Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eosinophils are believed to injure tissues in a variety of allergic disease by virtue of their highly histotoxic contents and metabolites. They are readily observed in tissues during the allergic response yet the mechanisms governing the duration of tissue residence and route of removal remain obscure. We have previously reported in vitro and in vivo evidence that neutrophils undergo apoptosis (programmed cell death) and are recognized and ingested as intact cells by macrophages. We report that eosinophils, purified from the peripheral blood of asymptomatic healthy atopics, undergo apoptosis in vitro. After 72 to 96 h in culture, 57.0 +/- 6.2% (mean +/- SE) of the eosinophil population showed characteristic morphologic changes of apoptosis. Electrophoresis of the DNA from these cells demonstrated the typical "ladder" pattern of internucleosomal DNA cleavage, the hallmark of apoptosis-associated endonuclease activation. The rate of eosinophil apoptosis, slower than that reported for neutrophils, was delayed (by 80 +/- 6 h) in the presence of recombinant human IL-5, a cytokine previously reported to prolong eosinophil life in vitro but not known to modulate apoptosis. Aged, apoptotic eosinophils, but not fresh or aged preapoptotic eosinophils, were recognized and ingested as intact cells by macrophages. Apoptosis and ingestion by macrophages may represent a mechanism whereby the tissue longevity and removal of eosinophils is controlled.
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PMID:Apoptosis in human eosinophils. Programmed cell death in the eosinophil leads to phagocytosis by macrophages and is modulated by IL-5. 158 44

As demonstrated by long-range mapping of restriction endonuclease recognition sequences and genomic cloning, we found that the human genes encoding interleukin 3 (IL 3) and granulocyte/macrophage colony-stimulating factor (GM-CSF) are tandemly arrayed on the long arm of chromosome 5, separated by 9 kilobases (kb) of DNA. This close physical linkage of genes with similar structure and biologic function suggests that these cytokines may have evolved from a common ancestral gene. This linkage in evolution of two relatively divergent genes further implies that some of the other lymphokine and cytokine genes that appear to share as much or more sequence similarity than do IL 3 and GM-CSF may be distantly related members of a cytokine gene family.
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PMID:The human genes for GM-CSF and IL 3 are closely linked in tandem on chromosome 5. 283 32

Murine bone marrow-derived hemopoietic cells, dependent on interleukin (IL)-3 for their growth in culture, undergo programmed cell death, or apoptosis, upon cytokine withdrawal. The topoisomerase II inhibitor etoposide causes a more rapid onset of apoptosis in the IL-3-dependent cell line BAF3, deprived of IL-3. This acceleration of apoptosis by etoposide is prevented by inhibitors of RNA and protein synthesis and by the nucleases inhibitor aurintricarboxylic acid. The presence of IL-3 or overexpression of the oncogene bcl-2 caused a marked delay in the induction of apoptosis by etoposide, acting in a cooperative manner. The time at which the apoptotic program is irreversible is close to the induction of endonuclease activity as indicated by the effect of the delayed addition of either IL-3 or aurintricarboxylic acid on the onset of apoptosis, suggesting the importance of endonuclease activation in the development of apoptosis in hemopoietic cells.
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PMID:Interleukin-3 and Bcl-2 cooperatively inhibit etoposide-induced apoptosis in a murine pre-B cell line. 751 Feb 34

