Towards understanding the implications of social role manipulation in online tasks

This paper provides an initial discussion of the ethical issues arising when people are asked to assume a role and, from the perspective of that role, asked to carry out an online task. We identify the following considerations: (a) People’s responses when playing a role can reveal personal information about themselves. (b) When people are asked to review the contributions of others who have a particular role, their behavior might indicate how they feel about these roles in their own life. (c) It is difficult to explain to people what they reveal about themselves when reporting their perception of the views of others. (d) People’s own view might change when they play a certain role for an extended period of time

Mutations in the intellectual disability gene Ube2a cause neuronal dysfunction and impair parkin-dependent mitophagy

The prevalence of intellectual disability is around 3%; however, the etiology of the disease remains unclear in most cases. We identified a series of patients with X-linked intellectual disability presenting mutations in the Rad6a (Ube2a) gene, which encodes for an E2 ubiquitin-conjugating enzyme. Drosophila deficient for dRad6 display defective synaptic function as a consequence of mitochondrial failure. Similarly, mouse mRad6a (Ube2a) knockout and patient-derived hRad6a (Ube2a) mutant cells show defective mitochondria. Using in vitro and in vivo ubiquitination assays, we show that RAD6A acts as an E2 ubiquitin-conjugating enzyme that, in combination with an E3 ubiquitin ligase such as Parkin, ubiquitinates mitochondrial proteins to facilitate the clearance of dysfunctional mitochondria in cells. Hence, we identify RAD6A as a regulator of Parkin-dependent mitophagy and establish a critical role for RAD6A in maintaining neuronal function

Insights into the molecular determinants involved in cap recognition by the vaccinia virus D10 decapping enzyme

Decapping enzymes are required for the removal of the 5′-end m7GpppN cap of mRNAs to allow their decay in cells. While many cap-binding proteins recognize the cap structure via the stacking of the methylated guanosine ring between two aromatic residues, the precise mechanism of cap recognition by decapping enzymes has yet to be determined. In order to get insights into the interaction of decapping enzymes with the cap structure, we studied the vaccinia virus D10 decapping enzyme as a model to investigate the important features for substrate recognition by the enzyme. We demonstrate that a number of chemically modified purines can competitively inhibit the decapping reaction, highlighting the molecular features of the cap structure that are required for recognition by the enzyme, such as the nature of the moiety at positions 2 and 6 of the guanine base. A 3D structural model of the D10 protein was generated which suggests amino acids implicated in cap binding. Consequently, we expressed 17 mutant proteins with amino acid substitutions in the active site of D10 and found that eight are critical for the decapping activity. These data underscore the functional features involved in the non-canonical cap-recognition by the vaccinia virus D10 decapping enzyme

Combinatorial Computational Approaches to Identify Tetracycline Derivatives as Flavivirus Inhibitors

Limited structural information of drug targets, cellular toxicity possessed by lead compounds, and large amounts of potential leads are the major issues facing the design-oriented approach of discovering new leads. In an attempt to tackle these issues, we have developed a process of virtual screening based on the observation that conformational rearrangements of the dengue virus envelope protein are essential for the mediation of viral entry into host cells via membrane fusion. Screening was based solely on the structural information of the Dengue virus envelope protein and was focused on a target site that is presumably important for the conformational rearrangements necessary for viral entry. To circumvent the issue of lead compound toxicity, we performed screening based on molecular docking using structural databases of medical compounds. To enhance the identification of hits, we further categorized and selected candidates according to their novel structural characteristics. Finally, the selected candidates were subjected to a biological validation assay to assess inhibition of Dengue virus propagation in mammalian host cells using a plaque formation assay. Among the 10 compounds examined, rolitetracycline and doxycycline significantly inhibited plaque formation, demonstrating their inhibitory effect on dengue virus propagation. Both compounds were tetracycline derivatives with IC(50)s estimated to be 67.1 µM and 55.6 µM, respectively. Their docked conformations displayed common hydrophobic interactions with critical residues that affected membrane fusion during viral entry. These interactions will therefore position the tetracyclic ring moieties of both inhibitors to bind firmly to the target and, subsequently, disrupt conformational rearrangement and block viral entry. This process can be applied to other drug targets in which conformational rearrangement is critical to function

Loss of yata, a Novel Gene Regulating the Subcellular Localization of APPL, Induces Deterioration of Neural Tissues and Lifespan Shortening

Background: The subcellular localization of membrane and secreted proteins is finely and dynamically regulated through intracellular vesicular trafficking for permitting various biological processes. Drosophila Amyloid precursor protein like (APPL) and Hikaru genki (HIG) are examples of proteins that show differential subcellular localization among several developmental stages. Methodology/Principal Findings: During the study of the localization mechanisms of APPL and HIG, we isolated a novel mutant of the gene, CG1973, which we named yata. This molecule interacted genetically with Appl and is structurally similar to mouse NTKL/SCYL1, whose mutation was reported to cause neurodegeneration. yata null mutants showed phenotypes that included developmental abnormalities, progressive eye vacuolization, brain volume reduction, and lifespan shortening. Exogenous expression of Appl or hig in neurons partially rescued the mutant phenotypes of yata. Conversely, the phenotypes were exacerbated in double null mutants for yata and Appl. We also examined the subcellular localization of endogenous APPL and exogenously pulse-induced APPL tagged with FLAG by immunostaining the pupal brain and larval motor neurons in yata mutants. Our data revealed that yata mutants showed impaired subcellular localization of APPL. Finally, yata mutant pupal brains occasionally showed aberrant accumulation of Sec23p, a component of the COPII coat of secretory vesicles traveling from the endoplasmic reticulum (ER) to the Golgi

