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)

In the present article we show that supernatants derived from lipopolysaccharide (LPS) or phorbol 12-myristate 13-acetate (PMA)-stimulated A-20 B cell lymphoma are able to induce polyclonal immunoglobulin (Ig) secretion by normal B cells in a T-cell-dependent manner. This activity could be blocked by neutralizing monoclonal antibodies against interferon-gamma, but not by monoclonal antibodies against interleukin (IL)-2, IL-4, IL-5, IL-6, IL-10 and granulocyte macrophage colony-stimulating factor (GM-CSF) or even a polyclonal antibody against tumor necrosis factor (TNF)-alpha. Furthermore, A-20 supernatants induced the production of measurable amounts of interferon-gamma by normal murine spleen cells and activates natural killer (NK) cells. Fractionation of factor-rich supernatants on a Sephacryl S-200 column revealed that the factor activity is located in the fractions corresponding to a molecular mass of 160-150 kDa and 80-70 kDa. The biological activities found in the A-20 supernatant are very similar to the ones described for the recently cloned human IL-12/NK cell stimulatory factor. These results suggest the existence of a murine analogous factor for the human IL-12 produced by A-20 B cell lymphoma.
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PMID:An activated murine B cell lymphoma line (A-20) produces a factor-like activity which is functionally related to human natural killer cell stimulatory factor. 135 72

B29 is a B-lineage-specific gene predicted from sequence information to be a transmembrane member of the immunoglobulin (Ig) superfamily, with a single extracellular Ig-like domain. Its presumptive cytoplasmic region contains a peptide motif present in CD3 and other molecules involved in lymphocyte activation. Affinity-purified goat antibodies were prepared to a TrpE fusion protein of B29 and used to study B29 expression on lymphoid cells. The antiserum precipitated surface-labeled heterodimers from B lymphoma cells. One was 65-88 kDa (unreduced) or 36-47 plus 32-34 kDa (reduced) by SDS/PAGE analysis, regardless of detergent. A smaller heterodimer was detected only with Triton detergent extraction. IgM molecules were coprecipitated by the B29 antiserum when the weak detergent digitonin was used. In addition, cocapping experiments revealed that most B29 molecules codistribute with Ig on the cell surface. Although early B-lineage cells and plasma cells contain B29 mRNA, surface expression was detectable only on B cells that had significant amounts of surface Ig. The surface expression was B-lineage-specific and included cells from mutant xid mice and B-cell lines representing mu, delta, gamma, and alpha heavy-chain isotypes and both kappa and lambda light-chain types. The density of surface B29 protein correlated directly with surface mu heavy-chain density on subclones of a B-cell lymphoma and lipopolysaccharide-stimulated pre-B cells. These findings show that B29 is covalently linked in a heterodimer and are consistent with a recently proposed model of surface Ig complexes.
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PMID:B29 gene products complex with immunoglobulins on B lymphocytes. 173 34

Treatment of splenic B lymphocytes and certain B-lineage cell lines with the mitogen lipopolysaccharide (LPS) and the lymphokine interleukin-4 (IL-4) induces expression of germ line immunoglobulin C epsilon transcripts and class switching to the C epsilon gene. We show that LPS-plus-IL-4 induction of germ line epsilon transcripts (termed I epsilon transcripts) occurs at the transcriptional level in an Abelson murine leukemia virus-transformed pre-B-cell line. A 1.1-kb region of DNA surrounding the I epsilon promoter endows inducible transcription to a heterologous reporter gene stably transfected into these cells; such inducible expression depends on combined treatment with LPS and IL-4. Analyses of constructs transiently introduced into a B-cell lymphoma line demonstrated that LPS-plus-IL-4-inducible expression can be conferred by a 179-bp segment of DNA spanning the I epsilon transcriptional initiation site. Mutational analyses demonstrated that this expression depended on DNA sequences within a conserved region directly upstream from the I epsilon transcriptional initiation region. One nuclear protein that is constitutively expressed in normal B cells binds to the downstream end of the conserved sequence; its binding specificity correlates with the functional effect of several mutations. Two additional proteins, which are induced by IL-4 treatment of splenic B cells, bind to the transcription initiation sites of I epsilon. These proteins are indistinguishable in binding assays from proteins previously shown to bind an enhancer region of the class II major histocompatibility complex gene A alpha.
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PMID:Identification of a conserved lipopolysaccharide-plus-interleukin-4-responsive element located at the promoter of germ line epsilon transcripts. 192 63

