Beta-estradiol  

Technology Transfer Automated Retrieval System (TEKTRAN)

Concerns regarding increased endometrial cancer risk have been raised in women who consume soy products as the result of the estrogenicity of phytochemical components such as the isoflavones genistein and daidzein. Female Sprague-Dawley rats (N = 20/group) were fed AIN-93G diets with casein or SPI a...

68

Hepatic gene expression following consumption of soy protein isolate in female sprague-dawley rats differs from that produced by 17beta-estradiol treatment  

Technology Transfer Automated Retrieval System (TEKTRAN)

Although soy foods have been recognized as an excellent source of protein, there have been recent concerns regarding potential adverse effects of isoflavone phytochemicals found in soy products, which are known to bind and activate estrogen receptors. Here we used global hepatic gene expression prof...

69

Mammary gland morphology and gene expression differ in female rats treated with 17 beta-estradiol or fed soy protein isolate  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soy foods have been suggested to have both positive health benefits and potentially adverse effects as a result of their content of phytoestrogens. However, studies on the estrogenicity of soy foods are lacking. Here we directly compared the effects of soy protein isolate (SPI), the protein in soy i...

70

PROMOTION BY 17&BETA;-ESTRADIOL AND &BETA;-HEXACHLOROCYCLOHEXANE OF HEPATOCELLULAR TUMORS IN MEDAKA, ORYZIAS LATIPES. AQUAT. (R828676C002)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

71

Effects of FSH and 17beta-estradiol on the transactivation of estrogen-regulated promoters and cell proliferation in L cells.  

PubMed

In the present study, we analyzed human follicle-stimulating hormone (FSH)-induced cell proliferation and transactivation of estrogen-sensitive reporter genes-in L cells stably expressing the human FSH receptor [L-(hFSHR(+)) cells]. In order to dissect the signaling pathways involved in this process, L-(hFSHR(+)) cells were transiently transfected with either the 3X-ERE-TAT-Luc or the ERE-VitA2-TK-CAT reporter genes and treated with FSH or PKA activators (cholera toxin, forskolin and 8-Br-cAMP) in the presence or absence of various kinase inhibitors. We found that FSH and all PKA activators, specifically induced transactivation of both reporter genes. Transactivation of estrogen-sensitive genes by FSH or PKA activators were blocked (approximately 90%) by H89 (PKA inhibitor) and LY294002 but not by Wortmannin (PI3-K inhibitors), 4-OH-tamoxifen, ICI182,780 or SB203580 (p38 MAPK inhibitor); PD98059 (ERK1/2 inhibitor) partially (approximately 30%) blocked the FSH-mediated effect. The combination of FSH and estradiol resulted in a synergistic effect on transactivation as well as on cell proliferation, and this enhancement was attenuated by antiestrogens. We additionally analyzed the participation of the coactivators SRC-1 and cAMP response element binding protein (CREB)-binding protein (CBP) in FSH-evoked estrogen receptor (ER)-dependent transactivation; we found that CBP but not SRC-1 potentiated FSH-induced transcriptional activation of both ER-sensitive reporters, being this effect stronger on the ERE-VitA2-TK-CAT than on the 3X-ERE-TAT-Luc reporter. Thus, in L-(hFSHR(+)) cells FSH induces transcriptional activation of estrogen-sensitive genes through an A-kinase-triggered signaling pathway, using also to a lesser extent the ERK1/2 and p38 pathways. PI3-K is not apparently involved in this FSH-mediated process since LY294002, but not Wortmannin, specifically binds ERs and completely blocks estrogen action. Presumably, CBP cooperates with the ER on genes that contain estrogen responsive elements through mechanisms involving the participation of other proteins and/or basal transcription factors (e.g. CREB), which in turn mediate the transcriptional response of estrogen-sensitive reporter genes to FSH stimulation. PMID:15857748

Pasapera, Ana María; Jiménez-Aguilera, María del Pilar; Chauchereau, Anne; Milgrom, Edwin; Olivares, Aleida; Uribe, Aída; Gutiérrez-Sagal, Rubén; Ulloa-Aguirre, Alfredo

2005-02-12

72

Pathogenic infection confounds induction of the estrogenic biomarker vitellogenin in rainbow trout  

Technology Transfer Automated Retrieval System (TEKTRAN)

To examine the behavior of the estrogenic biomarker vitellogenin (VTG) under the combined impact of estrogens and pathogens, parasite-infected or noninfected rainbow trout were exposed to two doses of 17 beta-estradiol (E2). Infected and E2-exposed fish showed significantly lower hepatic VTG mRNA le...

73

Protective effects of 17beta-estradiol on post-ischemic cardiac dysfunction and norepinephrine overflow through the non-genomic estrogen receptor/nitric oxide-mediated pathway in the rat heart.  

PubMed

The present study was undertaken to examine the effect of acute treatment with 17?-estradiol on post-ischemic cardiac dysfunction and norepinephrine overflow and its possible mechanisms. Male rat hearts were perfused with the Langendorff method and subjected to 40 min of global ischemia followed by 30 min of reperfusion. Each drug was perfused from 15 min before ischemia to 5 min after reperfusion. During reperfusion, 17?-estradiol treatment showed significantly greater functional recovery of left ventricular developed pressure (LVDP), left ventricular end diastolic pressure (LVEDP), and dP/dt(max). Excessive norepinephrine release in coronary effluent from the post-ischemic heart was notably suppressed by treatment with 17?-estradiol. These beneficial effects of 17?-estradiol were not observed in the presence of the nitric oxide synthase inhibitor N(G)-nitro-l-arginine and estrogen receptor antagonist ICI 182,780 ((7?, 17?)-7-[9-[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol), respectively. When NO(2)/NO(3) levels in coronary effluents after the onset of reperfusion were measured, reverse-correlation relationships between NO(2)/NO(3) production and ischemia/reperfusion-induced cardiac dysfunction, as well as norepinephrine overflow were observed. These findings suggest that 17?-estradiol exerts cardioprotective effects against ischemia/reperfusion-induced cardiac dysfunction, at least in part, by suppressing norepinephrine overflow, and that nitric oxide production via estrogen receptor activation plays a key role in this process. PMID:23219795

Fukumoto, Taiki; Tawa, Masashi; Yamashita, Naoto; Ohkita, Mamoru; Matsumura, Yasuo

2012-12-05

74

Estradiol esters can replace 17 beta-estradiol in the stimulation of DNA and esterase synthesis by MCF-7 cells: a possible role for the estrogen-sensitive MCF-7 cell esterase.  

PubMed

In this communication we extend our earlier observations on estrogen-sensitive carboxyl esterases in MCF-7 human breast cancer cells able to hydrolyze esters of estradiol. Using either estradiol acetate or p-nitrophenyl hexanoate as substrates, esterase activity was found to increase 2-3-fold in MCF-7 cells maintained in the presence of 10(-8) M estradiol. Following sucrose density centrifugation, over 85% of total esterase activity was found in the cytoplasmic fraction. No esterase activity was found in spent media from growing cells. By size exclusion chromatography, estradiol acetate esterase activity exhibited a mol. wt of 45-50 kDa. Attempts to demonstrate incorporation of [3H]estradiol into estradiol fatty acid esters by the above MCF-7 cell line (203P) were unsuccessful, although, such incorporation could be demonstrated in two other MCF-7 cell sublines. Incubation of the 203P cells with 10 nM [3H]estradiol in the presence of 0.5 mM radioinert estradiol acetate resulted in the incorporation of 35 +/- 12% of the label into the estradiol acetate in 10 min. In the absence of radioinert estradiol acetate, no incorporation was observed. When MCF-7 cells were incubated with [3H]estradiol in the presence of a large excess of radioinert estradiol valerate, label was found only in estradiol valerate. Similarly, when the incubation was carried out in the presence of a mixture of radioinert estradiol acetate and valerate, label was incorporated into both esters. We conclude that the apparent formation of radiolabeled estradiol esters by MCF-7 cells incubated under the above conditions, results at least in part, from an esterase-catalyzed exchange reaction. Under conditions where no ester hydrolysis could be detected in the absence of cells, valerate and stearate esters of estradiol were found to be as effective as unesterified estradiol in stimulating esterase synthesis and the incorporation of [3H]thymidine into DNA. These results are consistent with a model in which an intracellular esterase in MCF-7 cells can generate estradiol from an exogenous lipoidal steroid and elicit an estrogen response. PMID:1997120

Katz, J; Levitz, M; Kadner, S S; Finlay, T H

1991-01-01

75

The Papillomavirus E2 proteins.  

PubMed

The papillomavirus E2 proteins are pivotal to the viral life cycle and have well characterized functions in transcriptional regulation, initiation of DNA replication and partitioning the viral genome. The E2 proteins also function in vegetative DNA replication, post-transcriptional processes and possibly packaging. This review describes structural and functional aspects of the E2 proteins and their binding sites on the viral genome. It is intended to be a reference guide to this viral protein. PMID:23849793

McBride, Alison A

2013-07-10

76

The fate and transport of reproductive hormones and their conjugates in the environment (Invited)  

Microsoft Academic Search

Reproductive steroid hormones can disrupt the endocrine system of some species at ng\\/L concentrations. Sources of steroid hormones to the environment include human waste water effluents or manure produced at animal feeding operations (AFOs). Steroid hormones, such as 17beta-estradiol (E2) and estrone (E1), undergo various fate and transport processes, and laboratory studies have shown that they do not persist long

F. X. Casey; S. L. Shrestha; H. Hakk; D. J. Smith; G. L. Larsen; G. Padmanabhan

2009-01-01

77

Distinct Regulation by Steroids of Messenger RNAs for FSHR and CYP19A1 in Bovine Granulosa Cells  

Microsoft Academic Search

Steroidal regulation of gene expression in follicular cells is not completely defined. Granulosa cells from 5 mm bovine follicles were cultured and treated and steady-state mRNA levels determined for FSHR (follicle-stimulating hormone receptor) and CYP19A1 (aromatase). Cells were treated for 5 days with (0.1-300 ng\\/ml) 17beta-estradiol (E2), testosterone (T), or 5alpha-dihydrotestosterone (DHT). FSHR mRNA was increased by T and DHT

Wenxiang Luo; Milo C. Wiltbank

2006-01-01

78

Estrogen promotes the survival and pulmonary metastasis of tuberin-null cells  

Microsoft Academic Search

Lymphangioleiomyomatosis (LAM) is an often fatal disease primarily affecting young women in which tuberin (TSC2)-null cells metastasize to the lungs. The mechanisms underlying the striking female predominance of LAM are unknown. We report here that 17-beta-estradiol (E2) causes a 3- to 5-fold increase in pulmonary metastases in male and female mice, respectively, and a striking increase in circulating tumor cells

Jane J. Yu; Victoria A. Robb; Tasha A. Morrison; Eric A. Ariazi; Magdalena Karbowniczek; Aristotelis Astrinidis; Chunrong Wang; Lisa Hernandez-Cuebas; Laura F. Seeholzer; Emmanuelle Nicolas; Harvey Hensley; V. Craig Jordan; Cheryl L. Walker; Elizabeth P. Henske

2009-01-01

79

Bioassays for estrogenic activity: development and validation of estrogen receptor (ERalpha/ERbeta) and breast cancer proliferation bioassays to measure serum estrogenic activity in clinical studies.  

PubMed

Standard estrogenic prodrugs such as estradiol valerate (E2V) and increasingly popular phytoestrogen formulations are commonly prescribed to improve menopausal health. These drugs are metabolized to numerous bioactive compounds, known or unknown, which may exert combinatorial estrogenic effects in vivo. The aim of this study is to develop and validate estrogen receptor (ER) alpha/ERbeta reporter gene and MCF-7 breast cancer cell proliferation bioassays to quantify serum estrogenic activities in a clinical trial setting. We measured changes in serum estrogenicity following ingestion of E2V and compared this to mass spectrometric measurements of its bioactive metabolites, estrone and 17beta-stradiol. ERalpha bioactivity of the 192 serum samples correlated well (R = 79%) with 17beta-estradiol levels, and adding estrone improved R to 0.83 (likelihood ratio test, P < 0.0001), suggesting that the ERalpha assay reflects summated activity of compounds in serum. ERbeta correlated moderately (R = 0.52) with estrone and 17beta-estradiol, with an estrone/17beta-estradiol coefficient ratio that was twice that of ERalpha, indicating estrone was more active on a molar basis in the ERbeta assay. Unlike the ERalpha and ERbeta bioassays, MCF-7 cell proliferation was driven by 17beta-estradiol, and addition of estrone did not increase the predictive value of the model, suggesting that the driver or drivers for breast cancer cell proliferation were not the same as for ERalpha and ERbeta transactivation. In contrast, a decoction of the traditional Chinese medicinal herb Epimedium pubescens did not induce significant changes in estrogenic bioactivity over baseline. These data indicate that ERalpha/ERbeta reporter gene and MCF-7 breast cancer cell proliferation bioassays reflect different aspects of estrogenic activity and that these assays suggest that the Epimedium formulation tested is unlikely to exert significant estrogenic effects in humans. PMID:19382890

Li, J; Lee, L; Gong, Y; Shen, P; Wong, S P; Wise, Stephen D; Yong, E L

2009-02-01

80

Contrasting Roles of E2F2 and E2F3 in Cardiac Neovascularization  

PubMed Central

Insufficient neovascularization, characterized by poor endothelial cell (EC) growth, contributes to the pathogenesis of ischemic heart disease and limits cardiac tissue preservation and regeneration. The E2F family of transcription factors are critical regulators of the genes responsible for cell-cycle progression and growth; however, the specific roles of individual E2Fs in ECs are not well understood. Here we investigated the roles of E2F2 and E2F3 in EC growth, angiogenesis, and their functional impact on myocardial infarction (MI). An endothelial-specific E2F3-deficient mouse strain VE-Cre; E2F3fl/fl was generated, and MI was surgically induced in VE-Cre; E2F3fl/fl and E2F2-null (E2F2 KO) mice and their wild-type (WT) littermates, VE-Cre; E2F3+/+ and E2F2 WT, respectively. The cardiac function, infarct size, and vascular density were significantly better in E2F2 KO mice and significantly worse in VE-Cre; E2F3fl/fl mice than in their WT littermates. The loss of E2F2 expression was associated with an increase in the proliferation of ECs both in vivo and in vitro, while the loss of E2F3 expression led to declines in EC proliferation. Thus, E2F3 promotes while E2F2 suppresses ischemic cardiac repair through corresponding changes in EC proliferation; and differential targeting of specific E2F members may provide a novel strategy for therapeutic angiogenesis of ischemic heart disease.

Zhou, Junlan; Wu, Min; Xu, Shiyue; Cheng, Min; Ding, Caizhi; Liu, Ye; Yan, Hongbin; Biyashev, Dauren; Kishore, Raj; Qin, Gangjian

2013-01-01

81

Secrets of E2V Technologies CCDs  

Microsoft Academic Search

To complement previously published information on E2V CCDs, we present here some less well-known information about Marconi CCDs. We show details of the performance of deep depletion silicon variants, and discuss other subtleties of performance. We also present an update on L3vision (sub-electron noise) devices, indicating current availability, options, and ongoing development work. Finally, we will give a flavour of

P. R. Jorden; P. Pool; S. M. Tulloch

2004-01-01

82

Secrets of E2V Technologies CCDs  

Microsoft Academic Search

To complement previously published information on E2V CCDs, we present here some less well-known information about Marconi\\u000a CCDs. We show details of the performance of deep depletion silicon variants, and discuss other subtleties of performance.\\u000a We also present an update on L3vision (sub-electron noise) devices, indicating current availability, options, and ongoing\\u000a development work. Finally, we will give a flavour of

Paul R. Jorden; Peter Pool; Simon M. Tulloch

83

Vortices in (e,2e) momentum distributions  

NASA Astrophysics Data System (ADS)

Complete experiments measure all variables associated with atomic processes. Momentum distributions of ejected electrons in pure states, as for (e,2e) measurements, are examples of such complete experiments. All structures seen in such distributions are listed by Briggs and co-workersootnotetextJ. Berakdar and J. S. Briggs, J. Phys. B, 27, 4271 (1994). in 1994. Recently, we pointed out that there is a type of structure not included in the list. It has been shown that momentum distributions image time-dependent wave functions, and such wave functions may contain vortices owing to angular momentum transfer between species involved in the dynamical processes. The vortices are associated with exact zeros at single, isolated points. We have found such zeros in calculated momentum distributions for ion-atom collisions, photoionization, and (e,2e) distributions. By mapping distributions that image time-dependent wave functions we find velocity fields that circulate about exact zeros confirming their vortex structure. The vortices appear as unexpected holes in the (e,2e) momentum distributions. Our calculations suggest that one particular vortex has been observed.ootnotetextA. J. Murray and F. H. Read, Phys. Rev. A, 47, 3724 (1993).

Macek, J. H.; Ovchinnikov, S. Y.; Sternberg, J. B.

2010-03-01

84

Molecular mechanism of inhibition of estrogen-induced cathepsin D gene expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in MCF-7 cells  

SciTech Connect

This report describes how 17{beta}-estradiol (E2) induces cathepsin D gene expression, but is inhibited by the aryl hydrocarbon receptor by disruption of the estrogen receptor/pBC12/S1/pac plasmid complex by interaction with an overlapping xenobiotic responsive element. It was also determined that 2,3,7,8-tetrachlorobenzo-p-dioxin (TCDD) alone does not affect cathepsin D gene expression but can together with E2 to affect the rate of transcription and levels of immunoreactive protein. 85 refs., 6 figs., 2 tabs.

Krishnan, V.; Porter, W.; Santostefano, M.; Wang, Xiahong [Texas A& M Univ., College Station, TX (United States)] [and others

1995-12-01

85

E 2 transition probabilities in 77 Br  

Microsoft Academic Search

77Br has been investigated by the reaction64Ni(16O,p2n?) at 60 MeV. The following mean lives (in parentheses) have been determined by the recoil distance Doppler shift method (energies in keV): 161.9 (718±50 ps), 575.2 (14.2±2.1 ps), 639.0 (14.1±0.8 ps), 782.0 (4.3±0.9 ps), 790.1 (6.2±0.8 ps), 1,273.2 (4.0±1.0 ps), 1,303.0 (4.0±1 ps), 1,480.8 (0.6 ±0.2 ps). The resultingB(E2) values are compared with

H. Schäfer; A. Dewald; A. Gelberg; U. Kaup; K. O. Zell; P. von Brentano

1979-01-01

86

Contrasting roles of E2F2 and E2F3 in endothelial cell growth and ischemic angiogenesis.  

PubMed

The growth of new blood vessels after ischemic injury requires endothelial cells (ECs) to divide and proliferate, and the E2F transcription factors are key regulators of the genes responsible for cell-cycle progression; however, the specific roles of individual E2Fs in ECs are largely unknown. To determine the roles of E2F2 and E2F3 in EC proliferation and the angiogenic response to ischemic injury, hind-limb ischemia was surgically induced in E2F2(-/-) mice, endothelial-specific E2F3-knockout (EndoE2F3(?/?)) mice, and their littermates with wild-type E2F2 and E2F3 expression. Two weeks later, Laser-Doppler perfusion measurements, capillary density, and endothelial proliferation were significantly greater in E2F2(-/-) mice and significantly lower in EndoE2F3(?/?) mice than in their littermates, and EndoE2F3(?/?) mice also developed toe and limb necrosis. The loss of E2F2 expression was associated with increases in the proliferation and G1/S-phase gene expression of isolated ECs, while the loss of E2F3 expression led to declines in these parameters. Thus E2F2 impairs, and endothelial E2F3 promotes, the angiogenic response to peripheral ischemic injury through corresponding changes in EC cell-cycle progression. PMID:23603666

Zhou, Junlan; Cheng, Min; Wu, Min; Boriboun, Chan; Jujo, Kentaro; Xu, Shiyue; Zhao, Ting C; Tang, Yao-Liang; Kishore, Raj; Qin, Gangjian

2013-04-18

87

Synergistic Function of E2F7 and E2F8 is Essential for Cell Survival and Embryonic Development  

PubMed Central

Summary The novel E2f7 and E2f8 family members are thought to function as transcriptional repressors important for the control of cell proliferation. Here we have analyzed the consequences of inactivating E2f7 and E2f8 in mice and show that their individual loss had no significant effect on development. Their combined ablation, however, resulted in massive apoptosis and dilation of blood vessels, culminating in lethality by embryonic day E11.5. A deficiency in E2f7 and E2f8 led to an increase in E2f1 and p53, as well as in many stress-related genes. Homo- and hetero-dimers of E2F7 and E2F8 were found on target promoters, including E2f1. Importantly, loss of either E2f1 or p53 suppressed the massive apoptosis in double mutant embryos. These results identify E2F7 and E2F8 as a unique repressive arm of the E2F transcriptional network that is critical for embryonic development and control of the E2F1-p53 apoptotic axis.

Li, Jing; Ran, Cong; Li, Edward; Gordon, Faye; Comstock, Grant; Siddiqui, Hasan; Cleghorn, Whitney; Chen, Hui-zi; Kornacker, Karl; Pandit, Shusil K.; Khanizadeh, Mehrbod; Weinstein, Michael; Leone, Gustavo; de Bruin, Alain

2008-01-01

88

Synergistic function of E2F7 and E2F8 is essential for cell survival and embryonic development.  

PubMed

The E2f7 and E2f8 family members are thought to function as transcriptional repressors important for the control of cell proliferation. Here, we have analyzed the consequences of inactivating E2f7 and E2f8 in mice and show that their individual loss had no significant effect on development. Their combined ablation, however, resulted in massive apoptosis and dilation of blood vessels, culminating in lethality by embryonic day E11.5. A deficiency in E2f7 and E2f8 led to an increase in E2f1 and p53, as well as in many stress-related genes. Homo- and heterodimers of E2F7 and E2F8 were found on target promoters, including E2f1. Importantly, loss of either E2f1 or p53 suppressed the massive apoptosis in double-mutant embryos. These results identify E2F7 and E2F8 as a unique repressive arm of the E2F transcriptional network that is critical for embryonic development and control of the E2F1-p53 apoptotic axis. PMID:18194653

Li, Jing; Ran, Cong; Li, Edward; Gordon, Faye; Comstock, Grant; Siddiqui, Hasan; Cleghorn, Whitney; Chen, Hui-Zi; Kornacker, Karl; Liu, Chang-Gong; Pandit, Shusil K; Khanizadeh, Mehrbod; Weinstein, Michael; Leone, Gustavo; de Bruin, Alain

2008-01-01

89

Arginine methylation controls growth regulation by E2F-1  

PubMed Central

E2F transcription factors are implicated in diverse cellular functions. The founding member, E2F-1, is endowed with contradictory activities, being able to promote cell-cycle progression and induce apoptosis. However, the mechanisms that underlie the opposing outcomes of E2F-1 activation remain largely unknown. We show here that E2F-1 is directly methylated by PRMT5 (protein arginine methyltransferase 5), and that arginine methylation is responsible for regulating its biochemical and functional properties, which impacts on E2F-1-dependent growth control. Thus, depleting PRMT5 causes increased E2F-1 protein levels, which coincides with decreased growth rate and associated apoptosis. Arginine methylation influences E2F-1 protein stability, and the enhanced transcription of a variety of downstream target genes reflects increased E2F-1 DNA-binding activity. Importantly, E2F-1 is methylated in tumour cells, and a reduced level of methylation is evident under DNA damage conditions that allow E2F-1 stabilization and give rise to apoptosis. Significantly, in a subgroup of colorectal cancer, high levels of PRMT5 frequently coincide with low levels of E2F-1 and reflect a poor clinical outcome. Our results establish that arginine methylation regulates the biological activity of E2F-1 activity, and raise the possibility that arginine methylation contributes to tumourigenesis by influencing the E2F pathway.

Cho, Er-Chieh; Zheng, Shunsheng; Munro, Shonagh; Liu, Geng; Carr, Simon M; Moehlenbrink, Jutta; Lu, Yi-Chien; Stimson, Lindsay; Khan, Omar; Konietzny, Rebecca; McGouran, Joanna; Coutts, Amanda S; Kessler, Benedikt; Kerr, David J; Thangue, Nicholas B La

2012-01-01

90

Evolving intricacies and implications of E2F1 regulation  

Microsoft Academic Search

E2F transcription factors may play a pivotal role in the transcriptional regulation of several cellular processes far beyond the originally described cell cycle and proliferation. Among the six E2F family members, only E2F1 is noted for its role in apoptosis. The pocket protein family members Rb, p107, and p130 act as the main regulators of E2F activity. None- theless, in

SUNEEL D. MUNDLE; GURVEEN SABERWAL

2003-01-01

91

LEF-1 activates the transcription of E2F1  

SciTech Connect

LEF-1 and E2F are both transcription factors involved in cell proliferation, differentiation and apoptosis. The present study shows for the first time that LEF-1 associates with E2F1 and further {beta}-catenin independently activates the E2F-responsive reporter gene by attenuating the interaction between E2F1 and Histone deacetylase 1 (HDAC1), which indicates that LEF-1, except for its function in Wnt signaling, may play a distinct role via activating the transcription of E2F1.

Zhou Fangfang; Zhang Long; Gong Kai; Lu Guangyuan; Sheng Baiyang; Wang Aijun; Zhao Nanming; Zhang Xiufang [State Key Laboratory of Biomembrane and Membrane Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084 (China); Gong Yandao [State Key Laboratory of Biomembrane and Membrane Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084 (China)], E-mail: gongyd@tsinghua.edu.cn

2008-01-04

92

Evidence for cooperativity between E2 binding sites in E2 trans-regulation of bovine papillomavirus type 1.  

PubMed Central

The long control region of bovine papillomavirus type 1 (BPV-1) can function in an orientation- and position-independent manner as an E2-dependent enhancer. Dissection of the long control region has revealed two E2-responsive elements, E2RE1 and E2RE2, which map, respectively, between nucleotides 7611 and 7806 and between nucleotides 7200 and 7386 of the BPV-1 genome. In this study, we have carried out a detailed analysis of E2RE1, which has previously been shown to be involved in the regulation of the BPV-1 promoters P89 and P7940. One characteristic of E2RE1 is the presence of a pair of ACCN6GGT motifs (E2 binding sites) at each end of the element. To determine the contribution of these sites, as well as other sequences within E2RE1, to enhancer function, specific mutations and deletions were generated by oligonucleotide reconstruction. The functional analysis of these mutations confirmed that a pair of E2 binding sites was essential for E2-dependent enhancer activity but also indicated that cooperativity between the motifs at each end of E2RE1 creates a highly responsive element. Isolated ACCN6GGT motif pairs could also act as E2-dependent enhancers but at a significantly reduced level in comparison to the intact element. The sequences between the E2 binding sites in E2RE1 were not required for enhancer function and could actually block the enhancer activity of an isolated pair of E2 binding sites when positioned between the binding sites and the enhancer-deleted simian virus 40 early promoter.

Spalholz, B A; Byrne, J C; Howley, P M

1988-01-01

93

Interplay between Arabidopsis Activating Factors E2Fb and E2Fa in Cell Cycle Progression and Development1[W  

PubMed Central

Eukaryotic E2Fs are conserved transcription factors playing crucial and antagonistic roles in several pathways related to cell division, DNA repair, and differentiation. In plants, these processes are strictly intermingled at the growing zone to produce postembryonic development in response to internal signals and environmental cues. Of the six AtE2F proteins found in Arabidopsis (Arabidopsis thaliana), only AtE2Fa and AtE2Fb have been clearly indicated as activators of E2F-responsive genes. AtE2Fa activity was shown to induce S phase and endoreduplication, whereas the function of AtE2Fb and the interrelationship between these two transcription factors was unclear. We have investigated the role played by the AtE2Fb gene during cell cycle and development performing in situ RNA hybridization, immunolocalization of the AtE2Fb protein in planta, and analysis of AtE2Fb promoter activity in transgenic plants. Overexpression of AtE2Fb in transgenic Arabidopsis plants led to striking modifications of the morphology of roots, cotyledons, and leaves that can be ascribed to stimulation of cell division. The accumulation of the AtE2Fb protein in these lines was paralleled by an increased expression of E2F-responsive G1/S and G2/M marker genes. These results suggest that AtE2Fa and AtE2Fb have specific expression patterns and play similar but distinct roles during cell cycle progression.

Sozzani, Rosangela; Maggio, Caterina; Varotto, Serena; Canova, Sabrina; Bergounioux, Catherine; Albani, Diego; Cella, Rino

2006-01-01

94

Measurement of estrogenic activity in sediments from Haihe and Dagu River, China.  

PubMed

Sediments from two rivers in China, the Haihe and Dagu Rivers, were examined for estrogenic activity using an estrogen receptor (ER)-mediated in vitro bioassay system. ER-active compounds were isolated from sediments by Soxhlet extraction, and the crude extracts were fractionated using a florisil column into three fractions. The estrogenic activity of each extract was detected by measuring luciferase activity in the human breast cancer cell line MCF-7 transfected with a luciferase receptor gene. Significant estrogenic activity was observed in each total extract. The 17beta-estradiol equivalents (E2-EQs) ranged from 8.24 to 95.28 ng E2 g(-1) dw. As a result, the relative estrogenic potencies of three fractions in this study descended in the order of Fraction 3>Fraction 2>Fraction 1. The results of the bioassay analysis indicated the heavy pollution status of these sites with estrogenic contaminants. In this study, five selected chemicals, the natural estrogens 17beta-estradiol (E2) and estrone (E1), and the xeno-estrogens 4-octylphenol (OP), 4-nonylphenol (NP), and Bisphenol A (BPA) were also analyzed using the in vitro bioassay. The estrogenic activity of these chemicals were E2>E1>NP>OP>BPA. PMID:16624408

Song, Maoyong; Xu, Yan; Jiang, Qinting; Lam, Paul K S; O'Toole, Desmond K; Giesy, John P; Jiang, Guibin

2006-04-19

95

Unusual proliferation arrest and transcriptional control properties of a newly discovered E2F family member, E2F-6  

PubMed Central

E2F transcription factors play an important role in the regulation of cell cycle progression. We report here the cloning and characterization of an additional member of this family, E2F-6. E2F-6 lacks pocket protein binding and transactivation domains, and it is a potent transcriptional repressor that contains a modular repression domain at its carboxyl terminus. Overproduction of E2F-6 had no specific effect on cell cycle progression in asynchronously growing Saos2 and NIH 3T3 cells, but it inhibited entry into S phase of NIH 3T3 cells stimulated to exit G0. Taken together, these data suggest that E2F-6 can regulate a subset of E2F-dependent genes whose products are required for entry into the cell cycle but not for normal cell cycle progression.

Gaubatz, Stefan; Wood, Jason G.; Livingston, David M.

1998-01-01

96

The class I bHLH factors E2-2A and E2-2B regulate EMT.  

PubMed

Functional loss of the cell-cell adhesion molecule E-cadherin is an essential event for epithelial-mesenchymal transition (EMT), a process that allows cell migration during embryonic development and tumour invasion. In most carcinomas, transcriptional repression has emerged as the main mechanism responsible for E-cadherin downregulation. Here, we report the identification of class I bHLH factor E2-2 (TCF4/ITF2) as a new EMT regulator. Both isoforms of E2-2 (E2-2A and E2-2B) induce a full EMT when overexpressed in MDCK cells but without affecting the tumorigenic properties of parental cells, in contrast to other EMT inducers, such as Snail1 or class I bHLH E47. E-cadherin repression mediated by E2-2 is indirect and independent of proximal E-boxes of the promoter. Knockdown studies indicate that E2-2 expression is dispensable for maintenance of the EMT driven by Snail1 and E47. Comparative gene-profiling analysis reveals that E2-2 factors induce similar, yet distinct, genetic programs to that induced by E47 in MDCK cells. These results, together with the embryonic expression pattern of Tcf4 and E2A (which encodes E12/E47), support a distinct role for E2-2 and suggest an interesting interplay between E-cadherin repressors in the regulation of physiological and pathological EMT processes. PMID:19295128

Sobrado, Verónica R; Moreno-Bueno, Gema; Cubillo, Eva; Holt, Liam J; Nieto, M Angela; Portillo, Francisco; Cano, Amparo

2009-04-01

97

Possible Role of E2F in Rat Mammary Carcinogenesis.  

National Technical Information Service (NTIS)

Upregulation of the E2F family of transcription factors has been suggested to be commonly associated with a neoplastic phenotype. To understand the consequences of altered E2F activity in cancer, I have used two model systems: a rat mammary tumor assay an...

P. J. Farnham T. Lee

1999-01-01

98

Neck and Back Pain in E-2C HAWKEYE Aircrew.  

National Technical Information Service (NTIS)

The purpose of this study was to determine select characteristics of neck and back symptoms among E-2C Hawkeye aircrew. One hundred eighty-five E-2C aircrew volunteered to complete a neck and back pain and symptoms survey. The mean (+- SD) age and flight ...

T. A. Loomis J. A. Hodgdon L. Hervig W. K. Prusacyzk

1999-01-01

99

The RB-E2F1 Pathway Regulates Autophagy  

PubMed Central

Autophagy is a protective mechanism that renders cells viable in stressful conditions. Emerging evidence suggests that this cellular process is also a tumor suppressor pathway. Previous studies showed that cyclin-dependent kinase inhibitors (CDKI) induce autophagy. Whether retinoblastoma protein (RB), a key tumor suppressor and downstream target of CDKIs, induces autophagy is not clear. Here, we show that RB triggers autophagy and that the RB activators p16INK4a and p27/kip1 induce autophagy in an RB-dependent manner. RB binding to E2 transcription factor (E2F) is required for autophagy induction and E2F1 antagonizes RB-induced autophagy, leading to apoptosis. Downregulation of E2F1 in cells results in high levels of autophagy. Our findings indicate that RB induces autophagy by repressing E2F1 activity. We speculate that this newly discovered aspect of RB function is relevant to cancer development and therapy.

Jiang, Hong; Martin, Vanesa; Gomez-Manzano, Candelaria; Johnson, David G.; Alonso, Marta; White, Erin; Xu, Jing; McDonnell, Timothy J.; Shinojima, Naoki; Fueyo, Juan

2011-01-01

100

E2F and its developmental regulation in Xenopus laevis.  

PubMed

The transcription factor E2F has been implicated in cell cycle control by virtue of its association with cyclins, cyclin-dependent kinases, and pRb-related tumor suppressor gene products. Eggs and embryos from the frog Xenopus laevis have been used to investigate the characteristics of E2F-like molecules in the Xenopus cell cycle and throughout early development. We find multiple E2F species in Xenopus eggs, at least one of which is modified by phosphorylation. The vast majority of E2F remains in the free form throughout the very early embryonic cell cycle, and it also remains predominantly free until some time after the mid-blastula transition, the onset of zygotic transcription. At this time, E2F complexes significantly to pRb but not to cdk2, although cdk2 binding is found in tissue culture cells from a very advanced stage in embryogenesis. This suggests that the complexing of E2F to cyclins, cyclin-dependent kinases, and tumor suppressor gene products may be controlled separately in early Xenopus development. Thus, the association of E2F with other molecules may not result solely from processes affecting cell cycle progression but may also reflect developmental and differentiation cues. PMID:8007993

Philpott, A; Friend, S H

1994-07-01

101

E2F and its developmental regulation in Xenopus laevis.  

PubMed Central

The transcription factor E2F has been implicated in cell cycle control by virtue of its association with cyclins, cyclin-dependent kinases, and pRb-related tumor suppressor gene products. Eggs and embryos from the frog Xenopus laevis have been used to investigate the characteristics of E2F-like molecules in the Xenopus cell cycle and throughout early development. We find multiple E2F species in Xenopus eggs, at least one of which is modified by phosphorylation. The vast majority of E2F remains in the free form throughout the very early embryonic cell cycle, and it also remains predominantly free until some time after the mid-blastula transition, the onset of zygotic transcription. At this time, E2F complexes significantly to pRb but not to cdk2, although cdk2 binding is found in tissue culture cells from a very advanced stage in embryogenesis. This suggests that the complexing of E2F to cyclins, cyclin-dependent kinases, and tumor suppressor gene products may be controlled separately in early Xenopus development. Thus, the association of E2F with other molecules may not result solely from processes affecting cell cycle progression but may also reflect developmental and differentiation cues. Images

Philpott, A; Friend, S H

1994-01-01

102

Canonical and Atypical E2Fs Regulate the Mammalian Endocycle  

PubMed Central

SUMMARY The endocycle is a variant cell cycle consisting of successive DNA synthesis and Gap phases that yield highly polyploid cells. Although essential for metazoan development, relatively little is known about its control or physiologic role in mammals. Using novel lineage-specific cre mice we identified two opposing arms of the E2F program, one driven by canonical transcription activation (E2F1, E2F2 and E2F3) and the other by atypical repression (E2F7 and E2F8), that converge on the regulation of endocycles in vivo. Ablation of canonical activators in the two endocycling tissues of mammals, trophoblast giant cells in the placenta and hepatocytes in the liver, augmented genome ploidy, whereas ablation of atypical repressors diminished ploidy. These two antagonistic arms coordinate the expression of a unique G2/M transcriptional program that is critical for mitosis, karyokinesis and cytokinesis. These results provide in vivo evidence for a direct role of E2F family members in regulating non-traditional cell cycles in mammals.

Chen, Hui-Zi; Ouseph, Madhu M.; Li, Jing; Pecot, Thierry; Chokshi, Veda; Kent, Lindsey; Bae, Sooin; Byrne, Morgan; Duran, Camille; Comstock, Grant; Trikha, Prashant; Mair, Markus; Senapati, Shantibhusan; Martin, Chelsea K.; Gandhi, Sagar; Wilson, Nicholas; Liu, Bin; Huang, Yi-Wen; Thompson, John C.; Raman, Sundaresan; Singh, Shantanu; Leone, Marcelo; Machiraju, Raghu; Huang, Kun; Mo, Xiaokui; Fernandez, Soledad; Kalaszczynska, Ilona; Wolgemuth, Debra J.; Sicinski, Piotr; Huang, Tim; Jin, Victor; Leone, Gustavo

2012-01-01

103

Gamma-ray spectrometer onboard Chang'E-2  

NASA Astrophysics Data System (ADS)

Chang'E-2 gamma-ray spectrometer (GRS) is included in the payload of Chinese second lunar mission Chang'E-2 that has been launched in October 2010. Specific objectives of the GRS are to map abundance of O, Si, Fe, Ti, U, Th, K, and, perhaps, Mg, Al, and Ca, to depth of about 20 cm. The energy resolution and detection efficiency were improved compared with Chang'E-1 GRS. We will describe the design of GRS, which used LaBr3 for its main detector, and present its performance in this paper. Moreover, the initial result of Chang'E-2 GRS is reported.

Ma, T.; Chang, J.; Zhang, N.; Jian, W.; Cai, M. S.; Gong, Y. Z.; Tang, H. S.; Zhang, R. J.; Wang, N. S.; Yu, M.; Mao, J. P.; Hu, Y. M.; Xu, A. A.; Zhu, M. H.

2013-10-01

104

Radiation hardness of COTS EPROMs and E2PROMs  

NASA Astrophysics Data System (ADS)

This paper examines and compares the effects of exposing commercial, off the shelf erasable programmable read-only memory (EPROM) and electrically erasable programmable read-only memory (E2PROM) components to gamma rays. Results obtained for CMOS-based EPROM (NM27C010) and E2PROM (NM93CS46) components provide evidence that EPROMs have a greater radiation hardness than E2PROMs. Moreover, the changes in EPROMs are reversible, and after erasure and reprogramming all EPROM components restore their functionality. On the other hand, changes in E2PROMs are irreversible. The obtained results are analyzed and interpreted on the basis of gamma ray interaction with the CMOS structure.

Vujisi?, Miloš; Stankovi?, Koviljka; Doli?anin, Edin; Osmokrovi?, Predrag

105

E2B(R3) OID Information Paper  

Center for Drug Evaluation (CDER)

Text Version... org INFORMATION PAPER Use of OIDs & UUIDs in E2B(R3) 07 November 2011 ... These are also explained in this paper. Note ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

106

Possibility of direct E2 capture in /sup 21/Ne  

SciTech Connect

It is shown that the partial cross section for the E2 transition at 6415 keV in /sup 21/Ne emitted following thermal neutron capture is extremely large if it is a result of resonance capture. The possibility of a direct E2 contribution is explored. The cross section can be accounted for by direct capture if the effective charge appropriate for low energy electric quadrupole transitions is used.

Prestwich, W.V.; Kennett, T.J.

1984-07-01

107

E2E Testing and Evaluation of High Assurance Systems  

Microsoft Academic Search

Summary DoD E2E Testing and Evaluation (T&E) technology for high assurance system has evolved from specification and analysis of thin threads, through system scenarios, and to the scenario-driven system engineering including reliability, security, and safety assurance, as well as dynamic verification and validation. Currently, E2E T&E technology is entering the fourth generation and being applied to the development and verification

Ray Paul; W. T. Tsai; Y. Chen; C. Fan; Z. Cao; H. Huang

2006-01-01

108

Gastric estradiol-17? (E2) and liver ER? correlate with serum E2 in the cholestatic male rat.  

PubMed

Cholestasis is associated with changes in hepatic cholesterol metabolism and serum estrogen levels. Ueyama and colleagues reported that the gastric estradiol-17? (E2) level in the portal vein is several times higher than that in the artery. This study aimed to clarify the relationships between gastric E2, hepatic estrogen receptor (ER) ? and cholesterol metabolism in cholestatic male rats induced by bile duct ligation (BDL). After BDL, serum E2 levels in the portal vein and artery were measured by ELISA. The gene expression of gastric estrogen-synthesizing enzymes and various hepatic enzymes for cholesterol metabolism were measured by real-time RT-PCR, and gastric aromatase and hepatic ER? proteins were determined by immunohistochemistry and western blotting. Portal E2 levels increased by 4.9, 5.0, and 3.6 times that of controls at 2 days after BDL (BDL2d), BDL4d, and BDL7d respectively. The change in arterial E2 levels was positively correlated with that in the portal vein. Under these conditions, the expression of hepatic Ers1 (ER?) mRNA and protein was significantly reduced in a negative correlation with serum E2 levels in the portal vein after BDL. The expression of hepatic male-specific cytochrome P450 (CYP) genes Cyp2c55 and Cyp3a2 decreased and female-specific Cyp2c12 increased after BDL. It is postulated that the increase in gastric E2 levels, which occurs after BDL, results in the reduction of hepatic ER?, the elevation of arterial E2 level and leads to cholesterol metabolism becoming sex steroid dependent. PMID:23881936

Kobayashi, Hiroto; Yoshida, Saori; Sun, Ying-Jie; Shirasawa, Nobuyuki; Naito, Akira

2013-09-06

109

The role of prostaglandin E2 in endometriosis.  

PubMed

Endometriosis is a leading cause of infertility in women of reproductive age. It involves the occurrence of endometrial tissue outside the uterine endometrium, mainly in the peritoneal cavity. Prostaglandin E(2) is up regulated in the peritoneal cavity in endometriosis and is produced by macrophages and ectopic endometrial cells. This prostaglandin is involved in the pathophysiology of the disease and elicits cell signals via four receptor types. Prostaglandin E(2) increases estrogen synthesis by up regulating steroidogenic acute regulatory protein (StAR) and aromatase. It inhibits apoptosis and up regulates fibroblast growth factor-9 (FGF-9) promoting cell proliferation. Prostaglandin E(2) affects leukocyte populations and promotes angiogenesis through its effect on estrogen and up regulation of vascular endothelial growth factor (VEGF). Dienogest is a synthetic progestin targeting expression of genes involved in prostaglandin synthesis. PMID:22003899

Sacco, Keith; Portelli, Mark; Pollacco, Joël; Schembri-Wismayer, Pierre; Calleja-Agius, Jean

2011-10-17

110

A comparative pharmacokinetic study of micronized estradiol valerate administered alone and in combination with medroxyprogesterone acetate in postmenopausal women.  

