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:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe a long-term, in vitro culture system initiated with CD34(+) or CD34(+)CD38(-) umbilical cord blood hematopoietic progenitors that supports normal human B-lineage development, including the production of mature Ig-secreting B cells. In the first stage (human B-progenitor long-term culture [HB-LTC]), CD34(+) hematopoietic progenitors are cultured on the murine stromal cell line, S17, leading to the sustained production of large numbers of CD10(+), CD19(+) early B progenitors. Reverse transcriptase-polymerase chain reaction (RT-PCR) and three-parameter flow cytometry for VpreB (surrogate light chain), cytoplasmic mu chain, and surface IgM expression were used to characterize the CD19(+) B progenitors present within these cultures. This analysis showed distinct B-lineage subpopulations, including pro-B cells, cycling pre-B cells, and IgM+, IgD-/+ immature B cells. The limited expansion of IgM+ B cells and the immature surface phenotype of this population (IgM+, IgD+, CD10(+), CD38(+)) suggested that HB-LTC conditions were unable to provide appropriate signals for further differentiation. A second culture stage was used to determine if these immature B cells were functionally competent. Purified CD19(+) cells were transferred onto fibroblasts expressing human CD40-ligand in the presence of IL-10 and IL-4. This lead to cell proliferation, modulation of the IgM+ cell surface phenotype to one consistent with an activated mature B cell, secretion of Ig, and isotype switching. Notably, IgM and IgG producing B cells were also generated using two-stage cultures established with highly purified multipotent CD34(+)CD38(-) hematopoietic stem cell progenitors. This culture model should permit detailed in vitro analysis and genetic manipulation of the major transition points in human B ontogeny, beginning with commitment to the B lineage and leading to development and activation of mature B cells.
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PMID:In vitro reconstitution of human B-cell ontogeny: from CD34(+) multipotent progenitors to Ig-secreting cells. 984 15

ICAM-1 is an Ig-like cell adhesion molecule expressed by several cell types, including the endothelium. Cross-linking of ICAM-1 on the surface of different cell types has previously been shown to cause an increase in cellular activation within the cytoplasm. In this study, we have compared signaling events following ligation of ICAM-1 by cross-linking with mAbs with events after activation of HUVEC by TNF. ICAM-1 cross-linking caused activation of Erk-1 and the AP-1 transcription factor complex, without any increase in NF-kappaB activity, in contrast to TNF stimulation. Transcription of VCAM-1 mRNA was observed by reverse-transcriptase PCR after ICAM-1 cross-linking, with no associated transcription of E-selectin. This was reflected by the presence of VCAM-1 protein after immunoprecipitation, without E-selectin expression, in ICAM-1 cross-linked cells. In contrast, mRNA and protein for both VCAM-1 and E-selectin were observed in TNF-treated HUVEC, as expected. Addition of the MEK (MAP/Erk kinase) inhibitor PD98059 reduced expression of VCAM-1 after ICAM-1 cross-linking, suggesting that the Erk pathway is involved in ICAM-1-mediated VCAM-1 expression. In conclusion, ICAM-1-induced expression of VCAM-1 represents a pathway for adhesion molecule up-regulation that is distinct from the TNF-induced pathway. It may be similar to the IL-4 pathway or it may represent a novel pathway.
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PMID:Ligation of ICAM-1 on endothelial cells leads to expression of VCAM-1 via a nuclear factor-kappaB-independent mechanism. 1007 50

