Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The SCL gene is a member of the helix-loop-helix family of transcription factors. First identified because of its involvement in a rare chromosome translocation in human T cell acute lymphoblastic leukemia, it is now recognized to be involved in up to 25% of T cell leukemias. Normally within the hemopoietic system the gene is expressed in progenitor cells, erythroid cells, mast cells and megakaryocytes. During macrophage differentiation the level of SCL mRNA and protein becomes undetectable. To examine this further, SCL was over expressed in murine M1 cells. This resulted in perturbation of macrophage differentiation induced by leukemia inhibitory factor (LIF) and oncostatin-M (OSM) but not interleukin (IL)-6. Moreover the perturbation of LIF-induced differentiation applied to some components of macrophage differentiation but not others. This suggests that signaling through the gp130 homodimer (as occurs with IL-6) does not utilize an SCL-inhibitable pathway. In contrast the LIF receptor/gp130 heterodimer does utilize an SCL-inhibitable pathway for some elements of macrophage differentiation (e.g., lysozyme induction) but not others (e.g., M-CSF receptor induction).
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PMID:The SCL transcription factor and differential regulation of macrophage differentiation by LIF, OSM and IL-6. 769 58

The physiologic program of macrophage differentiation normally proceeds in a coordinated manner in response to several different growth factors. Although the utilization of common receptor subunits may explain in part overlapping biologic functions, mechanisms by which unique actions are mediated remain obscure. We examined growth factor-induced macrophage differentiation in M1 leukemia cells that simultaneously display receptors for interleukin-6 (IL-6), leukemia inhibitory factor (LIF) and Oncostatin-M (OSM). Differentiation induced by all three factors was associated with decreased expression of transcription factors myb and SCL, increased expression of macrophage markers, and suppression of proliferation. Cell lines were established in which SCL expression was enforced. In the absence of growth factors, cells were indistinguishable from parental cells. However, LIF (or OSM)-induced macrophage differentiation was perturbed; there was failure to undergo morphologic differentiation, disturbed expression of lysozyme and Mac1 alpha, and failure to suppress proliferation. Surprisingly the perturbation of macrophage differentiation did not apply to induced expression of macrophage colony-stimulating factor (M-CSF) or granulocyte colony stimulating factor (G-CSF) receptors. This dissociation of elements normally coordinated in a macrophage differentiation program applied at a clonal level. There was no disturbance of IL-6-induced macrophage differentiation. These data directly implicate SCL in components of the macrophage differentiation program (suggesting that LIF receptor/gp130 heterodimers utilize an SCL-inhibitable pathway while gp130 homodimers do not) and demonstrate differential-regulation of components of the mature macrophage phenotype.
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PMID:Differential regulation of macrophage differentiation in response to leukemia inhibitory factor/oncostatin-M/interleukin-6: the effect of enforced expression of the SCL transcription factor. 781 94

Hematopoietic growth factors may be useful in improving the clinical effectiveness of arabinofuranosylcytosine (ara-C). In vitro studies have indicated that interleukin 3(IL-3) and, to a lesser extent, granulocyte-macrophage colony-stimulating factor (GM-CSF), but not G-CSF or M-CSF, may be capable of specifically augmenting the ability of ara-C to kill leukemic myeloid cells by pharmacological and cytokinetic mechanisms including increase of intracellular ara-CTP/dCTP pool ratios and enhanced ara-C DNA incorporation in leukemic blast cells, decrease of IC 90 of ara-C for leukemic colony-forming cells (CFC) as compared with normal CFC growth, and recruitment of quiescent leukemic cells into the cell cycle. In contrast, the combination of ara-C with M-CSF or with the leukemia inhibitory factor (LIF) appears to be useful in overcoming the block in differentiation of leukemic blast, while the effects of GM-CSF and IL-3 on ara-C-induced differentiation appear limited. The combined treatment of human myeloid leukemia cells by ara-C and LIF is associated with down-regulation of c-myc gene expression, transcriptional activation of jun/fos gene expression, and features of functional differentiation (e.g., the capability to reduce nitroblue tetrazolium, to express lysozyme, or to display differentiation-related surface receptors including C3bi and the c-fms protein). On the basis of these in vitro studies first clinical trials are underway that are examining the efficacy of ara-C combinations with these molecules for the treatment of myeloid disorders.
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PMID:Modulation of cytotoxicity and differentiation-inducing potential of arabinofuranosylcytosine in myeloid leukemia cells by hematopoietic cytokines. 846 21

Myeloid leukemia M1 cells can be induced for growth arrest and terminal differentiation into macrophages in response to interleukin 6 (IL-6) or leukemia inhibitory factor (LIF). Recently, a large number of cytokines and growth factors have been shown to activate the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway. In the case of IL-6 and LIF, which share a signal transducing receptor gp130, STAT3 is specifically tyrosine-phosphorylated and activated by stimulation with each cytokine in various cell types. To know the role of JAK-STAT pathway in M1 differentiation, we have constructed dominant negative forms of STAT3 and established M1 cell lines that constitutively express them. These M1 cells that overexpressed dominant negative forms showed no induction of differentiation-associated markers including Fc gamma receptors, ferritin light chain, and lysozyme after treatment with IL-6. Expression of either c-myb or c-myc was not downregulated. Furthermore, IL-6- and LIF-mediated growth arrest and apoptosis were completely blocked. Thus these findings demonstrate that STAT3 activation is the critical step in a cascade of events that leads to terminal differentiation of M1 cells.
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PMID:STAT3 activation is a critical step in gp130-mediated terminal differentiation and growth arrest of a myeloid cell line. 863 98

Cells of the M1D+ murine myeloid leukemic cell line differentiate into macrophages in response to either leukemia inhibitory factor (LIF) or interleukin 6. Previously, it was shown that LIF treatment of M1D+ cells leads to an increased expression of colony-stimulating factor (CSF) receptor mRNA encoded by c-fms. CSF-1, a macrophage growth factor, induces the survival, growth, and differentiation of mononuclear phagocytes but has not been implicated in the regulation of early myeloid cell differentiation. Here we show that low-dose LIF treatment of M1D+ cells results in CSF-1 secretion and CSF-1 receptor up-regulation. CSF-1, when applied alone, induces some M1D+ adherence and the up-regulation of lysozyme M, a macrophage-specific marker. Finally, we show that when applied together, LIF and CSF-1 act synergistically to induce macrophage morphology, phagocytosis, and the expression of the macrophage-specific markers CD11b/Mac-1 alpha chain, lysozyme M, FcgammaRII, and JE/MCP.1. These results indicate that instead of being part of exclusive pathways, as thought until this work, LIF and CSF-1 can function synergistically to further stimulate the early stages of myeloid differentiation.
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PMID:Synergistic effects of colony-stimulating factor 1 and leukemia inhibitory factor in inducing early myeloid cell differentiation. 983 Dec 45