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PubMed1999

Variation at the von Willebrand factor (vWF) gene locus is associated with plasma vWF:Ag levels: identification of three novel single nucleotide polymorphisms in the vWF gene promoter.

Both genetic and environmental factors contribute to the normal population variability of plasma von Willebrand Factor (vWF) levels, however, regulatory mechanisms at the vWF gene locus itself have not yet been identified. We have investigated the association between polymorphic variation in the 5'-regulatory region of the vWF gene and levels of plasma vWF:Ag in a study of 261 group O blood donors. Three novel single nucleotide polymorphisms (SNPs) were identified in the vWF promoter: C/T at -1234, A/G at -1185, and G/A at -1051. These SNPs had identical allele frequencies of 0.36 for the -1234C, -1185A, and -1051G alleles and 0.64 for the -1234T, -1185G, and -1051A alleles and were in strong linkage disequilibrium. In fact, these polymorphisms segregated as two distinct haplotypes: -1234C/-1185A/-1051G (haplotype 1) and -1234T/-1185G/-1051A (haplotype 2) with 12.6% of subjects homozygous for haplotype 1, 40. 6% homozygous for haplotype 2, and 42.5% of subjects heterozygous for both haplotypes. Only 4.3% of individuals had other genotypes. A significant association between promoter genotype and level of plasma vWF:Ag was established (analysis of covariance [ANCOVA], P =. 008; Kruskal-Wallis test, P =.006); individuals with the CC/AA/GG genotype had the highest mean vWF:Ag levels (0.962 U/mL), intermediate values of vWF:Ag (0.867 U/mL) were observed for heterozygotes (CT/AG/GA), and those with the TT/GG/AA genotype had the lowest mean plasma vWF:Ag levels (0.776 U/mL). Interestingly, when the sample was subgrouped according to age, the significant association between promoter genotype and plasma vWF:Ag level was accentuated in subjects > 40 years of age (analysis of variance [ANOVA], P =.003; Kruskal-Wallis test, P =.001), but was not maintained for subjects </= 40 years of age (ANOVA, P >.4; Kruskal-Wallis test, P >.4). In the former subgroup, mean levels of plasma vWF:Ag for subjects with the CC/AA/GG, CT/AG/GA, and TT/GG/AA genotypes were 1.075, 0.954, and 0.794 U/mL, respectively. By searching a transcription factor binding site profile database, these polymorphic sequences were predicted to interact with several transcription factors expressed in endothelial cells, including Sp1, GATA-2, c-Ets, and NFkappaB. Furthermore, the binding sites at the -1234 and -1051 SNPs appeared to indicate allelic preferences for some of these proteins. Electrophoretic mobility shift assays (EMSAs) performed with recombinant human NFkappaB p50 showed preferential binding of the -1234T allele (confirmed by supershift EMSAs), and EMSAs using bovine aortic endothelial cell (BAEC) nuclear extracts produced specific binding of a nuclear protein to the -1051A allele, but not the -1051G allele. These findings suggest that circulating levels of vWF:Ag may be determined, at least in part, by polymorphic variation in the promoter region of the vWF gene, and that this association may be mediated by differential binding of nuclear proteins involved in the regulation of vWF gene expression.

Adult↗

PubMed2004

[Effect of nuclear factor-kappaB on signal transduction of passively sensitized human airway smooth muscle cells proliferation].

OBJECTIVE: To investigate whether nuclear factor-kappaB (NF-kappaB) contributes to passively sensitized human airway smooth muscle cell (HASMCs) proliferation, and whether it is the downstream factor of activated protein kinase C (PKC). METHODS: HASMCs in culture were passively sensitized with 10% serum from asthmatic patients, with non-asthmatic human serum treated HASMCs as the control. NF-kappaB specific inhibitor pyrrolidine dithiocarbamate (PDTC) and PKC agonist phorbol 12-myristate 13-acetate (PMA) were used to intervene HASMCs exposed to asthmatic serum and non-asthmatic control serum. The proliferation of HASMCs was examined by cell cycle analysis, MTT colorimetric assay and proliferating cell nuclear antigen (PCNA) immunofluorescence staining respectively. NF-kappaB activity was detected by NF-kappaBp65 immunofluorescence staining and electrophoretic mobility shift assay (EMSA) respectively. RESULTS: (1) The percentage of S phase, A value, the positive expression rate of PCNA, the positive expression rate of NF-kappaBp65 and EMSA value in HASMCs passively sensitized with asthmatic serum were (21.78 +/- 2.79)%, 0.466 +/- 0.058, (67.5 +/- 8.5)%, (12.6 +/- 2.2)% and 32 781 +/- 9499 respectively. They were significantly increased compared with those of the control serum group (P < 0.05). After previously treated with PDTC, the above figures were decreased to (16.37 +/- 3.05)%, 0.389 +/- 0.035, (53.4 +/- 5.1)%, (4.9 +/- 1.3)% and 3934 +/- 937 respectively (P < 0.05). (2) After HASMCs were treated with both PMA and asthmatic serum, the percentage of S phase, A value, the positive expression rate of PCNA, the positive expression rate of NF-kappaBp65 and EMSA value were (25.52 +/- 3.38)%, 0.572 +/- 0.054, (81.2 +/- 10.2)%, (26.5 +/- 5.0)% and 71 654 +/- 12 293 respectively. After previously treated with PDTC, the above figures were (16.42 +/- 2.72)%, 0.386 +/- 0.031, (54.2 +/- 5.3)%, (5.9 +/- 1.4)% and 4808 +/- 1084 respectively. The difference was significant (P < 0.05). CONCLUSIONS: NF-kappaB may contribute to the proliferation of HASMCs passively sensitized with human asthmatic serum, which involves the PKC/NF-kappaB signal pathway.

