Differential effects of deoxycholic acid and taurodeoxycholic acid on NF-κB signal transduction and IL-8 gene expression in colonic epithelial cells

2004 ◽  
Vol 286 (6) ◽  
pp. G1000-G1008 ◽  
Author(s):  
M. Mühlbauer ◽  
B. Allard ◽  
A. K. Bosserhoff ◽  
S. Kiessling ◽  
H. Herfarth ◽  
...  
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Epithelial Cells ◽  
Molecular Mechanisms ◽  
Deoxycholic Acid ◽  
Nuclear Translocation ◽  
Binding Activity ◽  
Dominant Negative ◽  
Dependent Manner ◽  
Colonic Epithelial Cells

Several effects of bile acids (BAs) on colonic epithelial cells (CECs) have been described, including induction of proliferation and apoptosis. Some of these effects are mediated through activation of the NF-κB transcriptional system. In this study, we investigated the molecular mechanisms underlying the BA-induced gene expression in CECs. The human CEC line HT-29 and primary human CECs were treated with dilutions of salts of deoxycholic acid (DCA) and taurodeoxycholic acid (TDCA). NF-κB binding activity was analyzed with EMSA, RelA translocation with immunofluorescence, and IκBα- and RelA-phosphorylation with Western blot analysis. IL-8 mRNA and protein expression were assessed by quantitative PCR and ELISA. Functional impact of NF-κB activation was determined by blocking the proteasome activity with MG132 or by preventing IKK activity with a dominant-negative IKKβ delivered by adenoviral dominant-negative (dn) IKKβ (Ad5dnIKKβ). DCA and TDCA induced IL-8 expression in a dose- and time-dependent manner. It is interesting that DCA but not TDCA induced IκBα-phophorylation, RelA translocation, and NF-κB binding activity. Accordingly, the proteasome inhibitor MG132 blocked DCA- but not TDCA-induced IL-8 gene expression. In contrast, TDCA-induced IL-8 gene expression correlated with enhanced RelA phosphorylation, which was blocked by Ad5dnIKKβ. Our data suggest that DCA-induced signal transduction mainly utilized the IκB degradation and RelA nuclear translocation pathway, whereas TDCA primarily induced IL-8 gene expression through RelA phosphorylation. These differences may have implications for the understanding of the pathophysiology of inflammation and carcinogenesis in the gut.

scholarly journals Specific Inhibition of Interferon Signal Transduction Pathways by Adenoviral Infection

2001 ◽  
Vol 276 (50) ◽  
pp. 47136-47142 ◽  
Author(s):  
Theresa D. Joseph ◽  
Dwight C. Look
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Transcription Factor ◽  
Epithelial Cells ◽  
Molecular Mechanisms ◽  
Airway Epithelial Cells ◽  
Signal Transducer ◽  
Airway Epithelial ◽  
Complex Assembly ◽  
Ifn Γ

Adenoviral evolution has generated strategies to resist host cell antiviral systems, but molecular mechanisms for evasion of interferon (IFN) effects by adenoviruses during late-phase infection are poorly defined. In this study, we examined adenovirus type 5 (AdV) effects on IFN-γ-dependent gene expression and Janus family kinase-signal transducer and activator of transcription signaling components in human tracheobronchial epithelial cells. We found that AdV infection specifically inhibited IFN-γ-dependent gene expression in airway epithelial cells without evidence of epithelial cell injury or generation of a soluble extracellular inhibitor. Furthermore, infection with AdV for 18–24 h blocked phosphorylation/activation of the Stat1 transcription factor that regulates IFN-γ-dependent genes. Although AdV also inhibited IFN-α-dependent phosphorylation of Stat1 and Stat2, interleukin-4-dependent phosphorylation of the related transcription factor Stat6 was not affected, indicating that the virus selectively affected specific signaling pathways. Our results indicate that AdV inhibition of the IFN-γ signal transduction cascade occurs through loss of ligand-induced receptor complex assembly and consequent component phosphorylation and suggest that lack of complex assembly is due to decreased expression of the IFN-γR2 chain of the IFN-γ receptor. IFN-γR2 is required at an early step in Janus family kinase-signal transducer and activator of transcription pathway activation and is expressed at low levels in airway epithelial cells, supporting the concept that adenoviral down-regulation of the level of this IFN-γ receptor component allows for persistent modulation of IFN-γ-dependent gene expression.