PubMed

The objective of this study was to evaluate a possible pharmacokinetic interaction between 17beta-estradiol (E2) and medroxyprogesterone (MP) when administered together in a combined tablet because both hormones have common metabolic routes of biotransformation. The study assessed the mean pharmacokinetics parameters of E2 found after 1-dose administration of 2 different tablets containing E2, 1 containing 2 mg of micronized 17beta-estradiol valerate (E2V) and the other, administered after 2 weeks, 2 mg of E2V in combination with 5 mg of medroxyprogesterone acetate (MPA). The subjects were 15 healthy postmenopausal women with normal laboratory and clinic tests. The study was randomized, double blind, crossover, with 2 periods and 2 sequences. The blood samples were obtained at 0, 1, 2, 3, 4, 6, 8, 10, 12, and 24 hours after each administration. The E2 serum concentrations were determined by electrochemoluminiscence assay. From these data, the following pharmacokinetic parameters were calculated for E2 alone and E2 in combination with MPA (E2V/MPA): Cmax = 104.89 +/- 26.96, 103.27 +/- 44.40; AUC0-24 =1900.30 +/- 392.23, 1783.70 +/- 756.39; AUC0-infinity = 5576.06 +/- 4065.87, 5317.89 +/- 3702.54; ka = 1.06 +/- 0.31, 1.09 +/- 0.13; t1/2 = 35.65 +/- 20.62, 36.12 +/- 18.04; MRT = 16.29 +/- 8.77, 16.27 +/- 4.88; V/F = 16.29 +/- 8.76, 16.27 +/- 4.88. No significant differences between the pharmacokinetic parameters of E2 and E2/MPA were found, which led us to conclude that there is no pharmacokinetic interaction. PMID:15385829

Saavedra, Iván; León, Jorge; Prado, Jaime; Sánchez, M Pilar; López, Fernando; Gaete, Leonardo

2004-10-01

111

Resetting of peripheral circadian clock by prostaglandin E2  

Microsoft Academic Search

In mammals, the master circadian pacemaker is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is thought to drive peripheral oscillators by controlling neuronal and humoral signals that can entrain the peripheral clocks. Here, we show that prostaglandin E2 (PGE2), a proinflammatory compound known to have diverse biological effects, is able to act as an in vivo

Yoshiki Tsuchiya; Itsunari Minami; Hiroshi Kadotani; Eisuke Nishida

2005-01-01

112

Preparation of the Major Urinary Metabolite of (-)-Prostaglandin E2  

PubMed Central

The best way to measure whole body production of the locally acting hormone prostaglandin E2 (PGE2) is to assess the accumulation of the major urinary metabolite, PGE2 U M. A practical preparation of this delicate diacid is described. This synthetic PGE2UM will enable production of the antibodies that will be used to quantify this key metabolite.

Taber, Douglass F.; Gu, Peiming

2009-01-01

113

E-2D advanced hawkeye: primary flight display  

Microsoft Academic Search

This paper is a response to the challenge of providing a large area avionics display for the E-2D AHE aircraft. The resulting display design provides a pilot with high-resolution visual information content covering an image area of almost three square feet (Active Area of Samsung display = 33.792cm x 27.0336 cm = 13.304\\

Paul W. Paolillo; Ragini Saxena; Jonathan Garruba; Sanjay Tripathi; Randy Blanchard

2006-01-01

114

(e,2e) ionization studies of diatomic & triatomic molecules  

Microsoft Academic Search

(e,2e) studies yield the most detailed experimental data on electron impact ionization of atomic & molecular targets for comparison to quantum collision theories. Coincidence techniques are here used to measure the probability of ionization as a function of the incident electron scattering angle and angle of the electron ejected from the target. In Manchester we study this process at low

Kate Nixon; Andrew Murray; Christian Kaiser; Ola Al-Hagan; James Colgan; Don Madison

2009-01-01

115

Native E2F\\/RBF Complexes Contain Myb-Interacting Proteins and Repress Transcription of Developmentally Controlled E2F Target Genes  

Microsoft Academic Search

The retinoblastoma tumor suppressor protein (pRb) regulates gene transcription by binding E2F transcription factors. pRb can recruit several repressor complexes to E2F bound promoters; however, native pRb repressor complexes have not been isolated. We have purified E2F\\/RBF repressor complexes from Drosophila embryo extracts and characterized their roles in E2F regulation. These complexes contain RBF, E2F, and Myb-interacting proteins that have

Michael Korenjak; Barbie Taylor-Harding; Ulrich K. Binné; John S. Satterlee; Olivier Stevaux; Rein Aasland; Helen White-Cooper; Nick Dyson; Alexander Brehm

2004-01-01

116

A structurally unique E2-binding domain activates ubiquitination by the ERAD E2, Ubc7p, through multiple mechanisms.  

PubMed

Cue1p is an integral component of yeast endoplasmic reticulum (ER)-associated degradation (ERAD) ubiquitin ligase (E3) complexes. It tethers the ERAD ubiquitin-conjugating enzyme (E2), Ubc7p, to the ER and prevents its degradation, and also activates Ubc7p via unknown mechanisms. We have now determined the crystal structure of the Ubc7p-binding region (U7BR) of Cue1p with Ubc7p. The U7BR is a unique E2-binding domain that includes three ?-helices that interact extensively with the "backside" of Ubc7p. Residues essential for E2 binding are also required for activation of Ubc7p and for ERAD. We establish that the U7BR stimulates both RING-independent and RING-dependent ubiquitin transfer from Ubc7p. Moreover, the U7BR enhances ubiquitin-activating enzyme (E1)-mediated charging of Ubc7p with ubiquitin. This demonstrates that an essential component of E3 complexes can simultaneously bind to E2 and enhance its loading with ubiquitin. These findings provide mechanistic insights into how ubiquitination can be stimulated. PMID:23665230

Metzger, Meredith B; Liang, Yu-He; Das, Ranabir; Mariano, Jennifer; Li, Shengjian; Li, Jess; Kostova, Zlatka; Byrd, R Andrew; Ji, Xinhua; Weissman, Allan M

2013-05-09

117

Expression of the estrogen-inducible EGFP gene in aromatase-null mice reveals differential tissue responses to estrogenic compounds.  

PubMed

Aromatase is an enzyme responsible for the conversion of androgen to estrogen. We genetically engineered an aromatase-deficient mouse (Ar(-/-) mouse) to express an enhanced green fluorescent protein (EGFP) gene in the uterus, ovary, adrenal and pituitary glands in a 17beta-estradiol (E2)-inducible manner. In this study, we analyzed estrogenic activities of diethylstilbestrol, genistein, daidzein and E2 in the Ar(-/-) tissues by using the EGFP expression as an indicator. These analyses manifest differential responses of the tissues to the compounds and also allow to determine the relative estrogenic potency of the compounds to that of E2 in vivo. Furthermore, analyses of the EGFP expression in ERalpha-deficient mice suggested that the expression is ERalpha-dependent in the uterus and pituitary gland. In conclusion, the Ar(-/-) mouse carrying the E2-inducible EGFP gene is a valuable tool for quantitative analyses of natural and synthetic estrogenic compounds in vivo. PMID:15607536

Toda, Katsumi; Hayashi, Yoshihiro; Okada, Teruhiko; Morohashi, Ken-ichirou; Saibara, Toshiji

2005-01-14

118

The ancient function of RB-E2F Pathway: insights from its evolutionary history  

PubMed Central

Background The RB-E2F pathway is conserved in most eukaryotic lineages, including animals and plants. E2F and RB family proteins perform crucial functions in cycle controlling, differentiation, development and apoptosis. However, there are two kinds of E2Fs (repressive E2Fs and active E2Fs) and three RB family members in human. Till now, the detail evolutionary history of these protein families and how RB-E2F pathway evolved in different organisms remain poorly explored. Results We performed a comprehensive evolutionary analysis of E2F, RB and DP (dimerization partners of E2Fs) protein family in representative eukaryotic organisms. Several interesting facts were revealed. First, orthologues of RB, E2F, and DP family are present in several representative unicellular organisms and all multicellular organisms we checked. Second, ancestral E2F, RB genes duplicated before placozoans and bilaterians diverged, thus E2F family was divided into E2F4/5 subgroup (including repressive E2Fs: E2F4 and E2F5) and E2F1/2/3 subgroup (including active E2Fs: E2F1, E2F2 and E2F3), RB family was divided into RB1 subgroup (including RB1) and RBL subgroup (including RBL1 and RBL2). Third, E2F4 and E2F5 share more sequence similarity with the predicted E2F ancestral sequence than E2F1, E2F2 and E2F3; E2F4 and E2F5 also possess lower evolutionary rates and higher purification selection pressures than E2F1, E2F2 and E2F3. Fourth, for RB family, the RBL subgroup proteins possess lower evolutionary rates and higher purification selection pressures compared with RB subgroup proteins in vertebrates, Conclusions Protein evolutionary rates and purification selection pressures are usually linked with protein functions. We speculated that function conducted by E2F4/5 subgroup and RBL subgroup proteins might mainly represent the ancient function of RB-E2F pathway, and the E2F1/2/3 subgroup proteins and RB1 protein might contribute more to functional diversification in RB-E2F pathway. Our results will enhance the current understanding of RB-E2F pathway and will also be useful to further functional studies in human and other model organisms. Reviewers This article was reviewed by Dr. Pierre Pontarotti, Dr. Arcady Mushegian and Dr. Zhenguo Lin (nominated by Dr. Neil Smalheiser).

2010-01-01

119

The XRS Microcalorimeter on Astro-E2  

Microsoft Academic Search

The XRS microcalorimeter will be launched in 2005 as part of the Astro-E2 mission. It will cover the energy band from 0.3 to 10 keV with a nearly constant energy resolution of 6.0 eV and a peak effective area of 200 cm2 at 1.5 keV. The XRS will provide unprecedented throughput and resolving power, particularly at high energies. Detailed spectral

J. Cottam; K. R. Boyce; G. V. Brown; R. Fujimoto; T. Furusho; Y. Ishisaki; R. L. Kelley; C. A. Kilbourne; D. McCammon; K. Mitsuda; U. Morita; F. S. Porter; T. Saab; Y. Takai; M. Yamamoto

2005-01-01

120

The E2/M1 ratio in ? photoproduction  

NASA Astrophysics Data System (ADS)

New high-precision measurements of p(?-->,?) and p(?-->,?) cross sections and beam asymmetries have been combined with other polarization ratios in a simultaneous analysis of both reactions. Compton scattering has provided two important new constraints on the photo-pion amplitude. The E2/M1 mixing ratio for the N-->? transition extracted from this analysis is EMR=-3.0%+/-0.3(stat+sys)+/-0.2(model).

Sandorfi, A. M.; Blanpied, G.; Blecher, M.; Caracappa, A.; Djalali, C.; Giordano, G.; Hicks, K.; Hoblit, S.; Khandaker, M.; Kistner, O. C.; Kuczewski, A.; Lowry, M.; Lucas, M.; Matone, G.; Miceli, L.; Preedom, B.; Rebreyend, D.; Schaerf, C.; Sealock, R. M.; Ströher, H.; Thorn, C. E.; Thornton, S. T.; Tonnison, J.; Whisnant, C. S.; Zhang, H.; Zhao, X.

1998-02-01

121

Polarization effect in (e, 2e) collisions of argon  

NASA Astrophysics Data System (ADS)

Calculations of the triple differential cross section (TDCS) for electron impact ionization of the Ar(2p) orbital in a highly asymmetric geometry, using modified distorted wave Born approximation (DWBA) methods, are reported. The role of the polarization effect in (e, 2e) collisions of Ar(2p) is considered in the calculations, and the calculated results shows that the polarization potential is particularly important.

Hu, Xiao-Ying; Zhou, Ya-Jun; Ke, You-Qi; Nan, Guang-Jun

2005-01-01

122

Endoatmospheric/Exoatmospheric Interceptor (E2 I) Program  

SciTech Connect

An overview is given of the Endoatmospheric/Exoatmospheric Interceptor (E2 I) Program. The overall objective of the program is to develop an interceptor to support the endoatmospheric mission of SDI Organization National Missile Defense, while its primary technical objective is to develop the hardware and software required to demonstrate the deployable interceptor that can perform onboard target cluster track and target selection. The background, modes of operation, concept of operation, basis for onboard target selection, and program acquisition are discussed.

Sherer, A.D.; Reeves, W.C. Jr. (U.S. Army, Strategic Defense Command, Huntsville, AL (United States))

1992-05-01

123

Urodynamic effects of estradiol (E 2 ) in ovariectomized (ovx) rats  

Microsoft Academic Search

Whether estrogens have a beneficial effect in the urinary bladder to prevent or to delay occurrence of urinary bladder incontinence\\u000a is an open question. Good animal models are missing. Therefore, in ovariectomized (ovx) rats we studied the effects of estradiol\\u000a (E2) administered with food for 3 mo on urodynamic properties of the urinary bladder and the urethra. A biluminal catheter

D. Seidlová-Wuttke; A. Schultens; H. Jarry; W. Wuttke

2004-01-01

124

Time-resolved ultrafast electron (e,2e) momentum spectroscopy  

NASA Astrophysics Data System (ADS)

The (e,2e) process is analyzed for the case of an ultrafast electron pulse incident upon a target prepared in a time-varying, coherent superposition of states. Conditions under which time-resolved target momentum densities can be obtained from experimental measurements are discussed. Results for coherent electronic motions in both the H atom and the H2+ molecule are used to illustrate the capability of an ultrafast electron pulse to image time-dependent target electron dynamics.

Shao, Hua-Chieh; Starace, Anthony F.

2013-05-01

125

The E2/M1 ratio in {Delta} photoproduction  

SciTech Connect

New high-precision measurements of p({rvec {gamma}}, {pi}) and p({rvec {gamma}}, {gamma}) cross sections and beam asymmetries have been combined with other polarization ratios in a simultaneous analysis of both reactions. The E2/M1 mixing ratio for the n {r_arrow} {Delta} transition extracted from this analysis is EMR = {minus}3.0% {+-} 0.3 (stat+sys) {+-} 0.2 (model).

Hoblit, S. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.]|[Univ. of Virginia, Charlottesville, VA (United States). Dept. of Physics; Blanpied, G. [Univ. of South Carolina, Columbia, SC (United States). Dept. of Physics; Blecher, M. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Physics Dept.] [and others; LEGS Collaboration

1997-10-01

126

The E2/M1 ratio in {delta} photoproduction  

SciTech Connect

New high-precision measurements of p({gamma}-vector,{pi}) and p({gamma}-vector,{gamma}) cross sections and beam asymmetries have been combined with other polarisation ratios in a simultaneous analysis of both reactions. The E2/M1 mixing ratio for the N{yields}{delta} transition extracted from this analysis is EMR=-3.0%{+-}0.3(stat+sys){+-}0.2 (model)

Hoblit, S. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Department of Physics, University of Virginia, Charlottesville, Virginia 22901 (United States); Blanpied, G.; Djalali, C.; Lucas, M.; Preedom, B.; Rebreyend, D.; Whisnant, C. S. [Department of Physics, University of South Carolina, Columbia, South Carolina 29208 (United States); Blecher, M.; Zhao, X. [Physics Department, Virginia Polytechnic Inst. and SU, Blacksburg, Virginia 24061 (United States); Caracappa, A.; Kistner, O. C.; Kuczewski, A.; Lowry, M.; Sandorfi, A. M.; Thorn, C. E. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Giordano, G.; Matone, G. [INFN-Laboratori Natzionali di Frascati, Frascati (Italy); Hicks, K.; Zhang, H. [Department of Physics, Ohio University, Athens, Ohio 45701 (United States); Khandaker, M. [Physics Department, Virginia Polytechnic Inst. and SU, Blacksburg, Virginia 24061 (United States); Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)] (and others)

1997-05-20

127

Secrets of E2V Technologies CCDs (ex Marconi CCDs)  

Microsoft Academic Search

To complement previously published information on E2V CCDs, we present here some less well-known information about Marconi CCDs. We show details of the performance of deep depletion silicon variants, and discuss other subtleties ofperformance. We also present an update on L3vision (sub-electron noise) devices, indicating current availability, options, and ongoing development work. Finally, we will give a flavour of the

Paul R. Jorden; Peter Pool; Simon M. Tulloch

2002-01-01

128

Secrets of E2V Technologies CCDs (ex Marconi CCDs)  

Microsoft Academic Search

To complement previously published information on E2V CCDs, we present here some less well-known information about Marconi\\u000a CCDs. We show details of the performance of deep depletion silicon variants, and discuss other subtleties of performance.\\u000a We also present an update on L3vision (sub-electron noise) devices, indicating current availability, options, and ongoing\\u000a development work. Finally, we will give a flavour of

Paul R. Jorden; Peter Pool; Simon M. Tulloch

2002-01-01

129

Cadmium (e,2e) Experiments in the Autoionizing Region  

NASA Astrophysics Data System (ADS)

We recently completed a comprehensive set(N.L.S. Martin, R.P. Bauman and M. Wilson, submitted to Phys.Rev.A.) of (e,2e) measurements in the Cd 4d^95s^25p autoionizing region, with incident electron energy of 150 eV and scattering angles 2^circ?18^circ. The sum and difference of k_ej=±hat k pairs of (e,2e) energy spectra (N.L.S. Martin, D.B. Thompson, R.P. Bauman and M. Wilson, Phys. Rev. A 50), 3878 (1994). were compared with plane wave Born calculations. The calculated shape of the spectra agreed with experiment if phase corrections, independent of scattering angle, were made to ionization amplitudes, but spectral magnitudes differed by up to a factor of three. We have begun a series of experiments to monitor the phase correction as a function of incident electron energy for fixed momentum transfer, and we are also investigating the differences between (e,2e) spectra for equal angles either side of the momentum transfer axis. In a separate experiment we are measuring the cadmium beam profile in order to to improve beam management.

Bauman, R. P.; Martin, N. L. S.; Martin, C. A.; Wilson, M.

1998-05-01

130

E2F-1 binding affinity for pRb is not the only determinant of the E2F-1 activity  

PubMed Central

E2F-1 is the major cellular target of pRB and is regulated by pRB during cell proliferation. Interaction between pRB and E2F-1 is dependent on the phosphorylation status of pRB. Despite the fact that E2F-1 and pRB have antagonistic activities when they are overexpressed, the role of the E2F-1-pRB interaction in cell growth largely remains unknown. Ideally, it would be better to study the properties of a pRB mutant that fails to bind to E2F, but retains all other activities. To date, no pRB mutation has been characterized in sufficient detail to show that it specifically eliminates E2F binding but leaves other interactions intact. An alternative approach to this issue is to ask whether mutations that change E2F proteins binding affinity to pRB are sufficient to change cell growth in aspect of cell cycle and tumor formation. Therefore, we used the E2F-1 mutants including E2F-1/S332-7A, E2F-1/S375A, E2F-1/S403A, E2F-1/Y411A and E2F-1/L132Q that have different binding affinities for pRB to better understand the roles of the E2F-1 phosphorylation and E2F-1-pRB interaction in the cell cycle, as well as in transformation and gene expression. Data presented in this study suggests that in vivo phosphorylation at amino acids 332-337, 375 and 403 is important for the E2F-1 and pRB interaction in vivo. However, although E2F-1 mutants 332-7, 375 and 403 showed similar binding affinity to pRB, they showed different characteristics in transformation efficiency, G0 accumulation, and target gene experiments.

Sahin, Fikret; Sladek, Todd L.

2010-01-01

131

Effects of 8-prenylnaringenin on the hypothalamo-pituitary-uterine axis in rats after 3-month treatment.  

PubMed

Phytoestrogens are increasingly consumed in artificially high doses as herbal preparations and nutritional supplements. The flavanone 8-prenylnaringenin (8PN) is a potent phytoestrogen, but its benefits and risks after long-term application are poorly identified. Therefore, we tested two doses of 8PN and 17beta-estradiol-3-benzoate (E2B) (effective doses: 6.8 and 68.4 mg/kg body weight (BW) of 8PN, and 0.17 and 0.7 mg/kg BW of 17beta-estradiol (E2)) and compared their effects on uterine weight, pituitary hormones (LH, FSH and prolactin) and the expression of estrogen-regulated genes and of estrogen receptor (ER)alpha and ERbeta in the hypothalamus, pituitary and uterus. Both doses of E2 and the high dose of 8PN suppressed serum LH and FSH, and stimulated serum prolactin levels, uterine weight, and progesterone receptor, insulin-like growth factor I and complement protein C3 mRNA transcripts. In the preoptic and the mediobasal areas of the hypothalamus, all treatments had negligible effects on ERalpha and ERbeta and gonadotropin-releasing hormone (GnRH) receptor gene expression, while ERbeta and GnRH receptor transcripts in the anterior pituitary were reduced under both E2 doses and the high 8PN dose. The mRNA concentrations of the LHalpha and -beta subunits in the pituitary were suppressed by E2 and 8PN. In summary, 8PN had very similar though milder effects than E2 on all tested parameters. Inhibition of climacteric complaints by E2 takes place in the hypothalamus, where it inhibits the overactive GnRH pulse generator. Hence, 8PN may be used to inhibit climacteric symptoms effectively. Human pharmacologic studies will show whether the stimulatory effect on the uterus that was found in the present animal model would require the concomitant administration of progestins to prevent endometrial overstimulation. PMID:16522720

Christoffel, J; Rimoldi, G; Wuttke, W

2006-03-01

132

Reduced Probabilities of E2-Transitions in {sup 174}Yb  

SciTech Connect

This paper describes the ground (gr) and exited states of even-even deformed nuclei with a phenomenological model, which takes into account the mixing of gr states, 0{sub n}{sup +}({beta}{sub n})-, 2{sub n}{sup +}({gamma}{sub n})- and {Kappa}{sup {pi}} 1{sub n}{sup +}- rotational bands. The calculation has been done for the isotope Yb. The energy spectra are found to be consistent with the energies from experimental data. The reduced probabilities of the electric quadrupole E2-transitions from {beta}{sub n} and {gamma}{sub n} band states are calculated and agree quite well with the experimental values.

Okhunov, A. A. [Quantum Science Center Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Institute for Nuclear Physics, Academy Science of Uzbekistan, 100214 Tashkent (Uzbekistan); Kassim, Hasan Abu [Quantum Science Center Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2011-03-30

133

The Astro-E2\\/XRS-2 helium insert system  

Microsoft Academic Search

The X-ray Spectrometer (XRS-2) instrument on the Japanese Space Agency (JAXA) Astro-E2 spacecraft will measure faint X-ray emissions in the energy range of 0.2–10keV. A square array of 32 X-ray microcalorimeters used will be able to distinguish individual photons to better than 10eV at 6keV, with a quantum efficiency near 100%. The detectors are cooled to 60mK by means of

P. J. Shirron; M. J. DiPirro; J. Panek; R. Kelley; K. Mitsuda; R. Fujimoto; M. Hirabayashi; D. McCammon

2006-01-01

134

B-lymphocyte development is regulated by the combined dosage of three basic helix-loop-helix genes, E2A, E2-2, and HEB.  

PubMed Central

B-lymphocyte development requires the basic helix-loop-helix proteins encoded by the E2A gene. In this study, the control mechanism of E2A was further explored by disruption of the E2A-related genes, E2-2 and HEB. In contrast to E2A, E2-2 and HEB are not essential for the establishment of the B-cell lineage. However, both E2-2 and HEB are required for the generation of the normal numbers of pro-B cells in mouse embryos. Breeding tests among mice carrying different mutations revealed that E2-2 and HEB interact with E2A in many developmental processes including generation of B cells. Specifically, mice transheterozygous for any two mutations of these three genes produced fewer pro-B cells than the singly heterozygous littermates. This study indicates that B-cell development is dependent not only on an essential function provided by the E2A gene but also on a combined dosage set by E2A, E2-2, and HEB.

Zhuang, Y; Cheng, P; Weintraub, H

1996-01-01

135

Cytoprotective effect of prostaglandin E2 in irradiated rat ileum  

SciTech Connect

Radiation injury to the gastrointestinal tract is an infrequent but major clinical problem. Results of previous studies have shown that prostaglandins provide cytoprotection of the gastrointestinal mucosa against a variety of noxious agents, although, prior to this study, the protection against radiation exposure had not been documented. Exteriorized segment of Sprague-Dawley rat ileum was radiated with 10 and 15 Gy (/sup 137/Cs). One group of rats was pretreated with prostaglandin E2 one hour before and 24 hours after radiation injury. The rats were sacrificed three and five days following radiation injury. Morphometric measurement of mucosal thickness, villous height, crypt of Lieberkuehn height and number of mitoses per square millimeter swath of tissue were analyzed. Also, /sup 125/IUdR and /sup 3/HTdR were injected in a group of rats radiated with 15 Gy (/sup 137/Cs). /sup 125/IUdR counts per minute per milligram of dry weight and /sup 3/HTdR labeled cells were counted and analyzed. The morphometric measurements and radioactive labeled tissue counts suggest that prostaglandin E2 has a cytoprotective effect upon irradiated rat ileum. Speculations about the possible mechanism and usefulness of this observation are included.

Tomas-de la Vega, J.E.; Banner, B.F.; Hubbard, M.; Boston, D.L.; Thomas, C.W.; Straus, A.K.; Roseman, D.L.

1984-01-01

136

An (e,2e) Spectrometer for Helium Autoionization Studies  

NASA Astrophysics Data System (ADS)

We are commissioning a new (e,2e) spectrometer which will be used to investigate the helium 2l2l' autoionizing region. The experimental technique to be used is similar to that of recent Cd experiments(N.L.S. Martin, D.B. Thompson, R.P. Bauman and M. Wilson, Phys. Rev. A 50), 3878 (1994). that measured pairs of (e,2e) energy spectra at ejected-electron directions 180^circ apart. At high incident electron energy the sum of these spectra is dominated by the dipole cross-section, while the difference isolates multipole interference cross-terms. A novel feature of the spectrometer is that in addition to an electron gun and scattered-electron detector, it has a pair of identical ejected-electron detectors located 180^circ apart on the same turntable; thus both spectra are taken simultaneously. The resistive anode of each of the two detectors is fed to a single position sensitive detection module; two non-overlapping images are formed which enables the separation of the spectra. Preliminary data will be presented.

Childers, J. G.; Martin, N. L. S.

1998-05-01

137

(e,2e) Studies of Xenon Autoionizing Levels  

NASA Astrophysics Data System (ADS)

We have begun a series of (e,2e) experiments on Xe in the autoionizing region between the ^2P_3/2 and ^2P_1/2 ionic limits. These are analogous to the series of experiments that were carried out on autoionizing levels in Cd.(N.L.S. Martin, R.P. Bauman, M. Wilson, Phys. Rev. A. 59), 2764 (1999). Xe is of particular interest because the scattering kinematics are similar to Cd: the energy loss of these autoionizing levels and hence the momentum transferred is the same in both atoms. However, the ejected electron energies are very different -- much less than 1 eV in Xe compared with approximately 4 eV in Cd. Our preliminary experiments suggest that at 150 eV incident energy the binary peak in Xe can be much smaller than the recoil peak. This is in sharp contrast to Cd where the binary peak was always greater than the recoil peak. We will present data analyzed in terms of the sum and difference of (e,2e) energy spectra measured at ejected-electron angles 180^circ apart.

Childers, J. G.; Martin, N. L. S.

2001-05-01

138

Cadmium (e,2e) Energy Spectra in the Autoionizing Region  

NASA Astrophysics Data System (ADS)

We will present an analysis of our comprehensive set of (e,2e) measurements in the Cd 4d^95s^25p autoionizing region, carried out for an incident electron-beam energy of 150 eV and scattering angles between 2^circ and 18^circ, corresponding to momentum transfer K=0.2 ? 1 au. The results are presented as the sum and difference of k_ej=±hat k pairs of (e,2e) ejected-electron energy spectra(N.L.S. Martin, D.B. Thompson, R.P. Bauman and M. Wilson, Phys.Rev.Lett 72), 2163 (1994); Phys. Rev. A 50, 3878 (1994). for three special directions hat k, and compared with plane wave Born calculations that include ejected-electron partial waves l=0?7. It is found that the relative Born phases are incorrect for l=0,1,2 by amounts that are independent of scattering angle. The relative Born magnitudes are extremely good for hat k=hat K, but are extremely bad for the other two hat k directions. With increasing scattering angle we observe a reduction in the ^3P_1/^1P1 intensity ratio in the sum spectra, probably due to an increase in exchange scattering, and we also see a previously unobserved Cd 4d^95s^25p J=3 autoionizing level.

Martin, N. L. S.; Bauman, R. P.; Wilson, M.

1997-04-01

139

The E2/M1 ratio in {Delta} photoproduction  

SciTech Connect

The properties of the transition from the nucleon to the {Delta}(1232) serve as a benchmark for models of nucleon structure. To first order, N {r_arrow} {Delta} photo-excitation is dominated by a simple M1 quark spin-flip transition. At higher order, small L = 2 components in the N and {Delta} wavefunctions allow this excitation to proceed via an electric quadrupole transition. Since Nucleon models differ greatly on the mechanisms used to generate these L = 2 components,, the ratio of E2/M1 transitions (EMR) provides a sensitive test for structure models. Here, new high-precision measurements of p({rvec {gamma}}, {pi}) and p({rvec {gamma}}, {gamma}) cross sections and beam asymmetries have been combined with other polarization ratios in a simultaneous analysis of both reactions. Compton scattering has provided two important new constraints on the photo-pion amplitude. The E2/M1 mixing ratio for the N {r_arrow} {Delta} transition extracted from this analysis is EMR = {minus}3.0% {+-} 0.3 (stat+sys) {+-} 0.2 (model).

Sandorfi, A.M. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.; Blanpied, G. [Univ. of South Carolina, Columbia, SC (United States). Dept. of Physics; Blecher, M. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Physics Dept.] [and others; LEGS Collaboration

1997-08-01

140

(e, 2e) Experiments on cadmium autoionizing levels  

SciTech Connect

We have extended our previous experimental investigations of coherent excitation, by electron impact, of Cd J = 0, 1, 2 autoionizing levels. The use of a position sensitive detector, in the ejected-electron channel, has led to higher count rates and a greatly improved energy resolution of 0.04 eV. The new data collection system permits the simultaneous acquisition of both ejected-electron and (e, 2e) energy spectra. The non-coincident spectra are used to normalize and align, with high accuracy, (e, 2e) spectra taken at ejected-electron angles 180{degrees} apart; the difference between these spectra then yields the interference spectrum. We will present new high resolution spectra for ejected- electron directions along the momentum-transfer axis; these show the (J = 1) x (J = 2) + (J = 1) x (J = 0) interference effects. We will also present spectra obtained for {open_quotes}magic angle{close_quotes} ejected-electron directions with respect to the momentum transfer axis; these experiments isolate the (J = 1) x (J = 0) interference.

Thompson, D.B.; Bauman, R.P.; Martin, N.L.S.

1993-05-01

141

The assessment of vitellogenin as a biomarker of exposure to estrogenic compounds in two Australian perciformes.  

PubMed

Vitellogenin (Vtg) is a yolk protein precursor that has been identified as a sensitive biomarker for exposure to estrogenic compounds. We evaluated specific monoclonal and polyclonal antibodies for reactivity with plasma Vtg from two Australian Perciformes, the tropical barramundi (Lates calcarifer) and the temperate black bream (Acanthopagrus butcheri). Blood plasma from 17beta-estradiol exposed (E2) male barramundi (20 mg kg(-1)) and male black bream (2.5-5.0 mg kg(-1)) were sent to Biosense Laboratories (Norway) for cross-reactivity testing using their extensive anti-Vtg antibody selection. Indirect ELISA results determined barramundi plasma displayed the highest binding affinities to ND-3G2 (monoclonal-Mab) and PO-1 (polyclonal-Pab). Black bream was most cross-reactive with ND-1C8 (Mab) and PO-2 (Pab). Next, plasma was assessed for Vtg induction in E2-dosed (5 mg kg(-1)), hatchery-reared barramundi and black bream versus a non-injected control group. Vtg production was assessed by Western blot and indirect ELISA using ND-3G2 and ND-1C8 Mabs, respectively. A prominent band was identified in the range of 100-200 kDa for all female black bream and for all E2-treated barramundi and black bream males, which was confirmed as Vtg by Western blot. Indirect ELISA results for barramundi demonstrated highly significant differences in E2-dosed fish as compared to control fish (Student t, P<0.001). E2 male black bream were significantly different than control males (Student t, P<0.001) and control and E2 females displayed highly significant differences (Student t, P<0.001). These results indicate that exposure to 17beta-estradiol induces significant Vtg production in males of the two Australian Perciformes, with potential use as a biomarker for exposure to estrogenic compounds. PMID:18377978

Codi King, Susan; Hassell, Kathryn; Nugegoda, Dayanthi; Kristiansen, Sven Inge

2008-02-26

142

Defective Gene Expression, S Phase Progression, and Maturation during Hematopoiesis in E2F1/E2F2 Mutant Mice  

PubMed Central

E2F plays critical roles in cell cycle progression by regulating the expression of genes involved in nucleotide synthesis, DNA replication, and cell cycle control. We show that the combined loss of E2F1 and E2F2 in mice leads to profound cell-autonomous defects in the hematopoietic development of multiple cell lineages. E2F2 mutant mice show erythroid maturation defects that are comparable with those observed in patients with megaloblastic anemia. Importantly, hematopoietic defects observed in E2F1/E2F2 double-knockout (DKO) mice appear to result from impeded S phase progression in hematopoietic progenitor cells. During DKO B-cell maturation, differentiation beyond the large pre-BII-cell stage is defective, presumably due to failed cell cycle exit, and the cells undergo apoptosis. However, apoptosis appears to be the consequence of failed maturation, not the cause. Despite the accumulation of hematopoietic progenitor cells in S phase, the combined loss of E2F1 and E2F2 results in significantly decreased expression and activities of several E2F target genes including cyclin A2. Our results indicate specific roles for E2F1 and E2F2 in the induction of E2F target genes, which contribute to efficient expansion and maturation of hematopoietic progenitor cells. Thus, E2F1 and E2F2 play essential and redundant roles in the proper coordination of cell cycle progression with differentiation which is necessary for efficient hematopoiesis.

Li, Feng X.; Zhu, Jing W.; Hogan, Christopher J.; DeGregori, James

2003-01-01

143

HIF proteins connect the RB-E2F factors to angiogenesis  

PubMed Central

Recently, we showed that E2F7 and E2F8 (E2F7/8) are critical regulators of angiogenesis through transcriptional control of VEGFA in cooperation with HIF.1 Here we investigate the existence of other novel putative angiogenic E2F7/8-HIF targets, and discuss the role of the RB-E2F pathway in regulating angiogenesis during embryonic and tumor development.

Bakker, Walbert. J.; Weijts, Bart G.M.W.; Westendorp, Bart; de Bruin, Alain

2013-01-01

144

Dynamical (e,2e) studies of tetrahydrofurfuryl alcohol  

NASA Astrophysics Data System (ADS)

Cross section data for electron scattering from DNA are important for modelling radiation damage in biological systems. Triply differential cross sections for the electron impact ionization of the highest occupied outer valence orbital of tetrahydrofurfuryl alcohol, which can be considered as an analogue to the deoxyribose backbone molecule in DNA, have been measured using the (e,2e) technique. The measurements have been performed with coplanar asymmetric kinematics at an incident electron energy of 250 eV, an ejected electron energy of 20 eV, and at scattered electron angles of -5°, -10°, and -15°. Experimental results are compared with corresponding theoretical calculations performed using the molecular 3-body distorted wave model. Some important differences are observed between the experiment and calculations.

Bellm, S. M.; Builth-Williams, J. D.; Jones, D. B.; Chaluvadi, Hari; Madison, D. H.; Ning, C. G.; Wang, F.; Ma, X. G.; Lohmann, B.; Brunger, M. J.

2012-06-01

145

Three body effects in low energy (e,2e) processes  

NASA Astrophysics Data System (ADS)

Within the last two years a number of highly refined measurements have been performed on H targets which have yielded accurate absolute data for a range of energies and geometries [1] and it would appear that the experimental situation for this, the simplest of atomic targets is now resolved. The theoretical situation is however far from satisfactory and in this paper we will analysis some of the main approaches and characterize their strengths and their weaknesses. We have developed a numerical method which allows us to evaluate triple differential cross sections (TDCS) using the most complex position dependent analytic ansatz wave function and we will present results, using this for low energy (e,2e) processes. We will see that this approach fails when incident channel effects, such as target polarization are likely to be strong.

Rasch, J.; Whelan, Colm T.

1999-06-01

146

Dynamical (e,2e) studies of tetrahydrofurfuryl alcohol.  

PubMed

Cross section data for electron scattering from DNA are important for modelling radiation damage in biological systems. Triply differential cross sections for the electron impact ionization of the highest occupied outer valence orbital of tetrahydrofurfuryl alcohol, which can be considered as an analogue to the deoxyribose backbone molecule in DNA, have been measured using the (e,2e) technique. The measurements have been performed with coplanar asymmetric kinematics at an incident electron energy of 250 eV, an ejected electron energy of 20 eV, and at scattered electron angles of -5°, -10°, and -15°. Experimental results are compared with corresponding theoretical calculations performed using the molecular 3-body distorted wave model. Some important differences are observed between the experiment and calculations. PMID:22755568

Bellm, S M; Builth-Williams, J D; Jones, D B; Chaluvadi, Hari; Madison, D H; Ning, C G; Wang, F; Ma, X G; Lohmann, B; Brunger, M J

2012-06-28

147

NRIP, a novel calmodulin binding protein, activates calcineurin to dephosphorylate human papillomavirus E2 protein.  

PubMed

Previously, we found a gene named nuclear receptor interaction protein (NRIP) (or DCAF6 or IQWD1). We demonstrate that NRIP is a novel binding protein for human papillomavirus 16 (HPV-16) E2 protein. HPV-16 E2 and NRIP can directly associate into a complex in vivo and in vitro, and the N-terminal domain of NRIP interacts with the transactivation domain of HPV-16 E2. Only full-length NRIP can stabilize E2 protein and induce HPV gene expression, and NRIP silenced by two designed small interfering RNAs (siRNAs) decreases E2 protein levels and E2-driven gene expression. We found that NRIP can directly bind with calmodulin in the presence of calcium through its IQ domain, resulting in decreased E2 ubiquitination and increased E2 protein stability. Complex formation between NRIP and calcium/calmodulin activates the phosphatase calcineurin to dephosphorylate E2 and increase E2 protein stability. We present evidences for E2 phosphorylation in vivo and show that NRIP acts as a scaffold to recruit E2 and calcium/calmodulin to prevent polyubiquitination and degradation of E2, enhancing E2 stability and E2-driven gene expression. PMID:21543494

Chang, Szu-Wei; Tsao, Yeou-Ping; Lin, Chia-Yi; Chen, Show-Li

2011-05-04

148

Two E2F Elements Regulate the Proliferating Cell Nuclear Antigen Promoter Differently during Leaf Development  

PubMed Central

E2F transcription factors regulate genes expressed at the G1/S boundary of the cell division cycle in higher eukaryotes. Although animal E2F proteins and their target promoters have been studied extensively, little is known about how these factors regulate plant promoters. An earlier study identified two E2F consensus binding sites in the promoter of a Nicotiana benthamiana gene encoding proliferating cell nuclear antigen (PCNA) and showed that the proximal element (E2F2) is required for the full repression of PCNA expression in mature leaves. In this study, we examined the distal element (E2F1) and how it interacts with the E2F2 site to regulate the PCNA promoter. Gel shift assays using plant nuclear extracts or purified Arabidopsis E2F and DP proteins showed that different complexes bind to the two E2F sites. Mutation of the E2F1 site or both sites differentially altered PCNA promoter function in transgenic plants. As reported previously for the E2F2 mutation, the E2F1 and E2F1+2 mutations partially relieved the repression of the PCNA promoter in mature leaves. In young tissues, the E2F1 mutation resulted in a threefold reduction in PCNA promoter activity, whereas the E2F1+2 mutation had no detectable effect. The activity of E2F1+2 mutants was indistinguishable from that of E2F2 mutants. These results demonstrate that both E2F elements contribute to the repression of the PCNA promoter in mature leaves, whereas the E2F1 site counters the repression activity of the E2F2 element in young leaves.

Egelkrout, Erin M.; Mariconti, Luisa; Settlage, Sharon B.; Cella, Rino; Robertson, Dominique; Hanley-Bowdoin, Linda

2002-01-01

149

Two E2F elements regulate the proliferating cell nuclear antigen promoter differently during leaf development.  

PubMed

E2F transcription factors regulate genes expressed at the G1/S boundary of the cell division cycle in higher eukaryotes. Although animal E2F proteins and their target promoters have been studied extensively, little is known about how these factors regulate plant promoters. An earlier study identified two E2F consensus binding sites in the promoter of a Nicotiana benthamiana gene encoding proliferating cell nuclear antigen (PCNA) and showed that the proximal element (E2F2) is required for the full repression of PCNA expression in mature leaves. In this study, we examined the distal element (E2F1) and how it interacts with the E2F2 site to regulate the PCNA promoter. Gel shift assays using plant nuclear extracts or purified Arabidopsis E2F and DP proteins showed that different complexes bind to the two E2F sites. Mutation of the E2F1 site or both sites differentially altered PCNA promoter function in transgenic plants. As reported previously for the E2F2 mutation, the E2F1 and E2F1+2 mutations partially relieved the repression of the PCNA promoter in mature leaves. In young tissues, the E2F1 mutation resulted in a threefold reduction in PCNA promoter activity, whereas the E2F1+2 mutation had no detectable effect. The activity of E2F1+2 mutants was indistinguishable from that of E2F2 mutants. These results demonstrate that both E2F elements contribute to the repression of the PCNA promoter in mature leaves, whereas the E2F1 site counters the repression activity of the E2F2 element in young leaves. PMID:12468739

Egelkrout, Erin M; Mariconti, Luisa; Settlage, Sharon B; Cella, Rino; Robertson, Dominique; Hanley-Bowdoin, Linda

2002-12-01

150

High incidence of T-cell tumors in E2A-null mice and E2A/Id1 double-knockout mice.  

PubMed Central

The basic-helix-loop-helix (bHLH) proteins encoded by the E2A gene are broadly expressed transcription regulators which function through binding to the E-box enhancer sequences. The DNA binding activities of E2A proteins are directly inhibited upon dimerization with the Id1 gene product. It has been shown that disruption of the E2A gene leads to a complete block in B-lymphocyte development and a high frequency of neonatal death. We report here that nearly half of the surviving E2A-null mice develop acute T-cell lymphoma between 3 to 10 months of age. We further show that disruption of the Id1 gene improves the chance of postnatal survival of E2A-null mice, indicating that Id1 is a canonical negative regulator of E2A and that the unbalanced ratio of E2A to Id1 may contribute to the postnatal death of the E2A-null mice. However, the E2A/Id1 double-knockout mice still develop T-cell tumors once they reach the age of 3 months. This result suggests that E2A may be essential for maintaining the homeostasis of T lymphocytes during their constant renewal in adult life.

Yan, W; Young, A Z; Soares, V C; Kelley, R; Benezra, R; Zhuang, Y

1997-01-01

151

RBF binding to both canonical E2F targets and noncanonical targets depends on functional dE2F/dDP complexes.  

PubMed

The retinoblastoma (RB) family of proteins regulate transcription. These proteins lack intrinsic DNA-binding activity but are recruited to specific genomic locations through interactions with sequence-specific DNA-binding factors. The best-known target of RB protein (pRB) is the E2F transcription factor; however, many other chromatin-associated proteins have been described that may allow RB family members to act at additional sites. To gain a perspective on the scale of E2F-dependent and E2F-independent functions, we generated genome-wide binding profiles of RBF1 and dE2F proteins in Drosophila larvae. RBF1 and dE2F2 associate with a large number of binding sites at genes with diverse biological functions. In contrast, dE2F1 was detected at a smaller set of promoters, suggesting that it overrides repression by RBF1/dE2F2 at a specific subset of targets. Approximately 15% of RBF1-bound regions lacked consensus E2F-binding motifs. To test whether RBF1 action at these sites is E2F independent, we examined dDP mutant larvae that lack any functional dE2F/dDP heterodimers. As measured by chromatin immunoprecipitation-microarray analysis (ChIP-chip), ChIP-quantitative PCR (qPCR), and cell fractionation, the stable association of RBF1 with chromatin was eliminated in dDP mutants. This requirement for dDP was seen at classic E2F-regulated promoters and at promoters that lacked canonical E2F-binding sites. These results suggest that E2F/DP complexes are essential for all genomic targeting of RBF1. PMID:22927638

Korenjak, Michael; Anderssen, Endre; Ramaswamy, Sridhar; Whetstine, Johnathan R; Dyson, Nicholas J

2012-08-27

152

RBF Binding to both Canonical E2F Targets and Noncanonical Targets Depends on Functional dE2F/dDP Complexes  

PubMed Central

The retinoblastoma (RB) family of proteins regulate transcription. These proteins lack intrinsic DNA-binding activity but are recruited to specific genomic locations through interactions with sequence-specific DNA-binding factors. The best-known target of RB protein (pRB) is the E2F transcription factor; however, many other chromatin-associated proteins have been described that may allow RB family members to act at additional sites. To gain a perspective on the scale of E2F-dependent and E2F-independent functions, we generated genome-wide binding profiles of RBF1 and dE2F proteins in Drosophila larvae. RBF1 and dE2F2 associate with a large number of binding sites at genes with diverse biological functions. In contrast, dE2F1 was detected at a smaller set of promoters, suggesting that it overrides repression by RBF1/dE2F2 at a specific subset of targets. Approximately 15% of RBF1-bound regions lacked consensus E2F-binding motifs. To test whether RBF1 action at these sites is E2F independent, we examined dDP mutant larvae that lack any functional dE2F/dDP heterodimers. As measured by chromatin immunoprecipitation-microarray analysis (ChIP-chip), ChIP-quantitative PCR (qPCR), and cell fractionation, the stable association of RBF1 with chromatin was eliminated in dDP mutants. This requirement for dDP was seen at classic E2F-regulated promoters and at promoters that lacked canonical E2F-binding sites. These results suggest that E2F/DP complexes are essential for all genomic targeting of RBF1.