Leukemia inhibitory factor (LIF), interleukin 6 (IL-6) and IL-8 are important regulators of inflammation and hematopoiesis. Human bone marrow stromal cells regulate marrow hematopoiesis by secreting cytokines. By using reverse-transcriptase polymerase chain reaction (RT-PCR), we demonstrate that human bone marrow stromal cells constitutively express LIF, IL-6 and IL-8 transcripts. By using specific ELISAs, we found that their spontaneous productions of LIF, IL-6 and IL-8 are elevated in response to serum and after stimulation with the pro-inflammatory cytokines IL-1alpha and TNF-alpha. The anti-inflammatory cytokine IL-4 reduces their serum- and cytokine-induced LIF secretion. By contrast, IL-4 stimulates their serum- and IL-1alpha-induced IL-6 synthesis. IL-4 has no effect on the serum-induced IL-8 synthesis by marrow stromal cells, but stimulates their cytokine-induced IL-8 production. The anti-inflammatory cytokine IL-10 has no effect on the serum- and cytokine-induced LIF, IL-6 and IL-8 synthesis by bone marrow stromal cells. RT-PCR experiments reveal the presence of IL-4 receptor alpha-chain mRNA and IL-10 receptor mRNA in cultured bone marrow stromal cells. The differential regulation by IL-4 of two related cytokines, such as LIF and IL-6, and the enhanced effect of this 'anti-inflammatory' cytokine on IL-6 and IL-8 synthesis highlight the tightly controlled regulation and the complexity of the cytokine production within the human bone marrow.
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PMID:Interleukin-4 (IL-4), but not IL-10, regulates the synthesis of IL-6, IL-8 and leukemia inhibitory factor by human bone marrow stromal cells. 1007 53

Nasopharyngeal carcinoma (NPC) is an epithelial cancer that is causally associated with Epstein-Barr virus (EBV) infection. NPC tumor biopsies are characterized histopathologically by an abundant infiltration of nonmalignant lymphocytes. We analyzed the expression of various cytokines in NPC tissues to investigate the interaction of the infiltrating lymphocytes and tumor cells. Analysis using reverse transcriptase-PCR revealed the expression of a panel of cytokines in the NPC biopsies: interleukin (IL)-1alpha, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-10, IFN-gamma, tumor necrosis factor-alpha, transforming growth factor-beta, and IL-1 receptor types I and II. Elevated expression of IL-1alpha and IL-1beta was observed in primary tumors and NPC metastases compared to control tissues. Interestingly, this increased expression correlated with the EBV-encoded viral IL-10 transcript. To determine which cells were responsible for producing IL-1, we determined the cellular constituents of NPC biopsies by immunoflow cytometric analysis. On the basis of data from these analyses, the three major specific cell populations, epithelial cells, CD4+ T cells, and CD8+ T cells, were selected from five NPC tumors using specific, antibody-coated paramagnetic beads. Reverse transcriptase-PCR of RNA from these fractionated cells showed that transcripts of IL-1alpha and IL-1beta were present not only in the malignant epithelial cells but also in CD4+ T cells infiltrating the tumor, a finding confirmed by immunohistochemical staining. We hypothesize that the unusual synthesis of IL-1alpha and IL-1beta by EBV-positive epithelial cells as well as by CD4+ T cells might contribute to lymphocyte infiltration and/or tumor growth during NPC development.
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PMID:Profile of cytokine expression in nasopharyngeal carcinomas: a distinct expression of interleukin 1 in tumor and CD4+ T cells. 1019 35

Although platelet-activating factor (PAF) receptors have been found on B lymphoblastoid cell lines, the action of PAF on freshly isolated human B cells has not been clearly demonstrated. Using a sensitive semiquantitative reverse-transcriptase PCR, we have found PAF receptor mRNA expressed by tonsillar B lymphocytes, but little in T lymphocytes. Examination of Percoll-fractionated tonsillar B cells indicated that the low density (primarily germinal center cells) and medium density fractions had approximately twofold more PAF receptor mRNA relative to the high density fraction. PAF (10-7 M) stimulated increases in intracellular Ca2+ that were consistently higher in the low and medium density B lymphocytes compared with high density cells. The PAF receptor antagonist Web 2170 inhibited this. Addition of PAF, but not lyso- or enantio-PAF, induced four- to sixfold greater synthesis of IgM and IgG in low and medium density cells compared with unstimulated controls, but had little effect on Ig production by high density cells. To investigate how PAF may influence Ig synthesis, PAF-stimulated B cells were examined for production of the Th2-type cytokines IL-4 and IL-13. PAF induced IL-4 and IL-13 mRNA expression in 17% of CD20+ cells, and IL-4 was detected in cell supernatants after 48-72 h of culture. Together, these data strongly suggest that functional PAF receptors are expressed on B cells in tonsils.
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PMID:Detection of functional platelet-activating factor receptors on human tonsillar B lymphocytes. 1022 30