Neurotensin stimulates IL-8 expression in human colonic epithelial cells through Rho GTPase-mediated NF-κB pathways

2003 ◽  
Vol 284 (6) ◽  
pp. C1397-C1404 ◽  
Author(s):  
Dezheng Zhao ◽  
Sabina Kuhnt-Moore ◽  
Huiyan Zeng ◽  
Jack S. Wu ◽  
Mary P. Moyer ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Protein Production ◽  
Rho Gtpase ◽  
Intestinal Inflammation ◽  
Binding Activity ◽  
Dominant Negative ◽  
Colonic Epithelial Cells ◽  
Mapk Phosphorylation ◽  
Dna Binding Activity ◽  
Rho Family

Neurotensin (NT), a neuropeptide highly expressed in the gastrointestinal tract, participates in the pathophysiology of intestinal inflammation. We recently showed that NT stimulates interleukin-8 (IL-8) expression in NCM460 nontransformed human colonic epithelial cells via both mitogen-activating protein kinase (MAPK)- and NF-κB-dependent pathways. However, the molecular mechanism by which NT induces expression of proinflammatory cytokines such as IL-8 has not been investigated. In this study we show that inhibition of endogenous Rho family proteins (RhoA, Rac1, and Cdc42) by their respective dominant negative mutants inhibits NT-induced IL-8 protein production and promoter activity. Western blot experiments demonstrated that NT strongly activated RhoA, Rac1, and Cdc42. Overexpression of the dominant negative mutants of RhoA, Rac1, and Cdc42 significantly inhibited NT-induced NF-κB-dependent reporter gene expression and NF-κB DNA binding activity. NT also stimulated p38 MAPK phosphorylation, and overexpression of dominant negative mutants of RhoA, Rac1, and Cdc42 did not significantly alter p38 and ERK1/2 phosphorylation in response to NT. Together, our findings indicate that NT-stimulated IL-8 expression is mediated via a Rho-dependent NF-κB-mediated pathway.

Norepinephrine induces calcium spikes and proinflammatory actions in human hepatic stellate cells

2006 ◽  
Vol 291 (5) ◽  
pp. G877-G884 ◽  
Author(s):  
Pau Sancho-Bru ◽  
Ramón Bataller ◽  
Jordi Colmenero ◽  
Xavier Gasull ◽  
Montserrat Moreno ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Portal Hypertension ◽  
Liver Fibrosis ◽  
Hepatic Stellate Cells ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Stellate Cells ◽  
Luciferase Reporter ◽  
Dependent Manner ◽  
Cell Contraction

Catecholamines participate in the pathogenesis of portal hypertension and liver fibrosis through α1-adrenoceptors. However, the underlying cellular and molecular mechanisms are largely unknown. Here, we investigated the effects of norepinephrine (NE) on human hepatic stellate cells (HSC), which exert vasoactive, inflammatory, and fibrogenic actions in the injured liver. Adrenoceptor expression was assessed in human HSC by RT-PCR and immunocytochemistry. Intracellular Ca2+ concentration ([Ca2+]i) was studied in fura-2-loaded cells. Cell contraction was studied by assessing wrinkle formation and myosin light chain II (MLC II) phosphorylation. Cell proliferation and collagen-α1(I) expression were assessed by [3H]thymidine incorporation and quantitative PCR, respectively. NF-κB activation was assessed by luciferase reporter gene and p65 nuclear translocation. Chemokine secretion was assessed by ELISA. Normal human livers expressed α1A-adrenoceptors, which were markedly upregulated in livers with advanced fibrosis. Activated human HSC expressed α1A-adrenoceptors. NE induced multiple rapid [Ca2+]i oscillations (Ca2+ spikes). Prazosin (α1-blocker) completely prevented NE-induced Ca2+ spikes, whereas propranolol (nonspecific β-blocker) partially attenuated this effect. NE caused phosphorylation of MLC II and cell contraction. In contrast, NE did not affect cell proliferation or collagen-α1(I) expression. Importantly, NE stimulated the secretion of inflammatory chemokines (RANTES and interleukin-8) in a dose-dependent manner. Prazosin blocked NE-induced chemokine secretion. NE stimulated NF-κB activation. BAY 11-7082, a specific NF-κB inhibitor, blocked NE-induced chemokine secretion. We conclude that NE stimulates NF-κB and induces cell contraction and proinflammatory effects in human HSC. Catecholamines may participate in the pathogenesis of portal hypertension and liver fibrosis by targeting HSC.