Evolution of the Sequence Composition of Flaviviruses

The adaption of pathogens to their host(s) is a major factor in the emergence of infectious disease and the persistent survival of many of the infectious diseases within the population. Since many of the smaller viral pathogens are entirely dependent upon host machinery, it has been postulated that they are under selection for a composition similar to that of their host. Analyses of sequence composition have been conducted for numerous small viral species including the Flavivirus genus. Examination of the species within this particular genus that infect vertebrate hosts revealed that sequence composition proclivities do not correspond with vector transmission as the evolutionary history of this species suggests. Recent sequencing efforts have generated complete genomes for many viral species including members of the Flavivirus genus. A thorough comparison of the sequence composition was conducted for all of the available Flaviviruses for which the complete genome is publicly available. This effort expands the work of previous studies to include new vector-borne species as well as members of the insect-specific group which previously have not been explored. Metrics, including mono-, di-, and trinucleotide abundances as well as NC values and codon usage preferences, were explored both for the entire polyprotein sequence as well as for each individual coding region. Preferences for compositions correspond to host-range rather than evolutionary history; species which infect vertebrate hosts exhibited particular preferences similar to each other as well as in correspondence with their host’s preferences. Flaviviruses which do not infect vertebrate hosts, however, did not show these proclivities, with the exception of the Kamiti River virus suggesting its recent (either past or present) infectivity of an unknown vertebrate host

Molecular characterization and antiviral activity test of common drugs against echovirus 18 isolated in Korea

Genetic diversity and antiviral activity for five common antiviral drugs of echovirus (ECV) 5 isolated in Korea have been described. The present study extended these tests to a Korean ECV 18 isolate. An outbreak of aseptic meningitis caused by the ECV 18 isolate was reported in Korea in 2005, marking the first time this virus had been identified in the country since enterovirus surveillance began in 1993. Using a sample isolated from stool specimen of a 5-year-old male patient with aseptic meningitis, the complete genome sequence was obtained and was compared it with the Metcalf prototype strain. Unlike the ECV5 isolate, the 3' untranslated region had the highest identity value (94.2%) at the nucleotide level, while, at the amino acid level, the P2 region displayed the highest identity value (96.9%). These two strains shared all cleavage sites, with the exception of the 2B/2C site, which was RQ/NN in the Metcalf strain but RQ/NS in the Korean ECV 18 isolate. In Vero cells infected with the Korean ECV 18 isolate, no cytotoxicity was observed in the presence of azidothymidine, acyclovir, amantadine, lamivudine, or ribavirin, when the drugs were administered at a CC50 value >100 μg/mL. Of the five drugs, only amantadine (IC50: 4.97 ± 0.77 μg/mL, TI: 20.12) and ribavirin (IC50: 7.63 ± 0.87 μg/mL, TI: 13.11) had any antiviral activity against the Korean ECV 18 isolate in the five antiviral drugs. These antiviral activity effects were similar with results of the Korean ECV5 isolate

Cell Type Mediated Resistance of Vesicular Stomatitis Virus and Sendai Virus to Ribavirin

Ribavirin (RBV) is a synthetic nucleoside analog with broad spectrum antiviral activity. Although RBV is approved for the treatment of hepatitis C virus, respiratory syncytial virus, and Lassa fever virus infections, its mechanism of action and therapeutic efficacy remains highly controversial. Recent reports show that the development of cell-based resistance after continuous RBV treatment via decreased RBV uptake can greatly limit its efficacy. Here, we examined whether certain cell types are naturally resistant to RBV even without prior drug exposure. Seven different cell lines from various host species were compared for RBV antiviral activity against two nonsegmented negative-strand RNA viruses, vesicular stomatitis virus (VSV, a rhabdovirus) and Sendai virus (SeV, a paramyxovirus). Our results show striking differences between cell types in their response to RBV, ranging from virtually no antiviral effect to very effective inhibition of viral replication. Despite differences in viral replication kinetics for VSV and SeV in the seven cell lines, the observed pattern of RBV resistance was very similar for both viruses, suggesting that cellular rather than viral determinants play a major role in this resistance. While none of the tested cell lines was defective in RBV uptake, dramatic variations were observed in the long-term accumulation of RBV in different cell types, and it correlated with the antiviral efficacy of RBV. While addition of guanosine neutralized RBV only in cells already highly resistant to RBV, actinomycin D almost completely reversed the RBV effect (but not uptake) in all cell lines. Together, our data suggest that RBV may inhibit the same virus via different mechanisms in different cell types depending on the intracellular RBV metabolism. Our results strongly point out the importance of using multiple cell lines of different origin when antiviral efficacy and potency are examined for new as well as established drugs in vitro

The amyloid precursor protein controls PIKfyve function

While the Amyloid Precursor Protein (APP) plays a central role in Alzheimer's disease, its cellular function still remains largely unclear. It was our goal to establish APP function which will provide insights into APP's implication in Alzheimer's disease. Using our recently developed proteo-liposome assay we established the interactome of APP's intracellular domain (known as AICD), thereby identifying novel APP interactors that provide mechanistic insights into APP function. By combining biochemical, cell biological and genetic approaches we validated the functional significance of one of these novel interactors. Here we show that APP binds the PIKfyve complex, an essential kinase for the synthesis of the endosomal phosphoinositide phosphatidylinositol-3,5-bisphosphate. This signalling lipid plays a crucial role in endosomal homeostasis and receptor sorting. Loss of PIKfyve function by mutation causes profound neurodegeneration in mammals. Using C. elegans genetics we demonstrate that APP functionally cooperates with PIKfyve in vivo. This regulation is required for maintaining endosomal and neuronal function. Our findings establish an unexpected role for APP in the regulation of endosomal phosphoinositide metabolism with dramatic consequences for endosomal biology and important implications for our understanding of Alzheimer's disease