UNIPROT:P51812 - FACTA Search

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Query: UNIPROT:P51812 (mitogen-activated protein)
10,636 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proinflammatory mediators such as cytokines and NO play pivotal roles in various inflammatory diseases. To combat inflammatory diseases successfully, regulation of proinflammatory mediator production would be a critical process. In the present study, we investigated the in vitro effects of ethyl (6R)-6-[N-(2-chloro-4-fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate (TAK-242), a novel small molecule cytokine production inhibitor, and its mechanism of action. In RAW264.7 cells and mouse peritoneal macrophages, TAK-242 suppressed lipopolysaccharide (LPS)-induced production of NO, tumor necrosis factor-alpha (TNF-alpha), and interleukin (IL)-6, with 50% inhibitory concentration (IC50) of 1.1 to 11 nM. TAK-242 also suppressed the production of these cytokines from LPS-stimulated human peripheral blood mononuclear cells (PBMCs) at IC50 values from 11 to 33 nM. In addition, the inhibitory effects on the LPS-induced IL-6 and IL-12 production were similar in human PBMCs, monocytes, and macrophages. TAK-242 inhibited mRNA expression of IL-6 and TNF-alpha induced by LPS and interferon-gamma in RAW264.7 cells. The phosphorylation of mitogen-activated protein kinases induced by LPS was also inhibited in a concentration-dependent manner. However, TAK-242 did not antagonize the binding of LPS to the cells. It is noteworthy that TAK-242 suppressed the cytokine production induced by Toll-like receptor (TLR) 4 ligands, but not by ligands for TLR2, -3, and -9. In addition, IL-1beta-induced IL-8 production from human PBMCs was not markedly affected by TAK-242. These data suggest that TAK-242 suppresses the production of multiple cytokines by selectively inhibiting TLR4 intracellular signaling. Finally, TAK-242 is a novel small molecule TLR4 signaling inhibitor and could be a promising therapeutic agent for inflammatory diseases, whose pathogenesis involves TLR4.
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PMID:A novel cyclohexene derivative, ethyl (6R)-6-[N-(2-Chloro-4-fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate (TAK-242), selectively inhibits toll-like receptor 4-mediated cytokine production through suppression of intracellular signaling. 1637 89

Although the 38-kDa glycolipoprotein of Mycobacterium tuberculosis H37Rv is known to evoke prominent cellular and humoral immune responses in human tuberculosis (TB), little information is known about intracellular regulatory mechanisms involved in 38-kDa antigen (Ag)-induced host responses. In this study, we found that purified 38-kDa glycolipoprotein activates mitogen-activated protein kinases (MAPKs; extracellular signal-regulated kinase 1/2 [ERK1/2] and p38) and induces tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) in human monocytes. When the 38-kDa Ag was applied to monocytes from TB patients and healthy controls, the activation of ERK1/2 and p38 MAPK and the subsequent cytokine secretion were greater in the monocytes from the active pulmonary TB patients than in monocytes from the healthy controls. Additionally, neutralizing antibodies for Toll-like receptor 2 (TLR2) or TLR4 significantly reduced the ERK1/2 and p38 activation induced by the 38-kDa protein when the antibodies were applied to HEK293 cells overexpressing TLR2 or TLR4 as well as human primary monocytes. Furthermore, the inhibition of TLR2 significantly, and that of TLR4 partially, decreased the 38-kDa Ag-induced secretion of TNF-alpha and IL-6 in human monocytes. The intact protein moieties of the 38-kDa protein were responsible for biologic activities by this Ag. These data collectively demonstrate that the 38-kDa glycolipoprotein, acting through both TLR2 and TLR4, induces the activation of the ERK1/2 and p38 MAPK pathways, which in turn play an essential role in TNF-alpha and IL-6 expression during mycobacterial infection.
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PMID:The mycobacterial 38-kilodalton glycolipoprotein antigen activates the mitogen-activated protein kinase pathway and release of proinflammatory cytokines through Toll-like receptors 2 and 4 in human monocytes. 1662 5

