The conformation change of Bcl-2 is involved in arsenic trioxide-induced apoptosis and inhibition of proliferation in SGC7901 human gastric cancer cells

<p>Abstract</p> <p>Background</p> <p>Arsenic trioxide has been established as a first-line agent for treating acute promyelocytic leukemia. Experimental data suggest that arsenic trioxide also can have a potential use as chemotherapeutic agent for other malignancies. The precise mechanisms of action of arsenic trioxide have though not been elucidated. As the role of Bcl-2 in arsenic trioxide-mediated cell apoptosis and conformation change of Bcl-2 in response to arsenic trioxide treatment has not been studied. The aim of the present study was to determine whether conformation change of Bcl-2 is involved in the action of arsenic trioxide.</p> <p>Methods</p> <p>Human gastric cancer SGC7901 cells were exposed to different concentrations of arsenic trioxide. Proliferation was measured by using the Kit-8 cell counting assay. Analysis of nuclear morphology was observed by DAPI staining. The apoptosis rates of cells treated with arsenic trioxide were analyzed by flow cytometry using Annexin V-FITC staining. The conformation change of Bcl-2 and Bax activation were detected by immunostaining and Western blot analysis. Total expression of Bcl-2 and Bax were examined by Western blot analysis.</p> <p>Results</p> <p>Arsenic trioxide inhibited the growth of human gastric cancer SGC7901 cells and induced apoptosis. There were two Bcl-2 phenotypes coexisting in SGC7901 cells and the Bcl-2 cytoprotective phenotype could change into a cytodestructive phenotype following conformational change of Bcl-2, triggered by arsenic trioxide exposure. Bax activation might also be involved in arsenic trioxide-induced Bcl-2 conformational change. Arsenic trioxide did not change levels of total Bcl-2 expression, but up-regulated total Bax expression for the treatment time ranging from 3 to 24 hours.</p> <p>Conclusion</p> <p>Arsenic trioxide induces apoptosis through induction of Bcl-2 conformational change, Bax activation and up-regulation of total Bax expression rather than affecting total Bcl-2 expression in human gastric cancer SGC7901 cells. The conformational change of Bcl-2 may be a novel described mechanism of arsenic trioxide-induced apoptosis in cancer cells.</p

Rheumatoid meningitis: a rare neurological complication of rheumatoid arthritis

ObjectiveTo describe the clinical and neuroimaging characteristics of rheumatoid meningitis (RM) in Chinese patients. MethodsThe patients admitted to our hospital with the diagnosis of RM in the past 8 years were retrospectively analyzed. ResultsSix patients with RM were identified among 933 patients admitted with rheumatoid arthritis (RA). The symptoms of meningitis occurred after onset of arthritis in five patients and before onset in one. Headache (n=6), hyperacute focal neurological deficits (n=4) and seizures (n=3) were the most prevalent symptoms. The nadir modified Rankin Scale score was ≥3 in five patients. Rheumatoid factor was elevated in all patients, and interleukin-6 levels in cerebrospinal fluid were dramatically elevated in three of four tested patients. Magnetic resonance imaging of the brain revealed that the meninges were affected in all patients and the cerebral parenchyma was affected in one patient. The lesions were generally located in the frontoparietal region and showed restricted diffusion along the adjacent subarachnoid space. RM occurred during disease-modifying therapy in four patients. In the acute episode, three patients improved on tocilizumab and the other three improved on pulse corticosteroids. For maintenance therapy, two patients received combined therapy of tocilizumab and other immunosuppressive agents, one received adalimumab and methotrexate, and two received low-dose oral corticosteroids with an immunosuppressive agent. Five patients had a good outcome, and one died of Pneumocystis jirovecii pneumonia after stabilization of his neurologic conditions. No relapse of RM occurred on immunotherapy during follow-up. ConclusionsChinese patients with RM share some remarkable clinical and neuroimaging features and respond well to appropriate immunotherapy. Tocilizumab could be a treatment option for this severe complication of RA

Acetylation Regulates Gluconeogenesis by Promoting PEPCK1 Degradation via Recruiting the UBR5 Ubiquitin Ligase

Protein acetylation has emerged as a major mechanism in regulating cellular metabolism. Whereas most glycolytic steps are reversible, the reaction catalyzed by pyruvate kinase is irreversible and the reverse reaction requires phosphoenolpyruvate carboxykinase (PEPCK1) to commit for gluconeogenesis. Here we show that acetylation regulates the stability of the gluconeogenic rate limiting enzyme PEPCK1, thereby modulating cellular response to glucose. High glucose destabilizes PEPCK1 by stimulating its acetylation. PEPCK1 is acetylated by the P300 acetyltransferase and this acetylation stimulates the interaction between PEPCK1 and UBR5, a HECT domain containing E3 ubiquitin ligase, therefore promoting PEPCK1 ubiquitinylation and degradation. Conversely, SIRT2 deacetylates and stabilizes PEPCK1. These observations represent an example that acetylation targets a metabolic enzyme to a specific E3 ligase in response to metabolic condition changes. Given that increased levels of PEPCK is linked with type II diabetes, this study also identifies potential therapeutic targets for diabetes