Adult↗

PubMed2005

[Binding and inhibition of adeno-associated virus Rep78 protein with hepatitis B virus C promoter].

OBJECTIVES: Adeno-associated virus (AAV) Rep78 is known for its inhibitory effects on replication of several viruses and oncogenes transformations. The study was to investigate the effect of Rep78 on hepatitis B virus C (HBV-C) gene and the mechanism of it. METHODS: HBV-C promoter and HBV-C gene with its promoter were amplified by PCR and labeled with 32P-ATP. Electrophoretic mobility shift assay (EMSA) and in vitro transcription were utilized to detect the binding of MBP-Rep78 with HBV-C promoter and the transcription of HBV-C gene. RESULTS: EMSA showed that by increasing the amount of Rep78 protein from 0.1 microg to 1.0 microg, the binding bands got stronger in a dose-dependent manner. In addition, Rep78 antibody was used to certify the specificity of this binding. The compound of Rep78, Rep78 antibody and HBV-C promoter were seen as super shift bands in EMSA. Meanwhile, HBV-C gene transcription was significantly inhibited by in vitro transcription which meant that Rep78 could not only bind with HBV-C promoter, but also could inhibit the transcription of HBV-C gene. CONCLUSION: AAV Rep78 could inhibit the transcription of HBV-C gene through its binding with HBV-C promoter.

DNA-Binding Proteins↗

PubMed2005

[Preliminary analysis of the 5'-flanking region of rat gamma-glutamylcysteine synthetase catalytic subunit gene].

OBJECTIVE: To analyze the characteristic of regulatory elements and corresponding transcriptional factors in the 5'-flanking region of rat gamma-glutamylcysteine synthetase (gamma-GCS) catalytic subunit (GCLC) gene. METHODS: A 1 760 bp 5'-flanking region of the rat GCLC was cloned and constructed into pGL-3 enhancer vector which includes luciferase reporter gene. Exonuclease III was used to cut the 5'-flanking region of rat GCLC gene unidirectionally into deletion mutants of different length, GCLC-Luc and its deletion mutants were used to transfect rat alveolar epithelium cells CCL-149, then the regulatory region of the gene was determined by luciferase activity assay of the transfected cells. Analysis of the transcription-factor-binding site was done using Transcription Factor Search software to indicate possible transcriptional factors. Electrophoresis mobility shift assay (EMSA) was used to determine the cis-acting elements and transcriptional factors in these regulatory regions. RESULTS: The experiment cloned the upstream regulatory sequence of rat GCLC gene and its reporter vector GCLC-Luc, as well as 11 deletion mutants of GCLC-Luc. Luciferase activity assay of the cells transfected by GCLC-Luc (-1 758/+2-Luc), mutant 1 (-1 231/+2-Luc), mutant 2 (-1 108/+2-Luc), mutant 3 (-1 087/+2-Luc), mutant 4 (-876/+2-Luc), mutant 5 (-745/+2-Luc), mutant 6 (-705/+2-Luc), mutant 8 (-613/+2-Luc), mutant 9 (-595/+2-Luc), mutant 10 (-403/+2-Luc) and mutant 11(-111/+2-Luc) were (90 012 +/- 2 445), (77 652 +/- 840), (149 927 +/- 4 915), (71 588 +/- 1 108), (99 283 +/- 2 612), (75 443 +/- 1 438), (282 772 +/- 7 046), (96 891 +/- 2 275), (148 917 +/- 5 966), (258 991 +/- 5 015) and (895 +/- 49) U, respectively. EMSA proved that activated protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB) can bind to the region of -403 to -111 bp; nuclear factor-1 (NF-1) and CCAAT/enhancer binding protein (C/EBP) can bind to the region of -705 to -613 bp; and upstream stimulatory factor (USF) can bind to the region of -745 to -705 bp. CONCLUSIONS: Two DNA regions -403 to -111 bp and -705 to -613 bp of GCLC gene, which can be bound by transcriptional factors such as NF-1, C/EBP, AP-1, and NF-kappaB on EMSA, are involved in positive gene regulation. A newly identified region -745 to -705 bp of GCLC gene, which can be bound by USF, is involved in negative gene regulation, suggesting that the interaction between E-box and USF can inhibit the expression of gamma-GCS.

