Sp1 binds to the G allele of the-1087 polymorphism in the IL-10 promoter and promotes IL-10 mRNA transcription and protein production.

Interleukin (IL)-10 is an important cytokine in immune regulation and promotes B-cell proliferation and antibody production. High levels of IL-10 were found in subjects with autoimmune diseases. The A to G single nucleotide polymorphism at -1087 of the IL-10 promoter is associated with differences in promoter activity and IL-10 production. The objectives of this study were to analyze differences in the transcription factor binding to the -1087 IL-10 gene polymorphism in B-cells, the influence of the A to G transition on the IL-10 and Sp1 gene expression in B-cells after lipopolysaccharide (LPS) stimulation and the effect of knockdown of Sp1 on IL-10 gene expression. Using B-cell lines obtained from subjects with GG and AA genotypes for the -1087 polymorphism and chromatin immunoprecipitation assay, we showed that the transcription factors PU.1 and Spi-B bound to both G and A alleles, whereas the transcription factor Sp1 only bound to the G allele. LPS stimulation of the B-cells resulted in a larger increase in IL-10 and Sp1 gene expression for GG genotypes than AA genotypes and knockdown of Sp1 gene expression resulted in a decrease in IL-10 mRNA transcription. IL-10 production was higher for the GG genotype than for the AA genotype.

Interferon gamma inhibits both proliferation and expression of differentiation-specific alpha-smooth muscle actin in arterial smooth muscle cells.

Differentiation of muscle cells is characterized morphologically by the acquisition of contractile filaments and characteristic shape changes, and on the molecular level by induction of the expression of several genes, including those for the muscle-specific alpha-actin isoforms. IFN-gamma is an inhibitor of proliferation for several cells, including vascular smooth muscle, and is also an inducer of differentiated properties for several hematopoietic cells. We have therefore investigated whether IFN-gamma affects the expression of alpha-smooth muscle actin in cultured arterial smooth muscle cells. Cells exposed to IFN-gamma show a reduction of alpha-smooth muscle actin-containing stress fibers, as detected by immunofluorescence. The effect was observed in all phases of the cell cycle, and was caused by a reduction of the synthesis of alpha-smooth muscle actin protein as revealed by two-dimensional electrophoretic analysis of actin isoforms. RNA hybridization using a cRNA probe that hybridizes to all actin mRNAs showed that IFN-gamma-treated cells have a reduced content of the 1.7-kb mRNA that codes for alpha-smooth muscle actin, and to a lesser extent, also of the 2.1-kb mRNA encoding the beta and gamma-cytoplasmic actins. The reduction of alpha-smooth muscle actin mRNA was confirmed using an alpha-smooth muscle actin-specific cRNA probe. The reduction of alpha-smooth muscle actin mRNA occurs within 12 h, and is dependent on protein synthesis, since cycloheximide treatment reversed the effect. The inhibition of this mRNA species was dose dependent, and detectable by RNA hybridization at a dose of 50 U/ml IFN-gamma. These results suggest that the differentiation of arterial smooth muscle cells is not necessarily coupled to an inhibition of cellular proliferation. Instead, IFN-gamma may regulate the expression of several genes that control both proliferation and expression of differentiation markers.

The Sp1 transcription factor binds to the G-allele of the -1087 IL-10 gene polymorphism and enhances transcriptional activation.

The objectives of this study were to evaluate the influence of the -1087 single nucleotide polymorphism (SNP) on the gene expression of interleukin (IL)-10 and to identify transcription factors binding to this site in B cells. Using electrophoretic mobility-shift assays and nuclear extract from the DG75 B-cell line, we demonstrated that the Sp1 transcription factor bound to the -1087 G-allele of the IL-10 promoter and that the transcription factors PU.1 and Spi-B bound to both the G- and A-alleles. Transient transfections showed that lipopolysaccharide stimulation resulted in a 15-fold increase in promoter activity for the G-allele as compared to a 6-fold increase for the A-allele. Co-transfection with Sp1 expression vector in Sp1-deficient SL2 cells leading to Sp1 binding to the G-allele of the -1087 SNP resulted in increased IL-10 promoter activity. The results suggest a role for Sp1 transcription factor in the activation of IL-10 through the G-allele of the -1087 SNP in response to inflammatory signals.

