scholarly journals Isoliquiritigenin Inhibits Interferon-γ-Inducible Genes Expression in Hepatocytes through Down-Regulating Activation of JAK1/STAT1, IRF3/MyD88, ERK/MAPK, JNK/MAPK and PI3K/Akt Signaling Pathways

2015 ◽  
Vol 37 (2) ◽  
pp. 501-514 ◽  
Author(s):  
Shanshan Wu ◽  
Jihua Xue ◽  
Ying Yang ◽  
Haihong Zhu ◽  
Feng Chen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathways ◽  
Interferon Γ ◽  
Akt Signaling ◽  
Janus Kinase ◽  
Expression Levels ◽  
Erk Mapk ◽  
Ifn Γ ◽  
Inducible Genes ◽  
L02 Cells

Background & Aims: The high expression levels of interferon-γ (IFN-γ)-inducible genes correlate positively with liver diseases. The present study aimed to explore the effect of isoliquiritigenin (ISL) on the expression of genes induced by IFN-γ in vitro, and to elucidate the underlying molecular mechanisms. Methods: HepG2 and L02 cells were divided into control, ISL, IFN-γ, and IFN-γ plus ISL groups. The cytotoxicity of compounds to cells was evaluated by Cell Counting Kit 8 (CCK8) assay; the expression levels of chemokine (C-X-C motif) ligand 9 (CXCL9), CXCL10, CXCL11, and interleukin-6 (IL-6) in cells and supernatant were measured by quantitative real time polymerase chain reaction (qRT-PCR) and ELISA, respectively. Moreover, western blot was used to examine the phosphorylated levels of janus kinase (JAK)/signal transducer and activator of transcription 1 (STAT1), nuclear factor (NF)-γB, interferon regulatory factor 3 (IRF3)/myeloid differentiation factor 88 (MyD88), mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/Protein Kinase B (Akt) in HepG2 and L02 cells exposed to ISL, IFN-γ and IFN-γ plus ISL. Results: The results showed that IFN-γ treatment induced the expression of CXCL9, CXCL10, CXCL11, and IL-6 in HepG2 and LO2 cells, which could be significantly and dose-dependently inhibited by ISL treatment (P < 0.05 or P < 0.01), but the inhibitory effect of ISL on IL-6 expression was not so good as on CXCL9, CXCL10, and CXCL11 expression. Furthermore, ISL treatment dose-dependently inhibited the activation of JAK1/STAT1, IRF3/MyD88, extracellular signal-regulated kinase (ERK)/MAPK, c-Jun N-terminal kinase (JNK)/MAPK, and PI3K/Akt signaling pathways (P < 0.05), but had no effect on the activation of JAK2/STAT1, NF-γB and p38/MAPK signaling pathways. Conclusion: We demonstrate that ISL inhibits IFN-γ-induced inflammation in hepatocytes via influencing the activation of JAK1/STAT1, IRF3/MyD88, ERK/MAPK, JNK/MAPK, and PI3K/Akt signaling pathways.

Direct regulation of lipolysis by interleukin-15 in primary pig adipocytes

2004 ◽  
Vol 287 (3) ◽  
pp. R608-R611 ◽  
Author(s):  
Kolapo M. Ajuwon ◽  
Michael E. Spurlock
Keyword(s):  
Protein Kinase ◽  
Muscle Protein ◽  
Interferon Γ ◽  
Janus Kinase ◽  
Dependent Manner ◽  
Kinase C ◽  
Tnf Α ◽  
Interleukin 15 ◽  
Ifn Γ ◽  
Dose Dependent

We recently provided evidence that interleukin-15 (IL-15) is expressed lowly in the pig adipocyte and that interferon-γ (IFN-γ) markedly increases this expression through a pathway regulated in part by protein kinase C (Ajuwon KM, Jacobi SK, Kuske JL, and Spurlock ME. Am J Physiol Regul Integr Comp Physiol 286: R547–R553, 2004). In the present study, we tested the hypothesis that IL-15 acts directly on the adipocyte to regulate lipid accretion by enhancing lipolysis or suppressing lipogenesis. Using recombinant porcine IL-15, we determined that this cytokine stimulates lipolysis in a dose-dependent manner ( P < 0.001). Furthermore, comparative studies with other cytokines showed that IL-15 is more potent in its acute stimulation of lipolysis than either TNF-α, IL-6, or LPS ( P < 0.001). When specific inhibitors of protein kinase A or Janus kinase are present, the lipolytic effect of IL-15 is attenuated ( P < 0.01). These data indicate that, in addition to its regulation of muscle protein accretion and T-cell growth and development, IL-15 also targets the adipocyte directly to alter stimulate lipolysis. Thus, when induced by IFN-γ or other inflammatory mediators, IL-15 may be a significant homeorhetic factor that mobilizes and directs energy away from the adipocyte to other cells during the acute phase of the inflammatory response.