The mouse B cell lymphoma 70Z/3 is membrane immunoglobulin M (mIgM) negative, but treatment of the cells with bacterial lipopolysaccharide (LPS) induces the expression of kappa (kappa) light chain synthesis, and the cells become mIgM+. In wild type cells, this reaction is maximal after 24 h; we have isolated a variant, 1B8, which becomes mIgM+ only after a more prolonged incubation with LPS. This delayed response results from a reduced rate of accumulation of (kappa) mRNA and protein. The transcription factor, NF-kappa B is present in the cytoplasm of both the wild type and the variant cells in its inactive form. The delay in kappa expression is correlated with the failure of NF-kappa B to be activated and translocated to the nucleus. Although NF-kappa B cannot be activated by LPS, it can be activated by treatment with phorbol ester (PMA). In contrast to the clear defect in NF-kappa B, LPS treatment of 1B8 cells causes the octamer-binding factor OTF-2 to increase normally. We conclude that the defect in 1B8 cells is in an early part of the LPS activation pathway, prior to the activation of NF-kappa B, but after the signal for OTF-2 induction. The phenotype of 1B8 demonstrates that an increase in OTF-2 alone is sufficient to cause a large increase in kappa transcription in 70Z/3 cells, but that without NF-kappa B, the response is slow to develop. In this view, NF-kappa B functions to facilitate kappa transcription and to speed its rate of increase, but is not required for the long-term response of 70Z/3 cells to LPS.
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PMID:Slow response variant of the B lymphoma 70Z/3 defective in LPS activation of NF-kappa B. 210 8

Murine Ly1+ pre-B cell lines, including 70Z/3 and three pre-B cell lines derived from long-term bone marrow cultures, exhibited selective adherence to bone marrow stromal cells. In contrast, splenic B cells, the A20 B-cell lymphoma, and four Ly1- B cell lines derived from long-term bone marrow cultures failed to adhere substiantially to bone marrow cultures failed to adhere substiantially to bone marrow stroma. Ly1+ pre-B cell lines were induced to express kappa light chains by exposure to either lipopolysaccharide (LPS), recombinant interleukin-1 (IL-1), or stromal cells. However, induction of kappa light chains failed to prevent pre-B cell adherence to stromal cells. Supernatants derived from primary bone marrow stromal cells decreased Ly1 expression on the Ly1+ pre-B cell lines. These experiments suggest that (1) expression of immunoglobulin light chains by developing Ly1+ pre-B cells is mediated by bone marrow stromal cells; (2) loss of specific adherence to stroma is progressive and occurs post-light chain induction; and (3) soluble products of stromal cells may downregulate expression of surface Ly1 on otherwise Ly1+ pre-B cells. The importance of these observations to the development of both the Ly1- and Ly1+ B cell lineages in the mouse is discussed.
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PMID:Bone marrow stromal cells modulate both kappa light chain and Ly1 antigen expression on Ly1+ pre-B cell lines in vitro. 211 35

The inducible B cell lymphoma, CH12, and its in vitro adapted subclone, CH12-LBK, produce immunoglobulins of identical sequence, specificity and isotype, with equivalent affinities for the hapten trimethyl ammonium. However, the hemolytic efficiencies of the antibody secreted by the two cell lines are quite different. Antibody preparations from lipopolysaccharide-stimulated CH12 cells lyse erythrocytes six- to ten times more effectively than antibody preparations of the same concentration from CH12-LBK cells. Both cell lines secrete polymeric IgM, but while CH12-LBK cells secrete predominantly the canonical pentameric IgM, CH12 cells secrete a mixture of pentamers and hexamers. High-efficiency complement-dependent cytolysis is associated with hexameric IgM, which has a specific activity that is approximately twenty times higher than that of the pentameric form. J chain protein is found in the secreted IgM of both cell lines, but is associated only with the pentameric IgM and not with the hexameric form, nor with any intermediate polymers smaller than a pentamer. A deficit in, or the inaccessibility of, J chain protein appears to facilitate hexamer formation. These experiments confirm previously published data showing that J chain is not necessary either for assembly or secretion of polymeric IgM, and suggest instead that J chain may be important in regulating the lytic efficiency of polymeric IgM by controlling the IgM pentamer/hexamer ratio. The experiments further suggest a mechanism, in addition to isotype switching and somatic mutation, by which the biological efficiency of antibodies from a single clone of B cells can be regulated.
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PMID:The biological effects of IgM hexamer formation. 212 70

