Similar Datasets
Project description:BMP6 is an iron-sensing cytokine produced by liver sinusoidal endothelial cells (LSECs). The transcription factor NRF2 was proposed to induce Bmp6 expression in response to iron-triggered oxidative stress, and NRF2 knock-out mice were shown not capable of regulating Bmp6 in response to massive diet-imposed iron overload. However, LSEC Bmp6 expression levels in the hemochromatosis mouse model reflect hepatocytic, not endothelial iron content. Hence, it is not fully resolved how iron signals translate into alterations of Bmp6 mRNA levels. To further explore the mechanisms of Bmp6 regulation, we employed female mice aged 10-11 months that are hallmarked by hepatocytic, but not LSEC iron accumulation and decreased transferrin saturation, hinting at the absence of systemic iron overload. We found that LSECs of aged mice exhibit increased Bmp6 levels as compared to young controls, but do not show oxidative stress or a transcriptional signature characteristic of activated NFR2-mediated signaling in FACS-sorted LSECs. We further observed that primary murine LSECs derived from both wild-type and NRF2 knock-out mice induce Bmp6 in response to acute iron exposure. By analyzing RNA sequencing data of FACS-sorted LSECs from aged versus young mice, as well as upon acute injections of iron citrate in young mice, we identified ETS1 as a candidate transcription factor involved in Bmp6 regulation. By conducting siRNA-mediated knock-down and small-molecule treatments in primary LSECs, we show that Bmp6 transcription is regulated in an NRF2-independent manner via ETS1, which is activated downstream of p38 MAP kinase-mediated signaling. This knowledge expands the understanding of Bmp6 transcriptional control in both iron-triggered oxidative stress and under the conditions uncoupled to LSECs reactive oxygen species levels.
2024-01-25 | GSE235692 | GEO
Project description:BMP6 is an iron-sensing cytokine produced by liver sinusoidal endothelial cells (LSECs). The transcription factor NRF2 was proposed to induce Bmp6 expression in response to iron-triggered oxidative stress, and NRF2 knock-out mice were shown not capable of regulating Bmp6 in response to massive diet-imposed iron overload. However, LSEC Bmp6 expression levels in the hemochromatosis mouse model reflect hepatocytic, not endothelial iron content. Hence, it is not fully resolved how iron signals translate into alterations of Bmp6 mRNA levels. To further explore the mechanisms of Bmp6 regulation, we employed female mice aged 10-11 months that are hallmarked by hepatocytic, but not LSEC iron accumulation and decreased transferrin saturation, hinting at the absence of systemic iron overload. We found that LSECs of aged mice exhibit increased Bmp6 levels as compared to young controls, but do not show oxidative stress or a transcriptional signature characteristic of activated NFR2-mediated signaling in FACS-sorted LSECs. We further observed that primary murine LSECs derived from both wild-type and NRF2 knock-out mice induce Bmp6 in response to acute iron exposure. By analyzing RNA sequencing data of FACS-sorted LSECs from aged versus young mice, as well as upon acute injections of iron citrate in young mice, we identified ETS1 as a candidate transcription factor involved in Bmp6 regulation. By conducting siRNA-mediated knock-down and small-molecule treatments in primary LSECs, we show that Bmp6 transcription is regulated in an NRF2-independent manner via ETS1, which is activated downstream of p38 MAP kinase-mediated signaling. This knowledge expands the understanding of Bmp6 transcriptional control in both iron-triggered oxidative stress and under the conditions uncoupled to LSECs reactive oxygen species levels.