Korenjak, Michael; Anderssen, Endre; Ramaswamy, Sridhar; Whetstine, Johnathan R.

2012-01-01

153

Developing a Biosensor for Estrogens in Water Samples: Study ofthe Real-time Response of Live Cells of the Estrogen-sensitive YeastStrain RMY/ER-ERE using Fluorescence Microscopy  

SciTech Connect

Using a fluorescein di-{beta}-D-galactopyranoside (FDG) substrate we show that in live cells of an estrogen-sensitive yeast strain RMY/ER-ERE with human estrogen receptor (ER{alpha}) gene and the lacZ gene which encodes {beta}-galactosidase, the uptake of 17 {beta}-estradiol (E2) and the subsequent production of {beta}-galactosidase enzyme occur quite rapidly, with maximal enzyme-catalyzed product formation evident after about 30 minutes of exposure to E2. This finding which agrees with the well-known rates of enzyme-catalyzed reactions could have implications for shortening the duration of environmental sample screening and monitoring regimes using yeast-based estrogen assays, and the development of biosensors for environmental estrogens to complement quantification methods.

Wozei, E.; Hermanowicz, S.W.; Holman, H-Y.N.

2005-07-13

154

Developing a Biosensor for Estrogens in Water Samples: Study ofthe Real-time Response of Live Cells of the Estrogen-sensitive YeastStrain RMY/ER-ERE using Fluorescence Microscopy  

SciTech Connect

Using a fluorescein di-{beta}-d-galactopyranoside (FDG) substrate we show that in live cells of an estrogen-sensitive yeast strain RMY/ER-ERE with human estrogen receptor (ER{alpha}) gene and the lacZ gene which encodes {beta}-galactosidase, the uptake of 17{beta}-estradiol (E2) and the subsequent production of {beta}-galactosidase enzyme occur quite rapidly, with maximal enzyme-catalyzed product formation evident after about 30 min of exposure to E2. This finding which agrees with the well-known rates of enzyme-catalyzed reactions could have implications for shortening the duration of environmental sample screening and monitoring regimes using yeast-based estrogen assays, and the development of biosensors for environmental estrogens to complement quantification methods.

Wozei, E.; Hermanowicz, S.W.; Holman, H-Y.N.

2006-01-01

155

VIP1, an Arabidopsis protein that interacts with Agrobacterium VirE2, is involved in VirE2 nuclear import and Agrobacterium infectivity.  

PubMed

T-DNA nuclear import is a central event in genetic transformation of plant cells by Agrobacterium. This event is thought to be mediated by two bacterial proteins, VirD2 and VirE2, which are associated with the transported T-DNA molecule. While VirD2 is imported into the nuclei of plant, animal and yeast cells, nuclear uptake of VirE2 occurs most efficiently in plant cells. To understand better the mechanism of VirE2 action, a cellular interactor of VirE2 was identified and its encoding gene cloned from Arabidopsis. The identified plant protein, designated VIP1, specifically bound VirE2 and allowed its nuclear import in non-plant systems. In plants, VIP1 was required for VirE2 nuclear import and Agrobacterium tumorigenicity, participating in early stages of T-DNA expression. PMID:11432846

Tzfira, T; Vaidya, M; Citovsky, V

2001-07-01

156

Disruption of plE2 , the gene for the E2 subunit of the plastid pyruvate dehydrogenase complex, in Arabidopsis causes an early embryo lethal phenotype  

Microsoft Academic Search

The pyruvate dehydrogenase multi-enzyme complex is the main source of acetyl-CoA formation in the plastids of plants and is composed of multiple copies of four different subunits, E1a, E1ß, E2, and E3. A T-DNA insertion into the gene for the plastidic E2 (dihydrolipoyl acetyltransferase) subunit, plE2, of the complex in Arabidopsis destroys the expression of that gene. The resulting mutation

Ming Lin; Robert Behal; David J. Oliver

2003-01-01

157

Ras stimulation of E2F activity and a consequent E2F regulation of integrin alpha6beta4 promote the invasion of breast carcinoma cells.  

PubMed

Active Ras proteins contribute to breast carcinogenesis and progression. Here, we provide evidence that active H-Ras regulates the expression and activity of the E2F family of transcription factors in SUM-159 breast carcinoma cells. In addition, we show by using a DNA-binding mutant of E2F, as well as expression of specific E2Fs that are transcriptionally active, that the active E2Fs1-3 can mediate the H-Ras-dependent invasion of SUM-159 cells. The inhibitory E2Fs4-5, in contrast, do not influence invasion. One mechanism by which the active E2Fs promote H-Ras-dependent invasion seems to be their ability to increase expression of the beta4 integrin subunit, a component of the alpha6beta4 integrin that is known to enhance carcinoma invasion. Specifically, expression of E2Fs1-3 increased beta4 mRNA, protein, and cell surface expression. The active E2Fs were unable to stimulate invasion in cells that expressed a beta4 short hairpin RNA. This effect of the active E2Fs on beta4 expression does not seem to result from E2F-mediated beta4 transcription because the beta4 promoter lacks known E2F binding motifs. In summary, the data reported here indicate a novel mechanism by which H-Ras can promote the invasion of breast carcinoma cells. This mechanism links active H-Ras, transcriptionally active E2F, and the alpha6beta4 integrin in a common pathway that culminates in enhanced alpha6beta4-dependent invasion. PMID:16778205

Yoon, Sang-Oh; Shin, Sejeong; Mercurio, Arthur M

2006-06-15

158

Model for Evaluating Steroids Acting at the Hypothalamus-Pituitary Axis Using Radioimmunoassay and Related Procedures.  

National Technical Information Service (NTIS)

Relative affinity constants for binding of estrone (E sub 1 ), estriol (E sub 3 ), 17 beta -estradiol (E sub 2 ) and 17 alpha -ethinyl-17 beta -estradiol (EE sub 2 ) to cytosol estrogen-receptor of rat hypothalamus and pituitary were estimated by radiolig...

J. Spona C. Bieglmayer R. Schroeder E. Poeckl

1977-01-01

159

Prostaglandin E2 and the Pathogenesis of Pulmonary Fibrosis  

PubMed Central

Prostaglandin (PG)E2 is a bioactive eicosanoid that regulates many biologically important processes in part due to its ability to signal through four distinct G-protein–coupled receptors with differential signaling activity and unique expression patterns in different cell types. Although PGE2 has been linked to malignancy in many organs, it is believed to play a beneficial role in the setting of fibrotic lung disease. This is in part due to the ability of PGE2 to limit many of the pathobiologic features of lung fibroblasts and myofibroblasts, including the ability of PGE2 to limit fibroblast proliferation, migration, collagen secretion, and, as originally reported in the Journal by us in 2003, the ability to limit transforming growth factor (TGF)-?–induced myofibroblast differentiation. In the setting of lung fibrosis, PGE2 production and signaling is often diminished. In the last 8 years, significant advances have been made to better understand the dysregulation of PGE2 production and signaling in the setting of lung fibrosis. We also have a clearer picture of how PGE2 inhibits myofibroblast differentiation and the receptor signaling pathways that can influence fibroblast proliferation. This review highlights these recent advances and offers new insights into the potential ways that PGE2 and its downstream signals can be regulated for therapeutic benefit in a disease that has no validated treatment options.

Bozyk, Paul D.

2011-01-01

160

Prostanoid signaling: dual role for prostaglandin E2 in neurotoxicity  

PubMed Central

The prostanoids, a naturally occurring subclass of eicosanoids, are lipid mediators generated through oxidative pathways from arachidonic acid. These cyclooxygenase metabolites, consisting of the prostaglandins (PG), prostacyclin and tromboxane, are released in response to a variety of physiological and pathological stimuli in almost all organs, including the brain. They are produced by various cell types and act upon targeted cells via specific G protein-coupled receptors. The existence of multiple receptors, cross-reactivity and coupling to different signal transduction pathways for each prostanoid, collectively establish their diverse effects. Notably, these effects can occur in functionally opposing directions within the same cell or organ. Prostaglandin E2 (PGE2) is the most versatile prostanoid because of its receptors, E Prostanoid (EP) receptor subtypes 1 through 4, its biological heterogeneity and its differential expression on neuronal and glial cells throughout the central nervous system. Since PGE2 plays an important role in processes associated with various neurological diseases, this review focuses on its dual neuroprotective and neurotoxic role in EP receptor subtype signaling pathways in different models of brain injury.

Milatovic, Dejan; Montine, Thomas J.; Aschner, Michael

2011-01-01

161

Differential Stem and Progenitor Cell Trafficking by Prostaglandin E2  

PubMed Central

SUMMARY To maintain lifelong production of blood cells, hematopoietic stem cells (HSC) are tightly regulated by inherent programs and extrinsic regulatory signals received from their microenvironmental niche. Long-term repopulating HSC (LT-HSC) reside in several, perhaps overlapping, niches that produce regulatory molecules/signals necessary for homeostasis and increased output following stress/injury 1–5. Despite significant advances in specific cellular or molecular mechanisms governing HSC/niche interactions, little is understood about regulatory function within the intact mammalian hematopoietic niche. Recently, we and others described a positive regulatory role for Prostaglandin E2 (PGE2) on HSC function ex vivo 6,7. While exploring the role of endogenous PGE2 we unexpectedly observed hematopoietic egress after nonsteroidal anti-inflammatory drug (NSAID) treatment. Surprisingly, this was independent of the SDF-1/CXCR4 axis. Stem and progenitor cells were found to have differing mechanisms of egress, with HSC transit to the periphery dependent on niche attenuation and reduction in the retentive molecule osteopontin (OPN). Hematopoietic grafts mobilized with NSAIDs had superior repopulating ability and long-term engraftment. Treatment of non-human primates and healthy human volunteers confirmed NSAID-mediated egress in higher species. PGE2 receptor knockout mice demonstrated that progenitor expansion and stem/progenitor egress resulted from reduced EP4 receptor signaling. These results not only uncover unique regulatory roles for EP4 signaling in HSC retention in the niche but also define a rapidly translatable strategy to therapeutically enhance transplantation.

Hoggatt, Jonathan; Mohammad, Khalid S.; Singh, Pratibha; Hoggatt, Amber F.; Chitteti, Brahmananda Reddy; Speth, Jennifer M.; Hu, Peirong; Poteat, Bradley A.; Stilger, Kayla N.; Ferraro, Francesca; Silberstein, Lev; Wong, Frankie K.; Farag, Sherif S.; Czader, Magdalena; Milne, Ginger L.; Breyer, Richard M.; Serezani, Carlos H.; Scadden, David T.; Guise, Theresa; Srour, Edward F.; Pelus, Louis M.

2013-01-01

162

Inhalation treatment of pulmonary fibrosis by liposomal prostaglandin E2.  

PubMed

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and often fatal form of interstitial lung disease. We hypothesized that the local pulmonary delivery of prostaglandin E2 (PGE2) by liposomes can be used for the effective treatment of IPF. To test this hypothesis, we used a murine model of bleomycin-induced IPF to evaluate liposomal delivery of PGE2 topically to the lungs. Animal survival, body weight, hydroxyproline content in the lungs, lung histology, mRNA, and protein expression were studied. After inhalation delivery, liposomes accumulated predominately in the lungs. In contrast, intravenous administration led to the accumulation of liposomes mainly in kidney, liver, and spleen. Liposomal PGE2 prevented the disturbances in the expression of many genes associated with the development of IPF, substantially restricted inflammation and fibrotic injury in the lung tissues, prevented decrease in body weight, limited hydroxyproline accumulation in the lungs, and virtually eliminated mortality of animals after intratracheal instillation of bleomycin. In summary, our data provide evidence that pulmonary fibrosis can be effectively treated by the inhalation administration of liposomal form of PGE2 into the lungs. The results of the present investigations make the liposomal form of PGE2 an attractive drug for the effective inhalation treatment of idiopathic pulmonary fibrosis. PMID:23228437

Ivanova, Vera; Garbuzenko, Olga B; Reuhl, Kenneth R; Reimer, David C; Pozharov, Vitaly P; Minko, Tamara

2012-12-08

163

(e,2e) ionization studies of diatomic & triatomic molecules  

NASA Astrophysics Data System (ADS)

(e,2e) studies yield the most detailed experimental data on electron impact ionization of atomic & molecular targets for comparison to quantum collision theories. Coincidence techniques are here used to measure the probability of ionization as a function of the incident electron scattering angle and angle of the electron ejected from the target. In Manchester we study this process at low energies, where the ionization probability is greatest & the interaction most complex. We recently considered ionization of simple molecules (eg H2 & H2O) from a coplanar geometry to the perpendicular plane[1-4], and have discovered the interaction is far more complex than for ionization of atoms [5]. We here present comparisons between theory & experiment, and discuss new methods we intend to implement to study ionization from laser-aligned atoms & molecules. References. [1] J Colgan et al Phys Rev Lett 101 233201 (2008) [2] O Al-Hagan et al Nature Physics 5 59 (2009) [3] J Colgan et al Phys Rev A 79 052704 (2009) [4] C Kaiser et al J Phys B 40 2563 (2007) [5] A J Murray et al J Phys B 36 4875 (2003) & references therein

Nixon, Kate; Murray, Andrew; Kaiser, Christian; Al-Hagan, Ola; Colgan, James; Madison, Don

2009-10-01

164

Resetting of peripheral circadian clock by prostaglandin E2.  

PubMed

In mammals, the master circadian pacemaker is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is thought to drive peripheral oscillators by controlling neuronal and humoral signals that can entrain the peripheral clocks. Here, we show that prostaglandin E2 (PGE2), a proinflammatory compound known to have diverse biological effects, is able to act as an in vivo clock-resetting agent. We find that in cultured NIH3T3 fibroblasts, PGE2 is able to induce transient expression of Period 1 messenger RNA and the following circadian oscillation of clock gene expression. Furthermore, we demonstrate that intraperitoneal administration of PGE2 results in the phase shift of circadian gene expression in mouse peripheral tissues in a time-dependent manner. This phase shift is also induced by the EP1/EP3 agonist sulprostone but not by the EP2 agonist butaprost. The PGE2-induced phase shift is inhibited by the EP1 antagonist SC-51322. These results suggest that PGE2 acts as an in vivo clock-resetting factor by means of the EP1 subtype of PGE receptors. PMID:15723041

Tsuchiya, Yoshiki; Minami, Itsunari; Kadotani, Hiroshi; Nishida, Eisuke

2005-03-01

165

(e,2e) Angular Distributions and Energy Spectra in Cadmium  

NASA Astrophysics Data System (ADS)

Early angular distribution measurements on the Cd 4d^95s^25p ^3P1 autoionizing level( N.L.S. Martin and K.J. Ross, J. Phys. B 17), 4033 (1984). did not correspond with those expected from a single level of mixed ^3P+^1P character. An analysis indicated that the results were consistent with the combined angular distributions of the ^3P1 level and a previously unknown ^1D2 even parity autoionizing level at a slightly displaced ejected-electron energy. Recent (e,2e) energy spectra measurements( N.L.S. Martin, D.B. Thompson, R.P. Bauman, M. Wilson, Phys.Rev.A 50), 3878 (1994). that spanned the 4d^95s^25p energy region were interpreted with the help of ab initio structure and plane wave Born amplitude calculations. It was found that the experimental data could be modeled satisfactorily without including a ^1D2 level close to the ^3P1 level. We will present new calculations which reconcile these apparent contradictions between the angular distributions and energy spectra.

Martin, N. L. S.; Bauman, R. P.; Ross, K. J.; Wilson, M.

1996-05-01

166

(e,2e) angular distributions and energy spectra in cadmium  

SciTech Connect

Early angular distribution measurements on the Cd 4d{sup 9}5s{sup 2}5p {sup 3}P{sub 1} autoionizing level did not correspond with those expected from a single level of mixed {sup 3}P+{sup 1}P character. An analysis indicated that the results were consistent with the combined angular distributions of the {sup 3}P{sub 1} level and a previously unknown {sup 1}D{sub 2} even parity autoionizing level at a slightly displaced ejected-electron energy. Recent (e,2e) energy spectra measurements that spanned the 4d{sup 9}5s{sup 2}5p energy region were interpreted with the help of ab-initio structure and plane wave Born amplitude calculations. It was found that the experimental data could be modeled satisfactorily without including a {sup 1}D{sub 2} level close to the {sup 3}P{sub 1} level. The authors will present new calculations which reconcile these apparent contradictions between the angular distributions and energy spectra.

Martin, N.L.S.; Bauman, R.P.; Ross, K.J. [Univ. of Southampton (United Kingdom); Wilson, M. [Univ. of London (United Kingdom)

1996-05-01

167

The doubling of von Klitzing's constant h/e^2  

NASA Astrophysics Data System (ADS)

The Hall resistivity is found to become a function of spin. For positive spin, one value is found but for negative sign in the spin, another value occurs. In this way, there is never only one value of the resistivity but there is doubling of values. The value of the von Klitzing's constant is a special case of more general dependence of resistivity on the spin. We investigate the effect of Landau levels. For extreme quantum limit, n=0, the effective charge of the electron becomes (1/2)ge. The fractional charge arises for finite value of the angular momentum. The fractional as well as the integral values of the charge are in full agreement with the experimental data. The generalized constant is h/[(1/2)ge]e which under special conditions becomes h/e2 which is the von Klitzing's constant [1]. [1] K. N. Shrivastava, Phys. Lett. A 113,435(1986); A326,469(2004); Mod. Phys. Lett. 13,1087(1999); 14,1009(2000); AIP Conf. Proc. 909, 43-49(2007); 909.50-56(2007);1017, 422-428(2008);1017,326-330(2008); 1017, 47-56(2008), Proc. SPIE(USA)7155,71552F1-8[7155&_slash;86](2008).

Shrivastava, Keshav

2009-03-01

168

Improving radiation tolerance in e2v CCD sensors  

NASA Astrophysics Data System (ADS)

e2v have been developing new approaches to mitigate against the effects of radiation damage in CCD sensors. The first of these is our "rad-hard" device technology, primarily developed to reduce the flat-band voltage shift following ionising radiation. With this a very significant improvement has been demonstrated, the flat-band shift reducing from typically 100-200 mV/kRad(Si) with standard devices to only 6 mV/kRad(Si), plus an associated reduction in the increase in surface dark signal. The rad-hard process thereby allows devices to be operated in environments with up to at least 500kRad total dose and/or with reduced shielding. Developments aimed at reducing the impact of proton radiation have included the manufacture of p-channel devices. Our initial data indicates that at -50°C the increase in charge transfer inefficiency is reduced by a factor of two times for parallel transfer and five times for serial transfer.

Burt, D.; Endicott, J.; Jerram, P.; Pool, P.; Morris, D.; Hussain, A.; Ezra, P.

2009-08-01

169

Regulation of E2F1 by BRCT Domain-Containing Protein TopBP1  

PubMed Central

The E2F transcription factor integrates cellular signals and coordinates cell cycle progression. Our prior studies demonstrated selective induction and stabilization of E2F1 through ATM-dependent phosphorylation in response to DNA damage. Here we report that DNA topoisomerase II? binding protein 1 (TopBP1) regulates E2F1 during DNA damage. TopBP1 contains eight BRCT (BRCA1 carboxyl-terminal) motifs and upon DNA damage is recruited to stalled replication forks, where it participates in a DNA damage checkpoint. Here we demonstrated an interaction between TopBP1 and E2F1. The interaction depended on the amino terminus of E2F1 and the sixth BRCT domain of TopBP1. It was specific to E2F1 and was not observed in E2F2, E2F3, or E2F4. This interaction was induced by DNA damage and phosphorylation of E2F1 by ATM. Through this interaction, TopBP1 repressed multiple activities of E2F1, including transcriptional activity, induction of S-phase entry, and apoptosis. Furthermore, TopBP1 relocalized E2F1 from diffuse nuclear distribution to discrete punctate nuclear foci, where E2F1 colocalized with TopBP1 and BRCA1. Thus, the specific interaction between TopBP1 and E2F1 during DNA damage inhibits the known E2F1 activities but recruits E2F1 to a BRCA1-containing repair complex, suggesting a direct role of E2F1 in DNA damage checkpoint/repair at stalled replication forks.

Liu, Kang; Lin, Fang-Tsyr; Ruppert, J. Michael; Lin, Weei-Chin

2003-01-01

170

Differential expression of members of the E2F family of transcription factors in rodent testes  

PubMed Central

Background The E2F family of transcription factors is required for the activation or repression of differentially expressed gene programs during the cell cycle in normal and abnormal development of tissues. We previously determined that members of the retinoblastoma protein family that interacts with the E2F family are differentially expressed and localized in almost all the different cell types and tissues of the testis and in response to known endocrine disruptors. In this study, the cell-specific and stage-specific expression of members of the E2F proteins has been elucidated. Methods We used immunohistochemical (IHC) analysis of tissue sections and Western blot analysis of proteins, from whole testis and microdissected stages of seminiferous tubules to study the differential expression of the E2F proteins. Results For most of the five E2F family members studied, the localizations appear conserved in the two most commonly studied rodent models, mice and rats, with some notable differences. Comparisons between wild type and E2F-1 knockout mice revealed that the level of E2F-1 protein is stage-specific and most abundant in leptotene to early pachytene spermatocytes of stages IX to XI of mouse while strong staining of E2F-1 in some cells close to the basal lamina of rat tubules suggest that it may also be expressed in undifferentiated spermatogonia. The age-dependent development of a Sertoli-cell-only phenotype in seminiferous tubules of E2F-1 knockout males corroborates this, and indicates that E2F-1 is required for spermatogonial stem cell renewal. Interestingly, E2F-3 appears in both terminally differentiated Sertoli cells, as well as spermatogonial cells in the differentiative pathway, while the remaining member of the activating E2Fs, E2F-2 is most concentrated in spermatocytes of mid to late prophase of meiosis. Comparisons between wildtype and E2F-4 knockout mice demonstrated that the level of E2F-4 protein displays a distinct profile of stage-specificity compared to E2F-1, which is probably related to its prevalence and role in Sertoli cells. IHC of rat testis indicates that localization of E2F-5 is distinct from that of E2F-4 and overlaps those of E2F-1 and E2F-2. Conclusion The E2F-1 represents the subfamily of transcription factors required during stages of DNA replication and gene expression for development of germ cells and the E2F-4 represents the subfamily of transcription factors that help maintain gene expression for a terminally differentiated state within the testis.

El-Darwish, Kame S; Parvinen, Martti; Toppari, Jorma

2006-01-01

171

Hydrogen sulfide inhibits preoptic prostaglandin E2 production during endotoxemia.  

PubMed

Hydrogen sulfide (H(2)S) is a gaseous neuromodulator endogenously produced in the brain by the enzyme cystathionine ?-synthase (CBS). We tested the hypothesis that H(2)S acts within the anteroventral preoptic region of the hypothalamus (AVPO) modulating the production of prostaglandin (PG) E(2) (the proximal mediator of fever) and cyclic AMP (cAMP). To this end, we recorded deep body temperature (Tb) of rats before and after pharmacological modulation of the CBS-H(2)S system combined or not with lipopolysaccharide (LPS) exposure, and measured the levels of H(2)S, cAMP, and PGE(2) in the AVPO during systemic inflammation. Intracerebroventricular (icv) microinjection of aminooxyacetate (AOA, a CBS inhibitor; 100 pmol) did not affect basal PGE(2) production and Tb, but enhanced LPS-induced PGE(2) production and fever, indicating that endogenous H(2)S plays an antipyretic role. In agreement, icv microinjection of a H(2)S donor (Na(2)S; 260 nmol) reduced the LPS-induced PGE(2) production and fever. Interestingly, we observed that the AVPO levels of H(2)S were decreased following the immunoinflammatory challenge. Furthermore, fever was associated with decreased levels of AVPO cAMP and increased levels of AVPO PGE(2). The LPS-induced decreased levels of cAMP were reduced to a lesser extent by the H(2)S donor. The LPS-induced PGE(2) production was potentiated by AOA (the CBS inhibitor) and inhibited by the H(2)S donor. Our data are consistent with the notion that the gaseous messenger H(2)S synthesis is downregulated during endotoxemia favoring PGE(2) synthesis and lowering cAMP levels in the preoptic hypothalamus. PMID:23153577

Kwiatkoski, Marcelo; Soriano, Renato N; Araujo, Rebeca M; Azevedo, Leopoldo U; Batalhao, Marcelo E; Francescato, Heloísa D C; Coimbra, Terezila M; Carnio, Evelin C; Branco, Luiz G S

2012-11-12

172

Laser-assisted (e,2e) collisions in helium  

SciTech Connect

We have studied the influence of a strong laser on the dynamics of fast (e,2e) collisions in helium, in asymmetric, coplanar geometry. The interaction of the laser field with the unbound electrons is treated in a nonperturbative way. The wave functions of the incident and scattered electrons in the laser field are treated as Volkov waves, while that of the ejected electron moving in the combined field of the residual He{sup +} ion and of the laser is obtained by generalizing the ansatz proposed by Joachain {ital et al.} [Phys. Rev. Lett. {bold 61}, 165 (1988)] for the case of atomic hydrogen. On the other hand, the interaction of bound electrons with the laser field is treated by using first-order perturbation theory, assuming that the electric-field strength is much less than the atomic unit e/a{sub 0}{sup 2}{approx_equal}5{times}10{sup 9} Vcm{sup {minus}1}. The required scattering amplitudes are evaluated by using two different implementations of the Dalgarno and Lewis method. The first approach uses a technique proposed by Zernik and Klopfenstein, based on Laplace transforms and analytic continuation procedures. The second approach is based on a Sturmian basis expansion. The influence of the laser parameters (photon energy and intensity and direction of polarization) on the angular distribution of the ejected electron is analyzed, and several illustrative examples are discussed. We find that in general the triple-differential cross sections are strongly dependent on the dressing of the projectile and the target by the laser field. {copyright} {ital 1997} {ital The American Physical Society}

Khalil, D.; Maquet, A.; Taieeb, R. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Joachain, C.J.; Makhoute, A. [Physique Theorique, Universite Libre de Bruxelles, code postal 227, Boulevard du Triomphe, B-1050 Bruxelles (Belgium)

1997-12-01

173

E2F integrates cell cycle progression with DNA repair, replication, and G2\\/M checkpoints  

Microsoft Academic Search

The E2F transcription factor family is known to play a key role in the timely expression of genes required for cell cycle progression and proliferation, but only a few E2F target genes have been identified. We explored the possibility that E2F regulators play a broader role by identifying additional genes bound by E2F in living human cells. A protocol was

Bing Ren; Hieu Cam; Yasuhiko Takahashi; Thomas Volkert; Jolyon Terragni; Richard A. Young; Brian David Dynlacht

2002-01-01

174

The E2F transcriptional network: old acquaintances with new faces  

Microsoft Academic Search

The E2 factor (E2F) family of transcription factors are downstream targets of the retinoblastoma protein. E2F factors have been known for several years to be important regulators of S-phase entry. Recent studies have improved our understanding of the molecular mechanisms of action used by this transcriptional network. In addition, they have given us an appreciation of the fact that E2F

Desssislava K Dimova; Nicholas J Dyson

2005-01-01

175

Expression of Itch in Sertoli cells is controlled via the interaction of E2F1/DP1 complex with E2F and GATA motifs.  

PubMed

Itch, an ubiquitin E3 ligase, has been implicated in the regulation of the permeability of tight junction (TJ) barriers in Sertoli cells. It is involved in cAMP-mediated TJ disruption by targeting occludin for proteasomal degradation in the testis. However, the molecular mechanisms governing its transcription remain enigmatic. By the transient transfection of Itch promoter luciferase construct in TM4 cells, we showed that the minimal Itch promoter was located between nucleotides -151 and -1 (relative to the translation start site). One E2F motif and two each of GATA and Nkx motifs were identified within the core promoter region. Mutation and overexpression analyses have shown that the E2F and GATA-a motifs are involved in Itch gene transcription, but play different roles. The E2F motif is the crucial cis-acting element that drives the basal gene transcription, while the GATA-a motif functionally co-operates with E2F motif. By electromobility shift assays, we confirmed that E2F1 and DP1 form heterodimers and binds to E2F and GATA-a motifs. Taken together, the GATA-a motif assists/strengthens the binding of E2F1/DP1 complex to the E2F motif, resulting in efficient looping of promoter region of Itch gene for transcription. PMID:22319664

Li, Michelle Wm; Lee, Will M; Lui, Wing-Yee

2011-04-01

176

El, E2, E3 and M1 information from heavy ion coulomb excitation  

NASA Astrophysics Data System (ADS)

The richness of information pertaining to El, E2, E3 and M1 interaction deduced from Coulomb excitation experiments is illustrated. E2 and particularly M1 transition probabilities in 128Xe are presented. Large set of E3 and E1 additionally to E2 transition probabilities in 226Ra are shown.

Srebrny, J.; Czosnyka, T.; Karczmarczyk, W.; Napiorkowski, P.; Droste, Ch.; Wollersheim, H.-J.; Emling, H.; Grein, H.; Kulessa, R.; Cline, D.; Fahlander, C.

1993-05-01

177

Efficiency of E2-p7 Processing Modulates Production of Infectious Hepatitis C Virus.  

PubMed

Previous studies indicate that the processing of hepatitis C virus (HCV) E2-p7-NS2 precursor mediated by host signal peptidase is relatively inefficient, resulting in the accumulation of E2-p7-NS2 and E2-p7 precursors in addition to E2 in mammalian cells. In this study, we discovered that a significant inhibition of the processing at an E2-p7 junction site is detrimental for HCV production, whether it was caused by the mutations in p7 or by the strategic introduction of a mutation at a terminal residue of E2 to block the signal peptidase-mediated cleavage of this junction site. However, complete separation of E2 and p7 by inserting an encephalomyocarditis virus (EMCV) internal ribosome entry site (IRES) between these two proteins also moderately inhibited virus production. These results indicate that optimal processing of the E2-p7 junction site is critical for efficient HCV production. We further demonstrated that disrupting E2-p7 processing inhibits both NS2 localization to the putative virus assembly sites near lipid droplets (LD) and NS2 interaction with NS3 and E2. However, the impact, if any, of the p7-NS2 processing efficiency on HCV production seems relatively minor. In conclusion, these results imply that effective release of E2 and p7 from the precursor E2-p7 promotes HCV production by enhancing NS2-associated virus assembly complex formation near LD. PMID:23946462

Shanmugam, Saravanabalaji; Yi, Minkyung

2013-08-14

178

Estrogens in streams associated with a concentrated animal feeding operation in upstate New York, USA.  

PubMed

Estrogens (estrone, 17 alpha-estradiol, 17beta-estradiol, and estriol) in three headwater streams within a concentrated animal feed operation (CAFO) site were monitored on a monthly base for a year (November 2006-October 2007). This CAFO is certified as organic (no growth promoters are administrated) and uses many Whole Farm Planning practices (e.g., 12-month-capacity waste storage lagoons). In general, estrogen concentrations in the streams are low (<1 ng L(-1)), and appeared to increase in spring, likely due to the mobilization of estrogens from soils upon snow melting/precipitation. Estrogens were detected in the streams during dry periods, indicating the contribution of estrogens from groundwater. The low concentrations of estrogens in stream water were probably the result of the long residence time (approximately 8 months) of the manure in the lagoons where most of the estrogens were degraded during storage. An analysis of liquid manure at the beginning of manure application season (after approximately 8 months storage) showed that over 99.8% of the estrogens potentially excreted by the cows were degraded. Moreover, about 90% of the estrogens in the liquid manure were associated with particulates larger than 0.7 microm. Batch experiments with spiked deuterium-labeled 17beta-estradiol-16,16,17-d(3) (d(3)-E2 beta) in the liquid manure demonstrated sorption of d(3)-E2 beta onto particulates in the liquid manure, and rapid degradation of d(3)-E2 beta in the aqueous phase and on particulates of the liquid manure under aerobic conditions. PMID:20172589

Zhao, Sherry; Zhang, Pengfei; Melcer, Michael E; Molina, John F

2010-02-20

179

Fate of endocrine disrupting compounds in membrane bioreactor systems.  

PubMed

Yeast estrogen screen (YES) bioassay and liquid chromatography-mass spectrum-mass spectrum (LC-MS-MS) analysis were performed to investigate the fate of active and potential endocrine disrupting compounds in 3 pilot-scale and 2 lab-scale membrane bioreactor (MBR) systems. Compared with the overall estrogenicities of sewage treatment plant (STP) effluents from references, the MBR systems studied have relatively good performance in the removal of estrogenicity. Estrone (E1) was removed with relatively high efficiency (80.2-91.4%), but 17beta-estradiol (E2) was removed with moderate efficiency (49.3-66.5%) by the MBRs. However, the experimental results indicated that after the treatment by MBR, substantial amounts of E1, estrone-3-sulfate (E1-3S), estrone-3-glucuronide (E1-3G), and 17beta-estradiol-glucuronides (E2-G) passed through treatment systems and entered into the aquatic environment. The reduction in the levels of overall equivalent E1 (68.4%) and that of overall equivalent E2 (80.8%) was demonstrated for the pilot-scale MBR-B. For alkylphenol compounds, bisphenol A (BPA) was removed well with a removal efficiency of 68.9 -90.1%, but 4-nonylphenol (4-NP) concentration was amplified (removal efficiency of -439.5 to -161.1%) after MBR treatment which could be caused by the transformation of its parent compounds, nonylphenol polyethoxylates (NPnEOs). The amounts of adsorbed estrogens per kg dry mass was relatively low, due to short hydraulic retention time and high mixed liquor suspended solids in MBRs, compared to that in STPs. PMID:17612196

Hu, J Y; Chen, X; Tao, G; Kekred, K

2007-06-01

180

Specific regulation of E2F family members by cyclin-dependent kinases.  

PubMed Central

The transcription factor E2F-1 interacts stably with cyclin A via a small domain near its amino terminus and is negatively regulated by the cyclin A-dependent kinases. Thus, the activities of E2F, a family of transcription factors involved in cell proliferation, are regulated by at least two types of cell growth regulators: the retinoblastoma protein family and the cyclin-dependent kinase family. To investigate further the regulation of E2F by cyclin-dependent kinases, we have extended our studies to include additional cyclins and E2F family members. Using purified components in an in vitro system, we show that the E2F-1-DP-1 heterodimer, the functionally active form of the E2F activity, is not a substrate for the active cyclin D-dependent kinases but is efficiently phosphorylated by the cyclin B-dependent kinases, which do not form stable complexes with the E2F-1-DP-1 heterodimer. Phosphorylation of the E2F-1-DP-1 heterodimer by cyclin B-dependent kinases, however, did not result in down-regulation of its DNA-binding activity, as is readily seen after phosphorylation by cyclin A-dependent kinases, suggesting that phosphorylation per se is not sufficient to regulate E2F DNA-binding activity. Furthermore, heterodimers containing E2F-4, a family member lacking the cyclin A binding domain found in E2F-1, are not efficiently phosphorylated or functionally down-regulated by cyclin A-dependent kinases. However, addition of the E2F-1 cyclin A binding domain to E2F-4 conferred cyclin A-dependent kinase-mediated down-regulation of the E2F-4-DP-1 heterodimer. Thus, both enzymatic phosphorylation and stable physical interaction are necessary for the specific regulation of E2F family members by cyclin-dependent kinases.

Dynlacht, B D; Moberg, K; Lees, J A; Harlow, E; Zhu, L

1997-01-01

181

Human proteome-scale structural modeling of E2-E3 interactions exploiting interface motifs  

PubMed Central

Ubiquitination is crucial for many cellular processes such as protein degradation, DNA repair, transcription regulation and cell signaling. Ubiquitin attachment takes place via a sequential enzymatic cascade involving ubiquitin-activation (by E1 enzymes), ubiquitin-conjugation (by E2 enzymes), and ubiquitin substrate-tagging (by E3 enzymes). E3 ligases mediate ubiquitin transfer from E2s to substrates and as such confer substrate specificity. Although E3s can interact and function with numerous E2s, it is still unclear how they choose which E2 to use. Identifying all E2 partners of an E3 is essential for inferring the principles guiding E2 selection by an E3. Here we model the interactions of E3 and E2 proteins in a large, proteome-scale strategy based on interface structural motifs, which allows elucidation of 1) which E3s interact with which E2s in the human ubiquitination pathway; and 2) how they interact with each other. Interface analysis of E2-E3 complexes reveals that loop L1 of E2s is critical for binding; the residue in the sixth position in loop L1 is widely utilized as an interface hot spot and appears indispensible for E2 interactions. Other loop L1 residues also confer specificity on the E2-E3 interactions: HECT E3s are in contact with the residue in the second position in loop L1 of E2s; but this is not the case for the RING finger type E3s. Our modeled E2-E3 complexes illuminate how slight sequence variations in E2 residues may contribute to specificity in E3 binding. These findings may be important for discovering drug candidates targeting E3s, which have been implicated in many diseases.

Kar, Gozde; Nussinov, Ruth

2012-01-01

182

Cloning, chromosomal location, and characterization of mouse E2F1.  

PubMed Central

E2F has been implicated in growth control because of its association with the retinoblastoma protein and the presence of E2F binding sites in the promoters of several growth-regulated genes. Proteins that bind to an E2F site have been cloned from human and mouse cells. However, these two proteins (human E2F1 and mouse DP-1) are quite different in sequence. We have now cloned a mouse cDNA encoding a protein 86% identical to the human E2F1 protein. The mouse E2F1 cDNA encodes a 430-amino-acid protein with a predicted molecular weight of 46,322 and detects mRNAs of 2.7 and 2.2 kb. Using primers complementary to sequences in the mouse E2F1 3' untranslated region, we mapped the mouse E2F1 gene to chromosome 2, near the Agouti and c-src loci. To understand the role of the different E2F family members in the growth of mouse NIH 3T3 cells, we examined the levels of E2F1 and DP-1 mRNAs in different stages of the cell cycle. Since the levels of E2F1 but not DP-1 mRNA correlated with changes in transcription from the dhfr promoter, we examined whether E2F1 could activate various growth-regulated promoters. We found that E2F1 could activate some (dhfr, thymidine kinase, and DNA polymerase alpha) but not all (thymidylate synthase, cad, and c-myc) of these promoters. On the basis of changes in levels of E2F1 and its ability to transactivate growth-regulated promoters, we propose that E2F1 may mediate growth factor-initiated signal transduction. Images

Li, Y; Slansky, J E; Myers, D J; Drinkwater, N R; Kaelin, W G; Farnham, P J

1994-01-01

183

Regulation of transcription factor E2F3a and its clinical relevance in ovarian cancer  

Microsoft Academic Search

Recently we showed an integral epidermal growth factor receptor (EGFR)–E2F3a signaling path, in which E2F3a was found to be essential in EGFR-mediated proliferation in ovarian cancer cells. The present work evaluates the clinical relevance of this novel axis and of E2F3a itself in a large set of 130 ovarian cancer specimens. For this purpose E2F3a and its counterpart, E2F3b, were

D Reimer; M Hubalek; H Kiefel; S Riedle; S Skvortsov; M Erdel; G Hofstetter; N Concin; H Fiegl; E Müller-Holzner; C Marth; P Altevogt; A G Zeimet

2011-01-01

184

Phosphorylation-Dependent SUMOylation of the Transcription Factor NF-E2  

PubMed Central

Nuclear factor erythroid-derived 2 (NF-E2), a heterodimer composed of p45 and p18, is a transcriptional activator in hematopoietic progenitors. The transcriptional activity of NF-E2 is not only upregulated by SUMOylation but also stimulated by the cAMP-dependent protein kinase A (PKA). However, the relationship between SUMOylation and phosphorylation in the activation of NF-E2 is unclear. In the present studies, we have demonstrated that PKA enhances NF-E2 SUMOylation in an in vitro system using purified proteins, suggesting a possible mechanism for PKA-dependent activation of the NF-E2 transcription factor through SUMOylation.

Su, Yee-Fun; Shyu, Yu-Chiau; Shen, Che-Kun James; Hwang, Jaulang

2012-01-01

185

p27Kip1 induces an accumulation of the repressor complexes of E2F and inhibits expression of the E2F-regulated genes.  

PubMed Central

p27Kip1 is an inhibitor of the cyclin-dependent kinases and it plays an inhibitory role in the progression of cell cycle through G1 phase. To investigate the mechanism of cell cycle inhibition by p27Kip1, we constructed a cell line that inducibly expresses p27Kip1 upon addition of isopropyl-1-thio-beta-D-galactopyranoside in the culture medium. Isopropyl-1-thio-beta-D-galactopyranoside-induced expression of p27Kip1 in these cells causes a specific reduction in the expression of the E2F-regulated genes such as cyclin E, cyclin A, and dihydrofolate reductase. The reduction in the expression of these genes correlates with the p27Kip1-induced accumulation of the repressor complexes of the E2F family of factors (E2Fs). Our previous studies indicated that p21WAF1 could disrupt the interaction between cyclin/cyclin-dependent kinase 2 (cdk2) and the E2F repressor complexes E2F-p130 and E2F-p107. We show that p27Kip1, like p21WAF1, disrupts cyclin/cdk2-containing complexes of E2F-p130 leading to the accumulation of the E2F-p130 complexes, which is found in growth-arrested cells. In transient transfection assays, expression of p27Kip1 specifically inhibits transcription of a promoter containing E2F-binding sites. Mutants of p27Kip1 harboring changes in the cyclin- and cdk2-binding motifs are deficient in inhibiting transcription from the E2F sites containing reporter gene. Moreover, these mutants of p27Kip1 are also impaired in disrupting the interaction between cyclin/cdk2 and the repressor complexes of E2Fs. Taken together, these observations suggest that p27Kip1 reduces expression of the E2F-regulated genes by generating repressor complexes of E2Fs. Furthermore, the results also demonstrate that p27Kip1 inhibits expression of cyclin A and cyclin E, which are critical for progression through the G1-S phases. Images

Shiyanov, P; Hayes, S; Chen, N; Pestov, D G; Lau, L F; Raychaudhuri, P

1997-01-01

186

Estrogen directly acts on osteoclasts via inhibition of inward rectifier K+ channels.  

PubMed

Using the whole-cell patch-clamp technique in freshly isolated rat osteoclasts we examined the effects of estrogen on ionic channels. The predominant current was an inward rectifier K+ current (IKir). In the absence of non-osteoclastic cells, extracellularly applied 17beta-estradiol (>0.1 microM) inhibited IKir, indicating that estrogen acts directly on osteoclasts. Application of 17beta-estradiol (10 microM) for 10 min reduced IKir at the membrane potential of -120 mV to 70 +/- 15% of control. Removal of 17beta-estradiol partially restored the inhibition. The inhibition of IKir was dependent on concentration and application time. Intracellularly applied 17beta-estradiol had no effect on IKir. 17alpha-estradiol also inhibited the IKir, whereas progesterone and testosterone had no effect. The inhibitory action of 17beta-estradiol was not affected by guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS), adenosine 3',5'-cyclic monophosphothioate Rp diastereomer (Rp-cAMPS), okadaic acid, staurosporine and phorbol ester, and was independent of intracellular Ca2+ concentration ([Ca2+]i). With no influence from soluble factors secreted from non-osteoclastic cells, preincubation of the osteoclasts for more than 60 min with much lower concentrations of 17beta-estradiol (1 and 10 nM) caused a reduction of IKir. In current-clamp configuration, application of 17beta-estradiol (10 microM) depolarized the membrane associated with a decrease in a membrane conductance, indicating that 17beta-estradiol inhibits IKir and depolarizes the membrane of osteoclasts. These results suggest that the 17beta-estradiol-induced inhibition of IKir might be mediated via non-genomic mechanisms. This direct action of 17beta-estradiol on osteoclasts may contribute to the regulation of [Ca2+]i and partially account for the protective effects of estrogen against bone loss. PMID:10882036

Okabe, K; Okamoto, F; Kajiya, H; Takada, K; Soeda, H

2000-06-01

187

E2 interference effects in the 12C(?,?0)16O reaction.  