Expression of Epstein-Barr nuclear antigen 2 in kidney tubule cells induce tumors in transgenic mice.

The effect of EBNA2 in normal cells in vivo has not as yet been explored. The experiments described here were initiated to follow the consequences of the expression of EBNA2 in different tissues in transgenic mice. EBNA2 transgenic strains were generated using a vector containing EBNA2 encoding sequences under the control of the simian virus 40 (SV 40) early enhancer/promoter fused to the endogenous EBNA2 Wp promoter. Control mice carrying a transgene with the same sequence but lacking the EBV DNA part remained healthy during observation periods of up to 15 months. The SV-EBNA2 transgenic animals, however, over time developed abdominal masses that on necropsy showed to be due to kidney tumors. Histological examination revealed the presence of tumors with the morphology of kidney adenocarcinoma with a solid growth pattern. At the age of 20 weeks the kidneys of all animals investigated showed disseminated islands of tubular hyperplasia but no true malignant neoplasms. At about 50 weeks of age multiple foci of microscopic tubular adenocarcinomas were found in both kidneys. Eventually, tumors could be diagnosed in about 90% of the SV-EBNA2 transgenic mice. EBNA2-encoding RNA was expressed in both non-malignant kidney tissue and in tumors as shown by cDNA/PCR analysis. Immunoprecipitation and immunoblot analysis showed that the tumor cells contained a polypeptide of the same size as EBNA2 in B95-8 cells that reacted with a monoclonal anti-EBNA2 antibody. Immunohistochemistry demonstrated nuclear expression of EBNA2 in hyperplastic tubules and in tumor tissue.

Disease-related differences in antibody patterns against EBV-encoded nuclear antigens EBNA 1, EBNA 2 and EBNA 6.

Antibodies to Epstein-Barr virus (EBV) nuclear antigen family (EBNA) and three of its individual members, EBNA 1, EBNA 2 (A and B) and EBNA 6, were measured by anticomplement immunofluorescence (ACIF) in sera of 75 healthy controls, 13 patients with chronic EBV infection, 38 with non-Hodgkin lymphoma (NHL), 23 with Hodgkin's disease (HD), 105 with nasopharyngeal carcinoma (NPC) and 7 patients with infectious mononucleosis (IM). Their anti-EBV lytic antigens were also measured. We observed that: (1) anti-EBNA 2A and E6 rose in parallel 4-6 weeks after IM, followed by anti-EBNA 1 at 3-6 months, (2) all seropositive individuals had anti-EBNA 1; 74% also had anti-EBNA 2A and E6, (3) anti-EBNA 1 accounted for most of the anti-EBNA reactivity in non-IM sera. Striking disease-associated differences were noted on the humoral responses to the lytic and transformation-associated antigens. Compared to the controls, anti-EBNA 1, -EBNA 2A and -EBNA 6 were simultaneously four to 10 times higher in chronic reactivations, whereas only anti-EBNA 1 was elevated (10 times) in NPC. Individual EBNA titres were normal in NHL or HD patients.

Quantitative analysis of specific mRNA species in minute cell samples by RT-PCR and flow cytometry.

A method for the quantitative determination of specific mRNAs in small numbers of cells, freshly isolated from tissues or early cell cultures, was developed by combining quantitative reverse transcription-polymerase chain reaction (RT-PCR) and quantitative flow cytometry. Freshly isolated umbilical vein endothelial cells were sorted by flow cytometry and then lysed. The number of cells in the lysate was determined by counting of nuclei after propidium iodide staining using flow cytometry. The number of plasminogen activator inhibitor-1 (PAI-1) mRNA copies per cell was determined by quantitative RT-PCR using point-mutated PAI-1 cRNA as an internal standard. The cells were shown to contain 400-900 copies of PAI-1 mRNA molecules per cell which confirms that endothelial cells in vivo express PAI-1. PAI-1 mRNA expression was also analyzed in small numbers of endothelial cells in primary culture in basal conditions and after incubation with different interleukins. The method allowed reliable and reproducible estimation of the number of mRNA copies per cell from original cell samples containing less than 1000 cells. This method can be used for the quantitative determination of various mRNA species in specified cell populations from small tissue samples or cultured cells.

