Virus taxonomy: the database of the International Committee on Taxonomy of Viruses (ICTV)

The International Committee on Taxonomy of Viruses (ICTV) is charged with the task of developing, refining, and maintaining a universal virus taxonomy. This task encompasses the classification of virus species and higher-level taxa according to the genetic and biological properties of their members; naming virus taxa; maintaining a database detailing the currently approved taxonomy; and providing the database, supporting proposals, and other virus-related information from an open-access, public web site. The ICTV web site (http://ictv.global) provides access to the current taxonomy database in online and downloadable formats, and maintains a complete history of virus taxa back to the first release in 1971. The ICTV has also published the ICTV Report on Virus Taxonomy starting in 1971. This Report provides a comprehensive description of all virus taxa covering virus structure, genome structure, biology and phylogenetics. The ninth ICTV report, published in 2012, is available as an open-access online publication from the ICTV web site. The current, 10th report (http://ictv.global/report/), is being published online, and is replacing the previous hard-copy edition with a completely open access, continuously updated publication. No other database or resource exists that provides such a comprehensive, fully annotated compendium of information on virus taxa and taxonomy

Regulation of Membrane Targeting of the G Protein-coupled Receptor Kinase 2 by Protein Kinase A and Its Anchoring Protein AKAP79

The beta 2 adrenergic receptor (beta 2AR) undergoes desensitization by a process involving its phosphorylation by both protein kinase A (PKA) and G protein-coupled receptor kinases (GRKs). The protein kinase A-anchoring protein AKAP79 influences beta 2AR phosphorylation by complexing PKA with the receptor at the membrane. Here we show that AKAP79 also regulates the ability of GRK2 to phosphorylate agonist-occupied receptors. In human embryonic kidney 293 cells, overexpression of AKAP79 enhances agonist-induced phosphorylation of both the beta 2AR and a mutant of the receptor that cannot be phosphorylated by PKA (beta 2AR/PKA-). Mutants of AKAP79 that do not bind PKA or target to the beta 2AR markedly inhibit phosphorylation of beta 2AR/PKA-. We show that PKA directly phosphorylates GRK2 on serine 685. This modification increases Gbeta gamma subunit binding to GRK2 and thus enhances the ability of the kinase to translocate to the membrane and phosphorylate the receptor. Abrogation of the phosphorylation of serine 685 on GRK2 by mutagenesis (S685A) or by expression of a dominant negative AKAP79 mutant reduces GRK2-mediated translocation to beta 2AR and phosphorylation of agonist-occupied beta 2AR, thus reducing subsequent receptor internalization. Agonist-stimulated PKA-mediated phosphorylation of GRK2 may represent a mechanism for enhancing receptor phosphorylation and desensitization

The Effect of Caffeic Acid Phenethyl Ester (CAPE) on H2O2-Induced Oxidative Stress in Cultured H9c2 Cells Compared to Common Antioxidants

Caffeic Acid Phenethyl Ester (CAPE) is a natural compound that has previously exhibited anti-proliferative, anti-inflammation and antioxidant activities. However, CAPE’s effects have not been fully elucidated in myoblasts under oxidative stress. We compared the effects of 24 hour pretreatment of CAPE to several known antioxidants (caffeic acid, vitamin C, and trolox) in H9c2 cells following oxidative injury by hydrogen peroxide (H2O2). H9c2 cells incubated with H2O2 treatment (100-700 μM, n=4) for 24 hours dose-dependently reduced cell viability (assessed by a cell counting assay). Compared to the reduction in viability from H2O2 500 μM treatment (22 ± 4%), H9c2 cell viability was significantly restored by pretreatment of CAPE (at 10 μM (100 ± 25%); 20 μM (112 ± 15%); 40 μM (109 ± 15%) n=5, p\u3c0.001) and Trolox (at 50 μM (83 ± 10%); 100 μM (89 ± 8%) n=4, p\u3c0.001). In contrast, pretreatment of H9c2 cells with caffeic acid (1-80 μM, n=3) and vitamin C (1000-10,000 μM, n=3) did not restore cell viability following H2O2-induced injury. CAPE’s mechanism was further investigated by measuring reactive oxygen species via a dichlorofluorescin diacetate assay and by evaluating heme oxygenase-1 (HO-1) expression via western blot. Increases in ROS caused by H2O2 500 μM (239 ± 30% of control, n=3) were significantly restored to control by pretreatment of CAPE dose-dependently (n=3, p\u3c0.001). Moreover, CAPE dose-dependently increased HO-1 expression (n=3). These results suggest CAPE can mitigate oxidative stress in H9c2 cells which may involve the induction of HO-1