5' Flanking Region↗

PubMed2005

[Effects of angiotensin II and aldosterone on NF-kappaB binding activity in hepatic stellate cells].

OBJECTIVE: To investigate the signal transduction mechanism underlying the effects of angiotensin II (AngII) and aldosterone (Aldo) on nuclear factor-kappaB (NF-kappaB) DNA binding activity. METHODS: Sixty male Wistar rats were randomly divided into 4 groups: model group (Mo group), injected with CCl(4) subcutaneously twice a week to establish a model of hepatic fibrosis; perindopril group (Pe group), injected with CCl(4) subcutaneously twice a week and perfused with perindopril once a day; losartan group (Lo group), injected with CCl(4) subcutaneously twice a week and perfused with losartan once a day; and control group (Nc group), injected with olive oil subcutaneously. The rats were killed in batches respectively 4 and 6 weeks after and their livers were collected to undergo Masson staining and be observed by light microscope. Electrophoretic gel mobility shift assay (EMSA) was used to detect the NF-kappaB DNA binding activity in the liver tissues. Western blotting was used to detect the expression of IkappaBalpha in the plasma protein. Hepatic stellate cells (HSCs)-T6 were cultured and preincubated for 1 h or not with U0126 (an inhibitor of MAPK/ERK kinase MEK), irbesartan (an AT-1 receptor blocker), and N-acetylcysteine (NAC, an antioxidant), angiotensin-converting enzyme inhibitor (ACEI), or tumor necrosis factor alpha (TNFalpha) prior to exposure to AngII or Aldo for 0.5 h, 1 h, 2 h, and 4 h respectively. The binding activities of NF-kappaB DNA were observed by EMSA. The expression of IkappaBalpha protein was detected with Western blotting. Histochemistry was used to detect the expression of NF-kappaB p65. RT-PCR was used to detect the expression of TNFalpha mRNA in HSC-T6 cells. RESULTS: The binding activity to NF-kappaB of the liver tissues was the strongest in the Mo group, followed by the Pe and Lo groups and Nc group. The IkappaBalpha expressions in liver tissues 4 and 6 weeks after the beginning of experiment in the Pe and Lo groups were significantly stronger than that in the Mo group (both P < 0.05). 0.5 hour after the intervention of AngII the DNA binding activity of the HSCs began to increase and peaked 1 hour later and then gradually decreased. The increase of NF-kappaB activity induced by AngII could be inhibited by irbesartan, ACEI and NAC pretreatment and could not be inhibited by U0126 pretreatment. Combined action of AngII and TNFalpha significantly increased the NF-kappaB DNA binding activity. The IkappaBalpha expression began to decrease 0.5 hour after the intervention of AngII and reached the lowest value 2 hours after. The expression of IkappaBalpha protein was increased by ACEI (P < 0.05), irbesartan and NAC (both P < 0.01). EMSA showed that 0.5 hour after the intervention of Aldo the DNA binding activity began to be increased and peaked by 1 hour and then began to be decreased. NAC, but not U0126 partly inhibited the increased of NF-kappaB activity induced by Aldo. Combined action of Aldo and TNFalpha significantly increased the NF-kappaB activity. Aldo increased the expression of IkappaBalpha protein in the HSCs at different time points (all P < 0.05). 0.5 hour after the AngII intervention the IkappaBalpha protein expression began to decrease and reach the lowest value 1 hour later and then began to increase 2 hours later. the IkappaBalpha protein expression was significantly decreased in the NAC and NAC+ Aldo intervention groups (both P < 0.05). There was no significant difference in IkappaBalpha protein expression between the Aldo intervention group and U0126 + Aldo, TNFalpha, and Aldo + TNFalpha treatment groups (all P > 0.05). Before stimulation, NF-kappaB was expressed in the plasma of HSCs, however, after the stimulation of AngII or Aldo for 1 hour it was expressed in the nuclei, and then transferred from the nuclei to the plasma 4 hours after the stimulation. However, little nuclear transfer was observed after pretreatment of NAC followed by AngII or Aldo intervention. The TNFalpha mRNA expression was significantly increased in the AngII and Aldo treatment groups in comparison with the control group (both P < 0.05). The TNFalpha mRNA expression was significantly weaker in the irbesartan + AngII, NAC + AngII, and ACEI groups in comparison with the AngII group (all P < 0.05). CONCLUSION: Stimulation of NF-kappaB activity mediates hepatic fibrosis induced by intrahepatic renin-angiotensin-aldosterone system (RAAS).