2024-01-25 | GSE235975 | GEO
Project description:Mycobacterium abscessus (Mabs), a non-tuberculous mycobacterium, is an emerging and rapidly growing opportunistic pathogen that is frequently found in patients with cystic fibrosis and in immunosuppressed patients. Its high tolerance to antibiotics is of great concern for public health. In this study, our results showed that human THP-1-derived macrophages infected with M. abscessus presented an increase in ROS production and cell necrosis. In addition, M. abscessus infection triggered activation of the Nuclear factor E2-related factor 2 (Nrf2) signaling pathway, and the induction of HO-1 and NQO1 expression levels. Interestingly, pretreatment of macrophages with sulforaphane (SFN), an activator of the antioxidant key regulator Nrf2, followed by M. abscessus infection significantly decreased mycobacterial burden. We demonstrated that this reduction in mycobacterial growth was due to an activation in cell apoptosis in SFN-pretreated and M. abscessus-infected macrophages. Pretreatment with specific MAPK inhibitors, PD98059, SP600125, and SB203580 to ERK, JNK, and p38 respectively, failed to inhibit induction of Nrf2 expression, suggesting that Nrf2 signaling pathway was upstream of MAPK signaling. Activation of cell apoptosis was caspase 3/7 independent but p38 MAPK dependent. Moreover, p38 MAPK induction was abolished in macrophages transfected with Nrf2 siRNA. In addition, p38 inhibitor abolished Nrf2-dependent apoptosis in infected macrophages. Taken together, our results indicate that modulation of the Nrf2 signaling using Nrf2 activators may help potentiate the actual drug therapies used to treat mycobacterial infection.
| S-EPMC4979433 | biostudies-literature
Project description:Iron is critical for life but toxic in excess because of iron-catalysed formation of pro-oxidants that cause tissue damage in a range of disorders. The Nrf2 transcription factor orchestrates cell-intrinsic protective antioxidant responses, and the peptide hormone hepcidin maintains systemic iron homeostasis, but is pathophysiologically decreased in haemochromatosis and beta-thalassaemia. Here, we show that Nrf2 is activated by iron-induced, mitochondria-derived pro-oxidants and drives Bmp6 expression in liver sinusoid endothelial cells, which in turn increases hepcidin synthesis by neighbouring hepatocytes. In Nrf2 knockout mice, the Bmp6-hepcidin response to oral and parenteral iron is impaired and iron accumulation and hepatic damage are increased. Pharmacological activation of Nrf2 stimulates the Bmp6-hepcidin axis, improving iron homeostasis in haemochromatosis and counteracting the inhibition of Bmp6 by erythroferrone in beta-thalassaemia. We propose that Nrf2 links cellular sensing of excess toxic iron to control of systemic iron homeostasis and antioxidant responses, and may be a therapeutic target for iron-associated disorders.
| S-EPMC6609153 | biostudies-literature
Project description:Hepcidin is a key iron regulatory hormone that controls expression of the iron exporter ferroportin to increase the iron supply when needed to support erythropoiesis and other essential functions, but to prevent the toxicity of iron excess. The bone morphogenetic protein (BMP)-SMAD signaling pathway, through the ligand BMP6 and the co-receptor hemojuvelin, is a central regulator of hepcidin transcription in the liver in response to iron. Here, we show that dietary iron loading has a residual ability to induce Smad signaling and hepcidin expression in Bmp6-/- mice, effects that are blocked by a neutralizing BMP2/4 antibody. Moreover, BMP2/4 antibody inhibits hepcidin expression and induces iron loading in wildtype mice, whereas a BMP4 antibody has no effect. Bmp2 mRNA is predominantly expressed in endothelial cells of the liver, where its baseline expression is higher, but its induction by iron is less robust than Bmp6. Mice with a conditional ablation of Bmp2 in endothelial cells exhibit hepcidin deficiency, serum iron overload, and tissue iron loading in liver, pancreas and heart, with reduced spleen iron. Together, these data demonstrate that in addition to BMP6, endothelial cell BMP2 has a non-redundant role in hepcidin regulation by iron.