The diacylated lipopeptide FSL-1 enhanced the generation of IgG antibodies in TLR2(+/+) mice, but not in TLR2(-/-) mice, when administered together with hen egg lysozyme as an antigen. Escherichia coli lipopolysaccharide enhanced the generation of antigen-specific antibodies in both TLR2(-/-) and TLR2(+/+) mice. In TLR2(+/+) mice, the level of enhancement due to FSL-1 was similar to that caused by lipopolysaccharide. Analysis of the IgG antibodies subclass demonstrated that the level of Th2-type IgG1 antibodies was higher than that of Th1-type IgG2a antibodies. Both FSL-1 and lipopolysaccharide induced production of IL-10 and IL-6 by splenocytes from TLR2(+/+) mice. Lipopolysaccharide also induced production of these cytokines by splenocytes from TLR2(-/-) mice, but FSL-1 did not. Neither FSL-1 nor lipopolysaccharide induced IL-12p70 production by splenocytes from either type of mice. FSL-1 upregulated B7.2 expression in B220(+) cells from TLR2(+/+) mice but not those from TLR2(-/-) mice, whereas lipopolysaccharide upregulated B7.2 expression in B220(+) cells from both types of mice. FSL-1 and, to a lesser extent, lipopolysaccharide activated mitogen-activated protein kinases in splenocytes. FSL-1 and, to a lesser extent, lipopolysaccharide induced the expression of c-Fos, which is known to be involved in Th2-type responses, in splenocytes. Thus, this study demonstrated that FSL-1 possessed TLR2-mediated Th2-type responses in vivo.
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PMID:The diacylated lipopeptide FSL-1 induces TLR2-mediated Th2 responses. 1696 51

Severe injury deranges immune function and increases the risk of sepsis and multiple organ failure. Kupffer cells play a major role in mediating posttraumatic immune responses, in part via different Toll-like receptors (TLR). Although mitogen-activated protein kinases (MAPK) are key elements in the TLR signaling pathway, it remains unclear whether the activation of different MAPK are TLR specific. Male C3H/HeN mice underwent midline laparotomy (i.e., soft tissue injury), hemorrhagic shock (MAP approximately 35 mm Hg for 90 min), and resuscitation. Kupffer cells were isolated 2 h thereafter, lysed and immunoblotted with antibodies to p38, ERK1/2, or JNK proteins. In addition, cells were preincubated with specific inhibitors of p38, ERK1/2, or JNK MAPK followed by stimulation with the TLR2 agonist, zymosan; the TLR4 agonist, LPS; or the TLR9 agonist, CpG DNA. Cytokine (TNF-alpha, interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and KC) production was determined by cytometric bead array after 24 h in culture. MAPK activity as well as TNF-alpha, MCP-1, and KC production by Kupffer cells were significantly increased following trauma-hemorrhage. TLR4 activation by LPS stimulation increased the levels of all measured cytokines. CpG-stimulated TLR9 signaling increased TNF-alpha and IL-6 levels; however, it had no effect on chemokine production. Selective MAPK inhibition demonstrated that chemokine production was mediated via p38 and JNK MAPK activation in TLR2, -4, and -9 signaling. In contrast, TNF-alpha and IL-6 production was differentially regulated by MAPK depending on the TLR pathway stimulated. Thus, Kupffer cell TLR signaling employs different MAPK pathways in eliciting cytokine and chemokine responses following trauma-hemorrhage.
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PMID:The role of MAPK in Kupffer cell toll-like receptor (TLR) 2-, TLR4-, and TLR9-mediated signaling following trauma-hemorrhage. 1711 77

Toll-like receptors (TLRs) recognize Mycobacterium tuberculosis (Mtb) or Mtb components and initiate mononuclear phagocyte responses that influence both innate and adaptive immunity. Recent studies have revealed the intracellular signalling cascades involved in the TLR-initiated immune response to mycobacterial infection. Although both TLR2 and TLR4 have been implicated in host interactions with Mtb, the relationship between specific mycobacterial molecules and various signal transduction pathways is not well understood. This review will discuss recent studies indicating critical roles for mycobacteria and mycobacterial components in regulation of mitogen-activated protein kinases and related signal transduction pathways that govern the outcome of infection and antibacterial defence. To better understand the roles of infection-induced signalling cascades in molecular pathogenesis, future studies are needed to clarify mechanisms that integrate the multiple signalling pathways that are activated by engagement of TLRs by both individual mycobacterial molecules and whole mycobacteria. These efforts will allow for the development of novel diagnostic and therapeutic modalities for tuberculosis that targets the intracellular signalling pathways permitting the replication of this nefarious pathogen.
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PMID:Intracellular signalling cascades regulating innate immune responses to Mycobacteria: branching out from Toll-like receptors. 1735 35