Aldosterone↗

PubMed2006

[Expression of nuclear factor-kappaB and its inhibitor in alveolar macrophages of patients with neonatal hyaline membrane disease].

OBJECTIVE: Inflammatory reaction and injury in immature lungs are associated with activation of nuclear factor-kappa B (NF-kappaB) to trigger proinflammatory cytokine release, but the mechanism thereof is not fully understood. The present study was conducted to understand possible relationship between expression of NF-kappaB and its inhibitor and severity and outcome of neonates with hyaline membrane disease (HMD). METHODS: Serial samples of bronchoalveolar lavage fluid (BALF) were obtained during mechanical ventilation from 31 preterm infants with HMD. These infants were divided into two groups: survivors group [n = 22, birth weight (1500 +/- 320) g and gestational age (31.2 +/- 1.8) weeks] and nonsurvivors group [birth weight (1340 +/- 280) g, gestational age (30.8 +/- 2.1) weeks]. Nineteen preterm infants [birth weight (1470 +/- 280) g, gestational age (30.6 +/- 1.9) weeks] without respiratory disorders were enrolled as control subjects. Alveolar macrophages (AM) were isolated by differential adherence. AM was cultured and treated with lipopolysaccharide (LPS) for 1 hr. Then, nuclear extracts of AM were analyzed by electrophoretic mobility shift assay (EMSA) for NF-kappaB expression. NF-kappaB inhibitor (IkappaB-alpha protein) in cytoplasmic extracts was detected by using Western blotting and IL-1beta and IL-8 in BALF by enzyme-linked immunosorbent assay (ELISA). RESULTS: NF-kappaB complexes were observed by EMSA, they were characterized by competition with cold oligonucleotide and p65-specific antibodies. The addition of an excess of cold oligonucleotide, corresponding to the NF-kappaB binding site, turned off the signal of the band, showing that the band was specific. An excess of an irrelevant oligonucleotide (corresponding to the SP-1) did not show any effect. The addition of an anti-p65 antibody caused the supershift of the two upper bands. After EMSA, the NF-kappaB complexes were quantified by using a ImageQuant software. NF-kappaB expression in AM at 24 hrs was higher in all the patients with HMD as compared with control subjects (survives/control, 34.1 vs 11.4 RDU, P < 0.01; nonsurvivors/control, 55.2 vs 11.4 RDU, P < 0.01). The NF-kappaB expression in AM at 72 hrs was higher than that in control subjects but not for nonsurvivors (survivors/control, 47.8 vs 25.6 RDU, P < 0.01; nonsurvivors/control, 21.8 vs 25.6, P > 0.05). The NF-kappaB expression in AM from nonsurvivors was depressed at 72 hrs as compared to 24 hrs (21.8 vs 55.2, P < 0.01), whereas the NF-kappaB expression in AM from survivors was still higher at 72 hrs than that at 24 hrs (47.8 vs 34.1, t = 4.43, P < 0.01). CONCLUSION: Altered NF-kappaB activation in AM of BALF of neonates with HMD was observed, and it may be mediated by decreased IkappaB synthesis, increased IkappaB degradation, or both. In HMD nonsurvivors NF-kappaB translocation was hampered upon LPS activation.

Birth Weight↗

PubMed1995

apobec-1, the catalytic subunit of the mammalian apolipoprotein B mRNA editing enzyme, is a novel RNA-binding protein.