We developed and applied a quantitative competitive polymerase chain reaction method to study the expression of various cytokine genes in Con A-stimulated murine splenocytes. This method relies on the use of competitive templates that differ from the target cytokine cDNA templates only by the introduction of a unique restriction endonuclease site in the center of each competitive template. After same-tube amplification using a single pair of oligonucleotide primers for both the target and competitive templates, restriction with the unique endonuclease yields 2 species that are readily resolved on agarose gel electrophoresis: full-length target and half-length competitor fragments. Using this method, we studied the time course and effects of CsA and rapamycin on IL-2, IFN-gamma, IL-4, and IL-10 gene expression following Con A stimulation. IL-2, IFN-gamma, and IL-10 share a common pattern of gene expression peaking at approximately 6 hr, while IL-4 gene expression peaks later, at approximately 20 hr. CsA very effectively inhibits expression of IL-2, IFN-gamma, and IL-4, but it inhibits IL-10 expression only 65%. Rapamycin inhibits IL-10 gene expression 100% and is less effective inhibiting the other cytokines. This pattern of inhibition is consistent with a calcium and protein kinase C independent pathway for IL-10 gene regulation and supports the notion that CsA and rapamycin may be used together to advantage.
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PMID:Quantitative comparison of rapamycin and cyclosporine effects on cytokine gene expression studied by reverse transcriptase-competitive polymerase chain reaction. 751 20

Interleukin-6 (IL-6) is a multifunctional cytokine that plays an important role in host defense. It has been predicted that IL-6 may fold as a 4 alpha-helix bundle structure with up-up-down-down topology. Despite a high degree of sequence similarity (42%) the human and mouse IL-6 polypeptides display distinct species-specific activities. Although human IL-6 (hIL-6) is active in both human and mouse cell assays, mouse IL-6 (mIL-6) is not active on human cells. Previously, we demonstrated that the 5 C-terminal residues of mIL-6 are important for activity, conformation, and stability (Ward LD et al., 1993, Protein Sci 2:1472-1481). To further probe the structure-function relationship of this cytokine, we have constructed several human/mouse IL-6 hybrid molecules. Restriction endonuclease sites were introduced and used to ligate the human and mouse sequences at junction points situated at Leu-62 (Lys-65 in mIL-6) in the putative connecting loop AB between helices A and B, at Arg-113 (Val-117 in mIL-6) at the N-terminal end of helix C, at Lys-150 (Asp-152 in mIL-6) in the connecting loop CD between helices C and D, and at Leu-178 (Thr-180 in mIL-6) in helix D. Hybrid molecules consisting of various combinations of these fragments were constructed, expressed, and purified to homogeneity. The conformational integrity of the IL-6 hybrids was assessed by far-UV CD. Analysis of their biological activity in a human bioassay (using the HepG2 cell line), a mouse bioassay (using the 7TD1 cell line), and receptor binding properties indicates that at least 2 regions of hIL-6, residues 178-184 in helix D and residues 63-113 in the region incorporating part of the putative connecting loop AB through to the beginning of helix C, are critical for efficient binding to the human IL-6 receptor. For human IL-6, it would appear that interactions between residues Ala-180, Leu-181, and Met-184 and residues in the N-terminal region may be critical for maintaining the structure of the molecule; replacement of these residues with the corresponding 3 residues in mouse IL-6 correlated with a significant loss of alpha-helical content and a 200-fold reduction in activity in the mouse bioassay. A homology model of mIL-6 based on the X-ray structure of human granulocyte colony-stimulating factor is presented.
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PMID:Structure-function analysis of human IL-6: identification of two distinct regions that are important for receptor binding. 753 47

In the Tsukamoto-French model, ethanol causes an important 10-20-fold induction of ethanol-inducible cytochrome P4502E1 (CYP2E1), mediated through enzyme stabilization and increased rate of gene transcription. The CYP2E1 induction results in a pronounced increase in the rate of NADPH-dependent microsomal lipid peroxidation, an elevation which is not seen after simultaneous administration of the CYP2E1 inhibitor diallylsulfide. Increased amounts of lipid peroxides are seen in plasma and red blood cells of both rats and humans during high ethanol intake. A mechanism for ethanol-dependent liver damage is proposed which involves the CYP2E1-dependent lipid peroxide formation, either directly by its capability to induce NADPH-dependent peroxidation in the microsomal membranes or indirectly by a hypoxia-mediated transformation of xanthine dehydrogenase to xanthine oxidase, in activation of Ito cells and Kupffer cells to yield cytokine and collagen production. The CYP2E1 gene is polymorphic among Caucasians. Four different unrelated or partially linked polymorphisms have been observed. One polymorphism in the 5'-flanking region has been described to be associated with altered enzyme expression in vitro, and the rare allele was found to be less frequent among Swedish patients having lung cancer when compared to two different control groups. Another polymorphism, detectable with Dra I restriction endonuclease fragment length polymorphism (RFLP), was localized to intron 6, and the rare allele was less common among Italian alcoholics with clinical signs of liver cirrhosis, as compared to controls. Several other mutations in the CYP2E1 gene were found to be associated with this allele. However, further research is needed to relate the CYP2E1 gene polymorphism with incidence of liver cirrhosis.
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PMID:Ethanol-inducible cytochrome P4502E1: genetic polymorphism, regulation, and possible role in the etiology of alcohol-induced liver disease. 812 98