PubMed

The E1-E2 interference sign between the E(c.m.)=2.68-MeV E2 resonance and an underlying E1 strength has been measured for the first time. An E1-E2 asymmetry parameter of a=0.07±0.05 was extracted from the thick-target ?-ray yields of the narrow resonance at angles of 45° and 135°. The positive sign of a corresponded to constructive interference at forward angles and, further, allowed the interference between the resonance and an E2 background to be identified as constructive below the resonance energy. The E2-E2 interference was then used to evaluate the global S(E2) data within the vicinity of the resonance 2.5?E(c.m.)?3.0??MeV. An analysis of the global S(E2) data that agreed with the interference scenario has determined the E2-E2 interference scheme of the 4.34-MeV resonance and background, resulting in a value of S(E2)(300)=62(-6)(+9)??keV b. PMID:23083238

Sayre, D B; Brune, C R; Carter, D E; Jacobs, D K; Massey, T N; O'Donnell, J E

2012-10-03

188

Inhibition of mesangial cell proliferation by E2F decoy oligodeoxynucleotide in vitro and in vivo.  

PubMed Central

The transcription factor E2F coordinately activates several cell cycle-regulatory genes. We attempted to inhibit the proliferation of mesangial cells in vitro and in vivo by inhibiting E2F activity using a 25-bp decoy oligodeoxynucleotide that contained consensus E2F binding site sequence (E2F-decoy) as a competitive inhibitor. The decoy's effect on human mesangial cell proliferation was evaluated by [3H]thymidine incorporation. The E2F decoy inhibited proliferation in a concentration-dependent manner, whereas a mismatch control oligodeoxynucleotide had little effect. Electrophoretic mobility shift assays demonstrated that the decoy's inhibitory effect was due to the binding of the decoy oligodeoxynucleotide to E2F. The effect of the E2F decoy was then tested in a rat anti-Thy 1.1 glomerulonephritis model. The E2F decoy oligodeoxynucleotide was introduced into the left kidney 36 h after the induction of glomerulonephritis. The administration of E2F decoy suppressed the proliferation of mesangial cells by 71%. Furthermore, treatment with the E2F decoy inhibited the glomerular expression of proliferating cell nuclear antigen at the protein level as well as the mRNA level. These findings indicate that decoy oligonucleotides can suppress the activity of the transcription factor E2F, and may thus have a potential in treating glomerulonephritis.

Maeshima, Y; Kashihara, N; Yasuda, T; Sugiyama, H; Sekikawa, T; Okamoto, K; Kanao, K; Watanabe, Y; Kanwar, Y S; Makino, H

1998-01-01

189

E2F-1 has dual roles depending on the cell cycle  

PubMed Central

The E2F family of transcription factors play a critical role in the control of cell proliferation. E2F-1 is the major cellular target of pRB and is regulated by pRB during cell proliferation. E2F-1-mediated activation and repression of target genes occurs in different settings. The role of E2F-1 and E2F-1/pRB complexes in regulation of different target genes, and in cycling versus quiescent cells, is unclear. In this study, effects of free E2F-1 (doesn't complex with pRb) and E2F-1/pRb complex, on E2F-1 target gene expression were compared in different cell growth conditions. Findings suggest that E2F-1 acts in different ways, not only depending on the target gene but also depending on different stages of the cell cycle. For example, E2F-1 acts as part of the repression complex with pRB in the expression of DHFR, b-myb, TK and cdc2 in asynchronously growing cells; on the other hand, E2F-1 acts as an activator in the expression of the same genes in cells that are re-entering the cycle.

Sahin, Fikret; Sladek, Todd L.

2010-01-01

190

Functional Replacement of the Mouse E2A Gene with a Human HEB cDNA  

PubMed Central

The mammalian E2A, HEB, and E2-2 genes encode a unique class of basic helix-loop-helix (bHLH) transcription factors that are evolutionarily conserved and essential for embryonic and postnatal development. While the structural and functional similarities among the gene products are well demonstrated, it is not clear why deletion of E2A, but not HEB or E2-2, leads to a complete arrest in B-lymphocyte development. To understand the molecular basis of the functional specificity between E2A and HEB/E2-2 in mammalian development, we generated and tested a panel of E2A knockin mutations including subtle mutations in the E12 and E47 exons and substitution of both E12 and E47 exons with a human HEB cDNA. We find that the alternatively spliced E12 and E47 bHLH proteins of the E2A gene play similar and additive roles in supporting B lymphopoiesis. Further, we find that HEB driven by the endogenous E2A promoter can functionally replace E2A in supporting B-cell commitment and differentiation toward completion. Finally, the postnatal lethality associated with E2A disruption is fully rescued by the addition of HEB. This study suggests that the functional divergence among E12, E47, and HEB in different cell types is partially defined by the context of gene expression.

Zhuang, Yuan; Barndt, Robert J.; Pan, Lihua; Kelley, Robert; Dai, Meifang

1998-01-01

191

ERK signaling is triggered by hepatitis C virus E2 protein through DC-SIGN.  

PubMed

Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) is a binding receptor for hepatitis C virus (HCV). Binding of HCV envelope protein E2 to target cells is a prerequisite to DC-SIGN-mediated signaling. Using cell lines with stable or transient expression of DC-SIGN, we investigated effects of soluble HCV E2 protein on ERK pathway. MEK and ERK are activated by the E2 in NIH3T3 cells stably expressing DC-SIGN. Treatment of the cells with antibody to DC-SIGN results in inhibition of the E2 binding as well as the E2-induced MEK and ERK activation. In HEK293T cells transiently expressing DC-SIGN, activation of MEK and ERK is also induced by the E2. Activation of ERK pathway by HCV E2 through DC-SIGN provides useful information for understanding cellular receptor-mediated signaling. PMID:23378214

Zhao, Lan-Juan; Wang, Wen; Ren, Hao; Qi, Zhong-Tian

2013-02-03

192

Acetylation status of E2F-1 has an important role in the regulation of E2F-1-mediated transactivation of tumor suppressor p73.  

PubMed

Tumor suppressor p73 plays an important role in the regulation of DNA damage response. E2F-1 acts as a transcriptional regulator for p73. In the present study, we have found that acetylation of E2F-1 has a critical role in the E2F-1-mediated transactivation of p73. In response to adriamycin (ADR), p73 was stabilized in HeLa cells and the expression levels of its target genes increased in association with an induction of apoptosis. Of note, E2F-1 and several its target genes were transactivated in response to ADR, whereas p73 mRNA level remained unchanged. Immunoprecipitation analysis revealed that ADR has a marginal effect on acetylation status of E2F-1. Intriguingly, acetylation level of E2F-1 remarkably increased in the presence of trichostatin A (TSA) and thereby inducing the expression level of p73 mRNA. Taken together, our present findings suggest that acetylation status of E2F-1 contributes to the selective activation of its target genes. PMID:19523927

Ozaki, Toshinori; Okoshi, Rintaro; Sang, Meixiang; Kubo, Natsumi; Nakagawara, Akira

2009-06-11

193

Light-Dependent Regulation of DEL1 Is Determined by the Antagonistic Action of E2Fb and E2Fc1[W][OA  

PubMed Central

Endoreduplication represents a variation on the cell cycle in which multiple rounds of DNA replication occur without subsequent chromosome separation and cytokinesis, thereby increasing the cellular DNA content. It is known that the DNA ploidy level of cells is controlled by external stimuli such as light; however, limited knowledge is available on how environmental signals regulate the endoreduplication cycle at the molecular level. Previously, we had demonstrated that the conversion from a mitotic cell cycle into an endoreduplication cycle is controlled by the atypical E2F transcription factor, DP-E2F-LIKE1 (DEL1), that represses the endocycle onset. Here, the Arabidopsis (Arabidopsis thaliana) DEL1 gene was identified as a transcriptional target of the classical E2Fb and E2Fc transcription factors that antagonistically control its transcript levels through competition for a single E2F cis-acting binding site. In accordance with the reported opposite effects of light on the protein levels of E2Fb and E2Fc, DEL1 transcription depended on the light regime. Strikingly, modified DEL1 expression levels uncoupled the link between light and endoreduplication in hypocotyls, implying that DEL1 acts as a regulatory connection between endocycle control and the photomorphogenic response.

Berckmans, Barbara; Lammens, Tim; Van Den Daele, Hilde; Magyar, Zoltan; Bogre, Laszlo; De Veylder, Lieven

2011-01-01

194

Pumilio facilitates miRNA regulation of the E2F3 oncogene.  

PubMed

E2F transcription factors are important regulators of cell proliferation and are frequently dysregulated in human malignancies. To identify novel regulators of E2F function, we used Drosophila as a model system to screen for mutations that modify phenotypes caused by reduced levels of dE2F1. This screen identified components of the Pumilio translational repressor complex (Pumilio, Nanos, and Brain tumor) as suppressors of dE2F1-RNAi phenotypes. Subsequent experiments provided evidence that Pumilio complexes repress dE2F1 levels and that this mechanism of post-transcriptional regulation is conserved in human cells. The human Pumilio homologs Pum 1 and Pum 2 repress the translation of E2F3 by binding to the E2F3 3' untranslated region (UTR) and also enhance the activity of multiple E2F3 targeting microRNAs (miRNAs). E2F3 is an oncogene with strong proliferative potential and is regularly dysregulated or overexpressed in cancer. Interestingly, Pumilio/miRNA-mediated regulation of E2F3 is circumvented in cancer cells in several different ways. Bladder carcinomas selectively down-regulate miRNAs that cooperate with Pumilio to target E2F3, and multiple tumor cell lines shorten the 3' end of the E2F3 mRNA, removing the Pumilio regulatory elements. These studies suggest that Pumilio-miRNA repression of E2F3 translation provides an important level of E2F regulation that is frequently abrogated in cancer cells. PMID:22345517

Miles, Wayne O; Tschöp, Katrin; Herr, Anabel; Ji, Jun-Yuan; Dyson, Nicholas J

2012-02-15

195

APC/CCdc20 targets E2F1 for degradation in prometaphase  

PubMed Central

The mechanisms that control E2F-1 activity are complex. We previously showed that Chk1 and Chk2 are required for E2F1 stabilization and p73 target gene induction following DNA damage. To gain further insight into the processes regulating E2F1 protein stability, we focused our investigation on the mechanisms responsible for regulating E2F1 turnover. Here we show that E2F1 is a substrate of the anaphase-promoting complex or cyclosome (APC/C), a ubiquitin ligase that plays an important role in cell cycle progression. Ectopic expression of the APC/C activators Cdh1 and Cdc20 reduced the levels of co-expressed E2F-1 protein. Co-expression of DP1 with E2F1 blocked APC/C-induced E2F1 degradation, suggesting that the E2F1/DP1 heterodimer is protected from APC/C regulation. Following Cdc20 knockdown, E2F1 levels increased and remained stable in extracts over a time course, indicating that APC/CCdc20 is a primary regulator of E2F1 stability in vivo. Moreover, cell synchronization experiments showed that siRNA directed against Cdc20 induced an accumulation of E2F1 protein in prometaphase cells. These data suggest that APC/CCdc20 specifically targets E2F1 for degradation in early mitosis and reveal a novel mechanism for limiting free E2F1 levels in cells, failure of which may compromise cell survival and/or homeostasis.

Peart, Melissa J; Poyurovsky, Masha V; Kass, Elizabeth M; Urist, Marshall; Verschuren, Emmy W; Summers, Matthew K; Jackson, Peter K

2010-01-01

196

Lentivirus-mediated RNA interference of E2F-1 suppresses Tca8113 cell proliferation.  

PubMed

In most types of human cancer, inactivation of pRb/E2F complexes occurs, and released E2Fs initiate transcription of genes required for cell cycle progression. Evidence reveals that phosphorylated pRb deregulates E2F-1, and the levels of E2F-1 expression can accurately predict prognosis of oral squamous cell carcinoma (OSCC). Paradoxically, numerous reports indicate that E2F-1 is also capable of inducing apoptosis under certain cellular circumstances. In the present study, lentivirus-mediated shRNA was used to downregulate endogenous E2F-1 expression in order to study the function of E2F-1 in the pRb/E2F-1 pathway in the OSCC cell line Tca8113, and to investigate the alteration of Tca8113 cells in proliferation and apoptosis. The data from real-time quantitative RT-PCR and Western blot analysis showed that E2F-1-shRNA led to the inhibition of endogenous E2F-1 mRNA and protein expression, and E2F-1 may be associated with proliferation and apoptosis pathways. Growth kinetics data showed that Tca8113-E2F-1-shRNA cells presented more active proliferation properties than Tca8113-NC cells, and flow cytometry data demonstrated that the percentages of cells in the G1 phase, G2 phase and undergoing apoptosis differed between groups. In conclusion, silencing of E2F-1 inhibits proliferation and induces apoptosis. E2F-1 may also be involved in multi-level regulation networks; therefore, its role in OSCC requires further clarification. PMID:22076063

Yuan, Hua; Jiang, Fei; Wang, Ruixia; Shen, Ming; Chen, Ning

2011-11-07

197

CDK8 regulates E2F1 transcriptional activity through S375 phosphorylation.  

PubMed

Activation of the Wnt/?-catenin pathway is a critical step in the development of colorectal cancers. A key mediator of this activation is the recently described oncogene CDK8, which is amplified in a large number of colorectal tumors. CDK8 affects ?-catenin activation by interaction of the CDK8 submodule of the mediator complex with ?-catenin/TCF transcriptional complex, and by CDK8 interacting with and phosphorylating E2F1, which acts as a repressor of ?-catenin/TCF transcriptional activity. The amino-acid residue in E2F1 that CDK8 phosphorylates and how this phosphorylation impacts E2F1 activity in general is not known. Here, we describe that CDK8 phosphorylates serine 375 in E2F1 both in vitro and in cells, and that phosphorylation of this residue is required for E2F1 interaction with CDK8, and that the phosphorylation is dependent on CDK8 kinase activity. The phosphorylation of S375 by CDK8 regulates E2F1 ability to repress transcription of ?-catenin/TCF-dependent genes, as well as activation of E2F1-dependent genes. This regulation is due to inactivation of E2F1 transcriptional activation, and not to the interference of E2F1's ability to bind to E2F1-binding sites in various promoters or to interact with DP1. PMID:22945643

Zhao, J; Ramos, R; Demma, M

2012-09-03

198

Increased gene copy number of the transcription factor E2F1 in malignant melanoma.  

PubMed

Translocations and unique chromosome break points in melanoma will aid in the identification of the genes that are important in the neoplastic process. We have previously shown a unique translocation in malignant melanoma cells der(12)t(12;20). The transcription factor E2F1 maps to 20q11. Increased expression of E2F has been associated with the autonomous growth of melanoma cells, however, the molecular basis has not yet been elucidated. To this end, we investigated E2F1 gene copy number and structure in human melanoma cell lines and metastatic melanoma cases. Fluorescent in situ hybridization (FISH) analysis using a specific E2F1 probe indicated increased E2F1 gene copies in melanoma cell lines compared to normal melanocytes. We also observed increased copies of the E2F1 gene in lymph node metastases of melanoma. In addition, Western blot analysis demonstrated increased E2F1 protein levels in 8 out of 9 melanoma cell lines relative to normal melanocytes. Inhibition of E2F1 expression with RNAi also reduced melanoma cell growth. Our results suggest that the release of E2F activity by elevated E2F1 gene copy numbers may play a functional role in melanoma growth. PMID:16481740

Nelson, Mark A; Reynolds, Steven H; Rao, Uma N M; Goulet, Anne-Christine; Feng, Yongmei; Beas, Anthony; Honchak, Barbara; Averill, Jim; Lowry, David T; Senft, Jamie R; Jefferson, Amy M; Johnson, Robert C; Sargent, Linda M

2006-04-17

199

Transcriptional regulation of human RANK ligand gene expression by E2F1  

SciTech Connect

Receptor activator of nuclear factor kappa B ligand (RANKL) is a critical osteoclastogenic factor involved in the regulation of bone resorption, immune function, the development of mammary gland and cardiovascular system. To understand the transcriptional regulation of RANKL, we amplified and characterized a 1890 bp 5'-flanking sequence of human RANKL gene (-1782 bp to +108 bp relative to the transcription start site). Using a series of deletion mutations of the 1890 bp RANKL promoter, we identified a 72 bp region (-172 to -100 bp) mediating RANKL basal transcriptional activity. Sequence analysis revealed a putative E2F binding site within this 72 bp region in the human RANKL promoter. Overexpression of E2F1 increased RANKL promoter activity, while down-regulation of E2F1 expression by small interfering RNA decreased RANKL promoter activity. RT-PCR and enzyme linked immunosorbent assays (ELISA) further demonstrated that E2F1 induced the expression of RANKL. Electrophoretic gel mobility shift assays (EMSA) and antibody competition assays confirmed that E2F1 proteins bind to the consensus E2F binding site in the RANKL promoter. Mutation of the E2F consensus binding site in the RANKL promoter profoundly reduced the basal promoter activity and abolished the transcriptional modulation of RANKL by E2F1. These results suggest that E2F1 plays an important role in regulating RANKL transcription through binding to the E2F consensus binding site.

Hu Yan [Department of Stress Biology, Roswell Park Cancer Institute, Buffalo, NY 14263 (United States); Sun Meng [Department of Urology and Cancer Center, University of California at Davis, School of Medicine, 4860 Y Street, Suite 3500, Sacramento, CA 95817 (United States); Graduate Program of Pharmacology and Toxicology, University of California at Davis, Sacramento, CA 95817 (United States); Nadiminty, Nagalakshmi; Lou Wei [Department of Urology and Cancer Center, University of California at Davis, School of Medicine, 4860 Y Street, Suite 3500, Sacramento, CA 95817 (United States); Pinder, Elaine [Department of Urology and Cancer Center, University of California at Davis, School of Medicine, 4860 Y Street, Suite 3500, Sacramento, CA 95817 (United States); Graduate Program of Pharmacology and Toxicology, University of California at Davis, Sacramento, CA 95817 (United States); Gao, Allen C. [Department of Urology and Cancer Center, University of California at Davis, School of Medicine, 4860 Y Street, Suite 3500, Sacramento, CA 95817 (United States); Graduate Program of Pharmacology and Toxicology, University of California at Davis, Sacramento, CA 95817 (United States)], E-mail: acgao@ucdavis.edu

2008-06-06

200

Constitutive E2F1 Overexpression Delays Endochondral Bone Formation by Inhibiting Chondrocyte Differentiation  

PubMed Central

Longitudinal bone growth results from endochondral ossification, a process that requires proliferation and differentiation of chondrocytes. It has been shown that proper endochondral bone formation is critically dependent on the retinoblastoma family members p107 and p130. However, the precise functional roles played by individual E2F proteins remain poorly understood. Using both constitutive and conditional E2F1 transgenic mice, we show that ubiquitous transgene-driven expression of E2F1 during embryonic development results in a dwarf phenotype and significantly reduced postnatal viability. Overexpression of E2F1 disturbs chondrocyte maturation, resulting in delayed endochondral ossification, which is characterized by reduced hypertrophic zones and disorganized growth plates. Employing the chondrogenic cell line ATDC5, we investigated the effects of enforced E2F expression on the different phases of chondrocyte maturation that are normally required for endochondral ossification. Ectopic E2F1 expression strongly inhibits early- and late-phase differentiation of ATDC5 cells, accompanied by diminished cartilage nodule formation as well as decreased type II collagen, type X collagen, and aggrecan gene expression. In contrast, overexpression of E2F2 or E2F3a results in only a marginal delay of chondrocyte maturation, and increased E2F4 levels have no effect. These data are consistent with the notion that E2F1 is a regulator of chondrocyte differentiation.

Scheijen, Blanca; Bronk, Marieke; van der Meer, Tiffany; Bernards, Rene

2003-01-01

201

Altered E2 glycoprotein of Sindbis virus and its use in complementation studies.  

PubMed Central

We have detected a Sindbis virus variant that contains a smaller-molecular-weight form of the viral glycoprotein E2. The molecular weight of the PE2 precursor and the glycosylation pattern of the smaller E2 are normal, thus indicating that this E2 is formed by an aberrant proteolytic cleavage. The altered E2 was detected in an RNA+ temperature-sensitive mutant that was defective in proteolytic cleavage, but the abnormal PE2-to-E2 reaction could be separated from the ts mutation and is not itself a temperature-sensitive defect. We used the variant E2 as a marker to monitor the complementation reaction between an RNA+ and an RNA- mutant and discovered that complementation was not reciprocal; the RNA defect was corrected by the RNA+ mutant gene products but the RNA+ defect was not complemented by any RNA- gene products. Other studies have shown that the smaller E2 is not preferentially selected during viral maturation and budding. No significant changes have been detected in the biological activity of virions with this altered E2 protein. Comparison of the electrophoretic migration of the E1 and E2 Sindbis viral glycoproteins in a two-dimensional polyacrylamide slab gel system that was first run in the absence of sulfhydryl-reducing reagent and then with beta-mercaptoethanol indicated that the mobility of E1, but not that of E2, was significantly altered by reduction. Images

Bracha, M; Schlesinger, M J

1978-01-01

202

Interaction of the 72-kilodalton human cytomegalovirus IE1 gene product with E2F1 coincides with E2F-dependent activation of dihydrofolate reductase transcription.  

PubMed Central

Three polypeptides are produced from the major immediate-early (IE) region of human cytomegalovirus by alternative splicing. The IE gene products regulate subsequent viral and cellular gene expression. We previously reported that cotransfection of a genomic clone of the major IE region stimulated transient expression of chloramphenicol acetyltransferase driven by the dihydrofolate reductase (DHFR) promoter and that an intact E2F site was required for the trans activation (M. Wade, T. F. Kowalik, M. Mudryj, E.-S. Huang, and J. C. Azizkhan, Mol. Cell. Biol. 12:4364-4374, 1992). With the availability of cDNA clones for the individual major IE proteins, we sought to determine which of these proteins exerted this effect and whether the IE protein(s) interacted with E2F. In this study, we use cotransfection to demonstrate that the 55- and 86-kDa major IE proteins from the IE2 region can each moderately trans activate the DHFR promoter and that the 72-kDa IE1 protein stimulates DHFR transcription to a much higher level. Furthermore, trans activation through the 72-kDa IE1 protein is in part E2F dependent, while activation by the 55- and 86-kDa IE proteins is E2F independent. We also demonstrate by in vitro pull-down assays that the 72-kDa IE1 protein can specifically interact with the DNA binding domain of E2F1 (amino acids 88 to 191) in the presence of nuclear extract. Moreover, antibodies to either E2F1 or IE72 will immunoprecipitate both E2F and IE72 from cells that stably express IE72, and antibody to E2F1 will immunoprecipitate IE72 from normal human fibroblast cells infected with human cytomegalovirus.

Margolis, M J; Pajovic, S; Wong, E L; Wade, M; Jupp, R; Nelson, J A; Azizkhan, J C

1995-01-01

203

Characterization of a membrane-associated estrogen receptor in a rat hypothalamic cell line (D12).  

PubMed

The ability of estrogens to produce rapid changes in cellular function has been firmly established. The question remains whether these changes are mediated by a modified form of the nuclear estrogen receptor (ER) that is associated with the plasma membrane (mER) or by a completely novel membrane receptor. Therefore, we characterized the biochemical properties of the nuclear and membrane-associated ERs expressed endogenously in a rat hypothalamic endothelial cell line (D12). Radioligand binding experiments using D12 membrane fractions showed that these cells exhibit properties consistent with a binding site specific for estrogens (mER). Equilibrium binding assays using [125I]16-alpha-iodo-3,17- beta-estradiol revealed saturable binding to mER, an affinity value similar to nuclear ER, with differing receptor expression levels. Competition assays revealed that 9 of 12 ER ligands tested had comparable affinities for mER and ER. For example, 17-alpha-estradiol and estrone had similar binding characteristics for both receptors while differences were noted for raloxifene, 17beta-estradiol (E2), and genistein. Western blot and immunocytochemical analyses using antibodies specific for ERalpha confirmed that D12 cells expressed a membrane-associated protein with a molecular mass (67 kDa) similar to that of ERalpha that colocalized with caveolae-enriched membranes. A rapid increase in intracellar Ca2+ levels in the presence of E2 suggests that mER can mediate physiologic changes through calcium mobilization. These data support the expression of mER in these brain-derived endothelial cells that is similar to, but biochemically distinguishable from, nuclear ERalpha. PMID:14709794

Deecher, Darlene C; Swiggard, Pamela; Frail, Donald E; O'Connor, Lawrence T

2003-12-01

204

Effect of hormonal replacement therapy in the hippocampus of ovariectomized epileptic female rats using the pilocarpine experimental model.  

PubMed

Amado and Cavalheiro [Amado, D., Cavalheiro, E.A., 1998. Hormonal and gestational parameters in female rats submitted to the pilocarpine model of epilepsy. Epilepsy Res. 32, 266-274], studying the establishment of the pilocarpine epilepsy model in female rats observed that the estrous cycle was dramatically altered during the three periods of this experimental model. This work was delineated to study the function of sexual hormones in the development of the epilepsy model induced by pilocarpine in ovariectomized rats. Experimental groups were: (a) control animals during estrus phase of the estrous cycle (E) and ovariectomized female rats (OVX) treated with saline instead of pilocarpine in the same volume, (b) experimental animals, that developed status epilepticus (SE) and were studied during the chronic phase of this model: intact chronic rats (CHRON) and ovariectomized chronic rats (OVX+CHRON) and (c) ovariectomized chronic rats, that were submitted to hormonal replacement therapy treated with: medroxyprogesterone (OVX+CHRON+MPA); 17beta-estradiol (OVX+CHRON+E2), or both (OVX+CHRON+E2+MPA). All ovariectomized animals showed genital atrophy 4 days after the surgical procedure. Moreover, all animals that developed SE and survived showed spontaneous recurrent seizures during the chronic phase. Concerning to seizure frequency, animals receiving medroxyprogesterone associated with 17beta-estradiol showed decreased seizures' number. However, animals that received only medroxyprogesterone therapy also showed reduction in the number of seizures. In addition, hormonal treatment was also able to stabilize the mossy fibers sprouting process, showing the importance of these hormones in the development of the epilepsy in female rats. PMID:18760902

Valente, S G; Marques, R H; Baracat, E C; Cavalheiro, E A; Naffah-Mazzacoratti, M G; Amado, D

2008-08-29

205

Immunogenicity of the E1E2 proteins of hepatitis C virus expressed by recombinant adenoviruses  

Microsoft Academic Search

The E1 and E2 proteins of hepatitis C virus (HCV) are believed to be the viral envelope glycoproteins that are major candidate antigens for HCV vaccine development. We reported previously that the replication-competent recombinant adenovirus encoding core-E1-E2 genes of HCV (Ad\\/HCV) produces serologically reactive E1 and E2 proteins forming a heterodimer in substantial amounts. Here, we examined immunogenicity of the

Young Rim Seong; Seeyoung Choi; Jong-Seok Lim; Chan-Hee Lee; Chong-Kyo Lee; Dong-Soo Im

2001-01-01

206

Distinct and redundant functions of cyclin E1 and cyclin E2 in development and cancer  

Microsoft Academic Search

The highly conserved E-type cyclins are core components of the cell cycle machinery, facilitating the transition into S phase through activation of the cyclin dependent kinases, and assembly of pre-replication complexes on DNA. Cyclin E1 and cyclin E2 are assumed to be functionally redundant, as cyclin E1-\\/- E2-\\/- mice are embryonic lethal while cyclin E1-\\/- and E2-\\/- single knockout mice

C ELIZABETH Caldon; Elizabeth A Musgrove

2010-01-01

207

Signal sequences modulate the immunogenic performance of human hepatitis C virus E2 gene  

Microsoft Academic Search

Envelope protein E2 of human hepatitis C virus (HCV) is an attractive component of a prototype HCV vaccine. Delivered by DNA immunogens, E2 evokes specific immune response of Th1-type, failing to induce either considerable antibody production, or T-helper cell proliferation. We aimed at modulating the immunogenic performance of E2 gene by changing the mode of protein expression in eukaryotic cells.

Irina Sominskaya; Ekaterina Alekseeva; Dace Skrastina; Vladislav Mokhonov; Elizaveta Starodubova; Juris Jansons; Mikael Levi; Alexei Prilipov; Tatyana Kozlovska; Valeri Smirnov; Paul Pumpens; Maria G. Isaguliants

2006-01-01

208

Papillomavirus E2 proteins and the host BRD4 protein associate with transcriptionally active cellular chromatin.  

PubMed

The interaction of papillomavirus E2 proteins with cellular Brd4 protein is important for transcriptional regulation of viral genes and partitioning of viral genomes. Bovine papillomavirus type 1 (BPV-1) E2 binds cellular chromatin in complex with Brd4 in both mitotic and interphase cells. To identify specific sites of E2 interaction on cellular chromatin, a genome-wide chromatin immunoprecipitation-on-chip analysis was carried out using human promoter sequences. Both E2 and Brd4 were found bound to most transcriptionally active promoters in C33A cells. These promoters were also bound by RNA polymerase II and were modified by histone H3 acetylation and K4 trimethylation, all indicators of active transcription. E2 binding strongly correlated with Brd4 and RNA polymerase II occupancy and H3K4me3 modification at all human promoters, indicating that E2 bound to active promoters. E2 binding did not correlate with the presence of consensus E2 binding sites in the promoters. Furthermore, the mRNA levels of E2-bound cellular genes were not significantly changed by E2 expression. Thus, the papillomavirus E2 proteins bind to transcriptionally active cellular genes but do not change their activity. We propose that this may be a way for the virus to ensure that the viral genome is retained in transcriptionally active regions of the nucleus to escape silencing. Therefore, E2-mediated tethering of viral genomes to host chromatin has multiple roles: to partition the viral genome to daughter cells, to ensure that the genomes are retained in the nucleus, and to make certain that the genomes are retained in functionally active nuclear domains. PMID:19129460

Jang, Moon Kyoo; Kwon, Deukwoo; McBride, Alison A

2009-01-07

209

Sequence Determinants of E2-E6AP Binding Affinity and Specificity  

Microsoft Academic Search

The conjugation of ubiquitin to substrates requires a series of enzymatic reactions consisting of an activating enzyme (E1), conjugating enzymes (E2) and ligases (E3). Tagging the appropriate substrate with ubiquitin is achieved by specific E2–E3 and E3–substrate interactions. E6AP, a member of the HECT family of E3s, has been previously shown to bind and function with the E2s UbcH7 and

Ziad M. Eletr; Brian Kuhlman

2007-01-01

210

Localization of antigenic sites of the E2 glycoprotein of transmissible gastroenteritis coronavirus  

Microsoft Academic Search

Four antigenic sites of the E2 glycoprotein of transmis- sible gastroenteritis virus were defined by competitive radioimmunoassays ofmonoclonal antibodies (MAbs). Here, we describe the localization of these sites by testing the antigenicity of protein fragments and prokaryotic expression products of E2 gene fragments, and by sequencing of MAb-resistant (mar) mutants. Partial proteolysis of purified E2 protein allowed the isolation of

Isabel Correa; Fhtima Gebauer; M. J. Bullido; C. Sune; Marc F. D. Baay; Kornelisje A. Zwaagstra; Willem P. A. Posthumus; Johannes A. Lenstra; Luis Enjuanes

1990-01-01

211

Direct repression of the Mcl-1 promoter by E2F1  

Microsoft Academic Search

E2F1 induces apoptosis via both p53-dependent and p53-independent mechanisms. The direct targets in the p53-independent pathway remain enigmatic; however, the induction of this pathway does not require the transactivation domain of E2F1. Using cells that are defective in p53 activation, we show that E2F1 potently represses the expression of Mcl-1 – an anti-apoptotic Bcl-2 family member whose depletion results in

Rhonda Croxton; Yihong Ma; Lanxi Song; Eric B Haura; W Douglas Cress; D Cress

2002-01-01

212

Identification of Novel E2F1-Regulated Genes by Microarray  

Microsoft Academic Search

The E2F pathway has been proposed to regulate genes involved in the transition from quiescence into DNA synthesis. However, this hypothesis has not been rigorously tested on a genomic scale. Toward this end, we have infected quiescent mouse fibroblasts, which do not express E2F1, with an E2F1-expressing adenovirus and examined the expression of more than 6000 genes using high-density microarrays.

Yihong Ma; Rhonda Croxton; Ronnie L. Moorer; W. Douglas Cress

2002-01-01

213

E2F1 suppresses Wnt\\/?-catenin activity through transactivation of ?-catenin interacting protein ICAT  

Microsoft Academic Search

Deregulation of the pRb\\/E2F or Wnt\\/?-catenin pathway occurs frequently in human cancers, which is often associated with inappropriate cell proliferation. Although the oncogenic roles of pRb\\/E2F1 and Wnt\\/?-catenin pathways have been well studied, the functional interaction between the two pathways has only recently been characterized. In particular, E2F1 has been recently reported to negatively regulate Wnt\\/?-catenin activity in human colorectal

Z Wu; S Zheng; Z Li; J Tan; Q Yu

2011-01-01

214

Apoptotic and Growth-Promoting Activity of E2F Modulated by MDM2  

PubMed Central

E2F integrates and coordinates cell cycle progression with the transcription apparatus through its cyclical interactions with important regulators of cellular proliferation, such as pRb, cyclins, and cdk's. Physiological E2F is a heterodimeric transcription factor composed of an E2F and a DP family member, and while E2F proteins can stimulate proliferation, certain members of the family are known to be endowed with growth-inhibitory and tumor suppressor-like activity. We have investigated the product of the human mdm2 oncogene, hDM2, and report on its ability to regulate E2F-dependent apoptosis in a fashion that is independent of p53. hDM2 can prevent p53?/? cells from entering E2F-dependent apoptosis, an outcome that is dependent upon the presence of the DP subunit. Cells rescued from apoptosis possess lower levels of E2F subunits, although the rescued cells show an increase in DNA synthesis and possess enhanced viability that reflects cooperation between E2F-DP and hMD2. Furthermore, the regulation of E2F activity correlates with an hDM2-dependent effect on the intracellular distribution of DP-1, since hDM2 causes the nuclear accumulation of DP-1. The control of E2F by hDM2 therefore has certain parallels with the targeted degradation by MDM2 of p53. However, the domains in hDM2 required for the regulation of E2F activity can be distinguished from those necessary for p53 degradation, suggesting that control of E2F and p53 by hDM2 may be mechanistically distinct. These experiments define a new level of interplay between E2F and hDM2 whereby hDM2 has a profound impact on the physiological consequences of E2F activation. They suggest that the oncogenic properties of hDM2 may in part be mediated by an antiapoptotic activity that converts E2F from a negative to a positive regulator of cell cycle progression and thereby retains E2F at a level that contributes to a continual state of growth stimulation.

Loughran, Oonagh; La Thangue, Nicholas B.

2000-01-01

215

Distinct roles of E2F proteins in vascular smooth muscle cell proliferation and intimal hyperplasia.  

PubMed

Intimal hyperplasia (IH) and restenosis limit the long-term utility of bypass surgery and angioplasty due to pathological proliferation and migration of vascular smooth muscle cells (VSMCs) into the intima of treated vessels. Consequently, much attention has been focused on developing inhibitory agents that reduce this pathogenic process. The E2F transcription factors are key cell cycle regulators that play important roles in modulating cell proliferation and cell fate. Nonselective E2F inhibitors have thus been extensively evaluated for this purpose. Surprisingly, these E2F inhibitors have failed to reduce IH. These findings prompted us to evaluate the roles of different E2Fs during IH to determine how selective targeting of E2F isoforms impacts VSMC proliferation. Importantly, we show that E2F3 promotes proliferation of VSMCs leading to increased IH, whereas E2F4 inhibits this pathological response. Furthermore, we use RNA probes to show that selective inhibition of E2F3, not global inhibition of E2F activity, significantly reduces VSMC proliferation and limits IH in murine bypass grafts. PMID:17652516

Giangrande, Paloma H; Zhang, JianXin; Tanner, Alice; Eckhart, Andrea D; Rempel, Rachel E; Andrechek, Eran R; Layzer, Juliana M; Keys, Janelle R; Hagen, Per-Otto; Nevins, Joseph R; Koch, Walter J; Sullenger, Bruce A

2007-07-25

216

Distinct roles of E2F proteins in vascular smooth muscle cell proliferation and intimal hyperplasia  

PubMed Central

Intimal hyperplasia (IH) and restenosis limit the long-term utility of bypass surgery and angioplasty due to pathological proliferation and migration of vascular smooth muscle cells (VSMCs) into the intima of treated vessels. Consequently, much attention has been focused on developing inhibitory agents that reduce this pathogenic process. The E2F transcription factors are key cell cycle regulators that play important roles in modulating cell proliferation and cell fate. Nonselective E2F inhibitors have thus been extensively evaluated for this purpose. Surprisingly, these E2F inhibitors have failed to reduce IH. These findings prompted us to evaluate the roles of different E2Fs during IH to determine how selective targeting of E2F isoforms impacts VSMC proliferation. Importantly, we show that E2F3 promotes proliferation of VSMCs leading to increased IH, whereas E2F4 inhibits this pathological response. Furthermore, we use RNA probes to show that selective inhibition of E2F3, not global inhibition of E2F activity, significantly reduces VSMC proliferation and limits IH in murine bypass grafts.

Giangrande, Paloma H.; Zhang, JianXin; Tanner, Alice; Eckhart, Andrea D.; Rempel, Rachel E.; Andrechek, Eran R.; Layzer, Juliana M.; Keys, Janelle R.; Hagen, Per-Otto; Nevins, Joseph R.; Koch, Walter J.; Sullenger, Bruce A.

2007-01-01

217

E2F1-dependent methyl cap formation requires RNA pol II phosphorylation  

PubMed Central

Gene expression is a process integral to cell proliferation. The E2F family of transcription factors upregulates expression of transcripts whose products are essential for cell cycle progression. Here, we report that E2F1 promotes gene expression by an additional mechanism, that is, formation of the methyl cap on RNA pol II transcripts. The methyl cap is required for mRNA maturation, expression and stability. We demonstrate that E2F1 increases RNA pol II phosphorylation, which promotes recruitment of the methyl cap synthetic enzymes. Upregulation of RNA pol II phosphorylation is required for E2F1-dependent methyl cap formation.

Aregger, Michael; Cowling, Victoria H.

2012-01-01

218

Atypical E2fs Control Lymphangiogenesis through Transcriptional Regulation of Ccbe1 and Flt4  

PubMed Central

Lymphatic vessels are derived from venous endothelial cells and their formation is governed by the Vascular endothelial growth factor C (VegfC)/Vegf receptor 3 (Vegfr3; Flt4) signaling pathway. Recent studies show that Collagen and Calcium Binding EGF domains 1 protein (Ccbe1) enhances VegfC-dependent lymphangiogenesis. Both Ccbe1 and Flt4 have been shown to be indispensable for lymphangiogenesis. However, how these essential players are transcriptionally regulated remains poorly understood. In the case of angiogenesis, atypical E2fs (E2f7 and E2f8) however have been recently shown to function as transcriptional activators for VegfA. Using a genome-wide approach we here identified both CCBE1 and FLT4 as direct targets of atypical E2Fs. E2F7/8 directly bind and stimulate the CCBE1 promoter, while recruitment of E2F7/8 inhibits the FLT4 promoter. Importantly, inactivation of e2f7/8 in zebrafish impaired venous sprouting and lymphangiogenesis with reduced ccbe1 expression and increased flt4 expression. Remarkably, over-expression of e2f7/8 rescued Ccbe1- and Flt4-dependent lymphangiogenesis phenotypes. Together these results identified E2f7/8 as novel in vivo transcriptional regulators of Ccbe1 and Flt4, both essential genes for venous sprouting and lymphangiogenesis.

Weijts, Bart G. M. W.; van Impel, Andreas; Schulte-Merker, Stefan; de Bruin, Alain

2013-01-01

219

Regulation of E2F1 function by the nuclear corepressor KAP1.  

PubMed

KAP1 is a nuclear corepressor with conserved domains for RING finger, B boxes, leucine zipper alpha helical coiled-coil region, plant homeo domain finger, and bromo domain. The plant homeo domain finger and bromo domain of KAP1 cooperatively function as a transcription repression domain by recruiting the histone deacetylase complex NuRD and histone H3 lysine 9-specific methyltransferase SETDB1. Here we report that KAP1 binds the E2F1 transcription factor in a retinoblastoma protein (pRb)-independent fashion and inhibits E2F1 activity. KAP1 stimulates formation of E2F1-HDAC1 complex and inhibits E2F1 acetylation. Ectopic expression of KAP1 represses E2F1 transcription and apoptosis functions independent of pRb. Depletion of endogenous KAP1 in pRb-deficient Saos2 cells by RNA interference increases E2F1 acetylation level, stimulates E2F1 transcriptional activity, and sensitizes apoptosis response to DNA damage. Therefore, KAP1 contributes to the negative regulation of E2F1 and may serve as a partial backup to prevent E2F1-mediated apoptosis in the absence of pRb. PMID:17704056

Wang, Chuangui; Rauscher, Frank J; Cress, W Douglas; Chen, Jiandong

2007-08-17

220

Modification of Papillomavirus E2 proteins by the Small Ubiquitin-like Modifier Family Members (SUMOs)  

PubMed Central

Papillomavirus E2 proteins are critical regulatory proteins that function in replication, genome segregation, and viral transcription, including control of expression of the viral oncogenes, E6 and E7. Sumoylation is a post-translational modification that has been shown to target and modulate the function of many transcription factors, and we now demonstrate that E2 proteins are sumoylated. Both bovine and human papillomavirus E2 proteins bind to the SUMO conjugation enzyme, Ubc9, and using in vitro and E. coli sumoylation systems, these E2 proteins were readily modified by SUMO proteins. In vivo experiments further confirmed that E2 can be sumoylated by SUMO1, SUMO2, or SUMO3. Mapping studies identified lysine 292 as the principal residue for covalent conjugation of SUMO to HPV16 E2, and a lysine 292 to arginine mutant showed defects for both transcriptional activation and repression. The expression levels, intracellular localization, and the DNA-binding activity of HPV16 E2 were unchanged by this K292R mutation, suggesting that the transcriptional defect reflects a functional contribution by sumoylation at this residue. This study provides evidence that sumoylation has a role in the regulation of papillomavirus E2, and identifies a new mechanism for the modulation of E2 function at the post-translational level.

Wu, Yu-Chieh; Roark, Ashley A.; Bian, Xue-Lin; Wilson, Van G.

2008-01-01

221

Arginine Methylation-Dependent Reader-Writer Interplay Governs Growth Control by E2F-1.  

PubMed

The mechanisms that underlie and dictate the different biological outcomes of E2F-1 activity have yet to be elucidated. We describe the residue-specific methylation of E2F-1 by the asymmetric dimethylating protein arginine methyltransferase 1 (PRMT1) and symmetric dimethylating PRMT5 and relate the marks to different functional consequences of E2F-1 activity. Methylation by PRMT1 hinders methylation by PRMT5, which augments E2F-1-dependent apoptosis, whereas PRMT5-dependent methylation favors proliferation by antagonizing methylation by PRMT1. The ability of E2F-1 to prompt apoptosis in DNA damaged cells coincides with enhanced PRMT1 methylation. In contrast, cyclin A binding to E2F-1 impedes PRMT1 methylation and augments PRMT5 methylation, thus ensuring that E2F-1 is locked into its cell-cycle progression mode. The Tudor domain protein p100-TSN reads the symmetric methylation mark, and binding of p100-TSN downregulates E2F-1 apoptotic activity. Our results define an exquisite level of precision in the reader-writer interplay that governs the biological outcome of E2F-1 activity. PMID:24076217

Zheng, Shunsheng; Moehlenbrink, Jutta; Lu, Yi-Chien; Zalmas, Lykourgos-Panagiotis; Sagum, Cari A; Carr, Simon; McGouran, Joanna F; Alexander, Leila; Fedorov, Oleg; Munro, Shonagh; Kessler, Benedikt; Bedford, Mark T; Yu, Qiang; La Thangue, Nicholas B

2013-09-26

222

Functional impact of colorectal cancer-associated mutations in the transcription factor E2F4.  

