A reducing environment stabilizes HIF-2alpha in SH-SY5Y cells under hypoxic conditions

Accumulating evidence suggests that hypoxia-inducible factor-2 (HIF-2) is important for the cellular response to hypoxia. However, it is not clear how HIF-2 is regulated under hypoxic conditions. We investigated kinetic changes in redox status and HIF-2α accumulation in hypoxic SH-SY5Y cells. Our results demonstrated that hypoxia caused a reducing environment and increased HIF-2α protein levels. Experiments with redox modulations (N-acetylcysteine and l-buthionine sulfoximine) confirmed that a reducing environment induced HIF-2α accumulation while an oxidizing environment decreased it. In addition, experiments with SOD mimic, catalase, and exogenous H₂O₂ provided evidence that the presence of H₂O₂ down-regulated the amount of HIF-2α protein. This study offers novel evidence supporting redox status regulation of HIF-2α accumulation under hypoxic conditions.     

Contact of Chlamydophila pneumoniae with type II cell triggers activation of calcium-mediated NF-κB pathway

Nuclear factor-κB (NF-κB) plays an important role in inflammation, proliferation and regulation of apoptosis. The purpose of the present study on type II cells was to investigate whether Chlamydophila pneumoniae contact induces (I) a Ca²⁺ release, that (II) disrupts F-actin/β-tubulin cytoskeletal association with NF-κB/IκBα, leading to (III) a subsequent NF-κB activation.Incubation of rat type II pneumocytes with C. pneumoniae caused an intracellular calcium release within seconds. Confocal laser scanning microscopy (CLSM) revealed that bacterial contact with cell surface leads to a disappearance of the microvilli and disturbs the co-localization between F-actin and NF-κB (p65). Using semi-quantitative CLSM, we show that at 10–30 min IκBα was decreased and p65 or p50 was simultaneously translocated from cytoplasm to the nucleus, resulting in a 19-fold and 17-fold increase versus control cells. During this time no bacteria were internalized into type II cells. The pre-treatment of cells with BAPTA-AM inhibited C. pneumoniae-mediated calcium release. BAPTA-AM or SN50 prevented the C. pneumoniae-induced changes in F-actin cytoskeleton and inhibited NF-κB activation. Paclitaxel reduced C. pneumoniae-mediated changes of β-tubulin cytoskeleton and activation of NF-κB. These results suggest that calcium-mediated cytoskeleton reorganization is involved in C. pneumoniae-induced NF-κB activation in type II cells.     

The role of viral hemorrhagic septicemia virus (VHSV) NV gene in TNF-α- and VHSV infection-mediated NF-κB activation

The role of viral hemorrhagic septicemia virus (VHSV) NV gene in nuclear factor-κB (NF-κB) activation was investigated. Epithelioma papulosum cyprini (EPC) cells pre-treated with tumor necrosis factor (TNF)-α showed a strong resistance against VHSV infection, but cells treated with TNF-α after VHSV infection showed no resistance, suggesting that immediate early TNF-α-mediated responses inhibit VHSV replication. Activation of NF-κB is a key step in TNF-α-mediated immunomodulatory pathways. In this study, activation of NF-κB by TNF-α exposure was inhibited in EPC cells harboring NV gene expressing vectors, indicating that the NV gene of VHSV can suppress TNF-α-mediated NF-κB activation. Furthermore, the NV gene knock-out recombinant VHSV (rVHSV-ΔNV-EGFP) induced significantly higher NF-κB activity in EPC cells than wild-type VHSV, suggesting that VHSV adopted a strategy to suppress early activation of NF-κB in host cells through and NV gene.     

