Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The brain is an immunoprivileged organ isolated from the peripheral immune system. However, it has been shown that resident cells, notably astrocytes and microglia, can express numerous innate immune molecules, providing the capacity to generate a local antipathogen system. Perforin is a cytolytic protein present in the granules of cytotoxic T lymphocytes and natural killer cells. Expression in cells other than those of the hemopoetic lineage has not been described. We report here that fetal astrocytes in culture (passages 2 to 15), astrocytoma, and adult astrocytes expressed perforin. Reverse transcriptase polymerase chain reaction followed by Southern blot was carried out using multiple specific primers and all cDNAs were cloned and sequenced. Human fetal astrocyte perforin cDNA sequence was approximately 100% identical to the reported perforin cDNA cloned from T cells. Western blot analysis using monoclonal and polyclonal antiperforin peptide antibodies revealed a protein of 65 kD in both human fetal astrocyte and rat natural killer cell lysates (n = 4). Immunostaining followed by FACS(R) and confocal and electron microscopy analysis revealed that perforin was expressed by 40-50% of glial fibrillary acidic protein positive cells present in the fetal brain culture (n = 11). Perforin was not localized to granules in astrocytes but was present throughout the cytoplasm, probably in association with the endoplasmic reticulum. Perforin was not detected in normal adult brain tissue but was present in and around areas of inflammation (white and grey matter) in multiple sclerosis and neurodegenerative brains. Perforin-positive cells were identified as reactive astrocytes. These findings demonstrate that perforin expression is not unique to lymphoid cells and suggest that perforin produced by a subpopulation of astrocytes plays a role in inflammation in the brain.
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PMID:Identification of an astrocyte cell population from human brain that expresses perforin, a cytotoxic protein implicated in immune defense. 946 95

Phytohaemagglutinin stimulates lymphoid cells to initiate active cell division which is tightly coordinated with transcription of ribosomal RNA genes. Nuclear Run-On assays demonstrated that treatment of peripheral blood lymphocytes with PHA (10 microg/ml) resulted in maximal rRNA synthesis after 64 hrs. In contrast, mRNA levels for upstream binding factor (UBF)1 and UBF2, as measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blotting, increased relatively rapidly within 3 to 6 hrs. and remained elevated for at least the next 60 hrs. We further showed that exponentially growing cells of promyelocytic leukemia line HL-60 contained the same amounts of UBF1 and UBF2 mRNAs as phytohaemagglutinin (PHA)-stimulated lymphocytes for 6 hrs. Growth arrest of HL-60 cells, caused by 10 nM phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced monocytic/macrophage-like differentiation for 72 hrs., has been accompanied by a 50% decrease in UBF1/2 mRNAs expression. The lowest concentrations of UBF1/2 mRNAs were revealed in non-dividing terminally differentiated granulocytes. Regardless the activity of RNA polymerase I transcription and cell division rate, UBF1 mRNA levels prevailed over UBF2 mRNA levels in all human blood cell populations tested. Our results suggest that UBF gene expression is an important regulatory mechanism involved in the acceleration and possibly deceleration of rDNA transcription observed during mitogenic stimulation and inhibition of blood cells.
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PMID:Early gene expression of both RNA polymerase I transcription factors UBF1 and UBF2 precedes ribosomal RNA synthesis during lymphocyte mitogenic stimulation. 959 85

