Consequences of Gut Dysbiosis on the Human Brain

The central nervous system (CNS) and the gastrointestinal (GI) tract develop in parallel and communicate with each other throughout life using neural, endocrine, and immune pathways, giving rise to the concept of a ‘gut-brain axis’ in which both organ systems intimately interact. Fundamental to the axis is the GI microbiome, which is the collective genomic aggregate of bacteria and other microorganisms that dwell within the lumen of the GI tract. Increasing evidence gathered from animal models and human studies demonstrates that perturbation of the microbiome, otherwise known as dysbiosis, can lead to specific neurological and psychiatric disorders. This chapter will provide a brief review of the literature that reveals the influence of the microbiome in CNS disease and provide perspectives in treatment through modification of the microbiome

Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors

<p>Abstract</p> <p>Background</p> <p>Integration of retroviral DNA into the host cell genome is an obligatory step in the virus life cycle. In previous reports we identified a sequence (amino acids 201–236) in the linker region between the catalytic core and C-terminal domains of the avian sarcoma virus (ASV) integrase protein that functions as a transferable nuclear localization signal (NLS) in mammalian cells. The sequence is distinct from all known NLSs but, like many, contains basic residues that are essential for activity.</p> <p>Results</p> <p>Our present studies with digitonin-permeabilized HeLa cells show that nuclear import mediated by the NLS of ASV integrase is an active, saturable, and ATP-dependent process. As expected for transport through nuclear pore complexes, import is blocked by treatment of cells with wheat germ agglutinin. We also show that import of ASV integrase requires soluble cellular factors but does not depend on binding the classical adapter Importin-α. Results from competition studies indicate that ASV integrase relies on one or more of the soluble components that mediate transport of the linker histone H1.</p> <p>Conclusion</p> <p>These results are consistent with a role for ASV integrase and cytoplasmic cellular factors in the nuclear import of its viral DNA substrate, and lay the foundation for identification of host cell components that mediate this reaction.</p

The Effects of Glucose on Liver X Receptor Function: Implications for Diabetes and Atherosclerosis

High cholesterol and diabetes are major risk factors for atherosclerosis, a disease characterized by the accumulation of lipid-laden macrophages in the artery walls. Regression of atherosclerosis is mediated in part by the Liver X Receptor (LXR), a transcription factor that induces the expression of genes involved in cholesterol transport and efflux. Importantly, regression of atherosclerosis is impaired in diabetes. I proposed that changes in glucose levels are important modulators of LXR gene expression. Using a mouse macrophage cell line (RAW 264.7) as well as primary bone marrow derived macrophages (BMDMs) cultured in normal or diabetes relevant high glucose conditions I found that high glucose inhibits the expression of ATP binding cassette transporter A1 (ABCA1), an LXR target that is central to the efflux of cholesterol from lipid-loaded macrophages. To begin to understand the mechanism whereby glucose imparts these differences, I performed a qPCR-based array that surveys all known chromatin modifying enzymes and found that Protein Arginine Methyltransferase 2 (PRMT2), a member of the Protein arginine methyltransferase family of enzymes that catalyze the N-methylation of proteins at arginine residues, was more highly expressed under normal compared to high glucose conditions. Using bone marrow derived macrophages from PRMT2 knockout mice I observed a decrease in ABCA1 compared to wild type cells and a corresponding decrease in ABCA1-mediated cholesterol efflux. These findings show an intriguing role for PRMT2 in modulating a gene involved in cholesterol homeostasis as well as the negative consequence of elevated glucose decreasing PRMT2 expression. Understanding the mechanisms whereby glucose impacts LXR gene regulatory functions could inform new approaches for treating diabetes and atherosclerosis

Non-stationarity Detection in Model-Free Reinforcement Learning via Value Function Monitoring

The remarkable success achieved by Reinforcement learning (RL) in recent years is mostly confined to stationary environments. In realistic settings, RL agents can encounter non-stationarity when the environmental dynamics change over time. Detecting when this change occurs is crucial for activating adaptation mechanisms at the right time. Existing research on change detection mostly relies on model-based techniques which are challenging for tasks with large state and action spaces. In this paper, we propose a model-free, low-cost approach based on value functions (V or Q) for detecting non-stationarity. The proposed approach calculates the change in the value function (ΔV or ΔQ ) and monitors the distribution of this change over time. Statistical hypothesis testing is used to detect if the distribution of ΔV or ΔQ changes significantly over time, reflecting non-stationarity. We evaluate the proposed approach in three benchmark RL environments and show that it can successfully detect non-stationarity when changes in the environmental dynamics are introduced at different magnitudes and speeds. Our experiments also show that changes in ΔV or ΔQ can be used for context identification leading to a classification accuracy of up to 88%.</p

Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors-3

Ed to GFP (IBB-GFP) was examined in the absence (top) and presence (bottom) of excess unlabeled histone H1. Incubations were for 30 min and all exposure times were equivalent.<p><b>Copyright information:</b></p><p>Taken from "Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors"</p><p>http://www.retrovirology.com/content/5/1/73</p><p>Retrovirology 2008;5():73-73.</p><p>Published online 7 Aug 2008</p><p>PMCID:PMC2527327.</p><p></p

Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors-1

Min at 37°C prior to fixation with paraformaldehyde and staining with fluorescent antibody against GST. Left column panels are import without added cytosol and right column panels with added HeLa cytosol extracts.<p><b>Copyright information:</b></p><p>Taken from "Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors"</p><p>http://www.retrovirology.com/content/5/1/73</p><p>Retrovirology 2008;5():73-73.</p><p>Published online 7 Aug 2008</p><p>PMCID:PMC2527327.</p><p></p

Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors-5

Sport mixture containing the ASV-BSA conjugate, the SV40-BSA conjugate, or Texas red-labeled BSA (TR-BSA). Top panels: Visualization of Texas red conjugates by fluorescence microscopy. Bottom panels: Differential interference contrast (DIC) microscopy of the same field to show preservation of cell integrity. . Digitonin permeabilized HeLa cells were untreated (no addition), treated with 50 μg/ml wheat germ agglutinin (WGA), or 50 units/ml apyrase (Apyrase) prior to incubation with complete transport mixture containing either the ASV-BSA or the SV40-BSA import substrates. . Free NLS peptides were added to the import reactions in molar excess of the import substrates as indicated. "Self" signifies competition with the homologous peptides; "Cross" indicates competition for ASV-BSA import by excess SV40TAg NLS peptide or competition for SV40-BSA import by excess ASV NLS peptide. The left column panels show import in the absence of competitor peptides. . Depletion of ASV-BSA import factor(s) from cytosolic extracts. All assays included Texas-Red labeled ASV-BSA except that shown in the lower left hand corner (panel 4) which included Texas-Red labeled SV40-BSA. Cytosol was either not treated (1; no depletion) or pretreated with glutathione-beads that bound GST alone (2) or fusion proteins of GST plus IN(1–207) which lacks the IN NLS (3), full-length IN(1–286) (5), or a fragment of IN(201–236) that contains the IN NLS (panels 4 and 6).<p><b>Copyright information:</b></p><p>Taken from "Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors"</p><p>http://www.retrovirology.com/content/5/1/73</p><p>Retrovirology 2008;5():73-73.</p><p>Published online 7 Aug 2008</p><p>PMCID:PMC2527327.</p><p></p

Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors-4

Ious times (labeled above each column) at 37°C prior to fixation with paraformaldehyde and staining with fluorescent antibody against GST. The fusion protein used in each row is labeled at the right and the properties described in the text. Fusion proteins that are imported with slower kinetics are grouped at the top (rows 1–4), and those with faster kinetics in the middle (rows 5 and 6). Control fusion proteins that are not imported into the nucleus are in rows 7 and 8.<p><b>Copyright information:</b></p><p>Taken from "Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors"</p><p>http://www.retrovirology.com/content/5/1/73</p><p>Retrovirology 2008;5():73-73.</p><p>Published online 7 Aug 2008</p><p>PMCID:PMC2527327.</p><p></p

Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors-0

Sport mixture containing the ASV-BSA conjugate, the SV40-BSA conjugate, or Texas red-labeled BSA (TR-BSA). Top panels: Visualization of Texas red conjugates by fluorescence microscopy. Bottom panels: Differential interference contrast (DIC) microscopy of the same field to show preservation of cell integrity. . Digitonin permeabilized HeLa cells were untreated (no addition), treated with 50 μg/ml wheat germ agglutinin (WGA), or 50 units/ml apyrase (Apyrase) prior to incubation with complete transport mixture containing either the ASV-BSA or the SV40-BSA import substrates. . Free NLS peptides were added to the import reactions in molar excess of the import substrates as indicated. "Self" signifies competition with the homologous peptides; "Cross" indicates competition for ASV-BSA import by excess SV40TAg NLS peptide or competition for SV40-BSA import by excess ASV NLS peptide. The left column panels show import in the absence of competitor peptides. . Depletion of ASV-BSA import factor(s) from cytosolic extracts. All assays included Texas-Red labeled ASV-BSA except that shown in the lower left hand corner (panel 4) which included Texas-Red labeled SV40-BSA. Cytosol was either not treated (1; no depletion) or pretreated with glutathione-beads that bound GST alone (2) or fusion proteins of GST plus IN(1–207) which lacks the IN NLS (3), full-length IN(1–286) (5), or a fragment of IN(201–236) that contains the IN NLS (panels 4 and 6).<p><b>Copyright information:</b></p><p>Taken from "Nuclear import of Avian Sarcoma Virus integrase is facilitated by host cell factors"</p><p>http://www.retrovirology.com/content/5/1/73</p><p>Retrovirology 2008;5():73-73.</p><p>Published online 7 Aug 2008</p><p>PMCID:PMC2527327.</p><p></p