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:3.2.1.17 (lysozyme)
21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of the lysozyme gene in chicken macrophages is regulated by an enhancer located 2.7 kilobases upstream of the transcription start site. The organization of this enhancer was analyzed by in vitro assays (DNase I footprinting, dimethyl sulfate methylation protection, and band shift assays) and in vivo footprinting experiments. The results show that the enhancer contains four regions (I-IV) of protein-DNA interactions. First, transient gene transfer experiments demonstrate that region II contributes most to the enhancer function. This region contains a recognition site for the macrophage- and B cell-specific transcription factor PU.1, a member of the Ets transcription factor family. This site plays a major role in the enhancer since a mutation of this site abolishes enhancer activity. Second, in competition band shift experiments, we show that the only myeloid-specific complexes in regions I and II with nuclear factors are formed on the PU.1 recognition site by a member of the Ets transcription factor family. Third in in vivo footprinting experiments, the only sign of a protein-DNA interaction is a dimethyl sulfate-hyperreactive guanine 3'-adjacent to the PU.1 recognition site.
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PMID:Characterization of a myeloid-specific enhancer of the chicken lysozyme gene. Major role for an Ets transcription factor-binding site. 802 33

The distribution of myeloid lineage-associated cytokine receptors and lysosomal proteins was analyzed in human CD34+ cord blood cell (CB) subsets at different stages of myeloid commitment by reverse-transcriptase polymerase chain reaction (RT-PCR). The highly specific granulomonocyte-associated lysosomal proteins myeloperoxidase (MPO) and lysozyme (LZ), as well as the transcription factor PU.1, were already detectable in the most immature CD34+Thy-1+ subset. Messenger RNA (mRNA) levels for the granulocyte-colony stimulating factor (G-CSF) receptor, granulocyte-macrophage (GM)-CSF receptor alpha subunit and tumor necrosis factor (TNF) receptors I (p55) and II (p75) were also detected in this subset in addition to c-kit and flt-3, receptors known to be expressed on progenitor cells. By contrast, the monocyte-macrophage colony stimulating factor (M-CSF) receptor was largely absent at this stage and in the CD34+Thy-1-CD45RA- subsets. The M-CSF receptor was first detectable in the myeloid-committed CD34+Thy-l-CD45RA+ subset. All other molecules studied were found to be expressed at this stage of differentiation. Different cocktails of the identified ligands were added to sorted CD34+Thy-1+ single cells. Low proliferative capacity was observed after 1 week in culture in the presence of stem cell factor (SCF) + Flt-3 ligand (FL) + G-CSF. Addition of GM-CSF to this basic cocktail consistently increased the clonogenic capacity of single CD34+Thy-1+ cells, and this effect was further enhanced (up to 72.3 +/- 4.3% on day 7) by the inclusion of TNF-alpha. In conclusion, the presence of myeloid-associated growth factor receptor transcripts in CD34+ CB subsets does not discriminate the various stages of differentiation, with the exception of the M-CSF receptor. In addition, we show that TNF-alpha is a potent costimulatory factor of the very immature CD34+Thy-1+ CB subset.
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PMID:Analysis of myeloid-associated genes in human hematopoietic progenitor cells. 932 52

