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)

We have examined the role of tyrosine phosphorylation during the course of macrophage activation. Initial experiments indicated that vanadate, a known phosphotyrosine phosphatase inhibitor, enhanced the phorbol 12-myristate 13-acetate (PMA)-triggered respiratory burst and potentiated the priming effects of bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma), suggesting that tyrosine phosphorylation may be important in these end cell functions. As src-related kinases have been implicated in the activation of cells of other haemopoietic lineages, we examined the relationship between the activity of two such kinases, hck and lyn, and priming of the respiratory burst. We found that the level of hck and lyn is increased following exposure of bone marrow-derived macrophages (BMM) to LPS or IFN-gamma. The induction of both of these kinases follows similar kinetics with maximal activity occurring at 24-48 h. Interestingly, the kinetics of induction of hck and lyn kinase activity in BMM demonstrated a close temporal relationship with the priming effects of LPS and IFN-gamma on the macrophage respiratory burst. Collectively, these observations raise the possibility that modulation of expression of hck and lyn is involved in the regulation of the respiratory burst.
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PMID:Lipopolysaccharide- and interferon-gamma-induced expression of hck and lyn tyrosine kinases in murine bone marrow-derived macrophages. 137 83

The structure and function of the promoter region and exon 1 of the murine hck gene have been characterized in detail. RNase protection analysis has established that hck transcripts initiate from heterogeneous start sites located within the hck gene. Fusion gene constructs containing hck 5'-flanking sequences and the bacterial Neor gene have been introduced into the hematopoietic cell lines FDC-P1 and WEHI-265 by using a self-inactivating retroviral vector. The transcriptional start sites of the fusion gene are essentially identical to those of the endogenous hck gene. Analysis of infected WEHI-265 cell lines treated with bacterial lipopolysaccharide (LPS) reveals a 3- to 5-fold elevation in the levels of endogenous hck mRNA and a 1.4- to 2.6-fold increase in the level of Neor fusion gene transcripts, indicating that hck 5'-flanking sequences are capable of conferring LPS responsiveness on the Neor gene. The 5'-flanking region of the hck gene contains sequences similar to an element which is thought to be involved in the LPS responsiveness of the class II major histocompatibility gene A alpha k. A subset of these sequences are also found in the 5'-flanking regions of other LPS-responsive genes. Moreover, this motif is related to the consensus binding sequence of NF-kappa B, a transcription factor which is known to be regulated by LPS.
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PMID:Functional analysis and nucleotide sequence of the promoter region of the murine hck gene. 238 19

We and others have previously reported that tyrosine kinases play key roles in the activation of macrophages by both bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). However, little is known regarding the substrates of tyrosine phosphorylation that mediate macrophage activation and the resultant production of inflammatory mediators. In lymphocytes and other hematopoietic lineages, tyrosine phosphorylation of the proto-oncogene vav appears to be an essential component of cell activation. In this study, we demonstrate that both LPS and rIFN-gamma trigger the prompt, dose-dependent tyrosine phosphorylation of vav in murine RAW 264.7 macrophages. In addition, vav is physically associated with the src-related kinase hck in murine macrophages, and antisense oligonucleotides specific for murine hck block both LPS and rIFN-gamma-mediated vav phosphorylation. These findings suggest that hck probably mediates vav tyrosine phosphorylation during macrophage activation and that LPS and rIFN-gamma-mediated signaling pathways partially overlap.
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PMID:Bacterial LPS and IFN-gamma trigger the tyrosine phosphorylation of vav in macrophages: evidence for involvement of the hck tyrosine kinase. 940 Aug 28