In this study, we examined whether tyrosine phosphorylation of the Toll-IL-1 resistance (TIR) domain of Toll-like receptor (TLR) 4 is required for signaling and blocked in endotoxin tolerance. Introduction of the P712H mutation, responsible for lipopolysaccharide (LPS) unresponsiveness of C3H/HeJ mice, into the TIR domain of constitutively active mouse DeltaTLR4 and mutation of the homologous P714 in human CD4-TLR4 rendered them signaling-incompetent and blocked TLR4 tyrosine phosphorylation. Mutations of tyrosine residues Y674A and Y680A within the TIR domains of CD4-TLR4 impaired its ability to elicit phosphorylation of p38 and JNK mitogen-activated protein kinases, IkappaB-alpha degradation, and activation of NF-kappaB and RANTES reporters. Likewise, full-length human TLR4 expressing Y674A or Y680A mutations showed suppressed capacities to mediate LPS-inducible cell activation. Signaling deficiencies of the Y674A and Y680A TLR4s correlated with altered MyD88-TLR4 interactions, increased associations with a short IRAK-1 isoform, and decreased amounts of activated IRAK-1 in complex with TLR4. Pretreatment of human embryonic kidney (HEK) 293/TLR4/MD-2 cells with protein tyrosine kinase or Src kinase inhibitors suppressed LPS-driven TLR4 tyrosine phosphorylation, p38 and NF-kappaB activation. TLR2 and TLR4 agonists induced TLR tyrosine phosphorylation in HEK293 cells overexpressing CD14, MD-2, and TLR4 or TLR2. Induction of endotoxin tolerance in HEK293/TLR4/MD-2 transfectants and in human monocytes markedly suppressed LPS-mediated TLR4 tyrosine phosphorylation and recruitment of Lyn kinase to TLR4, but did not affect TLR4-MD-2 interactions. Thus, our data demonstrate that TLR4 tyrosine phosphorylation is important for signaling and is impaired in endotoxin-tolerant cells, and suggest involvement of Lyn kinase in these processes.
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PMID:Role of TLR4 tyrosine phosphorylation in signal transduction and endotoxin tolerance. 1739 83

In the present study, we have investigated the differential expression of Toll-like receptors [(TLRs) 1-9] in murine peritoneal macrophages in vitro, on treatment with cis-diaminedichloroplatinum (II) (cisplatin). It is demonstrated that cisplatin induces the expression of TLRs and is a potent activator of Toll-signaling pathway. The enhanced expression of TLR2, -3, -4, -5, -6, -7, -8 and -9 is observed at different time intervals after 5 microg ml(-1) cisplatin treatment. The expression of downstream signaling molecules of TLR-signaling pathway--myeloid differentiation factor 88, IRAK1, tumor necrosis factor receptor-associated factor 6 and transcription factors IRF3 and nuclear factor-kappaB (NF-kappaB)--has also been investigated. The expression of TLR2, -3, -4 and -9 was down-regulated in cisplatin-treated macrophages in the presence of inhibitors of mitogen-activated protein kinases and NF-kappaB pathways, suggesting a role of these pathways in cisplatin-induced TLR expression. It is also observed that pre-treatment of macrophages with cisplatin and subsequent incubation with TLR ligands significantly enhanced the production of pro-inflammatory cytokines (tumor necrosis factor-alpha, IFN-gamma, IL-1beta and IL-12) and iNOS expression in macrophages. The data suggest that treatment of macrophages with cisplatin renders them more susceptible to subsequent induction of pro-inflammatory cytokines and iNOS expression by different TLR ligands. It is proposed that the pharmacological reagents like cisplatin can be used to manipulate the innate immune responses, which may be effectively used for the development of novel therapeutic approaches.
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PMID:Differential expression of Toll-like receptors in murine peritoneal macrophages in vitro on treatment with cisplatin. 1744 11