The cytokine cluster located on chromosome 5 has been shown by linkage studies to play a role in the genetic determination of circulating immunoglobulin E (IgE) levels in atopic subjects. In the study presented here, the reported chromosome 5 linkage has been investigated in two sets of subjects. The first consisted of a general population sample of 230 nuclear families (n = 1004) from Busselton, a small West Australian country town. The second group consisted of 124 unrelated atopic asthmatics and 59 unrelated non-atopic, non-asthmatic controls, all resident in the Oxfordshire Regional Health Authority area in the United Kingdom. A previously reported interleukin-4 (II-4) promoter polymorphism (-590 C-->T) was analysed in these populations by a newly designed method of specific PCR amplification and BsmFI restriction endonuclease digestion. In the Busselton population the polymorphism was shown to be weakly associated with specific IgE to house dust mite (Mann-Whitney-U test, p = 0.013) and to wheeze (MWU test, p = 0.029), but not with specific IgE to grass pollen, total serum IgE, bronchial hyperresponsiveness, eosinophil count, or asthma. In the Oxfordshire subjects there were no statistically significant associations with any measure of asthma or atopy. These data show that the -590 C-->T II-4 promoter polymorphism is only weakly associated with certain measures of asthma and atopy in some subjects. It was specifically not associated with serum IgE concentration or asthma in either of the two groups in this study.
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PMID:Investigation of an interleukin-4 promoter polymorphism for associations with asthma and atopy. 886 63

Ultraviolet light can affect the immune system locally as well as systemically leading to an impaired resistance to neoplastic cells and/or infections. Prior to the biological effect, UVB must be absorbed by a chromophore in the skin where it will give a signal that can lead to an altered immune response in the skin or elsewhere. These altered immune responses may be constituted by alteration in among others: cytokine profile, growth factors and costimulatory signals. Several hypotheses about the identity of the photoreceptor have been put forward. One photoreceptor in the skin is urocanic acid (UCA), that can isomerize from the trans- to the cis-isomer. The cis-isomer has immunosuppressive properties. Another photoreceptor is DNA that also efficiently absorbs UV wavelengths. After absorption the structure of the DNA molecule is altered. This alteration might lead to gene activation responsible for the immunotoxic outcome (altered gene expression). It has been demonstrated that the formation of DNA photoproducts by UV light is associated with the activation of many genes. Several studies indicate that UV-induced DNA damage, in the form of cyclobutyl pyrimidine dimers plays a role in UV-induced suppression of the immune system locally as well as systemically. In mice that were injected with liposomes containing the excision repair enzyme T4 endonuclease UVB-induced dimers were removed more efficiently as compared to control mice. In these mice UV-induced immunosuppression was prevented. Pilot studies by Kripke et al. indicated that the release of IL-IO and TNF alpha that are both induced by DNA damage might be involved. In preliminary studies with mice that were deficient with respect to DNA repair lower doses of UV were needed for the induction of immunosuppression as compared to their normal littermates. These studies indicate that altered gene expression plays a pivotal role in UVB-induced immunosuppression. In addition to a role for UCA and DNA in UV-induced immunosuppression it is postulated recently that signal transduction (EGF-receptor mediated upregulation of phospholipase A2) and transcription factors (NF kappa B, p91) are involved in UV-induced immunomodulation.
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PMID:Molecular aspects of UVB-induced immunosuppression. 907 98