Regulation by GH of insulin-like growth factor-I mRNA expression in rat epiphyseal growth plate as studied with in-situ hybridization.

Expression of insulin-like growth factor I (IGF-I) mRNA and its dependence on GH was studied in rat epiphyseal growth plate by in-situ hybridization. Methodological aspects of the technique were first evaluated on fixed sagittal cryosections from 28-day-old rat epiphyseal growth plates to ascertain specific hybridization. In-situ hybridization was compared on sections from 10- and 28-day-old rats and the GH-dependence was studied in 35-day-old hypophysectomized rats. Expression of IGF-I mRNA was apparent in chondrocytes of the proliferative, hypertrophic and early degenerative zones of the growth plate of 28-day-old rats. The epiphyseal growth plate from 10-day-old rats showed a weak hybridization signal compared with 28-day-old rats. In contrast, the mesenchymal cells of the periosteum of 10-day-old rats showed a rather strong hybridization signal. Hypophysectomy resulted in a reduction in hybridization signal and cell number of the growth plate compared with 35-day-old age-matched normal rats. GH-Replacement therapy (200 micrograms GH s.c. every 4 h for 24 h) resulted in partially restored expression of IGF-I mRNA. The present study has shown that the IGF-I gene is expressed in the rat epiphyseal growth plate chondrocytes and that the expression is dependent on GH. The results support a paracrine/autocrine role of IGF-I for the expression of the stimulatory effect of GH on longitudinal bone growth.

Expression of the growth hormone-binding protein messenger RNA in the liver and extrahepatic tissues in the rat: co-expression with the growth hormone receptor.

A cDNA encoding a growth hormone-binding protein (GH-BP) was recently cloned from mouse and rat liver. The GH-BP in these species is identical to the extracellular part of the GH receptor (GH-R) with the transmembrane and intracellular domain substituted for a hydrophilic tail. In the present study the expression of the GH-BP and GH-R was studied in rat liver and extrahepatic tissues. Specific transcripts with estimated sizes of 1.2 kb (GH-BP) and 4.0 kb (GH-R) were found in the liver from both sexes. The expression of GH-BP increased with age up to puberty suggesting that it is developmentally regulated in a similar manner as GH-R. GH-BP mRNA was found in all extrahepatic tissues examined that contained GH-R mRNA. The ratio between the 1.2 kb and 4.0 kb transcripts varied between tissues indicating that GH-R and GH-BP transcripts may be separately regulated. The co-expression of GH-BP and GH-R suggests a functional role for the GH-BP in the local regulation of GH action.

High frequency of mammary adenocarcinomas in metallothionein promoter-human growth hormone transgenic mice created from two different strains of mice.

Transgenic mice were developed by injecting a mouse metallothionein promoter-human growth hormone (Mt-hGH) gene fragment into the pronucleus of C57Bl x DBA/2J-f2 or C57Bl x CBA-f2 one cell embryos. Six founder animals with the C57Bl x DBA genetic background grew 1.3-2.2 times larger than littermate controls and had higher levels of hGH in plasma (4.6-279 mU/l). Three of the four female transgenic founders developed malignant papillar adenocarcinomas of mammary origin at 27-43 weeks of age. One male transgenic founder was successfully mated and two of three female transgenic offsprings developed mammary tumors. To examine if the tumor induction was dependent on the strain of mice used the experiments were repeated using animals with different genetic background. Fourteen female hGH transgenic mice from five founder animals were generated using C57Bl x CBA-f2 mice. Thirteen of the animals had elevated levels of hGH in plasma (7-1960 mU/l) and grew larger than control animals. Nine of the animals developed mammary adenocarcinomas. Four of the hGH expressing animals did not demonstrate macroscopic tumor formation but have not yet been analyzed histologically. The present study suggests that markedly elevated endogenous levels of GH cause mammary carcinoma in hGH transgenic mice. The present animal model might prove useful for studying molecular mechanisms involved in the development of hormonally induced mammary tumors.