Resident macrophages have been suggested to participate in the initiation of beta cell damage during the development of autoimmune diabetes. The purpose of this study was to determine if the endogenous production and release of interleukin 1 (IL-1) in human islets of Langerhans by resident macrophages results in the inhibition of beta cell function. Treatment of human islets with a combination of tumor necrosis factor (TNF) + lipopolysaccharide (LPS) + interferon-gamma (IFN-gamma) stimulates inducible nitric oxide synthase (iNOS) expression, nitric oxide production, and inhibits glucose-stimulated insulin secretion. The IL-1 receptor antagonist protein (IRAP) prevents TNF + LPS + IFN-gamma-induced iNOS expression and nitrite production, and attenuates the inhibitory effects on glucose-stimulated insulin secretion by human islets. Inhibition of iNOS activity by aminoguanidine also attenuates TNF + LPS + IFN-gamma-induced inhibition of insulin secretion by human islets. These results indicate that the inhibitory effects of TNF + LPS + IFN-gamma are mediated by nitric oxide, produced by the actions of IL-1 released endogenously within human islets. Reverse transcriptase polymerase chain reaction was used to confirm that TNF + LPS + IFN-gamma stimulates the expression of both IL-1alpha and IL-1beta in human islets. Two forms of evidence indicate that resident macrophages are the human islet cellular source of IL-1: culture conditions that deplete islet lymphoid cells prevent TNF + LPS + IFN-gamma-induced iNOS expression, nitric oxide production, and IL-1 mRNA expression by human islets; and IL-1 and the macrophage surface marker CD69 colocalize in human islets treated with TNF + LPS + IFN-gamma as determined by immunohistochemical analysis. Lastly, nitric oxide production is not required for TNF + LPS + IFN-gamma-induced IL-1 release in human islets. However, cellular damage stimulates IL-1 release by islet macrophages. These findings support the hypothesis that activated islet macrophages may mediate beta cell damage during the development of insulin-dependent diabetes by releasing IL-1 in human islets followed by cytokine-induced iNOS expression by beta cells.
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PMID:IL-1 produced and released endogenously within human islets inhibits beta cell function. 969 Oct 88

Reciprocal communication between the immune system and the neuroendocrine system is mediated via a common chemical language of shared ligands and receptors. The neuropeptide substance P (SP) has been implicated as a mediator of immunomodulation. The evidence for substance P receptors on human lymphocytes is, however, controversial. The aims of the present study are to investigate substance P receptor (SPR) expression in human peripheral and mucosal mononuclear cells and to identify cellular sites of expression in human colonic mucosa. Using reverse-transcriptase PCR, we demonstrate that PBMC isolations are negative for SPR mRNA expression, whereas lamina propria mononuclear cell (LPMC) isolations express on average eight SPR mRNA transcripts per cell. In situ hybridization performed on surgically resected colonic tissue confirms the expression of SPR mRNA in LPMC in vivo. SPR mRNA signal was detected in LPMC, lymphoid follicles, and epithelium. The complementary technique of immunohistochemistry gave a similar distribution of SPR expression that colocalized with CD45 immunoreactivity. Dual-fluorochrome flow cytometry revealed SPR expression by CD4, CD45RO, CD45RA, CD8, CD19, and CD14 LPMC subsets, but not PBMC. Our findings suggest that SPR expression is distinctive of human colonic mucosal mononuclear cells and support a direct role for SP in mucosal immunomodulation.
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PMID:Substance P (neurokinin-1) receptor is a marker of human mucosal but not peripheral mononuclear cells: molecular quantitation and localization. 972 16

Enteric infection of mice with reovirus serotype 1 elicits antibody and cytotoxic T-lymphocytes in gut-associated lymphoid tissue (GALT). This led to the hypothesis that T-helper 1 (Th1) and T-helper 2 (Th2) responses develop in GALT. Reverse transcriptase-polymerase chain reactions on RNA from Peyer's patches (PP), intraepithelial lymphocytes (IEL), and lamina propria (LP) lymphocytes demonstrated that interferon (IFN)-gamma message was increased in PP and IEL, but not in LP following infection. No increase in mRNA for interleukin (IL)-4, IL-5, or IL-6 was detected. IFN-gamma, IL-5, and IL-6 were produced in in vitro cultures of PP 4-10 days postinfection. PP and spleen lymphocytes from infected mice produced IFN-gamma, but no IL-5 following in vitro restimulation. Infection also induced production of mRNA for the beta2 chain of the IL-12 receptor in PP. We conclude that reovirus induces robust Th1 and weak Th2 cell responses in GALT.
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PMID:T-Helper 1 and T-helper 2 cytokine responses in gut-associated lymphoid tissue following enteric reovirus infection. 974 58