Signal transduction through the leukocyte integrins is required for the processes of firm adhesion, activation, and chemotaxis of neutrophils during inflammatory reactions. Neutrophils isolated from knockout mice that are deficient in the expression of p59/61(hck) (Hck) and p58(c-fgr) (Fgr), members of the Src-family of protein tyrosine kinases, have been shown to be defective in adhesion mediated activation. Cells from these animals have impaired induction of respiratory burst and granule secretion following plating on surfaces that crosslink beta2 and beta3 integrins. To determine if the defective function of hck-/-fgr-/- neutrophils observed in vitro also results in impaired inflammatory responses in vivo, we examined responses induced by lipopolysaccharide (LPS) injection in these animals. The hck-/-fgr-/- mice showed marked resistance to the lethal effects of high-dose LPS injection despite the fact that high levels of serum tumor necrosis factor alpha and interleukin 1alpha were detected. Serum chemistry analysis revealed a marked reduction in liver and renal damage in mutant mice treated with LPS, whereas blood counts showed a marked neutrophilia that was not seen in wild-type animals. Direct examination of liver sections from mutant mice revealed reduced neutrophil migration into the tissue. These data demonstrate that defective integrin signaling in neutrophils, caused by loss of Hck and Fgr tyrosine kinase activity, results in impaired inflammation-dependent tissue injury in vivo.
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PMID:Resistance to endotoxic shock and reduced neutrophil migration in mice deficient for the Src-family kinases Hck and Fgr. 963 92

Tyrosine phosphorylation pathways are essential components of the process of macrophage activation and the resultant production of inflammatory mediators such as tumor necrosis factor (TNF) and nitric oxide (NO). Several lines of evidence suggest that members of the src family of protein tyrosine kinases play important roles in macrophage activation by gram-negative bacterial lipopolysaccharide (LPS) or the cytokine interferon-gamma (IFN-gamma), but targeted disruption of three members of the src family (hck, fgr, and lyn) in mice failed to demonstrate a requirement for these particular kinases in macrophage activation. We report that the pyrazolopyrimidine PP1, a src family-selective tyrosine kinase inhibitor, potently inhibits the production of TNF and inducible nitric oxide synthase (iNOS) in RAW 264.7 murine macrophages stimulated with LPS, rlFN-gamma, or LPS + rIFN-gamma. Furthermore, the tested concentrations of PP1 inhibit LPS- and rlFN-gamma-mediated tyrosine phosphorylation of the hck tyrosine kinase and its putative substrate, vav, but fail to block rlFN-gamma-mediated JAK2 tyrosine phosphorylation. These findings provide additional support for a model of macrophage activation involving one or more src-related kinases. Selective inhibitors of this signaling pathway should be studied in animal models of sepsis.
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PMID:The src family-selective tyrosine kinase inhibitor PP1 blocks LPS and IFN-gamma-mediated TNF and iNOS production in murine macrophages. 1056 9

In macrophages, bacterial lipopolysaccharide (LPS) has been noted to mimic certain effects of the sphingolipid ceramide, suggesting that ceramide may be involved in macrophage activation by LPS and/or that LPS utilizes ceramide-related signaling pathways. Putative downstream targets of ceramide include a ceramide-activated (serine/threonine) protein kinase (CAPK) and phosphatase (CAPP). However, the potential role of tyrosine phosphorylation pathways in macrophage response to ceramide has not been examined. Herein we report that cell-permeable analogs of ceramide up-regulate both inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF) production in RAW 264.7 murine macrophages. Herbimycin A and genistein, potent natural inhibitors of protein tyrosine (but not serine/threonine) phosphorylation, block ceramide-induced iNOS and TNF production. Furthermore, the highly src-family selective pyrazolopyrimidine inhibitor PP1 also blocks ceramide-induced iNOS and TNF production in RAW 264.7 cells. We found that PP1 also inhibits ceramide-mediated tyrosine phosphorylation of the src-family kinase hck. These data indicate that src-related tyrosine kinases play a critical role in macrophage activation by ceramide.
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PMID:Ceramide-mediated stimulation of inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF) accumulation in murine macrophages requires tyrosine kinase activity. 1081 Oct 15

