The Ras/Raf/extracellular signal-regulated kinase (ERK) signaling pathway plays a crucial role in almost all cell functions and therefore requires exquisite control of its spatiotemporal activity. Depending on the cell type and stimulus, ERK activity will mediate different antiproliferative events, such as apoptosis, autophagy and senescence in vitro and in vivo. ERK activity can promote either intrinsic or extrinsic apoptotic pathways by induction of mitochondrial cytochrome c release or caspase-8 activation, permanent cell cycle arrest or autophagic vacuolization. These unusual effects require sustained ERK activity in specific subcellular compartments and could depend on the presence of reactive oxygen species. We will summarize the mechanisms involved in Ras/Raf/ERK antiproliferative functions.

https://febs.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1742-4658.2009.07366.x

ERK and cell death: Mechanisms of ERK‐induced cell death – apoptosis, autophagy and senescence

The MAPK cascades: Signaling components, nuclear roles and mechanisms of nuclear translocation

Electronic waste management approaches: An overview

Mitochondria play a pivotal role in energy metabolism, programmed cell death and oxidative stress. Mutated mitochondrial DNA in diseased cells compromises the structure of key enzyme complexes and, therefore, mitochondrial function, which leads to a myriad of health-related conditions such as cancer, neurodegenerative diseases, diabetes and aging. Early detection of mitochondrial and metabolic anomalies is an essential step towards effective diagnoses and therapeutic intervention. Reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) play important roles in a wide range of cellular oxidation-reduction reactions. Importantly, NADH and FAD are naturally fluorescent, which allows noninvasive imaging of metabolic activities of living cells and tissues. Furthermore, NADH and FAD autofluorescence, which can be excited using distinct wavelengths for complementary imaging methods and is sensitive to protein binding and local environment. This article highlights recent developments concerning intracellular NADH and FAD as potential biomarkers for metabolic and mitochondrial activities.

/pdf/intracellular-coenzymes-as-natural-biomarkers-for-metabolic-3iwj1v2nj2.pdf

Intracellular coenzymes as natural biomarkers for metabolic activities and mitochondrial anomalies.

Influenza A viruses (IAVs), particularly H1N1, H5N1 and H7N9, pose a substantial threat to public health worldwide. Here, we report that MIR2911, a honeysuckle (HS)-encoded atypical microRNA, directly targets IAVs with a broad spectrum. MIR2911 is highly stable in HS decoction, and continuous drinking or gavage feeding of HS decoction leads to a significant elevation of the MIR2911 level in mouse peripheral blood and lung. Bioinformatics prediction and a luciferase reporter assay showed that MIR2911 could target various IAVs, including H1N1, H5N1 and H7N9. Synthetic MIR2911 significantly inhibited H1N1-encoded PB2 and NS1 protein expression, but did not affect mutants in which the MIR2911-binding nucleotide sequences were altered. Synthetic MIR2911, extracted RNA from HS decoction and HS decoction all significantly inhibited H1N1 viral replication and rescued viral infection-induced mouse weight loss, but did not affect infection with a mutant virus in which the MIR2911-binding nucleotide sequences of PB2 and NS1 were altered. Importantly, the inhibitory effect of HS decoction on viral replication was abolished by an anti-MIR2911 antagomir, indicating that the physiological concentration of MIR2911 in HS decoction could directly and sufficiently suppress H1N1 viral replication. MIR2911 also inhibited H5N1 and H7N9 viral replication in vitro and in vivo. Strikingly, administration of MIR2911 or HS decoction dramatically reduced mouse mortality caused by H5N1 infection. Our results demonstrate that MIR2911 is the first active component identified in Traditional Chinese Medicine to directly target various IAVs and may represent a novel type of natural product that effectively suppresses viral infection.

/pdf/honeysuckle-encoded-atypical-microrna2911-directly-targets-2leg0u5gbn.pdf

Honeysuckle-encoded atypical microRNA2911 directly targets influenza A viruses

Benzo[a]pyrene-induced elevation of GSH level protects against oxidative stress and enhances xenobiotic detoxification in human HepG2 cells

Benzo[a]pyrene-induced necrosis in the HepG2 cells via PARP-1 activation and NAD+ depletion