The protein product of the c-fes proto-oncogene has been implicated in the normal development of myeloid cells (macrophages and granulocytes). We have previously shown that 151 base pairs of c-fes 5'-flanking sequences are sufficient for myeloid cell-specific expression and include functional binding sites for Sp1, PU.1, and a novel nuclear factor (Heydemann, A., Juang, G., Hennessy, K., Parmacek, M. S., and Simon, M. C. (1996) Mol. Cell. Biol. 16, 1676-1686). This novel hematopoietic transcription factor, termed FEF (c-fes expression factor), binds to a cis-acting element that is located at nucleotides -9 to -4 of the c-fes promoter between two Ets binding sites (at -19 to -15 and -4 to +1) which bind PU.1. We now show that a FEF binding site exists in the myeloid cell-specific regulatory region of a second gene, the -2.7-kilobase pair enhancer of chicken lysozyme. The lysozyme FEF site is immediately 5' to a PU. 1 site, analogous to their arrangement in the c-fes promoter, and allows the formation of a preliminary FEF consensus site, 5'-GAAT(C/G)A-3'. This consensus site does not match any sites for known transcription factors. Importantly, although PU.1 binds immediately 3' of the FEF site in both the c-fes promoter and the chicken lysozyme enhancer (CLE), we show that they bind independently. The FEF sites are required for high levels of transcription by both the CLE and the c-fes promoter in transient transfection experiments. Importantly, elimination of the CLE FEF site abolishes all transcriptional activity of this enhancer element. Mutation of the adjacent PU.1 site in either the c-fes promoter or the CLE, reduces activity by approximately 50%. Therefore, transcription of both lysozyme and fes in myeloid cells requires FEF and PU.1. UV cross-linking experiments show that the FEF binding activity consists of a single 70-kDa protein in both human and murine cell lines. FEF binding activity is not affected by antibodies that specifically recognize a number of cloned transcription factors. Collectively, these data indicate that we have identified a novel transcription factor that is functionally important for the expression of at least two myeloid cell-specific genes.
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PMID:Expression of two myeloid cell-specific genes requires the novel transcription factor, c-fes expression factor. 936 14

During mouse embryogenesis, macrophage-like cells arise first in the yolk sac and are produced subsequently in the liver. The onset of liver hematopoiesis is associated with the transition from primitive to definitive erythrocyte production. This report addresses the hypothesis that a similar transition in phenotype occurs in myelopoiesis. We have used whole mount in situ hybridization to detect macrophage-specific genes expressed during mouse development. The mouse c-fms mRNA, encoding the receptor for macrophage colony-stimulating factor (CSF-1), was expressed on phagocytic cells in the yolk sac and throughout the embryo before the onset of liver hematopoiesis. Similar cells were detected using the mannose receptor, the complement receptor (CR3), or the Microphthalmia transcription factor (MITF) as mRNA markers. By contrast, other markers including the F4/80 antigen, the macrophage scavenger receptor, the S-100 proteins, S100A8 and S100A9, and the secretory product lysozyme appeared later in development and appeared restricted to only a subset of c-fms-positive cells. Two-color immunolabeling on disaggregated cells confirmed that CR3 and c-fms proteins are expressed on the same cells. Among the genes appearing later in development was the macrophage-restricted transcription factor, PU.1, which has been shown to be required for normal adult myelopoiesis. Mice with null mutations in PU.1 had normal numbers of c-fms-positive phagocytes at 11.5dpc. PU.1(-/-) embryonic stem cells were able to give rise to macrophage-like cells after cultivation in vitro. The results support previous evidence that yolk sac-derived fetal phagocytes are functionally distinct from those arising in the liver and develop via a different pathway.
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PMID:Differentiation of the mononuclear phagocyte system during mouse embryogenesis: the role of transcription factor PU.1. 1038 5

Expression of the chicken lysozyme gene is upregulated during macrophage maturation. Recently, an additional regulatory feature was discovered: the gene is differentially expressed in macrophages of embryonic/fetal and adult origin. The lysozyme gene is only weakly expressed in mature embryo-derived macrophages, whereas there is a high level of expression in macrophages derived from adult animals. This finding provided a molecular tool to investigate the heretofore ill-defined differences between embryonic/fetal- and adult-type macrophages. We showed that the low expression in the embryo is associated with reduced activity of the myeloid-specific -2.7 kb lysozyme enhancer. Our protein-binding analyses and transfection studies demonstrated that this enhancer, in order to be fully active in activated macrophages, requires the combined action of C/EBPs, PU.1, and a third, as yet unidentified, protein binding to an AP-1-like site. Of these three, PU.1 and C/EBPs display significantly reduced nuclear DNA-binding activities in embryo-derived macrophages compared with adult-type cells. These results point to different roles of C/EBPs and PU.1 in embryonic/fetal and adult myelopoiesis.
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PMID:Differential activity of the -2.7 kb chicken lysozyme enhancer in macrophages of different ontogenic origins is regulated by C/EBP and PU.1 transcription factors. 1046 59

