Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proto-oncogene Bcl-2 is normally expressed in B lineage cells in a stage specific manner and extends cell survival. Deregulated Bcl-2 expression has been shown to cause a major expansion in surface IgM and IgD positive B cells. In this report, the influence of deregulated expression of Bcl-2 on the VH repertoire of B cells was studied. This was accomplished by stimulating B cells from both adult and fetal Bcl-2-Ig transgenic mice and their normal littermates using the polyclonal activator lipopolysaccharide. Activated cells were then analyzed by in situ hybridization using radiolabeled C mu and VH gene probes. The D-proximal VH families 7183 and Q52 were preferentially expressed in the adult transgenic mice compared to their normal littermates. VH 7183 and Q52 were also over-represented in fetal transgenic mice but not to a greater extent than that observed with normal fetuses. These results demonstrate that the overproduction of Bcl-2, which prolongs cell survival independent of affecting proliferation, substantially alters the VH gene repertoire.
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PMID:Skewed B cell VH family repertoire in Bcl-2-Ig transgenic mice. 177 25

We characterized the basis for the follicular lymphoproliferation in transgenic mice bearing a Bcl-2-immunoglobulin (Bcl-2-Ig) minigene representing the t(14;18) of human follicular lymphoma. Discriminatory S1 nuclease protection assays revealed that the Bcl-2-Ig transgene was overexpressed relative to endogenous mouse Bcl-2 in spleen and thymus. Western (immunoblot) analysis demonstrated the overproduction of the human 25-kilodalton Bcl-2 protein, which arose from the transgene, in spleen, thymus, and the expanded B-cell subset. Despite the generalized lymphoid pattern of deregulation, two-color flow cytometry and density gradient centrifugation indicated that the expanded lymphocytes were predominantly small, resting B cells coexpressing B220, immunoglobulin M (IgM), IgD, Ia, and kappa. Cell cycle analysis confirmed that about 97% of these expanded B cells reside in G0/G1. An extensive characterization of transgenic lines revealed a fourfold excess of IgM-IgD-expressing B cells in spleen and dramatically increased numbers in bone marrow. While resting, these cells proliferated in response to lipopolysaccharide and anti-IgM and demonstrated normal B-cell colony formation in soft agar. Moreover, these B cells, which demonstrated an extended survival in vitro even in the absence of stroma, were also resting in G0, yet were capable of proliferative responses. These findings provide consistent evidence that the accumulation of B cells after Bcl-2 overproduction is secondary to prolonged cell survival and not increased cell cycling. This suggests a unique role for Bcl-2 as a proto-oncogene that enhances cell survival independent of promoting cell division.
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PMID:Deregulated Bcl-2-immunoglobulin transgene expands a resting but responsive immunoglobulin M and D-expressing B-cell population. 218 11

Here we report a survey of c-rel proto-oncogene transcription in murine tissues, cell lines and lymphoid cells. In addition to the previously described 7.5-kb mRNA, we have identified a mRNA of 2.5-kb. As DNA hybridization indicates that there is only one gene with significant homology to c-rel in the mouse genome, it appears that multiple mRNAs are transcribed from c-rel. The nucleotide sequence of a cDNA clone derived from the 2.5-kb c-rel mRNA demonstrates that the 7.5- and 2.5-kb mRNAs encode identical proteins. The different size of the two mRNAs is due to variation in the length of the 3' untranslated region, which arises from the use of alternate polyadenylation signals. These mRNAs are present at low levels in organs tested, and in cell lines representing a wide variety of lineages. Fibroblasts are the only cells in which expression was not detectable. In B-cell lines representing different stages of differentiation, the highest levels of mRNA are seen in B-lymphomas, and this level drops markedly in plasmacytomas. There is a transient increase of 10- to 20-fold in the level of c-rel mRNAs in T-cells treated with concanavalin A, while lipopolysaccharide-stimulated B-cells exhibit a transient 5-fold elevation of c-rel expression. This study indicates that the control of c-rel expression can vary between and within different cell lineages, and the widespread expression of this gene points to a fundamental cellular function, rather than one restricted to hematopoietic cells as previously suggested.
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PMID:The murine c-rel proto-oncogene encodes two mRNAs the expression of which is modulated by lymphoid stimuli. 220 17

Chromosomal aberrations occur in both B-CLL and T-CLL. The polyclonal B-cell mitogens, in particular Epstein-Barr virus and lipopolysaccharide from E. coli, have been used successfully to reveal chromosomal abnormalities in 40-60% of patients with B-CLL, while T-cell mitogens have shown chromosomal aberrations in T-CLL. The most common clonal chromosomal aberration in B-CLL is an extra chromosome 12, alone or together with other abnormalities. Other common aberrations are 14q+, structural aberrations on 6, 11, 12 and 13. Proto-oncogenes are frequently located close to breakpoints. The proto-oncogene c-K-ras is located on chromosome 12 and an abnormal transcript has recently been implicated in a subset of B-CLL-patients. An extra chromosome 12 as well as multiple chromosomal abnormalities in B-CLL appear to predict a less favourable prognosis. T-CLL is in most patients characterized by an inv(14), an extra 8q and structural abnormalities in chromosome 7. The genes for the specific T-cell receptor as well as the immunoglobulin heavy chain are located on these chromosomes. Chromosomal aberrations appear to have pathogenetic importance in both B-CLL and T-CLL.
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PMID:Role of chromosomal abnormalities in chronic lymphocytic leukemia. 333 2