Apolipoprotein B (apoB) mRNA editing is mediated by an enzyme complex which includes the catalytic subunit, apobec-1. Recombinant GST/APOBEC-1 binds with high specificity to a rat apoB RNA template as demonstrated by UV cross-linking and electrophoretic mobility shift assay (EMSA). ApoB RNA binding was competed by poly(U), poly(A,U), and tRNA, but not by poly(A) or other homopolymeric ribonucleotides. UV cross-linking of GST/APOBEC-1 to an apoB RNA template was uninfluenced by the binding of proteins of approximately 60 and approximately 44 kDa, present in S100 extracts prepared from different sources. The binding of these proteins was similarly uninfluenced by the simultaneous binding of GST/APO-BEC-1. Moreover, the inclusion of heterologous S100 extracts in the RNA binding reactions completely abrogated the competitive displacement of GST/APOBEC-1 by tRNA. EMSA revealed the onset of RNA binding within 1-2 min, and its specificity was confirmed by a supershift with anti-GST/APOBEC-1 antisera. The structural specificity for apoB RNA binding, as inferred from EMSA, appears to be distinct from apoB RNA editing since wild-type chicken apoB RNA, which is not editable, and several mutant chicken apoB RNAs containing clustered mutations within the minimal apoB RNA editing cassette, bound with efficiency similar to the rat apoB RNA template. In conclusion, while the data suggest that apobec-1 binds AU-rich templates, the importance of this observation in the context of mammalian apoB mRNA editing remains unknown.

APOBEC-1 Deaminase↗

PubMed1993

Antioxidant treatment of thymic organ cultures decreases NF-kappa B and TCF1(alpha) transcription factor activities and inhibits alpha beta T cell development.

Using electrophoretic mobility shift assays (EMSA), we have recently shown that nuclear extracts of 14-day mouse fetal thymocytes contain abundant NF-kappa B transcription factor activity. To determine the functional role of NF-kappa B in early thymocyte development, we have exposed fetal thymus organ cultures to inhibitors of NF-kappa B activation, namely the antioxidants N-acetyl-L-cysteine and butylated hydroxyanisole. Both compounds caused a dose-dependent arrest of thymocyte differentiation toward alpha beta, but not gamma delta, T cells. This was associated with a profound decrease in nuclear content of NF-kappa B and TCF1(alpha) transcription factor activity, as determined by EMSA. In contrast, NF-Y was affected less strongly, and cyclic AMP-response-element-binding protein levels remained essentially unchanged by antioxidants. To test the idea that alpha beta T cell development is correlated with NF-kappa B and TCF1(alpha) activity, we conducted additional experiments in a submersion culture system in which the generation of alpha beta T cells can be manipulated. Standard submersion culture supports gamma delta but alpha beta T cell development. Under these conditions, EMSA showed that transcription factor activities were similar to those seen in the presence of antioxidants. Importantly, when the generation of alpha beta T cells in submersion culture was restored by elevating oxygen concentrations, there was a dramatic increase in TCF1(alpha) activity, and both NF-kappa B and NF-Y returned to control levels. Taken together, these results strongly suggest that NF-kappa B and TCF1(alpha), presumably in concert with other transcription factors, play an important role in the development of alpha beta T cells.

Acetylcysteine↗

PubMed1999

Regulation of spontaneous and TNF/IFN-induced IL-6 expression in two human ovarian-carcinoma cell lines.

Autocrine and paracrine production of interleukin-6 (IL-6) is considered to be involved in the ongoing proliferation of ovarian-cancer cells. In view of the variability in IL-6 expression between various ovarian-cancer cells, we questioned whether differences in IL-6-gene regulation might be observed in ovarian tumor cells with and without IL-6 expression. The CAOV-3 cell line spontaneously secreted IL-6, which was enhanced by tumor necrosis factor-alpha (877 +/- 89 vs. 8,452 +/- 1,762 pg/ml, x +/- sd, p < 0.01). The electrophoretic mobility shift assay (EMSA) demonstrated that basic IL-6 expression was associated with DNA binding of activator protein-1 (AP-1) and nuclear factor IL-6 (NF-IL6). Nuclear factor kappa-B (NF-KB), which consisted mainly of p65-NF-KB was induced in response to TNF-alpha stimulation. A2780 cells did not express IL-6, either spontaneously or after stimulation with TNF-alpha. EMSAs, showed spontaneous AP-1 but no NF-IL6 or NF-KB DNA binding. TNF-alpha stimulation enhanced AP-1 and induced NF-KB but no NF-IL6 DNA binding in these cells. NF-IL6 protein, however, was detected in nuclear extracts of these cells by Western blotting. In contrast, IL-6-promoter transfection studies showed no difference in promoter activation between CAOV-3 and A2780. This study reveals that differential IL-6-gene expression observed in ovarian-cancer cell lines is independent of NF-IL6 activation.

DNA, Neoplasm↗

PubMed1998

Induction of stress response and differential expression of 70 kDa stress proteins by sodium fluoride in HeLa and rat brain tumor 9L cells.