PubMed

The transcription factor E2F4 plays a critical role in cell cycle progression of normal and cancerous intestinal epithelial cells. Contrary to other E2Fs, the coding region of the E2F4 gene contains a longer spacer segment of a CAG trinucleotide repeat sequence encoding 13 consecutive serine residues, which is highly vulnerable to frameshift mutations in situations of genetic instability. Mutations in this region of the E2F4 gene have been observed in colorectal tumors with microsatellite instability. However, the effect of these changes on its function in colorectal cancer cells is currently unknown. We generated E2F4(CAG)12 and E2F4(CAG)14 mutants and compared their activity to the E2F4 wild-type, E2F4(CAG)13. Luciferase assays with the thymidine kinase-luc reporter gene revealed that the mutants were more transcriptionally active than wild-type E2F4. The mechanism of increased activity of E2F4 was primarily related to protein stability, due to a significantly enhanced half-life of E2F4 mutants comparatively to that of wild-type E2F4. However, the association with the pocket protein p130/RBL2 did not account for this increased protein stability. Sequencing analysis of the endogenous E2F4 gene in a series of colorectal cancer cell lines showed that the microsatellite-unstable cell line SW48 exhibited a serine deletion in this gene. Accordingly, E2F4 half-life was much more elevated in SW48 cells in comparison to Caco-2/15, a microsatellite-stable cell line. Notably, in soft-agar assays, both mutants more potently increased anchorage-independent growth in comparison to wild-type E2F4. In conclusion, our data demonstrate that cancer-associated E2F4 mutations enhance the capacity of colorectal cancer cells to grow without anchorage, thereby contributing to tumor progression. PMID:24100580

Paquin, Marie-Christine; Leblanc, Caroline; Lemieux, Etienne; Bian, Benjamin; Rivard, Nathalie

2013-10-08

223

Atypical E2fs Control Lymphangiogenesis through Transcriptional Regulation of Ccbe1 and Flt4.  

PubMed

Lymphatic vessels are derived from venous endothelial cells and their formation is governed by the Vascular endothelial growth factor C (VegfC)/Vegf receptor 3 (Vegfr3; Flt4) signaling pathway. Recent studies show that Collagen and Calcium Binding EGF domains 1 protein (Ccbe1) enhances VegfC-dependent lymphangiogenesis. Both Ccbe1 and Flt4 have been shown to be indispensable for lymphangiogenesis. However, how these essential players are transcriptionally regulated remains poorly understood. In the case of angiogenesis, atypical E2fs (E2f7 and E2f8) however have been recently shown to function as transcriptional activators for VegfA. Using a genome-wide approach we here identified both CCBE1 and FLT4 as direct targets of atypical E2Fs. E2F7/8 directly bind and stimulate the CCBE1 promoter, while recruitment of E2F7/8 inhibits the FLT4 promoter. Importantly, inactivation of e2f7/8 in zebrafish impaired venous sprouting and lymphangiogenesis with reduced ccbe1 expression and increased flt4 expression. Remarkably, over-expression of e2f7/8 rescued Ccbe1- and Flt4-dependent lymphangiogenesis phenotypes. Together these results identified E2f7/8 as novel in vivo transcriptional regulators of Ccbe1 and Flt4, both essential genes for venous sprouting and lymphangiogenesis. PMID:24069224

Weijts, Bart G M W; van Impel, Andreas; Schulte-Merker, Stefan; de Bruin, Alain

2013-09-12

224

The SNF2-like helicase HELLS mediates E2F3-dependent transcription and cellular transformation.  

PubMed

The activating E2F-transcription factors are best known for their dependence on the Retinoblastoma protein and their role in cellular proliferation. E2F3 is uniquely amplified in specific human tumours where its expression is inversely correlated with the survival of patients. Here, E2F3B interaction partners were identified by mass spectrometric analysis. We show that the SNF2-like helicase HELLS interacts with E2F3A in vivo and cooperates with its oncogenic functions. Depletion of HELLS severely perturbs the induction of E2F-target genes, hinders cell-cycle re-entry and growth. Using chromatin immmunoprecipitation coupled to sequencing, we identified genome-wide targets of HELLS and E2F3A/B. HELLS binds promoters of active genes, including the trithorax-related MLL1, and co-regulates E2F3-dependent genes. Strikingly, just as E2F3, HELLS is overexpressed in human tumours including prostate cancer, indicating that either factor may contribute to the malignant progression of tumours. Our work reveals that HELLS is important for E2F3 in tumour cell proliferation. PMID:22157815

von Eyss, Björn; Maaskola, Jonas; Memczak, Sebastian; Möllmann, Katharina; Schuetz, Anja; Loddenkemper, Christoph; Tanh, Mai-Dinh; Otto, Albrecht; Muegge, Kathrin; Heinemann, Udo; Rajewsky, Nikolaus; Ziebold, Ulrike

2011-12-13

225

Characterization of the nuclear localization signal of high risk HPV16 E2 protein  

SciTech Connect

The E2 protein of high risk human papillomavirus type 16 (HPV16) contains an amino-terminal (N) domain, a hinge (H) region and a carboxyl-terminal (C) DNA-binding domain. Using enhanced green fluorescent protein (EGFP) fusions with full length E2 and E2 domains in transfection assays in HeLa cells, we found that the C domain is responsible for the nuclear localization of E2 in vivo, whereas the N and H domains do not contain additional nuclear localization signals (NLSs). Deletion analysis of EGFP-E2 and EGFP-cE2 determined that the C domain contains an {alpha} helix cNLS that overlaps with the DNA-binding region. Mutational analysis revealed that the arginine and lysine residues in this cNLS are essential for nuclear localization of HPV16 E2. Interestingly, these basic amino acid residues are well conserved among the E2 proteins of BPV-1 and some high risk HPV types but not in the low risk HPV types, suggesting that there are differences between the NLSs and corresponding nuclear import pathways between these E2 proteins.

Klucevsek, Kristin [Biology Department, Boston College, Higgins Hall, room 578, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 (United States); Wertz, Mary [Biology Department, Boston College, Higgins Hall, room 578, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 (United States); Lucchi, John [Biology Department, Boston College, Higgins Hall, room 578, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 (United States); Leszczynski, Anna [Biology Department, Boston College, Higgins Hall, room 578, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 (United States); Moroianu, Junona [Biology Department, Boston College, Higgins Hall, room 578, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 (United States)]. E-mail: moroianu@bc.edu

2007-03-30

226

E2F1 Expression Predicts Outcome in Korean Women Who Undergo Surgery for Breast Carcinoma  

Microsoft Academic Search

Background  The transcriptional factors E2F1 and E2F2 have been reported to be associated with improved chemosensitivity in various cancers.\\u000a We aimed to investigate whether E2F1 and E2F2 can be used as predictors of chemosensitivity in hormone-receptor-negative breast\\u000a cancers (HRNBCs), which are common in Korean women.\\u000a \\u000a \\u000a \\u000a Methods  A total of 183 patients with primary breast cancer who had undergone surgical resection were evaluated

Mi Jung Kwon; Eun Sook Nam; Seong Jin Cho; Hye Rim Park; Hyung Sik Shin; Jun Ho Park; Chan Heun Park; Won Jae Lee

2010-01-01

227

Combined effects of E2F1 and E2F2 polymorphisms on risk and early onset of squamous cell carcinoma of the head and neck  

PubMed Central

Deregulated expression of most members of the E2F family has been detected in many human cancers. We examined the association of common single nucleotide polymorphisms (SNPs) of E2F1 and E2F2 with risk of squamous cell carcinoma of the head and neck (SCCHN) in 1,096 SCCHN patients and 1,090 cancer-free controls. We genotyped ten selected SNPs in E2F1 and E2F2, including those at the near 5? UTR, miRNA binding sites at the near 3? UTR and tagSNPs according to bioinfotmatics analysis. Although none of the selected SNPs alone was significantly associated with risk of SCCHN, there was a statistically significantly increased risk of SCCHN associated with the combined risk genotypes (i.e. rs3213182 AA, rs3213183 GG, rs3213180 GG, rs321318121 GG, rs2742976 GT+TT, rs6667575 GA+AA, rs3218203 CC, rs3218148 AA, rs3218211 CC, rs3218123 GT+TT). Compared with those with 0–4 risk genotypes, an increased risk was observed for those who carried 5–8 risk genotypes (adjusted OR = 1.04; 95% CI = 0.86–1.26) and 9–10 risk genotypes (adjusted OR = 1.62; 95% CI = 1.14–2.30) in a dose-response manner (P = 0.045). Furthermore, the joint effect was more pronounced among patients with oropharyngeal cancer, younger adults (?57 years old), men, non-smokers, non-drinkers, and individuals with family history of cancer first-degree relatives. Additionally, we also observed that those with 5–10 risk genotypes had an earlier SCCHN onset than those with 0–4 risk genotypes, particularly for non-smokers and/or non-drinkers. We concluded that E2F1 and E2F2 genetic variants may jointly play important roles in head and neck carcinogenesis.

Lu, Meixia; Liu, Zhensheng; Yu, Hongping; Wang, Li-E; Li, Guojun; Sturgis, Erich M.; Johnson, David G.; Wei, Qingyi

2012-01-01

228

E2 Conjugating Enzyme Selectivity and Requirements for Function of the E3 Ubiquitin Ligase CHIP*  

PubMed Central

The transfer of ubiquitin (Ub) to a substrate protein requires a cascade of E1 activating, E2 conjugating, and E3 ligating enzymes. E3 Ub ligases containing U-box and RING domains bind both E2?Ub conjugates and substrates to facilitate transfer of the Ub molecule. Although the overall mode of action of E3 ligases is well established, many of the mechanistic details that determine the outcome of ubiquitination are poorly understood. CHIP (carboxyl terminus of Hsc70-interacting protein) is a U-box E3 ligase that serves as a co-chaperone to heat shock proteins and is critical for the regulation of unfolded proteins in the cytosol. We have performed a systematic analysis of the interactions of CHIP with E2 conjugating enzymes and found that only a subset bind and function. Moreover, some E2 enzymes function in pairs to create products that neither create individually. Characterization of the products of these reactions showed that different E2 enzymes produce different ubiquitination products, i.e. that E2 determines the outcome of Ub transfer. Site-directed mutagenesis on the E2 enzymes Ube2D1 and Ube2L3 (UbcH5a and UbcH7) established that an SPA motif in loop 7 of E2 is required for binding to CHIP but is not sufficient for activation of the E2?Ub conjugate and consequent ubiquitination activity. These data support the proposal that the E2 SPA motif provides specificity for binding to CHIP, whereas activation of the E2?Ub conjugate is derived from other molecular determinants.

Soss, Sarah E.; Yue, Yuanyuan; Dhe-Paganon, Sirano; Chazin, Walter J.

2011-01-01

229

E2 conjugating enzyme selectivity and requirements for function of the E3 ubiquitin ligase CHIP.  

PubMed

The transfer of ubiquitin (Ub) to a substrate protein requires a cascade of E1 activating, E2 conjugating, and E3 ligating enzymes. E3 Ub ligases containing U-box and RING domains bind both E2?Ub conjugates and substrates to facilitate transfer of the Ub molecule. Although the overall mode of action of E3 ligases is well established, many of the mechanistic details that determine the outcome of ubiquitination are poorly understood. CHIP (carboxyl terminus of Hsc70-interacting protein) is a U-box E3 ligase that serves as a co-chaperone to heat shock proteins and is critical for the regulation of unfolded proteins in the cytosol. We have performed a systematic analysis of the interactions of CHIP with E2 conjugating enzymes and found that only a subset bind and function. Moreover, some E2 enzymes function in pairs to create products that neither create individually. Characterization of the products of these reactions showed that different E2 enzymes produce different ubiquitination products, i.e. that E2 determines the outcome of Ub transfer. Site-directed mutagenesis on the E2 enzymes Ube2D1 and Ube2L3 (UbcH5a and UbcH7) established that an SPA motif in loop 7 of E2 is required for binding to CHIP but is not sufficient for activation of the E2?Ub conjugate and consequent ubiquitination activity. These data support the proposal that the E2 SPA motif provides specificity for binding to CHIP, whereas activation of the E2?Ub conjugate is derived from other molecular determinants. PMID:21518764

Soss, Sarah E; Yue, Yuanyuan; Dhe-Paganon, Sirano; Chazin, Walter J

2011-04-25

230

In Vivo Regulation of E2F1 by Polycomb Group Genes in Drosophila  

PubMed Central

The E2F transcription factors are important regulators of the cell cycle whose function is commonly misregulated in cancer. To identify novel regulators of E2F1 activity in vivo, we used Drosophila to conduct genetic screens. For this, we generated transgenic lines that allow the tissue-specific depletion of dE2F1 by RNAi. Expression of these transgenes using Gal4 drivers in the eyes and wings generated reliable and modifiable phenotypes. We then conducted genetic screens testing the capacity of Exelixis deficiencies to modify these E2F1-RNAi phenotypes. From these screens, we identified mutant alleles of Suppressor of zeste 2 [Su(z)2] and multiple Polycomb group genes as strong suppressors of the E2F1-RNA interference phenotypes. In validation of our genetic data, we find that depleting Su(z)2 in cultured Drosophila cells restores the cell-proliferation defects caused by reduction of dE2F1 by elevating the level of dE2f1. Furthermore, analyses of methylation status of histone H3 lysine 27 (H3K27me) from the published modENCODE data sets suggest that the genomic regions harboring dE2f1 gene and certain dE2f1 target genes display H3K27me during development and in several Drosophila cell lines. These in vivo observations suggest that the Polycomb group may regulate cell proliferation by repressing the transcription of dE2f1 and certain dE2F1 target genes. This mechanism may play an important role in coordinating cellular differentiation and proliferation during Drosophila development.

Ji, Jun-Yuan; Miles, Wayne O.; Korenjak, Michael; Zheng, Yani; Dyson, Nicholas J.

2012-01-01

231

Podophyllotoxin directly binds a hinge domain in E2 of HPV and inhibits an E2/E7 interaction in vitro.  

PubMed

Podophyllotoxin (PT), a strong cytotoxic agent from berberidaceae, has been known to inhibit tubulin polymerization. Although PT has been used for developing anticancer drugs as one of seed compounds, clinical treatment by itself has been unsuccessful because of the side effects, except one example in the treatments of warts. In this study, we screened peptides binding to PT with T7 phage display clonings in order to obtain more information about molecular mechanism of the action. A selected phage clone has a specific amino acid sequence to be SVPSRRRPDGRTHRSSRG. A homology search by protein database BLAST showed that this sequence had a similarity to a hinge domain (HD) of E2 protein in human papillomavirus (HPV) type 1a which is known to cause plantar warts. Surface plasmon resonance (SPR) analysis showed that PT bound to a recombinant HPV 1a E2 protein giving a K(D)=24.1microM which has compared with those of other domains of E2 protein. Also we demonstrated whether PT inhibited HD interaction or not. E7 protein of HPV has been known to be an oncoprotein and was reported to interact with HD of E2 protein. We demonstrated that an E2/E7 interaction was inhibited by the addition of PT in this report. And we showed the bindings of PT to other types of HPV. Our results suggest that PT is potential as a tool for clarifying the molecular mechanism of HPV. PMID:18396405

Saitoh, Takeki; Kuramochi, Kouji; Imai, Takahiko; Takata, Kei-ichi; Takehara, Masahide; Kobayashi, Susumu; Sakaguchi, Kengo; Sugawara, Fumio

2008-03-25

232

Allosteric Activation of E2-RING Finger-Mediated Ubiquitylation by a Structurally Defined Specific E2-Binding Region of gp78  

SciTech Connect

The activity of RING finger ubiquitin ligases (E3) is dependent on their ability to facilitate transfer of ubiquitin from ubiquitin-conjugating enzymes (E2) to substrates. The G2BR domain within the E3 gp78 binds selectively and with high affinity to the E2 Ube2g2. Through structural and functional analyses, we determine that this occurs on a region of Ube2g2 distinct from binding sites for ubiquitin-activating enzyme (E1) and RING fingers. Binding to the G2BR results in conformational changes in Ube2g2 that affect ubiquitin loading. The Ube2g2:G2BR interaction also causes an 50-fold increase in affinity between the E2 and RING finger. This results in markedly increased ubiquitylation by Ube2g2 and the gp78 RING finger. The significance of this G2BR effect is underscored by enhanced ubiquitylation observed when Ube2g2 is paired with other RING finger E3s. These findings uncover a mechanism whereby allosteric effects on an E2 enhance E2-RING finger interactions and, consequently, ubiquitylation.

Das, Ranabir; Mariano, Jennifer; Tsai, Yien Che; Kalathur, Ravi C.; Kostova, Zlatka; Li, Jess; Tarasov, Sergey G.; McFeeters, Robert L.; Altieri, Amanda S.; Ji, Xinhua; Byrd, R. Andrew; Weissman, Allan M.; (NCI)

2010-11-12

233

Functional characterization of the Sindbis virus E2 glycoprotein by transposon linker-insertion mutagenesis  

SciTech Connect

The glycoprotein envelope of alphaviruses consists of two proteins, E1 and E2. E1 is responsible for fusion and E2 is responsible for receptor binding. An atomic structure is available for E1, but one for E2 has not been reported. In this study, transposon linker-insertion mutagenesis was used to probe the function of different domains of E2. A library of mutants, containing 19 amino acid insertions in the E2 glycoprotein sequence of the prototype alphavirus, Sindbis virus (SINV), was generated. Fifty-seven independent E2 insertions were characterized, of which more than half (67%) gave rise to viable virus. The wild-type-like mutants identify regions that accommodate insertions without perturbing virus production and can be used to insert targeting moieties to direct SINV to specific receptors. The defective and lethal mutants give insight into regions of E2 important for protein stability, transport to the cell membrane, E1-E2 contacts, and receptor binding.

Navaratnarajah, Chanakha K. [Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054 (United States); Kuhn, Richard J. [Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054 (United States)]. E-mail: kuhnr@purdue.edu

2007-06-20

234

VirE2-dependent pores for ssDNA transfer across artificial and cell membranes.  

PubMed

The transfer of single-stranded (ss) T-DNA from soil bacteria of the genus Agrobacterium with the help of the VirE2 protein, which possibly mediates the delivery of ss-T-DNA across the cell membrane, was demonstrated earlier, but how VirE2 participates in ssDNA transfer across artificial and natural membranes is not known. Using computational methods, we reconstructed model structures composed of two and four VirE2 proteins and showed by the MOLE program the formation of pores with channel diameters of 1.2-1.6 and 1.4-4.6 nm in a model structure formed from two and four VirE2 molecules, respectively. Using light scattering, we recorded the size distribution for recombinant VirE2-dependent complexes in aqueous solutions and found that VirE2 in a buffer solution is present as a complex made up of two or more proteins. We revealed single, long-lived jumps in voltage-dependent membrane conductance during coincubation of planar black membranes with the VirE2 protein. On the addition of VirE2 and FAM-labeled oligonucleotides to HeLa cells, the fluorescence intensity for the cells increased by 56% as compared to that for cells incubated only with oligonucleotides. PMID:22809344

Volokhina, Irina; Gusev, Yury; Mazilov, Svyatoslav; Chumakov, Mikhail

2012-04-01

235

A human ubiquitin conjugating enzyme (E2)-HECT E3 ligase structure-function screen.  

PubMed

Here we describe a systematic structure-function analysis of the human ubiquitin (Ub) E2 conjugating proteins, consisting of the determination of 15 new high-resolution three-dimensional structures of E2 catalytic domains, and autoubiquitylation assays for 26 Ub-loading E2s screened against a panel of nine different HECT (homologous to E6-AP carboxyl terminus) E3 ligase domains. Integration of our structural and biochemical data revealed several E2 surface properties associated with Ub chain building activity; (1) net positive or neutral E2 charge, (2) an "acidic trough" located near the catalytic Cys, surrounded by an extensive basic region, and (3) similarity to the previously described HECT binding signature in UBE2L3 (UbcH7). Mass spectrometry was used to characterize the autoubiquitylation products of a number of functional E2-HECT pairs, and demonstrated that HECT domains from different subfamilies catalyze the formation of very different types of Ub chains, largely independent of the E2 in the reaction. Our data set represents the first comprehensive analysis of E2-HECT E3 interactions, and thus provides a framework for better understanding the molecular mechanisms of ubiquitylation. PMID:22496338

Sheng, Yi; Hong, Jenny H; Doherty, Ryan; Srikumar, Tharan; Shloush, Jonathan; Avvakumov, George V; Walker, John R; Xue, Sheng; Neculai, Dante; Wan, Janet W; Kim, Sung K; Arrowsmith, Cheryl H; Raught, Brian; Dhe-Paganon, Sirano

2012-04-10

236

A Human Ubiquitin Conjugating Enzyme (E2)-HECT E3 Ligase Structure-function Screen*  

PubMed Central

Here we describe a systematic structure-function analysis of the human ubiquitin (Ub) E2 conjugating proteins, consisting of the determination of 15 new high-resolution three-dimensional structures of E2 catalytic domains, and autoubiquitylation assays for 26 Ub-loading E2s screened against a panel of nine different HECT (homologous to E6-AP carboxyl terminus) E3 ligase domains. Integration of our structural and biochemical data revealed several E2 surface properties associated with Ub chain building activity; (1) net positive or neutral E2 charge, (2) an “acidic trough” located near the catalytic Cys, surrounded by an extensive basic region, and (3) similarity to the previously described HECT binding signature in UBE2L3 (UbcH7). Mass spectrometry was used to characterize the autoubiquitylation products of a number of functional E2-HECT pairs, and demonstrated that HECT domains from different subfamilies catalyze the formation of very different types of Ub chains, largely independent of the E2 in the reaction. Our data set represents the first comprehensive analysis of E2-HECT E3 interactions, and thus provides a framework for better understanding the molecular mechanisms of ubiquitylation.

Sheng, Yi; Hong, Jenny H.; Doherty, Ryan; Srikumar, Tharan; Shloush, Jonathan; Avvakumov, George V.; Walker, John R.; Xue, Sheng; Neculai, Dante; Wan, Janet W.; Kim, Sung K.; Arrowsmith, Cheryl H.; Raught, Brian; Dhe-Paganon, Sirano

2012-01-01

237

Highly protective E2–CSFV vaccine candidate produced in the mammary gland of adenoviral transduced goats  

Microsoft Academic Search

Classical swine fever virus is the etiological agent of the most economically important highly contagious disease of swine worldwide. E2 is the major envelope glycoprotein present as a homodimer on the outer surface of the virus and represents an important target for the induction of neutralizing immune response against the viral infection. The E2 extracellular domain was expressed in the

Jorge R. Toledo; Oliberto Sánchez; Raquel Montesino; Omar Farnos; Maria P. Rodríguez; Pastor Alfonso; Nayrobis Oramas; Elsa Rodríguez; Elaine Santana; Ernesto Vega; Llilianne Ganges; Maria T. Frias; José Cremata; Maritza Barrera

2008-01-01

238

Ectopic E2F expression induces S phase and apoptosis in Drosophila imaginal discs.  

PubMed

Previous experiments suggest that a key event in the commitment of cultured mammalian cells to entering S phase is a rise in activity of the transcription factor E2F. In this report, we study the role of Drosophila E2F in imaginal disc cells in vivo, by examining the distribution of the endogenous protein and studying the consequences of ectopic E2F expression. First, we find that endogenous E217 falls from high to very low levels as cells initiate DNA synthesis during a developmentally regulated G1-S-transition in the eye disc. Second, we find that ectopic E2F expression drives many otherwise quiescent cells to enter S phase. Subsequently, cells throughout the discs express reaper (a regulator of apoptosis) and then die. Third, we find that ectopic E2F expression during S phase in normally cycling cells blocks their re-entry into S phase in the following cell cycle. Although we do not know the fate of these cells, we suspect that ultimately they are killed by ectopic E2F. Taken together, our results show that an elevation in the level of E2F is sufficient to induce imaginal disc cells to enter S phase. Furthermore, they suggest that the downregulation of E2F upon entry into S phase may be essential to prevent the induction of apoptosis. PMID:8647438

Asano, M; Nevins, J R; Wharton, R P

1996-06-01

239

Resolvin E2 formation and impact in inflammation-resolution1  

PubMed Central

Acute inflammation and its resolution are essential processes for tissue protection and homeostasis. In this context, specialized pro-resolving mediators derived from polyunsaturated fatty acids are of interest. Here, we report that resolvin E2 (RvE2) from eicosapentaenoic acid is endogenously produced during self-limited murine peritonitis in both the initiation and resolution phases. RvE2 (1–10 nM) carries potent leukocyte-directed actions that include 1) regulating chemotaxis of human neutrophils, and 2) enhancing phagocytosis and anti-inflammatory cytokine production. These actions appear to be mediated by leukocyte G-protein coupled receptors as preparation of labeled RvE2 gave direct evidence for specific binding of radiolabeled RvE2 to neutrophils (Kd 24.7 ± 10.1 nM) and RvE1 activation of recombinant GPCRs was assessed. In addition to the murine inflammatory milieu, RvE2 was also identified in plasma from healthy human subjects. RvE2 rapidly downregulated surface expression of human leukocyte integrins in whole blood and dampened responses to platelet-activating factor. Together, these results indicate that RvE2 can stimulate host-protective actions throughout initiation and resolution in the innate inflammatory responses.

Oh, Sungwhan F.; Dona, Maria; Fredman, Gabrielle; Krishnamoorthy, Sriram; Irimia, Daniel; Serhan, Charles N.

2012-01-01

240

The E2F6 repressor activates gene expression in myocardium resulting in dilated cardiomyopathy.  

PubMed

The E2F/Rb pathway regulates cardiac growth and development and holds great potential as a therapeutic target. The E2F6 repressor is a unique E2F member that acts independently of pocket proteins. Forced expression of E2F6 in mouse myocardium induced heart failure and mortality, with severity of symptoms correlating to E2F6 levels. Echocardiography demonstrated a 37% increase (P<0.05) in left ventricular end-diastolic diameter and reduced ejection fraction (<40%, P<0.05) in young transgenic (Tg) mice. Microarray and qPCR analysis revealed a paradoxical increase in E2F-responsive genes, which regulate the cell cycle, without changes in cardiomyocyte cell number or size in Tg mice. Young adult Tg mice displayed a 75% (P<0.01) decrease in gap junction protein connexin-43, resulting in abnormal electrocardiogram including a 24% (P<0.05) increase in PR interval. Further, mir-206, which targets connexin-43, was up-regulated 10-fold (P<0.05) in Tg myocardium. The mitogen-activated protein kinase pathway, which regulates the levels of miR-206 and connexin-43, was activated in Tg hearts. Thus, deregulated E2F6 levels evoked abnormal gene expression at transcriptional and post-transcriptional levels, leading to cardiac remodeling and dilated cardiomyopathy. The data highlight an unprecedented role for the strict regulation of the E2F pathway in normal postnatal cardiac function. PMID:22403008

Westendorp, Bart; Major, Jennifer L; Nader, Moni; Salih, Maysoon; Leenen, Frans H H; Tuana, Balwant S

2012-03-07

241

Cell cycle-related transformation of the E2F4-p130 repressor complex  

SciTech Connect

During G0 phase the p130, member of the pRb tumor suppressor protein family, forms a repressor complex with E2F4 which is inactivated in G1/S by hyperphosphorylation of the p130. The role of p130 after G1/S remains poorly investigated. We found that in nuclear extracts of T98G cells, the p130-E2F4-DNA (pp-E2F4) complex does not dissociate at G1/S transition, but instead reverts to the p130-E2F4-cyclin E/A-cdk2 (cyc/cdk-pp-E2F4) complex, which is detected in S and G2/M phases of the cell cycle. Hyperphosphorylation of the p130 at G1/S transition is associated with a decrease of its total amount; however, this protein is still detected during the rest of the cell cycle, and it is increasingly hyperphosphorylated in the cytosol, but continuously dephosphorylated in the nucleus. Both nuclear and cytosol cell fractions in T98G cells contain a hyperphosphorylated form of p130 in complex with E2F4 at S and G2/M cell cycle phases. In contrast to T98G cells, transformation of the p130 containing cyc/cdk-pp-E2F4 complex into the p130-pp-E2F4 repressor does not occur in HeLa cells under growth restriction conditions.

Popov, Boris [Institute of Cytology, Russian Academy of Sciences, 4, Tikhoretsky Ave., St. Petersburg 194064 (Russian Federation) and Department of Pediatrics, Children's Hospital, Ohio State University, Columbus, OH 43205-2696 (United States)]. E-mail: popov_478@hotmail.com; Chang, L.-S. [Department of Pediatrics, Children's Hospital, Ohio State University, Columbus, OH 43205-2696 (United States); Serikov, Vladimir [Institute of Cytology, Russian Academy of Sciences, 4, Tikhoretsky Ave., St. Petersburg 194064 (Russian Federation); Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609-1673 (United States)

2005-10-28

242

Characterization of a new chimeric marker vaccine candidate with a mutated antigenic E2-epitope.  

PubMed

A new chimeric pestivirus "CP7_E1E2alf_TLA", based on the infectious cDNA of bovine viral diarrhea virus (BVDV) strain CP7, was constructed. The substitution of BVDV E1 and E2 with the respective proteins of classical swine fever (CSF) strain Alfort 187 allows an optimal heterodimerization of E1 and E2 in the chimeric virus, which is beneficial for efficient and authentic virus assembly and growth. In addition, for implementation of E2-based marker diagnostics, the previously described antigenic CSFV-specific TAVSPTTLR epitope was exchanged with the corresponding E2-epitope of BVDV strain CP7. Recombinant virus CP7_E1E2alf_TLA displayed a growth defect, and was not reacting with monoclonal antibodies used in commercial E2 antibody blocking ELISAs. Therefore, efficacy as well as marker properties of CP7_E1E2alf_TLA were investigated in an animal experiment with both a high dose and a low dose vaccine preparation. All CP7_E1E2alf_TLA-vaccinated animals seroconverted until day 28 post-vaccination with neutralizing antibodies. Furthermore, at the day of challenge infection CP7_E1E2alf_TLA-immunized animals showed distinct lower ELISA values in a commercial CSFV E2 antibody test in comparison to the C-strain vaccinated controls. However, E2-ELISA reactivity as well as neutralizing titers were directly connected to the dosage used for vaccination, and only the low dose group had E2-ELISA values below threshold until challenge infection. Following challenge infection with highly virulent CSFV strain Koslov, all vaccinees were protected, however, short-term fever episodes and very limited CSFV genome detection with very low copy numbers could be observed. In conclusion, manipulation of the TAVSPTTLR-epitope within the tested chimeric virus resulted in an slightly reduced efficacy, but the E2 marker properties unexpectedly did not allow a clear differentiation of infected from vaccinated animals in some cases. PMID:19892497

Reimann, Ilona; Depner, Klaus; Utke, Katrin; Leifer, Immanuel; Lange, Elke; Beer, Martin

2009-10-09

243

Emerging roles of E2Fs in cancer: an exit from cell cycle control  

PubMed Central

Mutations of the retinoblastoma tumour suppressor gene (RB1) or components regulating the RB pathway have been identified in almost every human malignancy. The E2F transcription factors function in cell cycle control and are intimately regulated by RB. Studies of model organisms have revealed conserved functions for E2Fs during development, suggesting that the cancer-related proliferative roles of E2F family members represent a recent evolutionary adaptation. However, given that some human tumours have concurrent RB1 inactivation and E2F amplification and overexpression, we propose that there are alternative tumour-promoting activities for the E2F family, which are independent of cell cycle regulation.

Chen, Hui-Zi; Tsai, Shih-Yin; Leone, Gustavo

2012-01-01

244

TopBP1 Regulates Human Papillomavirus Type 16 E2 Interaction with Chromatin?  

PubMed Central

Human papillomavirus type 16 (HPV16) E2 regulates transcription from and replication of the viral genome, in association with viral and cellular factors. HPV16 E2 interacts functionally with TopBP1, a cellular protein essential for the initiation of cellular, and potentially viral, DNA replication. This report demonstrates that the absence of TopBP1 results in the redistribution of HPV16 E2 into an alternative cellular protein complex, resulting in enhanced affinity for chromatin. This redistribution does not significantly alter the ability of HPV16 E2 to either activate or repress transcription. We also show colocalization of both proteins on chromatin at late stages of mitosis, suggesting that TopBP1 could be the mitotic chromatin receptor for HPV16 E2. The possible significance of the results for the regulation of the viral life cycle is discussed.

Donaldson, Mary M.; Boner, Winifred; Morgan, Iain M.

2007-01-01

245

TAL1/SCL relieves the E2-2-mediated repression of VEGFR2 promoter activity.  

PubMed

The basic helix-loop-helix (bHLH) protein TAL1/SCL is essential for embryonic-vascular development. TAL1/SCL regulates the activation of endothelial cells by binding directly or indirectly to DNA sequences in critical target genes. We recently demonstrated that E-box protein E2-2 blocks endothelial cell activation via perturbation of VEGFR2 promoter activity. Herein, we report that TAL1/SCL interacts with E2-2 and inhibits E2-2-mediated effects on reporter activity. Mutational analysis revealed that the HLH domain of TAL1/SCL, but not its basic region, is required for interaction with E2-2. Importantly, TAL1/SCL relieves the E2-2-mediated repression of VEGFR2 reporter activity in endothelial cells. Our data elaborate on the bHLH protein interactions that regulate endothelial cell activation. PMID:19029143

Tanaka, Aya; Itoh, Fumiko; Itoh, Susumu; Kato, Mitsuyasu

2008-11-23

246

Dual mechanisms of repression of E2F1 activity by the retinoblastoma gene product.  

PubMed

The retinoblastoma gene product, pRb, negatively regulates cell proliferation by modulating the activity of the transcription factor E2F1 that controls expression of S-phase genes. To dissect transcriptional regulation of E2F1 by pRb, we developed a means to control the subcellular localization of pRb by exchanging its constitutive nuclear localization signal (NLS) with an inducible nuclear targeting domain from the glucocorticoid receptor (GR). In co-transfection experiments in hormone-free media, pRb delta NLS-GR sequestered E2F1 in the cytoplasm; addition of steroid hormones induced co-translocation of pRb delta NLS-GR and E2F1 to the nucleus. A pRb allele lacking a NLS, pRb delta NLS, also sequestered E2F1 in the cytoplasm. Both nuclear and cytoplasmic pRb delta NLS-GR repressed transcription from a simple, E2F1-activated, promoter equally well. pRb delta NLS-GR exerted differential effects on complex promoters containing an activator and E2F sites that acted as either positive or negative elements. We propose a dual mechanism of transcriptional repression by pRb which allows tight control of E2F1-responsive genes: a pRb-E2F1 repressor unit is assembled off DNA to pre-empt transcriptional activation by E2F1; recruitment of this repressor unit to cognate binding sites on promoters allows silencing of adjacent promoter elements. PMID:8918469

Zacksenhaus, E; Jiang, Z; Phillips, R A; Gallie, B L

1996-11-01

247

Observation of a molecular frame (e, 2e) cross section: an (e, 2e + M) triple coincidence study on H(2).  

PubMed

We report the first experimental results showing transition-specific anisotropy of molecular frame (e, 2e) cross sections. Vector correlations between the two outgoing electrons and the fragment ion have been measured for specific ionization-excitation processes of H2. The results enable us to obtain molecular frame (e, 2e) cross sections for transitions to the 2ssigma(g) and 2psigma(u) excited states of H(2)(+), thereby making stereodynamics of the electron-molecule collisions directly visible. PMID:16090319

Takahashi, M; Watanabe, N; Khajuria, Y; Udagawa, Y; Eland, J H D

2005-06-02

248

Short-term effects of environmentally relevant concentrations of EDC mixtures on Mytilus galloprovincialis digestive gland.  

PubMed

Endocrine disrupting compounds (EDCs), including both natural estrogens and estrogenic chemicals, are almost ubiquitous in the aquatic environment. In the marine bivalve Mytilus galloprovincialis different estrogenic compounds, both individually and in mixtures, were shown to affect the immune function both in vitro and in vivo. Moreover, individual estrogens, the natural estrogen 17beta-estradiol (E(2)) and the xenoestrogen bisphenol A (BPA), have been recently demonstrated to alter functional parameters and gene expression in mussel digestive gland, a tissue that plays a central role in metabolism and in nutrient distribution to the gonad during gamete maturation, with possible consequences on gametogenesis. In this work, the possible effects of a synthetic mixture of EDCs on the digestive gland were evaluated. The mixture contained seven estrogenic chemicals (17beta-estradiol, 17alpha-ethynyl estradiol, mestranol (MES), nonylphenol, nonylphenol monoethoxylate carboxylate (NP1EC), BPA, benzophenone (BP)), in proportions similar to those previously found in water samples of a coastal lagoon. Mussels were injected with different concentrations of the mixture (approximate nominal concentrations of total EDCs: 0.0177, 0.177, 1.77 and 177 ng/g dw) and tissues sampled 24 h post-injection. The mixture induced significant changes in lysosomal biomarkers (lysosomal membrane stability (LMS), neutral lipid (NL) and lipofuscin (LF) accumulation) as well as in the activities of catalase, glutathione transferase (GST), and of the glycolytic enzymes phosphofructokinase (PFK) and pyruvate kinase (PK). Moreover, downregulation of the gene transcription for the Mytilus estrogen receptor MeER1 isoform and for catalase, as evaluated by quantitative RT-PCR, were observed. Significant changes in lysosomal biomarkers, enzyme activities and gene transcription were also recorded at 72 h post-injection. The results demonstrate that short-term exposure to environmentally relevant concentrations of EDC mixtures can interfere with the lysosomal function, redox-related enzyme activities and gene transcription of mussel digestive gland. PMID:18374427

Canesi, Laura; Borghi, Cristina; Ciacci, Caterina; Fabbri, Rita; Lorusso, Lucia Cecilia; Vergani, Laura; Marcomini, Antonio; Poiana, Giulio

2008-03-10

249

Functional domains of Agrobacterium tumefaciens single-stranded DNA-binding protein VirE2.  

PubMed Central

The transferred DNA (T-DNA) portion of the Agrobacterium tumefaciens tumor-inducing (Ti) plasmid enters infected plant cells and integrates into plant nuclear DNA. Direct repeats define the T-DNA ends; transfer begins when the VirD2 endonuclease produces a site-specific nick in the right-hand border repeat and attaches to the 5' end of the nicked strand. Subsequent events liberate the lower strand of the T-DNA from the Ti plasmid, producing single-stranded DNA molecules (T strands) that are covalently linked to VirD2 at their 5' ends. A. tumefaciens appears to transfer T-DNA into plant cells as a T-strand-VirD2 complex. The bacterium also transports VirE2, a cooperative single-stranded DNA-binding protein, into plant cells during infection. Both VirD2 and VirE2 contain nuclear localization signals that may direct these proteins, and bound T strands, into plant nuclei. Here we report the locations of functional regions of VirE2 identified by eight insertions of XhoI linker oligonucleotides, and one deletion mutation, throughout virE2. We examined the effects of these mutations on virulence, single-stranded DNA (ssDNA) binding, and accumulation of VirE2 in A. tumefaciens. Two of the mutations in the C-terminal half of VirE2 eliminated ssDNA binding, whereas two insertions in the N-terminal half altered cooperativity. Four of the mutations, distributed throughout virE2, decreased the stability of VirE2 in A. tumefaciens. In addition, we isolated a mutation in the central region of VirE2 that decreased tumorigenicity but did not affect ssDNA binding or VirE2 accumulation. This mutation may affect export of VirE2 into plant cells or nuclear localization of VirE2, or it may affect an uncharacterized activity of VirE2.

Dombek, P; Ream, W

1997-01-01

250

Reconstitution of papillomavirus E2-mediated plasmid maintenance in Saccharomyces cerevisiae by the Brd4 bromodomain protein  

Microsoft Academic Search

The papillomavirus E2 protein functions in viral transcriptional regulation, DNA replication, and episomal genome maintenance. Viral genomes are maintained in dividing cells by attachment to mitotic chromosomes by means of the E2 protein. To investigate the chromosomal tethering function of E2, plasmid stability assays were developed in Saccharomyces cerevisiae to determine whether the E2 protein could maintain plasmids containing the

Angela R. Brannon; Julia A. Maresca; Jef D. Boeke; Munira A. Basrai; Alison A. McBride

2005-01-01

251

Hox and a newly identified E2F co-repress cell death in Caenorhabditis elegans.  

PubMed

The development of an organism depends on individual cells receiving and executing their specific fates, although how this process is regulated remains largely unknown. Here, we identify a mechanism by which a specific cell fate, apoptosis, is determined through the cooperative efforts of Hox and E2F proteins. E2F transcription factors are critical, conserved regulators of the cell cycle and apoptosis. However, little is known about the two most recently discovered mammalian E2Fs-E2F7 and E2F8. In the nematode Caenorhabditis elegans, we identify a novel E2F7/8 homolog, EFL-3, and show that EFL-3 functions cooperatively with LIN-39, providing the first example in which these two major developmental pathways-E2F and Hox-are able to directly regulate the same target gene. Our studies demonstrate that LIN-39 and EFL-3 function in a cell type-specific context to regulate transcription of the egl-1 BH3-only cell death gene and to determine cell fate during development. PMID:21596899

Winn, Jennifer; Carter, Monique; Avery, Leon; Cameron, Scott

2011-05-19

252

OTUB1 co-opts Lys48-linked ubiquitin recognition to suppress E2 enzyme function  

PubMed Central

SUMMARY Ubiquitylation entails the concerted action of E1, E2 and E3 enzymes. We recently reported that OTUB1, a deubiquitylase, inhibits the DNA damage response independently of its isopeptidase activity. OTUB1 does so by blocking ubiquitin transfer by UBC13, the cognate E2 enzyme for RNF168. OTUB1 also inhibits E2s of the UBE2D and UBE2E families. Here we elucidate the structural mechanism by which OTUB1 binds E2s to inhibit ubiquitin transfer. OTUB1 recognizes ubiquitin-charged E2s through contacts with both donor ubiquitin and the E2 enzyme. Surprisingly, free ubiquitin associates with the canonical distal ubiquitin-binding site on OTUB1 to promote formation of the inhibited E2 complex. Lys48 of donor ubiquitin lies near the OTUB1 catalytic site and the C-terminus of free ubiquitin, a configuration that mimics the products of Lys48-linked ubiquitin chain cleavage. OTUB1 therefore co-opts Lys48-linked ubiquitin chain recognition to suppress ubiquitin conjugation and the DNA damage response.

Juang, Yu-Chi; Landry, Marie-Claude; Sanches, Mario; Vittal, Vinayak; Leung, Charles; Ceccarelli, Derek F.; Mateo, Abigail-Rachele F.; Pruneda, Jonathan N.; Mao, Dan; Szilard, Rachel K.; Orlicky, Stephen; Munro, Meagan; Brzovic, Peter S.; Klevit, Rachel E.; Sicheri, Frank; Durocher, Daniel

2012-01-01

253

OTUB1 co-opts Lys48-linked ubiquitin recognition to suppress E2 enzyme function.  

PubMed

Ubiquitylation entails the concerted action of E1, E2, and E3 enzymes. We recently reported that OTUB1, a deubiquitylase, inhibits the DNA damage response independently of its isopeptidase activity. OTUB1 does so by blocking ubiquitin transfer by UBC13, the cognate E2 enzyme for RNF168. OTUB1 also inhibits E2s of the UBE2D and UBE2E families. Here we elucidate the structural mechanism by which OTUB1 binds E2s to inhibit ubiquitin transfer. OTUB1 recognizes ubiquitin-charged E2s through contacts with both donor ubiquitin and the E2 enzyme. Surprisingly, free ubiquitin associates with the canonical distal ubiquitin-binding site on OTUB1 to promote formation of the inhibited E2 complex. Lys48 of donor ubiquitin lies near the OTUB1 catalytic site and the C terminus of free ubiquitin, a configuration that mimics the products of Lys48-linked ubiquitin chain cleavage. OTUB1 therefore co-opts Lys48-linked ubiquitin chain recognition to suppress ubiquitin conjugation and the DNA damage response. PMID:22325355

Juang, Yu-Chi; Landry, Marie-Claude; Sanches, Mario; Vittal, Vinayak; Leung, Charles C Y; Ceccarelli, Derek F; Mateo, Abigail-Rachele F; Pruneda, Jonathan N; Mao, Daniel Y L; Szilard, Rachel K; Orlicky, Stephen; Munro, Meagan; Brzovic, Peter S; Klevit, Rachel E; Sicheri, Frank; Durocher, Daniel

2012-02-10

254

E2 ubiquitin-conjugating enzymes regulate the deubiquitinating activity of OTUB1.  