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon ubiquitously existing in the environment. Its metabolites have been shown to cause DNA damage and cellular dysfunction in humans. Panax ginseng C.A. Meyer is a Chinese medicinal herb, and ginsenosides are the main active constituent of ginseng. Accumulating evidence had indicated that ginseng extract and ginsenosides possess cytoprotective effects. In this study, the protective effect of ginsenosides on BaP-induced DNA damage in human dermal fibroblasts (HDFs) and HepG2 cells was investigated. The genotoxic effect of BaP was measured by the comet assay. Results showed that tail moment was increased in BaP-treated cells, but cotreatment of ginsenoside 20(S)-Rg3 can significantly decrease BaP-induced DNA damage. A downstream mechanistic study revealed that 20(S)-Rg3 increased the gene expression of an important phase II detoxifying enzyme NAD(P)H:quinine oxidoreductase 1. The effect was also associated with the activation of protein kinase B (Akt) and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). These results indicated that 20(S)-Rg3 might protect HDFs from BaP-induced DNA damage through the activation of the phosphatidylinositol 3-kinase/Akt/Nrf2 pathway. Our results also demonstrated that 20(S)-Rg3 is a functional ligand of pregnane X receptor (PXR), a nuclear receptor that mediates the induction of drug clearance pathways. Subsequent knockdown of PXR expression by small interfering RNA confirmed the involvement of PXR on the protective effects of 20(S)-Rg3 against BaP-induced DNA damage. In summary, ginsenoside 20(S)-Rg3 can protect against BaP-induced genotoxicity in human cells, suggesting that ginseng may serve as a natural cytoprotective agent against environmental carcinogens.

https://dmd.aspetjournals.org/content/dmd/early/2011/09/28/dmd.111.039503.full.pdf

Cytoprotective Effect of 20(S)-Rg3 on Benzo[a]pyrene-Induced DNA Damage

The energy charge potential (ECP) is the ratio among adenosine 5'-triphosphate (ATP), -diphosphate (ADP), and -monophosphate (AMP); it reflects the high-energy-bond content in biological systems. Under normal physiological conditions, the value of ECP is between 0.7 and 1.0. In this study, two different methods were used to extract adenosine nucleotides (ATP, ADP, and AMP) for determination of the ECP in the C6 glioma and the HepG-2 human hepatoma cell lines. In the first method, cells were removed from culture plates by trypsinization before the nucleotides were extracted using perchloric acid. Some of the trypsinized cells were used for a cell count, thereby allowing the calculation of an average nucleotide level per cell. In the second method, perchloric acid was added directly to the culture plate immediately after the medium was removed. This method resulted in an instant termination of any enzymatic process that might degrade the nucleotides and alter their levels in cells. Adenosine nucleotides were determined by high-performance liquid chromatography. The direct extraction method yielded a total adenosine nucleotide (TAN) level more than twofold higher than that obtained following trypsinization. For the C6 glioma cells, the ratio of ATP to ADP to AMP in the TAN pool was 0.70:0.15:0.15, as compared to 0.36:0.27:0.37 when cells were extracted following trypsinization. Similarly, for the HepG-2 cells, the ratio was 0.62:0.15:0.23 following direct extraction, as compared to 0.15:0.28:0.57 following trypsinization. Using the results from the direct extraction method, the value of the cellular ECP was 0.78 +/- 0.06 for the C6 glioma cells and 0.70 +/- 0.06 for the HepG-2 cells. Compared to the ECP values obtained using the trypsinization method (0.50 +/- 0.05 and 0.29 +/- 0.12, respectively), the ECP values derived using the direct extraction method were significantly greater in both cell lines and were suggestive of the energy status of normal, healthy cells.

Determination of Energy Charge Potential in the C6 Glioma and the HepG-2 Cell Culture

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon ubiquitously existing in the environment. Its metabolites have been shown to cause DNA damage and cellular dysfunction in humans. Panax ginseng C.A. Meyer is a Chinese medicinal herb, and ginsenosides are the main active constituent of ginseng. Accumulating evidence had indicated that ginseng extract and ginsenosides possess cytoprotective effects. In this study, the protective effect of ginsenosides on BaP-induced DNA damage in human dermal fibroblasts (HDFs) and HepG2 cells was investigated. The genotoxic effect of BaP was measured by the comet assay. Results showed that tail moment was increased in BaP-treated cells, but cotreatment of ginsenoside 20(S)-Rg3 can significantly decrease BaP-induced DNA damage. A downstream mechanistic study revealed that 20(S)-Rg3 increased the gene expression of an important phase II detoxifying enzyme NAD(P)H:quinine oxidoreductase 1. The effect was also associated with the activation of protein kinase B (Akt) and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). These results indicated that 20(S)-Rg3 might protect HDFs from BaP-induced DNA damage through the activation of the phosphatidylinositol 3-kinase/Akt/Nrf2 pathway. Our results also demonstrated that 20(S)-Rg3 is a functional ligand of pregnane X receptor (PXR), a nuclear receptor that mediates the induction of drug clearance pathways. Subsequent knockdown of PXR expression by small interfering RNA confirmed the involvement of PXR on the protective effects of 20(S)-Rg3 against BaPinduced DNA damage. In summary, ginsenoside 20(S)-Rg3 can protect against BaP-induced genotoxicity in human cells, suggesting that ginseng may serve as a natural cytoprotective agent against environmental carcinogens.

Cytoprotective Effect of 20(S)-Rg3 on Benzo(a)pyrene-Induced

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