We herein demonstrate that sodium fluoride (NaF) acts as a stress response inducer on HeLa and 9L rat brain tumor cells. NaF is only slightly cytotoxic, and inhibitory to Ser/Thr-phosphatases but not to Tyr-phosphatases in both cell lines. After treatment with 5 mM NaF for 2 h, the phosphorylation levels of vimentin and an alkali-resistant 65-kDa phosphoprotein were enhanced, a common phenomenon detected in cells under a variety of stress conditions. Under an identical treatment protocol, in which the cells were treated with 5 mM NaF for 2 h and then allowed to recover under normal growing conditions for up to 12 h, NaF differentially induced the cytoplasmic/nuclear heat-shock protein70s (including both the inducible and the constitutively expressed members of this protein family) in HeLa cells and the endoplasmic reticulum residing heat-shock protein70 (the glucose-regulated protein with an apparent molecular weight of 78 kDa) in 9L cells. Electrophoretic mobility shift assays (EMSA) using probes containing well-characterized regulatory elements revealed the activation of the heat-shock factor in HeLa but not in 9L cells; this is in good agreement with the stress protein induction pattern. Additional differential induction of binding activities toward EMSA probes individually containing NF-KB, AP-2, and CRE-like elements were detected in NaF-treated cells. The possible involvement of these binding sites as well as the corresponding factors in the stress response are discussed.

Animals↗

PubMed1999

DNA-binding properties of the ecdysteroid receptor-complex (EcR/USP) of the epithelial cell line from Chironomus tentans.

DNA-binding features of EcR and USP were investigated using a 0.4 M NaCl extract of the epithelial cell line of Chironomus tentans by means of electrophoretic mobility shift assays (EMSAs). It is shown that the DNA-binding is enhanced by hormone administration and that in the hormone dependent shift, both EcR and USP, are present. Furthermore, we demonstrate that under these conditions, EcR/USP form a unique complex on inverted repeat elements (PAL1 and hsp27-EcRE), while on direct repeat elements (DR1-5), a second complex with higher mobility is formed. In this second complex, neither EcR nor USP are present. Thus, an additional difference between PAL1 and DR-elements is the competition of other factors for DR-elements, modulating its function as an EcRE. A competition EMSA, using PAL1 as radiolabeled probe, reveals the following order of binding strength: PAL1>DR4/5>DR1>DR2/3/hsp27. Surprisingly, using DR1 as radiolabeled probe, shows a different order of binding strength: DR1>DR2>DR3/4/5/PAL1>hsp27. This indicates that the complexes formed on PAL1 are not identical to the ones formed on DR1 and that both are not easily convertible. Furthermore, the affinity of the EcR/USP complex may be altered under various conditions or by interaction with cofactors. Upon hormone administration, DNA binding of the receptor complex is enhanced, but the difference to hormone-free binding reactions decreases in course of time, indicating an additional hormone independent activation. Arch.

Amino Acid Sequence↗

PubMed2000

ATF and Jun transcription factors, acting through an Ets/CRE promoter module, mediate lipopolysaccharide inducibility of the chemokine RANTES in monocytic Mono Mac 6 cells.

The chemokine RANTES is produced by a variety of tissues, including cells of the monocyte/macrophage lineage. RANTES expression is rapidly and transiently up-regulated in primary monocytes and the monocytic cell line Mono Mac 6 in response to stimulation by the bacterial product lipopolysaccharide (LPS). Transient transfection of Mono Mac 6 cells with RANTES reporter-promoter deletion constructs, in conjunction with DNase I footprinting and heterologous reporter gene assays, allowed identification of an LPS-responsive region within the RANTES promoter. Electrophoretic mobility shift assays (EMSA), methylation interference and EMSA supershift experiments were used to characterize sequences and transcription factors responsible for this LPS inducibility. The region, termed RANTES site G [R(G)], contains consensus sites for Ets and CRE/AP-1-like elements. Site-directed mutagenesis of the Ets site resulted in a loss of only 15 % of promoter activity, while mutation of the CRE/AP-1 site led to a loss of 40 % of LPS-induced promoter activity. The Ets site constitutively binds the Ets family member PU.1. LPS stimulation leads to an induction of ATF-3 and JunD factor binding to the CRE/AP-1 site. Thus, LPS induction of RANTES transcription is mediated, in part, through the activation and selective binding of ATF and Jun nuclear factors to the R(G) promoter module.

Activating Transcription Factor 3↗

PubMed2000

Thapsigargin-induced grp78 expression is mediated by the increase of cytosolic free calcium in 9L rat brain tumor cells.

