EC(5)S Ubiquitin Complex Is Recruited by KSHV Latent Antigen LANA for Degradation of the VHL and p53 Tumor Suppressors

Cellular protein degradation pathways can be utilized by viruses to establish an environment that favors their propagation. Here we report that the Kaposi's sarcoma–associated herpesvirus (KSHV)-encoded latency-associated nuclear antigen (LANA) directly functions as a component of the EC(5)S ubiquitin complex targeting the tumor suppressors von Hippel-Lindau (VHL) and p53 for degradation. We have characterized a suppressor of cytokine signaling box-like motif within LANA composed of an Elongin B and C box and a Cullin box, which is spatially located at its amino and carboxyl termini. This motif is necessary for LANA interaction with the Cul5–Elongin BC complex, to promote polyubiquitylation of cellular substrates VHL and p53 in vitro via its amino- and carboxyl-terminal binding domain, respectively. In transfected cells as well as KSHV-infected B lymphoma cells, LANA expression stimulates degradation of VHL and p53. Additionally, specific RNA interference–mediated LANA knockdown stabilized VHL and p53 in primary effusion lymphoma cells. Thus, manipulation of tumor suppressors by LANA potentially provides a favorable environment for progression of KSHV-infected tumor cells

Neural effects of cannabinoid CB1 neutral antagonist tetrahydrocannabivarin (THCv) on food reward and aversion in healthy volunteers

Disturbances in the regulation of reward and aversion in the brain may underlie disorders such as obesity and eating disorders. We previously showed that the cannabis receptor subtype (CB1) inverse agonist rimonabant, an antiobesity drug withdrawn due to depressogenic side effects, diminished neural reward responses yet increased aversive responses (Horder et al., 2010). Unlike rimonabant, tetrahydrocannabivarin is a neutral CB1 receptor antagonist (Pertwee, 2005) and may therefore produce different modulations of the neural reward system. We hypothesized that tetrahydrocannabivarin would, unlike rimonabant, leave intact neural reward responses but augment aversive responses. Methods: We used a within-subject, double-blind design. Twenty healthy volunteers received a single dose of tetrahydrocannabivarin (10mg) and placebo in randomized order on 2 separate occasions. We measured the neural response to rewarding (sight and/or flavor of chocolate) and aversive stimuli (picture of moldy strawberries and/or a less pleasant strawberry taste) using functional magnetic resonance imaging. Volunteers rated pleasantness, intensity, and wanting for each stimulus. Results: There were no significant differences between groups in subjective ratings. However, tetrahydrocannabivarin increased responses to chocolate stimuli in the midbrain, anterior cingulate cortex, caudate, and putamen. Tetrahydrocannabivarin also increased responses to aversive stimuli in the amygdala, insula, mid orbitofrontal cortex, caudate, and putamen. Conclusions: Our findings are the first to show that treatment with the CB1 neutral antagonist tetrahydrocannabivarin increases neural responding to rewarding and aversive stimuli. This effect profile suggests therapeutic activity in obesity, perhaps with a lowered risk of depressive side effects. Keywords: reward, THCv, obesity, fMRI, cannabinoi

The Problem of Experience in the Study of Organizations

This paper deals with the fact that we cannot experience large organizations directly, in the same way as we can experience individuals or small groups, and that this non-experientiability has certain implications for our scientific theories of organizations. Whereas a science is animated by a constructive interplay of theory concepts and experience concepts, the study of organizations has been confined to theory concepts alone. Implications of this analysis for developing a science of organizations are considered.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68303/2/10.1177_017084069301400102.pd

Neural representation of reward in recovered depressed patients

These findings support the view that abnormal neural responses to reward may be an endophenotype for depression and a potential target for intervention and prevention strategies

LANA Promotes Polyubiquitylation of Tumor Suppressors <i>p53</i> and <i>VHL</i>

<div><p>(A) LANA induces <i>p53</i> and <i>VHL</i> polyubiquitylation. Saos-2 (left panel) or 786-O (right panel) cells were cotransfected with different combinations of myc-LANA (WT and ΔSOCS), myc-<i>p53</i> (or HA-VHL), and HA-Ub as indicated. At 48 h posttransfection, transfected cells were harvested, lysed, and protein normalized. Total protein (40 μg) was subjected to resolve and IB assays against myc (LANA), <i>p53</i> (or <i>VHL</i>), and β-actin. The data showed LANA can induce <i>p53</i> and <i>VHL</i> ubiquitylation in vivo.</p><p>(B) The LANA–Elongin BC–Cul5–Rbx1 complex induces <i>p53</i> and <i>VHL</i> polyubiquitylation in vitro. The cell lysates of WT LANA (<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.0020116#ppat-0020116-g003" target="_blank">Figure 3</a>C, lane 4) or SOCS-box–like motif deletion mutant (<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.0020116#ppat-0020116-g003" target="_blank">Figure 3</a>C, lane 3) as control was subjected to anti-myc immunoaffinity purification. The purified LANA immune complex (IC) was incubated with various combinations of Uba1 (E1), Ubc5a (E2), His-Ub, or GST-VHL (or GST-p53) in the presence of ATP in vitro. The proteins were separated by SDS-PAGE and IB against GST antibody. Left panel, GST-p53; right panel, GST-VHL.</p></div