Coactivators p300 and PCAF physically and functionally interact with the foamy viral trans-activator

BACKGROUND: Foamy virus Bel1/Tas trans-activators act as key regulators of gene expression and directly bind to Bel1 response elements (BRE) in both the internal and the 5'LTR promoters leading to strong transcriptional trans-activation. Cellular coactivators interacting with Bel1/Tas are unknown to date. RESULTS: Transient expression assays, co-immunoprecipitation experiments, pull-down assays, and Western blot analysis were used to demonstrate that the coactivator p300 and histone acetyltransferase PCAF specifically interact with the retroviral trans-activator Bel1/Tas in vivo. Here we show that the Bel1/Tas-mediated trans-activation was enhanced by the coactivator p300, histone acetyltransferases PCAF and SRC-1 based on the crucial internal promoter BRE. The Bel1/Tas-interacting region was mapped to the C/H1 domain of p300 by co-immunoprecipitation and pull-down assays. In contrast, coactivator SRC-1 previously reported to bind to the C-terminal domain of p300 did not directly interact with the Bel1 protein but nevertheless enhanced Bel1/Tas-mediated trans-activation. Cotransfection of Bel1/Tas and p300C with an expression plasmid containing the C/H1domain partially inhibited the p300C-driven trans-activation. CONCLUSIONS: Our data identify p300 and PCAF as functional partner molecules that directly interact with Bel1/Tas. Since the acetylation activities of the three coactivators reside in or bind to the C-terminal regions of p300, a C/H1 expression plasmid was used as inhibitor. This is the first report of a C/H1 domain-interacting retroviral trans-activator capable of partially blocking the strong Bel1/Tas-mediated activation of the C-terminal region of coactivator p300. The potential mechanisms and functional roles of the three histone and factor acetyltransferases p300, PCAF, and SRC-1 in Bel1/Tas-mediated trans-activation are discussed

A Framework for Exploring the Impact of Tutor Practices on Learner Self-regulation in Online Environments

There is increasing interest in the conceptualization of Self-Regulated learning (SRL) as a dynamic process which unfolds over the course of a learning activity. This is partly because this conceptualization could potentially be operationalized and used as the basis for AI and analytics tools which monitor and scaffold SRL in real-time. However, while there is an abundance of research on theories of SRL, little research explicitly reviews and operationalizes such theoretical considerations. Work is needed to develop frameworks for the practical applications of fundamental SRL theories, helping researchers move from conceptual considerations to operationalization in real world settings. In this paper, we propose a theoretically grounded framework for investigating SRL in the context of online tutoring for upper primary school learners. SRL is interpreted as a social learning construct, and the framework proposed is designed to investigate the influence of tutor practices on the development of learners’ SRL. We present the results of a pilot study that explored the applicability of the framework

Intravenous tocilizumab for the treatment of giant cell arteritis: a phase Ib dose-ranging pharmacokinetic bridging study.

BACKGROUND Subcutaneous tocilizumab (TCZ SC) is approved globally for giant cell arteritis (GCA). This phase Ib study investigated the pharmacokinetics, pharmacodynamics, safety, and exploratory efficacy of intravenous (IV) TCZ 6 and 7 mg/kg in patients with GCA. This study explored an IV dose resulting in a minimum exposure level within the range of effective trough concentrations achieved with TCZ SC dosing in GCA and not exceeding the exposure of the well-tolerated 8 mg/kg IV every 4 weeks (Q4W) in rheumatoid arthritis (RA). METHODS Patients with GCA who had received ≥ 5 doses of TCZ IV 8 mg/kg Q4W and achieved remission were enrolled. Patients received 5 doses of TCZ IV 7 mg/kg Q4W in period 1 and, if still in remission, 5 doses of 6 mg/kg Q4W in period 2. Pharmacokinetic endpoints were maximum concentration (Cmax), minimum concentration (Ctrough), area under the curve over a dosing interval (AUCτ), and mean concentration (Cmean) of TCZ after the last dose of each period. Other endpoints included pharmacodynamic markers, safety, and exploratory efficacy. RESULTS In 24 patients, the median (range) age was 65.5 (57-90) years, and 62.5% were female. TCZ exposures (Cmax and AUCτ) were 11.2% and 20.0% lower at the 6- than 7-mg/kg dose. The mean interleukin 6 (IL-6) serum concentrations were elevated at baseline and remained elevated, with slightly higher concentrations in period 1 than in period 2. The mean serum soluble IL-6 receptor concentrations were elevated at baseline and comparable between the 2 doses at steady state. C-reactive protein levels and most erythrocyte sedimentation rates were within normal ranges throughout the study. Overall, 22 patients (91.7%) had ≥ 1 adverse event, and 4 (16.7%) had a serious adverse event. No patients experienced a GCA flare, and all remained in remission throughout the study. CONCLUSIONS Both doses of TCZ IV Q4W were generally well tolerated in patients with GCA. The Cmax and Cmean achieved with 6 mg/kg IV Q4W in patients with GCA were similar to those in patients with RA treated with 8 mg/kg IV Q4W, and Ctrough was within the range observed in patients with GCA treated with SC dosing every week or every 2 weeks. TRIAL REGISTRATION ClinicalTrials.gov , NCT03923738

Geo-Biological Investigations on Azooxanthellate Cold-Water Coral Reefs on the Carbonate Mounds Along the Celtic Continental Slope

Northeast Atlantic 2004 Cruise No. 61, Leg 1 April 19 to May 4, 2004, Lisbon – Cor

Exploring the functional interaction between POSH and ALIX and the relevance to HIV-1 release

<p>Abstract</p> <p>Background</p> <p>The ALG2-interacting protein X (ALIX)/AIP1 is an adaptor protein with multiple functions in intracellular protein trafficking that plays a central role in the biogenesis of enveloped viruses. The ubiquitin E3-ligase POSH (plenty of SH3) augments HIV-1 egress by facilitating the transport of Gag to the cell membrane. Recently, it was reported, that POSH interacts with ALIX and thereby enhances ALIX mediated phenotypes in <it>Drosophila</it>.</p> <p>Results</p> <p>In this study we identified ALIX as a POSH ubiquitination substrate in human cells: POSH induces the ubiquitination of ALIX that is modified on several lysine residues <it>in vivo </it>and <it>in vitro</it>. This ubiquitination does not destabilize ALIX, suggesting a regulatory function. As it is well established that ALIX rescues virus release of L-domain mutant HIV-1, HIV-1Δ_PTAP, we demonstrated that wild type POSH, but not an ubiquitination inactive RING finger mutant (POSH^V14A), substantially enhances ALIX-mediated release of infectious virions derived from HIV-1Δ_PTAPL-domain mutant (YPX_nL-dependent HIV-1). In further agreement with the idea of a cooperative function of POSH and ALIX, mutating the YPX_nL-ALIX binding site in Gag completely abrogated augmentation of virus release by overexpression of POSH. However, the effect of the POSH-mediated ubiquitination appears to be auxiliary, but not necessary, as silencing of POSH by RNAi does not disturb ALIX-augmentation of virus release.</p> <p>Conclusion</p> <p>Thus, the cumulative results identified ALIX as an ubiquitination substrate of POSH and indicate that POSH and ALIX cooperate to facilitate efficient virus release. However, while ALIX is obligatory for the release of YPX_nL-dependent HIV-1, POSH, albeit rate-limiting, may be functionally interchangeable.</p