Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.21.1 (DNase)
 7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two DNase I-hypersensitive regions were identified downstream of the TCR gene constant region. One of these regions is located at the site of a putative enhancer element and was observed only in T cell lines and not in cell lines derived from other tissues. The other DNase-hypersensitive region was also detected only in T cell lines but only in those expressing TCR-beta RNA. Thus, the first region is probably tissue specific, while the second region is probably tissue and stage specific. The DNA sequence of the second DNase I-hypersensitive region revealed several stretches of nucleotides that are characteristic of consensus sequences for regulatory elements. These results, together with the observations in transgenic mice that indicate a requirement for two distinct regions for optimal TCR gene expression, suggest the presence of at least two regulatory regions downstream of the C-beta-2 region; one is an enhancer region and the other is a transcriptionally related regulatory region. The tissue/stage specificity of these DNase I-hypersensitive regions supports the notion that changes in chromatin structure control tissue-specific gene expression.
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PMID:T cell receptor beta gene has two downstream DNase I hypersensitive regions. Possible mechanisms of tissue- and stage-specific gene regulation. 252 73

To elucidate mechanisms that regulate ordered and tissue-specific assembly of Ig and TCR variable region gene segments, we have introduced a recombination substrate comprised of germline TCR beta V, D, and J gene segments into an Abelson murine leukemia virus-transformed pre-B cell line that actively rearranges endogenous Ig H chain variable region gene segments but does not rearrange endogenous light chain or TCR variable region gene segments. We find that these cells efficiently join D beta segments to J beta segments within the mini-locus, but that they do not make any detectable site-specific rearrangements of the introduced V beta segment even though it is closely linked in the same construct to the D beta. These findings suggest that factors necessary for V beta to (D beta)J beta joining may be absent in these pre-B cells and also imply that the order in which TCR V beta, D beta, and J beta segments are rearranged can be influenced by factors other than the 12/23 recombination rule. Furthermore, in agreement with the an accessibility model of VDJ recombinase control, the D beta region of the construct was found to be relatively more sensitive to DNAase I digestion in isolated nuclei when compared to the unrearranged V beta region.
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PMID:T cell receptor DJ but not VDJ rearrangement within a recombination substrate introduced into a pre-B cell line. 256 55

DNase/collagenase treatments are widely used to obtain single-cell suspensions of tumour cells and tumour-infiltrating T lymphocytes (TIL) from solid tumours. Since the functional integrity of such cells has been questioned, we have studied whether treatments with commonly used preparations of these enzymes could affect the expression of lymphocyte surface molecules and lymphocyte proliferative responsiveness. With peripheral-blood-derived T cells as a model, flow-cytometric analysis revealed strongly reduced expression of distinct CD molecules for each enzyme, notably CD2, CD4, CD8 and CD44 for DNase, and CD4, CD14, CD16, and CD56 for collagenase. The effects were found to be due to protease contaminations present in all but the purest enzyme preparations tested. Addition of serum or trypsin inhibitor abolished the effects. Since serum-free media are widely used to expand tumour-infiltrating T cells for clinical therapeutic use, data from early phenotypic analyses can be strongly misleading. Even after an 18-h rest period following the enzyme treatments, re-expression of the affected membrane markers was still far from complete. On the other hand, despite strongly reduced expression of CD2 molecules on the lymphocyte membrane, anti-CD2-induced proliferation was not affected, showing the redundancy of this signal molecule. Since other important T cell activation molecules (TCR, CD3, CD28) were not affected by enzymatic treatment, the use of expensive, highly purified collagenase/DNase preparations does not seem to be mandatory in clinical studies with expanded TIL.
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PMID:Reduced expression of distinct T-cell CD molecules by collagenase/DNase treatment. 816 20

In order to understand further the effects of Newcastle-disease-virus(NDV)-modified tumour vaccines we investigated the feasibility of isolating lymphocytes from the site of injection of patients undergoing postoperative active specific immunization (ASI) with autologous NDV-modified tumour cells. Delayed-type-hypersensitivity(DTH)-like reactions from five cancer patients were surgically removed, minced and the tissue particles were digested with collagenase and DNase. Lymphoid cells recovered were expanded in a highly efficient limiting-dilution analysis system optimized for T cell growth [Moretta et al. (1983) J Exp Med 157: 743] and lymphocyte microcultures (clonal probability > 0.8) could be grown for up to 1 year. Analysis of the microcultures for phenotype and function showed that the majority were positive for CD4 (92%) and TCR alpha beta (96%). Concanavalin-A-induced production of interleukin-2 (IL-2), IL-6, interferon gamma and tumour necrosis factor alpha was detected in more than 70% of the microcultures. Lectin-dependent cytotoxicity was only very rarely observed. The general characteristics of the microcultures obtained support the notion of a DTH-like reaction taking place at the site of tumour cell challenge. The possibility of in vitro expansion and cultivation of T lymphocytes from ASI vaccination sites should help to elucidate further the role of these cells in active specific immunization against autologous tumour cells.
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PMID:In vitro expansion and analysis of T lymphocyte microcultures obtained from the vaccination sites of cancer patients undergoing active specific immunization with autologous Newcastle-disease-virus-modified tumour cells. 834 63