The contribution of bacterial infection to tumorigenesis is usually ascribed to infection-associated inflammation. An alternate view is that direct interaction of bacteria with tumor cells promotes tumor progression. Here, we show that the microenvironment of large tumors favors bacterial survival, which in turn directly accelerates tumor growth by activating tumor cell Toll-like receptors (TLR). Listeria monocytogenes (Lm) survives in the microenvironment of large but not small tumors, resulting in the promotion of tumor growth. Lm did not affect the percentage of regulatory T cells or myeloid suppressor cells in the tumor. Through TLR2 signaling, Lm activated mitogen-activated protein kinases and nuclear factor-kappaB in tumor cells, resulting in the increased production of nitric oxide and interleukin-6 and increased proliferation of tumor cells. All of these effects were abrogated by silencing expression of TLR2, but not TLR4. The interaction of Helicobacter pylori with tumor cells from gastric carcinoma patients resulted in similar effects. These findings provide a new insight into infection-associated tumorigenesis and illustrate the importance of antibiotic therapy to treat tumors with bacterial infiltration.
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PMID:Listeria monocytogenes promotes tumor growth via tumor cell toll-like receptor 2 signaling. 3141 50

Toll-like receptor (TLR) activation is primarily thought to affect antigen-presenting cells (APCs) by inducing an innate immune response that can subsequently activate the adaptive immune system. However, there are increasing data that demonstrate expression and activation of TLRs on T cells, thus providing evidence for a direct role for TLRs in the activation of an adaptive immune response. A study recently demonstrated that Pam3CSK {N-palmitoyl-S-[2,3-bis(palmitoloxy)-(2RS)-propyl]-Cys-Ser-Lys(4)}, a TLR2 agonist lipopeptide, activates T helper 1 (T(H)1) cells and induces interferon-gamma (IFN-gamma) production, even in the absence of TLR1, which differs from its mechanism of activation of APCs. Moreover, whereas Pam3CSK-stimulated IFN-gamma production by T(H)1 cells is ablated in the absence of both myeloid differentiation marker 88 (MyD88), an adaptor protein in the TLR pathway, and interleukin-1 receptor (IL-1R)-associated kinase-4 (IRAK4), the mitogen-activated protein kinases p38 and c-Jun N-terminal kinase (JNK) are still phosphorylated. These data suggest that TLR2 activation of T(H)1 cells occurs through a mechanism different from that described for APCs and provides further evidence of direct TLR activation of the adaptive immune system.
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PMID:T cell activation by TLRs: a role for TLRs in the adaptive immune response. 1778 15

Cell-surface Toll-like receptors (TLRs) initiate innate immune responses, such as inducible nitric oxide synthase (iNOS) induction, to microorganisms' surface pathogens. TLR2 and TLR4 play important roles in gastric mucosa infected with Helicobacter pylori (H. pylori), which contains lipopolysaccharide (LPS) as a pathogen. The present study investigates their physiological roles in the innate immune response of gastric epithelial cells to H. pylori-LPS. Changes in the expression of iNOS, TLR2, and TLR4, as well as downstream activation of mitogen-activated protein kinases and nuclear factor-kappaB (NF-kappaB), were analyzed in normal mouse gastric mucosal GSM06 cells following stimulation with H. pylori-LPS and interferon-gamma. Specific inhibitors for mitogen-activated protein kinases, NF-kappaB, and small interfering RNA for TLR2 or TLR4 were employed. The immunohistochemistry of TLR2 was examined in human gastric mucosa. H. pylori-LPS stimulation induced TLR2 in GSM06 cells, but TLR4 was unchanged. TLR2 induction resulted from TLR4 signaling that propagated through extracellular signal-related kinase and NF-kappaB activation, as corroborated by the decline in TLR4 expression on small interfering RNA treatment and pretreatment with inhibitors. The induction of iNOS and the associated nitric oxide production in response to H. pylori-LPS stimulation were inhibited by declines in not only TLR4 but also TLR2. Increased expression of TLR2 was identified in H. pylori-infected human gastric mucosa. TLR4 signaling initiated by H. pylori-LPS and propagated via extracellular signal-regulated kinase and NF-kappaB activation induced TLR2 expression in gastric epithelial cells. Induced TLR2 cooperated with TLR4 to amplify iNOS induction. This positive correlation may constitute a mechanism for stimulating the innate immune response against various bacterial pathogens, including H. pylori-LPS.
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PMID:Toll-like receptor (TLR) 2 induced through TLR4 signaling initiated by Helicobacter pylori cooperatively amplifies iNOS induction in gastric epithelial cells. 1785 67

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