In the course of studies of cell-mediated immunity in Graves' disease, we noted that normal peripheral blood monocytes, when stimulated by bacterial lipopolysaccharide, conditioned their media with a factor that had the physicochemical properties of the lymphokine interleukin-1 (IL-1) and that enhanced DNA synthesis and replication in quiescent FRTL5 cells, a line of nontransformed rat thyroid follicular cells. This finding led to the present studies, in which the effect of IL-1 (recombinant IL-1-p) on DNA synthesis in FRTL5 was explored. In the absence of serum, IL-1 induced a small, but significant, increase in [3H]thymidine incorporation into DNA. Calf serum (0.5%) alone also stimulated DNA synthesis slightly, but it greatly enhanced, in a synergistic manner, the stimulatory response to IL-1, decreasing the minimally effective concentration of IL-1 and amplifying the response to higher concentrations. A similar synergism was noted when quiescent FRTL5 were cultured with a combination of IL-1 and a low concentration of insulin-like growth factor-I (IGF-I), which itself stimulated DNA synthesis modestly. IL-1 also increased levels of the mRNA of the proto-oncogene c-myc in quiescent FRTL5, as TSH does, an effect thought to reflect commitment of the cell to increased growth. The findings indicate that IL-1 is an independent stimulator of thyroid cell growth, and that its effects are greatly enhanced by serum, probably in large measure by the IGF-I contained therein. They raise the possibility that IL-1 generated locally by intrathyroid macrophages may act directly by a short-loop mechanism to increase goiter formation in autoimmune thyroid disease.
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PMID:Interleukin-1 stimulates thyroid cell growth and increases the concentration of the c-myc proto-oncogene mRNA in thyroid follicular cells in culture. 349 69

Treatment of murine peritoneal macrophages for 30 min with lipopolysaccharide (LPS) resulted in a transient increase in c-fos proto-oncogene mRNA levels (Introna et al., 1986). After 2 h from the initial treatment, c-fos mRNA could no longer be detected and its expression could not be restimulated either by LPS or by other signals including colony stimulating factor-1 (CSF-1) and phorbol myristate acetate (PMA), both of which are able to induce expression of the c-fos gene in unstimulated macrophages. When LPS was removed after an initial 30 min incubation, responsiveness to a second exposure to LPS began to reappear after 3 h and was completely restored by 20 h. The same pattern of desensitization of c-fos induction was observed when CSF-1 stimulated macrophages were subsequently exposed to LPS. The loss of sensitivity to PMA following pretreatment with LPS was selective for c-fos expression as LPS treated macrophages remained responsive to PMA with respect to the ability to stimulate secretion of H2O2. The mechanism of desensitization was localized, at least in part, at the level of transcription as demonstrated by analysis of c-fos transcripts in nuclei isolated from macrophages pretreated and restimulated with LPS.
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PMID:Homologous and heterologous desensitization of proto-oncogene cfos expression in murine peritoneal macrophages. 357 35

Macrophages (M phi)3 function by a two-step process that includes priming (induction of cytokine and enzyme mRNA) and activation (production of effector molecules). The initial steps in M phi priming involve the expression of certain proto-oncogenes that regulate expression of other genes. Because tumor growth primes M phi to produce several suppressor monokines, we determined if cancer induced M phi expression of these proto-oncogenes. Unstimulated peritoneal M phi from tumor-bearing hosts (TBH) constitutively expressed the proto-oncogenes c-fms, c-fos, c-myc, and c-myb, whereas normal host (NH) M phi had little or no expression of these proto-oncogenes. When M phi were given a 24-h adherence priming stimulus, NH M phi expressed c-fms and c-fos at levels equivalent to TBH M phi constitutive expression. Adherence had little or no effect on c-fms and c-fos expression in TBH M phi or on NH and TBH M phi c-myc expression. c-myb expression was not induced in NH M phi during adherence and was strongly decreased in TBH M phi. Activation with a 1-h lipopolysaccharide-treatment increased NH and TBH M phi expression of c-fms, c-fos, and c-myc, with higher expression of these proto-oncogenes in TBH M phi. Activation failed to induce c-myb expression in NH M phi and completely inhibited expression in TBH M phi. Because c-fms, c-fos, and c-myc are normally expressed early during M phi activation, our results suggest that tumor growth primes M phi by inducing expression of these proto-oncogenes. c-myb is expressed in immature M phi and is downregulated during M phi activation. These observations explain why NH M phi expression of c-myb was not induced and are consistent with reports that suggest TBH M phi have not reached full developmental maturity. The induction of M phi proto-oncogene expression during cancer may put M phi in a primed state, which leads to earlier and stronger production of adverse suppressor and cytotoxic molecules.
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PMID:Macrophage priming and activation during fibrosarcoma growth: expression of c-myb, c-myc, c-fos, and c-fms. 785 63

