Biochimica et biophysica acta
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Biochim. Biophys. Acta · Jun 2013
Hypoxia-inducible factor prolyl-hydroxylase-2 mediates transforming growth factor beta 1-induced epithelial-mesenchymal transition in renal tubular cells.
Transforming growth factor beta 1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) in kidney epithelial cells plays a key role in renal tubulointerstitial fibrosis in chronic kidney diseases. As hypoxia-inducible factor (HIF)-1α is found to mediate TGF-β1-induced signaling pathway, we tested the hypothesis that HIF-1α and its upstream regulator prolyl hydroxylase domain-containing proteins (PHDs) are involved in TGF-β1-induced EMT using cultured renal tubular cells. Our results showed that TGF-β1 stimulated EMT in renal tubular cells as indicated by the significant decrease in epithelial marker P-cadherin, and the increase in mesenchymal markers α-smooth muscle actin (α-SMA) and fibroblast-specific protein 1 (FSP-1). ⋯ Finally, Smad2/3 inhibitor SB431542 prevented TGF-β1-induced PHD2 decrease, suggesting that Smad2/3 may mediate TGF-β1-induced EMT through PHD2/HIF-1α pathway. It is concluded that TGF-β1 decreased PHD2 expression via an Smad-dependent signaling pathway, thereby leading to HIF-1α accumulation and then EMT in renal tubular cells. The present study suggests that PHD2/HIF-1α is a novel signaling pathway mediating the fibrogenic effect of TGF-β1, and may be a new therapeutic target in chronic kidney diseases.
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Biochim. Biophys. Acta · Jun 2013
Inhibition of c-Jun NH2-terminal kinase stimulates mu opioid receptor expression via p38 MAPK-mediated nuclear NF-κB activation in neuronal and non-neuronal cells.
Despite its potential side effects of addiction, tolerance and withdrawal symptoms, morphine is widely used for reducing moderate and severe pain. Previous studies have shown that the analgesic effect of morphine depends on mu opioid receptor (MOR) expression levels, but the regulatory mechanism of MOR is not yet fully understood. Several in vivo and in vitro studies have shown that the c-Jun NH2-terminal kinase (JNK) pathway is closely associated with neuropathic hyperalgesia, which closely resembles the neuroplastic changes observed with morphine antinociceptive tolerance. ⋯ The p38 MAPK dependent phosphorylation of p65 NF-κB subunit in the nucleus was increased by SP600125 treatment. We also observed by chromatin immunoprecipitation (ChIP) analysis that JNK inhibition led to increased bindings of CBP and histone-3 dimethyl K4, and decreased bindings of HDAC-2, MeCP2, and histone-3 trimethyl K9 to the MOR promoter indicating a transcriptional regulation of MOR by JNK inhibition. All these results suggest a regulatory role of the p38 MAPK and NF-κB pathways in MOR gene expression and aid to our better understanding of the MOR gene regulation.
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Biochim. Biophys. Acta · Jun 2013
Brg1-dependent epigenetic control of vascular smooth muscle cell proliferation by hydrogen sulfide.
Hydrogen sulfide (H2S) can modulate the proliferation of vascular smooth muscle cells. This study was designed to investigate the epigenetic control of vascular smooth muscle cell proliferation in response to H2S. Microarray analysis indicated that Brahma-related gene 1 (Brg1) and proliferation-related genes including proliferating cell nuclear antigen (Pcna), neurotrophin 3 (Ntf3) and platelet-derived growth factor subunit A (Pdgfα) were significantly downregulated by H2S in endothelin-1-stimulated proliferative vascular smooth muscle cells. ⋯ A DNase I hypersensitivity assay revealed that H2S reversed endothelin-1-stimulated Pcna, Ntf3 and Pdgfα chromatin remodeling and vascular smooth muscle cell proliferation. A chromatin immunoprecipitation assay indicated that H2S inhibited the recruitment of Brg1 to the Pcna, Ntf3 and Pdgfα promoters. The results of this study indicate that H2S inhibits vascular smooth muscle cell proliferation via an epigenetic mechanism involving the inhibition of Brg1 transcription and expression, and by reducing the recruitment of Brg1 to the Pcna, Ntf3 and Pdgfα promoter regions.
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Biochim. Biophys. Acta · Jun 2013
The sirtuin inhibitor cambinol impairs MAPK signaling, inhibits inflammatory and innate immune responses and protects from septic shock.
Sirtuins (SIRT1-7) are NAD(+)-dependent histone deacetylases (HDACs) that play an important role in the control of metabolism and proliferation and the development of age-associated diseases like oncologic, cardiovascular and neurodegenerative diseases. Cambinol was originally described as a compound inhibiting the activity of SIRT1 and SIRT2, with efficient anti-tumor activity in vivo. Here, we studied the effects of cambinol on microbial sensing by mouse and human immune cells and on host innate immune responses in vivo. ⋯ At the molecular level, cambinol impaired stimulus-induced phosphorylation of MAPKs and upstream MEKs. Going well along with its powerful anti-inflammatory activity, cambinol reduced TNF blood levels and bacteremia and improved survival in preclinical models of endotoxic shock and septic shock. Altogether, our data suggest that pharmacological inhibitors of sirtuins structurally related to cambinol may be of clinical interest to treat inflammatory diseases.
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Biochim. Biophys. Acta · May 2013
Pro-inflammatory cytokines modulate iron regulatory protein 1 expression and iron transportation through reactive oxygen/nitrogen species production in ventral mesencephalic neurons.
Both inflammatory processes associated with microglia activation and abnormal iron deposit in dopaminergic neurons are involved in the pathogenesis of Parkinson's disease (PD). However, the relationship between neuroinflammation and iron accumulation was not fully elucidated. In the present study, we aimed to investigate whether the pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) released by microglia, could affect cellular iron transportation in primary cultured ventral mesencephalic (VM) neurons. ⋯ In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice, salicylate application could not block DMT1+IRE upregulation in dopaminergic neurons of substantia nigra. These results suggested that IL-1β and TNF-α released by microglia, especially under the condition of iron load, might contribute to iron accumulation in VM neurons by upregulating IRP1 and hepcidin levels through reactive oxygen/nitrogen species production. This might provide a new insight into unraveling that microglia might aggravate this iron mediated neuropathologies in PD.