Potential redundancy among members of the CCAAT/enhancer-binding protein (C/EBP) family in myeloid cells is indicated by the ability of C/EBPbeta to replace C/EBPalpha in vivo, by the expression of granulocyte colony-stimulating factor receptor (G-CSFR) on C/EBPalpha(-/-) cell lines, and by our finding that as with C/EBPalpha-estrogen receptor (C/EBPalpha-ER), either C/EBPbeta-ER or C/EBPdelta-ER can induce terminal granulopoiesis in 32D cl3 cells. To assess the consequences of globally inhibiting C/EBPs, we employed KalphaER, containing a Kruppel-associated box (KRAB) transrepression domain, the C/EBPalpha DNA-binding domain, and an ER ligand-binding domain. C/EBPs have a common DNA-binding consensus, and activation of KalphaER repressed transactivation by endogenous C/EBPs 50-fold and reduced endogenous G-CSFR expression. In 32D cl3 cells coexpressing exogenous G-CSFR, activation of KalphaER prevented and even reversed myeloperoxidase, lysozyme, lactoferrin, and C/EBPepsilon RNA induction by G-CSF. In contrast, induction of PU.1 and CD11b, a gene regulated by PU.1 but not by C/EBPs, was unaffected. A KalphaER variant incapable of binding DNA owing to an altered leucine zipper did not affect 32D cl3 differentiation. Transduction of KalphaER into murine hematopoietic progenitor cells suppressed the formation of granulocyte colony-forming units, even in cytokines that enable C/EBPalpha(-/-) progenitors to differentiate into neutrophils. The formation of macrophage and of granulocyte-macrophage colony-forming units were also inhibited, but erythroid burst-forming units grew normally. Thus, in 32D cl3 cells and perhaps normal progenitors, C/EBPs are required for granulopoiesis beyond their ability to induce receptors for G-CSF and other cytokines. One requisite activity may be activation of the C/EBPepsilon gene by C/EBPalpha, as either C/EBPalpha-ER or C/EBPbeta-ER rapidly elevated C/EBPepsilon RNA in 32D cl3 cells in the presence of cycloheximide but not actinomycin D.
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PMID:CCAAT/enhancer-binding proteins are required for granulopoiesis independent of their induction of the granulocyte colony-stimulating factor receptor. 1192 66

The -2.7 kb enhancer (E) element of the chicken lysozyme gene domain appears to govern expression of the gene in macrophages but not in oviduct tubular gland cells, the only other site of lysozyme expression. The ultimate goal of our research was to determine whether lysozyme domain variants could be developed that would mainly be expressed in the oviduct so that transgenic birds could be produced that would deposit exogenous protein in the egg white. Accordingly, precise mutations were made by poxvirus-mediated gene targeting in FEF/PU.1 and CCAAT/enhancer-binding protein (C/EBP) transcription factor binding sites in the -2.7 kb E of cloned copies of a specific lysozyme gene variant that includes a hydrophobic pentapeptide tail encoding sequence inserted immediately prior to the stop codon. This variant contains the entire lysozyme domain and is cloned in a lambda bacteriophage vector (lambdaDIILys-HT); the novel tail sequence enables distinction in cell-based expression systems between transcripts of the variant and those of the endogenous gene. These various lysozyme domain mutants, in bacteriophage vector form, were tested for expression in cultured chicken blastodermal cells cotransfected with plasmids encoding the transcription factors C/EBP and v-Myb. In the absence of these plasmids, barely detectable levels of endogenous lysozyme gene transcription resulted in the blastodermal cells. In the presence of the plasmids, however, transcripts of the endogenous gene could be detected as well as varying levels (as evaluated by quantitative real-time PCR) of transcripts of all of the lysozyme domain mutants. These results are discussed in the context of the known role and occurrence of various transcription factors involved in gene expression in differentiating macrophage cells. The ultimate test of expression of the variants in macrophages vs. oviduct cells will be to use them to produce transgenic birds.
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PMID:Analysis of an approach to oviduct-specific expression of modified chicken lysozyme genes. 1574 66

