Alternate routes to the cell surface underpin insulin-regulated membrane trafficking of GLUT4

Insulin-stimulated delivery of glucose transporters (GLUT4) from specialized intracellular GLUT4 storage vesicles (GSVs) to the surface of fat and muscle cells is central to whole-body glucose. This translocation and subsequent internalization of GLUT4 back into intracellular stores transits numerous small membrane-bound compartments (internal GLUT4-containing vesicles; IGVs) including GSVs, but the function of these different compartments is not clear. Cellugyrin and sortilin define distinct populations of IGV; sortilin-positive IGVs represent GSVs, but the function of cellugyrin-containing IGVs is unknown. Here we demonstrate a role for cellugyrin in intracellular sequestration of GLUT4 in HeLa cells and have used a proximity ligation assay to follow changes in pairwise associations between cellugyrin, sortilin, GLUT4 and membrane trafficking machinery following insulin-stimulation of 3T3-L1 adipoctyes. Our data suggest that insulin stimulates traffic from cellugyrin- to sortilin- membranes, and that cellugyrin-IGVs provide an insulin-sensitive reservoir to replenish GSVs following insulin-stimulated exocytosis of GLUT4. Furthermore, our data support the existence of a pathway from cellugyrin-membranes to the surface of 3T3-L1 adipocytes that bypasses GSVs under basal conditions, and that insulin diverts traffic away from this into GSVs

Bio-encounters

Presented in an exhibition of shortlisted proposals for a new public art work at the Huxley Building, University of Brighton, for Brighton Digital Festival, 14th to 23rd September 2017. This new project proposal for the Huxley Building Public Art Commission is a development on two previous telematic public art installations by Paul Sermon and Charlotte Gould: Screen Machine in 2016 and Peoples Screen from 2015, originally commissioned by Public Art Lab Berlin for the Connecting Cities network of urban screen projects. In this new project entitled ‘Bio-encounters’ Sermon and Gould have considered the technical and conceptual aspects of the former works to develop and propose an original site-specific interactive telematic art installation, linking live audience groups between indoor and outdoor entrance areas at the Huxley building. This new installation pushes the playful, social and public engagement aspects of their work into new arts and science realms in an attempt to address the pharmacy and biomolecular themes of the commission. The proposed project picks up on the need for a shared visual language and experience that allows a diverse public audience to physically engage with the current research and taught subjects in the Huxley Building through improvised performative interaction as their means of visual dialogue. Using a tried and tested telematic concept and technique, the installation takes live oblique camera shots from above the screens of two separate audience groups connected over a networked video link. Both groups are located on retro-reflective green-screen steps, and are then combined via a chroma-key video switcher in a single composited image displayed simultaneously on each screen. As the merged audiences start to explore this collaborative, shared telepresent space they discover the ground beneath them, as it appears on screen as a digital backdrop, locates them in a variety of surprising and intriguing anamorphic biomolecular environments. These backgrounds directly reference their scientific and social settings, containing converged scenes from these communities in a three dimensional ludic landscape