| S-EPMC5986189 | biostudies-literature
Project description:Environmental particle inhalation and persistent herpesvirus infection are omnipresent and associated with chronic lung diseases. Previously, we showed that pulmonary exposure to soot-like carbonaceous nanoparticles (CNP) or fibre-shaped engineered double-walled carbon nanotubes (DWCNT) induced an increase of lytic virus protein expression in latently murine gammaherpesvirus 68 (MHV-68) infected mouse lungs, with a similar pattern as acute infection suggesting virus reactivation. However, the molecular mechanisms underlying herpesvirus reactivation as well as herpesvirus reactivation associated disease exacerbation caused by particle exposure remain unclear. Here, we investigated the effects of environmental relevant repeated particle exposure and herpesvirus reactivation mechanistically, and therapeutically. In the MHV-68 mouse model, we identified elevated lung inflammation and emphysema-like injury after repetitive CNP exposure. We further uncovered that CNP reactivated latent herpesvirus mainly in CD11b+ macrophages. Mechanistically, ERK1/2, JNK and p38 MAPK were rapidly activated after CNP and DWCNT exposure in persistently MHV-68 infected bone marrow-derived macrophages, followed by upregulation of viral gene expression and increased viral titer but without generating a pro-inflammatory transcriptional signature. Pharmacological inhibition of p38 activation abrogated CNP but not DWCNT triggered virus reactivation. In vivo, p38 inhibitor pretreatment of latently infected mice also attenuated CNP exposure induced MHV-68 reactivation. Our findings suggest that particle pollution is an environmental challenge to trigger herpesvirus reactivation and related chronic lung disease by activating latent herpesvirus via p38 MAPK dependent signalling. Pharmacological p38 inhibition might serve as a protective target to alleviate particle exposure related chronic lung disease exacerbations.
2023-09-29 | GSE223818 | GEO
Project description:Diarrhea is a common manifestation of gastrointestinal disorders. Diarrhea-induced losses of fluid and electrolyte could lead to dehydration and electrolyte imbalances, resulting in significant morbidity and mortality, especially in children living in developing countries. Somatostatin, a peptide hormone secreted by D-cells, plays an important role in regulating motility and intestinal Na(+) absorption. Although octreotide, a somatostatin analog, is used to treat diarrhea, its mechanisms of action are unclear. Here we showed that octreotide increased brush-border membrane Na(+)/H(+) exchanger 8 (NHE8) expression in the small intestine to the exclusion of other NHEs that participate in Na(+) absorption. The same effect also occurred in human intestinal cells (Caco-2). We found that the increase of NHE8 expression by somatostatin required p38 mitogen-activated protein kinase (MAPK) activation. Furthermore, the somatostatin receptor SSTR2 antagonist CYN154806 could abolish somatostatin-induced NHE8 expression and p38 MAPK phosphorylation. Thus our data provided the first concrete evidence indicating that somatostatin stimulates intestinal Na(+) absorption by increasing intestinal NHE8 expression through the SSTR2-p38 MAPK pathway.
| S-EPMC3043635 | biostudies-literature
Project description:Down-regulation of overabundant interleukin (IL)-8 present in cystic fibrosis (CF) airways could ease excessive neutrophil burden and its deleterious consequences for the lung. IL-8 production in airway epithelial cells, stimulated with e.g. inflammatory cytokines IL-1? and tumor necrosis factor (TNF)-?, is regulated by several signaling pathways including nuclear factor (NF)-?B and p38 mitogen-activated protein kinase (MAPK). We previously demonstrated that the anti-inflammatory drugs dexamethasone and ibuprofen suppress NF-?B; however, only dexamethasone down-regulates cytokine-induced IL-8, highlighting the importance of non-NF-?B mechanisms. Here, we tested the hypothesis that down-regulation of cytokine-induced IL-8 requires modulation of the MAPK phosphatase (MKP)-1/p38 MAPK/mRNA stability pathway. The effects of dexamethasone (5 nm) and ibuprofen (480 ?m) on this pathway and IL-8 were studied in CF (CFTE29o-, CFBE41o-) and non-CF (1HAEo-) airway epithelial cells. We observed that dexamethasone, but not ibuprofen, destabilizes IL-8 mRNA and up-regulates MKP-1 mRNA. Further, siRNA silencing of MKP-1, via p38 MAPK, leads to IL-8 overproduction and diminishes the anti-IL-8 potential of dexamethasone. However, MKP-1 overexpression does not significantly alter IL-8 production. By contrast, direct inhibition of p38 MAPK (inhibitor SB203580) efficiently suppresses IL-8 with potency comparable with dexamethasone. Similar to dexamethasone, SB203580 decreases IL-8 mRNA stability. Dexamethasone does not affect p38 MAPK activation, which excludes its effects upstream of p38 MAPK. In conclusion, normal levels of MKP-1 are necessary for a full anti-IL-8 potential of pharmacological agents; however, efficient pharmacological down-regulation of cytokine-induced IL-8 also requires direct effects on p38 MAPK and mRNA stability independently of MKP-1.