Interferon regulatory factor-8 (IRF-8)/interferon consensus sequence-binding protein (ICSBP) is a transcription factor that controls myeloid-cell development. Microarray gene expression analysis of Irf-8-/- myeloid progenitor cells expressing an IRF-8/estrogen receptor chimera (which differentiate into macrophages after addition of estradiol) was used to identify 69 genes altered by IRF-8 during early differentiation (62 up-regulated and 7 down-regulated). Among them, 4 lysosomal/endosomal enzyme-related genes (cystatin C, cathepsin C, lysozyme, and prosaposin) did not require de novo protein synthesis for induction, suggesting that they were direct targets of IRF-8. We developed a reporter assay system employing a self-inactivating retrovirus and analyzed the cystatin C and cathepsin C promoters. We found that a unique cis element mediates IRF-8-induced activation of both promoters. Similar elements were also found in other IRF-8 target genes with a consensus sequence (GAAANN[N]GGAA) comprising a core IRF-binding motif and an Ets-binding motif; this sequence is similar but distinct from the previously reported Ets/IRF composite element. Chromatin immunoprecipitation assays demonstrated that IRF-8 and the PU.1 Ets transcription factor bind to this element in vivo. Collectively, these data indicate that IRF-8 stimulates transcription of target genes through a novel cis element to specify macrophage differentiation.
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PMID:Identification of target genes and a unique cis element regulated by IRF-8 in developing macrophages. 1594 94

Expression profiling of haematopoietic cells is hampered by the heterogeneous nature of haematopoietic tissues and the absolute rarity of early unrestricted progenitors. To overcome this, the expression profile of lymphoid and myeloid-associated genes (LEF1, EBF, CD19, Sox-4, B29, CD45, C-fms, lysozyme, PU.1 and CD5) were investigated in 40 mouse myeloid haematopoietic precursors covering the entire haematopoietic hierarchy from multipotential to committed single lineages. The lineage-specific expression seen in single-cell studies was confirmed by examining fractionated bone marrow, whole tissues and differentiation of the multipotent cell line FDCP (Factor Dependent Cell Paterson) mix. Analysis of the 40 single myeloid precursors failed to detect expression of lymphoid-associated genes, LEF1, EBF, CD19 and CD5, despite detection in lymphoid cell controls. Surprisingly, the lymphoid-associated genes, Sox-4 and B29 were detected in the single myeloid precursors, which was confirmed in bone marrow and a multipotential myeloid cell line. The pattern of Sox-4 and B29, is consistent with a potential role in the commitment of bipotential granulocytic/macrophage precursors towards the granulocyte or macrophage lineage. In addition to providing baseline values for myeloid and lymphoid lineage markers during mouse haematopoiesis, these results highlight the importance of single-cell analysis in the study of complex tissues.
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PMID:Gene expression analysis of myeloid and lymphoid lineage markers during mouse haematopoiesis. 1692 95

A hybrid histiocytic sarcoma-interdigitating dendritic cell sarcoma was found in a small perinephric lymph node of an asymptomatic 80-year-old man, who presented a year ago with two small foci of lung metastasis found during routine chest X-ray. Fine needle aspiration cytology demonstrated interconnecting long and thin cell processes radiating from dendrite-like neoplastic cells with oval, enlongated, reniform, and irregular nuclei with vesicular chromatin and distinct nucleoli. Histology showed spindled epitheliod and histiocytic cells with abundant, slightly eosinophilic cytoplasm with indistinct cell borders and forming fascicles in a vague storiform pattern with interspersed T-lymphocytes. Immunohistochemically, the neoplastic cells were strongly positive for histiocytic markers: CD163, CD68, lysozyme, and PU.1, as well as strongly positive for dendritic cell markers: S100 and fascin, but were negative for CD1a (Langerhans cell marker), CD21/CD35 (follicular dendritic cell markers), B-cell, and T cell markers. This case is compared to the four hybrid histiocytic-dendritic sarcomas reported since 1983.
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PMID:Histiocytic sarcoma with interdigitating dendritic cell differentiation: a case report with fine needle aspiration cytology and review of literature. 1984 32


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