scholarly journals Fibroblast Growth Factors Regulate Prolactin Transcription via an Atypical Rac-Dependent Signaling Pathway

2003 ◽  
Vol 17 (10) ◽  
pp. 1921-1930 ◽  
Author(s):  
Twila A. Jackson ◽  
David M. Koterwas ◽  
Melissa A. Morgan ◽  
Andrew P. Bradford
Keyword(s):  
Gene Expression ◽  
Growth Factors ◽  
Signaling Pathway ◽  
Promoter Activity ◽  
Fibroblast Growth Factors ◽  
Dominant Negative ◽  
Pituitary Cells ◽  
Dependent Manner ◽  
Fibroblast Growth ◽  
Prl Gene

Abstract Fibroblast growth factors (FGFs) play a critical role in pituitary development and in pituitary tumor formation and progression. We have previously characterized FGF signal transduction and regulation of the tissue-specific rat prolactin (rPRL) promoter in GH4 pituitary cells. FGF induction of rPRL transcription is independent of Ras, but mediated by a protein kinase C-δ (PKCδ)-dependent activation of MAPK (ERK). Here we demonstrate a functional role for the Rho family monomeric G protein, Rac1, in FGF regulation of PRL gene expression via an atypical signaling pathway. Expression of dominant negative Rac, but not RhoA or Cdc42, selectively inhibited FGF-induced rPRL promoter activity. Moreover, expression of dominant negative Rac also attenuated FGF-2 and FGF-4 stimulation of MAPK (ERK). However, in contrast to other Rac-dependent signaling pathways, FGF activation of rPRL promoter activity was independent of the c-Jun N-terminal kinase (JNK) and phosphoinositide 3-kinase/Akt cascades. FGFs failed to activate JNK1 or JNK2, and expression of dominant negative JNK or Akt constructs did not block FGF-induced PRL transcription. Consistent with the role of PKCδ in FGF regulation of PRL gene expression, activation of the rPRL promoter was blocked by an inhibitor of phospholipase Cγ (PLCγ) activity. FGF treatment also induced rapid tyrosine phosphorylation of PLCγ in a Rac-dependent manner. These results suggest that FGF-2 and FGF-4 activate PRL gene expression via a novel Rac1, PLCγ, PKCδ, and ERK cascade, independent of phosphoinositol-3-kinase and JNK.

scholarly journals Activation of Nuclear Factor κb and bcl-x Survival Gene Expression by Nerve Growth Factor Requires Tyrosine Phosphorylation of IκBα

2001 ◽  
Vol 152 (4) ◽  
pp. 753-764 ◽  
Author(s):  
Nguyen Truc Bui ◽  
Antonia Livolsi ◽  
Jean-Francois Peyron ◽  
Jochen H.M. Prehn
Keyword(s):  
Gene Expression ◽  
Tyrosine Phosphorylation ◽  
Fluorescent Protein ◽  
Nuclear Translocation ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Nuclear Factor ◽  
Human Neuroblastoma ◽  
Tnf Α

NGF has been shown to support neuron survival by activating the transcription factor nuclear factor-κB (NFκB). We investigated the effect of NGF on the expression of Bcl-xL, an anti–apoptotic Bcl-2 family protein. Treatment of rat pheochromocytoma PC12 cells, human neuroblastoma SH-SY5Y cells, or primary rat hippocampal neurons with NGF (0.1–10 ng/ml) increased the expression of bcl-xL mRNA and protein. Reporter gene analysis revealed a significant increase in NFκB activity after treatment with NGF that was associated with increased nuclear translocation of the active NFκB p65 subunit. NGF-induced NFκB activity and Bcl-xL expression were inhibited in cells overexpressing the NFκB inhibitor, IκBα. Unlike tumor necrosis factor-α (TNF-α), however, NGF-induced NFκB activation occurred without significant degradation of IκBs determined by Western blot analysis and time-lapse imaging of neurons expressing green fluorescent protein–tagged IκBα. Moreover, in contrast to TNF-α, NGF failed to phosphorylate IκBα at serine residue 32, but instead caused significant tyrosine phosphorylation. Overexpression of a Y42F mutant of IκBα potently suppressed NFG-, but not TNF-α–induced NFκB activation. Conversely, overexpression of a dominant negative mutant of TNF receptor-associated factor-6 blocked TNF-α–, but not NGF-induced NFκB activation. We conclude that NGF and TNF-α induce different signaling pathways in neurons to activate NFκB and bcl-x gene expression.