PubMed

OTUB1 is a Lys48-specific deubiquitinating enzyme that forms a complex in vivo with E2 ubiquitin (Ub)-conjugating enzymes including UBC13 and UBCH5. OTUB1 binds E2~Ub thioester intermediates and prevents ubiquitin transfer, thereby noncatalytically inhibiting accumulation of polyubiquitin. We report here that a second role of OTUB1-E2 interactions is to stimulate OTUB1 cleavage of Lys48 polyubiquitin. This stimulation is regulated by the ratio of charged to uncharged E2 and by the concentration of Lys48-linked polyubiquitin and free ubiquitin. Structural and biochemical studies of human and worm OTUB1 and UBCH5B show that the E2 enzyme stimulates binding of the Lys48 polyubiquitin substrate by stabilizing folding of the OTUB1 N-terminal ubiquitin-binding helix. Our results suggest that OTUB1-E2 complexes in the cell are poised to regulate polyubiquitin chain elongation or degradation in response to changing levels of E2 charging and available free ubiquitin. PMID:23955022

Wiener, Reuven; Dibello, Anthony T; Lombardi, Patrick M; Guzzo, Catherine M; Zhang, Xiangbin; Matunis, Michael J; Wolberger, Cynthia

2013-08-18

255

Functional interaction of a novel cellular protein with the papillomavirus E2 transactivation domain.  

PubMed Central

The transactivation domain (AD) of bovine papillomavirus type 1 E2 stimulates gene expression and DNA replication. To identify cellular proteins that interact with this 215-amino-acid domain, we used a transactivation-defective mutant as bait in the yeast two-hybrid screen. In vitro and in vivo results demonstrate that the cDNA of one plasmid isolated in this screen encodes a 37-kDa nuclear protein that specifically binds to an 82-amino-acid segment within the E2 AD. Mutants with point mutations within this E2 domain were isolated based on their inability to interact with AMF-1 and were found to be unable to stimulate transcription. These mutants also exhibited defects in viral DNA replication yet retained binding to the viral E1 replication initiator protein. Overexpression of AMF-1 stimulated transactivation by both wild-type E2 and a LexA fusion to the E2 AD, indicating that AMF-1 is a positive effector of the AD of E2. We conclude that interaction with AMF-1 is necessary for the transcriptional activation function of the E2 AD in mammalian cells.

Breiding, D E; Sverdrup, F; Grossel, M J; Moscufo, N; Boonchai, W; Androphy, E J

1997-01-01

256

Insights into Nuclear Triaxiality from Interference Effects in E2 Matrix Elements  

NASA Astrophysics Data System (ADS)

Recently, we have introduced [1] a triaxial rotor model with independent inertia and E2 tensors. The E2 matrix elements [2] of the osmium isotopes (186, 188, 190, and 192) are studied in the framework of this model (59 of 84 E2 matrix elements deviate by 30% or less). It is shown that interference effects in the inertia tensor (K-mixing) and the E2 tensor can lead to significant reductions in the diagonal E2 matrix elements. In some instances, the diagonal E2 matrix elements may decrease with increasing spin. Additionally, a sum rule for diagonal E2 matrix elements is shown and used to explore missing strength from K-admixtures. [1] J.L. Wood, A-M. Oros-Peusquens, R. Zaballa, J.M. Allmond, and W.D. Kulp, Phys. Rev. C 70, 024308 (2004). [2] C.Y. Wu, D. Cline, T. Czosnyka, A. Backlin, C. Baktash, R.M. Diamond, G.D. Dracoulis, L. Hasselgren, H. Kluge, et al., Nucl. Phys. A607, 178 (1996).

Allmond, J. M.; Wood, J. L.; Kulp, W. D.

2007-10-01

257

Repression of Transcriptional Activity of C/EBP? by E2F-Dimerization Partner Complexes?†  

PubMed Central

The transcription factor CCAAT/enhancer-binding protein ? (C/EBP?) coordinates proliferation arrest and the differentiation of myeloid progenitors, adipocytes, hepatocytes, keratinocytes, and cells of the lung and placenta. C/EBP? transactivates lineage-specific differentiation genes and inhibits proliferation by repressing E2F-regulated genes. The myeloproliferative C/EBP? BRM2 mutant serves as a paradigm for recurrent human C-terminal bZIP C/EBP? mutations that are involved in acute myeloid leukemogenesis. BRM2 fails to repress E2F and to induce adipogenesis and granulopoiesis. The data presented here show that, independently of pocket proteins, C/EBP? interacts with the dimerization partner (DP) of E2F and that C/EBP?-E2F/DP interaction prevents both binding of C/EBP? to its cognate sites on DNA and transactivation of C/EBP target genes. The BRM2 mutant, in addition, exhibits enhanced interaction with E2F-DP and reduced affinity toward DNA and yet retains transactivation potential and differentiation competence that becomes exposed when E2F/DP levels are low. Our data suggest a tripartite balance between C/EBP?, E2F/DP, and pocket proteins in the control of proliferation, differentiation, and tumorigenesis.

Zaragoza, Katrin; Begay, Valerie; Schuetz, Anja; Heinemann, Udo; Leutz, Achim

2010-01-01

258

A BIPOLAR OUTFLOW FROM THE MASSIVE PROTOSTELLAR CORE W51e2-E  

SciTech Connect

We present high-resolution images of the bipolar outflow from W51e2, which are produced from the Submillimeter Array archival data observed for CO(3-2) and HCN(4-3) lines with angular resolutions of 0.''8 x 0.''6 and 0.''3 x 0.''2, respectively. The images show that the powerful outflow originates from the protostellar core W51e2-E rather than from the ultracompact H II region W51e2-W. The kinematic timescale of the outflow from W51e2-E is about 1000 yr, younger than the age ({approx}5000 yr) of the ultracompact H II region W51e2-W. A large mass-loss rate of {approx}1 x 10{sup -3} M{sub sun} yr{sup -1} and a high mechanical power of 120 L{sub sun} are inferred, suggesting that an O star or a cluster of B stars are forming in W51e2-E. The observed outflow activity along with the inferred large accretion rate indicates that at present W51e2-E is in a rapid phase of star formation.

Shi Hui; Han, J. L. [National Astronomical Observatories, Chinese Academy of Sciences, 20A DaTun Road, Beijing 100012 (China); Zhao Junhui, E-mail: shihui@nao.cas.c, E-mail: hil@nao.cas.c, E-mail: jzhao@cfa.harvard.ed [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2010-08-01

259

Inhibition of sodium transport by prostaglandin E2 across the isolated, perfused rabbit collecting tubule.  

PubMed Central

This study was designed to examine whether prostaglandin E2 can directly affect sodium transport across isolated perfused rabbit renal collecting tubules. Changes in transepithelial potential and isotopic sodium fluxes in response to peritubular prostaglandin E2 were measured. In addition, changes in transepithelial potential of the outer medullary collecting tubule in response to prostaglandin E2 were also measured. With few exceptions, all rabbits received 5 mg/day desoxycorticosterone acetate for 4-11 days before experimentation. The results of the experiments show that: (a) prostaglandin E2 inhibits the negative transepithelial potential in the cortical collecting tubule as well as the outer medullary collecting tubule; (b) prostaglandin E2 inhibits net sodium transport out of the lumen by inhibiting efflux while backflux is unaffected; (c) prostaglandin E2 produces this inhibition within 15 min, and the effects are dose dependent and reversible. These results suggest that prostaglandin E2 may modulate sodium transport in vivo and may contribute to the final regulation of sodium excretion.

Stokes, J B; Kokko, J P

1977-01-01

260

E2F3 plays an essential role in cardiac development and function  

PubMed Central

The E2F transcription factors are key downstream targets of the retinoblastoma protein tumor suppressor. They are known to regulate the expression of genes that control fundamental biological processes including cellular proliferation, apoptosis and differentiation. However, considerable questions remain about the precise roles of the individual E2F family members. This study shows that E2F3 is essential for normal cardiac development. E2F3-loss impairs the proliferative capacity of the embryonic myocardium and most E2f3?/? mice die in utero or perinatally with hypoplastic ventricular walls and/or severe atrial and ventricular septal defects. A small fraction of the E2f3?/? neonates have hearts that appear grossly normal and they initially survive. However, these animals develop ultrastructural defects in the cardiac muscle and ultimately die as a result of congestive heart failure. These data demonstrate a clear link between E2F3’s role in the proliferative capacity of the myocardium and cardiac function during both development and adulthood.

King, Jennifer C.; Moskowitz, Ivan P. G.; Burgon, Patrick G.; Ahmad, Ferhaan; Stone, James R.; Seidman, Jonathan G.; Lees, Jacqueline A.

2009-01-01

261

Expression of bovine viral diarrhoea virus glycoprotein E2 by bovine herpesvirus-1 from a synthetic ORF and incorporation of E2 into recombinant virions  

Microsoft Academic Search

Expression cassettes containing the codons for the pestivirus E rns signal peptide (Sig) followed by a chemically synthesized ORF that encoded the bovine viral diarrhoea virus (BVDV) strain C86 glycoprotein E2, a class I membrane glycoprotein, were constructed with and without a chimeric intron sequence immediately upstream of the translation start codon, and incorporated into the genome of bovine herpesvirus-1

Jutta Schmitt; Paul Becher; M. Keil

1999-01-01

262

Ectopic Expression of E2F1 Stimulates ?-Cell Proliferation and Function  

PubMed Central

OBJECTIVE Generating functional ?-cells by inducing their proliferation may provide new perspectives for cell therapy in diabetes. Transcription factor E2F1 controls G1- to S-phase transition during the cycling of many cell types and is required for pancreatic ?-cell growth and function. However, the consequences of overexpression of E2F1 in ?-cells are unknown. RESEARCH DESIGN AND METHODS The effects of E2F1 overexpression on ?-cell proliferation and function were analyzed in isolated rat ?-cells and in transgenic mice. RESULTS Adenovirus AdE2F1-mediated overexpression of E2F1 increased the proliferation of isolated primary rat ?-cells 20-fold but also enhanced ?-cell death. Coinfection with adenovirus AdAkt expressing a constitutively active form of Akt (protein kinase B) suppressed ?-cell death to control levels. At 48 h after infection, the total ?-cell number and insulin content were, respectively, 46 and 79% higher in AdE2F1+AdAkt-infected cultures compared with untreated. Conditional overexpression of E2F1 in mice resulted in a twofold increase of ?-cell proliferation and a 70% increase of pancreatic insulin content, but did not increase ?-cell mass. Glucose-challenged insulin release was increased, and the mice showed protection against toxin-induced diabetes. CONCLUSIONS Overexpression of E2F1, either in vitro or in vivo, can stimulate ?-cell proliferation activity. In vivo E2F1 expression significantly increases the insulin content and function of adult ?-cells, making it a strategic target for therapeutic manipulation of ?-cell function.

Grouwels, Gael; Cai, Ying; Hoebeke, Inge; Leuckx, Gunter; Heremans, Yves; Ziebold, Ulrike; Stange, Geert; Chintinne, Marie; Ling, Zhidong; Pipeleers, Daniel; Heimberg, Harry; Van de Casteele, Mark

2010-01-01

263

E2F1 loss induces spontaneous tumour development in Rb-deficient epidermis.  

PubMed

The specific ablation of Rb1 gene in epidermis (Rb(F/F);K14cre) promotes proliferation and altered differentiation but does not produce spontaneous tumour development. These phenotypic changes are associated with increased expression of E2F members and E2F-dependent transcriptional activity. Here, we have focused on the possible dependence on E2F1 gene function. We have generated mice that lack Rb1 in epidermis in an inducible manner (Rb(F/F);K14creER(TM)). These mice are indistinguishable from those lacking pRb in this tissue in a constitutive manner (Rb(F/F);K14cre). In an E2F1-null background (Rb(F/F);K14creER(TM); and E2F1(-/-) mice), the phenotype due to acute Rb1 loss is not ameliorated by E2F1 loss, but rather exacerbated, indicating that pRb functions in epidermis do not rely solely on E2F1. On the other hand, Rb(F/F);K14creER(TM);E2F1(-/-) mice develop spontaneous epidermal tumours of hair follicle origin with high incidence. These tumours, which retain a functional p19(arf)/p53 axis, also show aberrant activation of ?-catenin/Wnt pathway. Gene expression studies revealed that these tumours display relevant similarities with specific human tumours. These data demonstrate that the Rb/E2F1 axis exerts essential functions not only in maintaining epidermal homoeostasis, but also in suppressing tumour development in epidermis, and that the disruption of this pathway may induce tumour progression through specific alteration of developmental programs. PMID:22890321

Costa, C; Santos, M; Martínez-Fernández, M; Dueñas, M; Lorz, C; García-Escudero, R; Paramio, J M

2012-08-13

264

Effect of Bovine Papillomavirus E2 Protein-Specific Monoclonal Antibodies on Papillomavirus DNA Replication  

PubMed Central

The bovine papillomavirus type 1 (BPV-1) E2 protein is the master regulator of papillomavirus replication and transcription. We have raised a panel of monoclonal antibodies (MAbs) against the BPV-1 E2 protein and used them to probe the structure and function of the protein. Five MAbs reacted with linear epitopes, and four MAbs recognized conformation-dependent epitopes which mapped within the C-terminal DNA-binding and dimerization domain. MAb 1E2 was able to recognize the replication- and transactivation-defective but not the competent conformation of the transactivation domain of the E2 protein. MAb 5H4 prevented efficiently the formation of E2-DNA as well as E2-dependent E1-E2-origin complexes and also dissociated preformed complexes in a concentration-dependent manner. Cotransfection of several MAbs with the BPV-1 minimal origin plasmid pUCAlu into CHO4.15 cells resulted in a dose-dependent inhibition of replication. Inhibition of replication by MAb 5H4 and the Fab? fragment of 5H4 correlated with their ability to dissociate the E2 protein from the DNA. MAb 3F12 and MAbs 1H10 and 1E4, directed against the hinge region, were also capable of inhibiting BPV-1 origin replication in CHO4.15 cells. However, the Fab? fragments of 1H10 and 3F12 had no effect in the transient replication assay. These data suggest that MAbs directed against the hinge region sterically hinder the inter- or intramolecular interactions required for the replication activity of the E2 protein.

Kurg, Reet; Parik, Juri; Juronen, Erkki; Sedman, Tiina; Abroi, Aare; Liiv, Ingrid; Langel, Ulo; Ustav, Mart

1999-01-01

265

Structural Insights into the Conformation and Oligomerization of E2~Ubiquitin Conjugates  

PubMed Central

Post-translational modification of proteins by ubiquitin (Ub) regulates a host of cellular processes including protein quality control, DNA repair, endocytosis and cellular signaling. In the ubiquitination cascade, a thioester-linked conjugate between the Ub C-terminus and the active site cysteine of a ubiquitin-conjugating enzyme (E2) is formed. The E2~Ub conjugate interacts with a ubiquitin ligase (E3) to transfer Ub to a lysine residue on a target protein. The flexibly-linked E2~Ub conjugates have been shown to form a range of structures in solution. In addition, select E2~Ub conjugates oligomerize through a noncovalent “backside” interaction between Ub and E2 components of different conjugates. Additional studies are needed to bridge the gap between the dynamic monomeric conjugates, E2~Ub oligomers and the mechanisms of ubiquitination. We present a new 2.35 Å crystal structure of an oligomeric UbcH5c~Ub conjugate. The conjugate forms a staggered linear oligomer that differs substantially from the “infinite spiral” helical arrangement of the sole previously reported structure of an oligomeric conjugate. Our structure also differs in intra-conjugate conformation from other structurally characterized conjugates. Despite these differences, we find that the backside interaction mode is conserved in different conjugate oligomers and is independent of intra-conjugate relative E2/Ub orientations. We delineate a common intra-conjugate E2-binding surface on Ub. In addition, we demonstrate that an E3 ligase CHIP (carboxyl terminus of Hsp70 interacting protein) interacts directly with UbcH5c~Ub oligomers, not only with conjugate monomers. These results provide insights into the conformational diversity of E2~Ub conjugates and conjugate oligomers, and into their compatibility and interactions with E3 ligases, which have important consequences for the ubiquitination process.

Page, Richard C.; Pruneda, Jonathan N.; Amick, Joseph; Klevit, Rachel E.; Misra, Saurav

2012-01-01

266

Repression of Androgen Receptor Transcription through the E2F1/DNMT1 Axis  

PubMed Central

Although androgen receptor (AR) function has been extensively studied, regulation of the AR gene itself has been much less characterized. In this study, we observed a dramatic reduction in the expression of androgen receptor mRNA and protein in hyperproliferative prostate epithelium of keratin 5 promoter driven E2F1 transgenic mice. To confirm an inhibitory function for E2F1 on AR transcription, we showed that E2F1 inhibited the transcription of endogenous AR mRNA, subsequent AR protein, and AR promoter activity in both human and mouse epithelial cells. E2F1 also inhibited androgen-stimulated activation of two AR target gene promoters. To elucidate the molecular mechanism of E2F-mediated inhibition of AR, we evaluated the effects of two functional E2F1 mutants on AR promoter activity and found that the transactivation domain appears to mediate E2F1 repression of the AR promoter. Because DNMT1 is a functional intermediate of E2F1 we examined DNMT1 function in AR repression. Repression of endogenous AR in normal human prostate epithelial cells was relieved by DNMT1 shRNA knock down. DNMT1 was shown to be physically associated within the AR minimal promoter located 22 bps from the transcription start site; however, methylation remained unchanged at the promoter regardless of DNMT1 expression. Taken together, our results suggest that DNMT1 operates either as a functional intermediary or in cooperation with E2F1 inhibiting AR gene expression in a methylation independent manner.

Valdez, Conrad David; Davis, Joanne N.; Odeh, Hana M.; Layfield, Tristan L.; Cousineau, Craig S.; Berton, Thomas R.; Johnson, David G.; Wojno, Kirk J.; Day, Mark L.

2011-01-01

267

Repression of androgen receptor transcription through the E2F1/DNMT1 axis.  

PubMed

Although androgen receptor (AR) function has been extensively studied, regulation of the AR gene itself has been much less characterized. In this study, we observed a dramatic reduction in the expression of androgen receptor mRNA and protein in hyperproliferative prostate epithelium of keratin 5 promoter driven E2F1 transgenic mice. To confirm an inhibitory function for E2F1 on AR transcription, we showed that E2F1 inhibited the transcription of endogenous AR mRNA, subsequent AR protein, and AR promoter activity in both human and mouse epithelial cells. E2F1 also inhibited androgen-stimulated activation of two AR target gene promoters. To elucidate the molecular mechanism of E2F-mediated inhibition of AR, we evaluated the effects of two functional E2F1 mutants on AR promoter activity and found that the transactivation domain appears to mediate E2F1 repression of the AR promoter. Because DNMT1 is a functional intermediate of E2F1 we examined DNMT1 function in AR repression. Repression of endogenous AR in normal human prostate epithelial cells was relieved by DNMT1 shRNA knock down. DNMT1 was shown to be physically associated within the AR minimal promoter located 22 bps from the transcription start site; however, methylation remained unchanged at the promoter regardless of DNMT1 expression. Taken together, our results suggest that DNMT1 operates either as a functional intermediary or in cooperation with E2F1 inhibiting AR gene expression in a methylation independent manner. PMID:21966451

Valdez, Conrad David; Davis, Joanne N; Odeh, Hana M; Layfield, Tristan L; Cousineau, Craig S; Berton, Thomas R; Johnson, David G; Wojno, Kirk J; Day, Mark L

2011-09-26

268

Protein ubiquitination involving an E1-E2-E3 enzyme ubiquitin thioester cascade  

Microsoft Academic Search

UBIQUITINATION of proteins involves the concerted action of the El ubiquitin-activating enzyme, E2 ubiquitin-conjugating enzymes and E3 ubiquitin-protein 1igases1-3. It has been proposed that E3s function as 'docking proteins', specifically binding substrate proteins and specific E2s, and that ubiquitin is then transferred directly from E2s to substrates1-5. We show here that formation of a ubiquitin thioester on E6-AP, an E3

Martin Scheffner; Ulrike Nuber; Jon M. Huibregtse

1995-01-01

269

Structure of the CIAP2 Ring Domain Reveal Conformational Changes Associated With E2 Recruitment  

SciTech Connect

Inhibitor of apoptosis (IAP) proteins are key negative regulators of cell death that are highly expressed in many cancers. Cell death caused by antagonists that bind to IAP proteins is associated with their ubiquitylation and degradation. The RING domain at the C terminus of IAP proteins is pivotal. Here we report the crystal structures of the cIAP2 RING domain homodimer alone, and bound to the ubiquitin-conjugating (E2) enzyme UbcH5b. These structures show that small changes in the RING domain accompany E2 binding. By mutating residues at the E2-binding surface, we show that autoubiquitylation is required for regulation of IAP abundance. Dimer formation is also critical, and mutation of a single C-terminal residue abrogated dimer formation and E3 ligase activity was diminished. We further demonstrate that disruption of E2 binding, or dimerization, stabilizes IAP proteins against IAP antagonists in vivo.

Mace, P.D.; Linke, K.; Feltham, R.; Schumacher, F.-R.; Smith, C.A.; Vaux, D.L.; Silke, J.; Day, C.L.

2009-05-19

270

Laboratory and radiation performance testing results for the e2v model 212 CCD  

Microsoft Academic Search

The e2v CCD212 was designed and developed explicitly to support very high accuracy astrometric observations in moderate radiation environments in space. One of the major new innovations in the detector is the use of \\

Bryan N. Dorland; Roger Foltz; Augustyn Waczynski

2007-01-01

271

A role for E2F6 in distinguishing G1/S- and G2/M-specific transcription  

PubMed Central

E2F transcription factors play a critical role in the control of cell cycle progression, regulating the expression of genes involved in DNA replication, DNA repair, mitosis, and cell fate. This involves both positive-acting and negative-acting E2F proteins, the latter group including the E2F6 protein, which has been shown to function as an Rb-independent repressor of E2F-target gene transcription. In an effort to better delineate the context of E2F6 function, including the mechanisms of E2F6 functional specificity, we used chromatin immunoprecipitation assays to assess when and with what genes E2F6 associates during a cell cycle. We find that E2F6 associates specifically with the E2F target genes that are activated at G1/S; this interaction occurs during S phase of the cell cycle. In sharp contrast, E2F6 does not bind to E2F-regulated genes activated at G2/M. In the absence of E2F6, E2F4 can bind to the G1/S-regulated promoters and compensate for loss of E2F6 function. Indeed, inhibition of both E2F4 and E2F6 activity results in specific derepression of these genes during S phase. We conclude that E2F6 functions as a repressor of E2F-dependent transcription during S phase and given the specificity for the G1/S-regulated genes, we propose that E2F6 functions to distinguish G1/S and G2/M transcription during the cell cycle.

Giangrande, Paloma H.; Zhu, Wencheng; Schlisio, Susanne; Sun, Xin; Mori, Seiichi; Gaubatz, Stefan; Nevins, Joseph R.

2004-01-01

272

UHMWPE carrying estradiol to treat the particle-induced osteolysis-Processing and characterizing.  

PubMed

The objective of this study was to explore the possibility of UHMWPE implant used as the drug carrier to treat particle-induced osteolysis. 17beta-estradiol (E2), which had the potential application on osteolysis treatment and the high melting point, was added into UHMWPE powder to produce UHMWPE-E2 composites through hot press processing. The hydrophobicity, crystallinity, mechanical properties, and wear performance of the UHMWPE-E2 were characterized compared with the control UHMWPE. The thermal analysis and Fourier Transform Infrared Spectroscopy results demonstrated that the hot press processing would not alter the functional groups of E2 in this study. There were no significant differences in the hydrophobicity and crystallinity between the UHMWPE-E2 and UHMWPE. The UHMWPE-E2 showed satisfying mechanical properties, including ultimate tensile strength (47.2 +/- 3.6 MPa), yield strength (25.0 +/- 0.6 MPa) and elongation at break (320 +/- 25.5 %), which were similar with the control UHMWPE. The friction coefficients and worn scars were similar between the UHMWPE-E2 and the control UHMWPE. The wear mechanism of the UHMWPE-E2 and UHMWPE both were abrasive wear under dry friction. The UHMWPE-E2 possesses the approving mechanical properties and wear performance compared with the control UHMWPE, which might be used as the potential implanted drug carrier to prevent the particle-induced osteolysis in joint replacements. PMID:18563828

Liu, Aiqin; Qu, Shuxin; Chao, Mengmeng; Zhu, Minhao; Weng, Jie; Zhou, Zhongrong

2009-08-01

273

Functional interplay between p53 and E2F through co-activator p300  

Microsoft Academic Search

Both E2F and p53 are sequence specific transcription factors that regulate early cell cycle progression. The pathway of control mediated through E2F governs the transition from G1 into S phase whereas p53 in response to genotoxic stress can facilitate cell cycle arrest or apoptosis. The mechanisms which influence the outcome of p53 induction are not clear, although transcription of the

Chang-Woo Lee; Troels S Sørensen; Noriko Shikama; Nicholas B La Thangue; NB La Thangue

1998-01-01

274

The Human Papillomavirus Type 8 E2 Protein Induces Skin Tumors in Transgenic Mice  

Microsoft Academic Search

Transgenic mice expressing early genes of the cutaneous human papillomavirus 8 (HPV8) spontaneously develop skin papillomas, epidermal dysplasia, and squamous cell carcinoma (6%). As the HPV8 protein E2 revealed transforming capacity in vitro, we generated three epidermal specific HPV8-E2-transgenic FVB\\/N mouse lines to dissect its role in tumor development. The rate of tumor formation in the three lines correlated with

Regina Pfefferle; Gian Paolo Marcuzzi; Baki Akgül; Hans Udo Kasper; Falko Schulze; Ingo Haase; Claudia Wickenhauser; Herbert Pfister

2008-01-01

275

Interaction of E2 Glycoprotein with Heparan Sulfate Is Crucial for Cellular Infection of Sindbis Virus  

Microsoft Academic Search

Cell culture-adapted strains of Sindbis virus (SINV) initially attach to cells by the ability to interact with heparan sulfate (HS) through selective mutation for positively charged amino acid (aa) scattered in E2 glycoprotein (W. B. Klimstra, K. D. Ryman, and R. E. Johnston, J. Virol. 72: 7357–7366, 1998). Here we have further confirmed that interaction of E2 protein with HS

Wuyang Zhu; Lihua Wang; Yiliang Yang; Juan Jia; Shihong Fu; Yun Feng; Ying He; Jin-Ping Li; Guodong Liang; Bradley S. Schneider

2010-01-01

276

Conserved functions of the pRB and E2F families  

Microsoft Academic Search

Proteins that are related to the retinoblastoma tumour suppressor pRB and the E2F transcription factor are conserved in many species of plants and animals. The mammalian orthologues of pRB and E2F are best known for their roles in cell proliferation, but it has become clear that they affect many biological processes. Here we describe the functions of pRB-related proteins and

Sander van den Heuvel; Nicholas J. Dyson

2008-01-01

277

A Genetic Screen for Modifiers of E2F in Drosophila melanogaster  

Microsoft Academic Search

The activity of the E2F transcription factor is regulated in part by pRB, the protein product of the retinoblastoma tumor suppressor gene. Studies of tumor cells show that the p16 ink4a \\/cdk4\\/cyclin D\\/pRB pathway is mutated in most forms of cancer, suggesting that the deregulation of E2F, and hence the cell cycle, is a common event in tumorigenesis. Extragenic mutations

Karen Staehling-Hampton; Phillip J. Ciampa; Adam Brook; Nicholas Dyson

1999-01-01

278

Circular dumbbell AP1 and E2F decoy oligodeoxynucleotide based antiproliferative gene therapy Review Article  

Microsoft Academic Search

Summary Excessive proliferation of cells is a characteristic finding in a wide variety of diseases including post-angioplasty restenosis, diabetic nephropathy, and malignant disease. It is well known that the transcription factors AP-1 and E2F play a critical role in cell proliferation and cell cycle regulation. Therefore, sequence-specific inhibition of AP-1 and E2F by decoy oligodeoxynucleotides (ODNs) is an attractive method

Keun-Gyu Park; Seong-Yeol Ryu; In-Kyu Lee

279

E2F and cell cycle control: a double-edged sword  

Microsoft Academic Search

The E2F family of transcription factors plays a central role in regulating cellular proliferation by controlling the expression of both the genes required for cell cycle progression, particularly DNA synthesis, and the genes involved with apoptosis. E2F is regulated in a cell cycle-dependent manner, principally through its temporal association with pocket protein family members, the prototype member being the retinoblastoma

Craig Stevens; Nicholas B La Thangue

2003-01-01

280

Identification of New Functional Regions in Hepatitis C Virus Envelope Glycoprotein E2?  

PubMed Central

Little is known about the structure of the envelope glycoproteins of hepatitis C virus (HCV). To identify new regions essential for the function of these glycoproteins, we generated HCV pseudoparticles (HCVpp) containing HCV envelope glycoproteins, E1 and E2, from different genotypes in order to detect intergenotypic incompatibilities between these two proteins. Several genotype combinations were nonfunctional for HCV entry. Of interest, a combination of E1 from genotype 2a and E2 from genotype 1a was nonfunctional in the HCVpp system. We therefore used this nonfunctional complex and the recently described structural model of E2 to identify new functional regions in E2 by exchanging protein regions between these two genotypes. The functionality of these chimeric envelope proteins in the HCVpp system and/or the cell-cultured infectious virus (HCVcc) was analyzed. We showed that the intergenotypic variable region (IgVR), hypervariable region 2 (HVR2), and another segment in domain II play a role in E1E2 assembly. We also demonstrated intradomain interactions within domain I. Importantly, we also identified a segment (amino acids [aa] 705 to 715 [segment 705-715]) in the stem region of E2, which is essential for HCVcc entry. Circular dichroism and nuclear magnetic resonance structural analyses of the synthetic peptide E2-SC containing this segment revealed the presence of a central amphipathic helix, which likely folds upon membrane binding. Due to its location in the stem region, segment 705-715 is likely involved in the reorganization of the glycoprotein complexes taking place during the fusion process. In conclusion, our study highlights new functional and structural regions in HCV envelope glycoprotein E2.

Albecka, Anna; Montserret, Roland; Krey, Thomas; Tarr, Alexander W.; Diesis, Eric; Ball, Jonathan K.; Descamps, Veronique; Duverlie, Gilles; Rey, Felix; Penin, Francois; Dubuisson, Jean

2011-01-01

281

Noncanonical E2 Variant-Independent Function of UBC13 in Promoting Checkpoint Protein Assembly  

Microsoft Academic Search

The E2 ubiquitin-conjugating enzyme UBC13 plays pivotal roles in diverse biological processes. Recent studies have elucidated that UBC13, in concert with the E3 ubiquitin ligase RNF8, propagates the DNA damage signal via a ubiquitylation-dependent signaling pathway. However, mechanistically how UBC13 mediates its role in promoting checkpoint protein assembly and its genetic requirement for E2 variants remain elusive. Here we provide

Michael S. Y. Huen; Jun Huang; Jingsong Yuan; Masahiro Yamamoto; Shizuo Akira; Carolyn Ashley; Wei Xiao; Junjie Chen

2008-01-01

282

An Agrobacterium VirE2 channel for transferred-DNA transport into plant cells  

Microsoft Academic Search

Transferred DNA (T-DNA) transfer from Agrobacterium tumefaciens into eukaryotic cells is the only known example of interkingdom DNA transfer. T-DNA is a single-stranded segment of Agrobacterium's tumor-inducing plasmid that enters the plant cell as a complex with the bacterial virulence proteins VirD2 and VirE2. The VirE2 protein is highly induced on contact of A. tumefaciens with a plant host and

Fabrice Dumas; Myriam Duckely; Pawel Pelczar; Patrick van Gelder; Barbara Hohn

2001-01-01

283

Functionality of chimeric E2 glycoproteins of BVDV and CSFV in virus replication  

Microsoft Academic Search

An intriguing difference between the E2 glycoprotein of CSFV and the other groups of pestiviruses (nonCSFV) is a lack of two cysteine residues on positions cysteine 751 and 798. Other groups of pestivirus are not restricted to one species as swine, whereas CSFV is restricted to swine and wild boar. We constructed chimeric CSFV\\/BVDV E2 genes based on a 2D

Gennip van H. G. P; G. K. W. Miedema

2008-01-01

284

Regulation of the Cyclin E Gene by Transcription Factor E2F1  

Microsoft Academic Search

A variety of results point to the transcription factor E2F as a critical determinant of the G_1\\/S-phase transition during the cell cycle in mammalian cells, serving to activate the transcription of a group of genes that encode proteins necessary for DNA replication. In addition, E2F activity appears to be directly regulated by the action of retinoblastoma protein (RB) and RB-related

Kiyoshi Ohtani; James Degregori; Joseph R. Nevin

1995-01-01

285

Cell Cycle Genes Are the Evolutionarily Conserved Targets of the E2F4 Transcription Factor  

Microsoft Academic Search

Maintaining quiescent cells in G0 phase is achieved in part through the multiprotein subunit complex known as DREAM, and in human cell lines the transcription factor E2F4 directs this complex to its cell cycle targets. We found that E2F4 binds a highly overlapping set of human genes among three diverse primary tissues and an asynchronous cell line, which suggests that

Caitlin M. Conboy; Christiana Spyrou; Natalie P. Thorne; Elizabeth J. Wade; Nuno L. Barbosa-Morais; Michael D. Wilson; Arindam Bhattacharjee; Richard A. Young; Simon Tavaré; Jacqueline A. Lees; Duncan T. Odom; Cecile Fairhead

2007-01-01

286

Characterization of E2V CCD 203_82 with low noise AACAS controller  

Microsoft Academic Search

National Astronomical Observatories of Chinese Academy of Sciences have successfully developed a universal astronomical CCD controller, which is called Astronomical Array Control & Acquisition System (AACAS). It behaves excellent performance and ultra low system noise. In this paper, results of E2V 4K×4K CCD203_82 characterization using AACAS controller are presented and also the comparison with the specifications E2V supplied is given.

Yuanyuan Shang; Qian Song; Yong Guan; Yu Song; Zhaowang Zhao

2008-01-01

287

Transcriptional Activation of the Human CD2AP Promoter by E2F1  

Microsoft Academic Search

CD2-associated protein (CD2AP) is an adaptor molecule involved in T cell receptor signaling and podocyte homeostasis. CD2AP-deficient mice develop nephritic syndrome and renal failure caused by glomerulosclerosis. Transcription factor E2F1 is a key regulator of cell proliferation and apoptosis. Here we report that E2F1 up-regulates the human CD2AP promoter and further increases the mRNA and protein levels of the human

Li Zou; Hua-Guo Xu; Wei Ren; Rui Jin; Yi Wang; Guo-Ping Zhou

2012-01-01

288

Interaction between the HPV16 E2 transcriptional activator and p53  

Microsoft Academic Search

The HPV-16 E2 protein is a major regulator of viral DNA replication and gene expression. Through interactions with the viral origin binding protein, E1, it localizes E1 to the origin of replication and stimulates the initiation of viral DNA replication. However, several recent reports have described a number of diverse activities of E2 relating to the induction of apoptosis through

Paola Massimi; David Pim; Cosetta Bertoli; Véronique Bouvard; Lawrence Banks

1999-01-01

289

Pharmacokinetics and enterohepatic circulation of (E)-2-ene valproic acid in the rat.  

PubMed

A pharmacologically active monounsaturated metabolite of valproic acid (VPA), (E)-2-ene VPA, was administered by an intravenous bolus dose of 20 mg/kg to normal and bile-exteriorized rats. The total plasma clearance of (E)-2-ene VPA in normal rats was 4.9 ml/min/kg and in bile-exteriorized rats, 7.7 ml/min/kg. (E)-2-ene was recycled in the plasma of normal rats due to enterohepatic circulation. Approximately 32% of the dose was excreted in the urine of normal rats. Of the administered dose to bile exteriorized rats, approximately 27% was excreted in the urine and 38% in the bile. Administration of (E)-2-ene increased bile flow rate, and the induced choleresis lasted for 3-4 h. (E)-2-ene VPA was largely excreted in apparently conjugated form in the urine and bile. The pharmacokinetics of (E)-2-ene VPA were similar to that of the parent drug VPA. PMID:2095402

Singh, K; Orr, J M; Abbott, F S

1990-10-01

290

Physical and functional interactions of human papillomavirus E2 protein with nuclear receptor coactivators  

SciTech Connect

In addition to the human papillomavirus (HPV)-induced immortalization of epithelial cells, which usually requires integration of the viral DNA into the host cell genome, steroid hormone-activated nuclear receptors (NRs) are thought to bind to specific DNA sequences within transcriptional regulatory regions on the long control region to either increase or suppress transcription of dependent genes. In this study, our data suggest that the NR coactivator function of HPV E2 proteins might be mediated through physical and functional interactions with not only NRs but also the NR coactivators GRIP1 (glucocorticoid receptor-interacting protein 1) and Zac1 (zinc-finger protein which regulates apoptosis and cell cycle arrest 1), reciprocally regulating their transactivation activities. GRIP1 and Zac1 both were able to act synergistically with HPV E2 proteins on the E2-, androgen receptor-, and estrogen receptor-dependent transcriptional activation systems. GRIP1 and Zac1 might selectively function with HPV E2 proteins on thyroid receptor- and p53-dependent transcriptional activation, respectively. Hence, the transcriptional function of E2 might be mediated through NRs and NR coactivators to regulate E2-, NR-, and p53-dependent transcriptional activations.

Wu, M.-H. [Graduate Institute of Life Sciences, National Defense Medical Center, Taipei City 114, Taiwan (China); Huang, C.-J. [Molecular Genetics and Biochemistry Laboratory, Cathay Medical Research Institute, Cathay General Hospital, Taipei County 221, Taiwan (China); Department of Biochemistry, National Defense Medical Center, Taipei City 114, Taiwan (China); Liu, S.-T. [Department of Biochemistry, National Defense Medical Center, Taipei City 114, Taiwan (China); Liu, P.-Y. [Graduate Institute of Life Sciences, National Defense Medical Center, Taipei City 114, Taiwan (China); Ho, C.-L. [Division of Hematology/Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei City 114, Taiwan (China); Huang, S.-M. [Graduate Institute of Life Sciences, National Defense Medical Center, Taipei City 114, Taiwan (China) and Department of Biochemistry, National Defense Medical Center, Taipei City 114, Taiwan (China)]. E-mail: shihming@ndmctsgh.edu.tw

2007-05-11

291

The HPV E2-Host Protein-Protein Interactions: A Complex Hijacking of the Cellular Network  

PubMed Central

Over 100 genotypes of human papillomaviruses (HPVs) have been identified as being responsible for unapparent infections or for lesions ranging from benign skin or genital warts to cancer. The pathogenesis of HPV results from complex relationships between viral and host factors, driven in particular by the interplay between the host proteome and the early viral proteins. The E2 protein regulates the transcription, the replication as well as the mitotic segregation of the viral genome through the recruitment of host cell factors to the HPV regulatory region. It is thereby a pivotal factor for the productive viral life cycle and for viral persistence, a major risk factor for cancer development. In addition, the E2 proteins have been shown to engage numerous interactions through which they play important roles in modulating the host cell. Such E2 activities are probably contributing to create cell conditions appropriate for the successive stages of the viral life cycle, and some of these activities have been demonstrated only for the oncogenic high-risk HPV. The recent mapping of E2-host protein-protein interactions with 12 genotypes representative of HPV diversity has shed some light on the large complexity of the host cell hijacking and on its diversity according to viral genotypes. This article reviews the functions of E2 as they emerge from the E2/host proteome interplay, taking into account the large-scale comparative interactomic study.

Muller, Mandy; Demeret, Caroline

2012-01-01

292

E2F1 has both oncogenic and tumor-suppressive properties in a transgenic model.  

PubMed

Using a transgenic mouse model expressing the E2F1 gene under the control of a keratin 5 (K5) promoter, we previously demonstrated that increased E2F1 activity can promote tumorigenesis by cooperating with either a v-Ha-ras transgene to induce benign skin papillomas or p53 deficiency to induce spontaneous skin carcinomas. We now report that as K5 E2F1 transgenic mice age, they are predisposed to develop spontaneous tumors in a variety of K5-expressing tissues, including the skin, vagina, forestomach, and odontogenic epithelium. On the other hand, K5 E2F1 transgenic mice are found to be resistant to skin tumor development following a two-stage carcinogenesis protocol. Additional experiments suggest that this tumor-suppressive effect of E2F1 occurs at the promotion stage and may involve the induction of apoptosis. These findings demonstrate that increased E2F1 activity can either promote or inhibit tumorigenesis, dependent upon the experimental context. PMID:10454586

Pierce, A M; Schneider-Broussard, R; Gimenez-Conti, I B; Russell, J L; Conti, C J; Johnson, D G

1999-09-01

293

Structure of a RING E3 ligase and ubiquitin-loaded E2 primed for catalysis.  

PubMed

Ubiquitin modification is mediated by a large family of specificity determining ubiquitin E3 ligases. To facilitate ubiquitin transfer, RING E3 ligases bind both substrate and a ubiquitin E2 conjugating enzyme linked to ubiquitin via a thioester bond, but the mechanism of transfer has remained elusive. Here we report the crystal structure of the dimeric RING domain of rat RNF4 in complex with E2 (UbcH5A) linked by an isopeptide bond to ubiquitin. While the E2 contacts a single protomer of the RING, ubiquitin is folded back onto the E2 by contacts from both RING protomers. The carboxy-terminal tail of ubiquitin is locked into an active site groove on the E2 by an intricate network of interactions, resulting in changes at the E2 active site. This arrangement is primed for catalysis as it can deprotonate the incoming substrate lysine residue and stabilize the consequent tetrahedral transition-state intermediate. PMID:22842904

Plechanovová, Anna; Jaffray, Ellis G; Tatham, Michael H; Naismith, James H; Hay, Ronald T

2012-09-01

294

A SMALL MOLECULE E2F INHIBITOR BLOCKS GROWTH IN A MELANOMA CULTURE MODEL  

PubMed Central

HLM006474 was identified using a computer-based virtual screen and the known crystal structure of the DNA bound E2F4/DP2 heterodimer. Treatment of multiple cell lines with HLM006474 resulted in the loss of intracellular E2F4 DNA-binding activity as measured by electrophoretic mobility shift assay within hours. Overnight exposure to HLM006474 resulted in down regulation of total E2F4 protein as well as known E2F targets. The effects of HLM006474 treatment on different cell lines varied, but included a reduction in cell proliferation and an increase in apoptosis. HLM006474 induced apoptosis in a manner distinct from cisplatin and doxorubicin. E2F4-null MEFs were less sensitive than wildtype counterparts to the apoptosis-inducing activity of the compound revealing its biological specificity. A375 cells were extremely sensitive to the apoptosis-inducing activity of the compound in two-dimensional culture and HLM006474 was a potent inhibitor of melanocytes proliferation and subsequent invasion in a three-dimensional tissue culture model system. Together, these results suggest that interference with E2F activity using small molecules may have clinical application in cancer therapy.

Ma, Yihong; Kurtyka, Courtney A.; Boyapalle, Sandhya; Sung, Shen-Shu; Lawrence, Harshani; Guida, Wayne; Cress, W. Douglas

2013-01-01

295

Baculovirus expression and antigenic characterization of classical swine fever virus E2 proteins.  

PubMed

Genes encoding a major structural glycoprotein, E2, of classical swine fever viruses (CSFV) Brescia (subgroup 1.2), Paderborn (subgroup 2.1) and Kanagawa (subgroup 3.4) were constructed by removing the transmembrane domain and adding a C-terminal 6 histidine (His) tag. All the E2 constructs were efficiently expressed in a baculovirus system as 53-kDa glycosylated proteins that were identified in Western blots by their reaction with anti-His and CSFV-specific antibodies. These proteins were used as ELISA antigens to confirm the existence of an antigenic relationship between the viruses using group-specific polyclonal antisera. Antigenic differences were identified by Western blot and ELISA reactivity of the E2 proteins with a panel of monoclonal antibodies. Specifically, one monoclonal antibody (WH303) reacted with all three proteins, two monoclonal antibodies (M1660 and M1665) reacted with only the Brescia E2 protein, and three monoclonal antibodies (M1654, M1664 and M1669) reacted equally well with only Brescia and Kanagawa E2 proteins. Therefore, antibody reactivity profiles, established using recombinant E2 proteins, could be used to quickly identify novel CSFV strains as illustrated in this report with only a limited number of monoclonal antibodies. These proteins could also have added utility in the production of monoclonal antibodies and as critical reagents in diagnostic assays. PMID:22510427

Luo, L; Nishi, K; Macleod, E; Sabara, M I; Lin, M; Handel, K; Pasick, J

2012-04-18

296

Selective recruitment of an E2~ubiquitin complex by an E3 ubiquitin ligase.  