Exposure of 9L rat brain tumor cells to 300 nM thapsigargin (TG), a sarcoendoplasmic Ca(2+)-ATPases inhibitor, leads to an immediate suppression of general protein synthesis followed by an enhanced synthesis of the 78-kDa glucose-regulated protein, GRP78. Synthesis of GRP78 increases significantly and continues to rise after 4 h of treatment, and this process coincides with the accumulation of grp78 mRNA. TG-induced grp78 expression can be suppressed by the cytosolic free calcium ([Ca(2+)](c)) chelator dibromo-1, 2-bis(aminophenoxy)ethane N,N,N',N'-tetraacetic acid (BAPTA) in a concentration-dependent manner. Induction of grp78 is completely abolished in the presence of 20 microM BAPTA under which the TG-induced increase of [Ca(2+)](c) is also completely prevented. By adding ethyleneglycol bis(beta-aminoethyl)ether-N,N,N',N' tetraacetic acid in the foregoing experiments, in a condition such that endoplasmic reticulum calcium ([Ca(2+)](ER)) is depleted and calcium influx from outside is prevented, TG-induced grp78 expression is also abolished. These data lead us to conclude that increase in [Ca(2+)](c), together with the depletion of [Ca(2+)](ER), are the major causes of TG-induced grp78 expression in 9L rat brain tumor cells. By using electrophoretic mobility shift assays (EMSA), we found that the nuclear extracts prepared from TG-treated cells exhibit an increase in binding activity toward the extended grp78 promoter as well as the individual cis-acting regulatory elements, CRE and CORE. Moreover, this increase in binding activity is also reduced by BAPTA. By competitory assays using the cis-acting regulatory elements as the competitors as well as the EMSA probes, we further show that all of the tested cis elements-CRE, CORE, and C1-are involved in the basal as well as in the TG-induced expression of grp78 and that the protein factor(s) that binds to the C1 region plays an important role in the formation and maintenance of the transcription complex.

Animals↗

PubMed2000

N-acetylcysteine and endothelial cell injury by sulfur mustard.

Understanding the underlying mechanisms of cell injury and death induced by the chemical warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells (Toxicol. Appl. Pharmacol. 1996; 141: 568-583). Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFkappaB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFkappaB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 microM HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 microM buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 microM HD for 5-6 h. Externally applied GSH up to a concentration of 5 mM had no toxic effect on the cells. Mild toxicity was associated with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury. These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examined the hypothesis that HD may activate the nuclear transcription factor NFkappaB by performing EMSAs with nuclear extracts of endothelial cells following exposure to 0, 250 or 500 microM HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFkappaB binding to its consensus sequence induced by 500 microM HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFkappaB, although HD-induced activation of NFkappaB was partially suppressed by NAC at 5 h. Factor NFkappaB is an important transcription factor for a number of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFkappaB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFkappaB activity. The NFkappaB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction associated with the release of endothelial-derived cytokines.

Acetylcysteine↗

PubMed2002

Monitoring of single nicks in duplex DNA by gel electrophoretic mobility-shift assay.

We demonstrate that the gel electrophoretic mobility-shift assay (EMSA) can be used for site-selective and quantitative monitoring of nicks in linear double-stranded DNA (dsDNA) thus allowing to expediently follow the nicking activity of enzymes or other agents targeted to a designated dsDNA site. At elevated temperature and/or in the presence of urea, DNA fragments carrying a single nick produced by the nicking enzyme N.BstNBI exhibit a well-detectable gel retardation effect. On the basis of permutation analysis, the decreased electrophoretic mobility of nicked dsDNA fragments is attributed to a bend (or hinge) in the DNA double helix sequence-specifically generated by a nick. Since nick-induced DNA bending depends on interaction between base pairs adjacent to a nick, the change in mobility is different for nicked DNA sites with different sequences. Therefore, EMSA monitoring of differential mobility change caused by nicks within various DNA sequences could be useful for studying the differential base stacking and nearest-neighbor energetics.

DNA↗

PubMed2000

Enhanced expression and DNA binding activity of two CCAAT/enhancer-binding protein isoforms, C/EBPbeta and C/EBPdelta, in rheumatoid synovium.