The objectives of the present study were to characterize and compare the repertoire of cytokine-genes transcribed in skin homogenates obtained from normal dogs and dogs with atopic dermatitis (AD) using a reverse-transcriptase polymerase chain reaction and canine-specific cytokine-gene primers. Whereas IL-4 and IL-5 cytokine-gene transcripts were detected more commonly in atopic skin biopsy homogenates, IL-2 mRNA was amplified more often from normal control specimens. IFN-gamma mRNA was detected in 5/29 atopic specimens, 4 of them obtained from the only dog with chronic skin lesions. One-fourth of atopic samples exhibited clear type-2 cytokine profiles; the remainder did not demonstrate polarized repertoires. Conversely, type-1 cytokine profiles were characterized in one-fourth of normal control specimens. The present study establishes, for the first time, the transcription of type-2 cytokine-genes in the skin of dogs with AD. Future experiments investigating the cellular origin and dynamics of allergic cytokine-gene transcription are needed to confirm whether or not canine AD could be considered an immunological model for a human disease.
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PMID:Toward a canine model of atopic dermatitis: amplification of cytokine-gene transcripts in the skin of atopic dogs. 1038 38

The migration of Langerhans cells is an initial event in the sensitization phase of contact sensitivity. Langerhans cells travel from the epidermis to the regional lymph node, and can be variously modulated in the skin where many cytokines are released from epidermal cells, dermal cells, T helper (Th) cells, and other inflammatory cells during the sensitization and elicitation phase of contact dermatitis, and thus induce an altered inflammatory skin reaction. The modulatory effect of the cytokines released in the skin, such as IL-1beta, GM-CSF, and TNF-alpha as epidermal cytokines, IL-2, IL-12, and IFN-gamma as Th1 type cytokines, and IL-4 and IL-10 as Th2 type cytokines, was analyzed using the chemotactic chamber method in this study. Both GM-CSF and TNF-alpha induced the migration of human Langerhans cells in vitro, whereas IL-1beta, IL-2, IL-10, IL-12, and IFN-gamma had no effect on Langerhans cell migration. In contrast, IL-4 inhibited Langerhans cell migration in a dose dependent manner. The inhibitory activity of IL-4 was reversed by both anti-human IL-4 monoclonal antibody and anti-human IL-4 receptor monoclonal antibody. IL-4 inhibited the Langerhans cell migration induced by both TNF-alpha and GM-CSF. Furthermore, anti-TNF-RII monoclonal antibody inhibited both random migration and the migration induced by TNF-alpha, but not that induced by GM-CSF. A reverse-transcriptase-polymerase chain reaction and fluorescence-activated cell sorter analysis revealed that TNF-alpha up-regulated and IL-4 downregulated the TNF receptor II (TNF-RII) expression of Langerhans cells at both the mRNA and the protein levels. The pretreatment of Langerhans cells with TNF-alpha enhanced the migration of Langerhans cells and the expression of TNF-RII. After pretreating Langerhans cells with TNF-alpha, IL-4 inhibited both the migration of Langerhans cells and the expression of TNF-RII in a time dependent manner. These results indicate that IL-4 inhibits the migratory activity of Langerhans cells by downregulating the expression of TNF-RII in human Langerhans cells and thereby modulates the immune response in the skin.
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PMID:IL-4 inhibits the migration of human Langerhans cells through the downregulation of TNF receptor II expression. 1050 38