In order to facilitate cytokine mRNA detection in blood cells, we have developed a highly reproducible and easily performed RNA isolation method for use with whole blood. Previously frozen human whole blood samples were lysed in guanidine thiocyanate solution to isolate total RNA. After reverse transcription a PCR method was applied to detect beta-actin and cytokine mRNA expression (interleukin-(IL)2, IL4, IL10, tumor necrosis factor alpha (TNF alpha) and interferon gamma (IFN gamma)). The presence of cDNA was confirmed by agarose gel electrophoresis and quantitated on-line using sequence-specific fluorochrome labeled internal oligonucleotide probes. This quantitative method is based on the cleavage of fluorescent dye labeled probes by the 5' --> 3' endonuclease activity of the Taq DNA polymerase during PCR and measurement of fluorescence intensity by a Sequence Detector System. The signal generated was directly proportional to the starting copy number of target molecules in the sample over 6 log concentrations and quantitative analysis of cDNA concentrations was performed in comparison to beta-actin or cytokine cDNA standards. mRNAs coding for beta-actin and TNF alpha were readily detectable in cDNAs prepared from the whole blood of eight healthy donors, while the other cytokines were expressed in lower amounts (IFN gamma, IL10) or were undetectable (IL2, IL4). The assay described is highly reproducible, requires no post PCR manipulation of the amplicons and permits the analysis of several hundred PCR reactions per day. Using this method it is possible to detect and quantify cytokine mRNA expression reliably in small amounts of previously frozen blood even after storage of samples for at least several months.
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PMID:Quantification of cytokine mRNA expression by RT PCR in samples of previously frozen blood. 952 Mar 2

Most strains of Helicobacter pylori from patients with peptic ulcer disease or intestinal-type gastric cancer carry cagA, a gene that encodes an immunodominant protein of unknown function, whereas many of the strains from asymptomatically infected persons lack this gene. Recent studies showed that the cagA gene lies near the right end of a approximately 37kb DNA segment (a pathogenicity island, or PAI) that is unique to cagA+ strains and that the cag PAI was split in half by a transposable element insertion in the reference strain NCTC11638. In complementary experiments reported here, we also found the same cag PAI, and sequenced a 39 kb cosmid clone containing the left 'cagII' half of this PAI. Encoded in cagII were four proteins each with homology to four components of multiprotein complexes of Bordetella pertussis ('Ptl'), Agrobacterium tumefaciens ('Vir'), and conjugative plasmids ('Tra') that help deliver pertussis toxin and T (tumour inducing) and plasmid DNA, respectively, to target eukaryotic or prokaryotic cells, and also homologues of eukaryotic proteins that are involved in cytoskeletal structure. To the left of cagII in this cosmid were genes for homologues of HsIU (heat-shock protein) and Era (essential GTPase); to the right of cagII were homologues of genes for a type I restriction endonuclease and ion transport functions. Deletion of the cag PAI had no effect on synthesis of the vacuolating cytotoxin, but this deletion and several cag insertion mutations blocked induction of synthesis of proinflammatory cytokine IL-8 in gastric epithelial cells. Comparisons among H. pylori strains indicated that cag PAI gene content and arrangement are rather well conserved. We also identified two genome rearrangements with end-points in the cag PAI. One, in reference strain NCTC11638, involved IS605, a recently described transposable element (as also found by others). Another rearrangement, in 3 of 10 strains tested (including type strain NCTC11637), separated the normally adjacent cagA and picA genes and did not involve IS605. Our results are discussed in terms of how cag-encoded proteins might help trigger the damaging inflammatory responses in the gastric epithelium and possible contributions of DNA rearrangements to genome evolution.
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PMID:Analyses of the cag pathogenicity island of Helicobacter pylori. 959 95


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