| S-EPMC3091209 | biostudies-literature
Project description:BackgroundThe accumulation of astrocytes around senile plaques is one of the pathological characteristics in Alzheimer's disease (AD). Serum amyloid A (SAA), known as a major acute-phase protein, colocalizes with senile plaques in AD patients. Here, we demonstrate the role of SAA in astrocyte migration.MethodsThe effects of SAA on astrocyte activation and accumulation around amyloid β (Aβ) deposits were detected in APP/PS1 transgenic mice mated with Saa3-/- mice. SAA expression, astrocyte activation, and colocalization with Aβ deposits were evaluated in mice using immunofluorescence staining and/or Western blotting. The migration of primary cultures of mouse astrocytes and human glioma U251 cells was examined using Boyden chamber assay and scratch-would assay. The actin and microtubule networks, protrusion formation, and Golgi apparatus location in astrocytes were determined using scratch-would assay and immunofluorescence staining.ResultsSaa3 expression was significantly induced in aged APP/PS1 transgenic mouse brain. Saa3 deficiency exacerbated astrocyte activation and increased the number of astrocytes around Aβ deposits in APP/PS1 mice. In vitro studies demonstrated that SAA inhibited the migration of primary cultures of astrocytes and U251 cells. Mechanistic studies showed that SAA inhibited astrocyte polarization and protrusion formation via disrupting actin and microtubule reorganization and Golgi reorientation. Inhibition of the p38 MAPK pathway abolished the suppression of SAA on astrocyte migration and polarization.ConclusionsThese results suggest that increased SAA in the brain of APP/PS1 mice inhibits the migration of astrocytes to amyloid plaques by activating the p38 MAPK pathway.
| S-EPMC7456509 | biostudies-literature
Project description:Background and purposeThis study aimed to evaluate the anti-hepatitis C virus (HCV) activity of andrographolide, a diterpenoid lactone extracted from Andrographis paniculata, and to identify the signalling pathway involved in its antiviral action.Experimental approachUsing HCV replicon and HCVcc infectious systems, we identified anti-HCV activity of andrographolide by measuring protein and RNA levels. A reporter activity assay was used to determine transcriptional regulation of anti-HCV agents. A specific inhibitor and short hairpin RNAs were used to investigate the mechanism responsible for the effect of andrographolide on HCV replication.Key resultsIn HCV replicon and HCVcc infectious systems, andrographolide time- and dose-dependently suppressed HCV replication. When combined with IFN-?, an inhibitor targeting HCV NS3/4A protease (telaprevir), or NS5B polymerase (PSI-7977), andrographolide exhibited a significant synergistic effect. Andrographolide up-regulated the expression of haeme oxygenase-1 (HO-1), leading to increased amounts of its metabolite biliverdin, which was found to suppress HCV replication by promoting the antiviral IFN responses and inhibiting NS3/4A protease activity. Significantly, these antiviral effects were attenuated by an HO-1-specific inhibitor or HO-1 gene knockdown, indicating that HO-1 contributed to the anti-HCV activity of andrographolide. Andrographolide activated p38 MAPK phosphorylation, which stimulated nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated HO-1 expression, and this was found to be associated with its anti-HCV activity.Conclusions and implicationsOur results demonstrate that andrographolide has the potential to control HCV replication and suggest that targeting the Nrf2-HO-1 signalling pathway might be a promising strategy for drug development.
| S-EPMC3874710 | biostudies-literature