We investigated the role of IL-6 in myelin oligodendrocyte glycoprotein (MOG) peptide induced experimental autoimmune encephalomyelitis (EAE) using IL-6-deficient mice and found that IL-6-deficient mice were resistant to active induction of EAE, but that the treatment of those mice with IL-6 during the preclinical phase caused typical EAE. We also found that both wild-type and IL-6-deficient mice were resistant to passive transfer of EAE by lymphocytes from IL-6-deficient mice, but that passive transfer of lymphocytes from wild-type mice induced typical EAE in IL-6-deficient mice. Histological abnormalities of the central nervous system (CNS) in those IL-6-deficient mice with EAE were similar to those in wild-type mice with EAE. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed no difference in the production of inflammatory cytokines such as IL-1beta, IL-2, TNF-alpha, and IFN-gamma in the CNS of IL-6-deficient mice with EAE as compared to the CNS of wild-type mice with EAE. These results indicated that IL-6 might be an important factor in the induction phase, but might have little influence on the effector phase of EAE. We further estimated the production of cytokines in MOG-stimulated lymph node (LN) cells by enzyme-linked immunosorbent assay. Increased IL-4 and IL-10 production and reduced IL-2 and IFN-gamma production were observed in LN cells from IL-6-deficient mice as compared to LN cells from wild-type mice. These results suggested that a shift of T cell responses from Thl to Th2 might explain the resistance of IL-6-deficient mice to EAE. Taken together, IL-6 may play a crucial role in the induction phase of EAE by modulating Th1/Th2 balance.
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PMID:IL-6 plays a crucial role in the induction phase of myelin oligodendrocyte glucoprotein 35-55 induced experimental autoimmune encephalomyelitis. 1058 Aug 1

Substance P (SP) is an immunoregulatory tachykinin which augments antigen- and mitogen-induced lymphocyte proliferation via signaling through the neurokinin-1 receptor (NK1-R). Non-neuronal cells of the immune system such as monocytes, T lymphocytes and eosinophils can be a source of SP. We have investigated if antigen-presenting dendritic cells (DC) produce SP. DC were grown from bone marrow precursors using a cocktail of GM-CSF, IL-4 and Flt-3 ligand. Reverse transcriptase-PCR amplification using primers for the mouse preprotachykinin-A gene and direct DNA sequencing of amplified products from purified DC demonstrated the presence of the gamma-transcript of the gene, coding for SP and neurokinin A. At the protein level, mouse DC expressed SP as determined by an enzyme immunoassay and confirmed by immunostaining. The functional role of endogenous SP release was determined. During the interaction with syngeneic or allogeneic DC, the addition of a specific NK1-R antagonist partly reduced proliferation in responding T lymphocytes. This was confirmed by using responders derived from NK1-R-deficient mice. In the absence of DC, proliferation of T cells induced by direct TCR ligation and soluble CD28 was partly dependent on signaling through NK1-R, revealing an autocrine effect of SP production by T cells. In conclusion, these results demonstrate that endogenously produced SP contributes to T cell proliferation induced by DC or TCR / CD28 stimulation.
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PMID:Endogenously produced substance P contributes to lymphocyte proliferation induced by dendritic cells and direct TCR ligation. 1060 89

Using the reverse-transcriptase polymerase chain reaction (RT-PCR), cDNA encoding ovine (Ov) interleukin-4 (OvIL-4) was generated from mitogen-stimulated peripheral blood mononuclear cells (PBMC). Two identical clones generated from separate RT-PCR reactions differed from a published OvIL-4 sequence, although they had a high degree of identity with the bovine and human homologs. We show by sequence analysis that the OvIL-4 cDNA retained the four alpha-helix structure and disulfide bonds identified in human IL-4 (HuIL-4). Moreover, the cDNA encoding OvIL-4 was expressed in insect cells using the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) as a vector. Supernatants from insect cells infected with the recombinant virus secreted an additional protein with a relative molecular mass of 17,000. This protein was recognized by an anticervine IL-4 monoclonal antibody (mAb) in a Western blot and did not react with any proteins in supernatants from uninfected insect cells or cells infected with the wild-type AcMNPV. Supernatants from insect cells infected with the recombinant virus induced the proliferation of activated B cells in a dose-dependent manner and typically demonstrated 5 x 105 dilution U/ml of activity. However, OvIL-4 had no effect on the proliferation of resting T cells isolated from efferent lymph and actually inhibited the ability of a mitogen to stimulate these resting lymphocytes. In contrast, OvIL-4 induced the proliferation of mitogen-activated lymphoblast, demonstrating the complex role(s) OvIL-4 plays in the regulation of B and T cells.
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PMID:The expression and biologic effects of ovine interleukin-4 on T and B cell proliferation. 1080 77


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