Increased frequency of a new polymorphism in the cell division cycle 2 (cdc2) gene in patients with Alzheimer's disease and frontotemporal dementia.

Recent studies show linkage between Alzheimer's disease (AD) and two loci on chromosome 10. The cell division cycle 2 (cdc2) gene is located close to one of the chromosome 10 markers, and is a candidate gene for AD since it is involved in the pathogenesis of AD. We sequenced coding exons and flanking intronic sequences and the promoter region on the cdc2 gene and found three new single nucleotide polymorphisms (SNPs). We analyzed 272 Caucasian AD cases, 160 controls and 70 cases with frontotemporal dementia (FTD) for these SNPs. Homozygosity for one of the SNPs (Ex6+7I/D) was more frequent in both AD and FTD cases than in controls. In the combined tauopathy (AD and FTD) group the odds ratio (OR) was 1.77 (95% CI 1.19-2.63) for the Ex6+7II genotype. Our findings suggest that the Ex6+7I allele is associated with tauopathies, both AD and FTD.

Interferon-gamma modulates the fibrinolytic response in cultured human endothelial cells.

The fibrinolytic potential of the endothelial cells gives important antithrombotic properties to the vascular wall. Thrombosis is a frequent complication to atherosclerosis and other conditions where inflammatory mediators are present in the vascular wall. Inflammatory agents like lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF alpha) have been demonstrated to modulate the expression of fibrinolytic factors in cultured endothelial cells. In the present study the expression of tissue-type plasminogen activator (t-PA), urokinase plasminogen activator (u-PA) and plasminogen activator inhibitors-1 and -2 (PAI-1 and PAI-2) antigen in conditioned medium from cultured human umbilical vein (HUVEC) and human saphenous vein (HSVEC) endothelial cells was investigated under basal conditions and after stimulation with LPS, TNF alpha, interferon-gamma (IFN-gamma) or interleukin-6 (IL-6) alone or in combinations. Stimulation with LPS or TNF alpha increased the expression of PAI-1, u-PA and PAI-2 in HUVEC and HSVEC, while the t-PA response differed between the two cell types. The effects of TNF alpha were modulated by IFN-gamma but not by IL-6. The increased expression of u-PA after stimulation with TNF alpha was reduced by IFN-gamma. In contrast, TNF alpha-induced expression of PAI-2 was synergistically increased by addition of IFN-gamma. These effects of IFN-gamma represent additional mechanisms by which inflammatory mediators may turn the fibrinolytic potential of the endothelium in a prothrombotic direction.

Expression of plasminogen activator inhibitor-1 mRNA in healthy, atherosclerotic and thrombotic human arteries and veins.

Plasminogen activator inhibitor-1 (PAI-1), specific inhibitor of plasminogen activators (PA), plays an important role in the regulation of fibrinolysis. Increased levels of PAI-1 have been associated with vascular disease such as thrombosis and atherosclerosis. In the present study the expression of PAI-1 mRNA in human healthy, atherosclerotic and thrombotic blood vessel walls was quantified by RNA-RNA hybridization in solution and localized by in situ hybridization. The mean expression of PAI-1 mRNA was significantly higher in healthy arteries (0.86 pg/microgram total RNA) than in healthy veins (0.29 pg/microgram total RNA), p < 0.01. The mean PAI-1 mRNA expression in thrombotic arteries (1.72 pg/micrograms total RNA) was significantly higher than that in healthy arteries, p < 0.05, and the mean PAI-1 mRNA expression in thrombotic veins (1.29 pg/micrograms total RNA) was significantly higher than that in healthy veins, p < 0.01. By in situ hybridization PAI-1 mRNA was detected in the intima, media and adventitia of healthy arteries and healthy veins. In atherosclerotic arteries PAI-1 mRNA was detected in the atherosclerotic plaque and in the medial and adventitial layers below the plaque. An increased expression of PAI-1 mRNA was found in the intimal layer of a thrombotic vein. The increased expression of PAI-1 mRNA in thrombotic arteries and veins indicates a role for PAI-1 in thrombogenesis.

Epstein-Barr virus shedding in breast milk.