OBJECTIVE: To investigate the activation and expression of CCAAT/enhancer-binding proteins (C/EBP), especially C/EBPbeta and -delta, in rheumatoid synovium, and their pathogenic implications in rheumatoid arthritis (RA). METHODS: The activation of C/EBPbeta and -delta was assessed in synovial tissues from patients with RA by electrophoretic mobility shift assay (EMSA); DNA binding activity of C/EBPs was evaluated by measuring EMSA band density. The expression and distribution of C/EBPbeta and -delta in synovial tissues were examined by immunohistochemistry analysis. As a control, synovial tissues from patients with osteoarthritis (OA) were studied. RESULTS: Enhanced DNA binding activity of C/EBPbeta and -delta, 2 major members of the C/EBP family, was detected in synovial tissues from RA patients, while synovial tissues from the patients with OA showed only faint or marginal activity (mean +/- SEM arbitrary units [AU] RA 23.3 +/- 11.7 in RA versus 4.5 +/- 1.3 in OA; P < 0.05). Moreover, the binding activities of the C/EBP proteins were correlated with both serum C-reactive protein levels (r = 0.62, P < 0.05) and synovial interleukin-6 messenger RNA levels (r = 0.60, P < 0.05). In immunohistochemistry studies, C/EBPbeta and -delta were detected predominantly in the rheumatoid synovial lining cells (both CD14+ and CD14- cells). CONCLUSION: C/EBPbeta and -delta may contribute to the pathology of rheumatoid synovitis.

Aged↗

PubMed2001

Regulation of CD95 (Fas/APO-1)-induced apoptosis in human chondrocytes.

OBJECTIVE: To examine the role of nuclear factor kappaB (NF-kappaB) and caspases 3, 8, and 9 in CD95-mediated apoptosis of normal chondrocytes. METHODS: First-passage chondrocytes from normal human knee cartilage were stimulated with CD95 antibody, and cell death was determined by annexin V binding and by an enzyme-linked immunosorbent assay. Activation of caspases 3, 8, and 9 was measured by Western blotting, and their role in death signaling was evaluated using caspase-specific small peptide inhibitors. The influence of NF-kappaB was determined by electrophoretic mobility shift assay (EMSA) and proteasome inhibition-dependent blocking of the degradation of inhibitor of NF-kappaB. RESULTS: Low levels of NF-kappaB activity were detected by EMSA in unstimulated chondrocytes. NF-kappaB activity was increased in response to agonistic CD95 antibody. CD95 antibody-induced apoptosis was potentiated by the proteasome inhibitors MG-132 and PS1, and this was associated with a reduced nuclear translocation of NF-kappaB. Proteasome inhibitors also caused the induction of DNA fragmentation by tumor necrosis factor alpha. Procaspase 3 processing was enhanced by the proteasome inhibitor MG-132. Procaspase 8 was undetectable by immunoblotting in whole cell lysates of chondrocytes, but caspase 8 messenger RNA was detected by reverse transcription-polymerase chain reaction. Furthermore, apoptosis induced by CD95 stimulation and proteasome inhibitors was blocked by the caspase 8-specific inhibitor Ac-IETD-CHO. Processing of procaspase 9 was not observed, and inhibition of CD95-dependent cell death by the caspase 9 inhibitor Ac-LEHD-CHO was not significant. CONCLUSION: These results suggest that CD95-dependent cell death is enhanced by NF-kappaB inhibition at and/or downstream of caspase 8 activation and that caspase 9 activation is not involved in CD95-mediated apoptosis in chondrocytes.

Antibodies↗

PubMed2001

Characterization of a prolactin gene polymorphism and its associations with systemic lupus erythematosus.

OBJECTIVE: Hyperprolactinemia is associated with systemic lupus erythematosus (SLE), but the mechanism is unknown. Prolactin is expressed in T lymphocytes and is under the control of an alternative promoter region. We characterized a G/T single-nucleotide polymorphism (SNP) at position -1149 of this promoter and assessed its prevalence in patients with SLE. METHODS: Electrophoretic mobility shift assays (EMSAs) were performed to determine DNA protein complex formation in the prolactin promoter. Transient transfection of reporter gene constructs containing the G/T promoter alleles into the Jurkat T cell line were used to determine transcription activity. Peripheral blood lymphocytes (PBLs) were treated in vitro with phytohemagglutinin (PHA) to determine levels of prolactin messenger RNA (mRNA). RESULTS: EMSAs indicated that binding of a GATA-related transcription factor was altered by the G/T SNP at position -1149. Transient transfection studies in Jurkat cells showed that the G allele consistently produced higher promoter activity. PHA treatment of PBLs in vitro induced a greater increment of prolactin mRNA from patients with the GG(-1149) genotype than from those with the TT(-1149) genotype. Disease association studies in a cohort of SLE patients demonstrated an increased frequency of the prolactin -1149 G allele compared with control subjects. CONCLUSION: We found a functionally significant polymorphism that alters prolactin promoter activity and mRNA levels in the lymphocytes. Altered local prolactin production by immune cells may contribute to disease progression by affecting T cell function.

Alleles↗