PubMed

RING E3 ligases are proteins that must selectively recruit an E2-conjugating enzyme and facilitate ubiquitin transfer to a substrate. It is not clear how a RING E3 ligase differentiates a naked E2 enzyme from the E2?ubiquitin-conjugated form or how this is altered upon ubiquitin transfer. RING-box protein 1 (Rbx1/ROC1) is a key protein found in the Skp1/Cullin-1/F-box (SCF) E3 ubiquitin ligase complex that functions with the E2 ubiquitin conjugating enzyme CDC34. The solution structure of Rbx1/ROC1 revealed a globular RING domain (residues 40-108) stabilized by three structural zinc ions (root mean square deviation 0.30 ± 0.04 ?) along with a disordered N terminus (residues 12-39). Titration data showed that Rbx1/ROC1 preferentially recruits CDC34 in its ubiquitin-conjugated form and favors this interaction by 50-fold compared with unconjugated CDC34. Furthermore, NMR and biochemical assays identified residues in helix ?2 of Rbx1/ROC1 that are essential for binding and activating CDC34?ubiquitin for ubiquitylation. Taken together, this work provides the first direct structural and biochemical evidence showing that polyubiquitylation by the RING E3 ligase Rbx1/ROC1 requires the preferential recruitment of an E2?ubiquitin complex and subsequent release of the unconjugated E2 protein upon ubiquitin transfer to a substrate or ubiquitin chain. PMID:22433864

Spratt, Donald E; Wu, Kenneth; Kovacev, Jordan; Pan, Zhen-Qiang; Shaw, Gary S

2012-03-20

297

E2F1-3 Switch from Activators in Progenitor Cells to Repressors in Differentiating Cells  

PubMed Central

In the classic paradigm of mammalian cell cycle control, Rb functions to restrict cells from entering S phase by sequestering E2F activators (E2f1, E2f2 and E2f3), which are invariably portrayed as the ultimate effectors of a transcriptional program that commit cells to enter and progress through S phase1, 2. Using a panel of tissue-specific cre-transgenic mice and conditional E2f alleles we examine the effects of E2f1, E2f2 and E2f3 triple deficiency in murine ES cells, embryos and small intestines. We show that in normal dividing progenitor cells E2F1-3 function as transcriptional activators, but contrary to current dogma, are dispensable for cell division and instead are necessary for cell survival. In differentiating cells they function in complex with Rb as repressors to silence E2F targets and facilitate exit from the cell cycle. The inactivation of Rb in differentiating cells resulted in a switch of E2F1-3 from repressors to activators, leading to the superactivation of E2F responsive targets and ectopic cell divisions, and loss of E2f1-3 completely suppressed these phenotypes. This work contextualizes the activator versus repressor functions of E2F1-3 in vivo, revealing distinct roles in dividing versus differentiating cells and in normal versus cancer-like cell cycles in vivo.

Chong, Jean-Leon; Wenzel, Pamela L.; Saenz-Robles, M. Teresa; Nair, Vivek; Ferrey, Antoney; Hagan, John P.; Gomez, Yorman M.; Sharma, Nidhi; Chen, Hui-Zi; Ouseph, Madhu; Wang, Shu-Huei; Trikha, Prashant; Culp, Brian; Mezache, Louise; Winton, Douglas J.; Sansom, Owen J.; Chen, Danian; Bremner, Rod; Cantalupo, Paul G.; Robinson, Michael L.; Pipas, James M.; Leone, Gustavo

2009-01-01

298

Efficient priming against classical swine fever with a safe glycoprotein E2 expressing Orf virus recombinant (ORFV VrV-E2)  

Microsoft Academic Search

An increasing demand in livestock animal husbandry for intervention or emergency vaccination strategies requires a rapid onset of protection linked to prevention of infectious agent spread. Using the new recombinant parapoxvirus (PPV) Orf virus (ORFV) as a vaccine expressing the CSFV E2 glycoprotein we demonstrate that a single intra-muscular application confers solid protection. In the prime only concept, multi-site application

Heiner Voigt; Catherine Merant; Daniel Wienhold; Angelika Braun; Evelyne Hutet; Marie-Frédérique Le Potier; Armin Saalmüller; Eberhard Pfaff; Mathias Büttner

2007-01-01

299

The adenovirus E4 gene, in addition to the E1A gene, is important for trans-activation of E2 transcription and for E2F activation  

SciTech Connect

Previous experiments have demonstrated that adenovirus infection of human and mouse cells leads to an E1A-dependent activation of the DNA-binding capacity of a cellular transcription factor termed E2F. E2F binds to two sites in the adenovirus E2 early promoter which have been shown to be critical for E1A-dependent E2 early transcription, and the E2F-binding sites can confer E1A-induced transcription to a heterologous promoter. In addition, under a variety of circumstances, the increase in E2F-binding activity coincides with the activation of E2 transcription. The authors now find that, in addition to the E1A gene, another early viral gene, the E4 gene, is necessary for the activation of E2F-binding activity. Extracts prepared from human 293 cells, which express the E1A and E1B genes, had low levels of E2F activity, whereas infection of 293 cells with the E1A mutant dl312 increased E2F activity. A coinfection with the two mutants yielded the normal wild-type increase in E2F. Furthermore, infection of HeLa cells with a high multiplicity of dl312 did not yield an increase in E2F activity. Thus, it appears that both the E1A gene and the E4 gene are directly involved in E2F activation. Measurements of E2 RNA production in a dl366 infection as compared with a wild-type or dl312 infection demonstrate that the E4 gene is essential for full E2 transcription. They conclude that the activation of the E2F factor leading to the activation of E2 transcription requires the combined action of both the E1A 289-amino-acid protein and an E4 product.

Reichel, R.; Neill, S.D.; Kovesdi, I.; Simon, M.C.; Raychaudhuri, P.; Nevins, J.R. (Duke Univ. Medical Center, Durham, NC (USA))

1989-09-01

300

Prolactin and aging: X-irradiated and estrogen-induced rat mammary tumorigenesis  

SciTech Connect

Both sexes of inbred WF rats at either 8 or 28-60 weeks of age were exposed to 200 rad whole-body radiation, 2.5 or 5.0 mg 17 beta-estradiol (E2), or both agents The female rats treated with E2 alone or with both X-rays and E2 at 8 weeks of age showed a high incidence of mammary carcinomas (MCA), a large increase in pituitary weight, and a rise in serum prolactin (PRL) levels. However, the same treatments to males did not induce MCA despite a moderate increase in both pituitary weight and serum PRL. Ovariectomy prior to E2 treatment failed to modify the occurrence of MCA or pituitary tumors. When X-rays and E2 were given to female rats at 28-60 weeks of age, pituitary weight, serum PRL levels, and the incidence of MCA were unaffected. When the E2 pellet was kept for the first 24 weeks and withdrawn during the last 12 weeks, the incidence of MCA, pituitary weight, and serum PRL was low. It was concluded that: 1) the pituitary glands of young female rats were susceptible to E2 treatment but were insensitive in older females, and 2) the occurrence of MCA in female rats appeared to be promoted by elevated PRL levels secreted by E2-induced pituitary tumors. Mammary tissue of male rats was less sensitive to PRL levels in the development of MCA.

Ito, A.; Naito, M.; Watanabe, H.; Yokoro, K.

1984-07-01

301

Dietary boron supplementation enhanced the action of estrogen, but not that of parathyroid hormone, to improve trabecular bone quality in ovariectomized rats.  

PubMed

This study investigated whether boron would enhance the ability of 17beta-estradiol (E2) or parathyroid hormone (PTH) to improve bone quality in ovariectomized OVX rats. Adult OVX rats were treated for 5 wk with vehicle, boron (5 ppm as boric acid), E2 (30 microg/kg/d, sc), PTH (60 microg/kg/d, sc), or a combination of boron and E2 or PTH, respectively. The E2 treatment corrected many adverse effects of OVX on bone quality, increased bone Ca, P, and Mg contents, and decreased trabecular plate separation. Dietary boron supplementation had no effects on these bone parameters in OVX rats. When OVX rats were treated with boron and E2 together, trabecular bone volume (Tb.BS/TV) and plate density were increased significantly more than that caused by E2 alone. The boron and E2 combination also increased trabecular bone surface (Tb.BV/TV) and decreased trabecular plate separation in OVX rats. In contrast, whereas daily PTH injection also increased bone Ca, Mg, and P contents, Tb.BV/TV, Tb.BS/TV, trabecular plate density and thickness, and decreased trabecular plate separation in OVX rats, the combination of boron and PTH had no additional improvement in bone quality over that achieved by PTH alone. In summary, this study shows for the first time that boron enhanced the action of E2, but not that of PTH, to improve trabecular bone quality in OVX rats. PMID:11697760

Sheng, M H; Taper, L J; Veit, H; Qian, H; Ritchey, S J; Lau, K H

2001-01-01

302

Usability of Fag e 2 ImmunoCAP in the diagnosis of buckwheat allergy.  

PubMed

Currently, the detection of crude buckwheat extract-specific IgE by ImmunoCAP (f11) (Phadia AB, Uppsala, Sweden) is widely used to diagnose buckwheat allergy. However, the results of this test do not always correlate with the development of allergic symptoms. This study aimed to evaluate the diagnostic usefulness of specific IgE antibody titers for the major buckwheat allergens Fag e 1 and Fag e 2. Specific IgE antibodies were determined using the ImmunoCAP method for native Fag e 1 and Fag e 2, recombinant Fag e 1 and Fag e 2, and crude buckwheat extract (f11) in 10 buckwheat allergy patients, 14 atopic dermatitis patients, and 15 healthy subjects. All buckwheat allergy patients showed positive results for native Fag e 1- and Fag e 2-specific IgE tests and for ImmunoCAP (f11). In contrast, the rates of atopic dermatitis patients with positive results for native Fag e 1- and Fag e 2-specific IgE tests were 64.2% (9/14) and 57.1% (8/14), respectively. The sensitivities of the test using recombinant proteins were lower than those of the test using native proteins. The area under the curve (AUC) as determined by receiver operating characteristic (ROC) curve analysis was the largest for the native Fag e 2-specific IgE test (0.967), with a sensitivity of 90% and a specificity of 89.6% (cut-off: 2.74 kUa/L). Thus, the native Fag e 2-specific IgE antibody titer obtained using the ImmunoCAP method is more reliable than the buckwheat ImmunoCAP (f11) value for predicting buckwheat allergy. PMID:21461893

Tohgi, Kimiko; Kohno, Kunie; Takahashi, Hitoshi; Matsuo, Hiroaki; Nakayama, Satoshi; Morita, Eishin

2011-04-03

303

Glucocorticoid regulation of branched-chain alpha-ketoacid dehydrogenase E2 subunit gene expression.  

PubMed Central

Regulation of the mammalian branched-chain alpha-ketoacid dehydrogenase complex (BCKAD) occurs under a variety of stressful conditions associated with changes in circulating glucocorticoids. Multiple levels of regulation in hepatocytes, including alteration of the levels of the structural subunits available for assembly (E1, alpha-ketoacid decarboxylase; E2, dihydrolipoamide acyltransferase; and E3, dihydrolipoamide dehydrogenase), as well as BCKAD kinase, which serves to phosphorylate the E1alpha subunit and inactivate complex activity, have been proposed. The direct role of glucocorticoids in regulating the expression of the murine gene encoding the major BCKAD subunit E2, upon which the other BCKAD subunits assemble, was therefore examined. Deletion analysis of the 5' proximal 7.0 kb of the murine E2 promoter sequence, using E2 promoter/luciferase expression minigene plasmids introduced into the hepatic H4IIEC3 cell line, suggested a promoter proximal region responsive to glucocorticoid regulation. Linker-scanning mutagenesis combined with deletion analysis established this functional glucocorticoid-responsive unit (GRU) to be located near the murine E2 proximal promoter site at -140 to -70 bp upstream from the transcription initiation site. The presence of this region in plasmid minigenes, containing varying amounts of the murine genomic sequence 5' upstream from proximal E2 promoter sequences, conferred 2-10 fold increases in luciferase reporter gene expression in H4IIEC3 cells, whether introduced by transient transfection or following co-selection for stable transfectants. The GRU region itself appeared to contain multiple interacting elements that combine to regulate overall E2 promoter activity in response to changing physiological conditions associated with varying concentrations of glucocorticoids and likely other hormonal effectors.

Costeas, P A; Chinsky, J M

2000-01-01

304

Characterization of hepatitis C virus recombinants with chimeric E1/E2 envelope proteins and identification of single amino acids in the E2 stem region important for entry.  

PubMed

The hepatitis C virus (HCV) envelope proteins E1 and E2 play a key role in host cell entry and represent important targets for vaccine and drug development. Here, we characterized HCV recombinants with chimeric E1/E2 complexes in vitro. Using genotype 1a/2a JFH1-based recombinants expressing 1a core-NS2, we exchanged E2 with functional isolate sequences of genotypes 1a (alternative isolate), 1b, and 2a. While the 1a-E2 exchange did not impact virus viability, the 2a-E2 recombinant was nonviable. After E2 exchange from three 1b isolates, long delays were observed before spread of infection. For recovered 1b-E2 recombinants, single E2 stem region amino acid changes were identified at residues 706, 707, and 710. In reverse genetic studies, these mutations increased infectivity titers by ~100-fold, apparently without influencing particle stability or cell binding although introducing slight decrease in particle density. In addition, the 1b-E2 exchange led to a decrease in secreted core protein of 25 to 50%, which was further reduced by the E2 stem region mutations. These findings indicated that compensatory mutations permitted robust infectious virus production, without increasing assembly/release. Studies of E1/E2 heterodimerization showed no differences in intracellular E1/E2 interaction for chimeric constructs with or without E2 stem region mutations. Interestingly, the E2 stem region mutations allowed efficient entry, which was verified in 1a-E1/1b-E2 HCV pseudoparticle assays. A CD81 inhibition assay indicated that the mutations influenced a late step of the HCV entry pathway. Overall, this study identified specific amino acids in the E2 stem region of importance for HCV entry and for production of infectious virus particles. PMID:23152512

Carlsen, Thomas H R; Scheel, Troels K H; Ramirez, Santseharay; Foung, Steven K H; Bukh, Jens

2012-11-14

305

Identification of E2F1 as a positive transcriptional regulator for {delta}-catenin  

SciTech Connect

{delta}-Catenin is upregulated in human carcinomas. However, little is known about the potential transcriptional factors that regulate {delta}-catenin expression in cancer. Using a human {delta}-catenin reporter system, we have screened several nuclear signaling modulators to test whether they can affect {delta}-catenin transcription. Among {beta}-catenin/LEF-1, Notch1, and E2F1, E2F1 dramatically increased {delta}-catenin-luciferase activities while {beta}-catenin/LEF-1 induced only a marginal increase. Rb suppressed the upregulation of {delta}-catenin-luciferase activities induced by E2F1 but did not interact with {delta}-catenin. RT-PCR and Western blot analyses in 4 different prostate cancer cell lines revealed that regulation of {delta}-catenin expression is controlled mainly at the transcriptional level. Interestingly, the effects of E2F1 on {delta}-catenin expression were observed only in human cancer cells expressing abundant endogenous {delta}-catenin. These studies identify E2F1 as a positive transcriptional regulator for {delta}-catenin, but further suggest the presence of strong negative regulator(s) for {delta}-catenin in prostate cancer cells with minimal endogenous {delta}-catenin expression.

Kim, Kwonseop [Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, 600 Moye Street, Greenville, NC 27834 (United States); College of Pharmacy and Research Institute of Drug development, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Oh, Minsoo; Ki, Hyunkyoung [College of Pharmacy and Research Institute of Drug development, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Wang Tao; Bareiss, Sonja [Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, 600 Moye Street, Greenville, NC 27834 (United States); Fini, M. Elizabeth. [Bascom Palmer Eye Institute, Miller School of Medicine, University of Miami, Miami, FL 33136 (United States); Li Dawei [Department of Pathology, Harvard Medical School, Boston, MA 20115 (United States); Lu Qun [Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, 600 Moye Street, Greenville, NC 27834 (United States)], E-mail: luq@ecu.edu

2008-05-02

306

Functional Selection of Hepatitis C Virus Envelope E2-Binding Peptide Ligands by Using Ribosome Display ?  

PubMed Central

Small peptides that inhibit the hepatitis C virus (HCV) at the stage of viral entry have the potential to serve as attractive antiviral drugs. Ribosome display is a cell-free system for in vitro selection of peptides from large random peptide libraries. Thus, we utilized a ribosome display library technique for affinity selection of HCV envelope protein E2-binding peptide ligands. Through 13 rounds of selection, the ribosome display system generated high-affinity 12-mer peptides, and the selected peptide PE2D (MARHRNWPLVMV) demonstrated the highest specificity and affinity to the HCV E2 protein. Furthermore, amino acids 489 to 508 (YPPRPCGIVPAKSVCGPVYC) of E2 were identified as crucial for binding to PE2D. The selected peptides, especially PE2D, not only dramatically blocked E2 protein binding to hepatocytes but also dramatically inhibited HCV cell culture (HCVcc) entry into hepatocytes. HCVcc and HCV particles from HCV patient serum samples could also be specifically captured using PE2D. Our study demonstrates that the newly selected peptide ligand PE2D holds great promise for developing a new molecular probe, a therapeutic drug specifically for HCV, or an early-diagnostic reagent for HCV surface envelope antigen E2.

Chen, Fang; Zhao, Yinglan; Liu, Min; Li, Dongqing; Wu, Hongyan; Chen, Haidan; Zhu, Yongzhe; Luo, Fengling; Zhong, Jin; Zhou, Yidan; Qi, Zhongtian; Zhang, Xiao-Lian

2010-01-01

307

Allosteric regulation of E2:E3 interactions promote a processive ubiquitination machine.  

PubMed

RING finger proteins constitute the large majority of ubiquitin ligases (E3s) and function by interacting with ubiquitin-conjugating enzymes (E2s) charged with ubiquitin. How low-affinity RING-E2 interactions result in highly processive substrate ubiquitination is largely unknown. The RING E3, gp78, represents an excellent model to study this process. gp78 includes a high-affinity secondary binding region for its cognate E2, Ube2g2, the G2BR. The G2BR allosterically enhances RING:Ube2g2 binding and ubiquitination. Structural analysis of the RING:Ube2g2:G2BR complex reveals that a G2BR-induced conformational effect at the RING:Ube2g2 interface is necessary for enhanced binding of RING to Ube2g2 or Ube2g2 conjugated to Ub. This conformational effect and a key ternary interaction with conjugated ubiquitin are required for ubiquitin transfer. Moreover, RING:Ube2g2 binding induces a second allosteric effect, disrupting Ube2g2:G2BR contacts, decreasing affinity and facilitating E2 exchange. Thus, gp78 is a ubiquitination machine where multiple E2-binding sites coordinately facilitate processive ubiquitination. PMID:23942235

Das, Ranabir; Liang, Yu-He; Mariano, Jennifer; Li, Jess; Huang, Tao; King, Aaren; Tarasov, Sergey G; Weissman, Allan M; Ji, Xinhua; Byrd, R Andrew

2013-08-13

308

Identification of conjugation specificity determinants unmasks vestigial preference for ubiquitin within the NEDD8 E2.  

PubMed

Ubiquitin-like proteins (UBLs) modify targets via related E1-E2-E3 cascades. How is UBL conjugation fidelity established? Here we report the basis for UBL selection by UBL conjugating enzyme 12 (Ubc12), which is specific for the neural precursor cell expressed, developmentally down-regulated protein 8 (NEDD8), and does not form a thioester-linked conjugate with ubiquitin. We systematically identified Ubc12 surfaces impeding Ubc12 approximately ubiquitin conjugate formation and found that several structurally dispersed E1 binding elements, rather than UBL-interacting surfaces, determine E2 approximately UBL specificity. In addition to roles for conserved E1 and E2 domains, unique structures contribute UBL specificity to the NEDD8 and ubiquitin pathways. By removing surface elements, without substituting corresponding sequences from ubiquitin E2s, we unmasked Ubc12's vestigial preference for ubiquitin over NEDD8 by approximately 10(10)-fold. This has implications for the evolution of specific functions among ubiquitin E2s. We also find that Ubc12 sequences dictating UBL selection map to the E3 binding site, thus providing a molecular mechanism preventing inappropriate modification of targets. PMID:18264111

Huang, Danny T; Zhuang, Min; Ayrault, Olivier; Schulman, Brenda A

2008-02-10

309

E2-RING expansion of the NEDD8 cascade confers specificity to cullin modification  

SciTech Connect

Ubiquitin and ubiquitin-like proteins (UBLs) are directed to targets by cascades of E1, E2, and E3 enzymes. The largest ubiquitin E3 subclass consists of cullin-RING ligases (CRLs), which contain one each of several cullins (CUL1, -2, -3, -4, or -5) and RING proteins (RBX1 or -2). CRLs are activated by ligation of the UBL NEDD8 to a conserved cullin lysine. How is cullin NEDD8ylation specificity established? Here we report that, like UBE2M (also known as UBC12), the previously uncharacterized E2 UBE2F is a NEDD8-conjugating enzyme in vitro and in vivo. Biochemical and structural analyses indicate how plasticity of hydrophobic E1-E2 interactions and E1 conformational flexibility allow one E1 to charge multiple E2s. The E2s have distinct functions, with UBE2M/RBX1 and UBE2F/RBX2 displaying different target cullin specificities. Together, these studies reveal the molecular basis for and functional importance of hierarchical expansion of the NEDD8 conjugation system in establishing selective CRL activation.

Huang, D.T.; Ayrault, O.; Hunt, H.W.; Taherbhoy, A.M.; Duda, D.M.; Scott, D.C.; Borg, L.A.; Neale, G.; Murray, P.J.; Roussel, M.F.; Schulman, B.A.; (SJCH)

2009-03-27

310

Membrane-initiated actions of estradiol (E2) in the regulation of LH secretion in ovariectomized (OVX) ewes  

PubMed Central

Background We demonstrated that E2 conjugated to BSA (E2BSA) induces a rapid membrane-initiated inhibition of LH secretion followed hours later by a slight increase in LH secretion. Whether these actions of E2BSA are restricted to the pituitary gland and whether the membrane-initiated pathway of E2BSA contributes to the up-regulation of the number of GnRH receptors during the positive feedback effect of E2 were evaluated here. We have shown that the suppression of LH secretion induced by E2 and E2BSA is the result of a decreased responsiveness of the pituitary gland to GnRH. In this study we further tested the ability of E2BSA to decrease the responsiveness of the pituitary gland to GnRH under the paradigm of the preovulatory surge of LH induced by E2. Methods For the first experiment GnRH and LH secretions were determined in samples of pituitary portal and jugular blood, respectively, in ewes treated with 12 mg E2BSA. In the second experiment, the number of GnRH receptors was quantified in ewes 12 h after administration of 25 micrograms E2 (the expected time for the increase in the number of GnRH receptors and the positive feedback effect of E2 in LH secretion) or 12 mg E2BSA. In the third experiment, the preovulatory-like surge of LH was characterized in ewes injected with 25 micrograms E2 alone or followed 8 h later (before the beginning of the LH surge) with 60 mg E2BSA. Results a) the decrease in LH secretion induced by E2BSA was not accompanied by changes in the pulsatile pattern of GnRH, b) E2BSA increased the number of GnRH receptors, and c) the presence of E2BSA in E2-treated ewes delayed the onset, reduced the length, and decreased the amount of LH released during the preovulatory surge of LH. Conclusions a) the rapid suppression of LH secretion induced by E2BSA is mediated only via a direct action on the pituitary gland, b) E2 acting via a membrane-initiated pathway contributes to increase the number of GnRH receptors and, c) administration of E2BSA near the beginning of the pre-ovulatory surge of LH delays and reduces the magnitude of the surge.

2010-01-01

311

Small interfering RNA targeting bovine papillomavirus type 1 E2 induces apoptosis in equine sarcoid transformed fibroblasts  

Microsoft Academic Search

Equine sarcoids are skin tumours of horses caused by infection with BPV-1 or 2. Maintenance and replication of the viral genome depend upon the viral proteins E1 and E2. We examined the effects of an E2 specific siRNA on E2 and E1 viral gene expression, viral load and cell growth in BPV-1 transformed sarcoid-derived cells. Transfection with E2-siRNA caused a

Philipe A. M. Gobeil; ZhengQiang Yuan; Elizabeth A. Gault; Iain M. Morgan; M. Saveria Campo; Lubna Nasir

2009-01-01

312

LISA Pathfinder E2E performance simulation: optical and self-gravity stability analysis  

NASA Astrophysics Data System (ADS)

End-to-end (E2E) modelling and simulation, i.e. verifying the science performance of LISA Pathfinder (spacecraft and payload), is mandatory in order to minimize mission risks. In this paper, focus is on two particular applications of the E2E performance simulator currently being developed at EADS Astrium GmbH: the opto-dynamical stability and the self-gravity disturbance stability analysis. The E2E models applied here comprise the opto-dynamical modelling of the optical metrology systems (OMS) laser interferometry, the thermo-elastic distortion modelling of the OMS optical elements and the self-gravity disturbance model accounting for structural distortions. Preliminary analysis results are presented in detail, identifying shortcomings of the current LISA technology package (LTP) mounting baseline. As a consequence, the design is now being revised.

Brandt, N.; Fichter, W.; Kersten, M.; Lucarelli, S.; Montemurro, F.

2005-05-01

313

HEB and E2A function as SMAD/FOXH1 cofactors  

PubMed Central

Nodal signaling, mediated through SMAD transcription factors, is necessary for pluripotency maintenance and endoderm commitment. We identified a new motif, termed SMAD complex-associated (SCA), that is bound by SMAD2/3/4 and FOXH1 in human embryonic stem cells (hESCs) and derived endoderm. We demonstrate that two basic helix–loop–helix (bHLH) proteins—HEB and E2A—bind the SCA motif at regions overlapping SMAD2/3 and FOXH1. Furthermore, we show that HEB and E2A associate with SMAD2/3 and FOXH1, suggesting they form a complex at critical target regions. This association is biologically important, as E2A is critical for mesendoderm specification, gastrulation, and Nodal signal transduction in Xenopus tropicalis embryos. Taken together, E proteins are novel Nodal signaling cofactors that associate with SMAD2/3 and FOXH1 and are necessary for mesendoderm differentiation.

Yoon, Se-Jin; Wills, Andrea E.; Chuong, Edward; Gupta, Rakhi; Baker, Julie C.

2011-01-01

314

Effect of Igniter Gases on Wear-Reducing Additive in the 155mm XM201E2 Propelling Charge.  

National Technical Information Service (NTIS)

The wear-reducing liner in the base-ignited XM201E2 charge failed to reduce the erosivity of the XM201E2 charge. When the clean-burning igniter (CBI) in the XM201E2 charge was replaced by black powder, the barrel life of 155mm howitzers firing the modifie...

J. R. Ward K. J. White

1978-01-01

315

Arabidopsis E2FA stimulates proliferation and endocycle separately through RBR-bound and RBR-free complexes  

PubMed Central

Post-embryonic growth in plants depends on the continuous supply of undifferentiated cells within meristems. Proliferating cells maintain their competence for division by active repression of differentiation and the associated endocycle entry. We show by upregulation and downregulation of E2FA that it is required for maintaining proliferation, as well as for endocycle entry. While E2FB–RBR1 (retinoblastoma-related protein 1) complexes are reduced after sucrose addition or at elevated CYCD3;1 levels, E2FA maintains a stable complex with RBR1 in proliferating cells. Chromatin immunoprecipitation shows that RBR1 binds in the proximity of E2F promoter elements in CCS52A1 and CSS52A2 genes, central regulators for the switch from proliferation to endocycles. Overexpression of a truncated E2FA mutant (E2FA?RB) lacking the RBR1-binding domain interferes with RBR1 recruitment to promoters through E2FA, leading to decreased meristem size in roots, premature cell expansion and hyperactivated endocycle in leaves. E2F target genes, including CCS52A1 and CCS52A2, are upregulated in E2FA?RB and e2fa knockout lines. These data suggest that E2FA in complex with RBR1 forms a repressor complex in proliferating cells to inhibit premature differentiation and endocycle entry. Thus, E2FA regulates organ growth via two distinct, sequentially operating pathways.

Magyar, Zoltan; Horvath, Beatrix; Khan, Safina; Mohammed, Binish; Henriques, Rossana; De Veylder, Lieven; Bako, Laszlo; Scheres, Ben; Bogre, Laszlo

2012-01-01

316

The Amyloid Precursor Protein (APP) Does Not Have a Ferroxidase Site in Its E2 Domain.  

PubMed

The ubiquitous 24-meric iron-storage protein ferritin and multicopper oxidases such as ceruloplasmin or hephaestin catalyze oxidation of Fe(II) to Fe(III), using molecular oxygen as oxidant. The ferroxidase activity of these proteins is essential for cellular iron homeostasis. It has been reported that the amyloid precursor protein (APP) also has ferroxidase activity. The activity is assigned to a ferroxidase site in the E2 domain of APP. A synthetic 22-residue peptide that carries the putative ferroxidase site of E2 domain (FD1 peptide) has been claimed to encompass the same activity. We previously tested the ferroxidase activity of the synthetic FD1 peptide but we did not observe any activity above the background oxidation of Fe(II) by molecular oxygen. Here we used isothermal titration calorimetry to study Zn(II) and Fe(II) binding to the natural E2 domain of APP, and we employed the transferrin assay and oxygen consumption measurements to test the ferroxidase activity of the E2 domain. We found that this domain neither in the presence nor in the absence of the E1 domain binds Fe(II) and it is not able to catalyze the oxidation of Fe(II). Binding of Cu(II) to the E2 domain did not induce ferroxidase activity contrary to the presence of redox active Cu(II) centers in ceruloplasmin or hephaestin. Thus, we conclude that E2 or E1 domains of APP do not have ferroxidase activity and that the potential involvement of APP as a ferroxidase in the pathology of Alzheimer's disease must be re-evaluated. PMID:23977245

Honarmand Ebrahimi, Kourosh; Dienemann, Christian; Hoefgen, Sandra; Than, Manuel E; Hagedoorn, Peter-Leon; Hagen, Wilfred R

2013-08-19

317

Building the Coolest X-Ray Satellite: Astro-E2 Teacher Guide  

NSDL National Science Digital Library

This teacher guide provides instructions for using the video - Building the Coolest X-ray Satellite: Astro-E2 - in the classroom. The video describes NASA's development of the X-ray Telescopes and X-ray Spectrometer for the Asro-E2 mission. The telescopes utilize grazing optics to focus X-rays, and the spectrometer determines the energy of an X-ray by measuring the temperature rise in a wafer due to an incident X-ray. The teachers guide includes discussion questions and activities related to the video content. Topics covered include science careers, optics, cryogenics, X-ray astronomy, and working on an international project.

2006-04-01

318

Molecular-frame (e,2e) experiment for N2 at large momentum transfer  

NASA Astrophysics Data System (ADS)

We report molecular-frame (e,2e) cross sections for N2 at large momentum transfer, obtained using the electron-electron-fragment ion triple-coincidence technique. The measured angular distribution of the (e,2e) cross section for the inner-valence 2?g orbital appears to show that the spatial character of the orbital has been directly observed in momentum space. On the other hand, experimental results for ionization to states above the double-ionization threshold suggested a larger intensity in the direction perpendicular to the molecular axis rather than parallel, an observation that our plane-wave impulse-approximation calculations fail to reproduce.

Jones, D. B.; Yamazaki, M.; Watanabe, N.; Takahashi, M.

2013-02-01

319

TGF{beta}-mediated formation of pRb-E2F complexes in human myeloid leukemia cells  

SciTech Connect

TGF{beta} is well known for its inhibitory effect on cell cycle G1 checkpoint kinases. However, its role in the control of pRb-E2F complexes is not well established. TGF{beta} inhibits phosphorylation of pRb at several serine and threonine residues and regulates the association of E2F transcription factors with pRb family proteins. Recent studies found that predominantly E2F-4, p130, and histone deacetylase (HDAC) are found to bind to corresponding E2F-responsive promoters in G0/G1 phase. As cells progress through mid-G1, p130-E2F4 complex are replaced by p107-E2F4 followed by activators E2F1, 2, and 3. pRb was not detectable in the promoters containing the E2F-responsive site in cycling cells but was associated with E2F4-p130 complexes or E2F4-p107 complexes during G0/G1 phase. In human myeloid leukemia cell line, MV4-11, TGF{beta} upregulated pRb-E2F-4 and p130-E2F-4, and downregulated p107-E2F-4 complexes. However, pRB-E2F1 and pRb-E2F3 complexes were found in proliferating cells but not in TGF{beta} arrested G1 cells. In addition, electrophoretic gel mobility shift assay (EMSA) could not detect pRb-E2F DNA-binding activities either in S or G1 phase but exhibited the existence of p107-E2F4 in proliferating cells and p130-E2F4 complexes in TGF{beta}-arrested G1 cells, respectively. Our data suggest that p107 and p130, but not pRb, and the repressor E2F, but not activator E2Fs, play a critical role in regulating E2F-responsive gene expression in TGF{beta}-mediated cell cycle control in human myeloid leukemia cells.

Hu Xiaotang [School of Natural and Health Science, Barry University, 11300 Northeast Second Avenue, Miami Shores, FL 33161 (United States)], E-mail: xthu@mail.barry.edu

2008-05-02

320

The role of E2F-1 and downstream target genes in mediating ischemia/reperfusion injury in vivo.  

PubMed

E2Fs are a family of transcription factors that regulate proliferation, differentiation and apoptosis in many cell types. E2F-1 is the prototypical E2F and the family member that has most often been implicated in also mediating apoptosis. To better understand the role of E2F-1 in mediating cardiomyocyte injury we initially analyzed E2F family member expression after ischemia/reperfusion (I/R) in vivo or simulated ischemia in vitro. I/R injury in vivo caused a 3.4-fold increase specifically in E2F-1 protein levels. Expression of other E2F family members did not change. To establish the role of E2F-1 in I/R we examined the response of germline deleted E2F-1 mice to I/R injury. Infarct size as a percentage of the area at risk was decreased 39.8% in E2F-1(-/-) mice compared to E2F-1(+/+) controls. Interestingly, expression of classic, E2F-1 apoptotic target genes was not altered in E2F-1 null cardiomyocytes after I/R. However, upregulation of the primary member of the Forkhead family of transcription factors, FoxO-1a, was attenuated. Consistent, with a role for FoxO-1a as an important target of E2F-1 in I/R, a number of proapoptotic FoxO-1a target genes were also altered. These results suggest that E2F-1 and FoxO-1a belong to a complex transcriptional network that may modulate myocardial cell death during I/R injury. PMID:21964190

Angelis, Ekaterini; Zhao, Peng; Zhang, Rui; Goldhaber, Joshua I; Maclellan, W Robb

2011-09-22

321

The Role of E2F-1 and Downstream Target Genes in Mediating Ischemia/Reperfusion Injury In Vivo  

PubMed Central

E2Fs are a family of transcription factors that regulate proliferation, differentiation and apoptosis in many cell types. E2F-1 is the prototypical E2F and the family member that has most often been implicated in also mediating apoptosis. To better understand the role of E2F-1 in mediating cardiomyocyte injury we initially analyzed E2F family member expression after ischemia/reperfusion (I/R) in vivo or simulated ischemia in vitro. I/R injury in vivo caused a 3.4-fold increase specifically in E2F-1 protein levels. Expression of other E2F family members did not change. To establish the role of E2F-1 in I/R we examined the response of germline deleted E2F-1 mice to I/R injury. Infarct size as a percentage of the area at risk was decreased 39.8% in E2F-1?/? mice compared to E2F-1+/+ controls. Interestingly, expression of classic, E2F-1 apoptotic target genes was not altered in E2F-1 null cardiomyocytes after I/R. However, upregulation of the primary member of the Forkhead family of transcription factors, FoxO-1a, was attenuated. Consistent, with a role for FoxO-1a as an important target of E2F-1 in I/R, a number of proapoptotic FoxO-1a target genes were also altered. These results suggest that E2F-1 and FoxO-1a belong to a complex transcriptional network that may modulate myocardial cell death during I/R injury.

Angelis, Ekaterini; Zhao, Peng; Zhang, Rui; Goldhaber, Joshua I.; MacLellan, W. Robb

2011-01-01

322

Estradiol facilitates neurite maintenance by a Src/Ras/ERK signalling pathway.  

PubMed

Different reports suggest the estrogens are involved in neuritic outgrowth, maintenance of dendritic morphology and spine formation in the CNS. However, the molecular mechanisms regulated by estrogens on neuronal integrity are not fully understood. We have addressed the relationship between 17beta-estradiol-dependent ERK pathway stimulation and the maintenance of neuritic morphology in cerebellar granule cell cultures (CGC). We report that 17beta-estradiol clearly activates ERK phosphorylation in CGC cultured in low potassium via ERalpha localized in the plasma membrane and without the activation of the insulin-like growth factor-I receptor. 17beta-estradiol activates the ERK pathway through Ras-dependent Src kinase activity. A concomitant activation of the cAMP-response element-binding protein (CREB) is observed. Moreover, we demonstrate that 17beta-estradiol-mediated ERK activation is involved in the maintenance of neuritic arborisation and neuronal morphology in proapoptotic conditions. PMID:18620059

Miñano, Alfredo; Xifró, Xavier; Pérez, Virgili; Barneda-Zahonero, Bruna; Saura, Carlos A; Rodríguez-Alvarez, José

2008-06-14

323

202. Using RNA to Inhibit Intimal Hperplasia by Blocking E2F Function  

Microsoft Academic Search

The six members of the E2F family of transcription factors are key players in the Rb tumor suppressor pathway leading to DNA replication and cell cycle control. The family members have both distinct and overlapping functions, and gaining an understanding of the roles each factor plays in the cell cycle will lead to a more precise understanding of the Rb

Alice K. Tanner; Joseph Nevins; Bruce Sullenger

2004-01-01

324

Ventromedial Preoptic Prostaglandin E2 Activates Fever-Producing Autonomic Pathways  

Microsoft Academic Search

Fever is thought to be initiated by pyrogenic cytokines inducing the production of prostaglandin E2 (PGE2) in the preoptic area (POA); PGE2 may act as a paracrine mediator that stimulates the neural pathways that raise body temperature. This essential role for prostaglandins in feverfirst was proposed 25 years ago, but the specific preoptic cell groups at which PGE2 acts and

Thomas E. Scammell; Joel K. Elmquist; John D. Griffin; Clifford B. Saper

325

Increased prostaglandin E 2 concentrations and cyclooxygenase-2 expression in asthmatic subjects with sputum eosinophilia  

Microsoft Academic Search

BackgroundProstaglandin E2 (PGE2) is known to be produced within human airways, but it is not clear whether in airway diseases it can play a deleterious or a beneficial role. Recently it has been reported that PGE2 can enhance eosinophil survival in vitro.

Mirella Profita; Angelo Sala; Anna Bonanno; Loredana Riccobono; Liboria Siena; Mario R Melis; Rossana Di Giorgi; Franco Mirabella; Mark Gjomarkaj; Giovanni Bonsignore; Antonio M Vignola

2003-01-01

326

Ellipsoidal corrections to order e 2 of geopotential coefficients and Stokes' formula  

Microsoft Academic Search

Assuming that the gravity anomaly and disturbing potential are given on a reference ellipsoid, the result of Sjöberg (1988, Bull Geod 62:93 101) is applied to derive the potential coefficients on the bounding sphere of the ellipsoid to order e 2 (i.e. the square of the eccentricity of the ellipsoid). By adding the potential coefficients and continuing the potential downward

L. E. Sjöberg

2003-01-01

327

Crystal structure of glycoprotein E2 from bovine viral diarrhea virus  

PubMed Central

Pestiviruses, including bovine viral diarrhea virus, are important animal pathogens and are closely related to hepatitis C virus, which remains a major global health threat. They have an outer lipid envelope bearing two glycoproteins, E1 and E2, required for cell entry. They deliver their genome into the host cell cytoplasm by fusion of their envelope with a cellular membrane. The crystal structure of bovine viral diarrhea virus E2 reveals a unique protein architecture consisting of two Ig-like domains followed by an elongated ?-stranded domain with a new fold. E2 forms end-to-end homodimers with a conserved C-terminal motif rich in aromatic residues at the contact. A disulfide bond across the interface explains the acid resistance of pestiviruses and their requirement for a redox activation step to initiate fusion. From the structure of E2, we propose alternative possible membrane fusion mechanisms. We expect the pestivirus fusion apparatus to be conserved in hepatitis C virus.

Li, Yue; Wang, Jimin; Kanai, Ryuta; Modis, Yorgo

2013-01-01

328

E2B(R3) Electronic Transmission of Individual Case Safety ...  

Center for Biologics Evaluation and Research (CBER)

Text VersionPage 1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 E2B(R3) Electronic Transmission of Individual Case Safety Reports (ICSRs) ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

329

Use of Prostaglandin E2 in the Management of Missed Abortion, Missed Labour, and Hydatidiform Mole  

Microsoft Academic Search

Treatment of six cases of missed abortion and one case of hydatidiform mole with intravenous infusion of prostaglandin E2 resulted in complete abortion in all cases. Of 15 patients with missed labour, 14 were delivered successfully with similar treatment. The technique appears to be a safe, reliable, and rapid method of managing missed abortion, missed labour, and hydatidiform mole.

S. M. M. Karim

1970-01-01

330

Production and characterization of mouse monoclonal antibodies reactive to Chikungunya envelope E2 glycoprotein.  

PubMed

Chikungunya fever is an arbovirosis of major impact in public health in Asia and Africa. Chikungunya (CHIK) virus is member of the genus Alphavirus and belongs to the Semliki Forest (SF) antigenic complex. We describe for the first time a panel of monoclonal antibodies (MAbs) reactive to CHIK envelope E2 glycoprotein. For the screening of E2-specific MAbs, we expressed a recombinant soluble CHIK E2 protein in Drosophila S2 cells. Analyzed by immunological methods, MAbs 3C3, 3E4, and 8A4 were selected on the basis of their reactivity. Their epitopes are located to the outer surface of CHIK virion. These MAbs have no cross reactivity with related members of SF antigenic complex with the notable exception of Igbo-Ora virus. Anti-CHIK E2 MAbs 3C3, 3E4, and 8A4 should be helpful for studying the biology of CHIK virus and pathogenesis of disease. The combination of 8A4 and 3E4 is suitable for developing a specific antigen-capture ELISA. PMID:17949772

Bréhin, Anne-Claire; Rubrecht, Laetitia; Navarro-Sanchez, Martha Erika; Maréchal, Valérie; Frenkiel, Marie-Pascale; Lapalud, Priscilla; Laune, Daniel; Sall, Amadou Alpha; Desprès, Philippe

2007-10-18

331

Prostaglandin E 2 release in keratinocyte cultures following exposure to various tumour promoters  

Microsoft Academic Search

The interaction of tumour promoters with the target cell type (keratinocyte) may be an essential feature of their promoting activity and their ability to initiate an inflammatory response. The role of prostaglandin E2 (PGE2), particularly in the keratinocyte, remains largely unknown, but it is closely associated with inflammation and regenerative epidermal hyperplasia, which appear critical for tumour promotion. Rat keratinocytes

J. N. Lawrence; D. J. Benford

1995-01-01

332

Highly protective E2-CSFV vaccine candidate produced in the mammary gland of adenoviral transduced goats.  