Protein tyrosine kinase (PTK) activity is abundant in microglia, but the PTKs that participate in their activation have not been identified. For these studies, we used three paradigms to characterize PTK expression during microglial activation: resting and activated microglia were bulk fractionated from the adult brain, cultured newborn microglia were treated with lipopolysaccharide (LPS) to model the transition from activated toward phagocytic microglia, and PTK expression was examined in activated microglia in situ after facial nerve axotomy. Two PCR-based strategies were used to show that 21 different PTK genes are expressed by rat brain microglia: 5 receptor PTKs, 10 nonreceptor PTKs, and 6 members of the src family. Seven of the 21 PTKs were examined in greater detail. Five PTK mRNAs (fgr, hck, fak, jak-2, and flk-1) increased expression across all three models of activation. We conclude that they represent key components in the cascades that participate in microglial activation. In contrast, expression of fes and fms correlated with stimuli that affect microglial proliferation. Four of the PTKs (hck, fgr, fes, and fms) are believed to be myeloid cell specific and were not expressed by cultured astrocytes. HCK and FAK protein were also not expressed in lysates of immature astrocytes and oligodendrocytes. Because of their putative specificity, these kinases represent potential targets for inhibitors of microglial activation. Because reactive microglia can exacerbate the severity of neurological diseases, the identification of specific kinases that participate in microglial activation represents an important advance toward the development of new therapeutics.
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PMID:Differential expression of protein tyrosine kinase genes during microglial activation. 1223 40

vav1 has been shown to play a key role in lymphocyte development and activation, but its potential importance in macrophage activation has received little attention. We have previously reported that exposure of macrophages to bacterial lipopolysaccharide (LPS) leads to increased activity of hck and other src-related tyrosine kinases and to the prompt phosphorylation of vav1 on tyrosine. In this study, we tested the role of vav1 in macrophage responses to LPS, focusing on the upregulation of nuclear factor for interleukin-6 expression (NF-IL-6) activity and inducible nitric oxide synthase (iNOS) protein accumulation in RAW-TT10 murine macrophages. We established a series of stable cell lines expressing three mutant forms of vav1 in a tetracycline-regulatable fashion: (i) a form producing a truncated protein, vavC; (ii) a form containing a point mutation in the regulatory tyrosine residue, vavYF174; and (iii) a form with an in-frame deletion of 6 amino acids required for the guanidine nucleotide exchange factor (GEF) activity of vav1 for rac family GTPases, vavGEFmt. Expression of the truncated mutant (but not the other two mutants) has been reported to interfere with T-cell activation. In contrast, we now demonstrate that expression of any of the three mutant forms of vav1 in RAW-TT10 cells consistently inhibited LPS-mediated increases in iNOS protein accumulation and NF-IL-6 activity. These data provide direct evidence for a role for vav1 in LPS-mediated macrophage activation and iNOS production and suggest that vav1 functions in part via activation of NF-IL-6. Furthermore, these findings indicate that the GEF activity of vav1 is required for its ability to mediate macrophage activation by LPS.
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PMID:Role of vav1 in the lipopolysaccharide-mediated upregulation of inducible nitric oxide synthase production and nuclear factor for interleukin-6 expression activity in murine macrophages. 1513 77

As tyrosine kinases are indispensable in lipopolysaccharide (LPS)-induced macrophage activation, the myeloid-specific Src members (i.e. Lyn, Fgr and Hck) are speculated to play important roles in this process. However, the normal LPS responsiveness in lyn(-/-)fgr(-/-)hck(-/-) macrophages implicates the presence of an elusive, compensating tyrosine kinase(s). In this study, we demonstrate the upregulation of c-Src in Raw264.7 and peritoneal macrophages (PEMs) by LPS, which is inhibited by PP2 (an inhibitor for Src family kinases), pyrrolidinedithiocarbamate (PDTC; NF-kappaB inhibitor) and LY294002 (PI3K inhibitor). And this LPS-mediated c-Src induction is also observed in macrophages recovered from LPS-challenged rats. Intriguingly, PP2 attenuates the ability of PEMs to elicit COX-2 expression and nitric oxide production in response to LPS. Similar results are also observed when macrophages recovered from rats receiving either LPS alone or LPS and PP2 both are compared. Furthermore, administration of PP2 in Raw264.7 and animal models of sepsis greatly suppresses TNFalpha secretion and serum TNFalpha level, respectively. Therefore, we conclude that c-Src, with its LPS induction, has an unperceived role in transmitting LPS signaling in macrophages.
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PMID:Lipopolysaccharide-induced c-Src expression plays a role in nitric oxide and TNFalpha secretion in macrophages. 1586 94