Ubiquitin: Same Molecule, Different Degradation Pathways

Ubiquitin is a common demoninator in the targeting of substrates to all three major protein degradation pathways in mammalian cells: the proteasome, the lysosome, and the autophagosome. The factors that direct a substrate toward a particular route of degradation likely include ubiquitin chain length and linkage type, which may favor interaction with particular receptors or confer differential susceptibility to deubiquitinase activities associated with each pathway

Governance of Endocytic Trafficking and Signaling by Reversible Ubiquitylation

The endosomal pathway provides a major platform for ubiquitin-modifying enzymes, which act upon membrane-associated proteins in transit. Ubiquitylated cargo proteins are recognized by ubiquitin-binding domains inherent to key adaptor proteins at the plasma membrane and sorting endosome. A balance between ubiquitylation and deubiquitylation activities may govern the efficiency of recycling from endosomes to the plasma membrane versus lysosomal sorting through the multivesicular body pathway. We discuss the current knowledge of the properties of adaptors and ubiquitin-modifying proteins and their effects upon the trafficking and signaling of receptors and ligands associated with pathways fundamental to development

The centrosomal deubiquitylase USP21 regulates Gli1 transcriptional activity and stability

USP21 is a centrosome-associated deubiquitylase (DUB) that has been implicated in the formation of primary cilia - crucial organelles for the regulation of the Hedgehog (Hh) signaling pathway in vertebrates. Here, we identify KCTD6 - a cullin-3 E3-ligase substrate adapter that has been previously linked to Hh signaling - as well as Gli1, the key transcription factor responsible for Hh signal amplification, as new interacting partners of USP21. We identify a cryptic structured protein interaction domain in KCTD6, which is predicted to have a similar fold to Smr domains. Importantly, we show that both depletion and overexpression of catalytically active USP21 suppress Gli1-dependent transcription. Gli proteins are negatively regulated through protein kinase A (PKA)-dependent phosphorylation. We provide evidence that USP21 recruits and stabilises Gli1 at the centrosome where it promotes its phosphorylation by PKA. By revealing an intriguing functional pairing between a spatially restricted deubiquitylase and a kinase, our study highlights the centrosome as an important hub for signal coordination

Deciphering histone 2A deubiquitination

The discovery of three different enzymes that deubiquitinate histone 2A

Phosphatidylinositol 3-kinase regulation of fluid phase endocytosis

AbstractEndocytosis of the fluid phase marker, horse radish peroxidase, into baby hamster kidney cells is inhibited by treatment of cells with the fungal metabolite wortmannin. The IC50 of approximately 5 nM is consistent with the well-described action of wortmannin upon phosphatidylinositol (PI) 3-kinase. Analysis of the kinetics of uptake indicates a > 50% decrease in the initial rate of marker internalisation, a concomitant decrease in the volume of the early endosome and an increased efficiency of recycling of that marker which is internalised. As PI 3-kinase binds to activated growth factor receptors our data suggest that receptor activation can be coupled to receptor internalisation (down regulation) by localising PI 3-kinase stimulation of endocytosis

Retain: CPD for Early Career Teachers of KS1 Pilot report and executive summary

Evaluation of professional development programme for early career teachers (ECTs) who are teaching key stage 1 (KS1) pupils in schools in disadvantaged areas cvonducted for the Education endowment Foundation (EEF), which aimed to enhance ECTs' knowledge and use of evidence-informed practices and to retain ECTs in the profession. The mixed methods theory-based evaluation gathered data from interviews, focus groups and surveys of participants and stakeholders to examine evidence of promise and the plausibility of the theory of change. ECTs' knowledge and understanding of approaches to teaching disadvantaged students, self-efficacy, confidence and research-use increased and they made changes in their classroom practice. The absence of a comparison group means that it is not possible to estimate the level of improvement that may have occurred without the programme. Most ECTs perceived that RETAIN was beneficial to their professional and career development and none left the profession during the pilot. Overall, RETAIN was positively received. ECTs found it easier to apply the learning from RETAIN in schools which were open to changing existing school practices and willing to support ECTs in implementing new approaches. Qualitative evidence indicates that the most important components of RETAIN were the taught sessions underpinned by research evidence, coaching by an external coach and peer collaboration, which combine to achieve positive outcomes