Vitamin D/VDR signaling inhibits colitis by suppressing HIF-1α activation in colonic epithelial cells

2021 ◽  
Author(s):  
Gang Xue ◽  
Ruifang Gao ◽  
Zhuanzhuan Liu ◽  
Na Xu ◽  
Yong Cao ◽  
...  
Keyword(s):  
Vitamin D ◽  
Animal Models ◽  
Epithelial Cells ◽  
Dextran Sulfate ◽  
Hypoxia Inducible Factor ◽  
Dependent Manner ◽  
Trinitrobenzenesulfonic Acid ◽  
Colonic Epithelial Cells ◽  
Bowel Diseases ◽  
Inflammatory Bowel

Vitamin D/vitamin D receptor (VDR) signaling is reported to have a protective effect on the onset or progression of inflammatory bowel diseases (IBD) and hypoxia-inducible factor 1α (HIF-1α) activation is demonstrated to be closely associated with chemical-induced colitis. However, the association between vitamin D/VDR signaling and HIF-1α on IBD development remains a mystery. Here, we showed that HIF-1α expression was largely increased in the colonic epithelial cells of diseased tissues from ulcerative colitis (UC) patients. Consistently, HIF-1α activation was also improved in colonic epithelial cells upon TNFα treatment in a NF-κB pathway-dependent manner. HIF-1α inhibitors treatments ameliorated 2,4,6-trinitrobenzenesulfonic acid (TNBS)- or dextran sulfate sodium (DSS)-induced colitis in animal models. In cell or colitis animal models, vitamin D/VDR signaling suppressed HIF-1α overexpression in colonic epithelial cells via regulating NF-κB pathway, resulting in the inhibition of IFNγ and IL-1β overproductions in these cells. Collectively, these data suggest that vitamin D/VDR signaling relieves colitis development in animal models, at least in part, by suppressing HIF-1α expression in colonic epithelial cells.

Tyrosine kinase inhibitors and antioxidants modulate NF-κB and NOS-II induction in retinal epithelial cells

1998 ◽  
Vol 275 (1) ◽  
pp. C208-C215 ◽  
Author(s):  
Violaine Faure ◽  
Yves Courtois ◽  
Olivier Goureau
Keyword(s):  
Epithelial Cells ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitors ◽  
Intracellular Signaling ◽  
Kinase Inhibitors ◽  
Nuclear Translocation ◽  
Pyrrolidine Dithiocarbamate ◽  
Dependent Manner ◽  
Mrna Accumulation ◽  
Ifn Γ

Bovine retinal pigmented epithelial (RPE) cells express an inducible nitric oxide synthase (NOS-II) after activation with interferon-γ (IFN-γ) and lipopolysaccharide (LPS). Experiments were performed to investigate the effects of tyrosine kinase inhibitors (genistein and herbimycin A) and antioxidants [pyrrolidine dithiocarbamate (PDTC) and butyl hydroxyanisol] on NOS-II induction. The LPS-IFN-γ-induced nitrite release was inhibited in a concentration-dependent manner by these compounds. Analysis by Northern blot showed that this inhibitory effect correlated with a decrease in NOS-II mRNA accumulation. Analysis by electrophoretic mobility shift assay of the activation of the transcription factor nuclear factor-κB (NF-κB) involved in NOS-II induction demonstrated that LPS alone or combined with IFN-γ induced NF-κB binding. NF-κB activation was not changed by the presence of tyrosine kinase inhibitors but was totally prevented by PDTC pretreatment. Immunocytochemistry experiments confirmed the reduction of the nuclear translocation of NF-κB only by PDTC. Our results demonstrated the existence in retinal pigmented epithelial cells of different intracellular signaling pathways in NOS-II induction, since tyrosine kinase inhibitors blocked NOS-II mRNA accumulation without inhibiting NF-κB activation. Furthermore, the LPS-IFN-γ-induced NOS-II mRNA accumulation was sensitive to cycloheximide, suggesting that, in addition to NF-κB, transcriptional factors that require new protein synthesis are involved in NOS-II induction.