Regions of the a1adrenergic receptor involved in coupling to phosphatidylinositol hydrolysis and enhanced sensitivity of biological function

ABSTRACT Regions of the hamster a1-adrenergic receptor (aAR) EXPERIMENTAL PROCEDURES Plasmids. For the construction of chimeric 132/aiAR, residues 228-295 of the hamster a1AR (1) were substituted for residues 224-274 of the human fi2AR (6) by splicing the desired restriction fragments of DNA encoding the wild-type receptors with synthetic oligonucleotide adapters. For expression studies, the f32AR and chimeric P2/aAR were subcloned into the expression vector pBC12BI (18) as described (19). For construction of the ajAR mutants, singlestranded DNA was prepared from pTZ18R (Pharmacia) containing the cDNA of the a1AR and used for oligonucleotidedirected mutagenesis (Amersham). The identity of each mutant was confirmed by dideoxy sequencing of single-and double-stranded DNA with Sequenase (United States Biochemical). For expression studies, the expression vector pBCa1 (19) was digested with Xho I and Apa I and ligated to the Xho I-Apa I restriction fragments of each mutated ajAR species to obtain pBC12BI plasmids containing the DNA for each mutated receptor. Mammalian Cell Expression. COS-7 cells were grown in Dulbecco's modified Eagle's medium (DMEM) supplemented with gentamicin (100 ,ug/ml) and 10%o fetal bovine serum (GIBCO). COS-7 cells were transfected by the DEAEdextran metho

Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2016)

This article lists the changes to virus taxonomy approved and ratified by the International Committee on Taxonomy of Viruses (ICTV) in April 2016. Changes to virus taxonomy (the Universal Scheme of Virus Classification of the International Committee on Taxonomy of Viruses [ICTV]) now take place annually and are the result of a multi-stage process. In accordance with the ICTV Statutes (http://​www.​ictvonline.​org/​statutes.​asp), proposals submitted to the ICTV Executive Committee (EC) undergo a review process that involves input from the ICTV Study Groups (SGs) and Subcommittees (SCs), other interested virologists, and the EC. After final approval by the EC, proposals are then presented for ratification to the full ICTV membership by publication on an ICTV web site (http://​www.​ictvonline.​org/​) followed by an electronic vote. The latest set of proposals approved by the EC was made available on the ICTV website by January 2016 (https://​talk.​ictvonline.​org/​files/​proposals/​). A list of these proposals was then emailed on 28 March 2016 to the 148 members of ICTV, namely the EC Members, Life Members, ICTV Subcommittee Members (including the SG chairs) and ICTV National Representatives. Members were then requested to vote on whether to ratify the taxonomic proposals (voting closed on 29 April 2016)

β-Arrestins Regulate Protease-activated Receptor-1 Desensitization but Not Internalization or Down-regulation

The widely expressed beta-arrestin isoforms 1 and 2 bind phosphorylated G protein-coupled receptors (GPCRs) and mediate desensitization and internalization. Phosphorylation of protease-activated receptor-1 (PAR1), a GPCR for thrombin, is important for desensitization and internalization, however, the role of beta-arrestins in signaling and trafficking of PAR1 remains unknown. To assess beta-arrestin function we examined signaling and trafficking of PAR1 in mouse embryonic fibroblasts (MEFs) derived from beta-arrestin (betaarr) knockouts. Desensitization of PAR1 signaling was markedly impaired in MEFs lacking both betaarr1 and betaarr2 isoforms compared with wild-type cells. Strikingly, in cells lacking only betaarr1 PAR1 desensitization was also significantly impaired compared with betaarr2-lacking or wild-type cells. In wild-type MEFs, activated PAR1 was internalized through a dynamin- and clathrin-dependent pathway and degraded. Surprisingly, in cells lacking both betaarr1 and betaarr2 activated PAR1 was similarly internalized through a dynamin- and clathrin-dependent pathway and degraded, whereas the beta(2)-adrenergic receptor (beta(2)-AR) failed to internalize. A PAR1 cytoplasmic tail mutant defective in agonist-induced phosphorylation failed to internalize in both wild-type and beta-arrestin knockout cells. Thus, PAR1 appears to utilize a distinct phosphorylation-dependent but beta-arrestin-independent pathway for internalization through clathrin-coated pits. Together, these findings strongly suggest that the individual beta-arrestin isoforms can differentially regulate GPCR desensitization and further reveal a novel mechanism by which GPCRs can internalize through a dynamin- and clathrin-dependent pathway that is independent of arrestins