PubMed

Classical swine fever virus is the etiological agent of the most economically important highly contagious disease of swine worldwide. E2 is the major envelope glycoprotein present as a homodimer on the outer surface of the virus and represents an important target for the induction of neutralizing immune response against the viral infection. The E2 extracellular domain was expressed in the milk of adenoviral transduced goats at the highest level about 1.2g/L. The recombinant glycoprotein was purified from clarified serum milk by a single metal chelate affinity chromatography step, as a homodimer of approximately 100kDa and purity over 98%. Glycosylation analysis showed the presence of oligomannoside, hybrid and complex type N-glycans, attached to the recombinant E2. The capacity of goat milk-derived E2 antigen to protect pigs from both classical swine fever clinical signs and viral infection was assessed in a vaccination and challenge trial. The immunized pigs became protected after challenge with 10(5) LD(50) of a highly pathogenic CSFV strain. In the context of veterinary vaccines, this expression system has the advantages that the recombinant antigen could be harvested in about 48h after adenoviral transduction with expression levels in the range of g/L. This approach may turn into a scalable expression system for the assessment and production of veterinary vaccines. PMID:18045719

Toledo, Jorge R; Sánchez, Oliberto; Montesino, Raquel; Farnos, Omar; Rodríguez, Maria P; Alfonso, Pastor; Oramas, Nayrobis; Rodríguez, Elsa; Santana, Elaine; Vega, Ernesto; Ganges, Llilianne; Frias, Maria T; Cremata, José; Barrera, Maritza

2007-10-05

333

M1 and E2 emission lines in K-like ions (Charro+, 2002)  

NASA Astrophysics Data System (ADS)

Relativistic Quantum Defect Orbital (RQDO) calculations of transition probabilities for E2 (electric quadrupole) and M1 (magnetic dipole) forbidden transition in the potassium sequence have been performed. Intensities for the higher ions are reported, to our knowledge, for the first time, as they are potentially important for the study of the plasma in astrophysical objects and fusion devices. (1 data file).

Charro, E.; Curiel, Z.; Martin, I.

2002-05-01

334

Package Enhancement Study for the 120-mm M831E2 Cartridge.  

National Technical Information Service (NTIS)

An engineering study to reduce the cost of the existing 120-mm, target practice-tracer (TP-T), M831 tank cartridge, is being conducted by ARDEC, Picatinny Arsenal, NJ. The redesigned cartridge designated M831E2, is packaged in the standard PA116 metal can...

L. Manole R. Dunscomb S. Gilman

1992-01-01

335

Prostaglandin E 2 in temporomandibular joint synovial fluid and its relation to pain and inflammatory disorders  

Microsoft Academic Search

Purpose: The aim of this study was to investigate temporomandibular joint (TMJ) synovial fluid (SF) levels of prostaglandin E2 and its relation to general inflammatory activity and its influence on specific TMJ pain in patients with inflammatory TMJ disorders.Patients and Methods: The study comprised 24 patients (30 joints) with inflammatory TMJ disorders and 4 healthy persons (6 joints). TMJ pain

Per Alstergren; Sigvard Kopp

2000-01-01

336

Investigation of complex ionization amplitudes in cadmium by ([ital e],2[ital e]) spectroscopy  

SciTech Connect

High-resolution ([ital e],2[ital e]) energy spectra are presented which enable the isolation of interference effects between [ital J]=0,1,2 multipoles in electron-impact ionization of cadmium. It is found that both resonant and nonresonant processes are important. Relative magnitudes and phases of ionization amplitudes are obtained which disagree with plane-wave Born approximation calculations.

Martin, N.L.S.; Thompson, D.B.; Bauman, R.P.; Wilson, M. (Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States))

1994-11-01

337

Development and use of a multichannel (e,2e) spectrometer for electron momentum densities of molecules  

Microsoft Academic Search

We have developed an (e,2e) spectrometer with the introduction of modern multiparameter techniques. In particular, the high sensitivity achieved by simultaneous detection in energy and momentum is remarkable, opening up the possibilities of more precise and more advanced studies on the electronic structure of atoms and molecules. To illustrate some of the features, an overview of our recent results is

Y. Udagawa

2004-01-01

338

Exposure to traffic pollutants and effects on 17-?-estradiol (E2) in female workers  

Microsoft Academic Search

Objective: The aim of the study is to evaluate whether the occupational exposure to urban pollutants including endocrine disruptors (EDs) could cause alterations in plasma 17-?-estradiol (E2) levels and related diseases (adverse pregnancy outcome and mental health disorders) in female traffic police compared to a control group. Methods: After excluding the subjects with the principal confounding factors, traffic police and

Gianfranco Tomei; Manuela Ciarrocca; Bruna Rita Fortunato; Assunta Capozzella; Maria Valeria Rosati; Daniela Cerratti; Enrico Tomao; Vincenza Anzelmo; Carlo Monti; Francesco Tomei

2006-01-01

339

(e,2e) collisions in the presence of a laser field  

SciTech Connect

We study the influence of a laser field on the dynamics of fast (e,2e) collisions on atomic hydrogen, in the asymmetric coplanar geometry. We find that the triply differential cross sections are strongly dependent on the ''dressing'' of the atomic target by the laser.

Joachain, C.J.; Francken, P.; Maquet, A.; Martin, P.; Veniard, V.

1988-07-11

340

Phage display identifies an Eastern equine encephalitis virus glycoprotein E2-specific B cell epitope.  

PubMed

The present study identified a linear B-cell epitope in the Eastern equine encephalitis virus (EEEV) E2 glycoprotein by screening a phage-displayed random 12-mer peptide library using an EEEV E2 specific monoclonal antibody (mAb) 7C11 and defined L/F-E/R-Y-T-W-G/R-N-H/W-P as the consensus binding motif. A sequence ((321)EGLEYTWGNHPP(332)) encompassing this consensus motif was found in the EEEV E2 glycoprotein and synthesized for further epitope confirmation. Meanwhile, the corresponding epitope peptides in E2 protein of associated alphaviruses were synthesized for specificity identification. Results showed the mAb 7C11 and murine antisera all reacted strongly against the synthesized polypeptide of EEEV antigen complex, but no reaction with Western equine encephalitis virus (WEEV) and Venezuelan equine encephalitis virus (VEEV) was detected. The knowledge and reagents generated in this study may have potential applications in differential diagnosis and the development of epitope-based marker vaccines against EEEV. PMID:22824180

Zhao, J; Sun, E C; Liu, N H; Yang, T; Xu, Q Y; Qin, Y L; Yang, Y H; Wu, D L

2012-06-29

341

Alterations in Locomotor Activity Induced by Radioprotective Doses of 16,16-Dimethyl Prostaglandin E2,  

National Technical Information Service (NTIS)

16,16-Dimethyl prostaglandin E2 (DiPGE2) is an effective radioprotectant when administered before irradiation. A notable side effect of this compound is sedation. In separate experiments, we investigated the dose-response determinations of the time course...

M. R. Landauer T. L. Walden H. D. Davis J. A. Dominitz

1987-01-01

342

Requirements for dE2F function in proliferating cells and in post-mitotic differentiating cells.  

PubMed Central

The transcription factor E2F is a target of the retinoblastoma tumor suppressor protein (pRB) and may mediate pRB regulation of S phase entry in mammalian cells. The recent identification of mutant alleles of the Drosophila E2F gene (dE2F) has shown that dE2F is required for embryogenesis. dE2F-mutant embryos lack a co-ordinated program of gene expression which accompanies S phase entry and DNA synthesis declines to levels that are barely detectable. We have investigated the role of the dE2F gene at later stages of development. dE2F is expressed in several larval tissues and is required for cell proliferation in the eye imaginal disc. Surprisingly, dE2F expression persists in post-mitotic cells of the eye disc of third-instar larvae. The loss of dE2F function in these cells causes a novel phenotype, characterized by loss of photoreceptors and abnormal rhabdomere cell morphology. These results show that dE2F is required at multiple stages of development and suggest that E2F may have an important function in post-mitotic cells in addition to its role during cell proliferation. Images

Brook, A; Xie, J E; Du, W; Dyson, N

1996-01-01

343

Localization of HPV-18 E2 at Mitochondrial Membranes Induces ROS Release and Modulates Host Cell Metabolism.  

PubMed

Papillomavirus E2 proteins are predominantly retained in the nuclei of infected cells, but oncogenic (high-risk) HPV-18 and 16 E2 can shuttle between the host nucleus and cytoplasm. We show here that cytoplasmic HPV-18 E2 localizes to mitochondrial membranes, and independent mass spectrometry analyses of the E2 interactome revealed association to the inner mitochondrial membrane including components of the respiratory chain. Mitochondrial E2 association modifies the cristae morphology when analyzed by electron microscopy and increases production of mitochondrial ROS. This ROS release does not induce apoptosis, but instead correlates with stabilization of HIF-1? and increased glycolysis. These mitochondrial functions are not shared by the non-oncogenic (low-risk) HPV-6 E2 protein, suggesting that modification of cellular metabolism by high-risk HPV E2 proteins could play a role in carcinogenesis by inducing the Warburg effect. PMID:24086592

Lai, Deborah; Tan, Chye Ling; Gunaratne, Jayantha; Quek, Ling Shih; Nei, Wenlong; Thierry, Françoise; Bellanger, Sophie

2013-09-24

344

Localization of HPV-18 E2 at Mitochondrial Membranes Induces ROS Release and Modulates Host Cell Metabolism  

PubMed Central

Papillomavirus E2 proteins are predominantly retained in the nuclei of infected cells, but oncogenic (high-risk) HPV-18 and 16 E2 can shuttle between the host nucleus and cytoplasm. We show here that cytoplasmic HPV-18 E2 localizes to mitochondrial membranes, and independent mass spectrometry analyses of the E2 interactome revealed association to the inner mitochondrial membrane including components of the respiratory chain. Mitochondrial E2 association modifies the cristae morphology when analyzed by electron microscopy and increases production of mitochondrial ROS. This ROS release does not induce apoptosis, but instead correlates with stabilization of HIF-1? and increased glycolysis. These mitochondrial functions are not shared by the non-oncogenic (low-risk) HPV-6 E2 protein, suggesting that modification of cellular metabolism by high-risk HPV E2 proteins could play a role in carcinogenesis by inducing the Warburg effect.

Gunaratne, Jayantha; Quek, Ling Shih; Nei, Wenlong; Thierry, Francoise; Bellanger, Sophie

2013-01-01

345

Comparative metabolism and structure of BCKD-E2 in primary biliary cirrhosis.  

PubMed

The identification and cloning of the mitochondrial autoantigens in primary biliary cirrhosis (PBC) have provided new clues in disease pathogenesis. The two major autoantigens are the E2 subunits of pyruvate dehydrogenase and branched-chain ketoacid dehydrogenase (BCKD). Interestingly, one of these complexes, BCKD-E2, is already well known to clinical medicine based on its association with genetic mutations in maple syrup urine disease (MSUD). Patients with this disease have an inability to metabolize branched-chain amino acids. In the present study, we have taken advantage of the known sequence of BCKD-E2 from normal humans, and addressed the issue of whether there is an altered autoantigen sequence in hepatocytes of individuals with primary biliary cirrhosis. In particular, we examined both the leader sequence and the B-cell immunodominant epitope, the lipoic acid domain. In addition, because patients with PBC have autoantibodies to the BCKD-E2 complex, we have quantitated plasma levels of alpha-ketoacids potentially affected in maple syrup urine disease. These include pyruvic acid (PY), phenylpyruvic acid (PP), alpha-ketoisocaproic acid (KIC) alpha-ketoisovalerate (KIV) and alpha-keto-beta-methylvaleric acid (KMV). The levels of these alpha-ketoacids were compared in patients with primary sclerosing cholangitis and normal volunteers. The sequence of BCKD-E2 obtained from PBC hepatocytes showed homology with normal BCKD. Further studies of autoantigen structure and sequence are clearly indicated, including those involved in mitochondrial transport and localization. Finally, we noted a statistically significant increase in all plasma alpha-ketoacids except alpha-keto-beta-methylvaleric acid in PBC patients.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8216688

Turchany, J M; Leung, P S; Iwayama, T; Jefferson, D M; Ishida, J; Yamaguchi, M; Munoz, S; Danner, D J; Dickson, E R; Gershwin, M E

1993-08-01

346

pRB-E2F1 complexes are resistant to adenovirus E1A-mediated disruption.  

PubMed

Disruption of pRB-E2F interactions by E1A is a key event in the adenoviral life cycle that drives expression of early viral transcription and induces cell cycle progression. This function of E1A is complicated by E2F1, an E2F family member that controls multiple processes besides proliferation, including apoptosis and DNA repair. Recently, a second interaction site in pRB that only contacts E2F1 has been discovered, allowing pRB to control proliferation separately from other E2F1-dependent activities. Based on this new insight into pRB-E2F1 regulation, we investigated how E1A affects control of E2F1 by pRB. Our data reveal that pRB-E2F1 interactions are resistant to E1A-mediated disruption. Using mutant forms of pRB that selectively force E2F1 to bind through only one of the two binding sites on pRB, we determined that E1A is unable to disrupt E2F1's unique interaction with pRB. Furthermore, analysis of pRB-E2F complexes during adenoviral infection reveals the selective maintenance of pRB-E2F1 interactions despite the presence of E1A. Our experiments also demonstrate that E2F1 functions to maintain cell viability in response to E1A expression. This suggests that adenovirus E1A's seemingly complex mechanism of disrupting pRB-E2F interactions provides selectivity in promoting viral transcription and cell cycle advancement, while maintaining cell viability. PMID:18305049

Seifried, L A; Talluri, S; Cecchini, M; Julian, L M; Mymryk, J S; Dick, F A

2008-02-27

347

Production of classical swine fever virus envelope glycoprotein E2 as recombinant polyhedra in baculovirus-infected silkworm larvae.  

PubMed

Although, classical swine fever virus (CSFV) envelope glycoprotein E2 subunit vaccine has been developed using the baculovirus expression system, the expression of viral antigens in baculovirus-infected insect cells is often ineffective. Therefore, an alternative strategy to the traditional baculovirus expression system is needed that is more productive and effective. Here, we report a novel strategy for the large-scale production of a CSFV E2 in the larvae of a baculovirus-infected silkworm, Bombyx mori. We constructed a recombinant B. mori nucleopolyhedrovirus (BmNPV) that expressed recombinant polyhedra together with the N-terminal 179 amino acids of CSFV E2 (E2?C). BmNPV-E2?C-infected silkworm larvae expressed native polyhedrin and approximately 44-kDa fusion protein that was detected using both anti-polyhedrin and anti-CSFV E2 antibodies. Electron and confocal microscopy both demonstrated that the recombinant polyhedra contained both the fusion protein and native polyhedrin were morphologically normal and contained CSFV E2?C. The CSFV E2?C antigen produced in BmNPV-E2?C-infected silkworm larvae reached 0.68 mg/ml of hemolymph and 0.53 mg/larva at 6-days post-infection. Six-week-old female BALB/c mice that were immunized with the E2?C protein purified from solubilized recombinant polyhedra elicited CSFV E2 antibodies, which indicated that the CSFV E2?C protein from recombinant polyhedra was immunogenic. The virus neutralization test showed that the serum from mice that were treated with E2?C protein from recombinant polyhedra contained significant levels of virus neutralization activity. These results demonstrate that this strategy can be used for the large-scale production of CSFV E2 antigen. PMID:21706129

Lee, Kwang Sik; Sohn, Mi Ri; Kim, Bo Yeon; Choo, Young Moo; Woo, Soo Dong; Yoo, Sung Sik; Je, Yeon Ho; Choi, Jae Young; Roh, Jong Yul; Koo, Hyun Na; Jin, Byung Rae

2012-03-01

348

Effects of nonylphenol on estrogen receptor conformation, transcriptional activity and sexual reversion in rainbow trout (Oncorhynchus mykiss).  

PubMed

Estrogenic potency of 4-n-nonylphenol diethoxylate, 4-n-nonylphenol (NP) and metabolites were tested using two bioassays: rainbow trout hepatocyte culture and recombinant yeast stably expressing rainbow trout estrogen receptor (rtER) and containing estrogen-dependent reporter genes. Since NP was the only compound active in both systems, its interaction with rtER was studied in more detail. Qualitative and quantitative differences were observed in the presence of 17beta-estradiol (E2) or NP when estrogen-dependent promoters containing one to three estrogen-responsive elements were used in yeast. Moreover, limited proteolysis of rtER after E2 or NP binding presented different patterns after SDS-PAGE analysis suggesting that NP induces a differential conformation of rtER compare to E2. This finding may have important implications with respect to the biological activity of NP. Thus, the effects of NP on the activation of an E2-dependent gene and on sexual differentiation were assessed on all-male trout embryos exposed to NP for 1 h per day for 10 days. Although in situ hybridization demonstrated that E2, and to a lesser extend NP, were able to increase rtER mRNA level in the liver of embryos, no indication of total or partial sexual reversion was observed (even in E2 treated fishes) when the gonads were examined 8 months after hatching. PMID:11408078

Madigou, T; Le Goff, P; Salbert, G; Cravedi, J P; Segner, H; Pakdel, F; Valotaire, Y

2001-08-01

349

Nongenomic inhibition of coronary constriction by 17ß-estradiol, 2-hydroxyestradiol, and 2-methoxyestradiol.  

PubMed

The cardioprotective effects of 17beta-estradiol (E2) in women are hypothesized to be partially mediated by the E2 metabolites 2-hydroxyestradiol (2-HOE) and 2-methoxyestradiol (2-MeOH). Therefore, the purpose of our study was to determine the acute effects of E2, 2-HOE, and 2-MeOH on inhibition of coronary arterial constriction. Right coronary arteries obtained from breeding sows were cut into 4 mm rings and suspended in organ baths. Incubation of the rings with E2, 2-HOE, and 2-MeOH (10 micromol/L) for 60 min attenuated a subsequent KCl-induced contraction by approximately 50%. The protein synthesis inhibitor cycloheximide and the estrogen receptor antagonists ICI 182780 and tamoxifen did not affect the attenuation. Moreover, E2, 2-HOE, and 2-MeOH antagonized the contraction induced by the vasospasm agonist endothelin-1 (0.1 micromol/L) by approximately 36%. When the L-type Ca2+ channel blocker nifedipine was added at the conclusion of the experiment, no additional contractile attenuation was present. Our results suggest that E2, 2-HOE, and 2-MeOH demonstrate a similar nongenomic inhibition of agonist-induced extracellular Ca2+-dependent contractions. PMID:20237589

Hill, Brent J F; Gebre, Senetibeb; Schlicker, Bonnie; Jordan, Renée; Necessary, Sean

2010-02-01

350

Development of a mouse model of mammary gland versus uterus tissue selectivity using estrogen- and progesterone-regulated gene markers.  

PubMed

We have identified mRNA markers of estradiol and progesterone action in the mouse mammary gland and uterus to establish an in vivo model for the evaluation of novel and potentially tissue selective estrogens and progestins. Gene chip analysis of mRNA from ovariectomized (OVX) mice treated with vehicle (V), 17beta-estradiol (E2), progesterone (P) or E2+P for 7 days identified defensinbeta1 (Defbeta1) and indoleamine-pyrrole 2,3 dioxygenase (INDO) as markers of E2 and P action in the mammary gland, and serine protease inhibitor, Kazal type 3 (Spink3) and G protein-coupled receptor 105 (GPR105) as markers in the uterus. Defbeta1 and Spink3 are both upregulated by E2+P, whereas INDO and GPR105 have a complementary profile of upregulation by E2 alone and suppression of the E2 effect by P. Quantitative RT-PCR analysis of mammary gland markers was concordant with histological changes. Using this model, medroxyprogesterone acetate (MPA) and tanaproget (TNPR), a novel nonsteroidal progesterone receptor agonist, were evaluated and found to have no marked tissue selectivity relative to progesterone. In addition, the ERalpha selective ligand propyl pyrazole triol (PPT) and the ERbeta selective ligands ERB-041 and WAY-202196 were evaluated on the mammary gland endpoints of histology and Defbeta1 mRNA expression, and showed that ERalpha stimulation is necessary and sufficient for eliciting estradiol-mediated changes in the mammary gland. PMID:16920353

Crabtree, Judy S; Zhang, Xiaochun; Peano, Bryan J; Zhang, Zhiming; Winneker, Richard C; Harris, Heather A

2006-08-22

351

The development of diabetes in E2f1/E2f2 mutant mice reveals important roles for bone marrow-derived cells in preventing islet cell loss  

PubMed Central

Our studies of mice deficient for the E2F1 and E2F2 transcription factors have revealed essential roles for these proteins in the cell cycle control of pancreatic exocrine cells and the regulation of pancreatic beta cell maintenance. Pancreatic exocrine cells in E2f1/E2f2 mutant mice become increasingly polyploid with age, coinciding with severe exocrine atrophy. Furthermore, mice deficient for both E2F1 and E2F2 develop nonautoimmune, insulin-dependent diabetes with high penetrance. Surprisingly, transplantation of wild-type bone marrow can prevent or rescue diabetes in E2f1-/-E2f2-/- mice. We hypothesize that exocrine degeneration results in a destructive environment for beta cells, which can be alleviated by restoration of the hematopoietic system that is also defective in E2f1-/-E2f2-/- mice. The demonstration that beta cell maintenance under conditions of stress is influenced by bone marrow-derived cells may provide important insight into the design of therapies to boost islet mass and function in diabetic patients.

Li, Feng X.; Zhu, Jing W.; Tessem, Jeffery S.; Beilke, Joshua; Varella-Garcia, Marileila; Jensen, Jan; Hogan, Christopher J.; DeGregori, James

2003-01-01

352

Changes in Prostaglandin E2 Levels in Seminal Plasma during Ejaculation and the Effect of Exogenous Prostaglandin E2 on Semen Volume in the Dog.  

PubMed

In healthy male dogs, peripheral plasma testosterone (T), prostaglandin E2 (PGE2), and seminal plasma PGE2 levels were measured before, during, and after ejaculation and semen quality was examined after oral administration of PGE2. Plasma T and PGE2 levels did not change during these periods, but seminal plasma PGE2 level in the first and second fraction was significantly higher than that at 0-5 and 5-10 min after the start of ejaculation of the third fraction. Semen volume but not quality increased after PGE2 administration. In conclusion, large amounts of PGE2 are released from the prostate gland during the early part of ejaculation and that PGE2 plays an essential role in secretion of seminal plasma. PMID:23629017

Kobayashi, Masanori; Hori, Tatsuya; Kawakami, Eiichi

2013-04-30

353

AVPV neurons containing estrogen receptor-beta in adult male rats are influenced by soy isoflavones  

Microsoft Academic Search

BACKGROUND: Isoflavones, the most abundant phytoestrogens in soy foods, are structurally similar to 17beta-estradiol. It is known that 17beta-estradiol induces apoptosis in anteroventral periventricular nucleus (AVPV) in rat brain. Also, there is evidence that consumption of soy isoflavones reduces the volume of AVPV in male rats. Therefore, in this study, we examined the influence of dietary soy isoflavones on apoptosis

Lihong Bu; Edwin D Lephart

2007-01-01

354

E2F7 represses a network of oscillating cell cycle genes to control S-phase progression  

PubMed Central

E2F transcription factors are known to be important for timely activation of G1/S and G2/M genes required for cell cycle progression, but transcriptional mechanisms for deactivation of cell cycle-regulated genes are unknown. Here, we show that E2F7 is highly expressed during mid to late S-phase, occupies promoters of G1/S-regulated genes and represses their transcription. ChIP-seq analysis revealed that E2F7 binds preferentially to genomic sites containing the TTCCCGCC motif, which closely resembles the E2F consensus site. We identified 89 target genes that carry E2F7 binding sites close to the transcriptional start site and that are directly repressed by short-term induction of E2F7. Most of these target genes are known to be activated by E2Fs and are involved in DNA replication, metabolism and DNA repair. Importantly, induction of E2F7 during G0-G1/S resulted in S-phase arrest and DNA damage, whereas expression of E2F7 during G2/M failed to disturb cell cycle progression. These findings provide strong evidence that E2F7 directly controls the downswing of oscillating G1/S genes during S-phase progression.

Westendorp, Bart; Mokry, Michal; Groot Koerkamp, Marian J.A.; Holstege, Frank C.P.; Cuppen, Edwin; de Bruin, Alain

2012-01-01

355

Characterization of an E2F1-specific binding domain in pRB and its implications for apoptotic regulation.  

PubMed

The retinoblastoma protein (pRB) has the dual capability to negatively regulate both E2F-induced cell cycle entry and E2F1-induced apoptosis. In this report, we characterize a unique pRB-E2F1 interaction. Using mutagenesis to disrupt E2F1 binding, we find that the ability of pRB to regulate E2F1-induced apoptosis is diminished when this interaction is lost. Strikingly, this mutant form of pRB retains the ability to control E2F responsive cell cycle genes and blocks cell proliferation. These functional properties are the reciprocal of a previously described E2F binding mutant of pRB that interacts with E2F1, but lacks the ability to interact with other E2Fs. Our work shows that these distinct interactions allow pRB to separately regulate E2F-induced cell proliferation and apoptosis. This suggests a novel form of regulation whereby separate types of binding contacts between the same types of molecules can confer distinct functional outcomes. PMID:17891180

Julian, L M; Palander, O; Seifried, L A; Foster, J E G; Dick, F A

2007-09-24

356

Deregulated expression of E2F1 induces hyperplasia and cooperates with ras in skin tumor development.  

PubMed

In cell culture studies, overexpression of the E2F1 transcription factor has been shown to stimulate proliferation, induce apoptosis, and cooperate with an activated ras gene to oncogenically transform primary rodent cells. To study the effect of increased E2F1 activity on epithelial growth and tumorigenesis in vivo, transgenic mice expressing E2F1 under the control of a keratin 5 (K5) promoter were generated. Expression of E2F1 in the epidermis results in hyperplasia but does not inhibit terminal differentiation. In a transgenic line expressing high levels of E2F1, mice have decreased hair growth likely as a result of aberrant apoptosis in developing hair follicles. Coexpression of a cyclin D1 transgene with E2F1 augments epidermal hyperplasia and further disrupts hair follicle development suggesting that hypophosphorylated Rb antagonizes the proliferative and apoptotic-promoting activities of E2F1. Finally, the E2F1 transgene is found to cooperate with a v-Ha-ras transgene to induce skin tumors in double transgenic animals. These findings confirm that many of the activities ascribed to E2F1 through in vitro studies can be reproduced in vivo and demonstrate for the first time that deregulated E2F activity can contribute to tumor development. PMID:9546428

Pierce, A M; Fisher, S M; Conti, C J; Johnson, D G

1998-03-12

357

Interaction of the Most Membranotropic Region of the HCV E2 Envelope Glycoprotein with Membranes. Biophysical Characterization  

PubMed Central

The previously identified membrane-active regions of the hepatitis C virus (HCV) E1 and E2 envelope glycoproteins led us to identify different segments that might be implicated in viral membrane fusion, membrane interaction, and/or protein-protein binding. HCV E2 glycoprotein contains one of the most membranotropic segments, segment 603–634, which has been implicated in CD81 binding, E1/E2 and E2/E2 dimerization, and membrane interaction. Through a series of complementary experiments, we have carried out a study of the binding and interaction with the lipid bilayer of a peptide corresponding to segment 603–634, peptide E2FP, as well as the structural changes induced by membrane binding that take place in both the peptide and the phospholipid molecules. Here, we demonstrate that peptide E2FP binds to and interacts with phospholipid model membranes, modulates the polymorphic phase behavior of membrane phospholipids, is localized in a shallow position in the membrane, and is probably oligomerized in the presence of membranes. These data support the role of E2FP in HCV-mediated membrane fusion, and sustain the notion that this segment of the E2 envelope glycoprotein, together with other segments of E2 and E1 glycoproteins, provides the driving force for the merging of the viral and target cell membranes.

Perez-Berna, Ana J.; Guillen, Jaime; Moreno, Miguel R.; Gomez-Sanchez, Ana I.; Pabst, George; Laggner, Peter; Villalain, Jose

2008-01-01

358

Deregulated expression of E2F1 promotes proteolytic degradation of tumor suppressor p73 and inhibits its transcriptional activity.  

PubMed

The expression of tumor suppressor p73 is regulated at mRNA and protein levels. It has been shown that E2F1 acts as a transcriptional activator for p73. In this study, we have found that deregulated expression of E2F1 increases the mRNA level of p73, however, E2F1 promotes the degradation of p73. Immunoprecipitation experiments demonstrated that E2F1 forms a complex with p73 and inhibits the transcriptional activity of p73. Enforced expression of E2F1 induces degradation of p73 in a proteasome-independent manner. Additionally, the deletion analysis showed that E2F1(1-117) has an undetectable effect on p73, whereas E2F1(1-285) and E2F1(1-414) have an ability to promote degradation of p73 and inhibition of p73 transcriptional activity, suggesting that the region of E2F1 between amino acid residues 118 and 285 has a critical role in the regulation of p73. Taken together, our present study indicates that E2F1 has a dual role in the regulation of p73. PMID:19576172

Ozaki, Toshinori; Okoshi, Rintaro; Ono, Sayaka; Kubo, Natsumi; Nakagawara, Akira

2009-07-01

359

How Does (E)-2-(Acetamidomethylene)succinate Bind to Its Hydrolase? From the Binding Process to the Final Result  

PubMed Central

The binding of (E)-2-(acetamidomethylene)succinate (E-2AMS) to E-2AMS hydrolase is crucial for biological function of the enzyme and the last step reaction of vitamin B6 biological degradation. In the present study, several molecular simulation methods, including molecular docking, conventional molecular dynamics (MD), steered MD (SMD), and free energy calculation methods, were properly integrated to investigate the detailed binding process of E-2AMS to its hydrolase and to assign the optimal enzyme-substrate complex conformation. It was demonstrated that the substrate binding conformation with trans-form amide bond is energetically preferred conformation, in which E-2AMS's pose not only ensures hydrogen bond formation of its amide oxygen atom with the vicinal oxyanion hole but also provides probability of the hydrophobic interaction between its methyl moiety and the related enzyme's hydrophobic cavity. Several key residues, Arg146, Arg167, Tyr168, Arg179, and Tyr259, orientate the E-2AMS's pose and stabilize its conformation in the active site via the hydrogen bond interaction with E-2AMS. Sequentially, the binding process of E-2AMS to E-2AMS hydrolase was studied by SMD simulation, which shows the surprising conformational reversal of E-2AMS. Several important intermediate structures and some significant residues were identified in the simulation. It is stressed that Arg146 and Arg167 are two pivotal residues responsible for the conformational reversal of E-2AMS in the binding or unbinding. Our research has shed light onto the full binding process of the substrate to E-2AMS hydrolase, which could provide more penetrating insight into the interaction of E-2AMS with the enzyme and would help in the further exploration on the catalysis mechanism.

Zhang, Ji-Long; Zheng, Qing-Chuan; Li, Zheng-Qiang; Zhang, Hong-Xing

2013-01-01

360

Enhancement of Immunoglobulin G2a and Cytotoxic T-Lymphocyte Responses by a Booster Immunization with Recombinant Hepatitis C Virus E2 Protein in E2 DNA-Primed Mice  

Microsoft Academic Search

The induction of strong cytotoxic T-lymphocyte (CTL) and humoral responses appear to be essential for the elimination of persistently infecting viruses, such as hepatitis C virus (HCV). Here, we tested several vaccine regimens and demonstrate that a combined vaccine regimen, consisting of HCV E2 DNA priming and boosting with recombinant E2 protein, induces the strongest immune responses to HCV E2

MAN KI SONG; SEUNG WOO LEE; YOU SUK SUH; KI JEONG LEE; YOUNG CHUL SUNG

2000-01-01

361

In-band M1 and E2 transition rates and collective structures in 128Ba  

NASA Astrophysics Data System (ADS)

Subpicosecond mean lifetimes of eight excited states in 128Ba populated via the 96Zr(36S,4n) reaction were measured by the Doppler-shift attenuation (DSA) technique using a line-shape analysis. The differential decay-curve method (DDCM) was applied for the lifetime determination. The B(E2) values in the yrast band indicate that the first band-crossing is with a proton S-band. The configuration ?h11/2d5/2 of the negative-parity semi-decoupled bands is confirmed by the measured B(E2,I-->I-2) and B(M1,I-->I-1) transition strengths. The higher-lying ``dipole'' band in 128Ba can be described as a high-K four-quasiparticle band built on the prolate configuration (?h11/2d5/2)?(?h11/2g7/2).

Petkov, P.; Gableske, J.; Vogel, O.; Dewald, A.; von Brentano, P.; Krücken, R.; Peusquens, R.; Nicolay, N.; Gizon, A.; Gizon, J.; Bazzacco, D.; Rossi-Alvarez, C.; Lunardi, S.; Pavan, P.; Napoli, D. R.; Andrejtscheff, W.; Jolos, R. V.

1998-09-01

362

Vector infection determinants of Venezuelan equine encephalitis virus reside within the E2 envelope glycoprotein.  

PubMed

Epizootic subtype IAB and IC Venezuelan equine encephalitis viruses (VEEV) readily infect the epizootic mosquito vector Aedes taeniorhynchus. The inability of enzootic subtype IE viruses to infect this mosquito species provides a model system for the identification of natural viral determinants of vector infectivity. To map mosquito infection determinants, reciprocal chimeric viruses generated from epizootic subtype IAB and enzootic IE VEEV were tested for mosquito infectivity. Chimeras containing the IAB epizootic structural gene region and, more specifically, the IAB PE2 envelope glycoprotein E2 precursor gene demonstrated an efficient infection phenotype. Introduction of the PE2 gene from an enzootic subtype ID virus into an epizootic IAB or IC genetic backbone resulted in lower infection rates than those of the epizootic parent. The finding that the E2 envelope glycoprotein, the site of epitopes that define the enzootic and epizootic subtypes, also encodes mosquito infection determinants suggests that selection for efficient infection of epizootic mosquito vectors may mediate VEE emergence. PMID:12021373

Brault, Aaron C; Powers, Ann M; Weaver, Scott C

2002-06-01

363

E2F1 and p53 Transcription Factors as Accessory Factors for Nucleotide Excision Repair  

PubMed Central

Many of the biochemical details of nucleotide excision repair (NER) have been established using purified proteins and DNA substrates. In cells however, DNA is tightly packaged around histones and other chromatin-associated proteins, which can be an obstacle to efficient repair. Several cooperating mechanisms enhance the efficiency of NER by altering chromatin structure. Interestingly, many of the players involved in modifying chromatin at sites of DNA damage were originally identified as regulators of transcription. These include ATP-dependent chromatin remodelers, histone modifying enzymes and several transcription factors. The p53 and E2F1 transcription factors are well known for their abilities to regulate gene expression in response to DNA damage. This review will highlight the underappreciated, transcription-independent functions of p53 and E2F1 in modifying chromatin structure in response to DNA damage to promote global NER.

Velez-Cruz, Renier; Johnson, David G.

2012-01-01

364

Vector Infection Determinants of Venezuelan Equine Encephalitis Virus Reside within the E2 Envelope Glycoprotein  

PubMed Central

Epizootic subtype IAB and IC Venezuelan equine encephalitis viruses (VEEV) readily infect the epizootic mosquito vector Aedes taeniorhynchus. The inability of enzootic subtype IE viruses to infect this mosquito species provides a model system for the identification of natural viral determinants of vector infectivity. To map mosquito infection determinants, reciprocal chimeric viruses generated from epizootic subtype IAB and enzootic IE VEEV were tested for mosquito infectivity. Chimeras containing the IAB epizootic structural gene region and, more specifically, the IAB PE2 envelope glycoprotein E2 precursor gene demonstrated an efficient infection phenotype. Introduction of the PE2 gene from an enzootic subtype ID virus into an epizootic IAB or IC genetic backbone resulted in lower infection rates than those of the epizootic parent. The finding that the E2 envelope glycoprotein, the site of epitopes that define the enzootic and epizootic subtypes, also encodes mosquito infection determinants suggests that selection for efficient infection of epizootic mosquito vectors may mediate VEE emergence.

Brault, Aaron C.; Powers, Ann M.; Weaver, Scott C.

2002-01-01

365

Fourier transform emission spectroscopy of the E2?-X2?+ transition of BaH  

NASA Astrophysics Data System (ADS)

The emission spectra of E2?-X2?+ transition of BaH have been reinvestigated at high resolution using the Fourier transform spectrometer associated with the McMath-Pierce Solar Telescope of the National Solar Observatory. Bands observed in the ?v = 0 sequence have been measured and a rotational analysis of the 0-0, 1-1 and 2-2 bands has been obtained. The present measurements have been combined with the previous infrared vibration-rotation measurements of the ground state to provide improved spectroscopic constants for the E2? state. The principal spectroscopic constants of this state obtained from this analysis are: ?e = 1221.912(12) cm-1, ?exe = 15.6682(60) cm-1, Be = 3.520609(41) cm-1 and re = 2.187651(13) Å.

Ram, R. S.; Bernath, P. F.

2013-01-01

366

Calibration and Characterization of the XRS Spectrometer on board ASTRO-E2  

Microsoft Academic Search

We will present an overview of the ground calibration campaign for the high-resolution X-ray Spectrometer (XRS), which will be launched in 2005 as part of the ASTRO-E2 mission. The XRS consists of a microcalorimeter array with a nearly constant energy resolution of 6 eV across the operating band of 0.4 - 10 keV. The effective area of the spectrometer has

J. Cottam; K. R. Boyce; G. V. Brown; E. Figueroa-Feliciano; T. Furusho; R. L. Kelley; F. S. Porter; C. K. Stahle; W. A. Tillotson

2003-01-01

367

Performance Verification of the Astro-E2 X-ray spectrometer in the flight configuration  

Microsoft Academic Search

The X-ray Spectrometer (XRS) is a high resolution, non-dispersive cryogenic detector on board the X-ray satellite, Astro-E2 (Suzaku), which was successfully launched on July 10, 2005. The XRS achieves an energy resolution of 6 eV at 6 keV (FWHM) and covers a broad energy range of â 0.07-10 keV. The XRS will enable powerful plasma diagnostics of a variety of

N Ota; K R Boyce; G V Brown; J Cottam; R Fujimoto; T Furusho; Y Ishisaki; R L Kelley; C A Kilbourne; D McCammon; K Mitsuda; U Morita; F S Porter; Y Takei; M Yamamoto

2005-01-01

368

The In-Flight Calibration Program for the XRS on Astro-E2  

Microsoft Academic Search

The X-ray Spectrometer (XRS) will be launched in February 2005 as part of the Astro-E2 mission. It will provide unprecedented throughput and resolving powers particularly at high energies. In this presentation we will describe the in-flight calibration program. The energy scale of the XRS is a complex non-linear function of the noise and power conditions on the array. It will

J. Cottam; C. A. Kilbourne

2004-01-01

369

Characterization of the Astro-E2 X-ray spectrometer  

Microsoft Academic Search

We present the results of extensive characterization tests of the X-ray Spectrometer (XRS), which will be launched in 2005 as part of the Astro-E2 mission. The XRS will utilize a newly developed 2-D microcalorimeter array of 32 pixels that will provide a resolution of ?6eV over the energy range 0.3–10keV. The detector is characterized by the energy scale and energy

J. Cottam; K. R. Boyce; G. V. Brown; E. Figueroa-Feliciano; R. L. Kelley; V. Ponce; F. S. Porter; C. K. Stahle; W. A. Tillotson

2004-01-01

370

The next-generation microcalorimeter array of XRS on Astro-E2  

Microsoft Academic Search

The square-format 32-pixel microcalorimeter array at the focal plane of the high-resolution X-ray spectrometer on the Astro-E2 X-ray Observatory is the first of a new generation of silicon-based microcalorimeters. This array has numerous advantages over its predecessor, the bilinear array that was launched on Astro-E. Foremost among its benefits are: (1) the energy resolution is improved by a factor of

C. K. Stahle; C. A. Allen; K. R. Boyce; R. P. Brekosky; G. V. Brown; J. Cottam; E. Figueroa-Feliciano; M. Galeazzi; J. D. Gygax; M. B. Jacobson; R. L. Kelley; D. Liu; D. McCammon; R. A. McClanahan; S. H. Moseley; F. S. Porter; L. E. Rocks; A. E. Szymkowiak; J. E. Vaillancourt

2004-01-01

371

Subdivision of the PestivirusGenus Based on Envelope Glycoprotein E2  

Microsoft Academic Search

Conventionally, the genusPestivirusof the familyFlaviviridaehas been divided into bovine viral diarrhea virus (BVDV), classical swine fever virus (CSFV), and border disease virus (BDV). To date, BDV and BVDV have been isolated from different species, whereas CSFV seems to be restricted to swine. Pestiviruses are structurally and antigenically closely related. Envelope glycoprotein E2 is the most immunogenic and most variable protein

P. A. van Rijn; H. G. P. van Gennip; C. H. Leendertse; C. J. M. Bruschke; D. J. Paton; R. J. M. Moormann; J. T. van Oirschot

1997-01-01

372

Consistent interpretation of B(E2) values and g factors in deformed nuclei  

SciTech Connect

A simple phenomenological model is discussed that simultaneously accounts for the saturation of B(E2; 0{sub 1}{sup +}{yields} 2{sub 1}{sup +}) values and the newly recognized near constancy of g(2{sub 1}{sup +}) factor values in deformed nuclei. The model invokes reduced effective contributions to these observables from the valence neutrons and protons. Empirical evidence supporting this ansatz comes from recently extracted proton-neutron interaction strengths.

Zhang Jingye [Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States); Casten, R.F.; McCutchan, E.A. [Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Wolf, A.; Berant, Z. [Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Nuclear Research Center Negev, Beer-Sheva (Israel); Cakirli, R.B. [Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, University of Istanbul, Istanbul (Turkey); Zamfir, N. V. [National Institute of Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

2006-03-15

373

Prostaglandin-E2 Is a Potent Inhibitor of Human Interleukin 12 Production  

Microsoft Academic Search

Summary During human immunodeficiency virus infection and allergic diseases, characterized by a dominant T helper (Th) 2 response, overproduction of prostaglandin E2 (PGE2) is observed. In this paper we studied the effect of PGE2 on interleukin (IL)-12 synthesis, because this cytokine has been described to be essential in induction of Thl responses. IL-12 synthesis was induced in monocytes that were

Leonie C. M. Boeije; Ruud J. T. Smeenk; John Wijdenes; Lucien A. Aarden; Boulevard A-Fleming

1995-01-01

374

Ellipsoidal corrections to order e 2 of geopotential coefficients and Stokes’ formula  

Microsoft Academic Search

Assuming that the gravity anomaly and disturbing potential are given on a reference ellipsoid, the result of Sjöberg (1988, Bull Geod 62:93–101) is applied to derive the potential coefficients on the bounding sphere of the ellipsoid to order e 2 (i.e. the square of the eccentricity of the ellipsoid). By adding the potential coefficients and continuing the potential downward to

L. E. Sjöberg

2003-01-01

375

Longitudinal evaluation of prostaglandin E 2 (PGE 2) and periodontal status in HIV + patients  

Microsoft Academic Search

The study aim was to determine whether prostaglandin E2 (PGE2) in gingival crevicular fluid (GCF) could serve as a risk factor for periodontitis in human immunodeficiency virus-positive (HIV+) patients.Clinical measurements, including gingival index (GI), plaque index, bleeding index, probing depth (PD), attachment loss (AL) and GCF samples were taken from two healthy sites (including sites with gingival recession, GI=0; PD?3mm;

Tamer Alpagot; John Remien; Mouchumi Bhattacharyya; Krystyna Konopka; William Lundergan; Nejat D?zg?ne?

2007-01-01

376

Prostaglandin E2 Regulates Interleukin1?-induced Matrix Metalloproteinase-3 Production in Human Gingival Fibroblasts  

Microsoft Academic Search

Prostaglandin E2 (PGE2) exerts its biological actions via EP receptors (EP1, EP2, EP3, and EP4). In the present study, we investigated whether PGE2 regulated interleukin (IL)-1?-induced matrix metalloproteinase (MMP)-3 production in human gingival fibroblasts (HGF) derived from periodontally healthy subjects and diseased patients. In HGF from healthy gingiva, PGE2 down-regulated IL-1?-induced MMP-3 production, whereas in HGF from periodontitis patients, PGE2

S. M. P. M. Ruwanpura; K. Noguchi; I. Ishikawa

2004-01-01

377

Cyclosporin A inhibits prostaglandin E2 formation by rat mesangial cells in culture  

Microsoft Academic Search

Cyclosporin A inhibits prostaglandin E2 formation by rat mesangial cells in culture. A reversible reduction in glomerular filtration rate (GFR) is a frequent side effect in patients treated with the immunosuppressant cyclosporin A (CsA). The pathophysiology of acute CsA nephrotoxicity, however, is unclear. Since eicosanoids are local mediators of glomerular hemodynamics, they might be involved in CsA induced changes in

Rolf A K Stahl; Stephen Adler; Patricia J Baker; Richard J Johnson; Yi-Pu Che