One hundred healthy women already donating to the Children's Hospital Breast Milk bank consented to provide a sample of breast milk for this study. Using a DNA-DNA hybridization dot-blot assay Epstein-Barr virus (EBV) genome (Bam HIW region) was detected in cells shed into breast milk of 46 out of 100 women studied and in 60 out of 132 (46%) of samples donated overall. The prevalence of EBV shedding increased postnatally to a peak of 74% (26/35 positive samples) between 3 and 12 weeks postdelivery. Women delivering prematurely had an initially lower prevalence of shedding with only six out of 30 (20%) positive samples in the first week after delivery, compared to 16 out of 35 (46%) for women delivering at term. Of the 18 women donating more than one sample, 13 showed consistently positive (n = 8) or negative (n = 5) results, and the remaining five had intermittent shedding detected. Only seven out of 42 (17%) breast milk samples studied were EBV-IgG antibody positive, and none showed IgM or IgA-EBV antibodies. Further studies and prospective followup of infants are needed to confirm that breast milk is a significant source for early EBV infection of infants, as indicated by serologic studies.

Functional interaction of Oct transcription factors with the family of repeats in Epstein-Barr virus oriP.

The family of repeats (FR) is a major upstream enhancer of the Epstein-Barr virus (EBV) latent C promoter (Cp) that controls transcription of six different latent nuclear proteins following interaction with the EBV nuclear protein EBNA1. Here, it was shown that Cp could also be activated by octamer-binding factor (Oct) proteins. Physical binding to the FR by the cellular transcription factors Oct-1 and Oct-2 was demonstrated by using an electrophoretic mobility-shift assay. Furthermore, Oct-1 in combination with co-regulator Bob.1, or Oct-2 alone, could drive transcription of a heterologous thymidine kinase promoter linked to the FR in both B cells and epithelial cells. Cp controlled by the FR was also activated by binding of Oct-2 to the FR. This may have direct implications for B cell-specific regulation of Cp.

Transfer of the Epstein-Barr virus genes coding for small RNAs to human lymphoid cells with a vector carrying a dominant selectable marker.

Epstein-Barr virus (EBV)-negative, Burkitt-like lymphoma-derived cells were transformed with a transducing vector (pSV2-gpt) containing the Escherichia coli gene coding for xanthine-guanine phosphoribosyltransferase (XGPRT) and with a derivative of PSV2-gpt that carries the genes for the EBV-associated small RNAs on the EcoRI J fragment of B95-8 EBV DNA inserted at the unique EcoRI site (pJ-gpt). Cells transformed with PSV2-gpt and pJ-gpt express the E. coli gpt gene to approximately the same extent, judged by determinations of the XGPRT activity of cell extracts. Blot hybridisation experiments with restriction endonuclease-cleaved DNA from the transformants have revealed the presence of vector DNA sequences in the cells, at least some of which are most probably integrated into high mol. wt. chromosomal DNA. Northern blot hybridisation analysis of cytoplasmic RNA from pJ-gpt-transformed cells revealed the presence of an EcoRI J DNA complementary RNA species of the same size as the EBV DNA-encoded small RNAs found in EBV-transformed cells.

Identification of transcribed regions of Epstein-Barr virus DNA in Burkitt lymphoma-derived cells.

RNA was extracted from the Burkitt lymphoma-derived cell line Raji and from Burkitt lymphoma tumor biopsies, isotope labeled in vitro by iodination with 125I, and hybridized to electrophoretically separated restriction endonuclease fragments of Epstein-Barr virus DNA on nitrocellulose membranes. The results indicated that only certain parts of the Epstein-Barr virus genome are represented as polyribosomal RNA in Raji cells, with a pronounced dominance of RNA sequences complementary to a 2.0 x 10(6)-dalton segment of Epstein-Barr virus DNA located close to the left end of the viral genome. A map of virus-specific polyribosomal RNA sequences was constructed, which indicated that a minimum of three regions of the Epstein-Barr virus genome are expressed in Raji cells. Total-cell RNA preparations from five Burkitt lymphoma biopsies contained RNA sequences homologous to the same regions of Epstein-Barr virus DNA as polyribosomal RNA from Raji cells, albeit at different relative proportions.