β 2 -Adrenergic Receptor Signaling and Desensitization Elucidated by Quantitative Modeling of Real Time cAMP Dynamics

G protein-coupled receptor signaling is dynamically regulated by multiple feedback mechanisms, which rapidly attenuate signals elicited by ligand stimulation, causing desensitization. The individual contributions of these mechanisms, however, are poorly understood. Here, we use an improved fluorescent biosensor for cAMP to measure second messenger dynamics stimulated by endogenous beta(2)-adrenergic receptor (beta(2)AR) in living cells. beta(2)AR stimulation with isoproterenol results in a transient pulse of cAMP, reaching a maximal concentration of approximately 10 microm and persisting for less than 5 min. We investigated the contributions of cAMP-dependent kinase, G protein-coupled receptor kinases, and beta-arrestin to the regulation of beta(2)AR signal kinetics by using small molecule inhibitors, small interfering RNAs, and mouse embryonic fibroblasts. We found that the cAMP response is restricted in duration by two distinct mechanisms in HEK-293 cells: G protein-coupled receptor kinase (GRK6)-mediated receptor phosphorylation leading to beta-arrestin mediated receptor inactivation and cAMP-dependent kinase-mediated induction of cAMP metabolism by phosphodiesterases. A mathematical model of beta(2)AR signal kinetics, fit to these data, revealed that direct receptor inactivation by cAMP-dependent kinase is insignificant but that GRK6/beta-arrestin-mediated inactivation is rapid and profound, occurring with a half-time of 70 s. This quantitative system analysis represents an important advance toward quantifying mechanisms contributing to the physiological regulation of receptor signaling

Enhanced Rewarding Properties of Morphine, but not Cocaine, in βarrestin-2 Knock-Out Mice

The reinforcing and psychomotor effects of morphine involve opiate stimulation of the dopaminergic system via activation of mu-opioid receptors (muOR). Both mu-opioid and dopamine receptors are members of the G-protein-coupled receptor (GPCR) family of proteins. GPCRs are known to undergo desensitization involving phosphorylation of the receptor and the subsequent binding of beta(arrestins), which prevents further receptor-G-protein coupling. Mice lacking beta(arrestin)-2 (beta(arr2)) display enhanced sensitivity to morphine in tests of pain perception attributable to impaired desensitization of muOR. However, whether abrogating muOR desensitization affects the reinforcing and psychomotor properties of morphine has remained unexplored. In the present study, we examined this question by assessing the effects of morphine and cocaine on locomotor activity, behavioral sensitization, conditioned place preference, and striatal dopamine release in beta(arr2) knock-out (beta(arr2)-KO) mice and their wild-type (WT) controls. Cocaine treatment resulted in very similar neurochemical and behavioral responses between the genotypes. However, in the beta(arr2)-KO mice, morphine induced more pronounced increases in striatal extracellular dopamine than in WT mice. Moreover, the rewarding properties of morphine in the conditioned place preference test were greater in the beta(arr2)-KO mice when compared with the WT mice. Thus, beta(arr2) appears to play a more important role in the dopaminergic effects mediated by morphine than those induced by cocaine

Essential role of beta-adrenergic receptor kinase 1 in cardiac development and function

The beta-adrenergic receptor kinase 1 (beta ARK1) is a member of the G protein-coupled receptor kinase (GRK) family that mediates the agonist-dependent phosphorylation and desensitization of G protein-coupled receptors. We have cloned and disrupted the beta ARK1 gene in mice by homologous recombination. No homozygote beta ARK1-/- embryos survive beyond gestational day 15.5. Prior to gestational day 15.5, beta ARK1-/- embryos display pronounced hypoplasia of the ventricular myocardium essentially identical to the "thin myocardium syndrome" observed upon gene inactivation of several transcription factors (RXR alpha, N-myc, TEF-1, WT-1). Lethality in beta ARK1-/- embryos is likely due to heart failure as they exhibit a > 70% decrease in cardiac ejection fraction determined by direct in utero intravital microscopy. These results along with the virtual absence of endogenous GRK activity in beta ARK1-/- embryos demonstrate that beta ARK1 appears to be the predominant GRK in early embryogenesis and that it plays a fundamental role in cardiac development