Although hepatitis C virus (HCV) mainly affects hepatocytes, infection is widespread and involves immunologically privileged sites. Whether lymphoid cells represent further targets of early HCV infection, or whether other cells in the hematopoietic microenvironment may serve as a potential virus reservoir, is still unclear. We studied whether pluripotent hematopoietic CD34(+) cells support productive HCV infection and can be used to establish an in vitro infection system for HCV. Six patients were selected as part of a cohort of HCV chronic carriers who developed a neoplastic disease. Reverse transcriptase-polymerase chain reaction (RT-PCR) and branched DNA signal amplification assays were used to detect and quantitate HCV RNA in extracted nucleic acids from purified bone marrow and peripheral blood CD34(+) cells. Direct in situ RT-PCR, flow cytometry analysis, and immunocytochemistry were applied to demonstrate specific viral genomic sequences and structural and nonstructural virus-related proteins in intact cells. Results indicated that both positive and negative HCV RNA strands and viral proteins were present in CD34(+) cells from all HCV-positive patients and in none of the controls. Additional experiments showed that a complete viral cycle took place in CD34(+) cells in vitro. Spontaneous increases in viral titers indicated that virions were produced by infected hematopoietic progenitor cells. To further define the cellular tropism, we attempted to infect CD34(+) cells in vitro. We were unable to demonstrate viral uptake by cells. These findings suggest that HCV replication can occur in the early differentiation stages of hematopoietic progenitor cells, and that they may be an important source of virus production.
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PMID:Hepatitis C virus infection involves CD34(+) hematopoietic progenitor cells in hepatitis C virus chronic carriers. 978 70

Sequence-specific DNA-binding small molecules that can permeate human cells potentially could regulate transcription of specific genes. Multiple cellular DNA-binding transcription factors are required by HIV type 1 for RNA synthesis. Two pyrrole-imidazole polyamides were designed to bind DNA sequences immediately adjacent to binding sites for the transcription factors Ets-1, lymphoid-enhancer binding factor 1, and TATA-box binding protein. These synthetic ligands specifically inhibit DNA-binding of each transcription factor and HIV type 1 transcription in cell-free assays. When used in combination, the polyamides inhibit virus replication by >99% in isolated human peripheral blood lymphocytes, with no detectable cell toxicity. The ability of small molecules to target predetermined DNA sequences located within RNA polymerase II promoters suggests a general approach for regulation of gene expression, as well as a mechanism for the inhibition of viral replication.
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PMID:Inhibition of RNA polymerase II transcription in human cells by synthetic DNA-binding ligands. 978 80

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is an EGF family member expressed by numerous cell types that binds to EGF receptor 1 (HER-1) or 4 (HER-4) inducing mitogenic and/or chemotactic activities. Membrane-bound HB-EGF retains growth activity and adhesion capabilities and the unique property of being the receptor for diphtheria toxin (DT). The interest in studying HB-EGF in acute leukemia stems from these mitogenic, chemotactic, and receptor functions. We analyzed the expression of HB-EGF in L428, Raji, Jurkat, Karpas 299, L540, 2C8, HL-60, U937, THP-1, ML-3, and K562 cell lines and in primary blasts from 12 acute myeloid leukemia (AML) cases, by reverse-transcriptase polymerase chain reaction (RT-PCR) and Northern blot and by the evaluation of sensitivity to DT. The release of functional HB-EGF was assessed by evaluation of its proliferative effects on the HB-EGF-sensitive Balb/c 3T3 cell line. HB-EGF was expressed by all myeloid and T, but not B (L428, Raji), lymphoid cell lines tested, as well as by the majority (8 of 12) of ex vivo AML blasts. Cell lines (except for the K562 cell line) and AML blasts expressing HB-EGF mRNA underwent apoptotic death following exposure to DT, thus demonstrating the presence of the HB-EGF molecule on their membrane. Leukemic cells also released a fully functional HB-EGF molecule that was mitogenic for the Balb/c 3T3 cell line. Factors relevant to the biology of leukemic growth, such as tumor necrosis factor-alpha (TNF-alpha), 1alpha,25-(OH)2D3, and especially all-trans retinoic acid (ATRA), upregulated HB-EGF mRNA in HL-60 or ML-3 cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) induced HB-EGF mRNA and acquisition of sensitivity to DT in one previously HB-EGF-negative leukemia case. Moreover, the U937 and Karpas 299 cell lines expressed HER-4 mRNA. This work shows that HB-EGF is a growth factor produced by primary leukemic cells and regulated by ATRA, 1alpha, 25-(OH)2D3, and GM-CSF.
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PMID:Heparin-binding epidermal growth factor-like growth factor/diphtheria toxin receptor expression by acute myeloid leukemia cells. 1002 1