We describe the structure of the major germ line RNA transcribed from unrearranged immunoglobulin alpha heavy-chain genes in immunoglobulin M-expressing cells of the I.29 mu B-cell lymphoma, a cell line capable of switching to immunoglobulin A expression upon lipopolysaccharide treatment. This germ line alpha RNA has a small open reading frame that does not include the C alpha domain, and this RNA appears to be present on polysomes in I.29 mu cells.
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PMID:Structure of germ line immunoglobulin alpha heavy-chain RNA and its location on polysomes. 215 64

Endogenous mouse mammary tumor virus (MMTV) proviral transcripts are up regulated during the normal course of B-lymphocyte differentiation. We report here that the regulatory mechanisms which lead to increased levels of MMTV transcripts in differentiating, lipopolysaccharide (LPS)-stimulated normal B cells and in the inducible B-cell lymphoma line CH12 are at least partially distinct from those controlling increases in immunoglobulin and J-chain gene expression. In studies designed to characterize the stimulatory pathways leading to MMTV expression in CH12 cells, we found that stimulation with either LPS or dexamethasone (Dex), a transcriptional activator of MMTV genes, induced not only MMTV expression but also differentiation to antibody secretion. Only Dex-induced and not LPS-induced MMTV expression and differentiation were inhibited by the glucocorticoid antagonist RU486, demonstrating that Dex and LPS stimulate B cells by distinct molecular pathways. Therefore, in B cells, MMTV expression can be regulated via either the conventional hormone receptor-dependent pathway or a hormone receptor-independent pathway. Furthermore, these results suggest that steroid stimulation of B cells can lead to alterations in the expression of other results suggest that steroid stimulation of B cells can lead to alterations in the expression of other steroid-responsive genes that can become involved in the process of B-cell differentiation.
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PMID:Lipopolysaccharide and dexamethasone induce mouse mammary tumor proviral gene expression and differentiation in B lymphocytes through distinct regulatory pathways. 216 35

The murine B-cell lymphoma CH12, like many other murine cells, expresses intracisternal A-type particles (IAPs). When CH12 cells are treated with lipopolysaccharide, the cells differentiate and secrete immunoglobulin M. The expression of IAP genes was also increased, in parallel with the increased expression of immunoglobulin genes. The amount of IAP mRNA increased within 48 h of lipopolysaccharide treatment and reached a level fivefold higher than that in unactivated CH12 cells. The two major IAP transcripts (7.2 and 5.4 kilobases) were induced to similar extents. The increased level of mRNA was reflected in higher levels of the major IAP structural protein p70, whose abundance increased 3.6-fold. The number of IAP particles per cell also increased upon activation of CH12, from 67 in nonsecreting CH12 to 290 in secreting cells. All of the IAPs were confined to the cisternae of the endoplasmic reticulum (ER), regardless of the differentiation state of the cell. Accompanying the induction of p70 was the induction of the related IAP polypeptide p102. A third viral polypeptide, p120, was also made in CH12; its abundance was almost unchanged. Localization of the IAP proteins on ultrathin frozen sections showed that most were assembled into particles in the ER. However, there were small pools of unassembled proteins both in the ER and on the plasma membrane. p70 and p120 could be detected, by iodination, on the surfaces of both secreting and nonsecreting CH12 cells. Unlike p70 and p120, p102 did not seem to be membrane associated. Taken together, these observations show that IAP expression is regulated developmentally in B lymphocytes. Also, these observations point to possible interactions between IAP genes and other cellular genes.
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PMID:Expression of intracisternal A-type particles is increased when a B-cell lymphoma differentiates into an immunoglobulin-secreting cell. 249 59

The B cell lymphoma line WEHI 279.1 (surface IgM+, I-A+ and I-E+) was used as a model system to analyze functional reactivity of B lymphocytes to mitogens. Among the mitogens tested, lipopolysaccharide (LPS), lipoprotein (LP), and dextran sulfate (DxS) all induced a strong, dose-dependent growth inhibition of tumor cells. The analysis of independently derived clones, however, revealed that mitogen sensitivity could be lost in the absence of detectable alterations in the expression of those surface markers. Moreover, reactivity to LPS, LP and DxS segregated independently in these clones, suggesting distinct triggering mechanisms and functional receptors for these mitogens on the B cell membrane.
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PMID:Segregation of reactivity to the mitogens lipopolysaccharide, lipoprotein and dextran sulfate in clones of the B cell lymphoma line WEHI 279.1. 257 67


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