scholarly journals Transcriptome changes reveal the genetic mechanisms of the reproductive plasticity of workers in lower termites

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Chenxu Ye ◽  
Humaira Rasheed ◽  
Yuehua Ran ◽  
Xiaojuan Yang ◽  
Lianxi Xing ◽  
...  
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Molecular Mechanisms ◽  
Environmental Changes ◽  
Mapk Pathway ◽  
Specific Expression ◽  
Expression Of Genes ◽  
Genetic Mechanisms ◽  
Ecological Success ◽  
Reproductive Plasticity

Abstract Background The reproductive plasticity of termite workers provides colonies with tremendous flexibility to respond to environmental changes, which is the basis for evolutionary and ecological success. Although it is known that all colony members share the same genetic background and that differences in castes are caused by differences in gene expression, the pattern of the specific expression of genes involved in the differentiation of workers into reproductives remains unclear. In this study, the isolated workers of Reticulitermes labralis developed into reproductives, and then comparative transcriptomes were used for the first time to reveal the molecular mechanisms underlying the reproductive plasticity of workers. Results We identified 38,070 differentially expressed genes and found a pattern of gene expression involved in the differentiation of the workers into reproductives. 12, 543 genes were specifically upregulated in the isolated workers. Twenty-five signal transduction pathways classified into environmental information processing were related to the differentiation of workers into reproductives. Ras functions as a signalling switch regulates the reproductive plasticity of workers. The catalase gene which is related to longevity was up-regulated in reproductives. Conclusion We demonstrate that workers leaving the natal colony can induce the expression of stage-specific genes in the workers, which leads to the differentiation of workers into reproductives and suggests that the signal transduction along the Ras-MAPK pathway crucially controls the reproductive plasticity of the workers. This study also provides an important model for revealing the molecular mechanism of longevity changes.

scholarly journals A Novel Regulatory Axis, CHD1L-MicroRNA 486-Matrix Metalloproteinase 2, Controls Spermatogonial Stem Cell Properties

2018 ◽  
Vol 39 (4) ◽  
Author(s):  
Shan-Shan Liu ◽  
Eithne Margaret Maguire ◽  
Yin-Shan Bai ◽  
Li Huang ◽  
Yurong Liu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cell ◽  
Matrix Metalloproteinase ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Expression Profiles ◽  
Matrix Metalloproteinase 2 ◽  
Small Rna Sequencing ◽  
Growth Properties ◽  
The Matrix

ABSTRACT Spermatogonial stem cells (SSCs) are unipotent germ cells that are at the foundation of spermatogenesis and male fertility. However, the underlying molecular mechanisms governing SSC stemness and growth properties remain elusive. We have recently identified chromodomain helicase/ATPase DNA binding protein 1-like (Chd1l) as a novel regulator for SSC survival and self-renewal, but how these functions are controlled by Chd1l remains to be resolved. Here, we applied high-throughput small RNA sequencing to uncover the microRNA (miRNA) expression profiles controlled by Chd1l and showed that the expression levels of 124 miRNA transcripts were differentially regulated by Chd1l in SSCs. KEGG pathway analysis shows that the miRNAs that are differentially expressed upon Chd1l repression are significantly enriched in the pathways associated with stem cell pluripotency and proliferation. As a proof of concept, we demonstrate that one of the most highly upregulated miRNAs, miR-486, controls SSC stemness gene expression and growth properties. The matrix metalloproteinase 2 (MMP2) gene has been identified as a novel miR-486 target gene in the context of SSC stemness gene regulation and growth properties. Data from cotransfection experiments showed that Chd1l, miR-486, and MMP2 work in concert in regulating SSC stemness gene expression and growth properties. Finally, our data also revealed that MMP2 regulates SSC stemness gene expression and growth properties through activating β-catenin signaling by cleaving N-cadherin and increasing β-catenin nuclear translocation. Our data demonstrate that Chd1l–miR-486–MMP2 is a novel regulatory axis governing SSC stemness gene expression and growth properties, offering a novel therapeutic opportunity for treating male infertility.

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