Earlier, we described a stromal cell-free two-step clonal culture system in which murine primitive lymphohematopoietic progenitors produce myeloid and B-lymphoid lineage cells. In the same culture T-cell potential of the progenitors was maintained. We now report that, in addition to myeloid and B-lymphoid cells, putative T-cell progenitors are also produced in culture. Lineage-negative (Lin-) Ly-6A/E+ c-kit+ bone marrow cells from 5-fluorouracil-treated mice were cultured in methylcellulose in the presence of SF (Steel factor), interleukin (IL)-11, and IL-7, and the resulting primary colonies were picked and pooled. When injected into severe combined immune deficiency (scid) mice, the pooled cells reconstituted the T-cell compartment of the scid mice earlier than freshly prepared primitive marrow cells. This reconstitution activity of the pooled primary colony cells was enriched in the Ly-6A/E+ and FcgammaRII/III-/low cell fractions. Reverse transcriptase-polymerase chain reaction (RT-PCR) and DNA-PCR analyses showed that some of the primary colony cells are differentiated sufficiently to express messenger RNA (mRNA) of T-cell receptor (TCR) beta-chain and pre-TCR alpha (pTalpha) and, although not frequently, to perform Dbeta-Jbeta rearrangement of the TCR gene. Micromanipulation studies confirmed the clonal origin of myeloid lineage cells and the cells positive for the T-cell-specific transcripts and D-J rearrangement of TCR beta-chain. These results suggested that, in the presence of SF, IL-11, and IL-7, primitive lymphohematopoietic progenitors differentiate toward T-cell lineage in addition to myeloid and B-cell lineages.
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PMID:Differentiation in culture of murine primitive lymphohematopoietic progenitors toward T-cell lineage. 1036 Nov 16

Livers transplanted across major histocompatibility complex (MHC) barriers in mice are normally accepted without recipient immune suppression, and induce a state of functional tolerance. However, markedly increasing functional dendritic cells (DC) in the 'passenger leucocyte' population by donor pretreatment with the hematopoietic growth factor Flt3-ligand (Flt3L; 10 microg/day for 10 days) results in acute allograft rejection. In this study, molecular, immunohistochemical and flow cytometric analysis of donor cell traffick into recipient lymphoid tissue 24 h after liver transplantation (C57BL/10 [H2b]-->C3H [H2k]) was performed. In addition, the capacity of donor-derived cells in these tissues to stimulate host T cell proliferation was examined. Reverse transcriptase polymerase chain reaction analysis revealed increases in donor genomic DNA in both thymi and spleens of mice given livers from Flt3L-treated donors compared to controls. Donor MHC class II+ (IAb+) cells in spleens were strikingly elevated (10-fold) in the former group. Two-colour flow cytometry revealed a similar increase in donor-derived H-2Kb+/I-Ab+ cells, and in the incidence of donor leucocytes expressing CD40, CD80, and CD86. CD11c+ DC comprised approximately 40% of the I-Ab+ cells in spleens of mice given livers from Flt3L-treated donors. These changes were associated with the presence, in spleens, of potent allostimulatory activity for naive recipient strain T cells, that was not observed in normal liver recipients. Elicitation of allograft rejection, associated with enhanced trafficking of stimulatory donor antigen-presenting cells (APC), in particular DC, suggests that normal liver graft survival and tolerance induction may be linked to failure/counter-regulation of APC-driven stimulation of effective anti-donor T cell responses.
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PMID:Trafficking of APC from liver allografts of Flt3L-treated donors: augmentation of potent allostimulatory cells in recipient lymphoid tissue is associated with a switch from tolerance to rejection. 1037 78


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