Antioxidant effect of human placenta hydrolysate against oxidative stress on muscle atrophy

Sarcopenia, which refers to the muscle loss that accompanies aging, is a complex neuromuscular disorder with a clinically high prevalence and mortality. Despite many efforts to protect against muscle weakness and muscle atrophy, the incidence of sarcopenia and its related permanent disabilities continue to increase. In this study, we found that treatment with human placental hydrolysate (hPH) significantly increased the viability (approximately 15%) of H₂O₂-stimulated C2C12 cells. Additionally, while H₂O₂-stimulated cells showed irregular morphology, hPH treatment restored their morphology to that of cells cultured under normal conditions. We further showed that hPH treatment effectively inhibited H₂O₂-induced cell death. Reactive oxygen species (ROS) generation and Mstn expression induced by oxidative stress are closely associated with muscular dysfunction followed by atrophy. Exposure of C2C12 cells to H₂O₂ induced abundant production of intracellular ROS, mitochondrial superoxide, and mitochondrial dysfunction as well as myostatin expression via nuclear factor-κB (NF-κB) signaling; these effects were attenuated by hPH. Additionally, hPH decreased mitochondria fission–related gene expression (Drp1 and BNIP3) and increased mitochondria biogenesis via the Sirt1/AMPK/PGC-1α pathway and autophagy regulation. In vivo studies revealed that hPH-mediated prevention of atrophy was achieved predominantly through regulation of myostatin and PGC-1α expression and autophagy. Taken together, our findings indicate that hPH is potentially protective against muscle atrophy and oxidative cell death.     

Rg3 inhibits gemcitabine-induced lung cancer cell invasiveness through ROS-dependent,NF-κB- and HIF-1α-mediated downregulation of PTX3

PTX3, a member of the long pentraxin subfamily, associated with innate immunity is indispensable for resistance to some cancer. Gemcitabine, an analog of cytosine arabinoside, has shown restrained benefits because of profound chemoresistance. The PTX3 expression on GEM in human lung cancer cells have not yet been clarified; the present study aimed to show reactive oxygen species (ROS) mediatory PTX3 expression through distinct mechanisms. Whereas ginsenoside Rg3 is a herbal medicine with strong antitumor activity. Furthermore, we tested the hypothesis; Rg3 abrogates GEM-induced production of ROS-mediated activation of Akt and extracellular signal-regulated kinase (ERK) pathways and inhibits nuclear piling-up of nuclear factor kappa B (NF-κB) and HIF-1α. On the basis of time and dose-dependent manner, our data demonstrated that GEM-induced PTX3 expression was dependent on ROS generation as it was abrogated by pretreatment of lung cancer cells with the free radical scavenger N-acetyl-l -cysteine. Our data demonstrated that PTX3 upregulation by GEM correlated with the time-dependent escalation of NF-κB and HIF-1α in the nucleus resulted from phosphorylation-induced degradation of IκBα, whereas HIF-1α upregulation was NF-κB-dependent. Increase in ROS expression in lung cancer cells on GEM treatment preceded the nuclear accumulation of NF-κB and HIF-1α and suppression of ROS diminished these effects. ERK1/2 and Akt activation mediated the effect of ROS on NF-κB and HIF-1α and their pharmacological inhibition suppressed GEM-induced PTX3. Our study findings reinforced the role regarding PTX3 signaling in GEM-induced resistance and pointed toward an unintended and undesired effect of chemotherapy and to get an active regimen; the synergy was associated with NF-κB downregulation in lung cancer.     

In vitro neuroprotective activity of sesquiterpenoids from the flower buds of Tussilago farfara

Abstract

We have isolated four sesquiterpenoids from Tussilago farfara, a traditional herbal medicine in Korea and China, and investigated the protective effects on LPS-induced neuronal cell death. Four sesquiterpenoids inhibited the production of nitric oxide, prostaglandin E₂ and tumor necrosis factor-α in LPS-treated BV-2 cells through the inhibition of NF-κB pathway. These sesquiterpenoids also inhibited reactive oxygen species (ROS) generation in LPS-treated BV-2 cells. Furthermore, they inhibited LPS-induced neuronal cell death in co-culture system through the inhibition of NF-κB pathway and scavenging of ROS. These results indicated that sesquiterpenoids from Tussilago farfara may have beneficial therapeutic potential for the treatment of neurodegenerative diseases through inhibition of microglial activation.