TLR3 Ligand PolyI:C Prevents Acute Pancreatitis Through the Interferon-β/Interferon-α/β Receptor Signaling Pathway in a Caerulein-Induced Pancreatitis Mouse Model

Acute pancreatitis (AP) is a common and devastating inflammatory disorder of the pancreas. However, there are still no effective treatments available for the disease. Therefore, it is important to discover new therapeutic targets and strategies for better treatment and prognosis of AP patients. Toll-like receptor 3 (TLR3) ligand polyI:C is a double-stranded RNA mimic that can be used as an immune stimulant. Our current study indicates that polyI:C exerted excellent anti-inflammatory effects in a caerulein-induced AP mouse model and taurocholate-induced pancreatic acinar cell line injury model. We found that polyI:C triggers type I interferon (IFN) production and downstream IFN-α/β receptor (IFNAR)-dependent signaling, which play key roles in protecting the pancreas from inflammatory injury. Knockout of IFN-β and IFNAR in mice abolished the preventive effects of polyI:C on caerulein-induced AP symptoms, which include pancreatic edema, neutrophil infiltration, the accumulation of reactive oxygen species (ROS), and inflammatory gene expression. Treating pancreatic acinar 266-6 cells with an IFNAR inhibitor, which blocks the interaction between type I IFN and IFNAR, diminishes the downregulation of oxidative stress by polyI:C. Additionally, a subsequent transcriptome analysis on the role of polyI:C in treating pancreatitis suggested that chemotaxis of neutrophils and the production of ROS were inhibited by polyI:C in the pancreases damaged by caerulein injection. Thus, polyI:C may act as a type I IFN inducer to alleviate AP, and it has the potential to be a promising therapeutic agent used at the early stages of AP

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Experimental Investigation of the Desalination Process for Direct Contact Membrane Distillation Using Plate and Frame Membrane Module

Through experiments, the effect of membrane material selection and operating conditions on permeate fluxes in direct contact membrane distillation (DCMD) desalination was investigated. The experiment used a plate and frame membrane module, and with nine different hydrophobic porous membranes, a comparative analysis of the desalination performance of 3 wt% NaCl solution was performed. The results of this experiment were compared to find out the effect of different materials, pore sizes and membrane thicknesses on the permeate flux under same operating conditions. Further, a three-factor, three-level orthogonal experiment was designed. The effects of hot-side temperature, hot-side inlet flow and cold-side inlet flow on the permeate flux of PTFE membranes with a pore size of 0.22 μm were investigated when the temperature on the cold side was set at 20 °C. The results showed that in the DCMD experiments, both PTFE and PVDF membranes performed well, and that hot-side inlet temperatures and cold-side inlet flow rates had significant effects on the permeate flux

The protective effects of Lipoxin A(4) during the early phase of severe acute pancreatitis in rats

Objective. Our aim was to investigate the protective effects of a Lipoxin A(4) analogue (LXA(4)) in the early phase of acute pancreatitis in rats. Materials and methods. Severe acute pancreatitis (SAP) was induced by injection of 5% sodium taurocholate into the pancreatic duct. Rats with SAP were treated with LXA(4) (0.1 mg/kg), 10 min after the 5% sodium taurocholate injection, after which LXA(4) was administrated every 8 hours, three times (LXA(4) group). The sham group was only given the vehicle after operation. Plasma amylase activity, serum levels of interleukin-1 (IL-1), IL-6, and tumor necrosis factor-alpha (TNF-alpha) were measured at 4, 12, and 24 h after induction of SAP. The pancreatic index and histopathologic observations were evaluated and the expression of intercellular adhesion molecule-1 (ICAM-1) and NF-kappa B p65 in the pancreas, and the expression of ICAM-1 in the lungs were detected by immunohistochemistry. Results. LXA(4) treated rats had lower serum levels of TNF-alpha, IL-1, and IL-6 at all time points measured (p < 0.05), but significantly differed in plasma amylase activity only at 24 h as compared with the SAP group. The pancreatic index and the scores of pancreatitic histopathologic evaluations were lower in the LXA(4) group as compared to the SAP group. Immunohistochemistry showed that LXA(4) attenuated the expression of ICAM-1 and NF-kappa B p65 in the pancreas, as well as the expression of ICAM-1 in the lungs in animals with pancreatitis (p < 0.05). Conclusions. We demonstrate that LXA(4) has protective effects in experimental SAP, which may be achieved by inhibiting the NF-kappa B signalling pathway, thereby reducing the production of proinflammatory cytokines