New mimetic peptides of the kinase-inhibitory region (KIR) of SOCS1 through focused peptide libraries

2012 ◽  
Vol 443 (1) ◽  
pp. 231-240 ◽  
Author(s):  
Nunzianna Doti ◽  
Pasqualina L. Scognamiglio ◽  
Stefania Madonna ◽  
Claudia Scarponi ◽  
Menotti Ruvo ◽  
...  
Keyword(s):  
Interferon Γ ◽  
Catalytic Site ◽  
Janus Kinase ◽  
Scanning Method ◽  
Expression Levels ◽  
Interferon Regulatory Factor 1 ◽  
Inhibitory Region ◽  
Inflammatory Processes ◽  
Cytokine Stimulation ◽  
Kinase Inhibitory Region

SOCS (suppressor of cytokine signalling) proteins are negative-feedback regulators of the JAK (Janus kinase)/STAT (signal transducer and activator of transcription) pathway. Their expression levels are low under physiological conditions, but they are up-regulated in response to cytokine stimulation in many immune and inflammatory processes. Overexpression of SOCS1 in keratinocyte clones abrogates the IFNγ (interferon γ)-induced expression of many pro-inflammatory genes and the release of related chemokines by blocking the JAK/STAT pathway. SOCS1 inhibits JAK2 kinase activity by binding the catalytic site of JAK2, with its KIR (kinase-inhibitory region) acting as a pseudo-substrate of the enzyme. In the present study, we screened a focused combinatorial peptide library of KIR to identify new peptides able to mimic its function with an improved affinity towards the JAK2 catalytic site. Using an alanine-scanning method, KIR residues that are crucial for the interaction with JAK2 were unveiled. In this way, the KIR sequence was restricted to a shorter segment and ‘non-essential’ residues were replaced by different amino acids following a simplified combinatorial approach. We selected a new unnatural sequence able to bind to JAK2 with Kd values in the nanomolar range. This peptide was tested in human keratinocyte cultures and reduced the phosphorylation of STAT1 and the expression levels of IRF-1 (interferon regulatory factor-1).

scholarly journals Natural killer T-cell autoreactivity leads to a specialized activation state

Blood ◽  
2008 ◽  
Vol 112 (10) ◽  
pp. 4128-4138 ◽  
Author(s):  
Xiaohua Wang ◽  
Xiuxu Chen ◽  
Lance Rodenkirch ◽  
William Simonson ◽  
Sarah Wernimont ◽  
...  
Keyword(s):  
Natural Killer ◽  
Mapk Pathway ◽  
Nkt Cells ◽  
Interferon Γ ◽  
Janus Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Calcium Flux ◽  
Nkt Cell ◽  
Ifn Γ ◽  
Natural Killer T

Abstract Natural killer T (NKT) cells are innate-like T cells that recognize specific microbial antigens and also display autoreactivity to self-antigens. The nature of NKT-cell autoreactive activation remains poorly understood. We show here that the mitogen-activated protein kinase (MAPK) pathway is operative during human NKT-cell autoreactive activation, but calcium signaling is severely impaired. This results in a response that is biased toward granulocyte macrophage colony-stimulating factor (GM-CSF) secretion because this cytokine requires extracellular signal-regulated kinase (ERK) signaling but is not highly calcium dependent, whereas interferon-γ (IFN-γ), interleukin (IL)–4, and IL-2 production are minimal. Autoreactive activation was associated with reduced migration velocity but did not induce arrest; thus, NKT cells retained the ability to survey antigen presenting cells (APCs). IL-12 and IL-18 stimulated autoreactively activated NKT cells to secrete IFN-γ, and this was mediated by Janus kinase-signal transducers and activators of transcription (JAK-STAT)–dependent signaling without induction of calcium flux. This pathway did not require concurrent contact with CD1d+ APCs but was strictly dependent on preceding autoreactive stimulation that induced ERK activation. In contrast, NKT-cell responses to the glycolipid antigen α-galactosyl ceramide (α-GalCer) were dampened by prior autoreactive activation. These results show that NKT-cell autoreactivity induces restricted cytokine secretion and leads to altered basal activation that potentiates innate responsiveness to costimulatory cytokines while modulating sensitivity to foreign antigens.

Jak1 deficiency leads to enhanced Abelson-induced B-cell tumor formation

Blood ◽  
2003 ◽  
Vol 101 (12) ◽  
pp. 4937-4943 ◽  
Author(s):  
Veronika Sexl ◽  
Boris Kovacic ◽  
Roland Piekorz ◽  
Richard Moriggl ◽  
Dagmar Stoiber ◽  
...  
Keyword(s):  
B Cell ◽  
Cell Lines ◽  
Interferon Γ ◽  
Tumor Formation ◽  
Scid Mice ◽  
Janus Kinase ◽  
Interferon Α ◽  
Ifn Γ ◽  
Transformed Cell Lines

AbstractThe Janus kinase Jak1 has been implicated in tumor formation by the Abelson oncogene. In this study we show that loss of Jak1 does not affect in vitro transformation by v-abl as defined by the ability to induce cytokine-independent B-cell colony formation or establishment of B-cell lines. However, Jak1-deficient, v-abl–transformed cell lines were more tumorgenic than wild-type cells when transplanted subcutaneously into severe combined immunodeficient (SCID) mice or injected intravenously into nude mice. Jak1 deficiency was associated with a loss in the ability of interferon-γ (IFN-γ)to induce growth arrest and/or apoptosis of v-abl–transformed pre-B cells or tumor growth in SCID mice. Moreover, IFN-γ mRNA could be detected in growing tumors, and tumor cells explanted from SCID mice had lost the ability to respond to IFN-γ in 9 of 20 cases, whereas the response to interferon-α (IFN-α) remained intact. Importantly, a similar increase in tumorgenicity was observed when IFN-γ–deficient cells were injected into SCID mice, identifying the tumor cell itself as the main source of IFN-γ. These findings demonstrate that Jak1, rather than promoting tumorgenesis as previously proposed, is critical in mediating an intrinsic IFN-γ–dependent tumor surveillance.

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