TCR engagement of immature CD4(+)CD8(+) thymocytes induces clonal maturation (positive selection) as well as clonal deletion (negative selection) in the thymus. However, the cell death execution events of thymocytes during the negative selection process remain obscure. Using a cell-free system, we identified two different DNase activities in the cytosol of in vivo anti-TCR-stimulated murine thymocytes: one that induced chromosomal DNA fragmentation, which was inhibited by an inhibitor of caspase-activated DNase, and another that induced plasmid DNA degradation, which was not inhibited by an inhibitor of caspase-activated DNase. We purified the protein to homogeneity that induced plasmid DNA degradation from the cytosol of anti-CD3-stimulated thymocytes and found that it is identical with cyclophilin B (Cyp B), which was reported to locate in endoplasmic reticulum. Ab against Cyp B specifically inhibited the DNA degradation activity in the cytosol of anti-CD3-stimulated thymocytes. Furthermore, recombinant Cyp B induced DNA degradation of naked nuclei, but did not induce internucleosomal DNA fragmentation. Finally, we demonstrated that TCR engagement of a murine T cell line (EL4) with anti-CD3/CD28 resulted in the release of Cyp B from the microsome fraction to the cytosol/nuclear fraction. Our data strongly suggest that both active caspase-activated DNase and Cyp B may participate in the induction of chromosomal DNA degradation during cell death execution of TCR-stimulated thymocytes.
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PMID:Possible involvement of cyclophilin B and caspase-activated deoxyribonuclease in the induction of chromosomal DNA degradation in TCR-stimulated thymocytes. 1103 62

Locus control regions (LCRs) refer to cis-acting elements composed of several DNase I hypersensitive sites, which synergize to protect transgenes from integration-site dependent effects in a tissue-specific manner. LCRs have been identified in many immunologically important gene loci, including one between the TCRdelta/TCRalpha gene segments and the ubiquitously expressed Dad1 gene. Expression of a transgene under the control of all the LCR elements is T cell specific. However, a subfragment of this LCR is functional in a wide variety of tissues. How a ubiquitously active element can participate in tissue-restricted LCR activity is not clear. In this study, we localize the ubiquitously active sequences of the TCR-alpha LCR to an 800-bp region containing a prominent DNase hypersensitive site. In isolation, the activity in this region suppresses position effect transgene silencing in many tissues. A combination of in vivo footprint examination of this element in widely active transgene and EMSAs revealed tissue-unrestricted factor occupancy patterns and binding of several ubiquitously expressed transcription factors. In contrast, tissue-specific, differential protein occupancies at this element were observed in the endogenous locus or full-length LCR transgene. We identified tissue-restricted AML-1 and Elf-1 as proteins that potentially act via this element. These data demonstrate that a widely active LCR module can synergize with other LCR components to produce tissue-specific LCR activity through differential protein occupancy and function and provide evidence to support a role for this LCR module in the regulation of both TCR and Dad1 genes.
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PMID:Function and factor interactions of a locus control region element in the mouse T cell receptor-alpha/Dad1 gene locus. 1156 1

Exposure to soluble protein Ags in vivo leads to abortive proliferation of responding T cells. In the absence of a danger signal, artificially provided by adjuvants, most responding cells die, and the remainder typically become anergic. The adjuvant-derived signals provided to T cells are poorly understood, but recent work has identified BCL3 as the gene, of those tested, with the greatest differential transcriptional response to adjuvant administration in vivo. As an initial step in analyzing transcriptional responses of BCL3 in T cells, we have identified candidate regulatory regions within the locus through their evolutionary conservation and by analysis of DNase hypersensitivity. An evolutionarily conserved DNase hypersensitive site (HS3) within intron 2 was found to act as a transcriptional enhancer in response to stimuli that mimic TCR activation, namely, PHA and PMA. In luciferase reporter gene constructs transiently transfected into the Jurkat T cell line, the HS3 enhancer can cooperate not only with the BCL3 promoter, but also with an exogenous promoter from herpes simplex thymidine kinase. Deletional analysis revealed that a minimal sequence of approximately 81 bp is required for full enhancer activity. At the 5' end of this minimal sequence is a kappaB site, as confirmed by EMSAs. Mutation of this site in the context of the full-length HS3 abolished enhancer activity. Cotransfection with NF-kappaB p65 expression constructs dramatically increased luciferase activity, even without stimulation. Conversely, cotransfection with the NF-kappaB inhibitor IkappaBalpha reduced activation. Together, these results demonstrate a critical role for NF-kappaB in BCL3 transcriptional up-regulation by TCR-mimetic signals.
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PMID:NF-kappa B regulates BCL3 transcription in T lymphocytes through an intronic enhancer. 1453 Mar 44