The proto-oncogene c-abl encodes a tyrosine kinase that is hypothesized to function in proliferation-stimulatory signaling pathways. Previous work on mice homozygous for targeted mutations in the c-abl gene (ablml and abl2 mutant strains) has demonstrated multiple defects, including a susceptibility to infections that results in a high mortality rate after weaning. FACS analysis of the hemopoietic system of c-abl mutants demonstrated variable reductions in B and T lymphocytes in adult bone marrow, thymus, spleen, and peripheral blood. In addition, bone marrow from mutants showed a decreased ability to respond to interleukin-7. We further found that B cells from ablm1 mice had a reduced ability to respond to lipopolysaccharide (decreased to 10% of control response) that was dependent on the culture conditions and the tissue of origin of B cells. Peripheral blood from the mutants also had a reduced response to the T cell mitogen concanavalin A. Immune response in ablm1 mice as determined by the mixed lymphocyte response and the sheep red blood cell plaque-forming assay was grossly normal. These findings suggest that although specific signaling pathways in lymphocytes may involve c-Abl, the immune system can function in the absence of a normal c-abl gene product.
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PMID:Abnormal peripheral lymphocyte function in c-abl mutant mice. 880 12

The c-abl proto-oncogene is expressed ubiquitously during development. There are two predominant isoforms, type I and type IV. Their biological functions in cell growth and development are unknown. To examine their respective biological roles, we transduced 70Z/3 lymphoid cells with antisense sequences specific to each respective isotype. When the cells were incubated with antisense oligonucleotides against type IV c-abl but not against type I c-abl, induction of apoptosis was observed, as measured by either DNA fragmentation, cell proliferation, or colony formation. Immunoprecipitation showed that antisense-treated cells had reduced amounts of c-abl as compared to the untreated cells. When stimulated with lipopolysaccharide (LPS), 70Z/3 cells underwent proliferation and differentiation. When antisense oligonucleotides against type IV were added to the cell cultures, with LPS stimulation, induction of apoptosis continued to occur. When antisense oligonucleotides against type I were added in the cultures, in the presence of LPS, cell differentiation was inhibited, but cell proliferation continued to occur. This inhibition of differentiation was evident by a lack of immunoglobulin light chain production by cells that otherwise would produce immunoglobulin when they are stimulated with LPS. These data therefore show that type I c-abl allows cell differentiation to occur, whereas type IV c-abl suppresses apoptosis.
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PMID:Isoform-specific functions of c-abl: type I is necessary for differentiation, and type IV is inhibitory to apoptosis. 887 95

Although adult murine B cells can be stimulated to proliferate by Igm receptor cross-linking, we and others have shown that these cells will undergo apoptosis in vitro in a dose-, time- and temperature-dependent manner with polyclonal but not monoclonal anti-IgM, To test the role of c-myc and cell cycle progression in B cell apoptosis, we examined normal, Sp6 anti-TNP lg and E micro-myc transgenic splenocytes for receptor-mediated apoptosis in vitro. In normal mice, both spontaneous and anti-IgM-induced programmed cell death were specifically blocked by antisense oligodeoxynucleotides for the c-myc proto-oncogene, whereas nonsense myc oligonucleotides and irrelevant oligonucleotides had only a minor effect. Similarly, TNP-dextran-induced apoptosis in Sp6 anti-TNF transgenics was inhibited by antisense c-myc. This effect was not due to the mitogenic effects of unmethylated CpG-containing sequences because ones lacking this motif, as well as methylated oligonucleotides containing this motif, prevented apoptosis, and mitogenic doses of lipopolysaccharide failed to inhibit anti-IgM-driven cell death. Importantly, antisense c-myc also prevented the anti-IgM-induced increase in myc protein species. Moreover, spontaneous apoptosis in vitro was exaggerated in E micro-myc transgenic B cells. To examine the role of CD45 in anti-IgM-induced apoptosis, we treated spleen cells from CD45 knockout mice, which do not proliferate with anti-IgM, and found that B cells from these underwent apoptosis normally despite the lack of entry into S. These data suggest that anti-IgM driven apoptosis does not require CD45. Rather, apoptosis may be due to an overexpression of myc protein in the absence of signals which can drive B cells productively into S, but the failure to proliferate normally is insufficient for apoptosis to occur.
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PMID:Role of c-myc and CD45 in spontaneous and anti-receptor-induced apoptosis in adult murine B cells. 892 15


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