Mobilization of xanthine oxidase from the gastrointestinal tract in acute pancreatitis

BACKGROUND: Xanthine oxidoreductase has been proposed to play a role in the development of local and systemic effects of acute pancreatitis. Under physiologic conditions, the enzyme exists mainly as xanthine dehydrogenase (XDH) but can be converted by proteolytic cleavage to its superoxide-generating form xanthine oxidase (XOD). In addition to its intracellular location XDH/XOD is also associated to the polysaccharide chains of proteoglycans on the external endothelial cell membrane. In the early stages of acute pancreatitis, this enzyme seems to be arising from its mobilization from the gastrointestinal endothelial cell surface. Taking into account the ability of α-amylase to hydrolyze the internal α-1,4 linkages of polysaccharides, we wanted to elucidate the involvement of α-amylase in XDH/XOD mobilization from the gastrointestinal endothelial cell surface and the relevance of the ascitic fluid (AF) as the source of α-amylase in experimental acute pancreatitis. METHODS: Acute pancreatitis was induced in male Wistar rats by intraductal administration of 5% sodium taurocholate. In another experimental group 3000 U/Kg α-amylase was i.v. administered. The concentrations of XDH, XOD and α-amylase in plasma and AF and myeloperoxidase (MPO) in lung have been evaluated. In additional experiments, the effect of peritoneal lavage and the absorption of α-amylase present in the AF by an isolated intestine have been determined. RESULTS: Similar increase in XDH+XOD activity in plasma was observed after induction of acute pancreatitis and after i.v. administration of α-amylase. Nevertheless, the conversion from XDH to XOD was only observed in the pancreatitis group. Lung inflammation measured as MPO activity was observed only in the pancreatitis group. In addition peritoneal lavage prevented the increase in α-amylase and XDH+XOD in plasma after induction of pancreatitis. Finally, it was observed that α-amylase is absorbed from the AF by the intestine. CONCLUSIONS: During the early stages of acute pancreatitis, α-amylase absorbed from AF through the gastrointestinal tract could interfere with the binding of XDH/XOD attached to glycoproteins of the endothelial cells. Proteolytic enzymes convert XDH into its oxidase form promoting an increase in circulating XOD that has been reported to be one of the mechanisms involved in the triggering of the systemic inflammatory process

Localisation of Human Papillomavirus 16 E7 Oncoprotein Changes with Cell Confluence

E7 is one of the best studied proteins of human papillomavirus type 16, largely because of its oncogenic potential linked to cervical cancer. Yet the sub-cellular location of E7 remains confounding, even though it has been shown to be able to shuttle between the nucleus and the cytoplasm. Here we show with immunocytochemistry that E7 proteins are located in the nucleus and cytoplasm in sub-confluent cells, but becomes cytoplasmic in confluent cells. The change in E7's location is independent of time in culture, cell division, cell cycle phase or cellular differentiation. Levels of E7 are also increased in confluent cells as determined by Western blotting. Our investigations have also uncovered how different analytical techniques influence the observation of where E7 is localised, highlighting the importance of technical choice in such analysis. Understanding the localisation of E7 will help us to better comprehend the function of E7 on its target proteins

Harnessing Infrared Photons for Photoelectrochemical Hydrogen Generation. A PbS Quantum Dot Based "Quasi-Artificial Leaf"

[EN] Hydrogen generation by using quantum dot (QD) based heterostructures has emerged as a promising strategy to develop artificial photosynthesis devices. In the present study, we sensitize mesoporous TiO2 electrodes with in-situ-deposited PbS/CdS QDs, aiming at harvesting light in both the visible and the near-infrared for hydrogen generation. This heterostructure exhibits a remarkable photocurrent of 6 mA.cm(-2), leading to 60 mL.cm(-2).day(-1) hydrogen generation. Most importantly, confirmation of the contribution of infrared photons to H-2 generation was provided by the incident-photon-to-current-efficiency (IPCE), and the integrated current was in excellent agreement with that obtained through cyclic voltammetry. The main electronic processes (accumulation, transport, and recombination) were identified by impedance spectroscopy, which appears as a simple and reliable methodology to evaluate the limiting factors of these photoelectrodes. On the basis of this TiO2/PbS/CdS heterostructrure, a "quasi-artificial leaf' has been developed, which has proven to produce hydrogen under simulated solar illumination at (4.30 +/- 0.25) mL.cm(-2).day(-1).We acknowledge support by projects from Ministerio de Economia y Competitividad (MINECO) of Spain (Consolider HOPE CSD2007-00007, MAT2010-19827), Generalitat Valenciana (PROMETEO/2009/058 and Project ISIC/2012/008 "Institute of Nanotechnologies for Clean Energies"), and Fundacio Bancaixa (P1.1B2011-50). S.G. acknowledges support by MINECO of Spain under the Ramon y Cajal programme. The SCIC of the University Jaume I de Castello is also acknowledged for the gas analysis measurements. C.S. acknowledges the POSDRU/89/1.5/S/58852 Project "Postdoctoral programme for training scientific researchers", co-financed by the European Social Fund within the Sectorial Operational Program Human Resources Development 2007-2013. We want to acknowledge Prof. J. Bisquert for the fruitful discussions related to this manuscript.Trevisan, R.; Rodenas, P.; González-Pedro, V.; Sima, C.; Sánchez, RS.; Barea, EM.; Mora-Sero, I.... (2013). Harnessing Infrared Photons for Photoelectrochemical Hydrogen Generation. A PbS Quantum Dot Based "Quasi-Artificial Leaf". Journal of Physical Chemistry Letters. 4(1):141-146. https://doi.org/10.1021/jz301890mS1411464

Human Papillomavirus-16 E7 Interacts with Glutathione S-Transferase P1 and Enhances Its Role in Cell Survival

Background:Human Papillomavirus (HPV)-16 is a paradigm for "high-risk" HPVs, the causative agents of virtually all cervical carcinomas. HPV E6 and E7 viral genes are usually expressed in these tumors, suggesting key roles for their gene products, the E6 and E7 oncoproteins, in inducing malignant transformation.Methodology/Principal Findings:By protein-protein interaction analysis, using mass spectrometry, we identified glutathione S-transferase P1-1 (GSTP1) as a novel cellular partner of the HPV-16 E7 oncoprotein. Following mapping of the region in the HPV-16 E7 sequence that is involved in the interaction, we generated a three-dimensional molecular model of the complex between HPV-16 E7 and GSTP1, and used this to engineer a mutant molecule of HPV-16 E7 with strongly reduced affinity for GSTP1.When expressed in HaCaT human keratinocytes, HPV-16 E7 modified the equilibrium between the oxidized and reduced forms of GSTP1, thereby inhibiting JNK phosphorylation and its ability to induce apoptosis. Using GSTP1-deficient MCF-7 cancer cells and siRNA interference targeting GSTP1 in HaCaT keratinocytes expressing either wild-type or mutant HPV-16 E7, we uncovered a pivotal role for GSTP1 in the pro-survival program elicited by its binding with HPV-16 E7.Conclusions/Significance:This study provides further evidence of the transforming abilities of this oncoprotein, setting the groundwork for devising unique molecular tools that can both interfere with the interaction between HPV-16 E7 and GSTP1 and minimize the survival of HPV-16 E7-expressing cancer cells. © 2009 Mileo et al