One hundred fifty years ago glial cells were discovered as a second, non-neuronal, cell type in the central nervous system. To ascribe a function to these new, enigmatic cells, it was suggested that they either glue the neurons together (the Greek word "gammalambdaiotaalpha" means "glue") or provide a robust scaffold for them ("support cells"). Although both speculations are still widely accepted, they would actually require quite different mechanical cell properties, and neither one has ever been confirmed experimentally. We investigated the biomechanics of CNS tissue and acutely isolated individual neurons and glial cells from mammalian brain (hippocampus) and retina. Scanning force microscopy, bulk rheology, and optically induced deformation were used to determine their viscoelastic characteristics. We found that (i) in all CNS cells the elastic behavior dominates over the viscous behavior, (ii) in distinct cell compartments, such as soma and cell processes, the mechanical properties differ, most likely because of the unequal local distribution of cell organelles, (iii) in comparison to most other eukaryotic cells, both neurons and glial cells are very soft ("rubber elastic"), and (iv) intriguingly, glial cells are even softer than their neighboring neurons. Our results indicate that glial cells can neither serve as structural support cells (as they are too soft) nor as glue (because restoring forces are dominant) for neurons. Nevertheless, from a structural perspective they might act as soft, compliant embedding for neurons, protecting them in case of mechanical trauma, and also as a soft substrate required for neurite growth and facilitating neuronal plasticity.
Epithelial-mesenchymal transition (EMT) is a process in which epithelial cells lose their morphology and function and gradually transformed into mesenchymal-like cells. It is considered that EMT is the main cause for tumor recurrence and metastasis. Many factors are involved in the regulation of EMT, such as E-cadherin, transforming growth factor-β, Wnt signaling pathway, microRNA and EMT-related transcription factors. This article reviews the research progress on EMT and the involved mechanisms, and thus to provide a new perspective on cancer therapy in the future.
To investigate the protective effect of histone deacetylase inhibitor NL101 on L-homocysteine (HCA)-induced toxicity in rat neurons, and the toxic effect on normal rat neurons.In the presence of NL101 at various concentrations, HCA (5 mmol/L)-induced changes in cell density, necrosis, and viability were determined in the mixed cultures of rat cortical cells and the primary cultures of rat neurons. The direct effect of NL101 on primary neurons was also observed in the absence of HCA. Histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) was used as the control. After the treatments, cell viability, the density, and morphology of neurons and glial cells, and cell necrosis were determined.In the mixed cultures of cortical cells, NL101 had no effect on HCA (5 mmol/L)-induced cell number reduction at 0.001-10μmol/L; however, it significantly attenuated necrosis at 1-10 μmol/L, and increased neuronal number at 1 μmol/L. NL101 had no effect on the mixed cortical cells in the absence of HCA. In the primary neurons, NL101 reduced neuronal viability and mildly increased necrosis at 1-10 μmol/L in the absence of HCA, while it significantly attenuated HCA-induced neuronal viability reduction at 0.01-10 μmol/L and reduced neuronal necrosis at 1-10 μmol/L. The effects of NL101 were apparently similar to those of SAHA.NL101 has protective effect on HCA-induced neuronal injury but it is neurotoxic at high concentrations, which is similar to the typical histone deacetylase inhibitor SAHA.
: To investigate the effect of nicotinamide phosphoribosyltransferase (NAMPT) inhibitor FK866 on the migration of human non-small cell cancer A549 cells and related mechanism.: The inhibition effect of FK866 on A549 cells was tested by MTT assay. A549 cells were treated with 1.0 and 10.0 nmol/L FK866, and the cell migration was evaluated by modified wound scratch assay. The mRNA expression of E-cadherin and vimentin was detected by real-time RT-PCR, and the expression of ERK1/2 and pERK1/2 was determined by Western blotting.: FK866 inhibited the proliferation of A549 cells in a time-and concentration-dependent manner; after treatment for 72 h, the IC50 of FK866 was 9.55 nmol/L. When 1.0 nmol/L or 10.0 nmol/L FK866 was continuously applied 48 h before and 48 h after a scratch was made in wound scratch assay, the migration of A549 cells was significantly inhibited. However, when the FK866 was applied only 48 h after the scratch, the migration of A549 cells was inhibited by 10.0 nmol/L but not by 1.0 nmol/L FK866. The mRNA expression of E-cadherin and vimentin, and the activated ERK1/2 were significantly increased after 1.0 nmol/L FK866 treatment for 72 h. The pretreatment with nicotinamide adenine dinucleotide (NAD) precursor nicotinamide mononucleotide(1.0 mmol/L) or ERK1/2 inhibitor U0126 (10.0 μmol/L) reversed the up-regulation of E-cadherin and vimentin expression induced by FK866.s: Low concentration of FK866 decreases the migration of A549 cells through the inhibition of NAD level, activation of ERK1/2 and up-regulation of E-cadherin expression. However, it also up-regulates the expression of vimentin, indicating that it may have dual effects on the migration of tumor cells.
Objective: Recently, we reported that pranlukast, an antagonist of cysteinyl leukotriene receptor 1, attenuates ischemic injury in endothelial cells by decreasing reactive oxygen species (ROS) production and inhibiting nuclear factor-κB activation in a leukotriene-independent manner. In this study, we investigated the effect of pranlukast on oxidative stress injury induced by hydrogen peroxide (H2O2) in EA.hy926 cells, a human endothelial cell line, and the possible mechanisms. Methods and Results: We found that H2O2 reduced cell viability and increased lactate dehydrogenase release in a concentration- and time-dependent manner. Necrosis was the main death mode, and the necrotic rate increased 32% after exposure to 220 μM H2O2 for 4 hours. Pretreatment with pranlukast significantly ameliorated the reduced viability and the increased lactate dehydrogenase release and necrosis after exposure to H2O2. We next examined the mechanisms underlying the antinecrotic effects of pranlukast. The results showed that pranlukast attenuated excessive ROS production and ameliorated the reduced superoxide dismuase and glutathione peroxidase activity in EA.hy926 cells exposed to H2O2. Pranlukast also inhibited the collapse of mitochondrial membrane potential (MMP) induced by H2O2. Inhibition of ROS production by N-acetyl-l-cysteine, a powerful antioxidant, reduced MMP collapse and necrosis. Inhibition of MMP collapse by cyclosporine A, a mitochondrial permeability transition inhibitor, attenuated necrosis but failed to reduce ROS production. In addition, we found no expression of 5-lipoxygenase in EA.hy926 cells and zileuton, a 5-lipoxygenase inhibitor, did not affect the cellular injury induced by H2O2. Conclusion: Pranlukast protects endothelial cells from H2O2-induced necrosis by inhibiting ROS-mediated collapse of mitochondrial membrane potential, and this is leukotriene-independent.
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